TeV能区物理的进展

综述近年各种TeV能量对撞机的计划和建造情况,TeV能区物理的理论研究进展和TeV能区物理的发展前景.     

用地面阵列寻找TeV能区γ点源的方法探讨

文中探讨搜寻TeV能区γ点源的方法.讨论利用student变量t判断来自源区及背景区宇宙线事例的统计差别,并由Bayes定理与MonteCarlo模拟相结合计算源区各能段的信号数,推算蟹状星云在TeV能区的γ射线微分能谱     

太阳大耀斑期间甚高能粒子流强增加的一种机制

近年来,在太阳大耀班期间,由地面中子记录装置及地下不同深度μ子记录器记录到宇宙线粒子的短期增长(GLE)现象,其能量范围已达几百GeV,甚至可达TeV能区.本文讨论了TeV能区的增长现象可能是银河宇宙线部分粒子获得再加速,由于宇宙线粒子能谱很陡,几百GeV的再加速能量能使TeV以上能区宇宙线流强有明显增长.     

用神经网络分辨原初宇宙线成分

尝试在高山乳胶室实验中用神经网络的方法区分超高能区原初宇宙线当中的质子和原子核,对模拟数据的分析结果表明,当族事例观测能量大于500TeV时,对质子和原子核的分辨率均能稳定在80%附近;而当族事例观测能量在100TeV和500TeV之间时,对质子和原子核的分辨率均大于70%.     

10TeVγ射线的星系际红外背景光子吸收现象的研究

TeVγ射线在星系际空间传播过程中将与红外背景光子作用而被衰减或吸收.大气ˇC成像望远镜实验观测到了Mrk421和Mrk501处于活动高态时的TeVγ射线发射并测出它们的能谱.报道了利用TibetⅡ/HD阵列在1995年10月至1997年至8月收集的数据,通过Mrk421和Mrk501的能谱研究星系际红外背景光子吸收现象的初步结果.结果显示:直到30TeV能区尚未观测到Mrk421和Mrk501能谱中存在统计上具有显著意义的红外背景光子吸收10TeVγ射线的现象.     

寻找10TeV能区的γ射线暴

利用西藏羊八井大气簇射实验数据,开展了对10TeV能区γ暴的全天区搜寻. 分析了4亿个簇射事例,找出在给定的时间间隔和给定的小天区内出现的簇射事例团. 采用等天顶角方法来估计背景. 有少量事例团显示了对背景的超出,但它们的显著性还不够高,尚不足以认定为γ暴. 讨论了羊八井二期阵列实验对寻找10TeVγ暴所具有的高灵敏度.     

用羊八井ASγ实验数据寻找TeV能区的γ射线暴

γ射线暴的TeV能区辐射对研究其起源、辐射机制等是非常重要的.利用西藏羊八井ASγ实验三期阵列的重建数据,通过在给定的小天区和时间间隔内寻找较高显著性事例团的方法对TeV能区的γ射线暴进行了寻找,在计算过程中采用“等天顶角法”来估计背景.工作中采用了两种途径来寻找γ射线暴,一种是与卫星γ射线暴的符合寻找,另一种是全天区独立寻找.结果发现少量事例团对背景有明显超出,考虑试验次数后,其超出还不足以认定为γ射线暴.通过Monte Carlo模拟,给出了在95%置信水平下,到达大气顶部流强上限的估计值为3.32×10^-9—1.24×10^-7 cm^-2s^-1. 关键词： γ射线暴 TeV能区 ASγ实验 宇宙射线     

清华大学高能物理研究中心TUHEP

“清华大学高能物理研究中心”主要从事粒子物理理论和实验研究，与国内外进行学术交流，重点研究方向是TeV能区物理，同时也开展高能核物理研究。名誉主任：王乃彦院士主任：高原宁学术委员会主席：邝宇平院士中心成员：毕楷杰，陈少敏，高原宁，何红建，邝宇平，王青，张斌，庄鹏飞高能中心主办的“直线对撞机物理、探测器与加速器”国际研讨会／暑期学校于2005年7月15-20日在清华大学理学院报告厅举行。左图为参会成员合影。理论方面研究范围：粒子物理理论以及对国际上各高能物理实验的理论预言和唯象分析；中低能粒子物理及各种非微扰…     

宇宙线超高能多核心族事例

本文报道了甘巴拉山乳胶室在核乳胶片上记录的宇宙线超高能多核心族事例KOE19(ΣE_γ≈1530TeV). 分析了事例的族现象特征, 并同其它大族事例进行比较. 把事例中的几个主要核心的特性同加速器和C喷注的实验结果以及TeV能区唯象QCD理论计算结果作了比较, 讨论了TeV能区超高能粒子强相互作用的一些特征.     

