Showing papers on "Strangeness published in 2022"
TL;DR: In this paper, the authors explore the parameter space of hyperonic stars within the framework of the Relativistic Mean Field model allowed by the present uncertainties in the state-of-the-art nuclear and hypernuclear experimental data.
Abstract: The appearance of strangeness in the form of hyperons within the inner core of neutron stars is expected to affect its detectable properties, such as its global structure or gravitational wave emission. This work explores the parameter space of hyperonic stars within the framework of the Relativistic Mean Field model allowed by the present uncertainties in the state-of-the-art nuclear and hypernuclear experimental data. We impose multi-physics constraints at different density regimes to restrict the parameter space: Chiral effective field theory, heavy-ion collision data, and multi-messenger astrophysical observations of neutron stars. We investigate possible correlations between empirical nuclear and hypernuclear parameters, particularly the symmetry energy and its slope, with observable properties of neutron stars. We do not find a correlation for the hyperon parameters and the astrophysical data. However, the inclusion of hyperons generates a tension between the astrophysical and heavy-ion data constraining considerably the available parameter space.
24 citations
TL;DR: In this article , the authors reported precision measurements of hypernuclei lifetimes obtained from Au+Au collisions at 3.0 GeV and 7.2 GeV collected by the STAR experiment at the Relativistic Heavy Ion Collider.
Abstract: We report precision measurements of hypernuclei _{Λ}^{3}H and _{Λ}^{4}H lifetimes obtained from Au+Au collisions at sqrt[s_{NN}]=3.0 GeV and 7.2 GeV collected by the STAR experiment at the Relativistic Heavy Ion Collider, and the first measurement of _{Λ}^{3}H and _{Λ}^{4}H midrapidity yields in Au+Au collisions at sqrt[s_{NN}]=3.0 GeV. _{Λ}^{3}H and _{Λ}^{4}H, being the two simplest bound states composed of hyperons and nucleons, are cornerstones in the field of hypernuclear physics. Their lifetimes are measured to be 221±15(stat)±19(syst) ps for _{Λ}^{3}H and 218±6(stat)±13(syst) ps for _{Λ}^{4}H. The p_{T}-integrated yields of _{Λ}^{3}H and _{Λ}^{4}H are presented in different centrality and rapidity intervals. It is observed that the shape of the rapidity distribution of _{Λ}^{4}H is different for 0%-10% and 10%-50% centrality collisions. Thermal model calculations, using the canonical ensemble for strangeness, describes the _{Λ}^{3}H yield well, while underestimating the _{Λ}^{4}H yield. Transport models, combining baryonic mean-field and coalescence (jam) or utilizing dynamical cluster formation via baryonic interactions (phqmd) for light nuclei and hypernuclei production, approximately describe the measured _{Λ}^{3}H and _{Λ}^{4}H yields. Our measurements provide means to precisely assess our understanding of the fundamental baryonic interactions with strange quarks, which can impact our understanding of more complicated systems involving hyperons, such as the interior of neutron stars or exotic hypernuclei.
17 citations
TL;DR: In this paper , the first multi-differential measurements of strange hadrons of $K^{-}, $K^+K^-$ yields as well as the ratios of $\phi/K^$ and $Xi^-$ in Au+Au collisions with the STAR experiment at RHIC were reported.
10 citations
TL;DR: In this paper , the existence of the molecular-type characteristic mass spectrum for hidden-charm pentaquark with strangeness has been shown, which is a crucial step of constructing hadronic molecular family.
9 citations
28 Jan 2022
TL;DR: In this article , the meson-baryon-anti-charmed meson interactions were studied in a coupled channel analysis with a one-boson exchange model, and the potentials for the interactions were related to those in the π-c^{(*)}-bar{D}-binar systems by using the SU(3) flavor symmetry and heavy quark symmetry.
