Two-Body Hadronic Weak Decays of Bottomed Hadrons

The structure of light diquarks plays a crucial role in formation of exotic hadrons beyond the conventional quark model, especially with regard to the line shapes of bottomed hadron decays. We study the two-body hadronic weak decays of bottomed baryons and bottomed mesons to probe the light diquark structure and to pin down the quark–quark correlations in the diquark picture. It is found that the light diquark does not favor a compact structure. For instance, the isoscalar diquark [ud] in Λ_(b)^(0) can be easily split and rearranged to form ■via the color-suppressed transition. This provides a hint that the hidden charm pentaquark states produced in Λ_(b)^(0) decays could be the ■chadronic molecular candidates. This quantitative study resolves the apparent conflicts between the production mechanism and the molecular nature of these P_(c) states observed in experiment.

Selected topics of quantum computing for nuclear physics

Nuclear physics,whose underling theory is described by quantum gauge field coupled with matter,is fundamentally important and yet is formidably challenge for simulation with classical computers.Quantum computing provides a perhaps transformative approach for studying and understanding nuclear physics.With rapid scaling-up of quantum processors as well as advances on quantum algorithms,the digital quantum simulation approach for simulating quantum gauge fields and nuclear physics has gained lots of attention.In this review,we aim to summarize recent efforts on solving nuclear physics with quantum computers.We first discuss a formulation of nuclear physics in the language of quantum computing.In particular,we review how quantum gauge fields(both Abelian and non-Abelian)and their coupling to matter field can be mapped and studied on a quantum computer.We then introduce related quantum algorithms for solving static properties and real-time evolution for quantum systems,and show their applications for a broad range of problems in nuclear physics,including simulation of lattice gauge field,solving nucleon and nuclear structures,quantum advantage for simulating scattering in quantum field theory,non-equilibrium dynamics,and so on.Finally,a short outlook on future work is given.

Phenomenological study of the anisotropic quark matter in the two-flavor Nambu–Jona–Lasinio model

With the two-flavor Nambu–Jona–Lasinio (NJL) model, we carried out a phenomenological study on the chiral phase structure, mesonic properties, and transport properties of momentum-space anisotropic quark matter. To calculate the transport coefficients we utilized the kinetic theory in the relaxation time approximation, where the momentum anisotropy is embedded in the estimation of both the distribution function and relaxation time. It was shown that an increase in the anisotropy parameterξmay result in a catalysis of chiral symmetry breaking. The critical endpoint(CEP) is shifted to lower temperatures and larger quark chemical potentials asξincreases, and the impact of momentum anisotropy on the CEP temperature is almost the same as that on the quark chemical potential of the CEP. The meson masses and the associated decay widths also exhibit a significant ξ dependence. It was observed that the temperature behavior of the scaled shear viscosity η/T~3 and scaled electrical conductivity σ/T exhibited a similar dip structure, with the minima of both η/T~3 and σ/T shifting toward higher temperatures with increasing ξ. Furthermore,we demonstrated that the Seebeck coefficient S decreases when the temperature rises and its sign is positive, indicating that the dominant carriers for converting the temperature gradient to the electric field are up-quarks. The Seebeck coefficient S is significantly enhanced with a largeξfor a temperature below the critical temperature.

Molecular Nature of X(3872)in B^(0)→K^(0)X(3872)and B^(+)→K^(+)X(3872)Decays

We investigate the decays of B^(0)→K^(0)X(3872)and B^(+)→K^(+)X(3872)based on the picture where the X(3872)resonance is strongly coupled to the DD*+c.c.channel.In addition to the decay mechanism where the X(3872)resonance is formed from the DD*pair hadronization with the short-distance interaction,we have also considered the DD*rescattering diagrams in the long-distance scale,where D andD*are formed from c andDD*separately.Because of the difference of the mass thresholds of charged and neutralDD*channels,and the rather narrow width of the X(3872)resonance,at the X(3872)mass,the loop functions ofD^(0)D*^(0)andD^(+)D*^(-)are much different.Taking this difference into account,the ratio of B[B^(0)→K^(0)X(3872)]/B[B+→K+X(3872)]■0.5 can be naturally obtained.Based on this result,we also evaluate the decay widths of B_s^(0)→η(η′)X(3872).It is expected that future experimental measurements of these decays can be used to elucidate the nature of the X(3872)resonance.

