THE PHYSICS OF CHARM AND BEAUTY

SECTION 5

Table of Contents

5.1 Introduction............................................................................................................................................ 1

5.2 E400 - charmed particle production by neutrons........................................................ 3

5.3 E653 - Charm and Beauty Decays in a Hybrid Emulsion Spectrometer............ 6

5.4 E672 - Hadronic Final States in Association with High Mass Dimuons............ 10

5.5 E687 - Photoproduction of Charm and Beauty.............................................................. 15

5.6 E691 - Charm Production with the Tagged Photon Spectrometer................ 20

5.7 E743 - charm production in pp collisions with lebc-fmps................................... 25

5.8 E769 - Hadroproduction of charm......................................................................................... 29

5.9 E771 - Beauty Production by Protons................................................................................... 33

5.10 E781/SELEX - Study of Charm Baryon Physics................................................................... 37

5.11 E789 - beauty-Quark Mesons and Baryons.......................................................................... 40

5.12 E791 - Hadroproduction of Charm......................................................................................... 43

5.13 E831/FOCUS - Heavy Quarks study Using the Wideband Photon Beam.............. 48

5. PHYSICS OF CHARM AND BEAUTY

5.1 Introduction

Two of the fundamental particles of the standard model are the charm quark and the beauty quark, the latter sometimes known as the bottom quark. In spite of their quaint names, these quarks have both played, and continue to play critical roles in particle physics research. The charm quark was the real spark for the acceptance of the whole picture of the quark-lepton sub-structure of matter. The bottom quark is now the focus of extensive studies around the world, studies which aim at understanding the details of standard-model CP violation and of the matter-antimatter asymmetry observed in experiments. More hopefully, these studies may find a glimpse of what lies beyond the standard model. Fermilab fixed-target experiments on particles containing charm quarks have provided guideposts in the understanding of CP violation. Given that the standard model explanation for the CP violation seen in the laboratory cannot explain the mysterious asymmetry in the matter-antimatter balance in the universe, there must be something beyond the standard model. Charm and beauty studies may hold the key to this and other tantalizing questions in particle physics. The mixing of charm particle and antiparticle, and the searches for rare and forbidden decays may open unexpected doors. Also, we may hope that a detailed study of physics involving charm and bottom quarks, when combined with the study of the other quarks, will lead to an understanding of why nature has arranged the quarks into three generations, with each generation containing two sometimes quite different quarks.

Even in the area of standard-model physics, there are important questions to which fixed-target experiments at Fermilab have contributed answers: how quarks are produced in high-energy interactions, how those quarks turn into the particles seen in the laboratory, and the dynamics leading to the decay of particles containing charm quarks. For example, since the charm and bottom quarks are produced dominantly by the fusion of bits of the glue that binds quarks within the particles that are seen directly in the laboratory, charm quark production properties may be used to study the distribution of the glue in particles. Also, the decay of charm particles provides a particularly clean environment in which to study the characteristics of those particles into which the charm particles decay. The recent charm experiments are providing answers that have eluded physicists for decades. The copious decays observed in Fermilab fixed-target experiments provide a unique way of studying the low-mass resonances of pairs of pions and of pions and kaons. These measurements complement those made historically in scattering experiments at lower energies.

Major contributions from the charm and beauty fixed target program also have been in the areas of detector development, and data acquisition and computing. The rarity of charm and beauty quarks in fixed target interactions and the unique decay properties of these quarks led experimenters to implement silicon microstrip detectors, trigger processors, fiber readout of scintillating plastics, high speed data readout, and web-based monitoring. Creativity, trying non-standard techniques, and diverse and innovative beams have marked this fixed target program. Each experiment tried a different wrinkle to advance the science.

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5.2 E400 - charmed particle production by neutrons

University of Bologna (Italy), University of Colorado, Fermi National Accelerator Laboratory, University of Illinois, INFN, Milano (Italy), University of Pavia (Italy), Yale University

E400 was designed to study the neutron production and properties of charm particles. E400 featured a novel, high resolution MWPC called the D5 to enable the experiment to tag charm particles through their very short, but finite lifetime. The D5 was a precursor to much finer pitched microstrip detectors which emerged in the next generation of charm experiments a few years later and revolutionized charm particle reconstruction in fixed target environments. E400 was able to confirm the first evidence for the existence of the X_c⁺ baryon, the first baryon observed that has both charm and strange quark content.

E400 also measured the X_c⁺ lifetime with greater precision than known previously. Another E400 highlight was the first observation of the neutral D meson decaying into a final state consisting of two K_s^o mesons. This is an especially interesting final state. It is not expected to occur directly because of an interesting cancellation of contributions. It is likely to be produced through final-state re-scattering in other, direct decays.

E400 Degree Recipients

F. Bossi Ph.D. University of Pavia

Janice Enagonio Ph.D. University of Colorado

John Eugene Filaseta Ph.D. University of Illinois at Urbana-Champaign

Thomas Knight Kroc Ph.D. University of Illinois at Urbana-Champaign

Raymond Ladbury Ph.D. University of Colorado

Calvin L. Shipbaugh Ph.D. University of Illinois at Urbana-Champaign

E400 Publications

Production of the charmed strange baryon X ⁺ by neutrons., P. Coteus et. al., Phys. Rev. Lett. 59, 1530 (1987).

Measurements of the S _c° - L _c⁺ and S _c ⁺- L _c ⁺ mass differences., M. Diesburg, et. al., Phys. Rev. Lett. 59, 2711 (1987).

The first observation of D° → K° anti-K°., J.P. Cumulat, et. al., Phys. Lett. B210, 253 (1988).

Production of the D_s^± by high energy neutrons., C. Shipbaugh, et. al., Phys. Rev. Lett. 60, 2117 (1988).

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5.3 E653 - Charm and Beauty Decays in a Hybrid Emulsion Spectrometer

Aichi (Japan), UC/Davis, Carnegie-Mellon, Chonnam National (Korea), Fermilab,

Gifu (Japan), Gyeongsang National (Korea), Joenbug (Korea), Kinki (Japan), Kobe

(Japan ), Korea (Korea), Nagoya (Japan), Nagoya Inst. of Tech. (Japan), Ohio State,

Okayama (Japan), Oklahoma, Osaka City (Japan), Osaka Sci. Ed. Center. (Japan),

Toho (Japan), Utsunomiya (Japan), Yokohama National (Japan), Won Kwang (Korea)

E653 studied short-lived charm and beauty particles produced by high-energy pion and proton beams. The experiment’s unique feature incorporated a hybrid of emulsion target and conventional spectrometer. Decay candidate events to be scanned in the emulsion were selected and located with a silicon microstrip vertex detector. The emulsion target allowed the chosen events to be examined with sub-micron resolution. E653 had exceptionally good muon identification, and used a muon trigger to enrich the recorded sample of beauty events and of semimuonic and purely muonic decays of charm. The experiment used nine fully-reconstructed beauty quark-antiquark pairs to study production properties at fixed-target energies and to measure beauty lifetimes. It made an excellent measurement of semileptonic decay form factors for D⁺ → anti-K*^o(892) m n_m , made the first observation of D⁺ → r m n_m , and the first form factor measurements for D_s⁺ → f m n_m. The experiment used its hybrid capabilities to full advantage to do physics otherwise inaccessible: good limits for flavor-changing neutral current decays of charm in multineutral modes, and for possible four- and five-body semileptonic decays of charm; and a study of D_s⁺ → m n_m. This very interesting purely leptonic decay is very difficult to study in conventional spectrometers because of its one-prong "kink" topology, but is ideally suited to E653's hybrid emulsion technique.

