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Heavy quark symmetries and the decays baryon antibaryon

Description: We enumerate the form factors necessary to describe the two-body baryonic decays of B mesons.We use the symmetries of the heavy quark effective theory to arrive at some relations among these form factors, when at least one of the daughter baryons is heavy.
Date: October 1, 1991
Creator: Roberts, Winston; Roberts, Winston & Ryzak, Z.
Partner: UNT Libraries Government Documents Department

Antibaryon production in AU+AU collisions at the AGS.

Description: Experiment E917 at the Brookhaven AGS has made a measurement of near-mid-rapidity antibaryon production in both the antiproton and antilambda channel. Results on dN/dy and inverse slope parameters are shown. A preliminary measurement of the ratio {bar {Lambda}}/{bar p} is also presented.
Date: July 2, 1999
Creator: Back, B. B.; Betts, R. R.; Chang, J.; Chang, W. C.; Chi, C. Y.; Collaboration, E917 et al.
Partner: UNT Libraries Government Documents Department

Results from experiment E917 for Au + Au collisions at the AGS.

Description: The effects of baryon stopping and its resulting energy deposition on the dynamics of Au + Au collisions at 6, 8 and 10.8 GeV/nucleon are explored with recent results from the AGS experiment E917. Current analyses of stopping, collective flow signals and HBT parameters are presented. Strangeness and anti-baryon production is examined using the yields of anti-lambdas and anti-protons.
Date: August 4, 1999
Creator: Back, B. B.; Betts, R. R.; Chang, J.; Chang, W. C.; Collaboration, E917; Gillitzer, A. et al.
Partner: UNT Libraries Government Documents Department

Vacuum, matter, antimatter and the problem of cold compression

Description: We discuss the possibility of producing a new kind of nuclear system by putting a few antibaryons inside ordinary nuclei. The structure of such systems is calculated within the relativistic mean-field model assuming that the nucleon and antinucleon potentials are related by the G-parity transformation. The presence of antinucleons leads to decreasing vector potential and increasing scalar potential for the nucleons. As a result, a strongly bound system of high density is formed. Due to the significant reduction of the available phase space the annihilation probability might be strongly suppressed in such systems.
Date: January 1, 2003
Creator: Greiner, Walter, & Buervenich, T. J. (Thomas J.)
Partner: UNT Libraries Government Documents Department

Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR

Description: Identified charged particle spectra of {pi}{sup {+-}}, K{sup {+-}}, p and {bar p} at mid-rapidity (|y| < 0.1) measured by the dE/dx method in the STAR-TPC are reported for pp and d + Au collisions at {radical}s{sub NN} = 200 GeV and for Au + Au collisions at 62.4 GeV, 130 GeV, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm{sub 3} for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au + Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au + Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters due to the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of collision system or centrality; its value is ...
Date: April 11, 2009
Creator: Coll, STAR
Partner: UNT Libraries Government Documents Department

Measurement of Branching Fractions and CP-ViolatingCharge Asymmetries for B Meson Decays to D(*)D(*), and Implications for the CKMAngle gamma

Description: In summary, the authors have measured branching fractions, upper limits, and charge asymmetries for all B meson decays to D{sup (*)} {bar D}{sup (*)}.
Date: July 6, 2006
Creator: Aubert, B.; Barate, R.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y. et al.
Partner: UNT Libraries Government Documents Department

