HARD EXCLUSIVE ELECTROPRODUCTION OF RESONANT AND NON-RESONANT PIONPAIRS AT HERMES

Fizika B (Zagreb)

ALEXANDER BORISSOV¹ 

关键词: resonant and non-resonant p+ p- pairs;    cross sections;    hard exclusiveelectroproduction;    generalized parton distributions;   

DOI  :  

学科分类：物理（综合）

来源: Fizika B: a journal of experimental and theoretical physics

【 摘 要 】

A selection of recent HERMES results is presented on the hard exclusiveelectroproduction of resonant and non-resonant p⁺ p^- pairs. The ratio of r⁰electroproduction cross sections per nucleon on ¹⁴N as compared to that on ¹H,known as the nuclear transparency, was found to increase (decrease) with increasingcoherence length for coherent (incoherent) r⁰electroproduction. For a fixed coherence length, a rise of the nuclear transparency with Q²is observed for both coherent and incoherent r⁰production, which is in agreement with theoretical calculations that include the effect ofcolor transparency. The first-order intensity density for exclusive electroproduction of p⁺ p^- pairs has beenstudied as a function of the invariant mass M_pp inthe range 0.3 < M_p⁺p^-< 1.5 GeV. The derived quantities show a dependence of the p⁺p^- invariant mass, which can be understood as due tothe interference between pion pairs in relative P-wave (isovector channel) and S,D-waves(isoscalar channel) states.

【 授权许可】

Unknown