We investigate the nature of the strong coupling constant and related physics.Through the analysis of accumulated experimental data around the world,we employ the ability of machine learning to unravel its physical la...We investigate the nature of the strong coupling constant and related physics.Through the analysis of accumulated experimental data around the world,we employ the ability of machine learning to unravel its physical laws.The result of our efforts is a formula that captures the expansive panorama of the distribution of the strong coupling constant across the entire energy range.展开更多
相对论性重离子对撞的目的之一是寻找量子色动力学(Quantum Chromodynamics,QCD)临界终点(Critical End Point,CEP),实验中测到的净质子数扰动呈现出非单调的行为,这暗示了CEP的存在。本文使用了3味PNJL(Polyakov-loop Nambu-Jona-Lasin...相对论性重离子对撞的目的之一是寻找量子色动力学(Quantum Chromodynamics,QCD)临界终点(Critical End Point,CEP),实验中测到的净质子数扰动呈现出非单调的行为,这暗示了CEP的存在。本文使用了3味PNJL(Polyakov-loop Nambu-Jona-Lasinio)模型,沿着从实验数据中拟合的化学冻结线,计算了重子数扰动累积量之比C4/C2随对撞能量的变化。结果发现,基于平衡态假设,在对撞能量7.7~200 GeV范围内,随着对撞能量的降低,C4/C2先缓慢下降后上升,这与实验数据一致。这也暗示平衡态假设可以用于探索重离子对撞后系统的演化行为,揭示了相变线跟化学冻结线的关系对观测量的影响非常重要。展开更多
Density fluctuations and correlations due to a first-order quark-gluon plasma to hadronic matter phase transition and its critical end point,if they remain present after the hadronic evolution in a heavy ion collision...Density fluctuations and correlations due to a first-order quark-gluon plasma to hadronic matter phase transition and its critical end point,if they remain present after the hadronic evolution in a heavy ion collisions,can lead to an enhanced production of light nuclei in these collisions.This would then result in a non-monotonic collision energy dependence of the yield ratio NtNp∕Nd2of proton number Np,deuteron number Nd,and triton number Nt.Measurements of this yield ratio as a function of collision energy thus provides the possibility to probe the equation of state of strong-interaction matter and its phase diagram.展开更多
Parton distribution functions(PDFs)are defining expressions of hadron structure.Exploiting the role of effective charges in quantum chromodynamics,an algebraic scheme is described which,given any hadron’s valence par...Parton distribution functions(PDFs)are defining expressions of hadron structure.Exploiting the role of effective charges in quantum chromodynamics,an algebraic scheme is described which,given any hadron’s valence parton PDFs at the hadron scale,delivers predictions for all its PDFs(unpolarized and polarized)at any higher scale.The scheme delivers results that are largely independent of both the value of the hadron scale and the pointwise form of the charge;and,inter alia,enables derivation of a model-independent identity that relates the strength of the proton’s gluon helicity PDF,ΔG_(p)ζ,to that of the analogous singlet polarized quark PDF and valence quark momentum fraction.Using available data fits and theory predictions,the identity yieldsΔG_(p)(ζC=√3 GeV)=1.48(10).It furthermore entails that the measurable quark helicity contribution to the proton spin is a_(op)^(ζC)=0.32(3),thereby reconciling contemporary experiment and theory.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12065014,12047501,12247101,and 12335001)the Natural Science Foundation of Gansu Province(Grant No.22JR5RA266)+5 种基金the West Light Foundation of Chinese Academy of Sciences(Grant No.21JR7RA201)supported by the China National Funds for Distinguished Young Scientists(Grant No.11825503)the National Key Research and Development Program of China(Grant No.2020YFA0406400)the 111 Project(Grant No.B20063)the fundamental Research Funds for the Central Universitiesthe Project for Top-Notch Innovative Talents of Gansu province。
文摘We investigate the nature of the strong coupling constant and related physics.Through the analysis of accumulated experimental data around the world,we employ the ability of machine learning to unravel its physical laws.The result of our efforts is a formula that captures the expansive panorama of the distribution of the strong coupling constant across the entire energy range.
基金supported by the U.S.Department of Energy under Award No.DE-SC0015266。
文摘Density fluctuations and correlations due to a first-order quark-gluon plasma to hadronic matter phase transition and its critical end point,if they remain present after the hadronic evolution in a heavy ion collisions,can lead to an enhanced production of light nuclei in these collisions.This would then result in a non-monotonic collision energy dependence of the yield ratio NtNp∕Nd2of proton number Np,deuteron number Nd,and triton number Nt.Measurements of this yield ratio as a function of collision energy thus provides the possibility to probe the equation of state of strong-interaction matter and its phase diagram.
基金supported by the National Natural Science Foundation of China(Grant No.12135007)Nanjing University of Posts and Telecommunications Science Foundation(Grant No.NY221100)+2 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20220122)Spanish Ministry of Science and Innovation(MICINN Grant No.PID2019-107844GBC22)Junta de Andalucía(Grant No.P18-FR-5057)。
文摘Parton distribution functions(PDFs)are defining expressions of hadron structure.Exploiting the role of effective charges in quantum chromodynamics,an algebraic scheme is described which,given any hadron’s valence parton PDFs at the hadron scale,delivers predictions for all its PDFs(unpolarized and polarized)at any higher scale.The scheme delivers results that are largely independent of both the value of the hadron scale and the pointwise form of the charge;and,inter alia,enables derivation of a model-independent identity that relates the strength of the proton’s gluon helicity PDF,ΔG_(p)ζ,to that of the analogous singlet polarized quark PDF and valence quark momentum fraction.Using available data fits and theory predictions,the identity yieldsΔG_(p)(ζC=√3 GeV)=1.48(10).It furthermore entails that the measurable quark helicity contribution to the proton spin is a_(op)^(ζC)=0.32(3),thereby reconciling contemporary experiment and theory.
