741 research outputs found
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 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, ~TeV, independently of the dark matter mass. We also comment on regime where
our bounds on the 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
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
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 and Global Symmetries
General considerations in general relativity and quantum mechanics are known
to potentially rule out continuous global symmetries in the context of any
consistent theory of quantum gravity. Assuming the validity of such
considerations, we derive stringent bounds from gamma-ray, X-ray, cosmic-ray,
neutrino, and CMB data on models that invoke global symmetries to stabilize the
dark matter particle. We compute up-to-date, robust model-independent limits on
the dark matter lifetime for a variety of Planck-scale suppressed
dimension-five effective operators. We then specialize our analysis and apply
our bounds to specific models including the Two-Higgs-Doublet, Left-Right,
Singlet Fermionic, Zee-Babu, 3-3-1 and Radiative See-Saw models. {Assuming that
(i) global symmetries are broken at the Planck scale, that (ii) the
non-renormalizable operators mediating dark matter decay have couplings,
that (iii) the dark matter is a singlet field, and that (iv) the dark matter
density distribution is well described by a NFW profile}, we are able to rule
out fermionic, vector, and scalar dark matter candidates across a broad mass
range (keV-TeV), including the WIMP regime.Comment: Matches Published version in Phys.Lett. B760 (2016) 807-81
Electrons and dark matter
Recent cosmic ray data, notably from the Pamela and Fermi satellites, indicate that previously unaccounted-for powerful sources in the Galaxy inject high-energy electrons and positrons. Interestingly, this new source class might be
related to new fundamental particle physics, and specifically to pair-annihilation or decay of galactic dark matter. I will discuss how this exciting scenario is constrained by Fermi gamma-ray observations, and which astrophysical source counterparts could also be responsible for the high-energy electron-positron excess. In particular, I will review the case for nearby mature pulsars, and the search for anisotropies in the electron-positron arrival directions as a diagnostic between the
pulsars and the dark matter scenarios
Lepton Flavor Violation, Neutralino Dark Matter and the Reach of the LHC
We revisit the phenomenology of the Constrained MSSM with right-handed
neutrinos (CMSSMRN). A supersymmetric seesaw mechanism, generating neutrino
masses and sizable lepton flavour violating (LFV) entries is assumed to be
operative. In this scheme, we study the complementarity between the `observable
ranges' of various paths leading to the possible discovery of low energy SUSY:
the reach of the Cern Large Hadron Collider (LHC), the quest for neutralino
dark matter signals and indirect searches through LFV processes. Within the
regions of the CMSSMRN parameter space compatible with all
cosmo-phenomenological requirements, those which are expected to be probed at
the LHC will be typically also accessible to upcoming LFV experiments.
Moreover, parameter space portions featuring a heavy SUSY particle spectrum
could be well beyond LHC reach while leaving LFV searches as the only key to
get a glimpse on SUSY.Comment: 31 pages, 12 figures, LateX; v2: one reference and one comment added;
matches with published versio
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