This work considers $K^0, \bar K^0$ meson mixings and oscillations via $K^0_1, K^0_2$ meson states at strangeness violation by weak interactions in two cases - without and with taking into account $K^0_1, K^0_2$ meson decays. In the first case the oscillation theory correctly describes $K^o, \bar K^o \to K^o, \bar K^o$ transition processes. In the second case, when we take into account meson decays, the oscillation theory cannot correctly describe this process at long distances since mainly $K^o_2$ mesons remain at long distances therefore the condition for oscillations is absent. So, at long distances in this process only long living $K^0_2$ mesons are present but not $K^o, \bar K^o$ mesons.
We derive strangeness -2 baryon-baryon interactions from a chiral constituent quark model including the full set of scalar mesons. The model has been tuned in the strangeness 0 and -1 two-baryon systems, providing parameter free predictions for the strangeness -2 case. We calculate elastic and inelastic $NΞ$ and $ΛΛ$ cross sections which are consistent with the existing experimental data. We also calculate the two-body scattering lengths for the different spin-isospin channels.
In this article, we investigate the $\bar{D}Σ_c$, $\bar{D}Ξ^\prime_c$, $\bar{D}Σ_c^*$, $\bar{D}Ξ_c^*$, $\bar{D}^{*}Σ_c$, $\bar{D}^{*}Ξ^\prime_c$, $\bar{D}^{*}Σ_c^*$ and $\bar{D}^{*}Ξ_c^*$ pentaquark molecular states with strangeness and without strangeness via the QCD sum rules at length, pay much attention to the light flavor $SU(3)$ breaking effects, and make predictions for new pentaquark molecular states besides assigning the $P_c(4312)$, $P_c(4380)$, $P_c(4440)$, $P_c(4457)$ and $P_{cs}(4459)$ self-consistently. We can search for those pentaquark molecular states in the decays of the $Λ_b…
The strange quark contributions to the electromagnetic form factors of the proton are ideal quantities to study the role of hidden flavor in the properties of the proton. This has motivated intense experimental measurements of these form factors. A major remaining source of systematic uncertainty in these determinations is the assumption that charge symmetry violation (CSV) is negligible. We use recent theoretical determinations of the CSV form factors and reanalyse the available parity-violating electron scattering data, up to $Q^2$ $\sim$ 1 GeV$^2$. Our analysis considers systematic expansio…
Here we investigate the decay patterns of the low-lying hidden strangeness nucleon resonances ($\equiv N_{s\bar{s}}$) to the strangeness channels by employing the chiral Lagrangian approach, where the $N_{s\bar{s}}$ states are treated as compact pentaquark states. The $S$-wave decays of these states to the $PB$ (pseudoscalar meson and baryon) and $VB$ (vector meson and baryon) channels are studied. According to the obtained masses and decay properties, we find four states, namely, $N_{s\bar{s}}(1874)$ with quantum numbers $I(J^{P})=1/2(1/2^{-})$, $N_{s\bar{s}}(1885)$ with $I(J^{P})=1/2(3/2^{-}…
In the paper, we construct eight color singlet-singlet type five-quark currents with distinguished isospins to study the $\bar{D}Ξ^{\prime}$, $\bar{D}Ξ_c^{*}$, $\bar{D}^{*}Ξ_c^{\prime}$ and $\bar{D}^{*}Ξ_c^{*}$ molecular states with strangeness via the QCD sum rules. Numerical results show that the central values of the pentaquark masses with higher (lower) isospin are slightly above (below) the thresholds of the corresponding meson-baryon pairs, and support assigning the $P_{cs}(4459)$ as the $\bar{D}Ξ_c^{*}$ molecular state with the quantum numbers $IJ^P=0{\frac{3}{2}}^-$. The other predicti…
The CLAS Collaboration recently reported measured ratios of pion and kaon electroproduction cross sections from a proton target and extracted the ratios for light and strange quark--antiquark pairs, ${u\bar{u}}/ {d\bar{d}}$ and ${s\bar{s}}/ {d\bar{d}}$. Within an extended chiral constituent quark formalism, we investigate contributions to those ratios from the nonperturbative mechanism due to all possible intrinsic $|uudQ \bar{Q}\rangle$ Fock states in the proton; with $Q \bar{Q} \equiv u\bar{u},~ d\bar{d},~s\bar{s},~c\bar{c}$. Our results are compared with the CLAS data and findings from othe…
The interaction of the pseudoscalar meson and the baryon octet is investigated by solving the Bethe-Salpeter equation in the infinite and finite volume respectively. It is found that there is a resonance state generated dynamically, which owns a mass about 1550MeV and a large decay width of 120-200MeV. This resonance state couples strongly to the $πΞ$ channel. Therefore, it might not correspond to the $Ξ(1620)$ particle announced by Belle collaboration. At the same time, this problem is studied in the finite volume, and an energy level at 1570MeV is obtained, which is between the $πΞ$ and $\ba…
