981 research outputs found
Constraining the QCD phase diagram by tricritical lines at imaginary chemical potential
We present unambiguous evidence from lattice simulations of QCD with three
degenerate quark species for two tricritical points in the (T,m) phase diagram
at fixed imaginary \mu/T=i\pi/3 mod 2\pi/3, one in the light and one in the
heavy mass regime. These represent the boundaries of the chiral and
deconfinement critical lines continued to imaginary chemical potential,
respectively. It is demonstrated that the shape of the deconfinement critical
line for real chemical potentials is dictated by tricritical scaling and
implies the weakening of the deconfinement transition with real chemical
potential. The generalization to non-degenerate and light quark masses is
discussed.Comment: 4 pages, 5 figure
Use of recurrence quantification analysis to examine associations between changes in text structure across an expressive writing intervention and reductions in distress symptoms in women wth breast cancer
The current study presents an exploratory analysis of using Recurrence Quantification Analysis (RQA) to analyze text data from an Expressive Writing Intervention (EWI) for Danish women treated for Breast Cancer. The analyses are based on the analysis of essays from a subsample with the average age 54.6 years (SD = 9.0), who completed questionnaires for cancer-related distress (IES) and depression symptoms (BDI-SF). The results show a significant association between an increase in recurrent patterns of text structure from first to last writing session and a decrease in cancer-related distress at 3 months post-intervention. Furthermore, the change in structure from first to last essay displayed a moderate, but significant correlation with change in cancer-related distress from baseline to 9 months post-intervention. The results suggest that changes in recurrence patterns of text structure might be an indicator of cognitive restructuring that leads to amelioration of cancer-specific distress
String Breaking in Non-Abelian Gauge Theories with Fundamental Matter Fields
We present clear numerical evidence for string breaking in three-dimensional
SU(2) gauge theory with fundamental bosonic matter through a mixing analysis
between Wilson loops and meson operators representing bound states of a static
source and a dynamical scalar. The breaking scale is calculated in the
continuum limit. In units of the lightest glueball we find . The implications of our results for QCD are discussed.Comment: 4 pages, 2 figures; equations (4)-(6) corrected, numerical results
and conclusions unchange
Breakdown of staggered fermions at nonzero chemical potential
The staggered fermion determinant is complex when the quark chemical
potential mu is nonzero. Its fourth root, used in simulations with dynamical
fermions, will have phase ambiguities that become acute when Re mu is
sufficiently large. We show how to resolve these ambiguities, but our
prescription only works very close to the continuum limit. We argue that this
regime is far from current capabilities. Other procedures require being even
closer to the continuum limit, or fail altogether, because of unphysical
discontinuities in the measure. At zero temperature the breakdown is expected
when Re mu is greater than approximately half the pion mass. Estimates of the
location of the breakdown at nonzero temperature are less certain.Comment: 6 pages RevTeX, 2 figures. Returning to v5 after erroneous
replacement. Apologie
A Method Off the Beaten Track: Refining Creative Writing Process through Practice-led Research
How can you improve your writing processes and your creative projects by examining your own working conditions? In this article, we address this question and the possibilities and challenges of the method called âpractice-led researchâ, which is a method off the beaten track in media production studies. We examine assignments by students from the educational program of âScreenplay Developmentâ at the University of Southern Den-mark. Our purpose is to clarify how the students have used practice-led research to enhance their screenwriting, and whether this method has contributed to their talent development. The theoretical framework in the article is constituted by Donald Schönâs (2013) practice epistemology. As our analytical lens we use Robin Nelsonâs (2013) modes of thinking, as well as talent development theories by Anders Ericsson (Ericsson & Pool, 2016) and Mihalyi Csikszentmihalyi (1996). Based on our findings, we suggest how to get started youâre your creative writing and improve your writing processes
Towards a controlled study of the QCD critical point
The phase diagram of QCD, as a function of temperature T and quark chemical
potential mu, may contain a critical point (mu_E,T_E) whose non-perturbative
nature makes it a natural object of lattice studies. However, the sign problem
prevents the application of standard Monte Carlo techniques at non-zero baryon
density. We have been pursuing an approach free of the sign problem, where the
chemical potential is taken as imaginary and the results are Taylor-expanded in
mu/T about mu=0, then analytically continued to real mu.
Within this approach we have determined the sensitivity of the critical
chemical potential mu_E to the quark mass, d(\mu_E)^2/dm_q|_{\mu_E=0}. Our
study indicates that the critical point moves to {\em smaller} chemical
potential as the quark mass {\em increases}. This finding, contrary to common
wisdom, implies that the deconfinement crossover, which takes place in QCD at
mu=0 when the temperature is raised, will remain a crossover in the mu-region
where our Taylor expansion can be trusted. If this result, obtained on a coarse
lattice, is confirmed by simulations on finer lattices now in progress, then we
predict that no {\em chiral} critical point will be found for mu_B \lesssim 500
MeV, unless the phase diagram contains additional transitions.Comment: 4 pages, 6 figures, proceedings of Quark Matter 2008, Jaipur (India),
Feb. 2008, to appear in J. Phys.
Casimir scaling or flux counting?
Potentials between two static sources in various representations of the SU(3)
gauge group are determined on anisotropic 3+1 dimensional lattices. Strong
evidence in favour of "Casimir scaling" is found.Comment: 4 pages Latex, epscrc2.sty with 2 epsf figure
Phase diagram at finite temperature and quark density in the strong coupling limit of lattice QCD for color SU(3)
We study the phase diagram of quark matter at finite temperature (T) and
finite chemical potential (mu) in the strong coupling limit of lattice QCD for
color SU(3). We derive an analytical expression of the effective free energy as
a function of T and mu, including baryon effects. The finite temperature
effects are evaluated by integrating over the temporal link variable exactly in
the Polyakov gauge with anti-periodic boundary condition for fermions. The
obtained phase diagram shows the first order phase transition at low
temperatures and the second order phase transition at high temperatures
separated by the tri-critical point in the chiral limit. Baryon has effects to
reduce the effective free energy and to extend the hadron phase to a larger mu
direction at low temperatures.Comment: 18 pages, 10 figure
Heavy Quark Free Energies and Screening in SU(2) Gauge Theory
We investigate the singlet, triplet and colour average heavy quark free
energies in SU(2) pure gauge theory at various temperatures T. We focus on the
long distance behaviour of the free energies, studying in particular the
temperature dependence of the string tension and the screening masses. The
results are qualitatively similar to the SU(3) scenario, except near the
critical temperature Tc of the deconfining transition. Finally we test a
recently proposed method to renormalize the Polyakov loop.Comment: 5 pages, 4 figures, contribution to the Proceedings of SEWM 2002
(Heidelberg
String Breaking and Quarkonium Dissociation at Finite Temperatures
Recent lattice studies of string breaking in QCD with dynamical quarks
determine the in-medium temperature dependence of the heavy quark potential.
Comparing this to the binding energies of different quarkonium states, we check
if these can decay into open charm/beauty in a confined hadronic medium. Our
studies indicate in particular that the chi_c and the psi dissociate into open
charm below the deconfinement point.Comment: 8 pages LaTeX, 4 figure
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