E653 Degree Recipients

T. Abe Ph.D. Kobe University

M. Adachi M.S. Toho University

James M. Dunlea Ph.D. Ohio State University

K. Ebara M.E. Utsunomiya University

Arne P. Freyberger Ph.D. Carnegie Melon University

K. Fujiwara M.S. Kobe University

O. Fukuda M.E. Utsunomiya University

K. Horie M.E. Utsunomiya University

S. Ikegami M.S. Toho University

N. Itou M.S. Kobe University

M. Kamiya M.E. Utsunomiya University

M. Komatsu M.S. Nagoya University

M. Komatsu Ph.D. Nagoya University

T. Koya M.S. Toho University

Akbar Mokhtarani Ph.D. University of California at Davis

William R. Nichols Ph.D. Carnegie Melon University

E. Niu M.S. Toho University

E. Niu Ph.D. Toho University

I. Ohtsuka M.E. Utsunomiya University

Gene A. Oleynik Ph.D. Ohio State University

Vittorio Paolone Ph.D. University of California at Davis

M. Seshimo M.E. Utsunomiya University

A. Suzuki M.S. Osaka City University

K. Suzuki M.E. Utsunomiya University

M. Takeda M.S. Kobe University

K. Taruma Ph.D. Kobe University

S. Torikai M.S. Aichi University of Education

K. Umemura M.S. Osaka City University

S. Watanabe M.S. Toho University

S. Watanabe Ph.D. Toho University

T. Watanabe M.S. Osaka City University

T. Watanabe Ph.D. Osaka City University

O'Hara Wilcox Ph.D. University of California at Davis

M. Yamaki M.E. Utsunomiya University

R. Yokomizo M.S. Osaka City University

S. Yoshida M.S. Nagoya University

S. Yoshida Ph.D. Nagoya University

Chong Zhang Ph.D. Carnegie Melon University

E653 Publications

Measurement of the Relative Branching Fraction G (D^o → K m n_m) / G (D^o → m X)., K. Kodama, et al., Phys. Rev. Lett. 66, 1819 (1991).

Charm Meson Production in 800 GeV/c Proton-Emulsion Interactions., K. Kodama, et al., Phys. Lett. B263, 573 (1991).

Charm Pair Correlations in 800 GeV/c Proton-Emulsion Interactions., K. Kodama, et al., Phys. Lett. B263, 579 (1991).

Charm Meson Production in 600 GeV/c p^- Interactions., K. Kodama, et al., Phys. Lett. B284, 461 (1992).

Measurement of the Form Factor Ratios in the Decay D⁺ → anti-K*^o(892) m⁺ n., K. Kodama, et al., Phys. Lett. B274, 246 (1992).

Measurement of the Branching Ratio for D⁺ → anti-K*^o(892) m⁺ n., K. Kodama, et al., Phys. Lett. B286, 187 (1992).

Measurement of the Lifetimes of Charged and Neutral Beauty Hadrons., K. Kodama, et al., Prog. Theo. Phys. 89, 679 (1993).

Measurement of Beauty Hadron Pair Production in 600 GeV/c p^- Emulsion Interactions., K. Kodama, et al., Phys. Lett. B303, 359 (1993).

A Study of Semimuonic Decays of the D_S,. K. Kodama, et al., Phys. Lett. B309, 483 (1993).

Limits for Four- and Five-Prong Semileptonic Charm Meson Decays., K. Kodama, et al., Phys. Lett. B313, 260 (1993).

Search for Diffractive Charm Production in 800 GeV/c Proton-Silicon Interactions., K. Kodama, et al., Phys. Lett. B316, 188 (1993).

Observation of D⁺→ r^o(770) m⁺ n., K. Kodama, et al., Phys. Lett. B316, 455 (1993).

Measurement of G ( D^o → K ^-m⁺ n) / G ( D^o → m⁺ X) using a D* tag., K. Kodama, et al., Phys. Lett. B336, 605 (1994).

Upper Limits for Charm Hadron Decays to Two Muons Plus a Hadron., K. Kodama, et al., Phys. Lett. B345, 85 (1995).

Direct Measurement of the Pseudoscalar Decay Constant of the D_., K. Kodama, et al., Phys. Lett. B382, 299 (1996).

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5.4 E672 - Hadronic Final States in Association with High Mass Dimuons

Fermilab, IHEP/Protvino (Russia), Illinois/Chicago,

Indiana, Louisville, Michigan/Flint

The production of beauty quarks in hadronic collisions is a subject of persistent theoretical and experimental interest. The comparison of the measured beauty-quark production cross section with the Next-to-Leading Order Quantum Chromodynamic (NLO QCD) calculations reveals the underlying dynamics. In addition to the lowest order beauty quark-antiquark pair production processes via gluon fusion or quark exchange, sizable contributions come from diagrams including the gluon exchanges with subsequent gluon splitting, and flavor excitation in which a gluon virtual fluctuation to a beauty quark-antiquark pair is put on-mass shell by an interaction. It is known that the measured inclusive beauty-quark cross sections at the Tevatron collider exceed the NLO QCD predictions by a factor of about 2.5 to 3. The NLO QCD calculations for the beauty quark-antiquark pair production are expected to be more reliable at fixed-target energies.

Renewed interest in the charmonium and bottomonium production originated with the observation by the CDF Collaboration that the direct J/y and y(2S) production exceeds expectations based on the color singlet model (CSM) of charmonium production by a factor of about 50. This observation led to a development of the color octet model (COM), nonperturbative parameters of which were fitted to match the CDF data. In the color singlet model, the charmonium meson retains the quantum numbers of the produced charm quark-antiquark pair, and thus each J/y state can only be directly produced via the corresponding hard scattering color singlet subprocess. The color octet mechanism extends the color singlet approach by taking into account the production of charm quark-antiquark pairs in a color octet configuration accompanied by a gluon. The color octet state evolves into a color singlet state via emission of a soft gluon. The inclusion of the color octet mechanism leads to a prediction that directly produced y charmonia will be increasingly transversely polarized at high transverse momentum. The polarization prediction is the most likely effect to help distinguish the COM model from the multiple soft gluon exchanges (color evaporation) model.

E672 was an open geometry experiment, the aim of which was to study hadronic processes yielding high-mass dimuons (the trigger) and associated particles, using proton and pion beams at momenta up to 800 GeV/c striking various nuclear targets. The specific goals, which are all related to experimental tests of Quantum Chromodynamics (QCD), included hadroproduction of: (i) beauty quarks observed through inclusive and exclusive decays to J/y, (ii) charmonium c_c states observed via their radiative decays into J/y g, and (iii) y(2S) states observed in its m⁺ m^- and J/y p⁺ p^- decay modes.

Experiment E672 shared the Meson West beamline and spectrometer with the experiment E706 studying direct photon production. The data from the two experiments were written to shared tapes, and then independently analyzed. Most of the E672 publications were joint publications with E706 colleagues.

E672 measured beauty-quark production in pion-beryllium collisions at 515 GeV/c by identifying events with J/y originating from secondary vertices. In addition to inclusive J/y + X decays, the experiment reported five events of exclusive J/y K or J/y K* decays. The measured cross section, although with a large uncertainty, indicated an excess of data over the theory predictions.

E672 studied charmonium production in pion-beryllium and proton-beryllium collisions at 515 GeV/c and 800 GeV/c. The results included differential J/y cross sections and fractions of J/y produced either directly or as products of y(2s) and radiative c₁ and c₂ states decays. The measured x_F distributions were used for an extensive comparison with the color-octet model predictions. All values of the required non-perturbative matrix elements were derived from other experiments, primarily from charmonium photoproduction data and from J/y production data from the Tevatron. In general, the parameter-free predictions of the model for x_F - distributions agree with the proton and pion induced data both in magnitude and shape. On the other hand, the E672 data are consistent with unpolarized J/y production, contrary to expectations from the color octet model, but in agreement with the color evaporation model.

In addition, E672 was one of the first experiments to analyze the absorption of J/y particles in nuclear matter.

In its earlier incarnation (1984), E672 was also concerned with the production of jets in 800 GeV/c proton-nucleus interactions. There are several reasons for studying such interactions. First, measurements of secondary particles produced in these processes can provide unique information about the space-time development of proton-nucleon interactions. The nucleus serves as a short-range detector which interferes with the intermediate hadronic state produced in the primary proton-nucleon interaction, before that state can materialize into the observed particles. Second, results from proton-nucleus interactions help in understanding the properties of nuclear matter at high energy densities, a topic of considerable interest for the current quark-gluon plasma investigations.

The E557/E672 trigger required a deposition of large transverse energy (E_T) in a large coverage calorimeter centered around 90 degrees in the proton-nucleon center of mass system. The experiment observed a nuclear enhancement in producing events with large E_T and studied its dependence on the event topology. We were also able to separate effects associated with the jet production from nuclei.

E672 Degree Recipients

Paul Draper Ph.D. Indiana University

Richard Jesik Ph.D. University of Illinois at Chicago Circle

Subramanian Kartik Ph.D. Indiana University

Rui Li Ph.D. Indiana University

Sheila Markham M.S. Indiana University

Aditya K. Sambamurti Ph.D. Indiana University

Donald A. Stewart Jr. Ph.D. Indiana University

Francisco Vaca Ph.D. University of Illinois at Chicago Circle

Guan Wu Ph.D. University of Illinois at Chicago Circle

E557/E672 Publications

A Measurement of Nuclear Enhancement in High-E_T and Jet Event Production., R. Gomez, et al., Phys Rev. D35, 2736 (1987).