Strange and charmed baryon productions from proton-antiproton collisions are studied in the effective Lagrangian and Regge approaches. We include only the $t$-channel dynamics which is dominant for the diffractive region that is relevant in the present discussions. For strangeness productions, the coupling constants for $K$ meson are determined by $SU(3)$ relations while other unknown parameters for $K^{*}$ couplings and for form factors are fixed by existing observed data for strangeness productions. By extrapolating the amplitudes for strangeness productions to those for charm, we predict ch…
Strangeness suppression, the $ϕ$ meson and $Λ\barΛ$ spin correlations from exact strangeness conservation at the quark level
INFN, Sezione di Catania（意大利国家核物理研究所卡塔尼亚分部）；Faculty of Mathematics and Physics, Charles University（查理大学数学与物理学院）；Fakultät für Physik, Universität Bielefeld（比勒费尔德大学物理学院）
The existence of pentaquarks with strangeness content zero and one are major discoveries of the latest years in hadron physics. Most of these states can be understood as hadronic molecules and were predicted prior to their discovery within a model based on unitarized meson-baryon amplitudes obtained from vector meson exchange interactions. Contrary to earlier statements, we show this model to also predict the existence of pentaquarks with double strangeness, at about 4500 MeV and 4600 MeV, which are generated in a very specific and unique mechanism, via an attraction induced by a strong coupli…
We describe the electroproduction ratios of baryon-meson states from nucleon, inferring from the sea quarks in the nucleon using an extension of the quark model that takes into account the sea. As a result we provide, with no adjustable parameters, the predictions of ratios of exclusive meson-baryon final states:$ΛK^+$, $Σ^{*}K$, $ΣK$, $pπ^0$, and $nπ^+$. These predictions are in agreement with the new Jlab experimental data showing that sea quarks play an important role in the electroproduction. We also predicted further ratios of exclusive reactions that can be measured and tested in future …
It is suggested that the recently observed enhancement of the relative yield in $e^+e^-$ annihilation of states with hidden charm and hidden strangeness above 4.43\,GeV is associated with the $S$ wave production of the charmed strange meson pairs $D_{s0}(2317) \bar D_s^* + {\rm c.c.}$ and $D_{s1}^*(2460) \bar D_s+ {\rm c.c.}$. This mechanism implies a pattern of breaking of the Heavy Quark Spin Symmetry (HQSS) that can be tested in the final channels such as $η_c(1S) ϕ$, $h_c(1P) η$, $h_c(1P) η' $ produced in the same energy range.
Studies of the baryon-baryon interaction involving hyperons within chiral effective field theory, so far performed up to next-to-leading order (NLO) in the chiral expansion, have shown that for the strangeness $S=-1$ ($ΛN$, $ΣN$) and $S=-2$ ($ΛΛ$, $ΞN$) sectors a consistent and satisfactory description of the available scattering data and experimental constraints can be achieved based on the assumption of broken SU(3) flavor symmetry. We explore the possible extension of this approach at the NLO level to strangeness $S=-3$ and $S=-4$ baryon-baryon systems where empirical information is rather …
Recently, some progresses have been made on the double-heavy tetraquarks in the experiments, such as $T_{cc}$ reported by LHCb Collaboration, and $X_{cc\bar{s}\bar{s}}$ reported by the Belle Collaboration. Coming on the heels of our previous work about $T_{cc}$ and $T_{bb}$, we present a study on the bound states and the resonant states of its companions $QQ\bar{q}\bar{s}$ ($Q=c,b; q=u, s$) tetraquarks with strange flavor in the chiral quark model. Two pictures, one with meson-meson picture, another with diquark-antidiquark picture and their couplings are considered in our calculations. Isospi…
We present results from a chiral soliton model calculation for the spectrum of baryons with a single heavy quark (charm or bottom) and non-zero strangeness. We treat the strange components within a three flavor collective coordinate quantization of the soliton that fully accounts for light flavor symmetry breaking. Heavy baryons emerge by binding a heavy meson to the soliton. The dynamics of this heavy meson is described by the heavy quark effective theory with finite mass effects included.
