602 research outputs found
Disentangling the timescales behind the non-perturbative heavy quark potential
The static part of the heavy quark potential has been shown to be closely
related to the spectrum of the rectangular Wilson loop. In particular the
lowest lying positive frequency peak encodes the late time evolution of the
two-body system, characterized by a complex potential. While initial studies
assumed a perfect separation of early and late time physics, where a simple
Lorentian (Breit-Wigner) shape suffices to describe the spectral peak, we argue
that scale decoupling in general is not complete. Thus early time, i.e.
non-potential effects, significantly modify the shape of the lowest peak. We
derive on general grounds an improved peak distribution that reflects this
fact. Application of the improved fit to non-perturbative lattice QCD spectra
now yields a potential that is compatible with a transition to a deconfined
screening plasma.Comment: 5 pages, 3 figure
From the chiral magnetic wave to the charge dependence of elliptic flow
The quark-gluon plasma formed in heavy ion collisions contains charged chiral
fermions evolving in an external magnetic field. At finite density of electric
charge or baryon number (resulting either from nuclear stopping or from
fluctuations), the triangle anomaly induces in the plasma the Chiral Magnetic
Wave (CMW). The CMW first induces a separation of the right and left chiral
charges along the magnetic field; the resulting dipolar axial charge density in
turn induces the oppositely directed vector charge currents leading to an
electric quadrupole moment of the quark-gluon plasma. Boosted by the strong
collective flow, the electric quadrupole moment translates into the charge
dependence of the elliptic flow coefficients, so that
(at positive net charge). Using the latest quantitative simulations of the
produced magnetic field and solving the CMW equation, we make further
quantitative estimates of the produced splitting and its centrality
dependence. We compare the results with the available experimental data.Comment: Contains 12 pages, 6 figures, written as a proceeding for the talk of
Y. Burnier at the conference "P and CP-odd Effects in Hot and Dense Matter
2012" held in BN
Neurohormonal consequences of diuretics in different cardiovascular syndromes
Diuretics have long been used to lower blood pressure in hypertensive patients or to control body fluid and electrolyte homeostasis in diseases such as congestive heart failure, chronic renal failure or cirrhosis. The initial response to diuretics is negative sodium and fluid balance. The diuretic-induced loss of salt and water activates several hormonal systems such as vasopressin, the renin-angiotensin-aldosterone system or the sympathetic nervous system which tend to compensate for the changes in sodium and water balance. This neurohormonal response may have important clinical implications. Thus, the activation of the renin-angiotensin-aldosterone cascade appears to be partially responsible for the flat dose-blood pressure response curve of thiazides in hypertensive patients. It may also be responsible for the difference between responders and non-responders to diuretic therapy and for the development of side-effects such as hypokalaemia, metabolic alkalosis or hyponatraemia. There are several ways to prevent the undesirable consequences of the neurohormonal responses to diuretics. The first is to use low doses of these agents. It is also possible to combine them with agents that block the activity of the renin-angiotensin-aldosterone system such as ACE inhibitors or in combination with drugs that reduce aldosterone secretion such as calcium antagonists. The development of drugs able to enhance urinary sodium excretion and to reduce simultaneously the activity of the renin-angiotensin-aldosterone system may offer a new interesting alternative. This might perhaps be achieved in the future with the administration of neutral endopeptidase inhibitors which interfere with the enzymatic degradation of atrial natriuretic peptid
Can an odd number of fermions be created due to chiral anomaly?
We describe a possibility of creation of an odd number of fractionally
charged fermions in 1+1 dimensional Abelian Higgs model. We point out that for
1+1 dimensions this process does not violate any symmetries of the theory, nor
makes it mathematically inconsistent. We construct the proper definition of the
fermionic determinant in this model and underline its non-trivial features that
are of importance for realistic 3+1 dimensional models with fermion number
violation.Comment: 12 pages revtex, 2 figure
Heavy Quark Interactions and Quarkonium Binding
We consider heavy quark interactions in quenched and unquenched lattice QCD.
