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

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

High Temperature QCD

Comment: 22 pages, 26 figures; plenary talk at Lattice 2013, Cairns, QLD, Australia, June 24--29 2012; references added, typos correcte

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 $T \ge 1.5 T_c$ the results are compatible with a free field behavior, while for $T \simeq 1.1 T_c$ 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 “Gender Quota Municipalities” 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

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