Abstract: Stimulated by the meson-baryon molecular interpretations of the $P_c$ states ($P_c(4312)/P_c(4440)/P_c(4457)$), we systematically study the interactions between an $S-$wave charm-strange baryon $\Xi_c^{(\prime,*)}$ and an anti-charmed meson $\bar{D}^{(*)}$ in a coupled channel analysis. Effective potentials for the $\Xi_c^{(\prime,*)}\bar{D}^{(*)}$ interactions in a one-boson-exchange model can be related to those in the $\Sigma_c^{(*)}\bar{D}^{(*)}$ systems by using the $SU(3)$ flavor symmetry and heavy quark symmetry. Our results can predict several promising hidden-charm molecular pentaquarks with strangeness $|S|=1$, which include the $\Xi_c^{\prime}\bar{D}$ states with $I(J^P)=0,1(1/2^-)$, the $\Xi_c^*\bar{D}$ states with $0,1(3/2^-)$, the $\Xi_c^{\prime}\bar{D}^*$ states with $0(1/2^-)$ and $0,1(3/2^-)$, and the $\Xi_c^*\bar{D}^*$ states with $0(1/2^-,3/2^-,5/2^-)$.
9 citations
TL;DR: In this paper , a unified framework was proposed to describe the interactions of the observed hadronic molecules composed of heavy flavor dihadrons with strangeness within a quark level interaction in their previous work.
Abstract: We propose 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 dihadrons 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 the formation of heavy flavor dihadron molecules to the $U/V$ spin case. For a specific heavy flavor meson-meson, baryon-meson, or baryon-baryon system, the interactions for the states with the same flavor and spin matrix elements can be related by a generalized flavor-spin symmetry.
8 citations
TL;DR: In this article , the existence of the molecular-type characteristic mass spectrum for hidden-charm pentaquark with strangeness has been shown, which is a crucial step of constructing hadronic molecular family.
8 citations
TL;DR: In this article , an attempt has been made to explore properties of $\Omega$ with hypercentral Constituent Quark Model (hCQM) with a linear confining term, the resonance mass spectra has been obtained for 1S-4S, 1P-4P, 1D-3D and 1F-2F respectively.
Abstract: $\Omega^{-}$ baryon with sss quarks has been scarcely observed in the experiments so far and has been exploited through many theoretical studies only. Here, an attempt has been made to explore properties of $\Omega$ with hypercentral Constituent Quark Model (hCQM) with a linear confining term. The resonance mass spectra has been obtained for 1S-4S, 1P-4P, 1D-3D and 1F-2F respectively. The Regge trajectory has been investigated for the linear nature based on calculated data alongwith the magnetic moment. The present work has been compared with various approaches and known experimental findings.
7 citations
TL;DR: In this paper , the magnetic moments, the transition magnetic moments and the radiative decay behaviors of the $S$-wave isoscalar molecular pentaquark states were systematically investigated.
Abstract: Inspired by the observation of the $P_{cs}(4459)$ and $P_{\psi s}^{\Lambda}(4338)$, we systematically investigate the magnetic moments, the transition magnetic moments, and the radiative decay behaviors of the $S$-wave isoscalar $\Xi_c^{(\prime)}\bar D^{(*)}$ 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 $\Xi_c^{(\prime)}\bar D^{*}$ molecular pentaquarks. As the potential research issue, we suggest future experiment to focus on the electromagnetic properties of these isoscalar $\Xi_c^{(\prime)}\bar D^{(*)}$ molecular pentaquarks, which are a typical hidden-charm molecular pentaquark system with single strangeness.
6 citations
TL;DR: In this paper , Taylor expansions for the pressure (zeroth-order cumulant), the net-baryon-number density, and the variance of the distribution on net baryon number fluctuations were derived from a series expansion of the pressure and compared to diagonal Pad\'e approximants.
