Some considerations about NS5 and LST Hawking radiation

We have studied the Hawking radiation corresponding to the NS5 and Little String Theory (LST) black hole models using two semi-classical methods: the complex path method and a gravitational anomaly. After summarizing some known concepts about the thermodynamics of these theories, we have computed the emission rates for the two black hole models. The temperature calculated from, e.g. the well-known surface gravity expression, is shown to be identical to that obtained from both the computation of the gravitational anomaly and the complex path method. Moreover, the two semi-classical methods show that NS5 exhibits non-thermal behavior that contrasts with the thermal behavior of LST. We remark that energy conservation is the key factor leading to a non-thermal profile for NS5. In contrast, LST keeps a thermal profile even when energy conservation is considered because temperature in this model does not depend on energy.     

Hawking radiation As tunneling

We present a short and direct derivation of Hawking radiation as a tunneling process, based on particles in a dynamical geometry. The imaginary part of the action for the classically forbidden process is related to the Boltzmann factor for emission at the Hawking temperature. Because the derivation respects conservation laws, the exact spectrum is not precisely thermal. We compare and contrast the problem of spontaneous emission of charged particles from a charged conductor.     

Theoretical study of enhancement and suppression of the fluorescent spectra of dye molecules in a photonic crystal with a pseudogap

We have investigated the analytical forms of the photonic density of states (DOS) in a photonic crystal in the interested frequency regime according to the rule of state conservation in a photonic crystal with pseudogaps, which states that, if a valley of the DOS appears in some range of frequencies, it must be compensated for by increasing over some other ranges. By using a model DOS with a state-conservative photonic pseudogap, we have also investigated the enhancement and suppression of spontaneous emission of two-level atoms with different frequency positions and widths of emission spectra in a state-conservative electromagnetic reservoir; and the DOS-induced suppression, enhancement, narrowing and redshifting or blueshifting of spontaneous emission spectra are naturally obtained.     

Particle tunnels across the horizon of Garfinkle-Horowitz-Strominger dilaton black hole

We promote the work of Parikh and Wilczek on the black hole radiation to the emission of massive and charged particles from Garfinkle-Horowitz-Strominger black hole. The energy and charge of the space-time are conservational during the course of the evaporation. The calculation shows that the emission spectrum is not precisely thermal, while has a correction, and the conclusion supports the viewpoint of information conservation.     

Influence des conditions d'émission sur un écoulement de type jet plan laminaire isotherme ou chauffé

We propose numerical solutions for a laminar jet, accounting for emission conditions at the exit of the nozzle. Two emission cases are considered in this study: velocity and temperature profiles are uniform or parabolic, respectively. A finite difference scheme is developed for the resolution of the equations governing the isothermal and non-isothermal free jet and wall jet developing tangentially along an adiabatic flat plate. The analysed results are the centerline velocity and centerline temperature for the free jet, and wall temperature and shear stress for the wall jet. The results obtained are compared to another method that is based on two constraints of integration, i) conservation of momentum and ii) conservation of energy, to replace the emission conditions at the exit of the nozzle for the resolution of equations. Our results of the velocity and temperature profiles compare well with those obtained by the latter method solely in the plume region, where buoyancy forces are responsible for flow.     

Charged Particles’ Tunneling from Hot-NUT-Kerr-Newman-Kasuya Spacetime

We study the Hawking radiation as charged particles’ tunneling across the horizons of the Hot-NUT-Kerr-Newman-Kasuya spacetime by considering the spacetime background as dynamical and incorporating the self-gravitation effect of the emitted particles when the energy conservation, the angular momentum conservation, and the electric charge conservation are taken into account. Our result shows that the tunneling rate is related to the change of Bekenstein-Hawking entropy and the radiant spectrum is not pure thermal, but is consistent with an underlying unitary theory. The emission process is a reversible one, and the information is preserved as a natural result of the first law of black hole thermodynamics. To my teacher late Prof. Mainuddin Ahmed.     

Tunneling Radiation of Charged and Magnetized Particles from the Reissner-Nordstr?m-de Sitter Black Holes with Magnetic Charges

We extended the Parikh-Wilczek’s method to calculate the tunneling radiation of charged and magnetized particles from the event horizon and the cosmological horizon of the Reissner-Nordstr?m-de Sitter black hole with magnetic charges. We reconstructed the electromagnetic field tensor and recalculated the Lagrangian of the field corresponding to the source with electric and magnetic charges. By viewing the eclectic and magnetic charges as an equivalent electric charge, we obtained the tunneling rate of the charged and magnetized particles. Our calculation supports the conclusion given by Parikh and Wilczek that the emission spectrum is no longer purely thermal, and the emission process supports the information conservation.     

