1,040 research outputs found
Dissociation of hadrons in quark matter within finite temperature field theory approach on the light front
We present a relativistic three-body equation to investigate the properties
of nucleons in hot and dense nuclear/quark matter. Within the light front
approach we utilize a zero-range interaction to study the three-body dynamics.
The relativistic in-medium equation is derived within a systematic Dyson
equation approach that includes the dominant medium effects due to Pauli
blocking and self energy corrections. We present the in-medium nucleon mass and
calculate the dissociation of the three-body system.Comment: 4 pages, 2 figures. Presented by S. Mattiello at Light-Cone 2004,
Amsterdam, 16 - 20 Augus
Restoration of chiral symmetry in light-front finite temperature field theory
We investigate the properties of and states in hot and dense
quark matter in the framework of light-front finite temperature field theory.
Presently we use the Nambu Jona-Lasinio model of QCD and derive the gap
equation at finite temperature and density. We study pionic and scalar diquark
dynamics in quark matter and calculate the masses and the Mott dissociation as
a function of the temperature and the chemical potential . For the
scalar diquark we determine the critical temperature of color
superconductivity.Comment: 4 pages, 3 figures, Presented by S.Strau\ss at Light-Cone 2004,
Amsterdam, 16 - 20 Augus
Light front field theory of relativistic quark matter
Light-front quantization to many-particle systems of finite temperature and
density provides a novel approach towards a relativistic description of quark
matter and allows us to calculate the perturbative as well as the
non-perturbative regime of QCD. Utilizing a Dyson expansion of light-front
many-body Green functions we have so far calculated three-quark, quark-quark,
and quark-antiquark correlations that lead to the chiral phase transition, the
formation of hadrons and color superconductivity in a hot and/or dense
environment. Presently, we use an effective zero-range interaction, to compare
our results with the more traditional instant form approach where applicable.Comment: contribution to Quark Matter 2005, 18th International Conference on
Nucleus Nucleus Colisions, 4 pages, 2 figures, hiph-preprint.sty file neede
Correlations in hot and dense quark matter
We present a relativistic three-body equation to investigate three-quark
clusters in hot and dense quark matter. To derive such an equation we use the
Dyson equation approach. The equation systematically includes the Pauli
blocking factors as well as the self energy corrections of quarks. Special
relativity is realized through the light front form. Presently we use a
zero-range force and investigate the Mott transition.Comment: 6 pages, 4 figure, Few-Body Systems style file
Dynamics of few-body states in a medium
Strongly interacting matter such as nuclear or quark matter leads to few-body
bound states and correlations of the constituents. As a consequence quantum
chromodynamics has a rich phase structure with spontaneous symmetry breaking,
superconductivity, condensates of different kinds. All this appears in many
astrophysical scenarios. Among them is the formation of hadrns during the early
stage of the Universe, the structure of a neutron star, the formation of nuclei
during a supernova explosion. Some of these extreme conditions can be simulated
in heavy ion colliders. To treat such a hot and dense system we use the Green
function formalism of many-body theory. It turns out that a systematic Dyson
expansion of the Green functions leads to modified few-body equations that are
capable to describe phase transitions, condensates, cluster formation and more.
These equations include self energy corrections and Pauli blocking. We apply
this method to nonrelativistic and relativistic matter. The latter one is
treated on the light front. Because of the medium and the inevitable truncation
of space, the few-body dynamics and states depend on the thermodynamic
parameters of the medium.Comment: 3 pages, 2 figures, talk presented at the 19th European Conference on
Few-Body System
Thermoregulation of alpacas bred in Italy
The present study monitored daily and seasonal variations of rectal temperature in response to different environmental temperatures in alpacas bred in the Italian Apennines at 300 m a. s. l. In each season, the rectal temperature of 33 clinically healthy alpacas was measured three times/day (morning, midday, afternoon). Ambient temperatures were also recorded. Rectal temperatures ranged from a minimum value of 35.1 to a maximum of 39.4\ub0C, with a maximum daily thermal excursion (\u394Trec) of 3.2\ub0C. Temperatures increased throughout the day, with highly significant differences recorded in both young and adult animals between all the time bands (P<0.001). These differences were particularly dramatic for adults in summer, when the mean rectal temperature in the morning was 36.3\ub10.13\ub0C, probably as a consequence of recent shearing. Significant \u394Trec differences were recorded depending on the season in both young and adult animals (P<0.001), with the highest \u394Trec values recorded in summer (although the highest daily ambient excursion value was recorded in winter). In conclusion, similarly to alpacas bred in their natural environment, alpacas bred in Italy show a wide thermal neutrality zone, which is probably an adaptive response, that allows the animals to save energy. In the Italian Apennines, in order to prevent situations of hypothermia, with possible detrimental effects on alpacas' health and welfare, shearing should be carried out only in warm seasons
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