7,758 research outputs found
Confluence of Constraints in Gauge Mediation: The 125 GeV Higgs Boson and Goldilocks Cosmology
Recent indications of a 125 GeV Higgs boson are challenging for
gauge-mediated supersymmetry breaking (GMSB), since radiative contributions to
the Higgs boson mass are not enhanced by significant stop mixing. This
challenge should not be considered in isolation, however, as GMSB also
generically suffers from two other problems: unsuppressed electric dipole
moments and the absence of an attractive dark matter candidate. We show that
all of these problems may be simultaneously solved by considering heavy
superpartners, without extra fields or modified cosmology. Multi-TeV sfermions
suppress the EDMs and raise the Higgs mass, and the dark matter problem is
solved by Goldilocks cosmology, in which TeV neutralinos decay to GeV
gravitinos that are simultaneously light enough to solve the flavor problem and
heavy enough to be all of dark matter. The implications for collider searches
and direct and indirect dark matter detection are sobering, but EDMs are
expected near their current bounds, and the resulting non-thermal gravitino
dark matter is necessarily warm, with testable cosmological implications.Comment: pdflatex, 15 pages, 11 figure
The Coulomb interaction and the inverse Faddeev-Popov operator in QCD
We give a proof of a local relation between the inverse Faddeev-Popov
operator and the non-Abelian Coulomb interaction between color charges
Halo Shape and Relic Density Exclusions of Sommerfeld-Enhanced Dark Matter Explanations of Cosmic Ray Excesses
Dark matter with Sommerfeld-enhanced annihilation has been proposed to
explain observed cosmic ray positron excesses in the 10 GeV to TeV energy
range. We show that the required enhancement implies thermal relic densities
that are too small to be all of dark matter. We also show that the dark matter
is sufficiently self-interacting that observations of elliptical galactic dark
matter halos exclude large Sommerfeld enhancement for light force carriers.
Resonant Sommerfeld enhancement does not modify these conclusions, and the
astrophysical boosts required to resolve these discrepancies are disfavored,
especially when significant self-interactions suppress halo substructure.Comment: 4 pages, discussion and references added, published versio
The age of information in gossip networks
We introduce models of gossip based communication networks in which each node
is simultaneously a sensor, a relay and a user of information. We model the
status of ages of information between nodes as a discrete time Markov chain. In
this setting a gossip transmission policy is a decision made at each node
regarding what type of information to relay at any given time (if any). When
transmission policies are based on random decisions, we are able to analyze the
age of information in certain illustrative structured examples either by means
of an explicit analysis, an algorithm or asymptotic approximations. Our key
contribution is presenting this class of models.Comment: 15 pages, 8 figure
Superconductivity in the presence of strong electron-phonon interactions and frustrated charge order
We study the superconductivity of strongly coupled electron-phonon systems
where the geometry of the lattice frustrates the charge order by the
sign-problem-free Quantum Monte Carlo(QMC) method. The results suggest that
with charge order frustrated, the superconductivity can benefit from strong
electron-phonon interaction in a wide range of coupling strengths.Comment: 5 pages + supplemental materials, 5 figures; comments are welcom
On subgroups in division rings of type
Let be a division ring with center . We say that is a {\em
division ring of type } if for every two elements the division
subring is a finite dimensional vector space over . In this paper
we investigate multiplicative subgroups in such a ring.Comment: 10 pages, 0 figure
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