An angle-resolved photoemission study of the chemisorption of chalcogens on Cu(100) III. Cu(100) + p(2 x 2)S

Normal emission ARPES data for Cu(100) with a p(2x2)S overlayer were obtained in the photon energy range hv=11 to 34 eV. These spectra have been compared, within a framework proposed previously, with spectra from clean Cu(100). Changes were found in the Cu emission features, which could be explained by the relaxation of momentum conservation perpendicular to the surface in the optical excitation step and by the relaxation of momentum conservation parallel to the surface in the escape step. These changes include a broadening of the d-band peak and the strong attenuation of the sp-band peak. In addition, a prominent feature appears at about ?4.0 eV at normal emission upon sulfur chemisorption. We tentatively attribute its appearance at normal emission to a new surface umklapp process induced by the overlayer. Changes in the spectrum of scattered electrons were related to modifications of evanescent final states. The sulfur 3p_z^? and 3p_x.y-components could be separated at normal emission and are located at ?4.7 and ?5.4 eV, respectively. No dispersion of the sulfur 3p-bands was detected when the $\text{Γ}\text{X}$ and $\text{Γ}\text{M}$ symmetry lines of the surface Brillouin zone were probed. Sulfur-induced emission above the Cu d-bands was observed and attributed to antibonding states. This emission was directed towards the bulk [011] directions.     

Phonon-induced gaps in graphene and graphite observed by angle-resolved photoemission

Mapping by angle-resolved photoemission spectroscopy of the spectral functions of graphite and graphene layers at low temperatures reveals a heretofore unreported gap of ~ 67 meV at normal emission. This gap persists to room temperature and beyond, and diminishes for increasing emission angles. We show that this gap arises from electronic coupling to out-of-plane vibrational modes at the K(ˉ) point in the surface Brillouin zone in accordance with conservation laws and selection rules governed by quantum mechanics. Our study suggests a new approach for characterizing phonons and electron-phonon coupling in solids.     

TCP conservation in cosmology

We investigate decay processes in an expanding universe. The Born approximation conforms to one's expectations: emission of particles with energy conservation and subsequent cooling down. Interference graphs containing CP-violating effects are then investigated with an eye to discovering a violation of TCP. Such effects are found to be much smaller than what one might have thought, even for very rapid expansion and in the particular cosmology described by an asymptotic de Sitter space, TCP violations vanish identically.     

Quantum Tunneling Radiation of Kerr-NUT Black Hole

Based on particles in a dynamical geometry, extending the Parikh ＇s method of quantum tunneling, radiation, we deeply investigate the quantum tunneling radiation of Kerr-NUT bhck hole. When self-gravitating action, energy conservation, and angular momentum conservation are taken into account, the emission rate of the particle on the event horizon is related to the change of Bekenstein-Hawking entropy and the emission spectrum is not precisely thermal, but is consistent with an underlying unitary theory.     

Viscous brane cosmology with a brane-bulk energy interchange term

We assume a flat brane located at y = 0, surrounded by an AdS space, and consider the 5D Einstein equations when the energy flux component of the energy-momentum tensor is related to the Hubble parameter through a constant Q. We calculate the metric tensor, as well as the Hubble parameter on the brane, when Q is small. As a special case, if the brane is tensionless, the influence from Q on the Hubble parameter is absent. We also consider the emission of gravitons from the brane, by means of the Boltzmann equation. Comparing the energy conservation equation derived herefrom with the energy conservation equation for a viscous fluid on the brane, we find that the entropy change for the fluid in the emission process has to be negative. This peculiar effect is related to the fluid on the brane being a non-closed thermodynamic system. The negative entropy property for non-closed systems is encountered in other areas in physics also, in particular, in connection with the Casimir effect at finite temperature.     

Tunneling of Charged and Magnetized Fermions from the Reissner-Nordström Black Hole with Magnetic Charges

The Kerner-Mann fermions tunneling framework is extended to the spin particles with electric and magnetic charges in this paper. We rewrite the electromagnetic field tensor and the Lagrangian of the field corresponding to the source with electric and magnetic charges to redefine an equivalent charge. We only consider the case that the ratio of the electric charge and magnetic charge of the emission is constant and equal to the source. The result shows that when the energy conservation together with the electric charge and magnetic charge conservations are taken into account in the dynamical background space time, the emission rate agrees with the underlying unitary theory and the actual radiation spectrum of charged and magnetized fermions also derivates from the pure thermal one.     

太赫兹辐射场下的石墨烯光生载流子和光子发射

通过半经典的玻尔兹曼平衡方程理论研究了太赫兹辐射场下的石墨烯光生载流子和光子发射.研究得到了太赫兹辐射场下石墨烯的光生载流子浓度和光子发生率的解析公式.研究发现,掺杂电子浓度越小,或者温度越低,光生载流子浓度越大;掺杂电子浓度越大,或者温度越低,石墨烯的光子发射率越大.通过改变门电压或温度,可以有效地调控石墨烯光生载流子浓度和光子发射概率.理论研究结果和解析表达式对发展以石墨烯为基础的新型太赫兹光电器件具有重要的参考价值.     

