Deconfinement in QCD with dynamical quarks

We study the phase structure of full QCD within the canonical ensemble with respect to triality in a lattice formulation. The procedure for the calculation of the effective potentials in this case is given. As an example we consider the three dimensional SU(2) gauge model at finite temperatures in the strong coupling region. The potential exhibits a deconfinement phase transition unlike the similar potential obtained in the grand canonical ensemble which demonstrates explicit Z(N) symmetry breaking at any temperature. Furthermore, we investigate the effective potential with the chiral condensate included. In contradiction to other authors, we find chiral symmetry restoration in all triality sectors. In the scheme with massless staggered fermions we observe chiral symmetry restoration accompanying a deconfinement phase transition of first order. Above the critical point, besides two Z(2) symmetric "deconfining" vacua there exists a metastable "confining" vacuum in a wide region of parameters. Such a picture could be interpreted as an indication on a mixed state of hadrons and quarks in the vicinity of the critical line.Comment: 17 pages with 6 eps. figures include

Thermalization of Hadrons via Hagedorn States

Hagedorn states are characterized by being very massive hadron-like resonances and by not being limited to quantum numbers of known hadrons. To generate such a zoo of different Hagedorn states, a covariantly formulated bootstrap equation is solved by ensuring energy conservation and conservation of baryon number $B$, strangeness $S$ and electric charge $Q$. The numerical solution of this equation provides Hagedorn spectra, which enable to obtain the decay width for Hagedorn states needed in cascading decay simulations. A single (heavy) Hagedorn state cascades by various two-body decay channels subsequently into final stable hadrons. All final hadronic observables like masses, spectral functions and decay branching ratios for hadronic feed down are taken from the hadronic transport model UrQMD. Strikingly, the final energy spectra of resulting hadrons are exponential showing a thermal-like distribution with the characteristic Hagedorn temperature

Progress on a canonical finite density algorithm

We test the finite density algorithm in the canonical ensemble which combines the HMC update with the accept/reject step according to the ratio of the fermion number projected determinant to the unprojected one as a way of avoiding the determinant fluctuation problem. We report our preliminary results on the Polyakov loop in different baryon number sectors which exhibit deconfinement transitions on small lattices. The largest density we obtain around $T_c$ is an order of magnitude larger than that of nuclear matter. From the conserved vector current, we calculate the quark number and verify that the mixing of different baryon sectors is small.Comment: 6 pages, 2 figures. Talk presented at Lattice 2004 conference. Lattice2004(non-zero

Fast Dynamical Evolution of Hadron Resonance Gas via Hagedorn States

Hagedorn states are the key to understand how all hadrons observed in high energy heavy ion collisions seem to reach thermal equilibrium so quickly. An assembly of Hagedorn states is formed in elementary hadronic or heavy ion collisions at hadronization. Microscopic simulations within the transport model UrQMD allow to study the time evolution of such a pure non-equilibrated Hagedorn state gas towards a thermally equilibrated Hadron Resonance Gas by using dynamics, which unlike strings, fully respect detailed balance. Propagation, repopulation, rescatterings and decays of Hagedorn states provide the yields of all hadrons up to a mass of m=2.5 GeV. Ratios of feed down corrected hadron multiplicities are compared to corresponding experimental data from the ALICE collaboration at LHC. The quick thermalization within t=1-2 fm\c of the emerging Hadron Resonance Gas exposes Hagedorn states as a tool to understand hadronization.Comment: 5 pages, 7 figures, 1 tabl

Charmonium Production from the Secondary Collisions at LHC Energy

We consider the charmonium production in thermalized hadronic medium created in ultrarelativistic heavy ion collisions at LHC energy. The calculations for the secondary $J/\psi$ and $\psi^,$ production by $D\bar D$ annihilation are performed within a kinetic model taking into account the space-time evolution of a longitudinally and transversely expanding medium. We show that the secondary charmonium production appears almost entirely during the mixed phase and it is very sensitive to the charmonium dissociation cross section with co-moving hadrons. Within the most likely scenario for the dissociation cross section of the $J/\psi$ mesons their regeneration in the hadronic medium will be negligible. The secondary production of $\psi^,$ mesons however, due to their large cross section above the threshold, can substantially exceed the primary yield.Comment: ps file 11

Интегрирование Украины в европейскую грид-инфраструктуру

Українські фахівці з грід-технологій розпочали реалізацію Української національної грід-ініціативи (УНГІ), що входить до головних діючих європейських проектів EGEE та EGI. Обґрунтовано перспективність і необхідність участі в провідних світових наукових проектах. Розглядаються загальні риси і властивості УНГІ та європейських грід-структур і проектів, акцентується увага на можливості вирішувати прикладні грід-задачі у рамках УНГІ. Представлено сучасний стан УНГІ, її обчислювальний і кадровий потенціал. Описуються проблеми і перспективи розвитку УНГІ, а також шляхи і способи міжнародної кооперації.Ukrainian Grid community has established Ukrainian National Grid Initiative (UNGI) which has joined up the major active European projects EGEE and EGI. The community of objectives based on the involvement in world leading scientific projects is elucidated. General features of UNGI and European Grid structures and projects together with various Grid-based applications supported by UNGI are discussed. Current UNGI activities and its future plans in view of realistic computational and human resources are described. The problems and prospects of rapidly progressing Ukrainian Grid infrastructure on the way of international cooperation and integration are illuminated.Украинские специалисты в области грид-технологий начали реализацию Украинской национальной грид-инициативы (УНГИ), которая входит в главные действующие европейские проекты EGEE и EGI. Обоснована перспективность и необходимость участия в ведущих мировых научных проектах. Рассматриваются общие черты и характеристики УНГИ, а также европейских грид-структур и проектов, акцентируется внимание на возможности решения прикладных грид-задач в рамках УНГИ. Представляются современное состояние УНГИ, ее вычислительный и кадровый потенциал. Описываются проблемы и перспективы развития УНГИ, а также пути и способы международной кооперации