A Dependence of Highly Inelastic p Nucleus Collisions., A. Sambamurti, et al., Phys Rev D41, 1371(1990).
Production of High p_t Jets in proton-Nucleus Collisions., D. Stewart, et al., Phys Rev. D42, 11 (1990).
A Dependence of J/y Production in p^- Nucleus Collisions at 530 Gev/c., S. Kartik, et al., Phys. Rev. D41, 1 (1990).

E672/E706 Publications

Bottom Production in p^- Be at 515 GeV/c., R. Jesik, et al., Phys. Rev. Letters 74, 495 (1995). J/y and y(2s) Production in p^- Be at 515 GeV/c., A. Gribushin, et al., Phys. Rev. D53, 4723 (1996).
Production of Charmonium States in p^- Be at 515 GeV/c., V. Koreshev, et al., Phys. Rev. Letters, 77, 4294 (1996).

Differential Cross Sections of J/y in p Be Collisions at 530 and 800 GeV/c., A. Gribushin, et al., Phys. Rev. D61, 1120XX (2000).

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5.5 E687 - Photoproduction of Charm and Beauty

INFN/Bologna (Italy), UC/Davis, Colorado, Fermilab, INFN/Frascati (Italy),

Illinois, Korea (Korea), INFN/Milano (Italy), Milano (Italy), North Carolina,

Northwestern, Notre Dame, Pavia (Italy), Puerto Rico/Mayaguez,

South Carolina, Tennessee, Western Kentucky, Vanderbilt

Experiment E687 was an experiment studying the production and decay of charm particles in the Wideband Photon Beam in the Proton Area. The spectrometer was based on two large analysis magnets, which provided a large charged particle acceptance covering the entire forward hemisphere. The spectrometer was instrumented with twelve planes of silicon microstrip detectors, totaling 8256 pulse height analyzed strips, which provided primary and secondary vertex reconstruction; three threshold Cerenkov counters of about 100 cells each to provide charged hadron identification; a 10 meter neutral Vee decay volume; small and wide angle electromagnetic calorimeters providing excellent g and p^o identification; and muon identification based on scintillators and proportional tubes. Hadron calorimeters permit one to trigger on photoproduced events with hadrons in the final state.

The E687 Collaboration had three data-taking periods. The first occurred from December 1987- February 1988. During this period a total of 60 million triggers were written on tape. The second running period was from March 1990 until August 1990, when 300 million events were accumulated. The third running period began in June 1991 and lasted until January 1992. During this third running period we accumulated another 200 million triggers giving the experiment a total of 500 million triggers for the 1990-1991 running period.

This experiment had many important results, including obtaining the best lifetime measurements for all of the weakly decaying charm particles, D⁺, D^o, D_s, L_c, X_c⁺ ; the discovery of the W_c^o ; charm baryon and measurement of its lifetime; and detailed study of the semileptonic form factors of D^o, D⁺, and D_s. Many of the measurements made by the E687 collaboration remain as the defining numbers in the compilations of the Particle Data Group.

E687 Degree Recipients

Vicenzo Arena Ph.D. University of Pavia

Stefano Bianco Ph.D. University of Roma

Kathleen Danyo Blackett Ph.D. University of Tennessee

Gavin Reed Blackett Ph.D. University of Tennessee

Christopher W. Bogart Ph.D. University of Colorado

Germano Bonomi Ph.D. University of Pavia

Barbara Caccianiga Ph.D. University of Milano

Jianwei Cao Ph.D. Vanderbilt University

Byungu Cheon Ph.D. Korea University

I. Chini Ph.D. University of Milano

Yeonsei Chung Ph.D. Korea University

Luca Cinquini Ph.D. University of Colorado

Daniel R. Claes Ph.D. Northwestern University

Raymond Lloyd Culbertson Ph.D. University of Illinois at Urbana-Champaign

Steven W. Culy Ph.D. University of Colorado

John DeAndrea Cunningham Ph.D. Notre Dame University

Carlo James Dallapiccola Ph.D. University of Colorado

Kathy Danyo Ph.D. University of Tennessee

Renato Diaferia Ph.D. University of Pavia

Gabriele Feretti Ph.D. University of Pavia

Robert William Jr. Gardner Ph.D. Notre Dame University

Marco Giammarchi Ph.D. University of Milano

Gabriele Gianini Ph.D. University of Pavia

Rodney Lennart Greene Ph.D. University of Illinois at Urbana-Champaign

Gary Grim Ph.D. University of California at Davis

David Hazan Ph.D. University of Milano

Glen Richard Jaross Ph.D. University of Illinois at Urbana-Champaign

Will E. Johns Ph.D. University of Colorado

Christopher John Kennedy Ph.D. Notre Dame University

K.Y. Kim Ph.D. Korea University

K.B. Lee Ph.D. Korea University

Franco Leveraro Ph.D. University of Milano

Tzu-Fen Lin Ph.D. Notre Dame University

Karen Lynette Lingel Ph.D. University of Illinois at Urbana-Champaign

Sandra Malvezzi Ph.D. University of Milano

Eric James Mannel Ph.D. Notre Dame University

Hector Mendez Ph.D. Cinvestav

Ray Mountain Ph.D. Notre Dame University

Matthew S. Nehring Ph.D. University of Colorado

Brian O'Reilly Ph.D. Northwestern University

Seongwan Park Ph.D. Northwestern University

C. Pezzani Ph.D. University of Milano

Murali Pisharody Ph.D. University of Tennessee

Danilo Ljubisav Puseljic Ph.D. Notre Dame University

Cristina Riccardi Ph.D. University of Pavia

Joseph Alexander Swiatek Ph.D. Notre Dame University

Donatella Torretta Ph.D. University of Milano

Paolo Vitulo Ph.D. University of Pavia

Ze-yuan Wu Ph.D. Notre Dame University

Rikutaro Yoshida Ph.D. Northwestern University

Manuel Eugenio Zanabria Ph.D. Notre Dame University

E687 Publications:

Measurement of the L_c and D_s⁺ Lifetimes., P.L. Frabetti, et al., Phys. Lett. B251, 639 (1990).

A Measurement of the D^o and D⁺ Lifetimes., P.L. Frabetti, et al., Phys. Lett. B263, 584 (1991).

Measurement of the decays D^o → p⁺p⁺p^-p^-, D^o → K^- K⁺, and D_s⁺ → f p⁺p⁺p^-., P.L. Frabetti, et al., Phys. Lett. B281, 167 (1992).

Study of D^o →K_s^o p⁺ p^-and D^o → K_s^o K^- K⁺, in High Energy Photoproduction., P.L. Frabetti, et al., Phys. Lett. B286, 195 (1992).

First Observation of W_c → W^- p^+., P.L. Frabetti, et al., Phys. Lett. B300, 190 (1993)

A Measurement of the L_c⁺ Lifetime., P.L. Frabetti, et al., Physical Review Letters 70, 1755 (1993).

Measurement of Mass and Lifetime of the X_c⁺., P.L. Frabetti, et al., Physical Review Letters 70, 1381 (1993) .

Measurement of the Lifetime of the X_c^o., P.L. Frabetti, et al., Physical Review Letters 70, 2058 (1993).

Analysis of the Decay Mode D⁺ → anti-K*^o m⁺ n., P.L. Frabetti, et al., Phys. Lett. B307, 262 (1993).

Studies of D anti-D Correlations in High Energy Photoproduction., P.L. Frabetti, et al., Phys. Lett. B308, 193 (1993).

Precise Measurement of the D_s⁺ Meson Lifetime., P.L. Frabetti, et al., Physics Review Letters 71, p.827 (1993).

A Measurement of G (D_s⁺ → f m⁺n)/G ( D_s⁺ → f p⁺)., P.L. Frabetti, et al., Phys. Lett. B313, 253 (1993).

Evidence of the Cabibbo-Suppressed decay L_c⁺ → p K^- K⁺., P.L. Frabetti, et al., Phys. Lett. B314, 477 (1993).

Study of D^o → K^-m⁺n in High Energy Photoproduction., P.L. Frabetti, et al., accepted Phys. Lett. B315, 203 (1993).

