76 research outputs found
MiniBooNE and LSND data: non-standard neutrino interactions in a (3+1) scheme versus (3+2) oscillations
The recently observed event excess in MiniBooNE anti-neutrino data is in
agreement with the LSND evidence for electron anti-neutrino appearance. We
propose an explanation of these data in terms of a (3+1) scheme with a sterile
neutrino including non-standard neutrino interactions (NSI) at neutrino
production and detection. The interference between oscillations and NSI
provides a source for CP violation which we use to reconcile different results
from neutrino and anti-neutrino data. Our best fit results imply NSI at the
level of a few percent relative to the standard weak interaction, in agreement
with current bounds. We compare the quality of the NSI fit to the one obtained
within the (3+1) and (3+2) pure oscillation frameworks. We also briefly comment
on using NSI (in an effective two-flavour framework) to address a possible
difference in neutrino and anti-neutrino results from the MINOS experiment.Comment: 28 pages, 9 figures, discussion improved, new appendix added,
conclusions unchange
The Dark Side of the Electroweak Phase Transition
Recent data from cosmic ray experiments may be explained by a new GeV scale
of physics. In addition the fine-tuning of supersymmetric models may be
alleviated by new O(GeV) states into which the Higgs boson could decay. The
presence of these new, light states can affect early universe cosmology. We
explore the consequences of a light (~ GeV) scalar on the electroweak phase
transition. We find that trilinear interactions between the light state and the
Higgs can allow a first order electroweak phase transition and a Higgs mass
consistent with experimental bounds, which may allow electroweak baryogenesis
to explain the cosmological baryon asymmetry. We show, within the context of a
specific supersymmetric model, how the physics responsible for the first order
phase transition may also be responsible for the recent cosmic ray excesses of
PAMELA, FERMI etc. We consider the production of gravity waves from this
transition and the possible detectability at LISA and BBO
Stochastic Gravity: Theory and Applications
Whereas semiclassical gravity is based on the semiclassical Einstein equation
with sources given by the expectation value of the stress-energy tensor of
quantum fields, stochastic semiclassical gravity is based on the
Einstein-Langevin equation, which has in addition sources due to the noise
kernel.In the first part, we describe the fundamentals of this new theory via
two approaches: the axiomatic and the functional. In the second part, we
describe three applications of stochastic gravity theory. First, we consider
metric perturbations in a Minkowski spacetime: we compute the two-point
correlation functions for the linearized Einstein tensor and for the metric
perturbations. Second, we discuss structure formation from the stochastic
gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in
the gravitational background of a quasi-static black hole.Comment: 75 pages, no figures, submitted to Living Reviews in Relativit
Stochastic Gravity: Theory and Applications
Whereas semiclassical gravity is based on the semiclassical Einstein equation
with sources given by the expectation value of the stress-energy tensor of
quantum fields, stochastic semiclassical gravity is based on the
Einstein-Langevin equation, which has in addition sources due to the noise
kernel. In the first part, we describe the fundamentals of this new theory via
two approaches: the axiomatic and the functional. In the second part, we
describe three applications of stochastic gravity theory. First, we consider
metric perturbations in a Minkowski spacetime, compute the two-point
correlation functions of these perturbations and prove that Minkowski spacetime
is a stable solution of semiclassical gravity. Second, we discuss structure
formation from the stochastic gravity viewpoint. Third, we discuss the
backreaction of Hawking radiation in the gravitational background of a black
hole and describe the metric fluctuations near the event horizon of an
evaporating black holeComment: 100 pages, no figures; an update of the 2003 review in Living Reviews
in Relativity gr-qc/0307032 ; it includes new sections on the Validity of
Semiclassical Gravity, the Stability of Minkowski Spacetime, and the Metric
Fluctuations of an Evaporating Black Hol
Phenomenology and Cosmology of an Electroweak Pseudo-Dilaton and Electroweak Baryons
In many strongly-interacting models of electroweak symmetry breaking the
lowest-lying observable particle is a pseudo-Goldstone boson of approximate
scale symmetry, the pseudo-dilaton. Its interactions with Standard Model
particles can be described using a low-energy effective nonlinear chiral
Lagrangian supplemented by terms that restore approximate scale symmetry,
yielding couplings of the pseudo-dilaton that differ from those of a Standard
Model Higgs boson by fixed factors. We review the experimental constraints on
such a pseudo-dilaton in light of new data from the LHC and elsewhere. The
effective nonlinear chiral Lagrangian has Skyrmion solutions that may be
identified with the `electroweak baryons' of the underlying
strongly-interacting theory, whose nature may be revealed by the properties of
the Skyrmions. We discuss the finite-temperature electroweak phase transition
in the low-energy effective theory, finding that the possibility of a
first-order electroweak phase transition is resurrected. We discuss the
evolution of the Universe during this transition and derive an
order-of-magnitude lower limit on the abundance of electroweak baryons in the
absence of a cosmological asymmetry, which suggests that such an asymmetry
would be necessary if the electroweak baryons are to provide the cosmological
density of dark matter. We revisit estimates of the corresponding