The threshold behavior of $e^+ e^-$ annihilation is considered in the channels $B_{s0} \bar B_s^* + c.c.$, $B_{s1} \bar B_s + c.c.$, and $B_{s1} \bar B_s^* +c.c.$, where $B_{s0}$ and $B_{s1}$ are the excited bottom-strange $J^P=0^+$ and $J^P = 1^+$ mesons. It is argued that due to the heavy quark spin symmetry (HQSS) only one coherent combination of the first two channels is produced in the $S$ wave as well as the third channel. Thus, if there exist threshold molecular peaks in the considered channels, only two of such peaks can be formed in the annihilation. The properties of such threshold s…
Motivated by the successful interpretation of these observed $P_c$ and $P_{cs}$ states under the meson-baryon molecular picture, we systematically investigate the possible hidden-charm molecular pentaquark states with triple strangeness which is due to the $Ω_{c}^{(*)}\bar{D}_s^{(*)}$ interactions. We perform a dynamical calculation of the possible hidden-charm molecular pentaquarks with triple strangeness by the one-boson-exchange model, where the $S$-$D$ wave mixing effect and the coupled channel effect are taken into account in our calculation. Our results suggest that the $Ω_{c}\bar D_s^*$…
The meson-baryon interactions in s-wave in the strangeness S=-1 sector are studied using a chiral unitarity approach based on the next-to-leading order chiral SU(3) Lagrangian. The model is fitted to the large set of experimental data in different two-body channels. Particular attention is paid to the $Ξ$ hyperon production reaction, $\bar{K} N \rightarrow K Ξ$, where the effect of the next-to-leading order terms in the Lagrangian play a crucial role, since the cross section of this reaction at tree level is zero.
We calculate the inclusive production of a polarized $Λ$ or $\barΛ$ hyperon from the single longitudinally polarized proton and proton ($pp$) collision at RHIC. By comparing the data reported by the STAR Collaboration, we find that this process is sensitive to the polarization of strange and antistrange quarks of the proton in the experimental range. By introducing asymmetric coefficients with the minimization of $χ^2$, we further identify the asymmetry of the polarized strange-antistrange quarks in the proton sea and find that the first moment is $Δs \approx -0.025\pm 0.019$ for strange quark…
Motivated by the recent discovery of the first hidden charm pentaquark state with strangeness $P_{cs}(4459)$ by the LHCb Collaboration, we study the likely existence of a three-body $Σ_{c}\bar{D}\bar{K}$ bound state, which shares the same minimal quark content as $P_{cs}(4459)$. The $Σ_{c}\bar{D}$ and $DK$ interactions are determined by reproducing $P_c(4312)$ and $D_{s0}^*(2317)$ as $Σ_c\bar{D}$ and $\bar{D}\bar{K}$ molecules, respectively, while the $Σ_c\bar{K}$ interaction is constrained by chiral effective theory. We indeed find a three-body bound state by solving the Schrödinger equation …
Inspired by the recent evidence of $P_{cs}(4459)$ reported by LHCb, we continue to perform the investigation of hidden-charm molecular pentaquarks with double strangeness, which are composed of an $S$-wave charmed baryon $Ξ_c^{(\prime,*)}$ and an $S$-wave anti-charmed-strange meson $\bar{D}_s^{(*)}$. Both the $S$-$D$ wave mixing effect and the coupled channel effect are taken into account in realistic calculation. A dynamics calculation shows that there may exist two types of hidden-charm molecular pentaquark with double strangeness, i.e., the $Ξ_{c}^{*}\bar D_s^*$ molecular state with $J^P={5…
