Absorption/Scattering of Massless Dirac Wave from Black Hole Spacetimes with Cosmic String

In this paper we investigate the scattering of massless Dirac wave from several different black hole spacetimes (i.e. the Schwarzschild black hole, the RN extremal black hole, the Schwarzschild de Sitter black hole, and the extremal Schwarzschild de Sitter black hole) which are influenced by the cosmic string, respectively. All these cases show us that the total absorption cross sections oscillate around the geometric-optical limit and decrease with linear mass density μ of the cosmic string. All of the total scattering cross sections exhibit that the main scattering angle becomes narrower for the high partial frequency wave. Due to the influence of cosmic string, the glory peak becomes wider for larger values of linear mass density μ of the cosmic string.     

Absorption Cross Section of Einstein-Maxwell Dilation Axion Black Hole for Dirac Particles

The absorption cross section of the Einstein-Maxwell Dilaton Axion (EMDA) black hole for Dirac particles is investigated. It is shown that the absorption cross section decreases as both the v and the absolute value of the dilaton increase, but it increases as the mass of the particle increases. It is also shown that the absorption cross section for the massless Dirac particles is 1/8 of the area of the horizon, which may be an universal property for minimally coupled massless Dirac particles.     

Zero Point Energy of a Massless Scalar Field in the Cosmic String Space-Time

We consider the ground state energy of a massive scalar field in the space-time of a thick cosmic string in the 2+1 dimensional case for arbitrary angle deficit by using the zeta-function approach. Final numerical calculations were made in the massless case, only. We show that the zero point energy is negative, and for small angle deficit it is proportional to the fourth degree of the deficit.     

Absorption Cross Section of Static Einstein-Maxwell Dilation Axion Black Hole for Scalar Particles

The absorption cross section of the static Einstein-Maxwell dilaton axion （EMDA） black hole for scalar particles is investigated. It is shown that the ratio of the absorption cross section of the EMDA black hole to that of the Schwarzschild black hole decreases as the absolute value of the dilaton increases, and it becomes zero as the dilaton tends to its extremal value. It is also shown that the absorption cross section decreases as both the v and the absolute value of the dilaton increase, and it decreases as the mass of the particle decreases.     

Dirac Quasinormal Modes of Reissner-Nodstrom Black Hole Surrounded by Quintessence

Using the third-order WKB approximation, we evaluate the quasinormal frequencies of massless Dirac field perturbation around a Reissner Nordstrom black hole surrounded by a static and spherically symmetric quintessence. We study the variation of quasinormal frequencies with the quintessential state parameter ε, the total angular momentum number ｜k｜, the charge Q, and the overtone number n changes, respectively. Moreover, from the results we obtained, we find that the massless Dirac field damps more slowly due to the presence of quintessence.     

Tunneling of Dirac Particles from Kaluza-Klein Black Hole

Applying the fermions tunneling method, proposed by Kerner and Mann recently, we discuss the tunneling characteristics of Dirac particles from the stationary Kaluza-Klein black hole. To choose Gamma matrix conveniently and avoid the ergosphere dragging effect, we perform it in the dragging coordinate frame. The result shows that Hawking temperature in this case also can be reproduced by the general Dirac equation.     

Entropies of a Toroidal Black Hole Due to Scalar and Dirac Fields

Using the thin film brick-wall model, the entropies of a toroidal black hole due to scalar and Dirac fields are investigated. The entropy due to the scalar field is one fourth of the horizon area, and that due to the Dirac field is seven eighth of the area. These results are similar to that in black holes with horizon topology S ². The cutoff in toroidal black hole is chosen as the same as one in black holes with horizon topology S ², which seems to mean that the thin film brick-wall model is universal.     

Entropy of Dirac Field in Non-stationary and Slowly Changing Reissner-Nordstrom Black Hole

Using the thin film brick-wall model and WKB approximation, the entropy of the Dirac field in the nonstationary and slowly changing Reissner-Nordstrom （R-N） black hole is calculated. The result shows that the entropy of the R-N black hole is still proportional to its surface area if we choose proper cut-off.     