具有态守恒赝隙的光子晶体中两能级原子自发辐射的增强与抑制

论证了在赝带隙光子晶体中存在一个全频率域态总数守恒规则，在完全带隙光子晶体中还存在一个局域态总数守恒规则.态总数守恒规则指出，如果一个光子晶体的态密度在某些频率范围存在相对于等效介质态密度的谷，则一定由其他频率范围内相对于等效介质态密度的峰来补偿.使用符合态总数守恒规则的态密度模型，解释了态密度调制导致的自发辐射谱增强、抑制、变窄、红移、蓝移以及谱分裂等光子晶体中的量子光学现象.该理论比较适合研究在具有赝带隙的光子晶体中大量随机分布的发光原子或分子的自发辐射行为. 关键词： 光子晶体 自发辐射 态密度 光子赝带隙     

Xe~(26+)入射Au靶离子L壳层空穴的产生与退激辐射

基于两体碰撞过程的能量与角动量守恒,推导出Xe26+离子与Au原子碰撞过程,单离子的L壳层空穴产额与离子动能的理论关系.实验测定了动能2.4-3.6Me V的Xe26+离子入射Au靶,产生的Xe的L-X射线谱,获得了射线产额与离子入射动能的实验关系.结果表明,碰撞过程产生Xe L壳层空穴的同时,产生了一定数目的 M壳层空穴,导致L壳层空穴平均荧光产额显著变大,在实验能量范围,空穴产额的理论值与射线产额的实验值存在较好的一致性.     

Angular resonances in the light emission from atoms near a grating

A two step light emission process becomes possible when atoms are placed near a metallic grating. The atoms can excite surface plasmons in the grating. The surface plasmons can then emit light. This light is emitted at certain angles determined by momentum conservation in the plane of the grating. Thus, the angles depend on the spacing of the grating. Our measurements on light from nitrogen atoms at distances, d, ranging from 10 to 100 nm from a silver grating are in agreement with a recent theory of Aravind, Hood and Metiu. We also report the effect of a nonsinusoidal grating profile and the emission of light at angles which can be predicted from a straightforward extension of the theory.     

Charged Dirac Particles’ Hawking Radiation via Tunneling of Both Horizons and Thermodynamics Properties of Kerr–Newman–Kasuya–Taub–NUT–AdS Black Holes

We investigate Hawking radiation of electrically and magnetically charged Dirac particles from a dyonic Kerr–Newman–Kasuya–Taub–NUT–Anti-de Sitter (KNKTN–AdS) black hole by considering thermal characters of both the outer and inner horizons. We apply Damour–Ruffini method and membrane method to calculate the temperature and the entropy of the inner horizon of the KNKTN–AdS black hole. The inner horizon admits thermal character with positive temperature and entropy proportional to its area. The inner horizon entropy contributes to the total entropy of the black hole in the context of Nernst theorem. Considering conservation of energy, charges, angular momentum, and the back-reaction of emitting particles to the spacetime, we obtain the emission spectra for both the inner and outer horizons. The total emission rate is obtained as the product of the emission rates of the inner and outer horizons. It deviates from the purely thermal spectrum with the leading term exactly the Boltzman factor and can bring some information out. The result thus can be treated as an explanation to the information loss paradox.     

An angle-resolved photoemission study of the chemisorption of chalcogens on Cu(100): II. Cu(100) + c(2 × 2)O

Starting with the three-step direct-transition model of ARPES for bulk materials, which was examined in the preceding paper, we propose a framework for describing changes in the photoemission spectra due to chemisorption. Normal emission ARPES data for Cu(100) with a c(2 × 2)O overlayer were obtained in the photon energy range hv = 11 to 34 eV. These spectra have been compared within the proposed framework with those obtained from clean Cu(100). Changes were found in the Cu emission features which could be explained by the relaxation of momentum conservation perpendicular to the surface in the optical excitation step and by the relaxation of momentum conservation parallel to the surface in the escape step. These changes include a photon energy dependent broadening of the d-band peak and the preferential attenuation of the sharp direct-transition feature associated with the sp-band. Some evidence for a surface resonance at the top of the d-bands has been obtained. Changes in the spectrum of scattered electrons were related to modifications of evanescent final states. A 1.3 eV wide band derived from the oxygen p_x,y-orbitals was deduced from spectra obtained at normal emission and along the $\text{Γ}\text{X}$ and $\text{Γ}\text{M}$ lines of the surface Brillouin zone. On the other hand, no emission was clearly detected from the oxygen p_z-orbitals. Oxygen induced emission above the Cu d-bands was observed and attributed to antibonding states. This emission was directed towards the bulk [011] directions.