Muong−2anomaly and dark leptonic gauge boson

Abstract

One of the major motivations to search for a dark gauge boson of MeV -GeV scale is the longstanding gµ − 2 anomaly. Because of active searches such as fixed target experiments and rare meson decays, the gµ − 2 favored parameter region has been rapidly reduced. With the most recent data, it is practically excluded now in the popular dark photon model. We overview the issue and investigate a potentially alternative model based on the gauged lepton number or U (1)L. The gµ − 2 favored parameter region of the U (1)L survives all the constraints that were critical in the dark photon case, yet it is disfavored by the new constraints from the large flux neutrino experiments.

Lepton flavor violating Z′ explanation of the muon anomalous magnetic moment

“…With this motivation, we discuss here a simple Z interpretation of the (g − 2) µ anomaly. A sufficiently muonphilic Z can address the (g − 2) µ discrepancy [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]; however, in order to avoid stringent bounds from the charged lepton sector, while being consistent with a sizable contribution to (g − 2) µ , the Z coupling must violate lepton universality. 1 For in- 1 There are other experimental hints of lepton flavor violation or the breakdown of lepton flavor universality in processes involving muons and taus, e.g.…”

The KLOE-2 experiment at DAFNE

“…2 (top left) and Ref. [6]). M U plane for the associated production with the µ + µ − , e + e − and π + π − , and φ → ηU with Dalitz U decay (Fig.…”

“…In particular, TFFs play an important role in the determination of the light-by-light contribution to the anomalous magnetic moment of the muon [6,35]. The interest is reinforced by failure to describe the data on ω → π 0 µ + µ − decay by the Vector Meson Dominance model [36,37].…”

SIMP dark matter with gauged Z 3 symmetry

“…The parameter space of dark photon can be constrained by direct searches at colliders [29][30][31][32][33][34][35] and lepton g − 2 experiments [36,37], etc. There has been a recent study on the limits on light dark matter in the context of a vector messenger [35].…”