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Description: Information on the properties of the nuclear interactions of hyperons, weak interactions of the hyperon ( LAMBDA ), and properties of nuclei that could be obtained by studying hypernuclei is discussed. Experiments that should be able to give relevant information in the near future are considered. (D.C.W.)
Date: January 1, 1963
Creator: Dalitz, R H
Partner: UNT Libraries Government Documents Department

Double hypernuclei or H particles?

Description: We will begin with the H particle, stranglets and strange matter since these proposed objects are a strong motivation for studying hypernuclei containing two strange quarks. The data on {Lambda}{Lambda} and {Xi} hypernuclei will then be reviewed, as well as experiments in progress or scheduled. Many have contributed to the work that will be discussed, which took place primarily at KEK and BNL. At this time of transition, and anticipation of new experimental results and facilities, we take time to remember Carl Dover and Hiro Bando who contributed so much to this field.
Date: December 31, 1996
Creator: May, M.
Partner: UNT Libraries Government Documents Department

A production in Au-Au collisions at the AGS

Description: The results of a measurement of production in Au-Au collisions at 11.6 A GeV/c by Experiment 891 at the Brookhaven AGS are presented. The measurements cover the rapidity region of 2.0 to 3.2 and transverse momenta of 0.0 to 1.4 GeV/c. The results are compared with similar measurements of Si-Si interactions and the predictions of ARC and RQMD models.
Date: December 31, 1996
Creator: Saulys, A.C.; Eiseman, S.E. & Foley, K.J.
Partner: UNT Libraries Government Documents Department

Do narrow {Sigma}-hypernuclear states exist?

Description: Reports of narrow states in {Sigma}-hypernucleus production have appeared from time to time. The present experiment is a repeat of the first and seemingly most definitive such experiment, that on a target of {sup 9}Be, but with much better statistics. No narrow states were observed.
Date: December 31, 1995
Creator: Chrien, R.E.
Partner: UNT Libraries Government Documents Department

Strange particle production and s-quark asymmetry

Description: Using hadronic Z{sup 0} decays recorded by the SLD experiment at SLAC, we have studied the production of strange particles as a function of momentum. A high-purity sample of K{sup {+-}} was tagged using Cherenkov Ring Imaging Detector (CRID). The {phi}, {Lambda} and K{sub s} were reconstructed in the K{sup +}K{sup -}, p-{pi} and {pi}{sup +}{pi}{sup -} modes respectively, and CRID identification of K{sup {+-}} and p was used to obtain pure samples of {phi} and {Lambda}. We have used the high electron-beam polarisation delivered by the SLC to measure the left-right forward-backward production asymmetries of these particles, and discuss the relationship of these quantities to the underlying strange quark asymmetry in Z{sup 0} decays.
Date: August 1, 1996
Creator: Narita, S.
Partner: UNT Libraries Government Documents Department

Hadron production in light and heavy, quark and antiquark jets

Description: The authors review four hadronization studies performed by the SLD experiment at SLAC, involving separation of light (Z{sup 0} {r_arrow} u{anti u}, d{anti d}, s{anti s}), c, and b flavors using precision vertexing, and separation of q- and {anti q}-jets using the highly polarized SLC electron beam. They measured the differences between the average charged multiplicities in Z{sup 0} {r_arrow} light, {r_arrow} c{anti c}, and {r_arrow}b{anti b} events, and found that the results were consistent with predictions of perturbative QCD. Next, they measured {pi}/{Kappa}/p/{Kappa}{sup 0}/{Lambda}{sup 0} production in light events for the first time, and compared with production in c- and b-flavor events. They then examined particle production differences in light quark and antiquark hemispheres, and observed more high momentum baryons and K{sup {minus}}`s than antibaryons and K{sup +}`s in quark hemispheres, consistent with the leading particle hypothesis. Lastly, they performed a search for jet handedness in light q- and {anti q}-jets. Assuming Standard Model values of quark polarization in Z{sup 0} decays, they have set an improved upper limit on the analyzing power of the handedness method.
Date: August 1, 1996
Creator: Baird, K.G. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

L Polarization in Unpolarized Hadron Reactions.

