Proton knockout reactions are a widely used tool to study nuclear ground-state distributions. While the interpretation of traditional experiments in direct kinematics has to account for initial and final state interac...Proton knockout reactions are a widely used tool to study nuclear ground-state distributions. While the interpretation of traditional experiments in direct kinematics has to account for initial and final state interactions, experiments in inverse kinematics can overcome such limitations. We discuss results of an experiment at the BM@N setup at JINR using a <sup>12</sup>C beam at 48 GeV/c to study quasi-elastic scattering reactions, single proton distributions, and short-range correlated nucleon-nucleon pairs. The inverse kinematics allows for the direct measurement of the nucleon-nucleon pair center-of-mass motion and provides first experimental evidence for scale separation of such pairs. Based on these results, we will in the future study neutron-rich nuclei in inverse kinematics in the context of short-range correlations and neutron stars.展开更多
Spin alignments of vector mesons and hyperons in relativistic heavy-ion collisions have been proposed as signals of global polarization.The STAR experiment first observed the ∧ polarization.Recently,the ALICE collabo...Spin alignments of vector mesons and hyperons in relativistic heavy-ion collisions have been proposed as signals of global polarization.The STAR experiment first observed the ∧ polarization.Recently,the ALICE collaboration measured the transverse momentum {PT) and the collision centrality dependence of K*,and Φ spin alignments during Pb-Pb collisions at 1/2sNN=2.76 TeV.A large signal is observed in the low pT region of mid-central collisions for K*,while the signal is much smaller for Φ,and these have not been understood yet.Since vector mesons have different lifetimes and their decay products have different scattering cross sections,they suffer from different hadronic effects.In this paper,we study the effect of hadronic interactions on the spin alignment of K*,Φ,and p mesons in relativistic heavy-ion collisions with a multi-phase transport model.We find that hadronic scatterings lead to a deviation of the observed spin alignment matrix element p00 away from the true value for p and K*mesons(with a bigger effect on p) while the effect is negligible for the Φ meson.The effect depends on the kinematic acceptance:the observed p00 value is lower than the true value when the pseudorapidity(η) coverage is small,while there is little effect when the η coverage is large.Hence,this study provides valuable information to understand the vector meson spin alignment signals observed during the experiments.展开更多
Conceptually,radii are amongst the simplest Poincaré-invariant properties that can be associated with hadrons and light nuclei.Accurate values of these quantities are necessary so that one may judge the character...Conceptually,radii are amongst the simplest Poincaré-invariant properties that can be associated with hadrons and light nuclei.Accurate values of these quantities are necessary so that one may judge the character of putative solutions to the strong interaction problem within the Standard Model.However,limiting their ability to serve in this role,recent measurements and new analyses of older data have revealed uncertainties and imprecisions in the radii of the proton,pion,kaon,and deuteron.In the context of radius measurement using electron+hadron elastic scattering,the past decade has shown that reliable extraction requires minimisation of bias associated with practitioner-dependent choices of data fitting functions.Different answers to that challenge have been offered;and this perspective describes the statistical Schlessinger point method(SPM),in unifying applications to proton,pion,kaon,and deuteron radii.Grounded in analytic function theory,independent of assumptions about underlying dynamics,free from practitioner-induced bias,and applicable in the same form to diverse systems and observables,the SPM returns an objective expression of the information contained in any data under consideration.Its robust nature and versatility make it suitable for use in many branches of experiment and theory.展开更多
Sources of event-by-event elliptic flow fluctuations in relativistic heavy-ion collisions are investigated in a multiphase parton transport model （AMPT）. Besides the well-known initial eccentricity fluctuations, sev...Sources of event-by-event elliptic flow fluctuations in relativistic heavy-ion collisions are investigated in a multiphase parton transport model （AMPT）. Besides the well-known initial eccentricity fluctuations, several other sources of elliptic flow dynamical fluctuations are identified. One is fluctuations in initial parton configurations at a given eccentricity. Configuration fluctuations are found to be as important as eccentricity fluctuations in elliptic flow development. A second is quantum fluctuations in parton-parton interactions during system evolution. A third is fluctuations caused by hadronization and final-state hadronic scatterings. The magnitudes of these fluctuations are investigated relative to the eccentricity fluctuations and the average elliptic flow magnitude. The fluctuations from the latter two sources are found to be negative. The results may have important implications for the interpretation of elliptic flow data.展开更多
文摘Proton knockout reactions are a widely used tool to study nuclear ground-state distributions. While the interpretation of traditional experiments in direct kinematics has to account for initial and final state interactions, experiments in inverse kinematics can overcome such limitations. We discuss results of an experiment at the BM@N setup at JINR using a <sup>12</sup>C beam at 48 GeV/c to study quasi-elastic scattering reactions, single proton distributions, and short-range correlated nucleon-nucleon pairs. The inverse kinematics allows for the direct measurement of the nucleon-nucleon pair center-of-mass motion and provides first experimental evidence for scale separation of such pairs. Based on these results, we will in the future study neutron-rich nuclei in inverse kinematics in the context of short-range correlations and neutron stars.
