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The production of {pi}{sup {+-}}, K{sup {+-}}, p, k{sup 0} and {Lambda}{sup 0} in hadronic Z{sup 0} decays

Description: The authors have measured production fractions and spectra for {pi}{sup {+-}}, K{sup {+-}} and p, and production spectra for K{sup 0} and {Lambda}{sup 0} in both hadronic Z{sup 0} decays and a Z{sup 0} {yields} light quark (uds) subset at SLD. The SLD Cherenkov Ring Imaging Detector was used to identify charged hadrons. The CCD vertex detector was used to select the enriched uds sample. For the global sample, the results are consistent with previous experiments. The authors observe a clear flavor dependence in production spectra, but only a small effect in hadron fractions and {xi} = ln(1/x{sub p}) peak positions.
Date: August 1, 1995
Creator: Baird, K.
Partner: UNT Libraries Government Documents Department

Strange particle nuclear physics: Workshop summary

Description: Several sessions of the Working Group on Hadronic and Nuclear Spectroscopy dealt with different aspects of strange particle nuclear physics, including hypernuclear spectroscopy, strange dibaryons, and K{sup +} interactions with nuclei. Recent developments in this area are summarized here, and open questions are identified. Some prospects for optimum use of existing facilities, as well as the desired characteristics of future ones, are discussed.
Date: March 1, 1993
Creator: Dover, C. B.
Partner: UNT Libraries Government Documents Department

Recent results and directions in hypernuclear and Kaon physics

Description: This paper presents recent data and future plans for experiments at Brookhaven National Laboratory on hypernuclei and related topics. It will discuss experiment which put a single strange quark in the nucleus and an experiment to produce nuclei containing two strange quarks ({Lambda}{Lambda} hypernuclei).
Date: December 1, 1993
Creator: May, M.
Partner: UNT Libraries Government Documents Department

Hyperon polarization, crystal channeling, and E781 at Fermilab

Description: Early experiments at Fermilab observed significant polarization of inclusively produced hyperons. these and subsequent experiments showed that {Lambda}{degree} were produced polarized while {bar {Lambda}}{degree} had no polarization in the same kinematical region. Other hyperons and antihyperons were also seen to be polarized. Recent Fermilab experiments have showed this to be a rich and complex phenomena. Theoretical understanding is still lacking. Fermilab E761 has shown that bent single crystals can be used to process the polarization of hyperons and from the precession angle measure the hyperon`s magnetic moment. This opens the possibility of measuring the magnetic moments of charmed baryons. Finally, I will briefly discuss Fermilab E781, an experiment designed to study charmed particle production by {Sigma} {sup {minus}} hyperons.
Date: January 1, 1994
Creator: Lach, J.
Partner: UNT Libraries Government Documents Department

The study of hadronic matter at the highest energy density: The search for the deconfined quark-gluon phase using 2 TeV p-p Collisions. Progress report, January 1, 1989--December 31, 1989

Description: This report discusses: running E-735, 1988--1989; publications from the 1987--1988 of E-735; exclusive nuclear fragmentation experiment at the Bevelac using the new TPC; research and development on parallel plate avalanche detectors; and data analysis.
Date: December 1, 1989
Creator: Scharenbert, R. & Hirsch, A.
Partner: UNT Libraries Government Documents Department

A quark model of {bar {Lambda}}{Lambda} production in {bar p}p interactions

Description: A quark model which includes both scalar and vector contributions to the reaction mechanism (SV quark model) is used in a DWBA calculation of {anti {Lambda}}{Lambda} production in {bar p}p interactions. Total and differential cross-sections, polarizations, depolarizations, and spin-correlation coefficients are computed for laboratory momenta from threshold to 1695 MeV/c. The free parameters of the calculation are the scalar and vector strengths, a quark cluster size parameter, and the parameters of the unknown {anti {Lambda}}{Lambda} potentials. Good agreement with experiment is found for constructive interference of the scalar and vector terms, and for {anti {Lambda}}{Lambda} potentials which differ from those suggested by several authors on the basis of SU(3) arguments. The fit to the data is better than that obtained by other quark models, which use only scalar or vector annihilation terms. The agreement with experiment is also better than that found in meson-exchange models. The recent suggestion [1] that measurement of the depolarization parameter D{sub nn} can be used to discriminate between meson-exchange and quark models is examined in detail. We conclude that a measurement of D{sub nn} will provide a test of which of these models, as presently constructed, is the more appropriate description of strangeness production in the {bar p}p {yields} {anti {Lambda}}{Lambda} reaction.
Date: December 31, 1993
Creator: Alberg, M. A.; Henley, E. M.; Wilets, L. & Kunz, P. D.
Partner: UNT Libraries Government Documents Department