Abstract: Using high statistics datasets generated in ($2+1$)-flavor QCD calculations at finite temperature, we present results for low-order cumulants of net-baryon-number fluctuations at nonzero values of the baryon chemical potential. We calculate Taylor expansions for the pressure (zeroth-order cumulant), the net-baryon-number density (first-order cumulant), and the variance of the distribution on net-baryon-number fluctuations (second-order cumulant). We obtain series expansions from an eighth-order expansion of the pressure and compare these to diagonal Pad\'e approximants. This allows us to estimate the range of values for the baryon chemical potential in which these expansions are reliable. We find ${\ensuremath{\mu}}_{B}/T\ensuremath{\le}2.5$, 2.0, and 1.5 for the zeroth-, first-, and second-order cumulants, respectively. We, furthermore, construct estimators for the radius of convergence of the Taylor series of the pressure. In the vicinity of the pseudocritical temperature ${T}_{pc}\ensuremath{\simeq}156.5\text{ }\text{ }\mathrm{MeV}$, we find ${\ensuremath{\mu}}_{B}/T\ensuremath{\gtrsim}2.9$ at vanishing strangeness chemical potential and somewhat larger values for strangeness neutral matter. These estimates are temperature dependent and range from ${\ensuremath{\mu}}_{B}/T\ensuremath{\gtrsim}2.2$ at $T=135\text{ }\text{ }\mathrm{MeV}$ to ${\ensuremath{\mu}}_{B}/T\ensuremath{\gtrsim}3.2$ at $T=165\text{ }\text{ }\mathrm{MeV}$. The estimated radius of convergences is the same for any higher-order cumulant.
6 citations
TL;DR: The spin-averaged generalized parton distributions (GPDs) of sea quarks in the proton at zero skewness from nonlocal covariant chiral effective theory, including one-loop contributions from intermediate states with pseudoscalar mesons and octet and decuplet baryons, were calculated in this paper .
Abstract: We calculate the spin-averaged generalized parton distributions (GPDs) of sea quarks in the proton at zero skewness from nonlocal covariant chiral effective theory, including one-loop contributions from intermediate states with pseudoscalar mesons and octet and decuplet baryons. A relativistic regulator is generated from the nonlocal Lagrangian where a gauge link is introduced to guarantee local gauge invariance, with additional diagrams from the expansion of the gauge link ensuring conservation of electric charge and strangeness. Flavor asymmetries for sea quarks at zero and finite momentum transfer, as well as strange form factors, are obtained from the calculated GPDs, and results compared with phenomenological extractions and lattice QCD.
TL;DR: In this paper , the authors focus on the developments in the last few years with physical parameters and low chemical potential which are obtained by extrapolations from zero or imaginary chemical potential.
Abstract: In recent years there has been much progress on the investigation of the QCD phase diagram with lattice QCD. This work will focus on the developments in the last few years with physical parameters and low chemical potential which are obtained by extrapolations from zero or imaginary chemical potential.
TL;DR: In this article , the authors constructed eight color singlet-singlet-type five-quark currents with distinguished isospins to study the molecular states with strangeness via the QCD sum rules, and showed that the central values of the pentaquark masses with higher (lower) isospin are slightly above (below) the thresholds of the corresponding meson-baryon pairs.
Abstract: In the paper, we construct eight color singlet–singlet-type five-quark currents with distinguished isospins to study the [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] 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 [Formula: see text] as the [Formula: see text] molecular state with the quantum numbers [Formula: see text]. The other predictions can be confronted to the experimental data in the future.
TL;DR: In this paper , the S-wave tetraquark states with different quantum numbers were studied in the framework of the improved chromomagnetic interaction model and the possible decay channels were analyzed by considering both angular momentum and -parity conservation.
