84,432 research outputs found
Zoology of condensed matter: Framids, ordinary stuff, extra-ordinary stuff
We classify condensed matter systems in terms of the spacetime symmetries
they spontaneously break. In particular, we characterize condensed matter
itself as any state in a Poincar\'e-invariant theory that spontaneously breaks
Lorentz boosts while preserving at large distances some form of spatial
translations, time-translations, and possibly spatial rotations. Surprisingly,
the simplest, most minimal system achieving this symmetry breaking
pattern---the "framid"---does not seem to be realized in Nature. Instead,
Nature usually adopts a more cumbersome strategy: that of introducing internal
translational symmetries---and possibly rotational ones---and of spontaneously
breaking them along with their space-time counterparts, while preserving
unbroken diagonal subgroups. This symmetry breaking pattern describes the
infrared dynamics of ordinary solids, fluids, superfluids, and---if they
exist---supersolids. A third, "extra-ordinary", possibility involves replacing
these internal symmetries with other symmetries that do not commute with the
Poincar\'e group, for instance the galileon symmetry, supersymmetry or gauge
symmetries. Among these options, we pick the systems based on the galileon
symmetry, the "galileids", for a more detailed study. Despite some similarity,
all different patterns produce truly distinct physical systems with different
observable properties. For instance, the low-energy scattering
amplitudes for the Goldstone excitations in the cases of framids, solids and
galileids scale respectively as , , and . Similarly the energy
momentum tensor in the ground state is "trivial" for framids (),
normal for solids () and even inhomogenous for galileids.Comment: 58 pages, 1 table, 1 free cut-and-paste project for rainy days in
Appendi
The Composite Twin Higgs scenario
Based on an explicit model, we propose and discuss the generic features of a
possible implementation of the Twin Higgs program in the context of composite
Higgs models. We find that the Twin Higgs quadratic divergence cancellation
argument can be uplifted to a genuine protection of the Higgs potential, based
on symmetries and selection rules, but only under certain conditions which are
not fulfilled in some of the existing models. We also find that a viable
scenario, not plagued by a massless Twin Photon, can be obtained by not gauging
the Twin Hypercharge and taking this as the only source of Twin Symmetry
breaking at a very high scale.Comment: 19 pages; v2: typos and notation corrected, results unchanged; v3:
published versio
Prospects for direct detection of dark matter in an effective theory approach
We perform the first comprehensive analysis of the prospects for direct
detection of dark matter with future ton-scale detectors in the general
11-dimensional effective theory of isoscalar dark matter-nucleon interactions
mediated by a heavy spin-1 or spin-0 particle. The theory includes 8 momentum
and velocity dependent dark matter-nucleon interaction operators, besides the
familiar spin-independent and spin-dependent operators. From a variegated
sample of 27 benchmark points selected in the parameter space of the theory, we
simulate independent sets of synthetic data for ton-scale Germanium and Xenon
detectors. From the synthetic data, we then extract the marginal posterior
probability density functions and the profile likelihoods of the model
parameters. The associated Bayesian credible regions and frequentist confidence
intervals allow us to assess the prospects for direct detection of dark matter
at the 27 benchmark points. First, we analyze the data assuming the knowledge
of the correct dark matter nucleon-interaction type, as it is commonly done for
the familiar spin-independent and spin-dependent interactions. Then, we analyze
the simulations extracting the dark matter-nucleon interaction type from the
data directly, in contrast to standard analyses. This second approach requires
an extensive exploration of the full 11-dimensional parameter space of the dark
matter-nucleon effective theory. Interestingly, we identify 5 scenarios where
the dark matter mass and the dark matter-nucleon interaction type can be
reconstructed from the data simultaneously. We stress the importance of
extracting the dark matter nucleon-interaction type from the data directly,
discussing the main challenges found addressing this complex 11-dimensional
problem.Comment: 23 pages, 7 figures, replaced to match the published versio
Asymptotic behavior and existence of solutions for singular elliptic equations
We study the asymptotic behavior, as tends to infinity, of solutions
for the homogeneous Dirichlet problem associated to singular semilinear
elliptic equations whose model is where is an open, bounded subset of \RN and is a
bounded function. We deal with the existence of a limit equation under two
different assumptions on : either strictly positive on every compactly
contained subset of or only nonnegative. Through this study we deduce
optimal existence results of positive solutions for the homogeneous Dirichlet
problem associated to Comment: 31 page
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