We investigate the sextet $b$-baryon decay processes $Ω_b\to J/ψΩ^{(*)}$,where $Ω^*$ represents the $1P$-, $1D$- and $2S$-wave excited $Ω$ hyperons in the spectroscopy. Using the constituent quark model, we obtain ${\cal B}(Ω_b \to J/ψΩ)=8.8\times 10^{-4}$, which agrees with the previous studies to the order of magnitude. By identifying $Ω(2012)$ as $Ω(1^2P_{3/2^-})$, ${\cal B}(Ω_b \to J/ψΩ(2012))=1.1\times 10^{-3}$ can be similarly significant. Additionally, $Ω(1^2D_{5/2^+})$ and $Ω(1^4D_{3/2^+},1^4D_{5/2^+})$ states exhibit production rates of 0.5, and (0.6, 0.8), respectively, relative to their ground-state counterpart. Notably, our findings suggest that ${\cal B}(Ω_b\to J/ψΩ(2^2S_{1/2^+},2^4S_{3/2^+}))$ are as large as $(4.5,20)\times 10^{-4}$, making them accessible to experiments at LHCb.
The spectrum of excited baryons in the $N$ = 2 band is reanalys9 pagesed in the $1/N_c$ expansion method, with emphasis on hyperons. Predictions are made for the classification of these excited baryons into SU(3) singlets, octets and decuplets.
The $1/N_c$ expansion method for studying the mass spectrum of excited baryons is shortly reviewed together with applications to mixed symmetric states. The $[{\bf 70, \ell^+}]$ multiplet, belonging to the $N$ = 2 band, is reanalyzed, with emphasis on hyperons and the SU(3) symmetry breaking operators entering the mass formula to first order. An important result is that the hierarchy of masses as a function of strangeness is correctly reproduced for all multiplets. Predictions for unknown excited hyperons to SU(6) $\times$ O(3) multiplets are made.
We comment on the recent evidence by the LHCb Collaboration for a structure in the $J/ψΛ$ final state produced in the decay $Ξ^-_b \to J/ψΛK^-$, with minimal quark content $c \bar c u d s$.
We report evidence for $N(1710)P_{11}$, $N(1875)P_{11}$, $N(1900)P_{13}$, $Δ(1600)P_{33}$, $Δ(1910)P_{31}$, and $Δ(1920)P_{33}$, and find indications that $N(1900)P_{13}$ might have a companion state at 1970\,MeV. The controversial $Δ(1750)P_{31}$ is not seen. The evidence is derived from a study of data on pion- and photo-induced hyperon production, but other data are included as well. Most of the resonances reported here were found in the Karlsruhe-Helsinki (KH84) and the Carnegie-Mellon (CM) analyses but were challenged recently by the Data Analysis Center at GWU. Our analysis is constraine…
We discuss the status of current dynamical lattice QCD simulations in connection to the emerging results on the strange and charmed baryon spectrum, excited states of the nucleon and the investigation of the structure of scalar mesons.
The chiral quark model gives a reasonably good description of many low-energy observables by incorporating the effective degrees carried by the constituent quarks and Goldstone bosons. We calculate the decuplet to octet transition magnetic moments and the decay widths of several excited hyperons using this model. The various radiative decay widths from the chiral quark roughly agree with experimental data including the recent JLAB measurement.
We provide an investigation of the P-wave hyperons employing the field correlator method in QCD. This method allows to derive the Effective Hamiltonian successfully applied to the meson and ground state baryon spectra. The hyperon spectrum appears to be expressed through two parameters relevant to QCD, the string tension σ, the strong coupling constant α_s, and the bare strange quark mass m_s. Using these parameters a unified description of the ground and excited hyperon states is achieved. We also briefly consider the nucleon P-wave excitations. In particular, we predict that both the nucleon…
Decays of heavy mesons and of heavy hyperons are used to provide tests of the standard model and information about new mixing schemes for the $η$ and $η^{'}$ mesons. These include the two body decays $B_s \to J / ψM$ and $B_d \to J / ψM$, $B \to η(η^{'})K(K^\ast)$ and $Λ_b \to Λη(η^{'})$, semileptonic $D$ decays, and properties of radially excited mesons.
Vector charmonium states $J/Ψ$ and $Ψ'$ are copiously produced by $e^+e^-$ annihilations at the Beijing Electron Positron Collider (BEPC). Their decays provide an excellent place for studying excited nucleons and hyperons -- $N^*$, $Λ^*$, $Σ^*$ and $Ξ^*$ resonances. The systematic study of these excited nucleons and hyperons can provide us with critical insights into the internal quark structure of baryons.
The electromagnetic decay processes of excited hyperon states are a very sensitive probe of the structure of hyperons. We will argue that the recent measurements of electromagnetic decay rates indicate that the wave functions of the hyperon ground states should contain sizeable components of excited quark states (configuration mixing). Flavor-SU(3) is a broken symmetry and it appears that the hyperon wave functions should preferably be written in a $uds$-basis, where only the light $u$ and $d$ quarks are symmetrized, and not in the usual SU(6)-basis.
This Workshop brought top experts, researchers, postdocs, and students from high-energy heavy ion interactions, lattice QCD and hadronic physics communities together. YSTAR2016 discussed the impact of "missing" hyperon resonances on QCD thermodynamics, on freeze-out in heavy ion collisions, on the evolution of early universe, and on the spectroscopy of strange particles. Recent studies that compared lattice QCD predictions of thermodynamic properties of quark-gluon plasma at freeze-out with calculations based on statistical hadron resonance gas models as well as experimentally measured ratios …
Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. $Λ_b$ , $Λ_c$ and $Ξ_c$ production rate and polarization at LEP energies are calculated and, where possible, compared with experiment. A different approach, also relying on a heavy quark-diquark model, is proposed for the small momentum transfer inclusive production of polarized heavy flavor hyperons. The predicted $Λ_c$ polarization is roughly in agreement with experiment.