Abstract: In the framework of the improved chromomagnetic interaction model, we complete a systematic study of the S-wave tetraquark states ( , and ) with different quantum numbers: , , and . The mass spectra of tetraquark states are predicted, and the possible decay channels are analyzed by considering both the angular momentum and -parity conservation. The recently observed hidden-charm tetraquark states with strangeness, such as , , and , can be well explained in our model. Additionally, according to the wave function of each tetraquark state, we find that the low-lying states of each configuration have a large overlap to the and meson basis, instead of the and meson basis. This indicates that one can search these tetraquark states in future experiments via the channel of and mesons.
TL;DR: In this article , the authors studied the near-threshold J/ψ meson production on protons and nuclei by considering incoherent direct non-resonant and two-step resonant K−p→Pcs(4459)0→J/Λ charmonium production processes.
14 Jun 2022
TL;DR: In this paper , the strangeness neutral line of the 4stout-improved staggered action with 8, 10, 12 and 16 time slices was considered and a generalization of the scheme introduced in [Phys. Rev. Lett. 126, 232001 (2021) to the case of nonzero strangeness neutrality was presented.
Abstract: We calculate a resummed equation of state with lattice QCD simulations at imaginary chemical potentials. This work presents a generalization of the scheme introduced in [Phys. Rev. Lett. 126, 232001 (2021) to the case of nonzero ${\ensuremath{\mu}}_{S}$, focusing on the line of strangeness neutrality. We present results up to ${\ensuremath{\mu}}_{B}/T\ensuremath{\le}3.5$ on the strangeness neutral line $⟨S⟩=0$ in the temperature range $130\text{ }\text{ }\mathrm{MeV}\ensuremath{\le}T\ensuremath{\le}280\text{ }\text{ }\mathrm{MeV}$. We also extrapolate the finite baryon density equation of state to small nonzero values of the strangeness-to-baryon ratio $R=⟨S⟩/⟨B⟩$. We perform a continuum extrapolation using lattice simulations of the 4stout-improved staggered action with 8, 10, 12 and 16 time slices.
TL;DR: In this article , the authors present novel rope hadronization results for strange hadron enhancement in pp, pPb, and PbPb collisions using PYTHIA/Angantyr at LHC energies.
TL;DR: In this article , the authors studied the effect of uncertainties in the chiral effective field theory (EFT) on the convergence of the solution of the many-body problem and the regulator-and calibration data dependence of the nuclear EFT Hamiltonian.
Abstract: The energy levels of light hypernuclei are experimentally accessible observables that contain valuable information about the interaction between hyperons and nucleons. In this work we study strangeness $S = -1$ systems $^{3,4}_\Lambda$H and $^{4,5}_\Lambda$He using the ab initio no-core shell model (NCSM) with realistic interactions obtained from chiral effective field theory ($\chi$EFT). In particular, we quantify the finite precision of theoretical predictions that can be attributed to nuclear physics uncertainties. We study both the convergence of the solution of the many-body problem (method uncertainty) and the regulator- and calibration data-dependence of the nuclear $\chi$EFT Hamiltonian (model uncertainty). For the former, we implement infrared correction formulas and extrapolate finite-space NCSM results to infinite model space. We then use Bayesian parameter estimation to quantify the resulting method uncertainties. For the latter, we employ a family of 42 realistic Hamiltonians and measure the standard deviation of predictions while keeping the leading-order hyperon-nucleon interaction fixed. Following this procedure we find that model uncertainties of ground-state $\Lambda$ separation energies amount to $\sim 20(100)$ keV in $^3_\Lambda$H($^4_\Lambda$H,He) and $\sim 400$ keV in $^5_\Lambda$He. Method uncertainties are comparable in magnitude for the $^4_\Lambda$H,He $1^+$ excited states and $^5_\Lambda$He, which are computed in limited model spaces, but otherwise much smaller. This knowledge of expected theoretical precision is crucial for the use of binding energies of light hypernuclei to infer the elusive hyperon-nucleon interaction.
TL;DR: In this paper , the axial-vector transition form factors of the baryon octet to the decuplet were investigated under the chiral quark-soliton model, with the effects of flavor SU(3) symmetry breaking included.
