382 research outputs found
QCD Critical Region and Quark Gluon Plasma from an Imaginary mu_B
We discuss the imaginary chemical potential approach to the study of QCD at
nonzero temperature and density, present results for the four flavor model in
the different phases and show that this method is ideally suited for a
comparison between lattice data and phenomenological models.Comment: 3 pages, Lattice2003(nonzero); references adde
QCD thermodynamics from an imaginary mu_B: results on the four flavor lattice model
We study four flavor QCD at nonzero temperature and density by analytic
continuation from an imaginary chemical potential. The explored region is T =
0.95 T_c < T < 3.5 T_c, and the baryochemical potentials range from 0 to
approx. 500 MeV. Observables include the number density, the order parameter
for chiral symmetry, and the pressure, which is calculated via an integral
method at fixed temperature and quark mass. The simulations are carried out on
a 16^3 X 4 lattice, and the mass dependence of the results is estimated by
exploiting the Maxwell relations. In the hadronic region we confirm that the
results are consistent with a simple resonance hadron gas model, and we
estimate the critical density by combining the results for the number density
with those for the critical line. In the hot phase, above the endpoint of the
Roberge-Weiss transition T_E approx 1.1 T_c the results are consistent with a
free lattice model with a fixed effective number of flavor slightly different
from four. We confirm that confinement and chiral symmetry are coincident by a
further analysis of the critical line, and we discuss the interrelation between
thermodynamics and critical behavior. We comment on the strength and weakness
of the method, and propose further developments.Comment: 20 pages, 13 figures; comments and references adde
Study of finite temperature QCD with 2+1 flavors via Taylor expansion and imaginary chemical potential
We study QCD with 2+1 flavors at nonzero temperature and nonzero chemical
potential. We present preliminary results obtained from lattice calculations
performed with an improved staggered fermions action (p4-action) on lattice
with temporal extent N_t = 4 on a line of constant physics with the strange
quark mass adjusted to its physical value and a pion mass of about 220 MeV. We
compute at imaginary chemical potential and compare with Taylor expansion
results. We focus our study on a range of temperatures 0.94 < T/T_c < 1.08.Comment: 7 pages, 12 figures, talk presented at the XXVIII International
Symposium on Lattice Field Theory (Lattice 2010), June 14-19, 2010,
Villasimius, Sardinia, Ital
QCD at High Temperature : Results from Lattice Simulations with an Imaginary mu
We summarize our results on the phase diagram of QCD with emphasis on the
high temperature regime. For the results are compatible with a
free field behavior, while for this is not the case, clearly
exposing the strongly interacting nature of QCD in this regionComment: 7 pages, 2 figures; To appear in the proceedings of QCD@Work
2005,International Workshop on Quantum Chromodynamics, Conversano, Bari,
Italy, 16-20 Jun 200
CAN GENDER QUOTAS BREAK DOWN NEGATIVE STEREOTYPES? EVIDENCE FROM CHANGES IN ELECTORAL RULES
In this paper we analyse the effect of gender quotas on women involvement in political activity using a rich data set providing information on all Italian local administrators elected from 1985 to 2007. Gender quotas were introduced in Italy by law in 1993 and were in force until 1995. Because of the short period covered by the reform, some municipalities never voted under the gender quota regime. This allows us to individuate a treatment and a control group and to estimate the effects of gender quotas using a difference-in-differences estimation strategy. Our estimates show that women representation in politics after the reform has increased significantly more in municipalities that were interested by the reform compared to municipalities that were not affected. This result holds true also if we exclude from our analysis elections taking place during the period in which the reform was in force. Moreover, the higher women representation in âGender Quota Municipalitiesâ is not related to the advantages that women elected during the reform have obtained from incumbency and does not seem to be driven by different temporal trends among Southern and Northern regions. These findings suggest that affirmative actions are useful to break down stereotypes against women.Affirmative Actions, Gender Quotas, Discrimination, Stereotypes, Politicians, Natural Experiment
High Temperature QCD
Comment: 22 pages, 26 figures; plenary talk at Lattice 2013, Cairns, QLD, Australia, June 24--29 2012; references added, typos correcte
Finite density (might well be easier) at finite temperature
Experiments with imaginary chemical potential and Glasgow method carried out
in two interrelated models - four dimensional QCD in the infinite coupling
limit, and one dimensional QCD - support the point of view expressed by the
title.Comment: LATTICE99(finite) 3 pages, 4 figure
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