An explanation of the difference in the values of the apparent $f/d$ ratios for the S- and P- wave amplitudes of nonleptonic hyperon decays is proposed. The argument is formulated in the framework of the standard pole model with $(56,0^{+})$ ground-state and $(70,1^{-})$ excited baryons as intermediate states for the P- and S- waves respectively. Under the assumption that the dominant part of the deviation of $(f/d)_{P-wave}$ from $-1$ is due to large quark sea effects, $SU(3)$ symmetry breaking in energy denominators is shown to lead to a prediction for $(f/d)_{S-wave}$ which is in excellent …
Hyperon non-leptonic decays in relativistic Chiral Perturbation Theory with resonances
University of Silesia in Katowice（卡托维兹西里西亚大学）；GSI Helmholtzzentrum für Schwerionenforschung GmbH（GSI亥姆霍兹重离子研究中心有限公司）；Uppsala universitet（乌普萨拉大学）；National Centre for Nuclear Research（国家核研究中心）
Electroweak Transitions of Hyperons and Charmed Baryons: Opportunities and Prospects
Uppsala University（乌普萨拉大学）；National Centre for Nuclear Research（国家核研究中心）；University of Cyprus（塞浦路斯大学）；The Cyprus Institute（塞浦路斯研究所）；Institute of High Energy Physics（高能物理研究所）；Lund University（隆德大学）；École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）；University of Graz（格拉茨大学）
The detection of radially excited heavy meson \\states in recent years and measurement of heavy meson decays, particularly $B_c^+\to J/ψD_s^+$ and $B_c^+\to J/ψD_s^{*+}$, by the LHCb and ATLAS Collaborations, have aroused a lot of theoretical interest in the nonleptonic decays of $b$-flavored mesons. In this paper, we study the exclusive two-body nonleptonic $\bar{B}^0$, $\bar{B_s^0}$, $B^-$ and $B_c^-$-meson decays to two vector meson ($V_1(nS)V_2$) states. Assuming the factorization hypothesis, we calculate the weak-decay form factors from the overlapping integrals of meson wave functions, i…
The fragmentation of excited hypernuclear system formed in heavy ion collisions has been described by the canonical thermodynamical model extended to three component systems. The multiplicity distribution of the fragments has been analyzed in detail and it has been observed that the hyperons have the tendency to get attached to the heavier fragments. Another important observation is the phase coexistence of the hyperons, a phenomenon which is linked to liquid gas phase transition in strange matter.
The classical quenched quark models with three constituent quarks provide a good description for the baryon spatial ground states, but fail to reproduce the spectrum of baryon excited states. More and more evidences suggest that unquenched effects with multi-quark dynamics are necessary ingredients to solve the problem. Several new hyperon resonances reported recently could fit in the picture of penta-quark states. Based on this picture, some new hyperon excited states were predicted to exist; meanwhile with extension from strangeness to charm and beauty, super-heavy narrow $N^*$ and $Λ^*$ res…
In this contribution we discuss recent results in light quark baryon spectroscopy involving CLAS data and higher level analysis results from the partial wave analysis by the Bonn-Gatchina group. New baryon states were discovered largely based on the open strangeness production channels $γp \to K^+ Λ$ and $γp \to K^+ Σ^0$. The data illustrate the great potential of the kaon-hyperon channel in the discovery of higher mass baryon resonances in s-channel production. Other channels with discovery potential, such as $γp \to p ω$ and $γp \to ϕp$ are also discussed. In the second part I will demonstra…
In this work we study the possible QCD exotic states in the doubly charmed baryon sector. Within chiral effective theory, it is predicted that several excited baryons result from the $S$-wave scattering of ground-state doubly charmed baryons ($Ξ_{cc}^{++}, Ξ_{cc}^{+}, Ω_{cc}^{+}$) and light pseudoscalar mesons ($π, K, η$). The excited doubly charmed baryons can be classified by the strangeness ($S$) and isospin ($I$) quantum numbers. Two of the excited states are clearly exotic, in the sense that they cannot be explained by the conventional baryons with three quarks, since their quantum number…
At LHC a large number of b-flavored baryons will be produced. In this note we propose new baryon modes to determine the photon helicity of the penguin transition $b \to s γ$. The decay $Λ_b \to Λγ$ has the drawback that the $Λ$, being neutral and long-lived, will escape detection most of the time. To overcome this difficulty, transitions of the type $Λ_b \to Λ^{*} γ$ have been proposed, where $Λ^{*}$ denotes an excited state decaying strongly within the detector into the clean mode $p K^-$. The doublet $Ξ_b$, that decays weakly, has a number of good features. The charged baryon $Ξ_b^-$ will de…
In this article, we review the HAL QCD method to investigate baryon-baryon interactions such as nuclear forces in lattice QCD. We first explain our strategy in detail to investigate baryon-baryon interactions by defining potentials in field theories such as QCD. We introduce the Nambu-Bethe-Salpeter (NBS) wave functions in QCD for two baryons below the inelastic threshold. We then define the potential from NBS wave functions in terms of the derivative expansion, which is shown to reproduce the scattering phase shifts correctly below the inelastic threshold. Using this definition, we formulate …