A single particle energies

Description: We consider the binding energies of {Lambda} hypernuclei (HN), in particular the single-particle (s.p.) energy data, which have been obtained for a wide range of HN with mass numbers A {le} 89 and for orbital angular momenta {ell}{sub {Lambda}} {le} 4. We briefly review some of the relevant properties of A hypernuclei. These are nuclei {sub {Lambda}}{sup A}Z with baryon number A in which a single {Lambda} hyperon (baryon number = 1) is bound to an ordinary nucleus {sup A}Z consisting of A - 1 nucleons = Z protons + N neutrons. The {Lambda} hyperon is neutral, has spin 1/2, strangeness S = {minus}1, isospin I = O and a mass M{sub {Lambda}} = 1116 MeV/c{sup 2}. Although the {Lambda} interacts with a nucleon, its interaction is only about half as strong as that between two nucleons, and thus very roughly V{sub {Lambda}N} {approx} 0.5 V{sub NN}. As a result, the two-body {Lambda}N system is unbound, and the lightest bound HN is the three-body hypertriton {sub {Lambda}}{sup 3}H in which the {Lambda} is bound to a deuteron with the {Lambda}-d separation energy being only {approx} 0.1 MeV corresponding to an exponential tail of radius {approx} 15 fm! In strong interactions the strangeness S is of course conserved, and the {Lambda} is distinct from the nucleons. In a HN strangeness changes only in the weak decays of the {Lambda} which can decay either via ``free`` pionic decay {Lambda} {yields} N + {pi} or via induced decay {Lambda} + N {yields} N + N which is only possible in the presence of nucleons. Because of the small energy release the pionic decay is strongly suppressed in all but the lightest HN and the induced decay dominates. However, the weak decay lifetime {approx} 10{sup {minus}10}s is in fact close to the lifetime of ...
Date: September 1, 1993
Creator: Bodmer, A. R.; Usmani, Q. N. & Sami, M.
Partner: UNT Libraries Government Documents Department

Preliminary measurements of production of {pi}{sup {plus_minus}}, K{sup {plus_minus}}, p, K{sup 0} and {Lambda}{sup 0} in hadronic Z{sup 0} decays

Description: We have measured production of {pi}{sup {+-}}, {Kappa}{sup {+-}}, {ital p}/{ital {bar p}}, {Kappa}{sup 0} and {Lambda}{sup 0}/{bar {Lambda}}{sup 0} as a function of momentum in inclusive hadronic {ital Z}{sup 0} decay events and separately in events containing primary light-({ital uds}) and {ital b}-quarks. The SLD Cherenkov Ring Imaging Detector was used to identify charged pions, kaons, and protons over most of the available momentum range 0.8{lt}{ital p}{lt}33 GeV/c. The neutral {Kappa}{sup 0}{sub s} and {Lambda}{sup 0} were reconstructed using the {pi}{sup +}{pi}{sup -} and {ital p}{pi}{sup -} decay modes, respectively. We present the first comparisons of momentum of charged tracks measured in the SLD Vertex Detector. Substantial differences are observed, consistent with the kinematics of {ital B}-hadron production in Z{sup 0} decays and the properties of {ital B}-hadron decays as measured at lower energies.
Date: June 1, 1996
Creator: Collaboration, The SLD
Partner: UNT Libraries Government Documents Department

Statistical properties of the multiparticle final state as a function of the average event in p{sub t} in soft {anti p}p interactions at {radical}s = 1800 and 630 GeV

Description: A preliminary analysis of average properties of softly produced events in {ital p{anti p}} interactions at the Tevatron energies is presented. Data have been collected by the Collider Detector at Fermilab using a minimum bias trigger. The average charged event multiplicity, the production of strange particles and the strength of the short range pseudorapidity correlation have been studied as a function of the average transverse momentum of the event. Comparisons have been made between the two center of mass energies 1800 and 630 GeV and also with a sample of selected jet events. Peculiar characteristics in the behavior of these variables are highlighted.
Date: November 1, 1996
Creator: Fiorni, I.
Partner: UNT Libraries Government Documents Department

Production of {pi}{sup {plus_minus}}, K{sup {plus_minus}}, p, K{sup 0} and {Lambda}{sup 0} in hadronic Z{sup 0} decays

