B-anomalies from flavorful U(1)$$'$$ extensions, safely

Abstract$$U(1)^\prime $$ U ( 1 ) ′ extensions of the standard model with generation-dependent couplings to quarks and leptons are investigated as an explanation of anomalies in rare B-decays, with an emphasis on stability and predictivity up to the Planck scale. To these ends, we introduce three generations of vector-like standard model singlet fermions, an enlarged, flavorful scalar sector, and, possibly, right-handed neutrinos, all suitably charged under the $$U(1)^\prime $$ U ( 1 ) ′ gauge interaction. We identify several gauge-anomaly free benchmarks consistent with $$B_s$$ B s -mixing constraints, with hints for electron-muon universality violation, and the global $$b \rightarrow s$$ b → s fit. We further investigate the complete two-loop running of gauge, Yukawa and quartic couplings up to the Planck scale to constrain low-energy parameters and enhance the predictive power. A characteristic of models is that the $$Z^\prime $$ Z ′ with TeV-ish mass predominantly decays to invisibles, i.e. new fermions or neutrinos. $$Z^\prime $$ Z ′ -production can be studied at a future muon collider. While benchmarks feature predominantly left-handed couplings $$C_9^{\mu }$$ C 9 μ and $$C_{10}^{\mu }$$ C 10 μ , right-handed ones can be accommodated as well.

Dark photon search at a circular e+e− collider

One of the interesting portals linking a dark sector and the Standard Model (SM) is the kinetic mixing between the SM [Formula: see text] field with a new dark photon [Formula: see text] from a [Formula: see text] gauge interaction. Stringent limits have been obtained for the kinetic mixing parameter [Formula: see text] through various processes. In this work, we study the possibility of searching for a dark photon interaction at a circular [Formula: see text] collider through the process [Formula: see text]. We find that the constraint on [Formula: see text] for dark photon mass in the few tens of GeV range, assuming that the [Formula: see text] invariant mass can be measured to an accuracy of 0.5% [Formula: see text], can be better than [Formula: see text] for the proposed CEPC with a 10-year running at [Formula: see text] (statistic) level, and better than [Formula: see text] for FCC-ee with even just one-year running at [Formula: see text], better than the LHCb, ATLAS, CMS experiments and other facilities can do in a similar dark photon mass range. For FCC-ee, running at [Formula: see text], the constraint can be even better.

Consistent gauge interaction involving dynamical coupling and anomalous current

We show a possible way to construct a consistent formalism where the effective electric charge can change with space and time without destroying the gauge invariance. In the previous work[Formula: see text] we took the gauge coupling to be of the form [Formula: see text] where [Formula: see text] is an auxiliary field, [Formula: see text] is a scalar field and the current [Formula: see text] is the Dirac current. This term produces a constraint [Formula: see text] which can be related to MIT bag model by boundary condition. In this paper, we show that when we use the term [Formula: see text], instead of the auxiliary field [Formula: see text], there is a possibility to produce a theory with dynamical coupling constant, which does not produce any constraint or confinement. The coupling [Formula: see text] where [Formula: see text] is an anomalous current is also discussed.