Probing granular inhomogeneity of a particle-emitting source by imaging two-pion Bose–Einstein correlations

Using the source imaging technique in two-pion interferometry,we study the image of the hydrodynamic particle-emitting source with the HIJING initial conditions for relativistic heavy-ion collisions on an event-by-event basis.It is shown that the initial-state fluctuations may give rise to bumpy structures of the medium during hydrodynamical evolution,which affects the two-pion emission space and leads to a visible two-tiered shape in the source function imaged using the two-pion Bose–Einstein correlations.This two-tiered shape can be understood within a similar but more analytic granular source model and is found to be closely related to the introduced quantity n,which characterizes the granular inhomogeneity of the source.By fitting the imaged source function with a granular source parametrization,we extract the granular inhomogeneity of the hydrodynamic source,which is found to be sensitive to both the Gaussian smearing width of the HIJING initial condition and the centrality of the collisions.

Characterizing entanglement in non-Hermitian chaotic systems via out-of-time ordered correlators

We investigate the quantum entanglement in a non-Hermitian kicking system.In the Hermitian case,the out-of-time ordered correlators(OTOCs)exhibit the unbounded power-law increase with time.Correspondingly,the linear entropy,which is a common measurement of entanglement,rapidly increases from zero to almost unity,indicating the formation of quantum entanglement.For strong enough non-Hermitian driving,both the OTOCs and linear entropy rapidly saturate as time evolves.Interestingly,with the increase of non-Hermitian kicking strength,the long-time averaged value of both OTOCs and linear entropy has the same transition point where they exhibit the sharp decrease from a plateau,demonstrating the disentanglment.We reveal the mechanism of disentanglement with the extension of Floquet theory to non-Hermitian systems.

Jet Radius and Momentum Splitting Fraction with Dynamical Grooming in Heavy-Ion Collisions

We investigate the medium modifications of momentum splitting fraction and groomed jet radius with both dynamical grooming and soft drop algorithms in heavy-ion collisions.In the calculation,the partonic spectrum of initial hard scattering in p+p collisions is provided by the event generator PYTHIA8,and the energy loss of fast parton traversing in a hot/dense quantum-chromodynamic medium is simulated with the linear Boltzmann transport model.We predict the normalized distributions of the groomed jet radiusθ_(g)and momentum splitting fraction z_(g)with the dynamical grooming algorithm in Pb+Pb collisions at(sNN)~(1/2)=5.02 TeV,then compare these quantities in dynamical grooming at a=0.1,with that in soft drop at z_(out)=0.1 andβ=0.It is found that the normalized distribution ratios Pb+Pb/p+p with respect to z_(g)in z_(cut)=0.1,β=0 soft drop case are close to unity,those in a=0.1 dynamical grooming case show enhancement at small z_(g),and Pb+Pb/p+p with respect toθ_(g)in the dynamical grooming case demonstrate weaker modification than those in the soft drop counterparts.We further calculate the groomed jet number averaged momentum splitting fraction_(jets)and averaged groomed jet radius<θ_(g)>_(jets)in p+p and A+A for both grooming cases in three p_T~(ch jet)intervals,and find that the originally generated well balanced groomed jets will become more momentum imbalanced and jet size less narrowed due to jet quenching,and weaker medium modification of z_(g)andθ_(g)in the a=0.1 dynamical grooming case than in the soft drop counterparts.

Approach the Gell-Mann–Okubo Formula with Machine Learning

Machine learning is a novel and powerful technology and has been widely used in various science topics.We demonstrate a machine-learning-based approach built by a set of general metrics and rules inspired by physics.Taking advantages of physical constraints,such as dimension identity,symmetry and generalization,we succeed to approach the Gell-Mann-Okubo formula using a technique of symbolic regression.This approach can effectively find explicit solutions among user-defined observables,and can be extensively applied to studying exotic hadron spectrum.

Effect of momentum anisotropy on quark matter in the quark-meson model

We investigate the chiral phase structure of quark matter with spheroidal momentum-space anisotropy specified by one anisotropy parameter ξ in the 2+1 flavor quark-meson model.We find that the chiral phase diagram and the location of the critical endpoint(CEP) are significantly affected by the value of ξ.With an increase inξ,the CEP is shifted to lower temperatures and higher quark chemical potentials.In addition,the temperature of the CEP is more sensitive to the anisotropy parameter than the corresponding quark chemical potential,which is the opposite to that from the finite system volume effect.The effects of the momentum anisotropy on the thermodynamic properties and scalar(pseudoscalar) meson masses are also studied at the vanishing quark chemical potential.The numerical results reveal that an increase in ξ can hinder the restoration of chiral symmetry.We also find that shear viscosity and electrical conductivity decrease as ξ increases.However,the bulk viscosity exhibits a significant nontrivial behavior with ξ in the entire temperature domain of interest.