用乳胶室研究超高能γ线

在云南站（海拔3200米,大气深度700克/[厘米]²）利用乳胶室观测超高能γ线.给出了能量范围在2TeV～30TeV的γ线积分能谱、垂向强度和在空气中的衰减长度.对总观测能量在5TeV～70TeV的γ线族的结果进行了讨论.     

An ampere-like law for displacement vector field and near-field optical microscopy

We make up a novel and simple theory for near field and near-field optical microscopy (NOM). Our theory is composed of two parts. The first is a formulation to calculate the scattered near field of light by a small dielectric. We state that a wavenumber-vector-independent picture appears in the theory of the near field, and we find that this is expressed by an Ampere-like law for the displacement vector field. The second part is a formulation of field intensity for far field observation and near field observation from a unified point of view. We suggest a theoretical formula for the field intensity corresponding to the NOM image and demonstrate how to understand the relation between the near field and this image.     

Collapse and revival of a single—Cooper—pair box in a single—mode quantized field

We study the quantum dynamics of a single-Cooper-pair box biased by a classical voltage and also irradiated by a single-mode quantized field. We demonstrate that under weak damping of the quantized field, the collapse-revival phenomena can exist in this system, and the oscillations of the collapse and revival depend sensitively on the initial state of the single-mode quantized field and the damping rate κ. We also demonstrate that this system can show the beats phenomena.     

Functional integral mean field expansions for nuclear many fermion systems

We present a careful analysis of the auxiliary field functional integral formalism for many fermion systems. We examine the limiting procedure used in construction of such integrals and show that a wide flexibility exists with respect to the choice of the one-body field representation upon which mean field expansions are made. We demonstrate the utility of this flexibility in the context of the evaluation of the grand canonical partition function. We examine the zero order. RPA and certain higher-order terms. The above-mentioned flexibility is reflected in the dependence of the results on a trial two-body interaction, different choices of which produce Hartree, Fock, HartreeFock or other forms of the mean field expansions. A standard variational procedure selects the Hartree-Fock as the optimal choice. With this choice we find certain corrections to previously reported RPA contribution for the Hartree mean field. We also indicate the relevance of our formulation for the recent applications of the functional integral mean field approach to nuclear dynamical problems.     

Asymptotic regime in N random interacting species

The asymptotic regime of a complex ecosystem with N random interacting species and in the presence of an external multiplicative noise is analyzed. We find the role of the external noise on the long time probability distribution of the ith density species, the extinction of species and the local field acting on the ith population. We analyze in detail the transient dynamics of this field and the cavity field, which is the field acting on the ith species when this is absent. We find that the presence or the absence of some population give different asymptotic distributions of these fields.     

Multi-window transparency and fast–slow light switching in a quadratically coupled optomechanical system assisted with three-level atoms

We study theoretically the features of the output field of a quadratically coupled optomechanical system assisted with three-level atoms. In this system, the atoms interact with the cavity field and are driven by a classical field, and the cavity is driven by a strong coupling field and a weak signal field. We find that there exists a multi-window transparency phenomenon. The width of the transparent windows can be adjusted by controlling the system parameters, including the number of the atoms, the powers of the lasers driving the atoms and driving the cavity, and the environment temperature.We also find that a tunable switch from fast light to slow light can be realized in this system.     

Dynamic behaviour of a single—Cooper—pair box in a single—mode quantized field with dissipation

We study the quantum dynamics of a single-Cooper-pair box biased by a classical voltage and also irradiated by a single-mode quantized field.We demonstrate that under the weak damping,the collapse-revival phenomena can exist in this system.We also demonstrate that the revivals of oscillations are sensitive to the initial coherent field and the damping rate of the single-mode quantized field.     

