Search results for "hyperon"
showing 10 items of 118 documents
Observation of the Doubly StrangebBaryonΩb−
2008
We report the observation of the doubly strange b baryon Omega(-)(b) in the decay channel Omega(-)(b) -> J/psi Omega(-), with J/psi -> mu(+)mu(-) and Omega(-) -> Lambda K- -> (p pi(-))K-, in p (p) over bar collisions at root s = 1.96 TeV. Using approximately 1.3 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider, we observe 17.8 +/- 4.9(stat) +/- 0.8(syst) Omega(-)(b) signal events at a mass of 6.165 +/- 0.010(stat) +/- 0.013(syst) GeV. The significance of the observed signal is 5.4 sigma, corresponding to a probability of 6.7 x 10(-8) of it arising from a background fluctuation.
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.
Hyperon Semileptonic Decays and CKM Unitarity
2005
We perform a new numerical analysis of hyperon semileptonic decays emphasizing the systematic uncertainties. The poor understanding of SU(3) symmetry breaking effects at second order in the vector form factor translates into a large error of |V(us)|. Using our determination |V(us)| = 0.226 +/- 0.005 together with those coming from other sources we test the unitarity of the CKM matrix.
Constituent quark model study of light- and strange-baryon spectra
2005
We investigate the structure of the SU(3) octet and decuplet baryons employing a constituent quark model designed for the study of the baryon-baryon interaction and successfully applied to the meson spectra. The model considers through the interacting potential perturbative, one-gluon exchange, and non-perturbative, boson exchanges and confinement, aspects of the underlying theory, QCD. We solve the three-quark problem by means of the Faddeev method in momentum space. We analyze the effect of the different terms in the interaction and make contact with the use of relativistic kinematics. We find an explanation to the strong contribution of the pseudoscalar forces in the semirelativistic app…
Investigation of the p–Σ0 interaction via femtoscopy in pp collisions
2020
This Letter presents the first direct investigation of the p–Σ0 interaction, using the femtoscopy technique in high-multiplicity pp collisions at s=13 TeV measured by the ALICE detector. The Σ0 is reconstructed via the decay channel to Λγ, and the subsequent decay of Λ to pπ−. The photon is detected via the conversion in material to e+e− pairs exploiting the capability of the ALICE detector to measure electrons at low transverse momenta. The measured p–Σ0 correlation indicates a shallow strong interaction. The comparison of the data to several theoretical predictions obtained employing the Correlation Analysis Tool using the Schrödinger Equation (CATS) and the Lednický–Lyuboshits approach s…
BaBar Results on Hadronic Cross Sections with Initial State Radiation
2008
In this paper we present recent results of the BaBar experiment at the B-factory PEP-II in the field of hadronic cross section measurements. At PEP-II, which is designed for a fixed center-of-mass energy around the ϒ(4S) resonance, the hadronic cross section is measured using events with Initial State Radiation (ISR), which allows the cover the entire energy range below 4 GeV in one single experiments. Results for exclusive finals states with 3, 4 and 5 hadrons, as well as measurements of hyperon form factors are shown.
Antineutrino induced Λ(1405) production off the proton
2015
We have studied the strangeness-changing antineutrino-induced reactions ${\overline{\ensuremath{\nu}}}_{l}p\ensuremath{\rightarrow}{l}^{+}\ensuremath{\phi}B$, with $\ensuremath{\phi}B={K}^{\ensuremath{-}}p$, ${\overline{K}}^{0}n$, ${\ensuremath{\pi}}^{0}\ensuremath{\Lambda}$, ${\ensuremath{\pi}}^{0}{\ensuremath{\Sigma}}^{0}$, $\ensuremath{\eta}\ensuremath{\Lambda}$, $\ensuremath{\eta}{\ensuremath{\Sigma}}^{0}$, ${\ensuremath{\pi}}^{+}{\ensuremath{\Sigma}}^{\ensuremath{-}}$, ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\Sigma}}^{+}$, ${K}^{+}{\ensuremath{\Xi}}^{\ensuremath{-}}$, and ${K}^{0}{\ensuremath{\Xi}}^{0}$, using a chiral unitary approach. These ten coupled channels are allowed t…
Vector current conservation and neutrino emission from singlet-paired baryons in neutron stars
2006
Neutrino emission caused by singlet Cooper pairing of baryons in neutron stars is recalculated by accurately taking into account for conservation of the vector weak currents. The neutrino emissivity via the vector weak currents is found to be several orders of magnitude smaller than that obtained before by different authors. This makes unimportant the neutrino radiation from singlet pairing of protons or hyperons.
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…
The radiative decay of the Lambda(1405) and its two-pole structure
2007
We evaluate theoretically the radiative decay widths into $\gamma\Lambda$ and $\gamma\Sigma^0$ of the two poles of the $\Lambda(1405)$ found in chiral unitary theories and we find quite different results for each of the two poles. We show that, depending on which reaction is used to measure the $\Lambda(1405)$ radiative decays, one gives more weight to one or the other pole, resulting in quite different shapes in the $\gamma\Lambda(\Sigma^0)$ invariant mass distributions. Our results for the high-energy pole agree with those of the empirical determination of the $\gamma\Lambda$ and $\gamma\Sigma^0$ radiative widths (based on an isobar model fitting of the $K^-p$ atom data), which are someti…