Exploring J/ψ Production Mechanism at the Future Electron-Ion Collider

We propose to use transverse momentum pT distribution of J/ψ production at the future Electron Ion Collider(EIC)to explore the production mechanism of heavy quarkonia in high energy collisions.We apply QCD and QED collinear factorization to the production of a cc pair at high pT,and non-relativistic QCD factorization to the hadronization of the pair to a J/ψ.We evaluate J/ψ pT-distribution at both leading and next-to-leading order in strong coupling,and show that production rates for various color-spin channels of a cc pair in electronhadron collisions are very different from that in hadron-hadron collisions,which provides a strong discriminative power to determine various transition rates for the pair to become a J/ψ.We predict that the J/ψproduced in electron-hadron collisions is likely unpolarized,and the production is an ideal probe for gluon distribution of colliding hadron(or nucleus).We find that the J/ψ production is dominated by the color-octet channel,providing an excellent probe to explore the gluon medium in large nuclei at the EIC.

Production of X_(eses)in heavy ion collisions

The yields of X_(cscs)with its two possible configurations,i.e.,the hadronic molecular state and tetraquark state,for Pb-Pb collisions at√sNN=5.02 TeV is studied.A volume effect is found from the centrality distribution of X_(cscs),which could help to distinguish the inner structure of X_(cscs).We also show the rapidity and the transverse momentum distributions of X_(cscs) production as well as its elliptic flow coefficient as a function of the transverse momentum.

Deep inelastic scattering with proton target in the presence of gluon condensation using holography

We study the deep inelastic scattering(DIS)of a proton-targeted lepton in the presence of gluon condensation using gauge/gravity duality.We use a modified AdS5background where the modification parameter c corresponds to the gluon condensation in the boundary theory.First,by examining the electromagnetic field,we establish that a non-zero c can increase field magnitude.Our aim is to obtain the acceptable value of c for this scattering.Our method is based on setting the mass of the proton as an eigenvalue of the baryonic state equations of the DIS to find the acceptable value of the parameter c on the other side of the equations.Therefore,in the second step,we calculate wave function equations for the baryonic states where the mass of the proton target requires a value contribution of c as c=0.0120 GeV4.Proceeding with the electromagnetic field and baryonic states,we derive the holographic interaction action related to the amplitude of the scattering.Finally,we compute the corresponding structure functions numerically as functions of x and q,which are Bj?rken variables and the lepton momentum transfers,respectively.Comparing the Jlab Hall C data with our theoretical calculations,our results are acceptable.

Study of transversity GPDs from pseudoscalar mesons production at EIC of China

The exclusive η and π^(0)electroproduction is studied in the handbag approach based on the generalized parton distributions(GPDs)factorization.Predictions of π^(0)and η mesons are calculated for future electron-ion collider in China(EicC)energy ranges,using obtained cross sections we extract information on the transversity GPDs contributions to these processes.

The time-reversal odd side of a jet

We re-examine the jet probes of the nucleon spin and flavor structures.We find for the first time that the time-reversal odd(T-odd)component of a jet,conventionally thought to vanish,can survive due to the non-perturbative fragmentation and hadronization effects.This additional contribution of a jet will lead to novel jet phenomena relevant for unlocking the access to several spin structures of the nucleon,which were thought to be impossible by using jets.As examples,we show how the T-odd constituent can couple to the proton transversity at the Electron Ion Collider(EIC)and can give rise to the anisotropy in the jet production in e^(+)e^(-) annihilations.We expect the T-odd contribution of the jet to have broad applications in high energy nuclear physics.

Exploring light-cone distribution amplitudes from quantum computing

Light-cone distribution amplitudes(LCDAs)are essential nonperturbative quantities for theoretical predictions of exclusive highenergy processes in quantum chromodynamics(QCD).We demonstrate the prospect of calculating LCDAs on a quantum computer by applying a recently proposed quantum algorithm,with staggered fermions,to the simulation of the LCDA in the(1+1)-dimensional Nambu-Jona-Lasinio(NJL)model on classical hardware.The agreement between the result from the classical simulation of the quantum algorithm and that from exact diagonalization justifies the proposed quantum algorithm.We find that the resulting LCDA in the NJL model exhibits features shared with the LCDAs obtained from the QCD.