Torsion Fields, Cartan–Weyl Space–Time and State-Space Quantum Geometries, their Brownian Motions, and the Time Variables

We review the relation between spacetime geometries with trace-torsion fields, the so-called Riemann–Cartan–Weyl (RCW) geometries, and their associated Brownian motions. In this setting, the drift vector field is the metric conjugate of the trace-torsion one-form, and the laplacian defined by the RCW connection is the differential generator of the Brownian motions. We extend this to the state-space of non-relativistic quantum mechanics and discuss the relation between a non-canonical quantum RCW geometry in state-space associated with the gradient of the quantum-mechanical expectation value of a self-adjoint operator given by the generalized laplacian operator defined by a RCW geometry. We discuss the reduction of the wave function in terms of a RCW quantum geometry in state-space. We characterize the Schroedinger equation in terms of the RCW geometries and Brownian motions. Thus, in this work, the Schroedinger field is a torsion generating field, both for the linear and non-linear cases. We discuss the problem of the many times variables and the relation with dissipative processes, and the role of time as an active field, following Kozyrev and a recent experiment in non-relativistic quantum systems. We associate the Hodge dual of the drift vector field with a possible angular-momentum source for the phenomenae observed by Kozyrev.     

Dielectric relaxation in nanopillar NiFe–silicon structures in high magnetic fields

We explore the dielectric relaxation properties of NiFe nanowires in a nanoporous silicon template. Dielectric data of the NiFe–silicon structure show a strong relaxation resonance near 30 K. This system shows Arrhenius type of behavior in the temperature dependence of dissipation peaks vs. frequency. We report magnetic field dependence of dipolar relaxation rate and the appearance of structure in the dielectric spectrum related to multiple relaxation rates. A magnetic field affects both the exponential prefactor in the Arrhenius formula and the activation energy. From this field dependence we derive a simple exponential field dependence for the prefactor and linear field approximation for the activation energy which describes the data. We find a significant angular dependence of the dielectric relaxation spectrum for regular silicon and nanostructured silicon vs. magnetic field direction, and describe a simple sum rule that describes this dependence. We find that although similar behavior is observed in both template and nanostructured materials, the NiFe–silicon shows a more complex, magnetic field dependent relaxation spectrum.     

Self-Focusing and Channeling of Wave Beams in a Nonuniform Magnetic Field under Conditions of Ionization Nonlinearity

We study experimentally the effect of ionization self-channeling of waves at the whistler frequencies in a nonuniform magnetic field. It is shown that the formed plasma nonuniformity localizes the radiation from a short high-frequency source inside a discharge channel stretched along an external magnetic field. We found a possibility to control the parameters of the formed plasma-wave channel as well as the dispersion characteristics and structure of wave fields in wide limits by varying the magnetic field in a specified spatial region. We propose a method for the formation of a plasma resonator and test this method in the laboratory experiment. The spatial plasma and field distributions in this resonator are similar to those along a geomagnetic field tube of the magnetospheric resonator. We reveal the plasma instability in such a resonator in the vicinity of the frequency of electron bounce oscillations between magnetic mirrors.     

Conformal invariance and spontaneous symmetry breaking

We study the spontaneous symmetry breaking in a conformally invariant gravitational theory. We particularly emphasize on the nonminimal coupling of matter fields to gravity. By the nonminimal coupling we consider a local distinction between the conformal frames of metric of matter fieldsand the metric explicitly entering the vacuum sector. We suppose that these two frames are conformally related by a dilaton field. We show that the imposition of a condition on the variable mass term of a scalar field may lead to the spontaneous symmetry breaking. In this way the scalar field may imitate the Higgs field behavior. Attributing a constant configuration to the ground state of the Higgs field, a Higgs conformal frame is specified. We define the Higgs conformal frame as a cosmological frame which describes the large scale characteristics of the observed universe. In the cosmological frame the gravitational coupling acquires a correct value and one no longer deals with the vacuum energy problem. We then study a more general case by considering a variable configuration for the ground state of Higgs field. In this case we introduce a cosmological solution of themodel.