原子核格点有效场论(Nuclear Lattice Effective Field Theory)是近些年发展起来的一种高精度原子核第一性原理计算方法。它将手征有效场论与格点量子蒙特卡罗方法有机结合起来,能够在统一的理论框架下构建核力与求解量子多体问题。近...原子核格点有效场论(Nuclear Lattice Effective Field Theory)是近些年发展起来的一种高精度原子核第一性原理计算方法。它将手征有效场论与格点量子蒙特卡罗方法有机结合起来,能够在统一的理论框架下构建核力与求解量子多体问题。近年来新发展出来的波函数匹配(wave function matching)方法与微扰量子蒙特卡罗方法(perturbative quantum Monte Carlo method)为解决著名的“符号问题”开辟了全新的路径。本工作在这些方法的基础上,通过计算两点关联函数发展出格点上电荷半径的微扰计算方法,验证计算表明了本工作的可靠性。使用手征N^(3)LO核力的计算能够很好地复现^(4)He、^(12)C与^(16)O的实验测量结果。展开更多
The extrapolation of nucleon axial charge gA is investigated within the framework of heavy baryon chiral effective field theory. The intermediate octet and decuplet baryons are included in the one loop calculation. Fi...The extrapolation of nucleon axial charge gA is investigated within the framework of heavy baryon chiral effective field theory. The intermediate octet and decuplet baryons are included in the one loop calculation. Finite range regularization is applied to improve the convergence in the quark-mass expansion. The lattice data from three different groups are used for the extrapolation. At physical pion mass, the extrapolated gA are all smaller than the experimental value.展开更多
Recently,we have derived a two–nucleon potential and consistent nuclear electromagnetic currents in chiral effective field theory with pions and nucleons as explicit degrees of freedom.The calculation of the currents...Recently,we have derived a two–nucleon potential and consistent nuclear electromagnetic currents in chiral effective field theory with pions and nucleons as explicit degrees of freedom.The calculation of the currents has been carried out to include N 3 LO corrections,consisting of two–pion exchange and contact contributions.The latter involve unknown low-energy constants （LECs）,some of which have been fixed by fitting the np Sand P-wave phase shifts up to 100 MeV lab energies.The remaining LECs entering the current operator are determined so as to reproduce the experimental deuteron and trinucleon magnetic moments,as well as the np cross section.This electromagnetic current operator is utilized to study the nd and n 3 He radiative captures at thermal neutron energies.Here we discuss our results stressing on the important role played by the LECs in reproducing the experimental data.展开更多
Neutron-antineutron(n−n)oscillations in the deuteron are considered.Specifically,the deuteron lifetime is calculated in terms of the free-space n−n oscillation time τn−n based on NN and NN interactions derived within...Neutron-antineutron(n−n)oscillations in the deuteron are considered.Specifically,the deuteron lifetime is calculated in terms of the free-space n−n oscillation time τn−n based on NN and NN interactions derived within chiral effective field theory(EFT).This results in(2.6±0.1)×10^22τ2^n−n s,which is close to the value obtained by Dover and collaborators more than three decades ago,but disagrees with recent EFT calculations that were performed within the perturbative scheme proposed by Kaplan,Savage,and Wise.Possible reasons for the difference are discussed.展开更多
We apply a recently proposed covariant power counting in nucleon-nucleon interactions to study strangeness S =-1 ΛN-Σ N interactions in chiral effective field theory. At leading order, Lorentz invariance introduces ...We apply a recently proposed covariant power counting in nucleon-nucleon interactions to study strangeness S =-1 ΛN-Σ N interactions in chiral effective field theory. At leading order, Lorentz invariance introduces 12 low energy constants, in contrast to the heavy baryon approach, where only five appear. The Kadyshevsky equation is adopted to resum the potential in order to account for the non-perturbative nature of hyperon-nucleon interactions.A fit to the 36 hyperon-nucleon scattering data points yields χ2 16, which is comparable with the sophisticated phenomenological models and the next-to-leading order heavy baryon approach. However, one cannot achieve a simultaneous description of the nucleon-nucleon phase shifts and strangeness S =-1 hyperon-nucleon scattering data at leading order.展开更多
