521 research outputs found
Minimal Asymmetric Dark Matter
In the early Universe, any particle carrying a conserved quantum number and
in chemical equilibrium with the thermal bath will unavoidably inherit a
particle-antiparticle asymmetry. A new particle of this type, if stable, would
represent a candidate for asymmetric dark matter (DM) with an asymmetry
directly related to the baryon asymmetry. We study this possibility for a
minimal DM sector constituted by just one (generic) multiplet
carrying hypercharge, assuming that at temperatures above the electroweak phase
transition an effective operator enforces chemical equilibrium between
and the Higgs boson. We argue that limits from DM direct detection searches
severely constrain this scenario, leaving as the only possibilities scalar or
fermion multiplets with hypercharge , preferentially quintuplets or
larger representations, and with a mass in the few TeV range.Comment: 9 pages, 2 figures, included t-channel scattering, added details on
charged-neutral mass splitting and indirect detection, accepted in PL
The LHC diphoton resonance from gauge symmetry
Motivated by what is possibly the first sign of new physics seen at the LHC,
the diphoton excess at GeV in ATLAS and CMS, we present a model that
provides naturally the necessary ingredients to explain the resonance. The
simplest phenomenological explanation for the diphoton excess requires a new
scalar state, , as well as additional vector-like (VL) fermions
introduced in an ad-hoc way in order to enhance its decays into a pair of
photons and/or increase its production cross-section. We show that the
requiered VL quarks and their couplings can emerge naturally from a complete
framework based on the gauge symmetry.Comment: 8 pages; 2 figures. v2: new references. v3: matches published version
in PR
Predicting charged lepton flavor violation from 3-3-1 gauge symmetry
The simplest realization of the inverse seesaw mechanism in a gauge theory offers striking flavor
correlations between rare charged lepton flavor violating decays and the
measured neutrino oscillations parameters. The predictions follow from the
gauge structure itself without the need for any flavor symmetry. Such tight
complementarity between charged lepton flavor violation and oscillations
renders the scenario strictly testable.Comment: 7 pages, 2 figures; v2: discussion extended. Matches version
published in PR
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