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arXiv 2104.07680hep-phhep-exnucl-exnucl-th
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轻子Z'玻色子的整体分析

Global Analysis of Leptophilic Z' Bosons

Andrzej J. Buras, Andreas Crivellin, Fiona Kirk, Claudio Andrea Manzari, Marc Montull

摘要:

新的中性重规范玻色子($Z^\prime$)在标准模型的许多扩展中被预言。当它们与夸克耦合时,LHC的边界非常严格,而亲轻子$Z^\prime$玻色子(即使有相当大的耦合)可以轻得多,因此在精确的可观测量(如$(g-2)_μ$)中导致有趣的量子效应,并产生带电轻子的味道破坏衰变。特别是,$\ell\to\ell^\primeν\barν$衰变、带电轻子的反常磁矩、$\ell\to\ell^\primeγ$和$\ell\to3\ell^\prime$衰变对亲轻子$Z^\prime$玻色子施加了严格的限制。此外,在将$Z^\prime$与SM $Z$混合的情况下,$Z$极点可观测量受到影响。鉴于这些许多可观的,我们执行一个全球性的适合亲轻子$Z^\prime$模型的主要目标是找到$Z^\prime$耦合到轻子的界限。为此,我们考虑这些耦合的一些场景。虽然在一般的情况下,相关性是弱的,但一旦对耦合施加额外的约束,这种情况就会改变。特别地,如果考虑仅由左手旋转破缺的$L_μ-L_τ$对称,或者仅考虑$τ-μ$耦合的情况。在后一种情况下,我们可以解释$(g-2)_μ$反常和$τ\toμν\barν/τ\to eν\barν$中轻子味普适性破坏的暗示,而不违反电弱精密观测量的界限。

英文摘要:

New neutral heavy gauge bosons ($Z^\prime$) are predicted within many extensions of the Standard Model. While in case they couple to quarks the LHC bounds are very stringent, leptophilic $Z^\prime$ bosons (even with sizable couplings) can be much lighter and therefore lead to interesting quantum effects in precision observables (like $(g-2)_μ$) and generate flavour violating decays of charged leptons. In particular, $\ell\to\ell^\primeν\barν$ decays, anomalous magnetic moments of charged leptons, $\ell\to\ell^\primeγ$ and $\ell\to3\ell^\prime$ decays place stringent limits on leptophilic $Z^\prime$ bosons. Furthermore, in case of mixing $Z^\prime$ with the SM $Z$, $Z$ pole observables are affected. In light of these many observables we perform a global fit to leptophilic $Z^\prime$ models with the main goal of finding the bounds for the $Z^\prime$ couplings to leptons. To this end we consider a number of scenarios for these couplings. While in generic scenarios correlations are weak, this changes once additional constraints on the couplings are imposed. In particular, if one considers an $L_μ-L_τ$ symmetry broken only by left-handed rotations, or considers the case of $τ-μ$ couplings only. In the latter setup, on can explain the $(g-2)_μ$ anomaly and the hint for lepton flavour universality violation in $τ\toμν\barν/τ\to eν\barν$ without violating bounds from electroweak precision observables.

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。

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