Description: We have measured production rates and spectra of {pi}{sup plus minus}, K{sup plus minus}, p/{bar p}, K{sup O} and {Lambda}{sup O}/{bar {Lambda}}{sup O} in light- and heavy-flavor hadronic Z{sup O} decays and for particles and antiparticles separately in quark jets. The SLD Cherenkov ring imaging detector was used to identify charged hadrons. Samples enriched in light (uds) and b events were tagged using impact parameters of charged tracks, and a sample enriched in quark (over antiquark) jets was tagged using the electron beam polarization, We observe a clear flavor dependence in production rates and spectrum shapes, but only a small effect in {xi}=ln(1/x{sub p}) peak positions. Differences between baryons and antibaryon spectra in quark jets offer direct confirmation that faster particles are more likely to contain the initial quark.
Date: July 1, 1995
Partner: UNT Libraries Government Documents Department

Production of {pi}{sup {+-}}, K{sup {+-}}, K{sup 0}, K*{sup 0}, {phi}, p and {Lambda}{sup 0} in hadronic Z{sup 0} decays

Description: The authors have measured production rates as a function of momentum of the identified hadrons {pi}{sup +}, K{sup +}, K{sup 0}, K*{sup 0}, {phi}, p, {Lambda}{sup 0} and their antihadrons in inclusive hadronic Z{sup 0} decays, as well as separately in decays into light, c and b flavors. In addition they have compared hadron and antihadron production rates in light quark (rather than antiquark) jets. The SLD Cherenkov Ring Imaging Detector was used to identify charged hadrons. The vertex detector was used to tag high-purity samples of light- and b-flavor events. The electron beam polarization was used to tag samples of quark and antiquark jets. Clear flavor dependences are observed, consistent with expectations based upon measured production and decay properties of heavy hadrons. They use the light-flavor results to test the predictions of MLLA QCD and of various fragmentation models. Differences between hadron and antihadron production in light quark jets are observed at high momentum fraction, providing direct evidence that higher-momentum particles are more likely to contain a primary quark or antiquark, and they use these results to make a new direct measurement of strangeness suppression in the jet fragmentation process.
Date: June 1, 1997
Creator: Abe, K.; Abe, K.; Akagi, T. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

HyperCP at Fermilab -- A status report

Description: The primary purpose of the HyperCP experiment at Fermilab is to test CP in hyperon decays by comparing the alpha parameters for {Xi}{sup -} and {Xi}{sup +} decays in the decay sequence: {Xi}{sup -} {yields} {pi} + {Lambda}{sup 0}, {Lambda}{sup 0} {yields} {pi}{sup -} + p. In addition, we can test CP in charged kaon decays by comparing the slopes of the Dalitz plot for K{sup +} and K{sup -} decays. They are also looking at rare decay modes of charged kaons and hyperons, particularly those involving muons.
Date: October 23, 2001
Creator: al., M. J. Longo et
Partner: UNT Libraries Government Documents Department

Weak decay of LAMBDA hypernuclei

Description: Binding a lambda to a nucleus presents an opportunity to study the four fermion weak interaction. In particular a ..lambda.. bound in the 1s orbit of the nuclear potential can only decay through a strangeness nonconserving weak current. Since the relevant coupling constants are known fairly well and the decay rate can be calculated, it is important to provide the most complete set of experimental data to check the calculations. Because of the competition between mesonic and nonmesonic decay modes of ..lambda.. hypernuclei the experimental situation is somewhat complicated. What is needed is data in (a) very light nuclei where the mesonic mode dominates and (b) somewhat heavier nuclei where the mesonic mode is suppressed so that the nonmesonic mode dominates. The bulk of the existing data is related to hydrogen and helium, which are examples of case (a). We describe an experiment now under construction, which has been designed to provide comparable or better data for the case of /sup 12//sub LAMBDA/C where the nonmesonic decay mode is expected to dominate (case b). We present the detailed motivation of the measurement, together with discussions of recent calculations and relevant data. We also describe the planned experiment and the advantages of LAMPF II for these investigations.
Date: unknown
Creator: Barnes, P. D. & Grace, R.
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

Physics of few-body lambda hypernuclei

Description: The energies of the particle-stable states in few-body ..lambda.. hypernuclei are summarized. Other topics reviewed include: the role of the hypertriton in determining the spin dependence of the ..lambda..N force, the role of the hypertriton in three-body force investigations, the effect of medium modifications upon ..lambda..N-..sigma..N coupling in the ..lambda..-4 isodoublet and the spin dependence of the ..lambda..N force, the importance of exact equation formalisms in interpreting precision data, and the need for a renewed effort to identify and measure the masses of ..lambda lambda.. hyperfragments. 40 refs., 4 figs., 3 tabs.
Date: January 1, 1987
Creator: Gibson, B.F.
Partner: UNT Libraries Government Documents Department