Is the (g − 2)μ anomaly a threat to lepton flavor conservation?

Pages, Julie (2023) Is the (g − 2)μ anomaly a threat to lepton flavor conservation? Il nuovo cimento C, 46 (1). pp. 1-7. ISSN 1826-9885

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Although the (g − 2)μ anomaly can be explained by New Physics (NP) involving only muons, a more general flavor structure is usually expected for NP operators in the Standard Model (SM) Effective Field Theory (SMEFT). In particular, if one wants to provide a combined explanation of several beyond the SM effects, like Lepton Flavor Universality (LFU) Violation, as indicated by the B anomalies, then a strong alignment of the NP operators in flavor space is required to satisfy the bounds from observables featuring Lepton Flavor Violation (LFV), like μ → eγ. We derived the tight bound of 10−5 on the flavor angle in the dipole operator in the charged-lepton mass basis in the SMEFT. We found that misalignment in several operators at high-scale could spoil the alignment at low-scale, through the Renormalization Group Evolution (RGE) of the SMEFT. In particular, it imposes constraints on some 4-fermions operators. We explored dynamical mechanisms as well as flavor symmetries to explain this flavor alignment, and illustrated the difficulty to reach it in an explicit NP model. If the (g − 2)μ anomaly is confirmed, the only natural explanation seems to lie in the individual lepton number conservation. If this accidental symmetry of the SM is also present in higher-order terms in the SMEFT, we are led to conclude that quark and lepton sectors behave quite differently beyond the SM. This proceeding is based on arXiv:2111.13724.

Item Type: Article
Subjects: 500 Scienze naturali e Matematica > 530 Fisica
Depositing User: Marina Spanti
Date Deposited: 03 Feb 2023 13:14
Last Modified: 03 Feb 2023 13:14

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