806 research outputs found
Electroweak Baryogenesis with dimension-6 Higgs interactions
We present the computation of the baryon asymmetry in the SM amplified by
dimension-6 Higgs interactions using the WKB approximation. Analyzing the
one-loop potential it turns out that the phase transition is strongly first
order in a wide range of the parameters. It is ensured not to wash out the net
baryon number gained previously even for Higgs masses up to at least 170 GeV.
In addition dimension-6 operators induce new sources of CP violation. Novel
source terms which enhance the generated baryon asymmetry emerge in the
transport equations. This model predicts a baryon to entropy ratio close to the
observed value for a large part of the parameter space.Comment: 10 pages, 4 figures, Talk given at the 8th International Moscow
School of Physic
The Baryon asymmetry in the Standard Model with a low cut-off
We study the generation of the baryon asymmetry in a variant of the standard
model, where the Higgs field is stabilized by a dimension-six interaction.
Analyzing the one-loop potential, we find a strong first order electroweak
phase transition for Higgs masses up to at least 170 GeV. Dimension-six
operators induce also new sources of CP violation. We compute the baryon
asymmetry in the WKB approximation. Novel source terms in the transport
equations enhance the generated baryon asymmetry. For a wide range of
parameters the model predicts a baryon asymmetry close to the observed value.Comment: 22 pages, latex, 6 figure
Impact of Acute Kidney Injury and CKD on Adverse Outcomes in Critically Ill Septic Patients
Introduction: Chronic kidney disease (CKD) and acute kidney injury (AKI) are strongly associated with excess morbidity and mortality and frequently co-occur in critically ill septic patients, but how their interplay affects clinical outcomes is not well elucidated. Methods: We conducted a single-center, retrospective cohort study of 2632 adult patients admitted to the intensive care unit (ICU) with severe sepsis or septic shock. Subjects were classified into 6 groups according to baseline CKD (no-CKD: estimated glomerular filtration rate [eGFR] ≥60; CKD: eGFR 15−59 ml/min per 1.73 m2) and incident AKI by the Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine criteria (no-AKI, AKI stage 1, AKI stages ≥2) during ICU stay. Study outcomes were 90-day mortality (in hospital or within 90 days of discharge) and incident/progressive CKD. Results: Prevalent CKD was 46% and incident AKI was 57%. Adjusted hazard ratios (95% confidence intervals) for 90-day mortality relative to the reference group of no-CKD/no-AKI were 1.5 (1.1−2.0) in no-CKD/AKI stage 1, 2.4 (1.9−3.1) in no-CKD/AKI stages≥2, 1.1 (0.8−1.4) in CKD/no-AKI, 1.2 (0.9−1.6) in CKD/AKI stage 1, and 2.2 (1.7−2.9) in CKD/AKI stages ≥2. A similar trend was observed for incident/progressive CKD during a median follow-up of 15.3 months. Conclusion: Stage 1 AKI on CKD was not associated with an independent increased risk of adverse outcomes in critically ill septic patients. AKI stages ≥2 on CKD and any level of AKI in no-CKD patients were strongly and independently associated with adverse outcomes. Sepsis-associated stage 1 AKI on CKD may represent distinct underlying pathophysiology, with more prerenal cases and less severe de novo intrinsic damage, which needs further investigation
A formally verified compiler back-end
This article describes the development and formal verification (proof of
semantic preservation) of a compiler back-end from Cminor (a simple imperative
intermediate language) to PowerPC assembly code, using the Coq proof assistant
both for programming the compiler and for proving its correctness. Such a
verified compiler is useful in the context of formal methods applied to the
certification of critical software: the verification of the compiler guarantees
that the safety properties proved on the source code hold for the executable
compiled code as well
Noncommutative vector bundles over fuzzy CP^N and their covariant derivatives
We generalise the construction of fuzzy CP^N in a manner that allows us to
access all noncommutative equivariant complex vector bundles over this space.
We give a simplified construction of polarization tensors on S^2 that
generalizes to complex projective space, identify Laplacians and natural
noncommutative covariant derivative operators that map between the modules that
describe noncommuative sections. In the process we find a natural
generalization of the Schwinger-Jordan construction to su(n) and identify
composite oscillators that obey a Heisenberg algebra on an appropriate Fock
space.Comment: 34 pages, v2 contains minor corrections to the published versio
Semi-Analytical Approaches to Local Electroweak Baryogenesis
We examine two semi-analytical methods for estimating the baryon asymmetry of
the universe (BAU) generated in scenarios of ``local'' electroweak baryogenesis
(in which the requisite baryon number violation and CP violation occur together
in space and time). We work with the standard electroweak theory augmented by
the addition of a CP violating dimension six operator. We work in the context
of a first order phase transition, but the processes we describe can also occur
during the evolution of a network of topological defects. Both the approaches
we explore deal with circumstances where the bubble walls which convert the
high temperature phase to the low temperature phase are thin and rapidly
moving. We first consider the dynamics of localized configurations with winding
number one which remain in the broken phase immediately after the bubble wall
has passed. Their subsequent decay can anomalously produce fermions. In a
prelude to our analysis of this effect, we demonstrate how to define the C and
CP symmetries in the bosonic sector of the electroweak theory when
configurations with nonzero winding are taken into account. Second, we consider
the effect of the passage of the wall itself on configurations which happen to
be near the crest of the ridge between vacua as the wall arrives. We find that
neither of the simple approaches followed here can be pushed far enough to
obtain a convincing estimate of the BAU which is produced. A large scale
numerical treatment seems necessary.Comment: 31 pages, revtex, one figure, epsf. This is the version to appear in
Phys Rev D; only changes are small clarification
Probing natural SUSY from stop pair production at the LHC
We consider the natural supersymmetry scenario in the framework of the
R-parity conserving minimal supersymmetric standard model (called natural MSSM)
and examine the observability of stop pair production at the LHC. We first scan
the parameters of this scenario under various experimental constraints,
including the SM-like Higgs boson mass, the indirect limits from precision
electroweak data and B-decays. Then in the allowed parameter space we study the
stop pair production at the LHC followed by the stop decay into a top quark
plus a lightest neutralino or into a bottom quark plus a chargino. From
detailed Monte Carlo simulations of the signals and backgrounds, we find the
two decay modes are complementary to each other in probing the stop pair
production, and the LHC with TeV and 100 luminosity is
capable of discovering the stop predicted in natural MSSM up to 450 GeV. If no
excess events were observed at the LHC, the 95% C.L. exclusion limits of the
stop masses can reach around 537 GeV.Comment: 19 pages, 10 figures, version accepted by JHE
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