The comprehensive measurement of leading particle A production in p-Be collisions at 19 GeV is presented. Leading A's production in the forward rapidity region compared with the non-strange leading baryons is strongly suppressed through the dN/dy distribution. The target dependence of leading production in p - A reaction is studied and compared with the analysis of p - Pb collisions. It is found that the more heavy target, the less probability of the strange quarks production with the increasing rapidity, but nearly the same at midrapidiry. However, the p/n ratio in p -Be interactions is nearly the same with that in p -Pb interactions, indicating more strong simple diquark-quark fragmentation scheme and a proton to neutron ratio of two, unlikely to the only relevant process in p - A collisions for leading baryons in rapidity acceptance. To explain a p/n ratio of unity other fragmentation schemes are included, dominating the diquark-quark fragmentation in relevant kinematics region, such as three quark fragmentation and/or gluon junction fragmentation.%利用循环迭代的混合事件方法分析19 GeV能量下质子轰击固定铍核的实验数据,给出领头奇异粒子Λ的dN/dy分布,发现在向前快度区域领头奇异粒子Λ被强烈的抑制,并与质子-铅的数据作比较,研究领头粒子Λ产生的靶依赖关系.结果发现:在中等快度区间,Λ产生的几率基本上相同;但随着快度增大,靶越重,产生奇异夸克的几率却越小.另外p-Be作用和p-Pb作用产生的p/n分布基本一致,这更进一步说明传统的双夸克-夸克碎裂机制已经不太可能是p-A碰撞中唯一合理的碎裂过程,还需要发展三夸克和胶子弦结碎裂机制.
展开▼