In a region just above the deconfinement point, non-Abelian gluon polarization
leads to a strong increase in the binding. Comparing quark-antiquark and
quark-quark interaction, the dependence of the binding on the separation
distance is found to be the same for the colorless singlet and
the colored anti-triplet state. In a potential model description of
in-medium behavior, this enhancement of the binding leads to a
survival up to temperatures of 1.5 or higher; it could also result in
flow.Comment: 8 pages, 8 Figures; invited talk at "Strangeness in Quark Matter
2008", Beijing/China, to appear in the Proceeding
Towards flavour diffusion coefficient and electrical conductivity without ultraviolet contamination
By subtracting from a recent lattice measurement of the thermal
vector-current correlator the known 5-loop vacuum contribution, we demonstrate
that the remainder is small and shows no visible short-distance divergence. It
can therefore in principle be subjected to model-independent analytic
continuation. Testing a particular implementation, we obtain estimates for the
flavour-diffusion coefficient (2 pi T D \gsim 0.8) and electrical conductivity
which are significantly smaller than previous results. Although systematic
errors remain beyond control at present, some aspects of our approach could be
of a wider applicability.Comment: 7 pages. v2: clarifications added, published versio
On electroweak baryogenesis in the littlest Higgs model with T parity
We study electroweak baryogenesis within the framework of the littlest Higgs
model with T parity. This model has shown characteristics of a strong
first-order electroweak phase transition, which is conducive to baryogenesis in
the early Universe. In the T parity symmetric theory, there are two gauge
sectors, viz., the T-even and the T-odd ones. We observe that the effect of the
T-parity symmetric interactions between the T-odd and the T-even gauge bosons
on gauge-higgs energy functional is quite small, so that these two sectors can
be taken to be independent. The T-even gauge bosons behave like the Standard
Model gauge bosons, whereas the T-odd ones are instrumental in stabilizing the
Higgs mass. For the T-odd gauge bosons in the symmetric and asymmetric phases
and for the T-even gauge bosons in the asymmetric phase, we obtain, using the
formalism of Arnold and McLerran, very small values of the ratio, (Baryon
number violation rate/Universe expansion rate). We observe that this result, in
conjunction with the scenario of inverse phase transition in the present work
and the value of the ratio obtained from the lattice result of sphaleron
transition rate in the symmetric phase, can provide us with a plausible
baryogenesis scenario.Comment: 13 pages, 2 figures, published version, references modifie
A prospective observational study comparing a non-operator dependent automatic PWV analyser to pulse pressure, in assessing arterial stiffness in hemodialysis.
BACKGROUND: Chronic kidney disease (CKD) accelerates vascular stiffening related to age. Arterial stiffness may be evaluated measuring the carotid-femoral pulse wave velocity (PWV) or more simply, as recommended by KDOQI, monitoring pulse pressure (PP). Both correlate to survival and incidence of cardiovascular disease. PWV can also be estimated on the brachial artery using a Mobil-O-Graph; a non-operator dependent automatic device. The aim was to analyse whether, in a dialysis population, PWV obtained by Mobil-O-Graph (MogPWV) is more sensitive for vascular aging than PP.
METHODS: A cohort of 143 patients from 4 dialysis units has been followed measuring MogPWV and PP every 3 to 6 months and compared to a control group with the same risk factors but an eGFR > 30 ml/min.
RESULTS: MogPWV contrarily to PP did discriminate the dialysis population from the control group. The mean difference translated in age between the two populations was 8.4 years. The increase in MogPWV, as a function of age, was more rapid in the dialysis group. 13.3% of the dialysis patients but only 3.0% of the control group were outliers for MogPWV. The mortality rate (16 out of 143) was similar in outliers and inliers (7.4 and 8.0%/year). Stratifying patients according to MogPWV, a significant difference in survival was seen. A high parathormone (PTH) and to be dialysed for a hypertensive nephropathy were associated to a higher baseline MogPWV.
CONCLUSIONS: Assessing PWV on the brachial artery using a Mobil-O-Graph is a valid and simple alternative, which, in the dialysis population, is more sensitive for vascular aging than PP. As demonstrated in previous studies PWV correlates to mortality. Among specific CKD risk factors only PTH is associated with a higher baseline PWV.
TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02327962
Right-Handed Sector Leptogenesis
Instead of creating the observed baryon asymmetry of the universe by the
decay of right-handed (RH) neutrinos to left-handed leptons, we propose to
generate it dominantly by the decay of the RH neutrinos to RH leptons. This
mechanism turns out to be successful in large regions of parameter space. It
may work, in particular, at a scale as low as ~TeV, with no need to
invoke quasi-degenerate RH neutrino masses to resonantly enhance the asymmetry.
Such a possibility can be probed experimentally by the observation at colliders
of a singlet charged Higgs particle and of RH neutrinos. Other mechanisms which
may lead to successful leptogenesis from the RH lepton sector interactions are
also briefly presented. The incorporation of these scenarios in left-right
symmetric and unified models is discussed.Comment: 14 pages, latex, axodraw; minor clarifications and references added,
extended discussion of the signatures at collider
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