High-precision muon decay predictions for ALP searches

التفاصيل البيبلوغرافية
العنوان: High-precision muon decay predictions for ALP searches
المؤلفون: Banerjee, P., Coutinho, A. M., Engel, T., Gurgone, A., Signer, A., Ulrich, Y.
المصدر: SciPost Phys. 15, 021 (2023)
سنة النشر: 2022
المجموعة: High Energy Physics - Experiment
High Energy Physics - Phenomenology
مصطلحات موضوعية: High Energy Physics - Phenomenology, High Energy Physics - Experiment
الوصف: We present an improved theoretical prediction of the positron energy spectrum for the polarised Michel decay $\mu^+\to e^+ \nu_e\bar{\nu}_\mu$. In addition to the full next-to-next-to-leading order correction of order $\alpha^2$ in the electromagnetic coupling, we include logarithmically enhanced terms at even higher orders. Logarithms due to collinear emission are included at next-to-leading accuracy up to order $\alpha^4$. At the endpoint of the Michel spectrum, soft photon emission results in large logarithms that are resummed up to next-to-next-to-leading logarithmic accuracy. We apply our results in the context of the MEG II and Mu3e experiments to estimate the impact of the theory error on the branching ratio sensitivity for the lepton-flavour-violating decay $\mu^+\to e^+ X$ of a muon into an axion-like particle $X$.
Comment: 37 pages, 14 figures, published version
نوع الوثيقة: Working Paper
DOI: 10.21468/SciPostPhys.15.1.021
URL الوصول: http://arxiv.org/abs/2211.01040
رقم الأكسشن: edsarx.2211.01040
قاعدة البيانات: arXiv