1,891 research outputs found
A test of first order scaling in Nf=2 QCD
We complete our analysis of Nf=2 QCD based on the lattice staggered fermion
formulation. Using a series of Monte Carlo simulations at fixed (amq*Ls^yh) one
is able to test the universality class with given critical exponent yh. This
strategy has been used to test the O(4) universality class and it has been
presented at the previous Lattice conferences. No agreement was found with
simulations in the mass range amq=[0.01335,0.15] using lattices with Ls=16 up
to 32 and Lt=4. With the same strategy, we now investigate the possibility of a
first order transition using a new set of Monte Carlo data corresponding to
yh=3 in the same mass and volume range as the one used for O(4). A substantial
agreement is observed both in the specific heat scaling and in the scaling of
the chiral condensate, while the chiral susceptibilities still presents visible
deviation from scaling in the mass range explored.Comment: 5 pages, 6 figures, Presented at the XXV International Symposium on
Lattice Field Theory, July 30 - August 4 2007, Regensburg, German
Two flavor QCD and confinement - II
This paper is part of a program of investigation of the chiral transition in
Nf=2 QCD, started in Phys.Rev.D72:114510,2005. Progress is reported on the
understanding of some possible systematic errors. A direct test of first order
scaling is presented.Comment: 7 pages, 6 figure
On the phase diagram of the Higgs SU(2) model
The Higgs SU(2) model with fixed Higgs length is usually believed to have two
different phases at high gauge coupling (\beta), separated by a line of first
order transitions but not distinuguished by any typical symmetry associated
with a local order parameter, as first proved by Fradkin and Shenker. We show
that in regions of the parameter space where it is usually supposed to be a
first order phase transition only a smooth crossover is in fact present.Comment: 6 pages, 6 figures. Talk presented at The XXVI International
Symposium on Lattice Field Theory, July 14 - 19, 2008 - Williamsburg,
Virginia, US
A test of first order scaling in Nf =2 QCD: a progress report
We present the status of our analysis on the order of the finite temperature
transition in QCD with two flavors of degenerate fermions. Our new simulations
on large lattices support the hypothesis of the first order nature of the
transition, showing a preliminary two state signal. We will discuss the
implications and the next steps in our analysis.Comment: 6 pages, 4 figures. Talk presented at The XXVI International
Symposium on Lattice Field Theory, July 14 - 19, 2008 - Williamsburg,
Virginia, US
To Look Beyond Vasospasm in Aneurysmal Subarachnoid Haemorrhage.
Delayed cerebral vasospasm has classically been considered the most important and treatable cause of mortality and morbidity in patients with aneurysmal subarachnoid hemorrhage (aSAH). Secondary ischemia (or delayed ischemic neurological deficit, DIND) has been shown to be the leading determinant of poor clinical outcome in patients with aSAH surviving the early phase and cerebral vasospasm has been attributed to being primarily responsible. Recently, various clinical trials aimed at treating vasospasm have produced disappointing results. DIND seems to have a multifactorial etiology and vasospasm may simply represent one contributing factor and not the major determinant. Increasing evidence shows that a series of early secondary cerebral insults may occur following aneurysm rupture (the so-called early brain injury). This further aggravates the initial insult and actually determines the functional outcome. A better understanding of these mechanisms and their prevention in the very early phase is needed to improve the prognosis. The aim of this review is to summarize the existing literature on this topic and so to illustrate how the presence of cerebral vasospasm may not necessarily be a prerequisite for DIND development. The various factors determining DIND that worsen functional outcome and prognosis are then discussed
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