Consequences of chirally enhanced explanations of (g − 2)μ for h → μμ and Z → μμ

Abstract

With the long-standing tension between experiment and Standard-Model (SM) prediction in the anomalous magnetic moment of the muon aμ recently reaffirmed by the Fermilab experiment, the crucial question becomes which other observables could be sensitive to the underlying physics beyond the SM to which aμ may be pointing. While from the effective field theory (EFT) point of view no direct correlations exist, this changes in specific new physics models. In particular, in the case of explanations involving heavy new particles above the electroweak (EW) scale with chiral enhancement, which are preferred to evade exclusion limits from direct searches, correlations with other observables sensitive to EW symmetry breaking are expected. Such scenarios can be classified according to the SU(2)L representations and the hypercharges of the new particles. We match the resulting class of models with heavy new scalars and fermions onto SMEFT and study the resulting correlations with h → μμ and Z → μμ decays, where, via SU(2)L symmetry, the latter process is related to Z → νν and modified W-μ-ν couplings.

Universal scalar leptoquark action for matching

“…In this case, M 1 and M2 may be within the few-TeV range. Again, one may be able to account for radiative neutrino masses [53,54], or current anomalous events such as the muon anomalous magentic moment [39,[54][55][56] and certain B-meson decays [39,40].…”

Leptonic anomalous magnetic moments in ν SMEFT

“…[69], we consider the contributions of O Hνe to the Yukawa couplings of the charged leptons. Modifications of these Yukawa couplings are a common signature of explanations for the anomalies involving magnetic moments [70,71]. In particular, a nonzero C Hνe can induce large corrections to the lepton's Yukawa coupling y that are proportional to the sterile neutrino mass m j .…”

Leptonic g − 2 anomaly in an extended Higgs sector with vector-like leptons

“…Various attempts for simultaneous explanation of the leptonic anomalous magnetic moment anomalies have been made in the past several years [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Models with axionlike particles (ALP) [16], lepto-quarks [27,[30][31][32], vector-like leptons (VLL) [33][34][35][36][37][38][39] and super-symmetric models [28,29,[40][41][42] have been employed with varying success to explain the anomaly.…”