Impact of Baryon anti-Baryon annihilation on hyperon ($Λ$, $\barΛ$) production and apparent strangeness enhancement in $\barΛ/\bar{p}$ in heavy ion collisions at SPS energy
Variable Energy Cyclotron Centre（可变能量回旋加速器中心）；Homi Bhabha National Institute（霍米·巴巴国立研究所）
Decay properties of multi-strangeness $Ξ$ and $Ω$ baryon resonances are investigated within the constituent quark model by including relativistic corrections. The strong decay widths of various $Ξ$ and $Ω$ resonances are computed and tested for internal quark configurations to pin down their spin-parity ($J^P$) quantum numbers and internal structures. We found that the Roper-like resonances in the multi-strangeness sector have large decay widths bearing resemblances to their siblings in light and heavy baryon sectors. In addition, we obtained the decay ratio for the $Ω(2012)$ as $Γ{(Ω\to Ξ\bar…
A first measurement of time-reversal (T) asymmetries that are not also CP asymmetries has been recently achieved by the BaBar collaboration. We analyze the measured asymmetries in the presence of direct CP violation, CPT violation, wrong strangeness decays and wrong sign semileptonic decays. We note that the commonly used S_{ψK} and C_{ψK} parameters are CP-odd, but have a T-odd CPT-even part and a T-even CPT-odd part. We introduce parameters that have well-defined transformation properties under CP, T and CPT. We identify contributions to the measured asymmetries that are T conserving. We exp…
The interaction of the pseudoscalar meson and the baryon octet is investigated by solving the Bethe-Salpeter equation in the unitary coupled-channel approximation, In addition to the Weinberg-Tomozawa term, the contribution of the $s-$ and $u-$ channel potentials in the S-wave approximation are taken into account. In the sector of isospin $I=1/2$ and strangeness $S=0$, a pole is detected in the reasonable region on the complex energy plane of $\sqrt{s}$ in the center of mass frame by analyzing the behavior of the scattering amplitude, which is higher than the $ηN$ threshold and lies on the thi…
We present novel rope hadronization results for strange hadron enhancement in pp, pPb, and PbPb collisions using PYTHIA/Angantyr at LHC energies. With the rope model for string fragmentation, we find that the strangeness and baryon enhancement has a coherent increase across all collision systems as a function of average charged central multiplicity, in qualitative agreement with LHC data. In AA collisions, we find that the baryonic yields overshoot data at high multiplicities, and we discuss how a combination of rope hadronization with other string interactions may tame this rise.
We study the s-wave I=2 πΣand I=1 KN interactions from 2+1 flavor full lattice QCD simulation for relatively heavy quark mass corresponding to m_π=700 MeV. The s-wave meson-baryon potentials are obtained from the Nambu-Bethe-Salpeter amplitudes. Potentials in both channels reveal short range repulsions, which suggest the importance of the Pauli blocking effect. The I=1 KN scattering phase shifts are calculated and compared with the existing experimental data.