Description: The transverse polarization observed in the inclusive production of {Lambda} hyperons in the high energy collisions of unpolarized hadrons is tackled by considering a new set of spin and {kappa}{perpendicular} dependent quark fragmentation functions. Simple phenomenological expressions for these new ''polarizing fragmentation functions'' are obtained by a fit of the data on {Lambda}'s and {bar {Lambda}}'s produced in p - N processes.
Date: April 23, 2001
Creator: Anselmino, M.; Boer, D.; Dalesio, U. & Murgia, F.
Partner: UNT Libraries Government Documents Department

Transversely Polarized L Production.

Description: Transversely polarized {Lambda} production in hard scattering processes is discussed in terms of a leading twist T-odd fragmentation function which describes the fragmentation of an unpolarized quark into a transversely polarized {Lambda}. We focus on the properties of this function and its relevance for the RHIC and HERMES experiments.
Date: May 22, 2000
Creator: BORER, D.
Partner: UNT Libraries Government Documents Department

Associated {Lambda} production at Jefferson Lab

Description: The {sup 1}H(e, e{prime}K{sup +}){Lambda} and {sup 1}H(e, e{prime}K{sup +}){Sigma}{sup 0} reactions were studied as a function of the squared four-momentum-transfer, Q{sup 2}, and the virtual photon polarization, {var_epsilon}, thus enabling the separation of the longitudinal and transverse parts of the cross section. The existence of a sensibly large longitudinal component for the {sup 1}H(e, e{prime}K{sup +}){Lambda} reaction seems to be sustained by these data.
Date: December 31, 1997
Creator: Niculescu, G.; Baker, O.K.; Avery, S. & Collaboration, E93018
Partner: UNT Libraries Government Documents Department

The Lambda Lambda interaction and the reaction Xi plus deuteron goes to neutron plus Lambda plus Lambda{dagger}

Description: Interest in the {Lambda}{Lambda} interaction is partly due to the presence of quark-model predictions for an S = {minus}2 dibaryon, and partly to the interest in the role of the coupling between the {Lambda}{Lambda} and {Xi}{Nu} channels in {Lambda}{Lambda} hypernuclei. This latter effect is expected to be substantially more important than the coupling of the {Nu}{Nu} to the {Nu}{Delta} channel in the S = 0 sector, since the difference in threshold between the {Lambda}{Lambda} and {Xi}{Nu} is only {approx}25 MeV. In the absence of any direct measurement of the {Lambda}{Lambda} amplitude, one must resort to either {Lambda}{Lambda} hypernuclei, or to a reaction with a {Lambda}{Lambda} final-state interaction to determine the {Upsilon}{Upsilon} interaction. In this report the authors present results of a theoretical study of the hypernucleus {sub {Lambda}{Lambda}}{sup 6}He and the reaction {Xi}d {r_arrow} n{Lambda}{Lambda} whereby they examine the sensitivity of the calculations to details of the {Lambda}{Lambda} potential, and the coupling between the {Lambda}{Lambda} and the {Xi}{Nu} channels.
Date: July 1, 1997
Creator: Carr, S.B.; Afnan, I.R. & Gibson, B.F.
Partner: UNT Libraries Government Documents Department

Strange particle production in hadronic Z{sup 0} decays

Description: A study has been made of neutral strange baryons and pseudoscalar mesons produced in hadronic decays of the weak gauge boson V. The experiment was performed at the Stanford Linear Accelerator Center, which has the unique capability of colliding highly polarized electrons with unpolarized positrons. Overall production rates and spectra of the K{sup 0} and the {Lambda}{sup 0} (+{Lambda}{sup 0}) were measured and compared with other experiments as well as with Quantum Chromodynamics calculations. The combination of the small, stable beam spots produced by the SLAC Linear Collider (SLC) and the precision vertexing capabilities of the SLC Large Detector (SLD) permitted the separation of the hadronic events into three quark flavor-enriched samples. An unfolding was performed to obtain flavor-pure samples, and for the first time measurements were made of K{sup 0} and {Lambda}{sup 0} (+{Lambda}{sup 0}) production rates and spectra in uds, c, and b quark events at the Z{sup 0} pole. This measurement revealed significant production differences. Utilizing the large quark production asymmetry due to the polarized electron beam, high-purity quark and antiquark jet samples were obtained. The first measurement of production differences of the {Lambda}{sup 0} baryon in quark and antiquark jets was performed, which provided clear evidence for a leading particle effect at high momenta.
Date: April 1, 1996
Creator: Baird, K.G. III
Partner: UNT Libraries Government Documents Department

