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 $r_{\rm b} m_G\approx13.6$. 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 ‘practice-led research’, which is a method off the beaten track in media production studies. We examine assignments by students from the educational program of ‘Screenplay Development’ 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 Schön’s (2013) practice epistemology. As our analytical lens we use Robin Nelson’s (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 you’re 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