Abstract: We investigate the axial-vector transition form factors of the baryon octet to the baryon decuplet within the framework of the chiral quark-soliton model, with the effects of flavor SU(3) symmetry breaking included. We consider the rotational $1/{N}_{c}$ corrections and regard the strange current quark mass as a perturbation. We compare the present results for the $\mathrm{\ensuremath{\Delta}}\ensuremath{\rightarrow}N$ axial-vector transition with those from other models and lattice QCD. We also compute all possible axial-vector transitions from the baryon decuplet to the octet with the strangeness changed, i.e., $|\mathrm{\ensuremath{\Delta}}S|=1$. We obtain the value of the essential form factor ${C}_{5}^{A}$ for the $\mathrm{\ensuremath{\Delta}}\ensuremath{\rightarrow}N$ axial-vector transition at the zero momentum transfer (${Q}^{2}=0$). Furthermore, the present results are in good agreement with those fitted with the T2K data. We extract the value of the axial-vector mass ${M}_{A}$ compared to the data.
TL;DR: In this article , the electromagnetic form factors on doubly-strange hyperons in pair production from the positron-electron annihilation experiment are reviewed and compared to the standard model of particle physics.
Abstract: The standard model of particle physics is a well-tested theoretical framework, but there are still some issues that deserve experimental and theoretical investigation. The Ξ resonances with strangeness S=−2, the so-called doubly-strange hyperon, can provide important information to further test the standard model by studying their electromagnetic form factors, such as probing the limitation of the quark models and spotting unrevealed aspects of the QCD description of the structure of hadron resonances. In this work, we review some recent studies of the electromagnetic form factors on doubly-strange hyperons in pair production from positron–electron annihilation experiment.
TL;DR: In this article , the in-medium masses of open charm mesons and charmonia were investigated in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model.
Abstract: Abstract We investigate the in-medium masses of open charm mesons ( D ( , ), ( , ), ( , )) and charmonium states ( , , , , ) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model. In the presence of a magnetic field, the number and scalar densities of charged baryons have contributions from Landau energy levels. The mass modifications of open charm mesons result from their interactions with nucleons, hyperons, and the scalar fields (the non-strange field σ , strange field ζ , and isovector field δ ) in the presence of a magnetic field. The mass modifications of the charmonium states result from the modification of gluon condensates in a medium simulated by the variation in the dilaton field ( χ ) in the chiral effective model. The effects of finite quark masses are also incorporated in the trace of the energy-momentum tensor in quantum chromodynamics to investigate the mass shifts of charmonium states. The in-medium masses of open charm mesons and charmonia are observed to decrease with an increase in baryon density. The charged , , , and mesons have additional positive mass shifts due to Landau quantization in the presence of a magnetic field. The effects of the strangeness fraction are observed to be more dominant for mesons compared with D mesons. The mass shifts of charmonia are observed to be larger in hyperonic media compared with nuclear media when the effect of the finite quark mass term is neglected. These medium mass modifications can have observable consequences on the production of the open charm mesons and charmonia in high-energy asymmetric heavy-ion collision experiments.
TL;DR: The GlueX experiment at Jefferson Lab has been used to measure the spectrum of hadrons using photoproduction on a LH2 target in a wide variety of final states as mentioned in this paper .
Abstract: The GlueX experiment located at Jefferson Lab studies the spectrum of hadrons using photoproduction on a LH2 target in a wide variety of final states. With its detector system capable of measuring neutral and charged final state particles over almost the full solid angle, and very good particle identification capabilities, GlueX can measure many different hadrons containing strangeness. A linearly polarized photon beam allows the measurement of polarization observables, which contain information about the production mechanisms involved in generating strange particles in photoproduction. In addition, GlueX can perform precise cross-section measurements, which help to study the spectrum of strange hadrons. In this presentation, the GlueX experiment is introduced, and recent progress of its strangeness program is discussed. We present recent results on Σ0 beam asymmetries, Λ(1520) spin-density matrix elements and ongoing studies of the Λ(1405) lineshape. We also present our recent progress on measurements of ΛΛ̅ and Ξ(∗) photoproduction. Also, future prospects for strangeness measurements at GlueX are discussed.