Study of B-Meson Decays to Final States with a Single Charm Baryon

Description: A study of B-meson decays to final states with a single charm baryon is presented based on data recorded by the BABAR detector at the Stanford Linear Accelerator Center. Although the B meson is the lightest bottom-flavored meson, it is heavy enough to decay to a baryon made of three quarks and an antibaryon made of three antiquarks. By studying the baryonic weak decays of the B meson, we can investigate baryon production mechanisms in heavy meson decays. In particular, we measure the rates of the decays B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -} and {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}. Comparing these rates, we confirm an observed trend in baryonic B decays that the decay with the lower energy release, B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -}, is favored over {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}. The dynamics of the baryon-antibaryon ({Lambda}{sub c}{sup +}{bar p}) system in the three-body decay also provide insight into baryon-antibaryon production mechanisms. The B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -} system is a laboratory for searches for excited {Sigma}{sub c} baryon states; we observe the resonant decays B{sup -} {yields} {Sigma}{sub c}(2455){sup 0}{bar p} and B{sup -} {yields} {Sigma}{sub c}(2800){sup 0}{bar p}. This is the first observation of the decay B{sup -} {yields} {Sigma}{sub c}(2800){sup 0}{bar p}; however, the mass of the observed {Sigma}{sub c}(2800){sup 0} state is inconsistent with previous measurements. Finally, we examine the angular distribution of the B{sup -} {yields} {Sigma}{sub c}(2455){sup 0}{bar p} decays and measure the spin of the {Sigma}{sub c}(2455){sup 0} baryon to be J = 1/2, as predicted by the quark model.
Date: June 2, 2009
Creator: Majewski, Stephanie A.
Partner: UNT Libraries Government Documents Department

Can antibaryons signal the formation of a quark-gluon plasma

Description: We report on recent work which indicates that an enhancement of antibaryons produced in the hadronization phase transition can signal the existence of a transient quark-gluon plasma phase formed in a heavy-ion collision. The basis of the enhancement mechanism is the realization that antiquark densities are typically a factor 3 higher in the quark-gluon plasma phase than in hadronic matter at the same temperature and baryon density. The signal is improved by studying larger clusters of antimatter, i.e., light antinuclei like anti ..cap alpha.., in the central rapidity region. The effects of the transition dynamics and of the first order nature of the phase transition on the hadronization process are discussed.
Date: January 1, 1985
Creator: Heinz, U.; Subramanian, P.R. & Greiner, W.
Partner: UNT Libraries Government Documents Department

The AGS complex as an antiproton filling station

Description: A transportable antiproton storage device to store and transport low energy antiprotons for use away from the production facility has been proposed previously. In this note the AGS complex is examined as a possible filling station for such a device. The production and collection rate of antiprotons is discussed, and a possible scenario is offered for the antiproton collection and deceleration cycle. (LEW)
Date: January 1, 1987
Creator: Lee, Y.Y. & Lowenstein, D.I.
Partner: UNT Libraries Government Documents Department

Search for. lambda. anti. lambda. heavy states at ISA

Description: The possibility of observing ..lambda..anti..lambda.. heavy states using the Isabelle storage rings is discussed. Not many particles are known to date to decay into ..lambda..anti..lambda... The J/psi is a notable exception, with a branching ratio of about 0.2% (vs. 7% into e/sup +/e/sup -/ and ..mu../sup +/..mu../sup -/). However, it is not inconceivable that higher mass states, produced at Isabelle energies, will have substantial branching fractions into ..lambda..anti..lambda... If this will indeed be the case, then one may think of getting additional information on the properties of the new states by taking advantage of the parity-violating ..lambda.. and anti..lambda.. decays. Detectors, rate and background considerations, and methods of particle detection are discussed.
Date: January 1, 1977
Creator: Flaminio, V.; Lesnik, A. & Rehak, P.
Partner: UNT Libraries Government Documents Department

Looking for new gravitational forces with antiprotons

Description: Quite general arguments based on the principle of equivalence and modern field theory show that it is possible for the gravitational acceleration of antimatter to be different than that for matter. Further, there is no experimental evidence to rule out the possibility. In fact, some evidence indicates there may be unexpected effects. Thus, the planned experiment to measure the gravitational acceleration of antiprotons is of fundamental importance. 20 refs., 3 figs.
Date: January 1, 1987
Creator: Nieto, M.M. & Bonner, B.E.
Partner: UNT Libraries Government Documents Department

Phase transitions in nuclear matter

Description: The rather general circumstances under which a phase transition in hadronic matter at finite temperature to an abnormal phase in which baryon effective masses become small and in which copious baryon-antibaryon pairs appear is emphasized. A preview is also given of a soliton model of dense matter, in which at a density of about seven times nuclear density, matter ceases to be a color insulator and becomes increasingly color conducting. 22 references.
Date: November 1, 1984
Creator: Glendenning, N.K.
Partner: UNT Libraries Government Documents Department

