Existing pion+nucleus Drell-Yan and electron+pion scattering data are used to develop ensembles of modelindependent representations of the pion generalized parton distribution(GPD).Therewith,one arrives at a datadrive...Existing pion+nucleus Drell-Yan and electron+pion scattering data are used to develop ensembles of modelindependent representations of the pion generalized parton distribution(GPD).Therewith,one arrives at a datadriven prediction for the pion mass distribution form factor,θ_(2)^(π).Compared with the pion elastic electromagnetic form factor,θ_(2)^(π)is harder:the ratio of the radii derived from these two form factors is r_(π)^(θ2)/r_(π)= 0.79(3).Our datadriven predictions for the pion GPD,related form factors and distributions should serve as valuable constraints on theories of pion structure.展开更多
Modern and anticipated facilities will deliver data that promises to reveal the innermost workings of quantum chromodynamics(QCD).In order to fulfill that promise,phenomenology and theory must reach a new level,limiti...Modern and anticipated facilities will deliver data that promises to reveal the innermost workings of quantum chromodynamics(QCD).In order to fulfill that promise,phenomenology and theory must reach a new level,limiting and overcoming model-dependence,so that clean lines can be drawn to connect the data with QCD itself.Progress in that direction,made using continuum methods for the hadron bound-state problem,is sketched herein.展开更多
Using lattice configurations for quantum chromodynamics(QCD)generated with three domain-wall fermions at a physical pion mass,we obtain a parameter-free prediction of QCD’s renormalisation-group-invariant process-ind...Using lattice configurations for quantum chromodynamics(QCD)generated with three domain-wall fermions at a physical pion mass,we obtain a parameter-free prediction of QCD’s renormalisation-group-invariant process-independent effective charge,α^(k2).Owing to the dynamical breaking of scale invariance,evident in the emergence of a gluon mass-scale,m0=0.43(1)GeV,this coupling saturates at infrared momenta:α^(0)/π=0.97(4).Amongst other things:α^(k2)is almost identical to the process-dependent(PD)effective charge defined via the Bjorken sum rule;and also that PD charge which,employed in the one-loop evolution equations,delivers agreement between pion parton distribution functions computed at the hadronic scale and experiment.The diversity of unifying roles played byα^(k^2)suggests that it is a strong candidate for that object which represents the interaction strength in QCD at any given momentum scale;and its properties support a conclusion that QCD is a mathematically well-defined quantum field theory in four dimensions.展开更多
A symmetry-preserving continuum approach to the two valence-body bound-state problem is used to calculate the valence, glue and sea distributions within the pion; unifying them with, inter alia, electromagnetic pion e...A symmetry-preserving continuum approach to the two valence-body bound-state problem is used to calculate the valence, glue and sea distributions within the pion; unifying them with, inter alia, electromagnetic pion elastic and transition form factors. The analysis reveals the following momentum fractions at the scale ζ2:= 2GeV :〈xvalence〉 = 0.48（3）, 〈xglue〉 = 0.41（2）, 〈xsea〉 = 0.11（2）;and despite hardening induced by the emergent phenomenon of dynamical chiral symmetry breaking, the valence-quark distribution function, qπ（x）, exhibits the x ≈ 1 behaviour predicted by quantum chromodynamics（QCD）. After evolution to o ζ = 5.2 GeV, the prediction for qπ（x） matches that obtained using lattice-regularised QCD. This confluence should both stimulate improved analyses of existing data and aid in planning efforts to obtain new data on the pion distribution functions.展开更多
Clear windows onto emergent hadron mass(EHM)and modulations thereof by Higgs boson interactions are provided by observable measures of pion and kaon structure,many of which are accessible via generalised parton distri...Clear windows onto emergent hadron mass(EHM)and modulations thereof by Higgs boson interactions are provided by observable measures of pion and kaon structure,many of which are accessible via generalised parton distributions(GPDs).Beginning with algebraic GPD Ansätze,constrained entirely by hadron-scaleπand K valence-parton distribution functions(DFs),in whose forms both EHM and Higgs boson influences are manifest,numerous illustrations are provided.They include the properties of electromagnetic form factors,impact parameter space GPDs,gravitational form factors and associated pressure profiles,and the character and consequences of allorders evolution.The analyses predict that mass-squared gravitational form factors are stiffer than electromagnetic form factors;reveal that K pressure profiles are tighter than profiles,with both mesons sustaining near-core pressures at magnitudes similar to that expected at the core of neutron stars;deliver parameter-free predictions for and K valence,glue,and sea GPDs at the resolving scale l=2GeV;and predict that at this scale the fraction of meson mass-squared carried by glue and sea combined matches that lodged with the valence degrees-of-freedom,with a similar statement holding for mass-squared radii.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12135007 and 12233002)the Natural Science Foundation of Jiangsu Province (Grant No.BK20220122)+1 种基金Spanish Ministry of Science and Innovation (MICINN Grant No.PID2019-107844GB-C22)Junta de Andalucía (Grant No.P18-FR-5057)。
文摘Existing pion+nucleus Drell-Yan and electron+pion scattering data are used to develop ensembles of modelindependent representations of the pion generalized parton distribution(GPD).Therewith,one arrives at a datadriven prediction for the pion mass distribution form factor,θ_(2)^(π).Compared with the pion elastic electromagnetic form factor,θ_(2)^(π)is harder:the ratio of the radii derived from these two form factors is r_(π)^(θ2)/r_(π)= 0.79(3).Our datadriven predictions for the pion GPD,related form factors and distributions should serve as valuable constraints on theories of pion structure.
