PCAC and the deficit of forward muons in π+ production by neutrinos
PCAC and the deficit of forward muons in π+ production by neutrinos
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PCAC 和中微子产生 π+ 时正向 μ 子的不足
DOI：
10.1016/j.physletb.2007.10.025
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发表时间：
2006
影响因子：
4.4
通讯作者：
L. Sehgal
中科院分区：
文献类型：
--
作者：
D. Rein;L. Sehgal
K2K实验，在能量< E > ~ 1.3 GeV的中微子束中使用细粒度探测器，观察到双轨事件，可以解释为相干反应νμ+N→μ−+N+π+(N=C12)或非相干过程νμ+（p， N）→μ−+π++(p， N)，最终的核子未被观察到。数据显示，在Q2≤0.1 GeV2的区间内，向前移动的μ子有明显的缺陷，在这个区间内，预计会出现相当大的相干信号。我们试图解释这种效应，使用PCAC公式，其中包括不消失的介子质量的影响。约25%的抑制是由轴矢量和伪标量（介子交换）振幅的破坏性干涉引起的。非相干背景也减少了10-15%。结果，理论与观测之间的差异大大减小了。
The K2K experiment, using a fine-grained detector in a neutrino beam of energy 〈E〉∼1.3 GeV has observed two-track events that can be interpreted as a coherent reaction νμ+N→μ−+N+π+(N=C12) or an incoherent process νμ+(p,n)→μ−+π++(p,n), the final nucleon being unobserved. The data show a significant deficit of forward-going muons in the interval Q2≲0.1 GeV2, where a sizeable coherent signal is expected. We attempt an explanation of this effect, using a PCAC formula that includes the effect of the non-vanishing muon mass. A suppression of about 25% is caused by a destructive interference of the axial vector and pseudoscalar (pion-exchange) amplitudes. The incoherent background is also reduced by 10–15%. As a consequence the discrepancy between theory and observation is significantly reduced.