TL;DR: In this article , the authors investigate the potential of producing states of dense quark-gluon matter (which they call fireballs) to resolve the muon puzzle as quantified with data from the Pierre Auger Observatory on the depth of the shower maximum and the number of muons at ground.
Abstract: Experimental observations of extensive air showers have revealed an excess of the muon content with respect to their theoretical simulations, which we refer to as the muon puzzle. This muon puzzle hampers a precise determination of the ultra-high-energy cosmic ray mass composition. We investigate the potential of producing states of dense quark-gluon matter (which we call fireballs) to resolve the muon puzzle as quantified with data from the Pierre Auger Observatory on the depth of the shower maximum and the number of muons at ground. Adopting a phenomenological fireball model, we find that the inelasticity enhancement associated with the formation of a plasma state is in tension with data on the electromagnetic longitudinal shower development. Instead, we restrict the fireball model to only enhance the strangeness produced in Standard Model hadronic interactions, and dub this model the strangeball model. With an analytic approach based on the Heitler-Matthews model we then find explicit sets of strangeball parameters that resolve the muon puzzle. Constraints from data on shower-to-shower fluctuations of the muon number require strangeness enhancements already at energies accessible to current-generation collider experiments. At Tevatron and LHC energies we estimate 40% of the interactions to produce strangeballs, corresponding to a 5–9% increase of the average fraction of energy retained in the hadronic cascade compared to predictions from current hadronic interaction models. A comparison with relevant measurements of the LHCf and LHCb detectors does not directly exclude this scenario, though the obtained tension with LHCb suggests a stringent test at 14 TeV.
04 Nov 2022
TL;DR: In this article , the authors discuss the ongoing search to verify the prediction experimentally and discuss the physical properties of the quark-gluon phase of hadronic matter, and the second half of the book covers hadronic material in confined and deconfined form.
Abstract: Before matter as we know it emerged, the universe was filled with the primordial state of hadronic matter called quark–gluon plasma. This hot soup of quarks and gluons is effectively an inescapable consequence of our current knowledge about the fundamental hadronic interactions: quantum chromodynamics. This book covers the ongoing search to verify the prediction experimentally and discusses the physical properties of this novel form of matter. It begins with an overview of the subject, followed by a discussion of experimental methods and results. The second half of the book covers hadronic matter in confined and deconfined form, and strangeness as a signature of the quark-gluon phase. It is ideal as an introduction for graduate students, as well as providing a valuable reference for researchers already working in this and related fields. This title, first published in 2002, has been reissued as an Open Access publication on Cambridge Core.
TL;DR: In this paper , beam-recoil transferred polarizations for the exclusive electroproduction of K+Λ and K+ Σ0 final states from an unpolarized proton target have been measured using the CLAS12 spectrometer at Jefferson Laboratory.
Abstract: Beam-recoil transferred polarizations for the exclusive electroproduction of K+Λ and K+Σ0 final states from an unpolarized proton target have been measured using the CLAS12 spectrometer at Jefferson Laboratory. The measurements at beam energies of 6.535 and 7.546 GeV span the range of four-momentum transfer Q2 from 0.3 to 4.5 GeV2 and invariant energy W from 1.6 to 2.4 GeV, while covering the full center-of-mass angular range of the K+. These new data extend the existing hyperon polarization data from CLAS in a similar kinematic range but from a significantly larger dataset. They represent an important addition to the world data, allowing for better exploration of the reaction mechanism in strangeness production processes, for further understanding of the spectrum and structure of excited nucleon states, and for improved insight into the strong interaction in the regime of nonperturbative dynamics.15 MoreReceived 7 February 2022Accepted 19 May 2022DOI:https://doi.org/10.1103/PhysRevC.105.065201©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectromagnetic interactionsPhysical SystemsHyperonsPropertiesPolarizationNuclear Physics
TL;DR: In this article , a search for a heavier partner of the recently observed state, denoted as , in the process , based on collision data collected at the center-of-mass energies of , 4.682 and 4.699 GeV with the BESIII detector is reported.
