Constraining the Z' Mass in 331 Models using Direct Dark Matter Detection

We investigate a so-called 331 extension of the Standard Model gauge sector which accommodates neutrino masses and where the lightest of the new neutral fermions in the theory is a viable particle dark matter candidate. In this model, processes mediated by the additional $Z^{\prime}$ gauge boson set both the dark matter relic abundance and the scattering cross section off of nuclei. We calculate with unprecedented accuracy the dark matter relic density, including the important effect of coannihilation across the heavy fermion sector, and show that indeed the candidate particle has the potential of having the observed dark matter density. We find that the recent LUX results put very stringent bounds on the mass of the extra gauge boson, $M_{Z^{\prime}} \gtrsim 2$~TeV, independently of the dark matter mass. We also comment on regime where our bounds on the $Z^{\prime}$ mass may apply to generic 331-like models, and on implications for LHC phenomenology.Comment: 11 pages, 7 figures. Accepted for publicatio

Supersymmetric contributions to weak decay correlation coefficients

We study supersymmetric contributions to correlation coefficients that characterize the spectral shape and angular distribution for polarized µ- and beta-decays. In the minimal supersymmetric standard model (MSSM), one-loop box graphs containing superpartners can give rise to non-(V-A)[direct-product](V-A) four-fermion operators in the presence of left-right or flavor mixing between sfermions. We analyze the present phenomenological constraints on such mixing and determine the range of allowed contributions to the weak decay correlation coefficients. We discuss the prospective implications for future µ- and beta-decay experiments, and argue that they may provide unique probes of left-right mixing in the first generation scalar fermion sector

Matrix Models of Noncommutative (2d+1) Lattice Gauge Theories

We investigate the problem of mapping, through the Morita equivalence, odd dimensional noncommutative lattice gauge theories onto suitable matrix models. We specialize our analysis to noncommutative three dimensional QED (NCQED) and scalar QED (NCSQED), for which we explicitly build the corresponding Matrix Model.Comment: 13 pages, LaTeX, no Figure

Dark Matter Complementarity and the Z′^\prime Portal

Z' gauge bosons arise in many particle physics models as mediators between the dark and visible sectors. We exploit dark matter complementarity and derive stringent and robust collider, direct and indirect constraints, as well as limits from the muon magnetic moment. We rule out almost the entire region of the parameter space that yields the right dark matter thermal relic abundance, using a generic parametrization of the Z'-fermion couplings normalized to the Standard Model Z-fermion couplings for dark matter masses in the 8 GeV-5 TeV range. We conclude that mediators lighter than 2.1 TeV are excluded regardless of the DM mass, and that depending on the Z'-fermion coupling strength much heavier masses are needed to reproduce the DM thermal relic abundance while avoiding existing limits.Comment: 19 Pages, 9 Figures. To appear in PR

The Effective Hooperon

We explore the possibility of explaining a gamma-ray excess in the Galactic Center, originally pointed out by Hooper, collaborators, and other groups, in an effective field theory framework. We assume that dark matter annihilation is mediated by particles heavy enough to be integrated out, and that such particles couple to all quark families. We calculate the effective coupling required to explain the annihilation signal in the Galactic Center, and compare with bounds from direct detection, collider searches, and the requirement that the dark matter particle make up the appropriate fraction of the universal energy budget. We find that only a very small set of operators can explain the gamma-ray excess while being consistent with other constraints. Specifically, for scalar dark matter the viable options are one scalar-type coupling to quarks and one interaction with gluons, while for fermionic (Dirac) dark matter the viable options are two scalar-type dimension-7 operators or a dimension-6 vector-type operator. In all cases, future searches with the Large Hadron Collider should probe the relevant operators' effective energy scale, while all viable interactions should escape direct detection experiments.Comment: 13 pages, 2 Figures. Published in Phys. Rev. D with the Title:Effective field theory approach to the Galactic Center gamma-ray exces

The Dark Z' Portal: Direct, Indirect and Collider Searches

We perform a detailed study of the dark Z' portal using a generic parametrization of the Z'-quarks couplings, both for light (8-15)GeV and heavy (130-1000)GeV dark matter scenarios. We present a comprehensive study of the collider phenomenology including jet clustering, hadronization, and detector artifacts, which allows us to derive accurate bounds from the search for new resonances in dijet events and from mono-jet events in the LHC 7TeV, LHC 8TeV, and Tevatron 1.96 TeV data. We also compute the dark matter relic abundance, the relevant scattering cross sections and pair-annihilation spectrum, and compare our results with the current PLANCK, Fermi-LAT and XENON100/LUX bounds. Lastly, we highlight the importance of complementary searches for dark matter, and outline the excluded versus still viable parameter space regions of the dark Z' portal.Comment: 29 pages, 21 figure

Augury of Darkness: The Low-Mass Dark Z' Portal

Dirac fermion dark matter models with heavy $Z^{\prime}$ mediators are subject to stringent constraints from spin-independent direct searches and from LHC bounds, cornering them to live near the $Z^{\prime}$ resonance. Such constraints can be relaxed, however, by turning off the vector coupling to Standard Model fermions, thus weakening direct detection bounds, or by resorting to light $Z^{\prime}$ masses, below the Z pole, to escape heavy resonance searches at the LHC. In this work we investigate both cases, as well as the applicability of our findings to Majorana dark matter. We derive collider bounds for light $Z^{\prime}$ gauge bosons using the $CL_S$ method, spin-dependent scattering limits, as well as the spin-independent scattering rate arising from the evolution of couplings between the energy scale of the mediator mass and the nuclear energy scale, and indirect detection limits. We show that such scenarios are still rather constrained by data, and that near resonance they could accommodate the gamma-ray GeV excess in the Galactic center.Comment: 25 pages, 6 Figures. Typos correcte