Search results for "hyperon"
showing 10 items of 118 documents
Spin, parity and nature of the Xi(1620) resonance
2002
Using a unitary extension of chiral perturbation theory with a lowest-order s -wave SU(3) chiral Lagrangian we study low-energy meson-baryon scattering in the strangeness S = − 2 sector. A scattering-matrix pole is found around 1605 MeV which corresponds to an s -wave Ξ resonance with J P = 1 / 2 − . We identify this resonance with the Ξ ( 1620 ) state, quoted by the Particle Data Group with I = 1 / 2 but with unknown spin and parity. The addition of the S = − 2 state to the recently computed Λ ( 1670 ) , Σ ( 1620 ) , and N ( 1535 ) states completes the octet of J P = 1 / 2 − resonances dynamically generated in this chiral unitary approach.
Exploring the potential of antihyperons in nuclei with antiprotons
2008
A simple method to explore the interaction of antihyperons in nuclei by exclusive hyperon-antihyperon pair production close to threshold in antiproton nucleus interactions is proposed. Due to energy and momentum conservation event-by-event transverse momentum correlations of the produced hyperons and antihyperons contain information on the difference between their potentials. A schematic Monte Carlo simulation is used to illustrate the sensitivities of the proposed method for the reaction 1.66GeV/c antiproton+$^{12}$C $\to {\Lambda\bar{\Lambda}}$. For produced D-meson pairs at 6.7GeV/c the sensitivity of the transverse momenta correlation will probably be to small to deduce differences betw…
Study of Σ(1385) and Ξ(1321) hyperon and antihyperon production in deep inelastic muon scattering
2013
Large samples of \Lambda, \Sigma(1385) and \Xi(1321) hyperons produced in deep-inelastic muon scattering off a ^6LiD target were collected with the COMPASS experimental setup at CERN. The relative yields of \Sigma(1385)^+, \Sigma(1385)^-, \bar{\Sigma}(1385)^-, \bar{\Sigma}(1385)^+, \Xi(1321)^-, and \bar{\Xi}(1321)^+ hyperons decaying into \Lambda(\bar{\Lambda})\pi were measured. The heavy hyperon to \Lambda and heavy antihyperon to \bar{\Lambda} yield ratios were found to be in the range 3.8% to 5.6% with a relative uncertainty of about 10%. They were used to tune the parameters relevant for strange particle production of the LEPTO Monte Carlo generator.
Regge signatures from CLAS Λ(1520) photoproduction data at forward angles
2014
The γp→K+Λ(1520) reaction mechanism is investigated within a Regge-effective Lagrangian hybrid approach based on our previous study of this reaction [Phys. Rev. C 89, 015203 (2014)PRVCAN0556-281310.1103/PhysRevC.89.015203]. Near threshold and for large K+ angles, the data from both the Continuous Electron Beam Accelerator Facility large acceptance spectrometer (CLAS) and the laser electron photon beamline at SPring-8 (LEPS) can be successfully described by considering the contributions from the contact, t-channel K¯ exchange, u-channel Λ(1115) hyperon pole, and s-channel nucleon pole and N*(2120) resonance contributions. However, for higher energies and forward K+ angles, systematic discrep…
Re-analysis of theΛ(1520)photoproduction reaction
2014
Based on previous studies that support the important role of the N*(2120)D-13 resonance in the gamma p -> K+ A(1520) reaction, we make a re-analysis of this A(1520) photoproduction reaction taking into account the recent CLAS differential cross-section data. In addition to the contact, t-channel (K) over bar exchange, s-channel nucleon pole, and N*(2120) [previously called N*(2080)] resonance contributions, which have been considered in previous works, we also study the u-channel A(1115) hyperon pole term. The latter mechanism has always been ignored in all theoretical analysis, which has mostly relied on the very forward K+ angular LEPS data. It is shown that when the contributions from th…
Charm and Hidden Charm Scalar Resonances in Nuclear Matter
2009
18th Particles and Nuclei International Conference (PANIC08). Eilat, ISRAEL, NOV 09-14, 2008
Multi-strange baryon production in p Pb collisions at sNN=5.02 TeV
2016
The multi-strange baryon yields in Pb--Pb collisions have been shown to exhibit an enhancement relative to pp reactions. In this work, $\Xi$ and $\Omega$ production rates have been measured with the ALICE experiment as a function of transverse momentum, ${p_{\rm T}}$, in p-Pb collisions at a centre-of-mass energy of ${\sqrt{s_{\rm NN}}}$ = 5.02 TeV. The results cover the kinematic ranges 0.6 GeV/$c<{p_{\rm T}} <$7.2 GeV/$c$ and 0.8 GeV/$c<{p_{\rm T}}<$ 5 GeV/$c$, for $\Xi$ and $\Omega$ respectively, in the common rapidity interval -0.5 $<{y_{\rm CMS}}<$ 0. Multi-strange baryons have been identified by reconstructing their weak decays into charged particles. The ${p_{\rm T}}$ spectra are ana…
Semileptonic decays of the lightJP=1/2+ground state baryon octet
2008
We calculate the semileptonic baryon octet-octet transition form factors using a manifestly Lorentz covariant quark model approach based on the factorization of the contribution of valence quarks and chiral effects. We perform a detailed analysis of SU(3)-breaking corrections to the hyperon semileptonic decay form factors. We present complete results on decay rates and asymmetry parameters including lepton mass effects for the rates.
Observation of Coulomb-Assisted Nuclear Bound State of Ξ−–N14 System
2021
In an emulsion-counter hybrid experiment performed at J-PARC, a Ξ^{-} absorption event was observed which decayed into twin single-Λ hypernuclei. Kinematic calculations enabled a unique identification of the reaction process as Ξ^{-}+^{14}N→_{Λ}^{10}Be+_{Λ}^{5}He. For the binding energy of the Ξ^{-} hyperon in the Ξ^{-}-^{14}N system a value of 1.27±0.21 MeV was deduced. The energy level of Ξ^{-} is likely a nuclear 1p state which indicates a weak ΞN-ΛΛ coupling.
Properties of hyperons in chiral perturbation theory
2009
The development of chiral perturbation theory in hyperon phenomenology has been troubled due to power-counting subtleties and to a possible slow convergence. Furthermore, the presence of baryon-resonances, e.g. the lowest-lying decuplet, complicates the approach, and the inclusion of their effects may become necessary. Recently, we have shown that a fairly good convergence is possible using a renormalization prescription of the loop-divergencies which recovers the power counting, is covariant and consistent with analyticity. Moreover, we have systematically incorporated the decuplet resonances taking care of both power-counting and $consistency$ problems. A model-independent understanding o…