Measurement of the Masses and Widths of L=1 Charmed Mesons., P.L. Frabetti, et al., Phys. Rev. Lett. 72, 324 (1994)

An observation of an Excited State of the L_c⁺ Baryon., P.L. Frabetti, et al., Phys.Rev. Lett. 72, 961 (1994).

A Measurement of the Cabibbo-Suppressed Decays D^o → p^-p⁺ and D^o → K ^-K⁺., P.L. Frabetti, et al., Phys. Lett. B321, 295 (1994).

Precise Measurements of the D^o and D⁺ Meson Lifetimes., P.L. Frabetti, et al., Phys. Lett. B323, 459 (1994).

Measurement of the Form Factors for the Decay D_s⁺ → f m⁺n., P.L. Frabetti, et al., Phys. Lett. B328,184 (1994).

Analysis of Three D → K p p Dalitz Plots., P.L. Frabetti, et al., Phys. Lett. 331, 217

Search for CP Violation in Charm Meson Decay., P.L. Frabetti, et al., Physics Rev. D50, 2953 (1994).

First Observation of the S^-p⁺ p⁺ decay mode of the L_c baryon and its branching ratio relative to the S⁺ p⁺ p^- mode., P.L. Frabetti, et al., Phys. Lett. B328, 193 (1994).

Observation and Mass Measurement of W_c^o→ S⁺ K^-K^-p⁺., P.L.Frabetti, et al., Phys. Lett. 338, 106 (1994).

Branching Ratios of the decays D^o → K_s^o K_s^o and D^o → K_s^o K_s^o K_s^o., P.L. Frabetti, et al., Phys. Lett. 340, 254 (1994).

Charm Meson Decay into the Final States K_s^o K⁺ and K_s^o K*⁺., P.L. Frabetti, et al., Phys. Lett. 346, 199 (1995).

Analysis of the D⁺, D_s⁺ → K⁺K^-p⁺ Dalitz Plots., P.L. Frabetti, et al., Phys. Lett. 351, 591 (1995).

Study of charged four-body decays of the D^o meson., P.L. Frabetti, et al., Phys. Lett. 354, 486 (1995).

First measurement of the lifetime of the W_c^o., P.L. Frabetti, et al., Phys. Lett. 357, 678 (1995).

Doubly and singly Cabibbo suppressed charm decays into the K⁺ p⁺ p^- final state., P.L. Frabetti, et al., Phys. Lett. 359, 403 (1995).

Search for the Decay of D⁺ and D_s⁺ Mesons to Three Charged Kaons., P.L. Frabetti, et al., Phys. Lett. 363, 259 (1995).

Analysis of the Decay Mode D^o → K ^-m⁺n_m., P.L. Frabetti, et al., Phys. Lett. 364, 127 (1995).

Measurement of Photoproduction Cross Sections for Charmed Baryons Decaying to L_c⁺., P.L. Frabetti, et al., Phys. Lett. 365, 461 (1996).

Charm-Anticharm Asymmetries in High Energy Photoproduction., P.L. Frabetti, et al., Phys. Lett. 370, 222 (1996).

Analysis of the Cabibbo Suppresed Decay D⁺ → p^-e⁺n., P.L. Frabetti, et al., Phys. Lett. 382 312 (1996).

Observation of the vector meson Cabibbo Suppresed Decay D⁺→ r^om⁺n., P.L. Frabetti, et al., Phys. Lett. 391, 235 (1997).

Search for Rare and Forbidden Semileptonic Decays of the Charmed Meson D⁺., P.L. Frabetti, et al., Phys. Lett. B401, 131 (1997).

Five body decays of the D⁺ and D_s⁺., P.L. Frabetti, et al., Phys. Lett. B398, 239 (1997).

Three p Dalitz Analysis., P.L. Frabetti, et al., Phys. Lett. B407, 79 (1997).

A New Measurement of the Lifetime of the X_c⁺., P.L. Frabetti, et al., Phys.Lett. B427, 211 (1998).

Observation of a Narrow State Decaying to X_c^o p⁺., P.L. Frabetti, et al., Phys. Lett. B426, 403 (1998).

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5.6 E691 - Charm Production with the Tagged Photon Spectrometer

UC/Santa Barbara, Carleton (Canada), CBPF (Brazil), Colorado, Fermilab,

NRC (Canada), Oklahoma, Sao Paulo (Brazil), Toronto (Canada)

E691 was the first experiment to clearly establish the power of fixed target experiments in the study of heavy quark physics. The 100 million event data set led to physics publications using over ten thousand reconstructed charm decays. Many of the measurements from this charm quark experiment dominated the world averages of relevant parameters for over a decade. The measurements of charm particle lifetimes, which were among the first results published by the experiment, genuinely established the reputation of the experiment. Later papers in refereed journals covered topics relating to tests of the Standard Model, determination of the mechanisms of the electroweak decay of charm particles, QCD measurements, etc.

The first publication from E-691 was of the A-dependence of J/y photoproduction. This data was taken in a special closed geometry period at the end of the run. Precision measurements of the lifetimes of charm mesons and the lowest mass charm baryon, from data taken with the standard open geometry spectrometer used during most of the run, followed soon after. These lifetime measurements, along with a wealth of branching ratios, serve as the basis of understanding the dynamics of charm quark decay, selecting among spectator, W exchange, annihilation and penguin theoretical diagrams in the hadronic decay sector. The measurements in the semileptonic domain include the first full Dalitz plot analysis in terms of all the kinematic variables available. This became possible only with the size of the data set and good signal to background results obtained after event selection. Tests of the Standard Model have included searches for D^o anti-D^o mixing and flavor changing neutral currents in leptonic decays of D^o's.

The most copious signals were used to study the charm production mechanism, dominated by photon-gluon fusion. The data, interpreted with next to leading order calculations recently available, led to determination of such fundamental parameters as the mass of the charm quark and the most direct determination of the distribution of gluons in nucleons.

E691 was the first Tevatron experiment using the Tagged Photon Spectrometer (TPS), a multi-stage full acceptance detector with precision determination of charged particle tracks and particle identification. The TPS tracking had been specially upgraded for E691 with the introduction of nine silicon microstrip detectors downstream of the 5 cm beryllium target. These detectors, each with 50 micron-wide detector elements, supplied the capability of resolving the decay vertex from the primary production point of long-lived charm particles. This permitted events with charm particles to be selected from the much more copious, but less interesting background events. In addition, by using only those tracks which came from the decay vertex, the combinatoric background was enormously reduced.

The trigger for the experiment was a very general high-Et trigger. This allowed accumulation of data for the wide variety of physics which has come out of the experiment. The Tevatron itself provided upgraded capability relative to earlier experiments. The higher energy allowed greater photon fluxes in the incident beam and the improved spill duty factor (longer beam availability times) allowed collection of the unprecedented amount of data. Finally, the experiment benefited from the availability of the first parallel processing computing system applied to a Fermilab experiment. This system incorporated home-built (non-commercial), single-board computers (the first ACP farms). Use of this system significantly sped up the reconstruction of raw data to allow early results with the full data set.

E691 pioneered techniques which have since become standard in a very broad range of high energy physics experiments, especially the use of silicon microstrip detectors in Fermilab experiments and of parallel processing for off-line reconstruction of data.

E691 Degree Recipients

Thomas Earl Browder Ph.D. University of California at Santa Barbara

Jean Etienne Duboscq Ph.D. University of California at Santa Barbara

Mark Gibney Ph.D. University of Colorado

Jenny Huber Ph.D. University of California at Santa Barbara

Jose Guilherme Lima M.S. Centro Brasileiro de Pesquisas Fisicas

Scott Menary Ph.D. University of Toronto

Gregory Dean Punkar Ph.D. University of California at Santa Barbara

Johannes Rudolf Raab Ph.D. University of California at Santa Barbara

William Robert Ross Ph.D. Yale University

David Schmidt Ph.D. University of California at Santa Barbara

Anthony Lee Shoup Ph.D. University of Cincinnati

Daniel James Sperka Ph.D. University of California at Santa Barbara

Audrius Stundzia Ph.D. University of Toronto

E691 Publications

An Experimental Study of the A-Dependence of J/y Photoproduction., M.D.Sokoloff, et al., Phys. Rev. Lett. 57, 3003 (1986).

