118886830
Thermodynamics inducing massive particles’ tunneling and cosmic censorship
By calculating the change of entropy, we prove that the first law of black hole thermodynamics leads to the tunneling probability of massive particles through the horizon, including the tunneling probability of massive charged particles from the Reissner–Nordström black hole and the Kerr–Newman black hole. Novelly, we find the trajectories of massive particles are close to that of massless particles near the horizon, although the trajectories of massive charged particles may be affected by electromagnetic forces. We show that Hawking radiation as massive particles tunneling does not lead to violation of the weak cosmic-censorship conjecture.
118653526
On the Hamiltonian form of 3D massive gravity
We present a Chern-Simons-like action for the general massive gravity model propagating two spin-2 modes with independent masses in three spacetime dimensions (3D), and we use it to find a simple Hamiltonian form of this model. The number of local degrees of freedom, determined by the dimension of the physical phase space, agrees with a linearized analysis except in some limits, in particular that yielding topologically new massive gravity, which therefore suffers from a linearization instability.
118358667
Hawking radiation as tunneling derived from black hole thermodynamics through the quantum horizon
We show that the first law of the black hole thermodynamics can lead to the tunneling probability through the quantum horizon by calculating the change of entropy with the quantum gravity correction and the change of surface gravity is presented clearly in the calculation. The method is also applicable to the general situation which is independent on the form of black hole entropy and this verifies the connection of black hole tunneling with thermodynamics further. In the end we discuss the crucial role of the relation between the radiation temperature and surface gravity in this derivation. (C) 2008 Elsevier B.V. All rights reserved.
118352477
Noncommutative information is revealed from Hawking radiation as tunneling
We revisit the tunneling process from a Schwarzschild black hole in the noncommutative spacetime and obtain the nonthermal tunneling probability. In such nonthermal spectrum, the correlations are discovered, which can carry the information about the noncommutativity. Thus this enlightens a way to find the noncommutative information in the Hawking radiation. The entropy is also shown to be conserved in the whole radiation process, which implies that the unitarity is held even for the Hawking radiation from noncommutative black holes.
119185446
Hidden messenger revealed in Hawking radiation: A resolution to the paradox of black hole information loss
Using standard statistical method, we discover the existence of correlations among Hawking radiations (of tunneled particles) from a black hole. The information carried by such correlations is quantified by mutual information between sequential emissions. Through a careful counting of the entropy taken out by the emitted particles, we show that the black hole radiation as tunneling is an entropy conservation process. While information is leaked out through the radiation, the total entropy is conserved. Thus, we conclude the black hole evaporation process is unitary. (C) 2009 Elsevier B.V. All rights reserved.
118770480
The temperature in Hawking radiation as tunneling
Abstract The quasi-classical method of deriving Hawking radiation under the consideration of canonical invariance is investigated. We find that the horizon should be regarded as a two-way barrier and the ingoing amplitude should be calculated according to the negative energy particles tunneling into the black hole because of the whole space–time interchange and thus the standard Hawking temperature is recovered. We also discuss the advantage of the Painleve coordinates in Hawking radiation as tunneling.
119375105
Multiple parton scattering in nuclei: beyond helicity amplitude approximation
Multiple parton scattering and induced parton energy loss in deeply inelastic scattering (DIS) off heavy nuclei is studied within the framework of generalized factorization in perturbative QCD with a complete calculation beyond the helicity amplitude (or soft bremsstrahlung) approximation. Such a calculation gives rise to new corrections to the modified quark fragmentation functions. The effective parton energy loss is found to be reduced by a factor of 5/6 from the result of helicity amplitude approximation.
14083408
Direct photon production of d+A and A+A collisions at RHIC
Direct photon productions in minimum bias d+Cu and d+Au and central Cu+Cu and Au+Au at center of mass energies {radical}s = 62.4 GeV and 200GeV at RHIC are investigated systematically by taking into account jet quenching effect, medium-induced photon bremsstrahlung and jet-photon conversion in the hot QGP as well as known cold nuclear matter effects such as the isospin effect, the Cronin effect, shadowing effect, EMC effect and cold nuclear matter energy loss. It is shown that at high p{sub T} the nuclear modification factor for direct photon R{sub AA}(p{sub T}) is suppressed and dominated by cold nuclear matter effects, and there is no large enhancement due to medium-induced photon bremsstrahlung and jet-photon conversion in the hot QGP. Comparison of numerical simulations with experimental data rules out large Cronin enhancement and incoherent photon emission in medium, though large error bars in currently experimental data can not provide tight constraints on other nuclear matter effects.
117428082
The Physics of $Z^0/\gamma^*$-tagged jets at the LHC
Electroweak bosons produced in conjunction with jets in high-energy collider experiments is one of the principle final-state channels that can be used to test the accuracy of perturbative Quantum Chromodynamics calculations and to assess the potential to uncover new physics through comparison between data and theory. In this paper we present results for the $Z^0/\gamma^*$+jet production cross sections at the LHC at leading and next-to-leading orders. In proton-proton reactions we elucidate up to ${\cal O}(G_F\alpha_s^2)$ the constraints that jet tagging via the $Z^0/\gamma^*$ decay dileptons provides on the momentum distribution of jets. In nucleus-nucleus reactions we demonstrate that tagged jets can probe important aspects of the dynamics of quark and gluon propagation in hot and dense nuclear matter and characterize the properties of the medium-induced parton showers in ways not possible with more inclusive measurements. Finally, we present specific predictions for the anticipated suppression of the $Z^0/\gamma^*$+jet production cross section in the quark-gluon plasma that is expected to be created in central lead-lead collisions at the LHC relative to the naive superposition of independent nucleon-nucleon scatterings.
118566042
A possible determination of the quark radiation length in cold nuclear matter
Abstract We calculate the differential Drell–Yan production cross section in proton–nucleus collisions by including both next-to-leading order perturbative effects and effects of the nuclear medium. We demonstrate that dilepton production in fixed target experiments is an excellent tool to study initial-state parton energy loss in large nuclei and to accurately determine the stopping power of cold nuclear matter. We provide theoretical predictions for the attenuation of the Drell–Yan cross section at large values of Feynman x F and show that for low proton beam energies experimental measurements at Fermilabʼs E906 can clearly distinguish between nuclear shadowing and energy loss effects. If confirmed by data, our results may help determine the quark radiation length in cold nuclear matter X 0 ∼ 10 − 13 m .
15237897
JET QUENCHING OF MASSIVE QUARKS IN A NUCLEAR MEDIUM
Utilizing the generalized factorization of twist-4 processes, we derive the modified heavy quark fragmentation function after considering the gluon radiation induced by multiple scattering in DIS. It is found that the mass eects of heavy quark may reduce the gluon formation time and change the medium size dependence of heavy quark energy loss. The radiative energy loss is also significantly suppressed relative to a light quark due to the dead-cone eect. In relativistic heavy-ion collisions, when a fast parton propagating in a dense medium, it may experience multiple scattering with other partons in nucleus and lose a large amount of energy loss via induced gluon radiation 1 . Such kind of jet quenching phe