Abstract: We report a search for a heavier partner of the recently observed state, denoted as , in the process , based on collision data collected at the center-of-mass energies of , 4.682 and 4.699 GeV with the BESIII detector. The is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark. A partial-reconstruction technique is used to isolate recoil-mass spectra, which are probed for a potential contribution from ( ). We find an excess of ( ) candidates with a significance of , after considering systematic uncertainties, at a mass of . As the data set is limited in size, the upper limits are evaluated at the 90% confidence level on the product of the Born cross sections ( ) and the branching fraction ( ) of , under different assumptions of the mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies. The upper limits of are found to be at the level of pb at each energy. Larger data samples are needed to confirm the state and clarify its nature in the coming years.
TL;DR: The Strangeness S =−2 J-PARC E07 emulsion experiment published recently two new Ξ−−14N capture events, IRRAWADDY and IBUKI, identified by observing weak-decay sequences of pairs of single-Λ hypernuclei and interpreted as Ξ1s− and Ξ 1p− nuclear bound states, respectively, with binding energies BΞ−1s=6.27±0.27 MeV and Bξ−1p=1.21 MeV as mentioned in this paper .
TL;DR: In this article , a coupled-channels meson-baryon scattering amplitude where the $\Xi(1620)$ appears as a resonance was constructed to take into account the threshold effects.
Abstract: Spectroscopy of excited baryons with strangeness $S=-2$ is stimulated by recent experimental developments. Here we focus on the $\Xi(1620)$ which locates close to the $\bar{K}\Lambda$ threshold. To take into account the threshold effects, we construct the coupled-channels meson-baryon scattering amplitude where the $\Xi(1620)$ appears as a resonance. We demonstrate that the $\bar{K}\Lambda$ threshold effects distort the peak of the $\Xi(1620)$ resonance from the simple Breit-Wigner distribution.
TL;DR: In this paper , the bound states and the resonance states of the double-heavy tetraquarks with strange flavor in the chiral quark model were analyzed. And the results showed that the states with strong interactions are the most promising stable states against strong interactions.
Abstract:
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 resonance 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. Isospin violation is neglected herein. Our numerical analysis indicates that the states $cc\bar{u}\bar{s}$ with $\frac{1}{2}(1^+)$ and $bb\bar{u}\bar{s}$ with $\frac{1}{2}(1^+)$ are the most promising stable states against strong interactions. Besides, we also find several resonance states for the double-heavy strange tetraquarks with the real scaling method.Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.
TL;DR: In this article , the timelike EMFFs of the isospin triplet Σ hyperons measured at Babar, CLEO-c and BESIII experiments are reviewed.
Abstract: Electromagnetic form factors (EMFFs) are fundamental observable of baryons that intimately related to their internal structure and dynamics, where the EMFFs of hyperons provide valuable insight into the behavior of the strangeness. The EMFFs of hyperons can also help to understand those of nucleons as they are connected with the flavor SU(3) symmetry. The EMFFs of nucleons can be measured in both spacelike and timelike regions. However, it is difficult to probe the EMFFs of hyperons in spacelike region due to the unstable nature of hyperons. By means of electron-positron annihilation, the EMFFs of hyperons in timelike region is accessible via the production of hyperon-antihyperon pair. The timelike EMFFs of the isospin triplet Σ hyperons measured at Babar, CLEO-c and BESIII experiments are reviewed in this paper. Besides, the relevant theoretical discussion based on the experimental results are also presented.