Observation of e^(+)e^(-)→pppñπ-+c.c.

Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢdetector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb^(-1),the process e^(+)e^(-)→pppñπ+c.c.is observed for the first time with a statistical significance of 11.5σ.The average Born cross sections in the energy ranges of(4.160,4.380)GeV,(4.400,4.600)GeV and(4.610,4.700)GeV are measured to be(21.5±5.7±1.2)fb,(46.3±10.6±2.5)fb and(59.0±9.4±3.2)fb,respectively,where the first uncertainties are statistical and the second are systematic.The line shapes of the pñ and ppπ^(-)invariant mass spectra are consistent with phase space distributions,indicating that no hexaquark or di-baryon state is observed.

Observations of the Cabibbo-Suppressed decays Λ_(c)^(+)→nπ+π^(0),nπ^(+)π^(-)π^(+) and the Cabibbo-Favored decay Λ_(c)^(+)→nK^(-)π^(+)π^(+)

Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb-1,collected by the BESⅢdetector in the energy region between 4599.53 MeV and 4698.82 MeV,we report the first observations of the Cabibbo-suppressed decaysΛ_(c)^(+)→nπ^(+)π^(0),Λ_(c)^(+)→nπ^(+)π^(-)π^(+),and the Cabibbo-favored decayΛ_(c)^(+)→nK^(-)π^(+)π^(+)with statistical significances of 7.9σ,7.8σ,and>10σ,respectively.The branching fractions of these decays are measured to be B(Λ_(c)^(+)→nπ^(+)π^(0))=(0.64±0.09±0.02)%,B(Λ_(c)^(+)→nπ^(+)π^(-)π^(+))=(0.45±0.07±0.03)%,and B(Λ_(c)^(+)→nK^(-)π^(+)π^(+))=(1.90±0.08±0.09)%,where the first uncertainties are statistical and the second are systematic.We find that the branching fraction of the decayΛ_(c)^(+)→nπ^(+)π^(0)is about one order of magnitude higher than that ofΛ_(c)^(+)→nπ^(+).

Mesonic condensation in isospin matter under rotation

We investigate mesonic condensation in isospin matter under rotation.Using the two-flavor NJL effective model in the presence of global rotation,we demonstrate two important effects of rotation on its phase structure:a rotational suppression of the scalar-channel condensates,in particular,the pion condensation region;and a rotational enhancement of the rho condensation region with vector-channel condensate.A new phase diagram for isospin matter under rotation is mapped out on the ω−μI plane where the three distinct phases,corresponding to the σ,π,ρ-dominated regions,respectively,are separated by a second-order line at low isospin chemical potential as well as a first-order line at high rotation and are further connected at a tri-critical point.

Analyses of multi-pion Bose-Einstein correlations for granular sources with coherent pion-emission droplets

The ALICE Collaboration measured three-and four-pion Bose-Einstein correlations(BECs)for Pb-Pb collisions at the Large Hadron Collider(LHC).It is speculated that the observed significant suppression of multi-pion BECs is owing to a considerable degree of coherent pion emission in these collisions.Here,we study multi-pion BEC functions for granular sources with coherent pion-emission droplets.We find that the intercepts of the multi-pion correlation functions at the relative momenta near zero are sensitive to the number of droplets in the granular source.They decrease with the droplet number.The three-pion correlation functions for evolving granular sources with momentum-dependent partially coherent pion-emission droplets basically agree with the experimental data for Pb-Pb collisions at √SNN=2.76 TeV at the LHC.However,the model results for the four-pion correlation function are inconsistent with the experimental data.Investigations into normalized multi-pion correlation functions of granular sources suggest an interesting enhancement of the normalized four-pion correlation function in the moderate relative-momentum region.

Massless limit of transport theory for massive Fermions

We studied the m=0 limit of different components of Wigner functions for massive fermions. Comparingwith the chiral kinetic theory, we separated the vanishing and non-vanishing parts of vector and axial-vector components,up to the first order of . Then, we discussed the possible physical meaning of the vanishing and non-vanishingparts and their different behaviors at thermal equilibrium.