Vacuum fluctuations and the thermodynamics of chiral models

We consider the thermodynamics of chiral models in the mean-field approximation and discuss the relevance of the (frequently omitted) fermion vacuum loop. Within the chiral quark-meson model and its Polyakov loop extended version, we show that the fermion vacuum fluctuations can change the order of the phase transition in the chiral limit and strongly influence physical observables. We compute the temperature-dependent effective potential and baryon number susceptibilities in these models, with and without the vacuum term, and explore the cutoff and the pion mass dependence of the susceptibilities. Finally, in the renormalized model the divergent vacuum contribution is removed using the dimensional regularization.Comment: 9 pages, 5 figure

Thermodynamics of (2+1)-flavor QCD: Confronting Models with Lattice Studies

The Polyakov-quark-meson (PQM) model, which combines chiral as well as deconfinement aspects of strongly interacting matter is introduced for three light quark flavors. An analysis of the chiral and deconfinement phase transition of the model and its thermodynamics at finite temperatures is given. Three different forms of the effective Polyakov loop potential are considered. The findings of the (2+1)-flavor model investigations are confronted to corresponding recent QCD lattice simulations of the RBC-Bielefeld, HotQCD and Wuppertal-Budapest collaborations. The influence of the heavier quark masses, which are used in the lattice calculations, is taken into account. In the transition region the bulk thermodynamics of the PQM model agrees well with the lattice data.Comment: 13 pages, 7 figures, 3 tables; minor changes, final version to appear in Phys. Rev.

Finite-Temperature Gluon Condensate with Renormalization Group Flow Equations

Within a self-consistent proper-time Renormalization Group (RG) approach we investigate an effective QCD trace anomaly realization with dilatons and determine the finite-temperature behavior of the gluon condensate. Fixing the effective model at vanishing temperature to the glueball mass and the bag constant a possible gluonic phase transition is explored in detail. Within the RG framework the full non-truncated dilaton potential analysis is compared with a truncated potential version.Comment: 22 pages, 11 figures, LaTeX2e; revised version accepted for publication in Phys. Rev.

Studies of the sexual development and spawning of yellowfin tuna, Neothunnus macropterus, and skipjack, Katsuwonus pelamis, in three areas of the Eastern Pacific Ocean, by examination of gonads.

ENGLISH: Knowledge of the size and age at maturity, spawning seasons, and spawning areas of the tropical tunas supporting the fishery in the Eastern Pacific is an important part of the basic information required for understanding their life history, population structure, and fishery dynamics. Until a few years ago nothing was known of these matters. In 1947 the senior author and one of his colleagues (Schaefer and Marr 1948, Schaefer 1948) were able to demonstrate that both yellowfin tuna and skipjack spawn offshore from Central America at least during the late winter and spring months. During January to April many yellowfin tuna over about 70 cm. total length in commercial catches from that region were found to have gonads in advanced stages of maturity, and specimens caught during late June were found to be spent. Maturing skipjack were collected in late February, and spawned-out fish were observed in late March. Numerous very young juveniles of the yellowfin, down to 10 mm. in length, and two very young juvenile skipjack, were captured in this area between January and May. SPANISH: El conocimiento del tamaño y la edad que corresponden a la primera madurez sexual, así como de las estaciones y áreas de desove de los atunes tropicales que mantienen las pesquerías del Pacífico Oriental, constituyen parte importante de la información que es menester para comprender la historia natural, la estructura de la población y la dinámica de la pesquería. Hasta hace pocos años nada se sabía sobre el particular. En 1947 el autor principal y uno de sus colegas (Schaefer y Marr, 1948; Schaefer, 1948) pudieron demostrar que tanto el atún aleta amarilla como el barrilete desovan en el mar abierto, frente a América Central, por lo menos durante la última parte del invierno y en la primavera. De enero a abril encontraron que muchos de los atunes aleta amarilla de más de 70 cm. de longitud total, procedentes de las pescas comerciales de dicha región; tenían gónadas en avanzados estados de madurez, mientras que ejemplares pescados hacia fines de junio ya habían desovado. Se recolectaron barriletes en vías de maduración a fines de febrero, al paso que en los últimos días de marzo se encontraron especímenes que ya habían desovado. Numerosos ejemplares muy juveniles del atún aleta amarilla, tan pequeños como 10 mm., y dos barriletes también muy juveniles, fueron pescados en esta región entre enero y mayo. (PDF contains 65 pages.

Fluctuations and the QCD phase diagram

In this contribution the role of quantum fluctuations for the QCD phase diagram is discussed. This concerns in particular the importance of the matter back-reaction to the gluonic sector. The impact of these fluctuations on the location of the confinement/deconfinement and the chiral transition lines as well as their interrelation are investigated. Consequences of our findings for the size of a possible quarkyonic phase and location of a critical endpoint in the phase diagram are drawn.Comment: 7 pages, 3 figures, to appear in Physics of Atomic Nucle

Center phase transition from matter propagators in (scalar) QCD

Novel order parameters for the confinement-deconfinement phase transition of quenched QCD and fundamentally charged scalar QCD are presented. Similar to the well-known dual condensate, they are defined via generalized matter propagators with $U(1)$-valued boundary conditions. The order parameters are easily accessible with functional methods. Their validity and accessibility is explicitly demonstrated by numerical studies of the Dyson-Schwinger equations for the matter propagators. Even in the case of heavy scalar matter, where the propagator does not show a signature of the phase transition, a discontinuity due to the transition can be extracted in the order parameters, establishing also fundamentally charged scalar matter as a probe for color confinement.Comment: accepted versio

QCD critical region and higher moments for three flavor models

One of the distinctive feature of the QCD phase diagram is the possible emergence of a critical endpoint. The critical region around the critical point and the path dependency of the critical exponents is investigated within effective chiral (2+1)-flavor models with and without Polyakov-loops. Results obtained in no-sea mean-field approximations where a divergent vacuum part in the fermion-loop contribution is neglected, are confronted to the renormalized ones. Furthermore, the modifications caused by the back-reaction of the matter fluctuations on the pure Yang-Mills system are discussed. Higher order, non-Gaussian moments of event-by-event distributions of various particle multiplicities are enhanced near the critical point and could serve as a probe to determine its location in the phase diagram. By means of a novel derivative technique higher order generalized quark-number susceptibilities are calculated and their sign structure in the phase diagram is analyzed.Comment: 12 pages, 11 figures. Final PRD version (references and one more equation added