spin-independent dark matter scattering cross section, with a view to direct
detection experiments.Comment: 34 pages, 4 figures, additional references adde
Low-Energy Probes of a Warped Extra Dimension
We investigate a natural realization of a light Abelian hidden sector in an
extended Randall-Sundrum (RS) model. In addition to the usual RS bulk we
consider a second warped space containing a bulk U(1)_x gauge theory with a
characteristic IR scale of order a GeV. This Abelian hidden sector can couple
to the standard model via gauge kinetic mixing on a common UV brane. We show
that if such a coupling induces significant mixing between the lightest U(1)_x
gauge mode and the standard model photon and Z, it can also induce significant
mixing with the heavier U(1)_x Kaluza-Klein (KK) modes. As a result it might be
possible to probe several KK modes in upcoming fixed-target experiments and
meson factories, thereby offering a new way to investigate the structure of an
extra spacetime dimension.Comment: 26 pages, 1 figure, added references, corrected minor typos, same as
journal versio
Discerning Secluded Sector gauge structures
New fundamental particles, charged under new gauge groups and only weakly
coupled to the standard sector, could exist at fairly low energy scales. In
this article we study a selection of such models, where the secluded group
either contains a softly broken U(1) or an unbroken SU(N). In the Abelian case
new {\gamma}v gauge bosons can be radiated off and decay back into visible
particles. In the non-Abelian case there will not only be a cascade in the
hidden sector, but also hadronization into new {\pi}v and {\rho}v mesons that
can decay back. This framework is developed to be applicable both for e+e- and
pp collisions, but for these first studies we concentrate on the former process
type. For each Abelian and non-Abelian group we study three different scenarios
for the communication between the standard sector and the secluded one. We
illustrate how to distinguish the various characteristics of the models and
especially study to what extent the underlying gauge structure can be
determined experimentally.Comment: removed extra figure
Variable alterations of the microbiota, without metabolic or immunological change, following faecal microbiota transplantation in patients with chronic pouchitis
© 2015 The Authors. Published by Springer Nature. This is an open access article available under a Creative Commons licence.
The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1038/srep12955Faecal microbiota transplantation (FMT) is effective in the treatment of Clostridium difficile infection, where efficacy correlates with changes in microbiota diversity and composition. The effects of FMT on recipient microbiota in inflammatory bowel diseases (IBD) remain unclear. We assessed the effects of FMT on microbiota composition and function, mucosal immune response, and clinical outcome in patients with chronic pouchitis. Eight patients with chronic pouchitis (current PDAI ‰7) were treated with FMT via nasogastric administration. Clinical activity was assessed before and four weeks following FMT. Faecal coliform antibiotic sensitivities were analysed, and changes in pouch faecal and mucosal microbiota assessed by 16S rRNA gene pyrosequencing and 1 H NMR spectroscopy. Lamina propria dendritic cell phenotype and cytokine profiles were assessed by flow cytometric analysis and multiplex assay. Following FMT, there were variable shifts in faecal and mucosal microbiota composition and, in some patients, changes in proportional abundance of species suggestive of a 'healthier' pouch microbiota. However, there were no significant FMT-induced metabolic or immunological changes, or beneficial clinical response. Given the lack of clinical response following FMT via a single nasogastric administration our results suggest that FMT/bacteriotherapy for pouchitis patients requires further optimisation.Published versio
Probable or improbable universe? Correlating electroweak vacuum instability with the scale of inflation
TRIM27 Negatively Regulates NOD2 by Ubiquitination and Proteasomal Degradation
NOD2, the nucleotide-binding domain and leucine-rich repeat containing gene family (NLR) member 2 is involved in mediating antimicrobial responses. Dysfunctional NOD2 activity can lead to severe inflammatory disorders, but the regulation of NOD2 is still poorly understood. Recently, proteins of the tripartite motif (TRIM) protein family have emerged as regulators of innate immune responses by acting as E3 ubiquitin ligases. We identified TRIM27 as a new specific binding partner for NOD2. We show that NOD2 physically interacts with TRIM27 via the nucleotide-binding domain, and that NOD2 activation enhances this interaction. Dependent on functional TRIM27, ectopically expressed NOD2 is ubiquitinated with K48-linked ubiquitin chains followed by proteasomal degradation. Accordingly, TRIM27 affects NOD2-mediated pro-inflammatory responses. NOD2 mutations are linked to susceptibility to Crohns disease. We found that TRIM27 expression is increased in Crohns disease patients, underscoring a physiological role of TRIM27 in regulating NOD2 signaling. In HeLa cells, TRIM27 is partially localized in the nucleus. We revealed that ectopically expressed NOD2 can shuttle to the nucleus in a Walker A dependent manner, suggesting that NOD2 and TRIM27 might functionally cooperate in the nucleus. We conclude that TRIM27 negatively regulates NOD2-mediated signaling by degradation of NOD2 and suggest that TRIM27 could be a new target for therapeutic intervention in NOD2-associated diseases.Funding Agencies|German Research Foundation (DFG)|SFB670-NG01|Swedish Society of Medicine||Regional Research Council of South-East Sweden (FORSS)||Swedish Research Council division of Medicine||Gustav V 90th anniversary foundation||Italian Telethon Foundation||DFG|SE 1122/2-1|</p
- …