Measurement of the D⁺ and D^o Lifetimes., J.C. Anjos, et al. Phys. Rev.Lett. 58, 311 (1987).

Measurement of the D_s⁺ Lifetimes, J.C. Anjos, et al., Phys. Rev. Lett. 58, 1818 (1987).

Measurement of D_s^± Decays and Cabibbo-Suppressed D^± Decays, J.C. Anjos, et al., Phys. Rev. Lett. 60, 897 (1988).

A Study of D^o anti-D^o Mixing., J.C. Anjos, et al., Phys. Rev. Lett. 60,1239 (1988).

Measurement of the L _s⁺ Lifetime., J.C. Anjos, et al., Phys. Rev. Lett. 60, 1379 (1988).

Measurement of the D^o, D⁺ and D_s⁺ Lifetimes., J.R. Raab, et al., Phys. Rev. D37, 2391 (1988).

Measurement of D_s^± and D^± Decays to Nonstrange States, J.C. Anjos, et al., Phys. Rev. Lett. 62, 125 (1989).

Charm Photoproduction., J.C. Anjos, et al.,, Phys. Rev. Lett. 62, 513 (1989).

Experimental Study of the Semileptonic Decay D⁺ → K*^oe⁺n_e, J.C. Anjos, et al.,, Phys. Rev. Lett. 62, 722 (1989).

A Study of the Semileptonic Decay Mode D^o → K ^-e⁺n_e, J.C. Anjos, et al., Phys. Rev. Lett. 62, 1587 (1989).

Observation of Excited Charmed Mesons., J.C. Anjos, et al., Phys. Rev. Lett. 62, 1717 (1989).

Observation of S_c^o→ L_c⁺ p^- Decays., J.C. Anjos, et al., Phys. Rev. Lett. 62, 1721 (1989).

A Study of D_s^± and D^± Decays into Four-Body Final States Including h p^± and w p^±., J.C. Anjos, et al., Phys. Lett. B223, 267 (1989).

A Study of Decays of the L _s⁺, J.C. Anjos, et al., Phys. Rev. D41, 801 (1990).

Study of D_s⁺ → f e⁺ n_e and the Absolute D_s⁺→ f p⁺ BranchingFraction., J.C. Anjos, et al.,, Phys. Rev. Lett. 64, 2885 (1990).

Study of the Decays D⁺ → K^o p⁺ and D⁺ → K^o K⁺, J.C. Anjos et al.,, Phys. Rev. D41, 2705 (1990).

Photon-Gluon Fusion Analysis of Charm Photoproduction., J.C. Anjos, et al.,, Phys. Rev. Lett. 65, 2503 (1990).

Measurement of the Form-Factors in the Decay D⁺ → anti-K*^o e⁺n_e , J.C. Anjos, et al.,, Phys. Rev. Lett. 65, 2630 (1990).

Experimental Results on the Decays D → Kpppp., J.C. Anjos et al.,, Phys. Rev. D42, 2414 (1990).

Some Cabibbo-Suppressed Decays of the D^o Meson., J.C. Anjos et al.,, Phys. Rev. D43, R635 (1991).

Study of the Decay D_s⁺ → h' p⁺, J. C. Anjos, et al.,, Phys. Rev. D43, 2063 (1991).

A Study of the Decay D⁺ → K ^o e⁺ n_e, J. C. Anjos, et al.,, Phys. Rev. Lett. 67, 1507 (1991).

Measurement of the Decays D^o → p^- p⁺ and D^o → K^- K⁺, J.C. Anjos, et al.,, Phys. Rev. D44, 3371 (1991).

Study of the Doubly Cabibbo-Suppressed Decay D⁺ → f K⁺ and the Singly Cabibbo-Suppressed Decay D_s⁺ → f K⁺, J.C. Anjos, et al.,, Phys. Rev. Lett. 69, 2892 (1992).

Experimental Probes of Final State Interactions in D^o Meson Decays, J. C. Anjos, et al.,, Phys. Rev. D46, 1 (1992).

Study of the Decays D → Kppp, J.C. Anjos, et al.,, Phys. Rev. D46, 1941 (1992).

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5.7 E743 - charm production in pp collisions with lebc-fmps

Achen (German),ihep / berlin (Germany), CERN (Switzerland). Strasbourg (France), Dunke, Fermilab, Flordia State, Kansas, L’Etat (Belgium), Libre (Belgium), LPNHE (France), Michigan State, Northeastern, Notre Dame, Tata (India), Vanderbilt, Vienna (Austria)

The small liquid hydrogen bubble chamber LEBC was specially designed for the study of charm particle properties in the fixed target environment. The conventional optical system of LEBC provided a resolved bubble diameter of 20 microns which yielded a high efficiency for the detection of both production and decay vertices of the charm particles. LEBC was built at CERN and first used there with the European Hybrid Spectrometer in experiments with 360 GeV/c pion and 400 GeV/c proton beams.

Charm production was an exciting research topic in the early eighties. CERN experiments using the ISR were obtaining indirect evidence for charm hadroproduction and their attempts at cross section determinations yielded values between ten and a hundred times larger than those of the LEBC experiment. Was there a threshold for new physics between the LEBC and ISR energies? The Fermilab Tevatron 800 GeV proton beams gave a natural way to investigate the issue. An 800 GeV proton beam colliding with a proton at rest gives a center-of-mass energy half way between the LEBC 400 GeV pp data and the ISR colliding-beam data, and it was therefore decided to propose an experiment at Fermilab using LEBC married to a suitable Fermilab spectrometer. Of course, this was a lot easier said than done!

LEBC was a plastic disposable bubble chamber occupying about a cubic foot of space and it was easy to bring LEBC to Fermilab for the PAC presentation in 1983. "At last a table-top particle physics experiment," said Leon Lederman, and the experiment was rapidly approved. The Fermilab MPS spectrometer was chosen for downstream particle identification and momentum determination. Several tons of equipment and a team of European technicians and engineers arrived from CERN, and it was quite a challenge to have everything up and running for the Tevatron start-up in 1985. Some of the more unexpected problems encountered by the collaboration included living creatures in the Casey's pond cooling water, spilled liquids on the scanning table causing experimenters to stick to the table top in their eagerness to find charm events, but great excitement over all.

By all measures, the experiment was a success. Almost 1.2 million triggers were recorded, corresponding to 0.5 million pp interactions in the visible region of the liquid hydrogen. More than a hundred charm event candidates were discovered and these were used to measure charm production characteristics. These results supported the CERN LEBC results and indicated problems with the ISR data. All results were in good agreement with the QCD-based fusion model.

Finally, a comparison of the production characteristics of charm events in the hadroproduced CERN and Fermilab data were used to give a somewhat controversial determination of the charm quark mass.

The experiment was a huge amount of fun, didn't cost much, and produced valuable physics results. What more can one ask for?

E743 Degree Recipients

Gay E. Canough Ph.D. Notre Dame University

T.O. Dershem Ph.D. University of Michigan

C. Hamilton Ph.D. Northeastern University

Xiao D.James Liu Ph.D. University Kansas

G.E. Mendez Ph.D. Duke University

Ai Gia Nguyen Ph.D. Michigan State University

A. Roth Ph.D. Aachen University

Mark Frederick Senko Ph.D. Vanderbilt University

B. Vonck Ph.D. Brussels University

Michael F. Weber Ph.D. University of Michigan

C.F. Wild Ph.D. Duke University

Christos Zabounidis Ph.D. Northeastern University

E743 Publications

D-Meson Production in 800 GeV/c p p Interactions., R. Ammar, et al., Phys.Rev.Lett. 61, 2185 (1988).

Inclusive Charm Cross-Sections in 800 GeV/c p p Interactions., R. Ammar, et al., Phys.Lett. B183, 110 (1987).

Multiplicity of Charged Particles in 800 GeV/c p p Interactions., R. Ammar, et al., Phys.Lett. B178, 124 (1986).

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5.8 E769 - Hadroproduction of charm

CBPF (Brazil), Fermilab, University of Mississippi, Northeastern University,University of Toronto (Canada), Tufts University, University of Wisconsin - Madison, Yale University

In interactions involving hadrons such as pions, kaons, and protons, the production of charm particles arises dominantly from the fusion of the glue that holds the incident hadrons together. Thus, by studying the charm production process itself, we have obtained information about the glue inside pions, kaons, and protons. E769 demonstrated conclusively, that the glue in mesons, pions and kaons, is distributed differently from that in protons. The glue in mesons is "harder" than it is on average in protons. This might be expected since the glue in mesons binds a quark and an antiquark together, whereas in protons, the glue must be spread among three quarks.