基金the National Natural Science Foundation of China(Grant Nos.11805024 and 11947406)Jiangsu Province Hundred Talents Plan for Professionals。
文摘Modern and anticipated facilities will deliver data that promises to reveal the innermost workings of quantum chromodynamics(QCD).In order to fulfill that promise,phenomenology and theory must reach a new level,limiting and overcoming model-dependence,so that clean lines can be drawn to connect the data with QCD itself.Progress in that direction,made using continuum methods for the hadron bound-state problem,is sketched herein.
文摘Using lattice configurations for quantum chromodynamics(QCD)generated with three domain-wall fermions at a physical pion mass,we obtain a parameter-free prediction of QCD’s renormalisation-group-invariant process-independent effective charge,α^(k2).Owing to the dynamical breaking of scale invariance,evident in the emergence of a gluon mass-scale,m0=0.43(1)GeV,this coupling saturates at infrared momenta:α^(0)/π=0.97(4).Amongst other things:α^(k2)is almost identical to the process-dependent(PD)effective charge defined via the Bjorken sum rule;and also that PD charge which,employed in the one-loop evolution equations,delivers agreement between pion parton distribution functions computed at the hadronic scale and experiment.The diversity of unifying roles played byα^(k^2)suggests that it is a strong candidate for that object which represents the interaction strength in QCD at any given momentum scale;and its properties support a conclusion that QCD is a mathematically well-defined quantum field theory in four dimensions.
基金Supported by the Chinese Government’s Thousand Talents Plan for Young ProfessionalsJiangsu Province Hundred Talents Plan for ProfessionalsForschungszentrum Jülich GmbH
文摘A symmetry-preserving continuum approach to the two valence-body bound-state problem is used to calculate the valence, glue and sea distributions within the pion; unifying them with, inter alia, electromagnetic pion elastic and transition form factors. The analysis reveals the following momentum fractions at the scale ζ2:= 2GeV :〈xvalence〉 = 0.48（3）, 〈xglue〉 = 0.41（2）, 〈xsea〉 = 0.11（2）;and despite hardening induced by the emergent phenomenon of dynamical chiral symmetry breaking, the valence-quark distribution function, qπ（x）, exhibits the x ≈ 1 behaviour predicted by quantum chromodynamics（QCD）. After evolution to o ζ = 5.2 GeV, the prediction for qπ（x） matches that obtained using lattice-regularised QCD. This confluence should both stimulate improved analyses of existing data and aid in planning efforts to obtain new data on the pion distribution functions.
基金Supported by National Natural Science Foundation of China(12135007,11805097)Jiangsu Provincial Natural Science Foundation of China(BK20180323)+2 种基金Spanish Ministry of Science and Innovation(MICINN)(PID2019-107844GB-C22)Junta de Andalucía(P18-FR-5057,UHU-1264517)University of Huelva(EPIT-2019)。
文摘Clear windows onto emergent hadron mass(EHM)and modulations thereof by Higgs boson interactions are provided by observable measures of pion and kaon structure,many of which are accessible via generalised parton distributions(GPDs).Beginning with algebraic GPD Ansätze,constrained entirely by hadron-scaleπand K valence-parton distribution functions(DFs),in whose forms both EHM and Higgs boson influences are manifest,numerous illustrations are provided.They include the properties of electromagnetic form factors,impact parameter space GPDs,gravitational form factors and associated pressure profiles,and the character and consequences of allorders evolution.The analyses predict that mass-squared gravitational form factors are stiffer than electromagnetic form factors;reveal that K pressure profiles are tighter than profiles,with both mesons sustaining near-core pressures at magnitudes similar to that expected at the core of neutron stars;deliver parameter-free predictions for and K valence,glue,and sea GPDs at the resolving scale l=2GeV;and predict that at this scale the fraction of meson mass-squared carried by glue and sea combined matches that lodged with the valence degrees-of-freedom,with a similar statement holding for mass-squared radii.