Threshold effects and oscillations in models with t-channel factorization

Description: From meeting of the division of particles and fields; Berkeley, California USA (13 Aug 1973). Threshold effects and oscillating cross sections are reviewed in the context of models (such as the multiperipheral) which employ factorization and indefinite repetition in the t-channel. The origin of logarithmic energy thresholds is illustrated by the ABFST model and applied to antibaryon production and rising cross sections at high energy. Then one discusses large-mass diffraction dissociation and it is argued that this process is not responsible for the increase in the p-p total cross section at ISR energies. (auth)
Date: September 26, 1973
Creator: Koplik, J.
Partner: UNT Libraries Government Documents Department

Experimental area plans for an advanced hadron facility

Description: A brief overview is presented of the current plans for an experimental area for a new advanced hadron facility for the exploration of nuclear and particle physics. The facility, LAMPF II, is presently visualized as consisting of the LAMPF linac sending 800 MeV protons to a 6 GeV booster ring followed by a 45 GeV main ring. Two experimental areas area planned. The first is intended to provide neutrinos via a pair of pulsed focusing horns. The other is designed to accommodate secondary beams that span the range of useful energies up to GeV/c. Beam specification goals are discussed with respect to source brightness, beam purity, and beam-line acceptance and length. The various beam lines are briefly described. Production cross sections and rates are estimated for antiproton production. Problems of thermal energy deposition in both components and targets and of effectiveness of particle separators are discussed. 9 refs. (LEW)
Date: January 1, 1986
Creator: Hoffman, E.W.; Macek, R.J. & Tschalear, C.
Partner: UNT Libraries Government Documents Department

Antiproton production for Tevatron

Description: Needs to improve the Fermilab Pbar Source for the Tevatron Upgrade and discrepancies in predictions of the antiproton yields have forced us to develop the production model based on the modern data and to incorporate this model to the current version of MARS10 code. The inclusive scheme of this code with the use of statistical weights allows the production of antiprotons to be enhanced within the phase space region of interest, which is extremely effective for optimization of Pbar Source parameters and for developing of such an idea as a beam sweeping system. Antiproton production model included in the modified version of our Monte Carlo program MARS10M for the inclusive simulation of hadronic cascades, as for other particles throughout the program, is based on a factorization approach for hadron-nucleus differential cross-section. To describe antiproton inclusive spectra in pp-collisions a phenomenological model has been used modified in the low-Pt region. The antiproton production in pion-nucleon interactions is described in the frame of our simple phenomenological model based on the modern data. In describing of the of antiproton production cross-sections ratio in hadron-nucleus and hadron-nucleon collisions the ideas of soft hadronization of color strings and all the present experimental data have been used. Some comparisons of our model with experimental data are presented in the wide intervals of initial momenta, antiproton kinematical variables and nuclei. In all the cases the agreement is pretty good what gives us an assurance in the consequent studies carried out for the Fermilab Pbar Source. The results of such study are presented in this paper.
Date: March 1, 1991
Creator: Azhgirey, I.L.; Mokhov, N.V. & Striganov, S.I. (Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Serpukhov (USSR). Inst. Fiziki Vysokikh Ehnergij)
Partner: UNT Libraries Government Documents Department

Accelerator Technology Program. Status report, April-September 1985

Description: This report presents highlights of major projects in the Accelerator Technology (AT) Division of the Los Alamos National Laboratory. Radio-frequency and microwave technology are dealt with. The p-bar gravity experiment, accelerator theory and simulation activities, the Proton Storage Ring, and the Fusion Materials Irradiation Test accelerator are discussed. Activities on the proposed LAMPF II accelerator, the BEAR (Beam Experiment Aboard Rocket) project, beam dynamics, the National Bureau of Standards racetrack microtron, and the University of Illinois racetrack microtron are covered. Papers published by AT-Division personnel during this reporting period are listed.
Date: September 1, 1986
Creator: Jameson, R.A. & Schriber, S.O. (comps.)
Partner: UNT Libraries Government Documents Department

