If two annihilation products of dark matter(DM)particles are non-relativistic and couple to a light force mediator,their plane wave functions are modified due to multiple exchanges of the force mediator.This gives ris...If two annihilation products of dark matter(DM)particles are non-relativistic and couple to a light force mediator,their plane wave functions are modified due to multiple exchanges of the force mediator.This gives rise to the final state Sommerfeld(FSS)effect.It is also possible that the final state particles form a bound state.Both the FSS effect and final bound-state(FBS)effect need to be considered in the calculation of the DM relic abundance.The annihilation products can be non-relativistic if their masses are comparable to those of the annihilating DM particles.We study the FSS and FBS effects in the mass-degenerate region using two specific models.Both models serve to illustrate different partial-wave contributions in the calculations of the FSS and FBS effects.We find that the FBS effect can be comparable to the FSS effect when the annihilation products couple strongly with a light force mediator.Those effects significantly modify the DM relic abundance.展开更多
本文利用BBK模型和DWBA模型计算共面非对称几何条件下中、低能电子碰撞电离H原子的三重微分截面,所得结果与实验测量进行比较,进而研究初态入射电子的扭曲效应和末态出射电子之间的关联效应对三重微分截面的影响,并对这些影响给出定性...本文利用BBK模型和DWBA模型计算共面非对称几何条件下中、低能电子碰撞电离H原子的三重微分截面,所得结果与实验测量进行比较,进而研究初态入射电子的扭曲效应和末态出射电子之间的关联效应对三重微分截面的影响,并对这些影响给出定性的物理解释.我们发现,初态扭曲效应比较微弱,在150 e V以上入射能量时可以忽略;而末态关联效应则十分重要,它会抑制Binary峰的高度,改善Recoil峰的形状,并且使Binary峰和Recoil峰都向大角度偏移,从而使理论结果更接近实验测量.展开更多
We propose one possible mechanism,i.e.,the vector meson （VV） rescattering effects,to interpret the near threshold narrow enhancement observed in J/ψ → γpp.The estimate indicates that these effects can give sizeab...We propose one possible mechanism,i.e.,the vector meson （VV） rescattering effects,to interpret the near threshold narrow enhancement observed in J/ψ → γpp.The estimate indicates that these effects can give sizeable contributions to this channel,and a destructive interference between different rescattering amplitudes is required to reproduce the line shape of the data.展开更多
The charged-particle final state spectrum is derived from an analytic perturbative solution for relativistic viscous hydrodynamics. By taking into account the longitudinal acceleration effect in relativistic viscous h...The charged-particle final state spectrum is derived from an analytic perturbative solution for relativistic viscous hydrodynamics. By taking into account the longitudinal acceleration effect in relativistic viscous hydrody namics, the pseudorapidity spectrum describes the nucleus-nucleus colliding systems at RHIC and the LHC well. Based on both the extracted longitudinal acceleration parameter λ^＊ and a phenomenological description of λ^＊, the charged-particle pseudorapidity distributions for √SNN= 5.44 TeV Xe＋Xe collisions are computed from the final state expression in a limited space-time rapidity ~/8 region.展开更多
We investigate the decay of a_1^+(1260) →π^+π^+π^-with the assumption that the a_1(1260) is dynamically generated from the coupled channel ρπ and KK~*interactions. In addition to the tree level diagrams that pro...We investigate the decay of a_1^+(1260) →π^+π^+π^-with the assumption that the a_1(1260) is dynamically generated from the coupled channel ρπ and KK~*interactions. In addition to the tree level diagrams that proceed via a_1^+(1260) →ρ~0π^+→π^+π^+π^-, we take into account also the final state interactions of ππ→ππ and KK →ππ. We calculate the invariant π^+π^-mass distribution and also the total decay width of a_1^+(1260) →π^+π^+π^-as a function of the mass of a_1(1260). The calculated total decay width of a_1(1260) is significantly different from other model calculations and tied to the dynamical nature of the a_1(1260) resonance. The future experimental observations could test of model calculations and would provide vary valuable information on the relevance of the ρπ component in the a_1(1260) wave function.展开更多
基金the One Hundred Talent Program of Sun Yat-sen University,China。
文摘If two annihilation products of dark matter(DM)particles are non-relativistic and couple to a light force mediator,their plane wave functions are modified due to multiple exchanges of the force mediator.This gives rise to the final state Sommerfeld(FSS)effect.It is also possible that the final state particles form a bound state.Both the FSS effect and final bound-state(FBS)effect need to be considered in the calculation of the DM relic abundance.The annihilation products can be non-relativistic if their masses are comparable to those of the annihilating DM particles.We study the FSS and FBS effects in the mass-degenerate region using two specific models.Both models serve to illustrate different partial-wave contributions in the calculations of the FSS and FBS effects.We find that the FBS effect can be comparable to the FSS effect when the annihilation products couple strongly with a light force mediator.Those effects significantly modify the DM relic abundance.
文摘本文利用BBK模型和DWBA模型计算共面非对称几何条件下中、低能电子碰撞电离H原子的三重微分截面,所得结果与实验测量进行比较,进而研究初态入射电子的扭曲效应和末态出射电子之间的关联效应对三重微分截面的影响,并对这些影响给出定性的物理解释.我们发现,初态扭曲效应比较微弱,在150 e V以上入射能量时可以忽略;而末态关联效应则十分重要,它会抑制Binary峰的高度,改善Recoil峰的形状,并且使Binary峰和Recoil峰都向大角度偏移,从而使理论结果更接近实验测量.
基金Supported by National Natural Science Foundation of China (10675131,10491306)Chinese Academy of Sciences (KJCX3-SYW-N2)Ministry of Science and Technology of China (2009CB825200)
文摘We propose one possible mechanism,i.e.,the vector meson （VV） rescattering effects,to interpret the near threshold narrow enhancement observed in J/ψ → γpp.The estimate indicates that these effects can give sizeable contributions to this channel,and a destructive interference between different rescattering amplitudes is required to reproduce the line shape of the data.
基金Supported by National Natural Science Foundation of China(11435004)the Chinese-Hungarian bilateral cooperation program(Te’T12CN-1-2012-0016)the CCNU PhD Fund 2016YBZZ100 of China
文摘The charged-particle final state spectrum is derived from an analytic perturbative solution for relativistic viscous hydrodynamics. By taking into account the longitudinal acceleration effect in relativistic viscous hydrody namics, the pseudorapidity spectrum describes the nucleus-nucleus colliding systems at RHIC and the LHC well. Based on both the extracted longitudinal acceleration parameter λ^＊ and a phenomenological description of λ^＊, the charged-particle pseudorapidity distributions for √SNN= 5.44 TeV Xe＋Xe collisions are computed from the final state expression in a limited space-time rapidity ~/8 region.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11475227 and 11735003supported by the Youth Innovation Promotion Association CAS(No.2016367)
文摘We investigate the decay of a_1^+(1260) →π^+π^+π^-with the assumption that the a_1(1260) is dynamically generated from the coupled channel ρπ and KK~*interactions. In addition to the tree level diagrams that proceed via a_1^+(1260) →ρ~0π^+→π^+π^+π^-, we take into account also the final state interactions of ππ→ππ and KK →ππ. We calculate the invariant π^+π^-mass distribution and also the total decay width of a_1^+(1260) →π^+π^+π^-as a function of the mass of a_1(1260). The calculated total decay width of a_1(1260) is significantly different from other model calculations and tied to the dynamical nature of the a_1(1260) resonance. The future experimental observations could test of model calculations and would provide vary valuable information on the relevance of the ρπ component in the a_1(1260) wave function.