E769 successfully applied, for the first time, the tools which had been used so effectively in the previous charm quark experiment with photon beams, to the hadron beam environment. Those tools included "silicon microstrip detectors" placed very close to the experiment production target for precise determination of the trajectories of charged particles and the separation of events with charm particles from the thousand-times more copious less-interesting interactions. Secondly, recently-available new computing technologies were applied to what were at the time revolutionary amounts of data. These technologies involved the application of parallel processing in both data acquisition and off-line data processing. E769 additions which were specially relevant for this hadron-beam experiment were two devices, each sensitive to a different kind of light emitted when beam particles passed through particular kinds of material. These devices were used to identify the incident beam particles as pions, kaons, or protons one-by-one. The two kinds of light are called transition radiation and Cerenkov radiation. The use of all these techniques together allowed E769 to study the production of charm particles by identified mesons and protons in the incident beam, thereby obtaining new results on both the charm particles and the internal structure of the beam particles themselves.

Another example of the kind of information coming from E769 measurements is how quarks produced in high-energy interactions evolve into the particles that are seen in the laboratory. This process, called "fragmentation" and "hadronization", can be understood by studying the regularities and differences among the types of charm particles and anti-particles as they are produced by the pions, kaons and protons.

E769 has shown evidence in several forms for the linkages among the quarks, both charm and more copious varieties, as the evolution unfolds in space and time.

E769 Degree Recipients

Gilvan Alves Ph.D. Centro Brasileiro de Pesquisas Fisicas

Sandra Amato Ph.D. Centro Brasileiro de Pesquisas Fisicas

Juan Astorga Ph.D. Tufts University

W. David Dagenhart Ph.D. Tufts University

Chris Darling Ph.D. Yale University

Pauline Gagnon Ph.D. University of California at Santa Cruz

Miriam Gandelman M.S. Centro Brasileiro de Pesquisas Fisicas

Colin Gay Ph.D. University of Toronto

Robert Jedicke Ph.D. University of Toronto

Jussara Miranda Ph.D. Centro Brasileiro de Pesquisas Fisicas

Helio da Motta Ph.D. Centro Brasileiro de Pesquisas Fisicas

Joao R.T. de Mello Neto Ph.D. Centro Brasileiro de Pesquisas Fisicas

David Passmore Ph.D. Tufts University

Ali Rafatian Ph.D. University of Mississippi

Alberto Reis Ph.D. Centro Brasileiro de Pesquisas Fisicas

Steve Takach Ph.D. Yale University

Dror Trumer M.S. Tel Aviv University

Andrew Wallace Ph.D. Yale University

Zhongxin Wu Ph.D. Yale University

E769 Publications

Feynman-x and Transverse Momentum Dependence of D^± and D^o, anti-D^o Production in 250 GeV p^--Nucleon Interactions, G.A. Alves, et al., Phys. Rev. Lett. 69, 3147 (1992).

Atomic Mass Dependence of D^± and D^o, anti-D^o Production in 250 GeV p^±Nucleon Interactions, G.A. Alves, et al., Phys. Rev. Lett. 70, 722 (1993).

Enhanced Leading Production of D^± and D*^± in 250 GeV p^±-Nucleon Interactions, G.A. Alves, et al., Phys. Rev. Lett. 72, 812 (1994).

D*^± production in 250 GeV p^±-Nucleon Interactions, G.A. Alves, et al., Phys. Rev. D49, R4317 (1994).

Forward Cross Sections for Production of D⁺, D^o, D_s, D*⁺, and L_c in 250 GeV p^±, K^±, and p Interactions with Nuclei, G.A. Alves, et al., Phys. Rev. Lett. 77, 2388 (1996). Erratum: Phys. Rev. Lett. 81, 1537 (1998).

Feynman-x and Transverse Momentum Dependence of D Meson Production in 250 GeV p, K, and p Interactions with Nuclei, G.A. Alves, et al., Phys. Rev. Lett. 77, 2392 (1996).

Atomic mass dependence of X ^- and anti-X ⁺ production in central 250 GeV p^--nucleon inter-actions, G.A. Alves, et al., Phys. Rev. D56, 6003 (1997).

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5.9 E771 - Beauty Production by Protons

Athens (Greece), Brown, UC/Berkeley, UCLA, Duke, Fermilab, Houston,

JINR (Russia), Lecce (Italy), MIT, McGill (Canada), Nanjing (PRC),

Northwestern, Pavia (Italy), Pennsylvania, Prairie View A&M, Shandong (PRC),

South Alabama, SSCL, Vanier (Canada), Virginia, Wisconsin

The last experiment in a Proton Area High Intensity Laboratory sequence was E771. This experiment was designed to detect the production of mesons containing beauty quarks. The beauty (or bottom) equivalent of charmonium, bottomonium or upsilon, had been discovered at Fermilab in the late 70's, but, at the time E771 was being planned, hardly any information was available on the production of mesons containing a beauty quark together with a light (up or down) quark. E771 was designed to observe the production of such particles (B-mesons) via their decays into J/y or into two muons (plus other particles). Such a study would shed light on various aspects of QCD. B-meson production occurs in approximately one out of a million interactions of a high energy beam with a target, and a further suppression in the amount of collectable events is caused by the small probability of a B-meson decaying into an easily identified final state (e.g. the one containing two muons). The main result of the experiment was to measure the cross section (i.e. the rate) of B-meson production by 800 GeV protons. Another product of the experiment was to set the best limit for an extremely rare process, "Flavor Changing Neutral Currents", whose observation would clarify fundamental aspects of the weak nuclear force (which is responsible for radioactive beta decay, or, more in general, for the transmutations among quarks of different flavors).

This beauty experiment was made feasible by the increase in energy of the Fermilab accelerator in the early 1980's from 400 to 800 GeV, which made possible the special high intensity secondary beam that was used for E771.

E771 Degree Recipients

Alan Blankman Ph.D. University of Pennsylvania

Andrew Boden Ph.D. University of California at Los Angeles

Germano Bonomi Laurea University of Pavia

Casey Durandet Ph.D. University of Wisconsin

Valerio Elia Laurea University of Lecce

Elena Evangelista Laurea University of Lecce

Karla Hagan Ph.D. University of Virginia

Pierrick Hanlet Ph.D. University of Virginia

Gianluca Introzzi Dottorato University of Pavia

Alexander Ledovskoy Ph.D. University of Virginia

Guanghui Mo Ph.D. University of Houston

Marco Panareo Dottorato University of Bari

Sathyadev Ramachandran Ph.D. University of California at Los Angeles

E771 Publications

Production of J/y, y’ and Upsilon in 800 GeV/c Proton-Silicon Interactions., T. Alexopoulos, et al., Phys. Lett. B374, 271 (1996).

Search for the Flavor Changing Neutral Current Decay D^o → m⁺m ^- in 800 GeV/c Proton-Si Interactions., T. Alexopoulos, et al., Phys. Rev. Lett. 77, 2380 (1996).

Differential Cross Sections of J/y and y’ in 800 GeV/c p Si Interactions., T. Alexopoulos, et al., Physical Review D55, 3927 (1997).

A Measurement of the b anti-b Cross Section in 800 GeV/c Proton-Silicon Interactions., T. Alexopoulos, et al., Phys. Rev. Lett. 82, 41 (1999).

A Study of Neutral Strange Particle Production in p N Interactions at sqrt{s} = 38 GeV., T. Alexopoulos, et al.,, submitted to Physical Review D, (1999).

A Measurement of c Production in 800 GeV/c p N Interactions., K. Hagan, et al.,, submitted to Physical Review D, (1999).

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5.10 E781/SELEX - Study of Charm Baryon Physics

Bogazici (Turkey), Bristol (United Kingdom), Carnegie-Mellon, CBPF (Brazil),

Fermilab, Hawaii, IHEP/Beijing (China), IHEP/Protvino (Russia), Iowa,

ITEP (Russia), Moscow State (Russia), MPI/Heidelberg (Germany), Paraiba (Brazil),

PNPI (Russia), Rochester, INFN/Rome (Italy), Rome (Italy), San Luis Potosi (Mexico),

Sao Paulo (Brazil), Tel Aviv (Israel), INFN/Trieste (Italy), Trieste (Italy)

E781/SELEX was a successor to the charged hyperon experiments E715 and E761. The collaboration was built on the charge hyperon collaboration from these experiments plus parts of E653 charm collaboration. E781/SELEX extended the definition of hyperon a bit to include strange baryons which also have charm quarks. The connection is two fold, since we've used the 600 GeV/c hyperon beam (half S‾ !) to produce the charm particles, hoping to enhance the number of strange-charmed states. The detector was a state of the art spectrometer with a high precision micro-vertex detector and first class particle ID from a photo-tube based Ring Imaging Cherenkov counter and TRDs to detect charm states with lifetimes as short as 1/25 of a B meson (~60 fsec).

