Search

The vanishing of the Higgs quartic coupling at a high energy scale may be explained by Intermediate Scale Supersymmetry, where supersymmetry breaks at (109-1012) GeV. The possible range of supersymmetry breaking scales can be narrowed down by precise measurements of the top quark mass and the strong coupling constant. On the other hand, nuclear recoil experiments can probe Higgsino or sneutrino dark matter up to a mass of 1012 GeV. We derive the correlation between the dark matter mass and precision measurements of standard model parameters, including supersymmetric threshold corrections. The dark matter mass is bounded from above as a function of the top quark mass and the strong coupling constant. The top quark mass and the strong coupling constant are bounded from above and below respectively for a given dark matter mass. We also discuss how the observed dark matter abundance can be explained by freeze-out or freeze-in during a matter-dominated era after inflation, with the inflaton condensate being dissipated by thermal effects.

The vanishing of the Higgs quartic coupling of the Standard Model at high energies may be explained by spontaneous breaking of Higgs Parity. Taking Higgs Parity to originate from the Left-Right symmetry of the SO(10) gauge group, leads to a new scheme for precision gauge coupling unification that is consistent with proton decay. We compute the relevant running of couplings and threshold corrections to allow a precise correlation among Standard Model parameters. The scheme has a built-in solution for obtaining a realistic value for mb/mτ , which further improves the precision from gauge coupling unification, allowing the QCD coupling constant to be predicted to the level of 1% or, alternatively, the top quark mass to 0.2%. Future measurements of these parameters may significantly constrain the detailed structure of the theory. We also study an SO(10) embedding of quark and lepton masses, showing how large neutrino mixing is compatible with small quark mixing, and predict a normal neutrino mass hierarchy. The strong CP problem may be explained by combining Higgs Parity with space-time parity.

Abstract We consider the possibility that the neutral-current B anomalies are due to radiative corrections generated by Yukawa interactions of quarks and leptons with new vector-like quark and lepton electroweak doublets and new Standard Model singlet scalars. We show that the restricted interactions needed can result from an underlying Abelian family symmetry and that the same symmetry can give rise to an acceptable pattern of quark and charged lepton masses and mixings, providing a bridge between the non-universality observed in the B-sector and that of the fermion mass matrices. We construct two simple models, one with a single singlet scalar in which the flavour changing comes from quark and lepton mixing and one with an additional scalar in which the flavour changing can come from both fermion and scalar mixing. We show that for the case the new quarks are much heavier than the new leptons and scalars the B anomalies can be due to box diagrams with couplings in the perturbative regime consistent with the bounds coming from $$ {B}_s-{\overline{B}}_s $$ B s − B ¯ s , $$ K-\overline{K} $$ K − K ¯ and $$ D-\overline{D} $$ D − D ¯ mixing as well as other lepton family number violating processes. The new states can be dark matter candidates and, in the two scalar model with a light scalar of O(60) GeV and vector-like lepton of O(100) GeV, there can be a simultaneous explanation of the B-anomalies, the muon anomalous magnetic moment and the dark matter abundance.

Low energy observables involving the Standard Model fermions which arechirality-violating, such as anomalous electromagnetic moments, necessarilyinvolve an insertion of the Higgs in order to maintain $SU(2) \times U(1)$gauge invariance. As the result, the properties of the Higgs boson measured atthe LHC impact our understanding of the associated low-energy quantities. Weillustrate this feature with a discussion of the electromagnetic moments of the$\tau$-lepton, as probed by the rare decay $H \rightarrow \tau^+ \tau^-\gamma$. We assess the feasibility of measuring this decay at the LHC, and showthat the current bounds from lower energy measurements imply that $13~\rm{TeV}$running is very likely to improve our understanding of new physics contributingto the anomalous magnetic moment of the tau.

Low energy observables involving the Standard Model fermions which are chirality-violating, such as anomalous electromagnetic moments, necessarily involve an insertion of the Higgs in order to maintain SU(2) × U(1) gauge invariance. As the result, the properties of the Higgs boson measured at the LHC impact our understanding of the associated low-energy quantities. We illustrate this feature with a discussion of the electromagnetic moments of the τ -lepton, as probed by the rare decay H → τ+τ−γ. We assess the feasibility of measuring this decay at the LHC, and show that the current bounds from lower energy measurements imply that 13 TeV running is very likely to improve our understanding of new physics contributing to the anomalous magnetic moment of the tau.

We explore the coupling of the strange quark to the state of mass close to 126 GeV recently observed by the ATLAS and CMS experiments at the LHC. An enhanced coupling relative to the expectations for a SM Higgs has the effect of increasing both the inclusive production cross section and the partial decay width into jets. For very large modifications, the latter dominates and the net rate into non-jet decay modes such as diphotons is suppressed, with the result that one can use observations of the diphoton decay mode to place an upper limit on the strange quark coupling. We find that the current observations of the diphoton decay mode imply that the coupling of the new resonance to strange quarks can be at most ∼ 50 times the SM expectation at the 95% C.L., if one assumes at most a O(1) modification of the coupling to gluons. © 2013 SISSA.