1,767 research outputs found
Thermalization through Hagedorn states - the importance of multiparticle collisions
Quick chemical equilibration times of hadrons within a hadron gas are
explained dynamically using Hagedorn states, which drive particles into
equilibrium close to the critical temperature. Within this scheme master
equations are employed for the chemical equilibration of various hadronic
particles like (strange) baryon and antibaryons. A comparison of the Hagedorn
model to recent lattice results is made and it is found that for both Tc =176
MeV and Tc=196 MeV, the hadrons can reach chemical equilibrium almost
immediately, well before the chemical freeze-out temperatures found in thermal
fits for a hadron gas without Hagedorn states.Comment: 8 pages, 3 figures, talk presented at the International Conference on
Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, Sept. 27 - Oct.
2, 200
Aspectos biológicos de Brevipalpus obovatus Donnadieu (Acari: Tenuipalpidae) em maracujazeiro.
Considerando a ocorrência do ácaro Brevipalpus obovatus (Donnadieu, 1875) (Acari, Tenuipalpidae) em cultivos de maracujazeiro (Passiflora edulis Sims f. flavicarpa Deg. - Passifloraceae) no Estado da Bahia, a biologia dessa espécie foi estudada para avaliar o desenvolvimento e a reprodução em folhas de maracujá amarelo. O estudo foi conduzido em laboratório a 25 ± 1° C, 70 ± 10% de umidade relativa e 12 horas de fotofase. O período de ovo a adulto foi de 19,11 ± 0,16 dias, com sobrevivência de 86,11%. A longevidade média das fêmeas foi de 37,69 ± 3,06 dias e a oviposição média diária de 1,29 ± 0,05 ovos/fêmea. A razão intrínseca de aumento (rm) foi de 0,064, a razão finita de aumento (λ) de 1,066 fêmeas/fêmea/dia, a duração média de uma geração (T) de 38,94 dias e a taxa líquida de reprodução (Ro) de 12,13. Os resultados indicam que o maracujazeiro amarelo é um hospedeiro favorável ao desenvolvimento e reprodução de B. obovatus
Particle Ratios and the QCD Critical Temperature
We show how the measured particle ratios at RHIC can be used to provide
non-trivial information about the critical temperature of the QCD phase
transition. This is obtained by including the effects of highly massive
Hagedorn resonances on statistical models, which are used to describe hadronic
yields. Hagedorn states are relevant close to and have been shown to
decrease to the KSS limit and allow for quick chemical equilibrium
times in dynamical calculations of hadrons. The inclusion of Hagedorn states
creates a dependence of the thermal fits on the Hagedorn temperature, ,
which is assumed to be equal to , and leads to an overall improvement of
thermal fits. We find that for Au+Au collisions at RHIC at
GeV the best square fit measure, , occurs at MeV and
produces a chemical freeze-out temperature of 170.4 MeV and a baryon chemical
potential of 27.8 MeV.Comment: 6 pages, 2 figures, talk presented at the International Conference on
Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, Sept. 27 - oct.
2, 200
Jet Quenching in Non-Conformal Holography
We use our non-conformal holographic bottom-up model for QCD described in
1012.0116 to further study the effect of the QCD trace anomaly on the energy
loss of both light and heavy quarks in a strongly coupled plasma. We compute
the nuclear modification factor for bottom and charm quarks in an
expanding plasma with Glauber initial conditions. We find that the maximum
stopping distance of light quarks in a non-conformal plasma scales with the
energy with a temperature (and energy) dependent effective power.Comment: 4 pages, 1 figure. Proceedings for Quark Matter 201
Fast Equilibration of Hadrons in an Expanding Fireball
Due to long chemical equilibration times within standard hadronic reactions
during the hadron gas phase in relativistic heavy ion collisions it has been
suggested that the hadrons are "born" into equilibrium after the quark gluon
plasma phase. Here we develop a dynamical scheme in which possible Hagedorn
states contribute to fast chemical equilibration times of baryon anti-baryon
pairs (as well as kaon anti-kaon pairs) inside a hadron gas and just below the
critical temperature. Within this scheme, we use master equations and derive
various analytical estimates for the chemical equilibration times. Applying a
Bjorken picture to the expanding fireball, the kaons and baryons as well as the
bath of pions and Hagedorn resonances can indeed quickly chemically equilibrate
for both an initial overpopulation or underpopulation of Hagedorn resonances.
Moreover, a comparison of our results to and
ratios at RHIC, indeed, shows a close match.Comment: 4 pages, 5 figure
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