Early work at the Bevatron: a personal account

Description: Personal reminiscences of the author's work at the Bevatron in the 1950's are given. Setting up photographic emulsions and startup of the Bevatron are recalled. A brief account is given of the physics prior to the Bevatron, followed by the development of the machine and its use to study K mesons, theta and tau particles. The search for the antiproton is remembered. 16 refs., 6 figs. (LEW)
Date: December 1, 1985
Creator: Goldhaber, G.
Partner: UNT Libraries Government Documents Department

Experiment to measure the gravitational force on the antiproton

Description: A collaboration has been formed to measure the acceleration of antiprotons in the earth's gravitational field. The technique is to produce, decelerate, and trap quantities of antiprotons, to cool them to untralow energy, and to measure their acceleration in a time-of-flight experiment. Present plans and the results of initial efforts toward this end are presented.
Date: January 1, 1985
Creator: Brown, R.E.
Partner: UNT Libraries Government Documents Department

Physics with ultra-low energy antiprotons

Description: The experimental observation that all forms of matter experience the same gravitational acceleration is embodied in the weak equivalence principle of gravitational physics. However no experiment has tested this principle for particles of antimatter such as the antiproton or the antihydrogen atom. Clearly the question of whether antimatter is in compliance with weak equivalence is a fundamental experimental issue, which can best be addressed at an ultra-low energy antiproton facility. This paper addresses the issue. 20 refs.
Date: January 1, 1989
Creator: Holtkamp, D.B.; Holzscheiter, M.H. & Hughes, R.J. (Los Alamos National Lab., NM (USA))
Partner: UNT Libraries Government Documents Department

Physics with low temperature antiprotons

Description: The advent of the new beam cooling techniques and their application to antiproton production has already made possible major advances in high energy physics. These same techniques offer uniquely exciting possibilities for ultralow energy physics. Through a combination of deceleration stages, antiprotons produced at several GeV (where the production cross section is at a maximum) can be made available for experiments at thermal velocities. High precision measurements of the antiproton mass and magnetic moment can be performed. Comparison of these measurements with those for the proton will test the CPT invariance of internal baryon dynamics at an unprecedented level. In addition the gravitational constant for antimatter can be measured for the first time, and to high accuracy. Each of these measurements will provide very important information on the dynamical symmetry between matter and antimatter in our universe. Antiprotons at thermal velocities will also make these fundamental particles available for experiments in condensed matter and atomic physics. The recent speculation that antiprotons may form metastable states in some forms of normal matter could open many new avenues of basic and applied research.
Date: January 1, 1985
Creator: Hynes, M.V.
Partner: UNT Libraries Government Documents Department

Baryon production at PEP

Description: Measurements of inclusive ..lambda.. + anti ..lambda.. production for 1.0 less than or equal to p less than or equal to 10.0 GeV/c and p + anti p production for 0.4 less than or equal to p less than or equal to 2.0 GeV/c show significant baryon production in e/sup +/e/sup -/ annihilation at E/sub cm/ = 29 GeV. ..lambda.. + anti ..lambda.. production represents 0.2 ..lambda..'s or anti ..lambda..'s per PEP event while the observed p + anti p production implies all baryon-antibaryon pair production is occurring at least as often as 0.6 per event, depending on the yet to be measured p + anti p production at high momentum. Comparisons are made with the first theoretical attempts to account for baryon production at these energies.
Date: September 1, 1981
Creator: Goldhaber, G. & Weiss, J.M.
Partner: UNT Libraries Government Documents Department

Wake-riding electrons emitted by antiprotons traversing solid targets

Description: The dielectric response of the medium to a swift ion induces collective charge-density fluctuations which result in an oscillatory polarization potential trailing the ion ( wake''). The concept of such a wake'' dates back to Bohr. Meanwhile, a large number of investigations implementing approximations at various levels of sophistication have been performed. The plasmon-pole approximation is one of the simplest approximation which still accounts qualitatively for most of the features of the wake. Clearly, more subtle effects like bow waves and other dispersion effects are neglected. We will restrict ourselves in this paper to the plasmon-pole approximation including a phenomenological damping. We will neglect the effects of the self-wake which can affect the shape of the wake potential. 21 refs., 8 figs.
Date: January 1, 1989
Creator: Burgdorfer, J.; Wang, J. & Mueller, J. (Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)
Partner: UNT Libraries Government Documents Department