Entropy of Dirac Field in Non-stationary and Slowly Changing Reissner-Nordstrom Black Hole

Using the thin film brick-wall model and WKB approximation, the entropy of the Dirac field in the non-stationary and slowly changing Reissner-Nordstrom (R-N) black hole is calculated. The result shows that the entropy of the R-N black hole is still proportional to its surface area if we choose proper cut-off.     

Absorption of massless scalar wave from Schwarzschild black hole surrounded by quintessence

By using the partial wave method, we investigate the absorption of massless scalar wave from Schwarzschild black hole surrounded by the quintessence. We obtained the expression of absorption cross section
080402
Then we numerically carry out the absorption cross section and we find that the larger angular momentum quantum number l is, the smaller the corresponding maximum value of partial absorption cross section is, and that the total absorption cross section tends to geometric-optical limit σ_abs^hf≈ π b_c². We also find that higher value of ω_q (state parameter of the quintessence) corresponds the higher value of absorption cross section σ_abs.     

Absorption cross section of black holes with global monopole

We study the absorption problem for a massless scalar field propagating in general static spherically-symmetric black holes with a global monopole. The absorption cross section expression is provided using a partial-wave method, which permits us to make an elegant and powerful resummation of the absorption cross section, and to extract the physical information encoded in the sum over the partial-wave contributions.     

Absorption of a massless scalar wave from a Schwarzschild black hole surrounded by quintessence

By using the partial wave method,we investigate the absorption of a massless scalar wave from a Schwarzschild black hole surrounded by quintessence.We obtained the expression of absorption cross section σabs(ω)=π/ω2sum from l=0 to ∞(2l+1)|Tωl(ω)|2=π/ω2sum from l=0 to ∞(2l+1)Γωl(ω).Then we numerically carry out the absorption cross section and we find that the larger the angular momentum quantum number l is,the smaller the corresponding maximum value of the partial absorption cross section is,and that the total absorption cross section tends to the geometric-optical limit σ hf abs ≈πb 2 c.We also find that higher value of ω q(state parameter of quintessence) corresponds to the higher value of absorption cross section σ abs.     

ENDF/B-VIII.β与ENDF/B-VII.1中水的热中子散射截面数据对比分析

以常见的慢化剂材料轻水为例,分析了ENDF/B评价库中两个版本ENDF/B-VⅢ.β与之前ENDF/BVⅡ.1中热中子散射截面数据的差异。由于ENDF/B-VⅢ.β与ENDF/B-VⅡ.1等两个版本中热中子散射截面的温度不尽相同,为定量分析同一温度下二者的差异,通过插值方法得到了任意温度下的热中子散射截面数据。对比发现,二者在同一温度下的热中子散射数据存在差异。相对于ENDF/B-VⅡ.1评价库版本而言,基于ENDF/B-VⅢ.β评价库版本加工得到的束缚在水中的氢的热中子散射截面与ENDF/B-VⅡ.1存在较为明显的差异,两个版本给出的低温情况下的中子与靶核碰撞后的平均散射角余弦在热区的低能段出现极小的负值。此外,当温度高于室温时,在热区的低能段ENDF/B-VⅢ.β给出的平均次级中子能量要稍大于ENDF/B-VⅡ.1给出平均次级中子能量。This work takes the traditional moderator material H₂O for example, the differences between ENDF/B-VⅢ.β and ENDF/B-VⅡ.1 versions from the ENDF/B nuclear evaluated library are analyzed. In order to compare the thermal neutron scattering data between ENDF/B-VⅢ.β and ENDF/B-VⅡ.1 versions under the same temperature, the interpolation method is used to obtain the thermal neutron scattering data under arbitrary temperatures. There are some differences between ENDF/B-VⅢ.β and ENDF/B-VⅡ.1 versions, the thermal neutron scattering cross sections of H bound in H₂O within ENDF/B-VⅢ.β is different with that of ENDF/B-VⅡ.1, the scattering angle cosines of the neutron and target nuclei from the two libraries are slightly smaller than zero in lower energy range within thermal range. Moreover, the second scattering energy spectrum from ENDF/B-VⅢ.β is slightly harder than that from the ENDF/B-VⅡ.1 in higher energy range within thermal range when the temperature is higher than room temperature.     