文摘原子核格点有效场论(Nuclear Lattice Effective Field Theory)是近些年发展起来的一种高精度原子核第一性原理计算方法。它将手征有效场论与格点量子蒙特卡罗方法有机结合起来,能够在统一的理论框架下构建核力与求解量子多体问题。近年来新发展出来的波函数匹配(wave function matching)方法与微扰量子蒙特卡罗方法(perturbative quantum Monte Carlo method)为解决著名的“符号问题”开辟了全新的路径。本工作在这些方法的基础上,通过计算两点关联函数发展出格点上电荷半径的微扰计算方法,验证计算表明了本工作的可靠性。使用手征N^(3)LO核力的计算能够很好地复现^(4)He、^(12)C与^(16)O的实验测量结果。
基金Supported by National Natural Science Foundation of China(11475186)Sino-German CRC 110(NSFC 11621131001)
文摘The extrapolation of nucleon axial charge gA is investigated within the framework of heavy baryon chiral effective field theory. The intermediate octet and decuplet baryons are included in the one loop calculation. Finite range regularization is applied to improve the convergence in the quark-mass expansion. The lattice data from three different groups are used for the extrapolation. At physical pion mass, the extrapolated gA are all smaller than the experimental value.
基金supported by the U.S.Department of Energy,Office of Nuclear Physics,under contracts DE-AC05-06OR23177
文摘Recently,we have derived a two–nucleon potential and consistent nuclear electromagnetic currents in chiral effective field theory with pions and nucleons as explicit degrees of freedom.The calculation of the currents has been carried out to include N 3 LO corrections,consisting of two–pion exchange and contact contributions.The latter involve unknown low-energy constants （LECs）,some of which have been fixed by fitting the np Sand P-wave phase shifts up to 100 MeV lab energies.The remaining LECs entering the current operator are determined so as to reproduce the experimental deuteron and trinucleon magnetic moments,as well as the np cross section.This electromagnetic current operator is utilized to study the nd and n 3 He radiative captures at thermal neutron energies.Here we discuss our results stressing on the important role played by the LECs in reproducing the experimental data.
基金supported in part by the DFG and the NSFC through funds provided to the Sino-German CRC 110"Symmetries and the Emergence of Structure in QCD"(DFG grant.no.TRR 110)the VolkswagenStiftung(93562)supported in part by The Chinese Academy of Sciences(CAS)President’s International Fellowship Initiative(PIFI)(2018DM0034)
文摘Neutron-antineutron(n−n)oscillations in the deuteron are considered.Specifically,the deuteron lifetime is calculated in terms of the free-space n−n oscillation time τn−n based on NN and NN interactions derived within chiral effective field theory(EFT).This results in(2.6±0.1)×10^22τ2^n−n s,which is close to the value obtained by Dover and collaborators more than three decades ago,but disagrees with recent EFT calculations that were performed within the perturbative scheme proposed by Kaplan,Savage,and Wise.Possible reasons for the difference are discussed.
基金Supported by the National Natural Science Foundation of China(11375024,11522539,11375120)the China Postdoctoral Science Foundation(2016M600845,2017T100008)the Fundamental Research Funds for the Central Universities
文摘We apply a recently proposed covariant power counting in nucleon-nucleon interactions to study strangeness S =-1 ΛN-Σ N interactions in chiral effective field theory. At leading order, Lorentz invariance introduces 12 low energy constants, in contrast to the heavy baryon approach, where only five appear. The Kadyshevsky equation is adopted to resum the potential in order to account for the non-perturbative nature of hyperon-nucleon interactions.A fit to the 36 hyperon-nucleon scattering data points yields χ2 16, which is comparable with the sophisticated phenomenological models and the next-to-leading order heavy baryon approach. However, one cannot achieve a simultaneous description of the nucleon-nucleon phase shifts and strangeness S =-1 hyperon-nucleon scattering data at leading order.
