强子复合性对π介子影响的研究

Study on the effect of finite size of hardons on pion

在重离子碰撞中,由于强子不能占据较近的时空点,因而强子的形成与类点物体不同.如果两个玻色子距离太近,它们就会无法区分,这样的玻色子认为是没有经历玻色-爱因斯坦统计的玻色子,而这种性质就定义为强子的复合性.强子的复合性对HBT关联的影响与强子的大小和源的尺寸有关.我们利用理想流体动力学去描述(2+1)维零重子密度的横向膨胀源,同时结合Bjorken关于源纵向膨胀的增强不变的假设,根据HBT干涉学,分析了对于不同尺寸的源,研究了复合性对π介子产生的影响,同时利用高斯公式对2π关联函数进行了拟合.拟合结果表明,复合性对于HBT半径和混沌参量的影响是非常小的,对于很小的演化源,复合性导致归一化参数明显减小,而且HBT半径减小,归一化参数也会减小.

In heavy-ion collisions,because hadrons cannot occupy too close space-time points,they are different from point-like objects.If the distance between two bosons is too close,they will be indistinguishable which are considered that have not experienced Bose-Einstein statistics,this property is defined as composite nature of hadrons.The influence of finite size of hardons on HBT correlation is related to the size of hadrons and source.We use ideal fluid dynamics to describe the horizontal expansion source of(2+1)dimensional zero baryon density,and combine with Byorken′s assumption of the enhancement invariance of source longitudinal expansion,We analysis the effects of composite nature for different sizes of sources on pion according to HBT interferometry.At the same time,the two-pion correlation function are fitted by Gaussian formula.The fitting results indicate that the effect of the composite nature on HBT radius and chaos parameters is very small,the normalized parameter was significantly reduced by the composite nature in small source,and decreases as HBT radii decreases.