40,870 research outputs found
Two examples of non strictly convex large deviations
We present two examples of a large deviations principle where the rate
function is not strictly convex. This is motivated by a model used in
mathematical finance (the Heston model), and adds a new item to the zoology of
non strictly convex large deviations. For one of these examples, we show that
the rate function of the Cramer-type of large deviations coincides with that of
the Freidlin-Wentzell when contraction principles are applied.Comment: 11 page
Hint of Lepton Flavour Non-Universality in Meson Decays
The LHCb collaboration has recently presented their result on R_K = BR(B+ ->
K+ mu+ mu-)/ BR(B+ -> K+ e+ e-) for the dilepton invariant mass bin m_{ll}^2 =
1-6 GeV^2 (l = mu, e). The measurement shows an intriguing 2.6 sigma deviation
from the Standard Model (SM) prediction. In view of this, we study model
independent New Physics (NP) explanations of R_K consistent with other
measurements involving b -> s l l transition, relaxing the assumption of lepton
universality. We perform a Bayesian statistical fit to the NP Wilson
Coefficients and compare the Bayes Factors of the different hypotheses in order
to quantify their goodness-of-fit. We show that the data slightly favours NP in
the muon sector over NP in the electron sector.Comment: Final version, to appear in JHE
Spacelike hypersurfaces in standard static spacetimes
In this work we study spacelike hypersurfaces immersed in spatially open
standard static spacetimes with complete spacelike slices. Under appropriate
lower bounds on the Ricci curvature of the spacetime in directions tangent to
the slices, we prove that every complete CMC hypersurface having either bounded
hyperbolic angle or bounded height is maximal. Our conclusions follow from
general mean curvature estimates for spacelike hypersurfaces. In case where the
spacetime is a Lorentzian product with spatial factor of nonnegative Ricci
curvature and sectional curvatures bounded below, we also show that a complete
maximal hypersurface not intersecting a spacelike slice is itself a slice. This
result is obtained from a gradient estimate for parametric maximal
hypersurfaces.Comment: 50 page
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