Search results for "hyperon"
showing 10 items of 118 documents
Maximal isospin few-body systems of nucleons and $\Xi$ hyperons
2016
By using local central Yukawa-type interactions that reproduce the low-energy parameters of the latest updates of the Nijmegen ESC08c potentials we show that the $N\Xi$, $NN\Xi$, $N\Xi\Xi$ and $NN\Xi\Xi$ systems with maximal isospin are bound. Since in these states the strong decay $N\Xi\to\Lambda\Lambda$ is forbidden by isospin conservation, these strange few-body systems will be stable under the strong interaction. These results may suggest that other states with different number of $N$'s and $\Xi$'s in the maximal isospin channel could also be bound.
Measurement of the Ξ0→Λγ decay asymmetry and branching fraction
2004
In data taken with the NA48 experiment at the CERN SPS in 1999, 730 candidates of the weak radiative hyperon decay Ξ0→Λγ have been found with an estimated background of 58±8 events. From these events the Ξ0→Λγ decay asymmetry has been determined to α(Ξ0→Λγ)=-0.78±0.18stat±0.06 syst, which is the first evidence of a decay asymmetry in Ξ 0→Λγ. The branching fraction of the decay has been measured to be Br(Ξ0→Λγ)=(1.16±0.05 stat±0.06syst)×10-3. © 2004 Elsevier B.V. All rights reserved.
Weak production of strange Ξ baryons off the nucleon
2019
The authors would like to thank Luis Alvarez-Ruso and Manuel Jose Vicente Vacas for useful discussions. One of the authors (MRA) would like to thank the pleasant hospitality at University of Granada where part of the work has been done.
Physical observables in the decay Λb→Λc(→Λ+π)+τ−+ν̄τ
2015
We analyze the tauonic semileptonic baryon decays [Formula: see text] with particular emphasis on the lepton helicity flip contributions which vanish for zero lepton masses. We calculate the total rate, differential decay distributions, the longitudinal and transverse polarization components of the [Formula: see text] and the [Formula: see text], and the lepton-side forward-backward asymmetries. We use the covariant confined quark model to provide numerical results on these observables.
Chiral extrapolation and finite-volume dependence of the hyperon vector couplings
2014
The hyperon vector form factors at zero momentum transfer, $f_1(0)$, play an important role in a precise determination of the Cabibbo-Kobayashi-Maskawa matrix element $V_{us}$. Recent studies based on lattice chromodynamics (LQCD) simulations and covariant baryon chiral perturbation theory yield contradicting results. In this work, we study chiral extrapolation of and finite-volume corrections to the latest $n_f=2+1$ LQCD simulations. Our results show that finite-volume corrections are relatively small and can be safely ignored at the present LQCD setup of $m_\pi L=4.6$ but chiral extrapolation needs to be performed more carefully. Nevertheless, the discrepancy remains and further studies a…
Measurement of the transverse polarization ofΛandΛ¯hyperons produced in proton-proton collisions ats=7 TeVusing the ATLAS detector
2015
The transverse polarization of Λ and Λ¯ hyperons produced in proton-proton collisions at a center-of-mass energy of 7 TeV is measured. The analysis uses 760 μb−1 of minimum bias data collected by the ATLAS detector at the LHC in the year 2010. The measured transverse polarization averaged over Feynman xF from 5×10−5 to 0.01 and transverse momentum pT from 0.8 to 15 GeV is −0.010±0.005(stat)±0.004(syst) for Λ and 0.002±0.006(stat)±0.004(syst) for Λ¯. It is also measured as a function of xF and pT, but no significant dependence on these variables is observed. Prior to this measurement, the polarization was measured at fixed-target experiments with center-of-mass energies up to about 40 GeV. …
Compositeness of the strange, charm and beauty odd parity $\Lambda$ states
2015
14 pages.- 2 figures.- 5 tables
Exotic hyperons: Theoretical status and search perspectives in hyperon beam facilities
1992
The theoretical models that predict the existence of exotic hyperons made of more than three quarks are reviewed. We present the properties of exotic hyperons with strangenessS=−1 (quark contents $$sqqq\bar q$$ ),S=−2 ( $$ssqq\bar q$$ ) andS=−3 ( $$sssq\bar q$$ ) predicted by the sum rules for reggeon-particle scattering amplitudes. The inclusive cross sections for the production of these hyperons in hyperon-proton interactions are calculated. The cross sections turn out to be of the order of millibarns, thus opening a good perspective to encounter such exotic hyperons in the available hyperon beam facilities at CERN and FNAL. We also propose to study the Regge trajectories corresponding to…
Spin, helicity and flavour patterns in exclusive decays of bottom mesons into baryon-antibaryon pairs
1989
I use the constituent quark model to calculate the exclusive decays of bottom mesons into ground state baryon-antibaryon pairs mediated by the weakb→c and b→u transitions. TheW-exchange contributions to these decays are found to be negligible. For theW-decay contributions I find that the simple colour-flavour structure of the 1/2+ and 3/2+ ground state baryons together with the current-current nonleptonic Hamiltonian leads to many simple and testable predictions. Notable among these is the predicted vanishing of decays involving 3/2+ baryons as in\(\overline {B^0 } (B^ - ) \to 3/2^ + \overline {1/2^ + } \) and\(\overline {B^0 } (B^ - ) \to 3/2^ + \overline {3/2^ + } \). An experimental veri…
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.