arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1909.08571hep-ph
收藏

MiniBooNE类电子事件过剩的标准模型解释

A Standard Model explanation for the excess of electron-like events in MiniBooNE

A. Ioannisian

摘要:

本文研究了在MiniBooNE实验的4个动量转移区($Δ$共振质量区),中性流(NC)中微子诱导的$π^0$ /光子产生($ν_μ+ A \to ν_μ+1π^0 / γ+ X$)对靶核原子序数A的依赖关系.我们的结论是基于在美因茨MAMI加速器的A2合作的光子-核相互作用的实验数据。我们在不受其产生通道影响的情况下,通过光子或Z玻色子,研究了$Δ$共振的衰变。$1π^0+X$的生产按A $^{2/3}$(细胞核的表面积)进行缩放。同时,在$Δ$衰变中产生的光子将离开原子核,并且该截面将与原子核的原子序数成比例。因此,光子产生与$π^0$产生的比率与A $^{1/3}$成比例。对于碳$^{12}$ C,该因子为$\approx$ 2.3。MiniBooNE将光子产生速率标准化为测量的$π^0$产生速率。中性π介子产生率的降低将产生至少两倍于先前预期的光子,从而显著降低无法解释的类电子事件的数量。

英文摘要:

We study the dependence of neutral current (NC) neutrino-induced $π^0$/photon production ($ν_μ+ A \to ν_μ+1π^0 / γ+ X$) on the atomic number of the target nucleus, A, at 4-momentum transfers relevant to the MiniBooNE experiment: $Δ$ resonance mass region. Our conclusion is based on experimental data for photon-nucleus interactions from the A2 collaboration at the Mainz MAMI accelerator. We work in the approximation that decays of $Δ$ resonance unaffected by its production channel, via photon or Z boson. $1π^0+X$ production scales as A$^{2/3}$, the surface area of the nucleus. Meanwhile the photons created in $Δ$ decays will leave the nucleus, and that cross section will be proportional to the atomic number of the nucleus. Thus the ratio of photon production to $π^0$ production is proportional to A$^{1/3}$. For carbon $^{12}$C this factor is $\approx$2.3. MiniBooNE normalises the rate of photon production to the measured $π^0$ production rate. The reduced neutral pion production rate would yield at least twice as many photons as previously expected, thus significantly lowering the number of unexplained electron-like events.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