The results of the microscopic transport calculations of $\bar p$-nucleus interactions within a GiBUU model are presented. The dominating mechanism of hyperon production is the strangeness exchange processes $\bar K N \to Y π$ and $\bar K N \to ΞK$. The calculated rapidity spectra of $Ξ$ hyperons are significantly shifted to forward rapidities with respect to the spectra of $S=-1$ hyperons. We argue that this shift should be a sensitive test for the possible exotic mechanisms of $\bar p$-nucleus annihilation. The production of the double $Λ$-hypernuclei by $Ξ^-$ interaction with a secondary ta…
We study meson-baryon scattering with strangeness -1 in unitary chiral perturbation theory. Ten coupled channels are considered in our work, namely $π^0 Λ$, $π^0 Σ^0$, $π^- Σ^+$, $π^+ Σ^-$, $K^- p$, $\bar{K}^0 n$, $ηΛ$, $ηΣ^0$, $K^0 Ξ^0$ and $K^+ Ξ^-$. A large amount of experimental data are analyzed, including the recent precise measurement by the SIDDHARTA Collaboration of the energy shift and width of the $1s$ state of kaonic hydrogen. This leads to a strong constraint on the free parameters in our theory and of the resulting meson-baryon scattering amplitudes. We also analyze the uncertain…
Inspired by the newly observed $P_{ψs}^Λ(4338)$ and the reported $P_{cs}(4459)$, we indicate the existence of the molecular-type characteristic mass spectrum for hidden-charm pentaquark with strangeness. It shows that the $P_{cs}(4459)$ may contain two substructures corresponding to the $Ξ_c\bar{D}^*$ molecular states with $J^P=1/2^-$ and $3/2^-$, while there exists the corresponding $Ξ_c \bar{D}$ molecular state with $J^P=1/2^-$. As the prediction, we present another characteristic mass spectrum of the $Ξ_c^\prime\bar{D}^{(*)}$ molecular states. Experimental confirmation of these characterist…
Inspired by the observation of the $P_{cs}(4459)$ and $P_{ψs}^Λ(4338)$, we systematically investigate the magnetic moments, the transition magnetic moments, and the radiative decay behaviors of the $S$-wave isoscalar $Ξ_c^{(\prime)}\bar D^{(*)}$ molecular pentaquark states in this work. Our quantitative investigation shows that their electromagnetic properties can provide important hint to decode the inner structure of these discussed isoscalar $Ξ_c^{(\prime)}\bar D^{*}$ molecular pentaquarks. As the potential research issue, we suggest future experiment to focus on the electromagnetic propert…
We describe a calculation of the spectrum of strange and nonstrange hadrons that simultaneously correlates the dressed-quark-core masses of meson and baryon ground- and excited-states within a single framework. The foundation for this analysis is a symmetry-preserving Dyson-Schwinger equation treatment of a vector-vector contact interaction. Our results exemplify and highlight the deep impact of dynamical chiral symmetry breaking on the hadron spectrum: an accurate description of the meson spectrum entails a similarly successful prediction of the spectrum of baryons, including those with stran…
We study the strangeness $S=-2$ baryon-baryon interactions in relativistic chiral effective field theory at leading order. Among the 15 relevant low energy constants, eight of them are determined by fitting to the state of the art lattice QCD data of the HAL QCD Collaboration (with $m_π=146$ MeV), and the rest are either taken from the study of the $S=-1$ hyperon-nucleon systems, assuming strict SU(3) flavor symmetry, or temporarily set equal to zero. Using the so-obtained low energy constants, we extrapolate the results to the physical point, and show that they are consistent with the availab…
We proposed a unified framework to describe the interactions of the observed $T_{cc}$, $P_c$, and $P_{cs}$ within a quark level interaction in our previous work. In this work, we generalize our framework to the loosely bound hadronic molecules composed of heavy flavor di-hadrons with strangeness. We predict the possible $D^{(*)}D^{(*)}_s$ molecular states in the SU(3) limit with the masses of the $P_c$ states as the inputs. We also investigate the baryon-meson and baryon-baryon systems and consider the SU(3) breaking effect in their flavor wave functions. We generalize our isospin criterion of…
Strangeness is the key: from $\bar{K}N$ to $\bar{D}_s D K$
Beihang University（北京航空航天大学）；Peng Huanwu Collaborative Center for Research and Education, Beihang University（北京航空航天大学彭桓武研究中心）；Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences（中国科学院现代物理研究所南方核科学理论中心）；Frontiers Science Center for Rare Isotopes, Lanzhou University（兰州大学稀有同位素前沿科学中心）；School of Nuclear Science and Technology, Lanzhou University（兰州大学核科学与技术学院）；Department of Physics, Graduate School of Science, The University of Tokyo（东京大学理学研究科物理学系）
We explore the interactions of two strangeness -3 baryons in multiple spin channels with lattice QCD. This system provides an ideal laboratory for exploring the interactions of multi-baryon systems with minimal dependence on light quark masses. Model calculations of the two-$Ω^-$ system in two previous works have obtained conflicting results, which can be resolved by lattice QCD. The lattice calculations are performed using two different volumes with $L\sim2.5$ and 3.9 fm on anisotropic clover lattices at $m_π\sim 390$ MeV with a lattice spacing of $a_s \sim 0.123$ fm in the spatial direction …