硅片表面球形粒子散射研究

为求解硅片表面微小粒子在任意线偏振平面入射光照射下的散射光光强分布,选择了基于Mie散射的杨氏模型为依据,推导了该模型下散射光强空间分布的计算方法,并给出了0.54 μm球形粒子在垂直、倾斜入射下光强空间分布的模拟计算结果,以及入射平面第一象限内散射光强与国外已发表实验结果的比较.     

Quantum Thermal Effect of Dirac Particles in a Nonuniformly Rectilinearly Accelerating Black Hole with Electric Charge, Magnetic Charge, and Cosmological Constant

The Hawking radiation of Dirac particles in an arbitrarily rectilinearly accelerating Kinnersley black hole with electromagnetic charge and cosmological constant is investigated by using the generalized tortoise coordinate transformation. Both the location and the temperature of the event horizon depend on the time and the polar angle. The Hawking thermal radiation spectrum of Dirac particles is also derived.     

Experimental Study of Laser Bistatic Scattering from Random Deeply Rough Surface and Backscattering Enhancement

The laser bistatic scattering from some deeply rough plane samples are measured by using of the automated scattering measurement system. We observe the backscattering enhancement, which is confined to a narrow cone around the antispecular direction, and discuss the influences of roughness and dielectric properties on them.     

两个相邻目标对平面波、高斯波束的光散射

基于等效原理和互易性定理研究了两个靠近目标对平面波、高斯波束的光散射问题,给出了这一复合光散射模型的二阶散射结果。通常一阶散射结果容易求解,但由于耦合效应的复杂性,很难给出二阶散射结果的解析形式。为了解决这一问题,应用互易性定理给出了求解任意相邻介质目标二阶散射场的公式,同时借助等效原理将求解散射场公式中的体积分简化为面积分的形式,从而降低了求解难度。求解了两相邻球形粒子的复合散射场,并将求解结果与应用时域积分方程法求得的结果进行了比较。同时,还讨论了束腰半径、目标位置对散射截面及偏振度的影响。     

解析计算SM中电子混合链图传播下Compton 散射微分截面

采用电弱统一标准模型(SM), 对由参与电弱相互作用的各种混合圈构成的电子重整化链图传播子的构架方式作了详细分析, 并完成了有关解析计算, 进而获得了电子重整化链图传播子的解析计算结果. 作者又将此结果应用到Compton散射, 精确计算了电子混合链图传播下Compton散射微分截面的解析结果 . 此外, 作者还将计算结果与最低阶微分截面 和量子电动力学(QED)中电子链图传播下的Compton散射微分截面 做了具体的数值计算与对比分析, 发现 比 能更加精细的反应辐射修正效应.     

解析计算SM中电子混合链图传播下Compton散射微分截面(英文)

采用电弱统一标准模型（SM）,对由参与电弱相互作用的各种混合圈构成的电子重整化链图传播子的构架方式作了详细分析,并完成了有关解析计算,进而获得了电子重整化链图传播子的解析计算结果.作者又将此结果应用到Compton散射,精确计算了电子混合链图传播下Compton散射微分截面的解析结果dσ_SM^chain/dcosθ.此外,作者还将计算结果与最低阶微分截面dσ^trcc/dcosθ口和量子电动力学（QED）中电子链图传播下的Compton散射微分截面dσ_QED^chain/dcosθ做了具体的数值计算与对比分析,发现dσ_SM^chain/dcosθ比dσ_QED^chain/dcosθ能更加精细的反应辐射修正效应.