Electromagnetic radiation from excited hadronic matter is one of the best ways to study the properties of matter. Considering various processes in the hadronic gas, Kapusta, Lichard, and Seibert have found a n p + x y reaction with an intermediate virtual x or p to be the main source of photons with energy greater than 0.7 GeV. However, at temperatures considered, T = 100-200MeV, a n p pair can easily form an Al(1260) resonance, and we show that this mechanism leads to photon production rates exceeding those suggested previously.PACS number(s): 12.38. Mh, 13.85.Qk, 21.65.+f, 25.75.+r

No abstract

Perturbative analysis of parton kinetics for high energy nuclear collisions shows that thermal equilibration of gluons happens very fast, while quark production is much slower. A simple "minimal model" is proposed which includes only incoming quarks and antiquarks. We have found that a smaller quark number is more than compensated by the fact that they are imbedded into the hotter glue. Predicted yield of dileptons and photons in the interesting kinematic region are larger than considered before, and are quite observable at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider. PACS numbers: 25.75.+r, 12.38.Mh, 24.85.+p The main objective of the future experimental heavyion program at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) is the production and studies of a new form of matter, the so-called quark-gluon plasma (QGP) [1], which is expected to exist during the first few fm/c of the collisions. Extrapolations from lower energies are difficult, because for heavy ion collisions at RHIC and LHC energies one is entering a new dynamical regime, in which the so-called semihard processes, involving partons with momenta (and momenta transfer) p ~l-3 GeV, can no longer be considered as isolated rare events, but are involved in some complicated, cascade-type processes.Early discussions of parton kinetics taking place after the primary collisions can be found in [1], and that of "partonic saturation" effects occurring before the collision can be found in [2]. The role of few-GeV partons (known also as "mini-jets") in nuclear collisions was discussed in [3][4][5]. Among important recent developments are estimates of parton energy losses in QGP (see [6] and references therein), which for the gluons reach TgdE/dx «2-3 GeV/fm. Thus, contrary to some earlier claims, most of the mini-jets should be trapped in the fireball, created in central collisions, and therefore contribute to equilibration processes.One open question is whether the main amount of produced entropy is due to complicated partonic substructure of nuclei themselves, and this entropy is just "liberated" at the collision moment, or it is produced in a more conventional manner, due to rescattering and production processes after the primary collisions took place. Assuming that perturbative QCD and parton model to be applicable down to 1 GeV scale (x ~0.01, at RHIC), one may come to the former conclusion [5]. If gluonic structure functions are indeed so "dense," that one can speak about QGP as soon as partons are separated from each other after the first collision, at the time scale ^separation ~ 1/pt ~ 0.2 fm/c. Consequences of this (the most optimistic) scenario for dileptons were recently discussed in [7]; it leads to very high initial temperatures and very big yields. However, we do not think such a regime can be dynamically sustained (at least, not if one is using perturbative cross sections).The specific "hot-glue" scenario to be discussed below was recently suggested by one of us [8]. An amb...

We extend the normal transport model to include the medium effect on pions by treating them as quasiparticles. The property of the quasipion is determined using the delta-hole model. Modeling heavy-ion collisions at intermediate energies with the new transport equations, we find that it leads to an enhanced production of pions with low kinetic energies. This gives a plausible explanation for the observed enhancement of soft pions in the Bevalac experiments. PACS number(s): 25.75.+r

No abstract

No abstract

Hot gluons are the dominant components of the QCD plasma to be formed in future high energy heavy ion experiments. In this paper we study the elementary processes in the plasma medium for gluon multiplication based on all orders of the tree-diagrams in perturbative QCD. When applying to the chemical equilibration in the expanding system, we found that the gluons reaches chemical equilibrium well within its plasma phase. The inclusion of all the next-to-leading order processes makes the equilibration considerably faster than the simple gg ↔ ggg one considered previously.

On-body wireless networks (oBWNs) play a crucial role in improving the ubiquitous healthcare services. Using oBWNs, the vital physiological information of the patient can be gathered from the wearable sensor nodes and accessed by the authorized user like the health professional or the doctor. Since the open nature of wireless communication and the sensitivity of physiological information, secure communication has always been the vital issue in oBWNs-based systems. In recent years, several authentication schemes have been proposed for remote patient monitoring. However, most of these schemes are so susceptible to security threats and not suitable for practical use. Specifically, all these schemes using lightweight cryptographic primitives fail to provide forward secrecy and suffer from the desynchronization attack. To overcome the historical security problems, in this paper, we present a lightweight and secure three-factor authentication scheme for remote patient monitoring using oBWNs. The proposed scheme adopts one-time hash chain technique to ensure forward secrecy, and the pseudonym identity method is employed to provide user anonymity and resist against desynchronization attack. The formal and informal security analyses demonstrate that the proposed scheme not only overcomes the security weaknesses in previous schemes but also provides more excellent security and functional features. The comparisons with six state-of-the-art schemes indicate that the proposed scheme is practical with acceptable computational and communication efficiency.