The Strong and Weak Interactions of Bound a-Particles

Description: Calculations on the S-wave LAMBDA -N and LAMBDA - LAMBDA interactions, binding energies for the p-shell hypernuclei, and the mesic decay and nonmesonic de-excitation of the A-particle are discussed. The theory behind the calculations, as well as the results and their interpretation, are considered. (D.C.W.)
Date: January 1, 1963
Creator: Dalitz, R. H.
Partner: UNT Libraries Government Documents Department

{Lambda} production in AuAu collisions at 11.6 GeV/c

Description: I present the first measurement at AGS energies of the rapidity and transverse mass distributions for A production with Au beam on Au target. The measurements cover the rapidity region of 2.0 to 3.2 and transverse momenta of 0.0 to 1.4 GeV/c. The results are compared with the predictions of two models.
Date: December 31, 1996
Creator: Foley, K.J. & Collaboration, E891
Partner: UNT Libraries Government Documents Department

Production of {pi}{sup {plus_minus}}, K{sup {plus_minus}}, p, K{sup 0}{sub s}, {Lambda}{sup 0}, K{sup *0} and {phi} in Hadronic Z{sup 0} Decays

Description: Production rates and momentum distributions have been measured for {pi}{sup {+-}}, K{sup {+-}}, p, K{sup 0}{sub s}, {Lambda}{sup 0}, K{sup *0} and {phi} in 150,000 hadronic Z{sup 0} decays recorded by the SLD detector at the SLD collider at SLAC. The analysis uses the SLD Cerenkov Ring Imaging Detector (CRID) for clean and efficient identification of charged tracks and significant background reduction. In addition, K{sup *0} production has been studied in quark and anti-quark jet samples, which were identified by their electroweak forward backward asymmetries using the SLD high electron beam polarization. A difference between the two samples is observed in the K{sup *0} rate at high momentum, consistent with leading particle and strangeness suppression hypotheses.
Date: August 1, 1996
Creator: Dima, Mihai & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Strange particle measurements from the EOS TPC

Description: A high statistics sample of {Lambda}`s produced in 2 GeV/nucleon {sup 5}8Ni + {sup nat}Cu collisions has been obtained with the EOS Time Projection Chamber at the Bevalac. The coverage of the EOS TPC is essentially 100% for y > y{sub cm} and extends down to P{sub T} = 0 where interesting effects such as collective radial expansion may be important. In addition, the detection of a majority of the charged particles in the TPC, along with the presence of directed flow for protons and heavier fragments at this beam energy, allows for the correlation of A production with respect to the event reaction plane. Our preliminary analysis indicates the first observation of a sidewards flow signature for A`s. Comparisons with the cascade code ARC are made.
Date: February 1, 1995
Creator: Justice, M.
Partner: UNT Libraries Government Documents Department

Lambda {sup 0} polarization in 800 GeV/c pp {r_arrow} p{sub f} ({Lambda}{sup 0} K{sup +})

Description: The authors report preliminary results from a study of {Lambda}{sup 0} polarization in the exclusive reaction pp {r_arrow} p{sub f} ({Lambda}{sup 0} K{sup +}) at 800 GeV/c. These data are a part of the 5 x 10{sup 9} diffractive event sample collected by Fermilab E690. They observe a large dependence of the polarization on the {Lambda}{sup 0} K{sup +} invariant mass. This observation confirms the result of the CERN ISR R608 experiment and extends the range over which the effect is observed.
Date: April 18, 2000
Creator: al., J. Felix et
Partner: UNT Libraries Government Documents Department

H{sub 0} candidates from the decays {Sigma}{sup {minus}}p and {Lambda}p{pi}{sup {minus}}, produced in heavy ion collisions Si beam on Pb target

Description: There is considerable interest in searching for strange quark matter (strangelets). The lowest strangelet state is thought to be a six quark dibaryon singlet spin zero state called the H{sub 0} predicted by R.L. Jaffe. The authors present H{sub 0} candidate events, where H{sub 0}(2210) is observed through the weak decay modes {Sigma}{sup {minus}}p and {Lambda}p{pi}{sup {minus}}, produced in central heavy ion collisions with 14.6 x A Gev/c Si beam on Pb target. The lifetime is consistent with {approximately}4 cm cr in both channels approximately 1/3 of an H{sub 0}(2210) which decays into {Sigma}{sup {minus}} p is produced per central Si Pb collision. The branching ratio between {Lambda}p{pi}{sup {minus}} and {Sigma}{sup {minus}}p is around 11% {+-} 3%.
Date: December 1, 1997
Creator: Longacre, R.S.
Partner: UNT Libraries Government Documents Department