The strange-charmed baryons X_c⁺(csu), X_c⁰(csd) and W_c⁰(css) are, even today, relatively unexplored territory. There are only 750 events in the Particle Data Book for all modes of all three states, in all experiments. E781/SELEX will help to change this with larger samples of cleaner events. Our initial charmed baryon paper is the first observation of a Cabibbo suppressed decay mode X_c⁺ → pK‾p⁺ with a total of 260 events in 3 modes. We will measure the lifetimes of all 7 weakly decaying charmed particles along with many of their production and decay properties. There is also a broad program of non-charmed physics in E781/SELEX ranging from measurements of the total scattering cross section and electro-magnetic radius of the S^- thru searches for various exotica like pentaquark states.

E781 Degree Recipients

Ana Lucia Ferreira de Barros M.S. Centro Brasileiro de Pesquisas Fisicas

Uwe Dersch Ph.D. Max-Planck-Institut Fur Kernphysik

Guido Dirkes M.S. Max-Planck-Institut Fur Kernphysik

Emrullah Durucan M.S. Max-Planck-Institut Fur Kernphysik

Ivo Eschrich Ph.D. Max-Planck-Institut Fur Kernphysik

Ricardo L. Fernandez M.S. Universidad Autonoma de San Luis Potosi

Marc-Andre Funk M.S. Max-Planck-Institut Fur Kernphysik

Fernanda G. Garcia M.S. University of Sao Paulo

Fernanda G. Garcia Ph.D. University of Sao Paulo

Igor Giller M.S. Tel Aviv University

Mithat Kaya M.S. University of Iowa

Henning Kruger M.S. Max-Planck-Institut Fur Kernphysik

Henning Kruger Ph.D. Max-Planck-Institut Fur Kernphysik

Prakash Mathew Ph.D. Carnegie Mellon University

Dirk Meier M.S. Max-Planck-Institut Fur Kernphysik

Kenneth D. Nelson Ph.D. University of Iowa

Erdogan Ozel M.S. University of Iowa

Pavel Pogodin Ph.D. University of Iowa

Jurgen Simon M.S. Max-Planck-Institut Fur Kernphysik

Jurgen Simon Ph.D. Max-Planck-Institut Fur Kernphysik

Klaus Vorwalter Ph.D. Max-Planck-Institut Fur Kernphysik

Galileo D. Zacarias M.S. Universidad Autonoma de San Luis Potosi

E781 Publications

Observation of the Cabibbo suppressed decay X_c⁺ → pK ‾p ⁺. , S.Y. Jun, et al., Phys. Rev. Lett. 84,1857 (2000).

Total cross-section measurements with p ‾, S ‾ and protons on nuclei and nucleons around 600GeV/c. U. Dersch , et al.,. Accepted for Publication in Nucl. Phys. B, 2000.

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5.11 E789 - beauty-Quark Mesons and Baryons

Abilene Christian, Academia Sinica (Taiwan), Chicago,

Fermilab, LANL, LBL, Northern Illinois, South Carolina

E789 was designed to study two-body, two-prong decays of neutral hadrons that contain a charm quark or a bottom quark. E789 was an exploratory effort that failed to achieve sufficient sensitivity to see two-prong B-quark decays due to their very small decay fraction. Nevertheless, E789 did measure J/y decays from B mesons, two-body charm decay modes, and also provided new information on the cross sections and nuclear effects of D^o production in 800 GeV/c proton-nucleus collisions. These results were compared to QCD predictions.

E789 also measured the yield of J/y mesons from nuclear targets. The J/y yield per target nucleon is observed to decrease for heavy nuclei. This effect, similar to what is predicted for J/y production in very high-energy nucleus-nucleus quark-gluon plasma formation interactions, is not yet understood.

E789 Degree Recipients

M. Apolinski M.S. Northern Illinois University

Y.C. Chen Ph.D. National Cheng-Kun University

Matthew Scott Kowitt Ph.D. University of California at Berkeley

C. Lee M.S. Northern Illinois University

V. Martin M.S. Northern Illinois University

J. Sa M.S. Northern Illinois University

E789 Publications

Production of J/y at large x_F in 800 GeV/c p copper and p beryllium collisions., M.S. Kowitt, et al.,, Phys. Rev. Lett. 72, 1318 (1994).

Nuclear dependence of neutral D meson production by 800 GeV/c protons., M.J. Leitch, et al., Phys. Rev. Lett. 72, 2542 (1994).

Search for the decay D^o → m⁺ m^-., S. Mishra, et. al.,, Phys. Rev. D50, R9 (1994).

Measurement of J/y and y' production in 800 GeV/c proton gold collisions., M.H. Schub, et. al.,, Phys. Rev. D52, 1307 (1995).

Measurement of the bottom quark production cross-section in 800 GeV/c proton-gold collisions., D.M. Jansen, et al.,, Phys. Rev. Lett. 74, 3118 (1995).

Nuclear dependence of J/y by 800 GeV/c protons near x_F = 0_,., M.J. Leitch, et. al.,, Phys. Rev. D52, 4251 (1995).

Nuclear Dependence of single hadron and dihedron production in p A interactions at /s = 8.3 GeV. C.N. Brown, et. al.,, Phys. Rev. C54, 3195 (1996).

Search for flavor changing neutral currents and lepton family number violation in two body D^o decays., D. Pripstein, et al., Phys.Rev. D61, 032005 (2000).

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5.12 E791 - Hadroproduction of Charm

E-791: UC/Santa Cruz, CBPF (Brazil), Cincinnati, CINVESTAV (Mexico),

Fermilab, IIT, Kansas State, Mississippi, Ohio State, Princeton,

Puebla (Mexico), Rio de Janeiro (Brazil), Stanford, South Carolina,

Tel Aviv (Israel), Tufts, Wisconsin, Yale

The primary goal of the E791 experiment was to obtain detailed information on as large a number as possible of interactions in which charm quarks were produced. The information was to be used to study a range of physics issues from the way quarks turn into every-day particles to searches for phenomena not explained by known entities and interactions, "physics beyond the standard model" as it is called. These studies involved both the production characteristics and decay properties of charm particles.

E791 has published 8 papers on charm production and 16 on charm decays. Notably, these include the best current limits on several physics processes beyond the standard model: Flavor Changing Neutral Currents and other rare and forbidden decays, charm particle-antiparticle mixing, and CP violation in charm decays. Measurements of parameters of the standard model were also made, including particle lifetimes, several charm decay branching ratios, and form factors. From the details of the charm particle decays to multiple particles, E791 has contributed to the understanding of the dynamics of charm particle decay as well as measuring the parameters of several poorly-known particles which appear in charm decay. Another first was the search for a five-quark state, the pentaquark, which is expected in the standard model but has never been observed. E791 publications include papers on the total and differential production rates for charm particles and on particle-antiparticle production asymmetries.

E791 was the last in the series of experiments at the Fermilab Tagged Photon Laboratory (TPL). The final three in the series of four experiments took advantage of the Tevatron accelerator. In addition, E791 extended the philosophy of the earlier experiments in using "triggers" minimally - essentially recording almost every hadronic interaction event to magnetic tape. However, E791 used the expanded capabilities of parallelism in data collection, recording, and analysis computing made possible by more recent technologies. These technologies included 8 mm video tape used to record digital data, greatly expanded numbers of commercial computers to collect and organize data in real time, expanded banks of memory made possible by much less expensive storage, and "farms" of off-line computing engines working in parallel on processing data. In addition, E791 used a target for the incident beam which provided space for the produced charm particles to decay in air between target foils. Having the decays observed outside of material led to clear signals, unencumbered by backgrounds due to interactions in the target material. These approaches succeeded spectacularly, in that E791 recorded 50 terabytes of data containing the information on 20 billion interactions (a world record at the time) and successfully reconstructed about 250,000 charm events from this sample.

