170 research outputs found
Wino Dark Matter Under Siege
A fermion triplet of SU(2)_L - a wino - is a well-motivated dark matter
candidate. This work shows that present-day wino annihilations are constrained
by indirect detection experiments, with the strongest limits coming from
H.E.S.S. and Fermi. The bounds on wino dark matter are presented as a function
of mass for two scenarios: thermal (winos constitute a subdominant component of
the dark matter for masses less than 3.1 TeV) and non-thermal (winos comprise
all the dark matter). Assuming the NFW halo model, the H.E.S.S. search for
gamma-ray lines excludes the 3.1 TeV thermal wino; the combined H.E.S.S. and
Fermi results completely exclude the non-thermal scenario. Uncertainties in the
exclusions are explored. Indirect detection may provide the only probe for
models of anomaly plus gravity mediation where the wino is the lightest
superpartner and scalars reside at the 100 TeV scale.Comment: 29 pages plus references, 9 figures, 2 appendices; v2 references
added; v3 minor changes, journal versio
Asymmetric Dark Matter from a GeV Hidden Sector
Asymmetric Dark Matter (ADM) models relate the dark matter density to the
baryon asymmetry, so that a natural mass scale for ADM is around a few GeV. In
existing models of ADM, this mass scale is unexplained; here we generate this
GeV scale for dark matter (DM) from the weak scale via gauge kinetic mixing
with a new Abelian dark force. In addition, this dark sector provides an
efficient mechanism for suppressing the symmetric abundance of DM through
annihilations to the dark photon. We augment this sector with a higher
dimensional operator responsible for communicating the baryon asymmetry to the
dark sector. Our framework also provides DM candidate for gauge mediation
models. It results in a direct detection cross section of interest for current
experiments: sigma less than or similar to 10^{-42} cm^2 for DM masses in the
range 1 - 15 GeV.Comment: 21 pages, 4 figure
MIGRATION PATTERNS AND MOVEMENTS OF SANDHILL CRANES WINTERING IN CENTRAL AND SOUTHWESTERN LOUISIANA
In this study we trapped wintering sandhill cranes (Grus canadensis) in Louisiana and fitted them with satellite transmitters to determine their migration routes. Four of the 6 sandhill cranes with validated locations and a terminus point used the Central Flyway for spring migration; 2 of these 4 (the only 2 for which we have data) also used the Central Flyway for fall migration. Two of the 6 birds used the Mississippi Flyway for spring migration. The results of this study suggest that reintroduced whooping cranes (G. americana) that intermix and migrate with sandhill cranes that winter in Louisiana may enter the Central Flyway. In addition, the Mississippi Flyway is a viable option to use as a migration route for whooping cranes if they are reintroduced in Louisiana
Disentangling Dimension Six Operators through Di-Higgs Boson Production
New physics near the TeV scale can generate dimension-six operators that
modify the production rate and branching ratios of the Higgs boson. Here, we
show how Higgs boson pair production can yield complementary information on
dimension-six operators involving the gluon field strength. For example, the
invariant mass distribution of the Higgs boson pair can show the extent to
which the masses of exotic TeV-scale quarks come from electroweak symmetry
breaking. We discuss both the current Tevatron bounds on these operators and
the most promising LHC measurement channels for two different Higgs masses: 120
GeV and 180 GeV. We argue that the operators considered in this paper are the
ones most likely to yield interesting Higgs pair physics at the LHC.Comment: 20 pages, 7 figures; v2: to match JHEP versio
DREDed Anomaly Mediation
We offer a guide to dimensional reduction (DRED) in theories with anomaly
mediated supersymmetry breaking. Evanescent operators proportional to epsilon
arise in the bare Lagrangian when it is reduced from d=4 to d= (4-2 epsilon)
dimensions. In the course of a detailed diagrammatic calculation, we show that
inclusion of these operators is crucial. The evanescent operators conspire to
drive the supersymmetry-breaking parameters along anomaly-mediation
trajectories across heavy particle thresholds, guaranteeing the ultraviolet
insensitivity.Comment: 24 pages. 10 figures. Uses Axodraw. Reference adde
CoGeNT Interpretations
Recently, the CoGeNT experiment has reported events in excess of expected
background. We analyze dark matter scenarios which can potentially explain this
signal. Under the standard case of spin independent scattering with equal
couplings to protons and neutrons, we find significant tensions with existing
constraints. Consistency with these limits is possible if a large fraction of
the putative signal events is coming from an additional source of experimental
background. In this case, dark matter recoils cannot be said to explain the
excess, but are consistent with it. We also investigate modifications to dark
matter scattering that can evade the null experiments. In particular, we
explore generalized spin independent couplings to protons and neutrons, spin
dependent couplings, momentum dependent scattering, and inelastic interactions.
We find that some of these generalizations can explain most of the CoGeNT
events without violation of other constraints. Generalized couplings with some
momentum dependence, allows further consistency with the DAMA modulation
signal, realizing a scenario where both CoGeNT and DAMA signals are coming from
dark matter. A model with dark matter interacting and annihilating into a new
light boson can realize most of the scenarios considered.Comment: 24 pages, 12 figs, v2: published version, some discussions clarifie
Data-Driven Inference of Representation Invariants
A representation invariant is a property that holds of all values of abstract
type produced by a module. Representation invariants play important roles in
software engineering and program verification. In this paper, we develop a
counterexample-driven algorithm for inferring a representation invariant that
is sufficient to imply a desired specification for a module. The key novelty is
a type-directed notion of visible inductiveness, which ensures that the
algorithm makes progress toward its goal as it alternates between weakening and
strengthening candidate invariants. The algorithm is parameterized by an
example-based synthesis engine and a verifier, and we prove that it is sound
and complete for first-order modules over finite types, assuming that the
synthesizer and verifier are as well. We implement these ideas in a tool called
Hanoi, which synthesizes representation invariants for recursive data types.
Hanoi not only handles invariants for first-order code, but higher-order code
as well. In its back end, Hanoi uses an enumerative synthesizer called Myth and
an enumerative testing tool as a verifier. Because Hanoi uses testing for
verification, it is not sound, though our empirical evaluation shows that it is
successful on the benchmarks we investigated.Comment: 18 Pages, Full version of PLDI 2020 pape
Signatures of Baryogenesis in the MSSM
We revisit the electroweak baryogenesis within the context of the minimal
supersymmetric standard model (MSSM), studying its potential collider
signatures. We find that this mechanism of baryogenesis does not give a new CP
violating signal at the -factories. The first circumstantial evidence may
come from enhanced or mixing. If a light right-handed scalar top
and Higgs are found as required, a linear collider represents the best
possibility for confirming the scenario.Comment: 5 pages, 2 figures. Minor typos fixed. Reference Adde
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