The Structure of the Weak Interaction $lambda$ + N $Yields$ N + N

Description: Empirical evidence on the nonmesic decay of LAMBDA hypernuclei is analyzed in terms of the spin and isospin dependence of the weak interactions A + p yields n + p and LAMBDA + n yields n + n. The nonmesic decay rates for / sub LAMBDA /He/sup 4/ and /sub LAMBDA /H/sup 4/ were obtained by treating the A de-excitation by different nucleons as incoherent and assuming the validity of the DELTA I = 1/2 selection rule for these interactions. The ratios of nonmesic to pi /sup -/ decay modes and of the first reaction to the second were calculated as 1.68 plus or minus 0.36 and 0.5, respectively, for He/sup 6/ decay. The later ratio for H/sup 4/ was predicted to be 1/(8.8 plus or minus 3.2). Interpretation of the rates is discussed, and it is concluded that if the LAMBDA I = 1/2 rule holds for the LAMBDA -N yields N-N weak interaction and if present ideas about the current-current nature of weak interactions are valid, then the higher-order mesonic corrections to this primary four-fermion interaction must mask the simplicity of their primary form. (D.C.W.)
Date: May 1, 1963
Creator: Block, M. M. & Dalitz, R. H.
Partner: UNT Libraries Government Documents Department

Strangeness production as a function of centrality

Description: A correction to the TPC efficiency calculations based on discriminator response data is shown to have an average effect of 20% on the absolute magnitude of the earlier results. Consistency between runs with the NA36 magnet in different polarities is demonstrated. Comparisons are made with NA35 S + Ag data. The absolute flux of {Lambda} particles is approximately a factor of two in disagreement between the two experiments. A dependence of the rapidity spectrum for lambda`s on centrality is demonstrated.
Date: February 1, 1995
Creator: Greiner, D .E.
Partner: UNT Libraries Government Documents Department

Masses and branching fractions at CDF

Description: The authors present a collection of new results on b-meson and {Lambda}{sub b} masses and branching fractions measured at CDF. They have improved the measurement of the {Lambda}{sub b} and B{sub s} mass and they have measured the branching fractions of B{sub s} {yields} D{sub s}{pi}, {Lambda}{sub b} {yields} {Lambda}{sub c}{pi} and B{sub u} {yields} {Phi}K{sup {+-}}.
Date: October 30, 2003
Creator: D'Auria, S.
Partner: UNT Libraries Government Documents Department

Studies of the Rapid Beam Ejector at the Cosmotron

Description: Extraction of the external beam of the cosmotron with maximum efficiency and minimum duration for measurements of the magnetic moment of the lambda hyperon requires addition of a rapid beam ejector (RBE). Early experiments with the RBE give lower ejection efficiency than the standard ejection system. Reconstruction of the RBE with lengthening of the rise time of the system gives improved values. Computer studies that involve solving the equation of motion for the radial betatron oscillation with time increasing perturbation in one section yield information on particle distributions and result in increases of the turn spacings in RBE to prevent betatron oscillation distribution distortions. Ejection efficiency is now the same with and without the RBE. (D.C.W.)
Date: January 16, 1963
Creator: Barton, M. Q.; Kernan, W.; Novey, T.; Warshaw, S. & Wattenberg, A.
Partner: UNT Libraries Government Documents Department

Proposal to Study Multibody Final States in pp Collisions at 200 GeV/c Using the NAL 15-Foot Bubble Chamber

Description: We propose to expose the NAL 15-foot hydrogen bubble chamber to 200 GeV protons. We intend to take 20,000 pictures. Multiparticle final states will be studied by measuring the momenta of all charged final state particles with the exception of a few very fast tracks where at least the charge and the emission angle of the particle will be determined. Comparison with various models for high energy multiparticle production will be made. Additionally, K{sup o} and {Lambda} production will be studied as well as {pi}{sup o} production and the correlation between {pi}{sup o} and charged particles.
Date: October 27, 1972
Creator: Engelmann, R.; Lee-Franzini, J.; Moore, C.; Pratap, M. & /SUNY
Partner: UNT Libraries Government Documents Department