E791 Degree Recipients

Sharon May-tal Beck Ph.D. Tel Aviv University

Hendly Silva Carvalho Ph.D. Federal University of Rio de Janeiro

Eleazar Cuautle M.S. Universidad de Puebla

Shiral Devmal Ph.D. University of Cincinnati

George Fox Ph.D. University of South Carolina

Carla Gobel M.S. Pontificia Universidade Catolica Rio de Janeiro

Carla Gobel Ph.D. Centro Brasileiro de Pesquisas Fisicas

Andre Gouvea M.S. Centro Brasileiro de Pesquisas Fisicas

Gilad Hurvits Ph.D. Tel Aviv University

Penny Kasper Ph.D. Illinois Institute of Technology

Judy Leslie Ph.D. University of California at Santa Cruz

Aleardo Manacero Ph.D. State University of Campinas

Andre Massafferri M.S. Centro Brasileiro de Pesquisas Fisicas

Pablo Medina M.S. Cinvestav

Daniel Mihalcea Ph.D. Kansas State University

KC Peng Ph.D. Illinois Institute of Technology

Lalith Perera Ph.D. University of Cincinnati

Scott Radeztsky Ph.D. University of Wisconsin

Attanagoda Santha Ph.D. University of Cincinnati

Javier Solano Ph.D. Centro Brasileiro de Pesquisas Fisicas

Kevin Stenson Ph.D. University of Wisconsin

Arun Tripathi Ph.D. Ohio State University

Jim Wiener Ph.D. Princeton University

Nick Witchey Ph.D. Ohio State University

Shih-Wen Yang Ph.D. Kansas State University

Renata Zaliznyak Ph.D. Stanford University

E791 Publications

Multidimensional resonance analysis of L_c → p K p., E.M. Aitala, et al., Phys. Lett. B471, 449 (2000).

Lifetimes and lifetime difference between D⁰ → KK and D⁰ → K p., E.M. Aitala, et al., Phys. Rev. Lett. 83, 32 (1999).

Search for Rare and Forbidden Dilepton Decays of the D⁺, D_s⁺, and D⁰ Charmed Mesons., E.M. Aitala, et al., Phys. Lett. B462, 401 (1999).

Total Forward and Differential cross sections of Neutral D mesons produced in 500-GeV/c p^- nucleon interactions., E.M. Aitala, et al., Phys. Lett. B462, 225 (1999).

Measurement of the form-factor ratios for D_s⁺ → f l⁺ n_l., E.M. Aitala, et al., Phys. Lett. B450, 294 (1999).

Search for the Pentaquark via the P⁰ (anti-c s) → K*⁰ K^- p decay., E.M. Aitala, et al., Phys. Lett. B448, 303 (1999).

Measurement of the D_s⁺ lifetime., E.M. Aitala, et al., Phys. Lett. B445, 449 (1999).

Correlations between D and anti-D mesons produced in 500-GeV/c p-nucleon interactions'',

E.M. Aitala et al.,, Eur. J. of Phys. C4,1 (1999).

Measurement of the form-factor ratios for D⁺ → anti-K*⁰ l⁺ n_l.,., E.M. Aitala, et al., Phys. Lett. B440, 435 (1998).

Search for the Pentaquark via the P(anti-c s) ⁰ Decay to f p p., E.M. Aitala, et al., Phys. Rev. Lett. 81, 44 (1998).

Measurement of the Form-Factor Ratios for D⁺→ anti-K*^o e⁺ n_e E.M. Aitala, et al., Phys. Rev. Lett. 80, 1393 (1998).

Study of the Decay D⁰ → K^- K⁺ p^- p⁺., E.M. Aitala, et al., Phys. Lett. B423, 185 (1998).

Branching Fractions for D⁰ → K⁺ K^- and D⁰ → p⁺ p^-, and a Search for CP Violation in D⁰ Decays., E.M. Aitala, et al., Phys. Lett. B421, 405 (1998).

A Search for D^o anti-D^o Mixing and Doubly Cabibbo Suppressed Decays of the D⁰ in Hadronic Final States., E.M. Aitala, et al., Phys. Rev. D57, 13 (1998).

Asymmetries between the Production of D_s^- and D_s⁺ Mesons from 500-GeV/c p^- Nucleon Interactions as Functions of x_F and p_t², E.M. Aitala, et al., Phys. Lett. B411, 230 (1997).

Doubly Cabibbo Suppressed Decay D⁺ → K⁺ p⁺ p^-, E.M. Aitala, et al., Phys. Lett. B404, 187 (1997).

Search for CP Violation in Charged D Meson Decays., E.M. Aitala, et al., Phys. Lett. B403, 377 (1997).

Measurement of the Branching Ratio B(D⁺ → r l⁺ n_l.) / B(D⁺ → K*⁰ l⁺ n_l.)., E.M. Aitala, et al., Phys. Lett. B397, 325 (1997).

Observation of D-p Production Correlations in 500-GeV p-N Interactions., E.M. Aitala, et al., Phys. Lett. B403, 185 (1997).

Search for D-antiD mixing in Semileptonic Decay Mode., E.M. Aitala, et al., Phys. Rev. Lett. 77, 2384 (1996).

Mass Splitting and Production of S_c⁰ and S _c⁺⁺ measured in 500 GeV pN Interactions., E.M. Aitala, et al., Phys. Lett. B379, 292 (1996).

Asymmetries between the production of D⁺ and D^- mesons from 500-GeV/c p-nucleon interactions as a function of x_F and p_T²., E.M. Aitala, et al., Phys. Lett. B371, 157 (1996).

Search for the Flavor Changing Neutral Current Decays D⁺ → p⁺ m⁺ m ^- and D⁺ → p⁺ e⁺ e ^-.,

E.M. Aitala, et al., Phys. Rev. Lett. 76, 364 (1996).

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5.13 E831/FOCUS - Heavy Quarks study Using the Wideband Photon Beam

UC/Davis, CBPF (Brazil), CINVESTAV (Mexico), Colorado,

Fermilab, INFN/Frascati (Italy), Illinois/Champaign, Korea (Korea),

INFN/Milano (Italy), Milano (Italy), North Carolina, INFN/Pavia (Italy),

Pavia (Italy), Puebla (Mexico), Puerto Rico/Mayaguez, South Carolina,

Tennessee, Vanderbilt, Wisconsin, Yeonsei (Korea)

FOCUS is a high intensity photoproduction experiment that is designed to study the production and decay of charmed particles. The experiment enjoyed a successful data-taking period during 1996 and 1997 and reconstructed more than 1 million charm particles in D^o, D⁺→ Kp, Kpp, and Kppp.

Several improvements were made in the spectrometer upgraded from E687. A scintillating fiber calorimeter was fabricated and implemented in the first level trigger to improve efficiency. Both the first and second level triggers were speeded up in order to increase the livetime and silicon strip detectors were interleaved with the BeO segmented target. New detectors both reduced the electron and muon misidentification as well as improved the electron and muon efficiency.

The physics of the experiment involves high precision studies of D semileptonic decays with an emphasis on the determination of form factors and CKM matrix elements |V_cd| and |V_cs|, QCD studies of double-D events, a measurement of the absolute branching fraction for the D^o meson, searches for D^o mixing using hadronic and semileptonic final states, searches for CP violation, rare and forbidden decays, fully leptonic decays of the D⁺, and a systematic investigation of charm baryons and their lifetimes.

E831 Degree Recipients

Arturo Calandrino Laurea University of Milano

Edgar Casimiro Ph.D. Cinvestav

Paolo Dini Ph.D. University of Milano

Byeong Rok Ko M.S. Korea University

Jung Won Kwak M.S. Korea University

Luis Mendez M.S. University of Puerto Rico

Marco Merlo Ph.D. University of Pavia

Massimo Mezzadri Laurea University of Milano

Luigi Milazzo Laurea University of Milano

Alejandro Mirles M.S. University of Puerto Rico

Enrique Montiel M.S. University of Puerto Rico

David Olaya M.S. University of Puerto Rico

Juan Eduardo Ramirez M.S. University of Puerto Rico

Carlos Rivera M.S. University of Puerto Rico

Marco Rovere Laurea University of Milano

E.W. Vaandering Ph.D. University of Colorado

E831 Publications

A Measurement of lifetime differences in the neutral D meson system., submitted to Phys. Lett., [hep-ex/0004034] (Apr 2000) .