基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34030000)the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030008)the National Natural Science Foundation of China(12025501,11890710,11890714,11775288)。
文摘Spin alignments of vector mesons and hyperons in relativistic heavy-ion collisions have been proposed as signals of global polarization.The STAR experiment first observed the ∧ polarization.Recently,the ALICE collaboration measured the transverse momentum {PT) and the collision centrality dependence of K*,and Φ spin alignments during Pb-Pb collisions at 1/2sNN=2.76 TeV.A large signal is observed in the low pT region of mid-central collisions for K*,while the signal is much smaller for Φ,and these have not been understood yet.Since vector mesons have different lifetimes and their decay products have different scattering cross sections,they suffer from different hadronic effects.In this paper,we study the effect of hadronic interactions on the spin alignment of K*,Φ,and p mesons in relativistic heavy-ion collisions with a multi-phase transport model.We find that hadronic scatterings lead to a deviation of the observed spin alignment matrix element p00 away from the true value for p and K*mesons(with a bigger effect on p) while the effect is negligible for the Φ meson.The effect depends on the kinematic acceptance:the observed p00 value is lower than the true value when the pseudorapidity(η) coverage is small,while there is little effect when the η coverage is large.Hence,this study provides valuable information to understand the vector meson spin alignment signals observed during the experiments.
基金Supported by the National Natural Science Foundation of China(12135007)Natural Science Foundation of Jiangsu Province(BK20220122)STRONG-2020"The strong interaction at the frontier of knowledge:fundamental research and applications"which received funding from the European Union's Horizon 2020 research and innovation programme(824093)。
文摘Conceptually,radii are amongst the simplest Poincaré-invariant properties that can be associated with hadrons and light nuclei.Accurate values of these quantities are necessary so that one may judge the character of putative solutions to the strong interaction problem within the Standard Model.However,limiting their ability to serve in this role,recent measurements and new analyses of older data have revealed uncertainties and imprecisions in the radii of the proton,pion,kaon,and deuteron.In the context of radius measurement using electron+hadron elastic scattering,the past decade has shown that reliable extraction requires minimisation of bias associated with practitioner-dependent choices of data fitting functions.Different answers to that challenge have been offered;and this perspective describes the statistical Schlessinger point method(SPM),in unifying applications to proton,pion,kaon,and deuteron radii.Grounded in analytic function theory,independent of assumptions about underlying dynamics,free from practitioner-induced bias,and applicable in the same form to diverse systems and observables,the SPM returns an objective expression of the information contained in any data under consideration.Its robust nature and versatility make it suitable for use in many branches of experiment and theory.
基金Supported by MOST,China,under 973 Grant 2015CB856901National Natural Science Foundation of China(11521064,11547143,11228513)+2 种基金U.S.Department of Energy(DE-FG02-88ER40412)Fundamental Research Funds for the Central Universities,South-Central University for Nationalities(CZQ15001)Excellent Doctorial Dissertation Cultivation Grant from Central China Normal University(2013YBZD18)
文摘Sources of event-by-event elliptic flow fluctuations in relativistic heavy-ion collisions are investigated in a multiphase parton transport model （AMPT）. Besides the well-known initial eccentricity fluctuations, several other sources of elliptic flow dynamical fluctuations are identified. One is fluctuations in initial parton configurations at a given eccentricity. Configuration fluctuations are found to be as important as eccentricity fluctuations in elliptic flow development. A second is quantum fluctuations in parton-parton interactions during system evolution. A third is fluctuations caused by hadronization and final-state hadronic scatterings. The magnitudes of these fluctuations are investigated relative to the eccentricity fluctuations and the average elliptic flow magnitude. The fluctuations from the latter two sources are found to be negative. The results may have important implications for the interpretation of elliptic flow data.
