- The Physics of Elementary Particles and Fields(17)
- Library Science(2)
- General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.(2)
- Mathematics （General）(1)
- Applied Mathematics(1)
- Control and Optimization.(1)
- Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics(1)
- Condensed Matter: Structural, Mechanical and Thermal Properties(1)
- Interdisciplinary Physics and Related Areas of Science and Technology(1)

All Results

全人教育型图书馆的差异化服务模式—以香港城市大学邵逸夫图书馆为例

张秋; 顾立平Subjects: Library Science，Information Science >> Library Science

本文从全人教育的角度，分析香港城市大学邵逸夫图书馆的馆藏、空间和 服务，提出发展全人教育型图书馆的差异化服务模式。其中包括：发掘差异化学科资源需求，根据需求差异配置不同资源，根据差异资源开展各类研究、教学、学习服务，以及整合各类差异化服务发展全人教育型图书馆。 |

submitted time
2016-07-31
Hits*1699*，
Downloads*1037*，
Comment
*0*

图书馆管理中社会网络关系的问题解决模式—以香港城市大学图书馆次级团体为例

顾立平Subjects: Library Science，Information Science >> Library Science

过文献分析法、观察法以及社会网络分析法，描绘了图书馆内部员工的人际网络关系图：威胁组织的次级团体、硬性的组织关系、软性的社团关系。在此基础上，讨论了非正式社团对正式组织的影响。建议未来运用社会关系网络的方法来进行“软硬兼施”的人力资源管理，以提升图书馆团队的团结士气、和谐文化和工作效率。 |

submitted time
2016-07-31
Hits*1839*，
Downloads*1143*，
Comment
*0*

Subjects: Physics >> The Physics of Elementary Particles and Fields

Kibble mechanism drastically underestimates the production of point-like topological defects, as confirmed recently in atomic and condensed matter systems If non-thermally produced, they can be cosmological dark matter of mass 1-10 PeV or heavier If thermalized, skyrimon of mass 1-10 TeV is also a viable dark matter candidate, whose decay may explain e(+/-) spectra in cosmic rays recently measured by PAMELA, FERMI, and HESS Collaborations Models that produce magnetic monopoles below the inflation scale, such as Pati-Salam unification, are ruled out unless new annihilation mechanism for monopoles is introduced (C) 2010 Elsevier B V All rights reserved |

Models of baryogenesis via spontaneous Lorentz violation

Carroll, Sean M.; Shu, JingSubjects: Physics >> The Physics of Elementary Particles and Fields

In the presence of background fields that spontaneously violate Lorentz invariance, a matter-antimatter asymmetry can be generated even in thermal equilibrium. In this paper we systematically investigate models of this type, showing that either high-energy or electroweak versions of baryogenesis are possible, depending on the dynamics of the Lorentz-violating fields. In addition to the previously studied models of spontaneous baryogenesis and quintessential baryogenesis, we identify two scenarios of interest: baryogenesis from a weak-scale pseudo-Nambu-Goldstone boson with intermediate-scale baryon-number violation, and sphaleron-induced baryogenesis driven by a constant-magnitude vector with a late-time phase transition. |

Baryogenesis from an earlier phase transition

Shu, Jing; Tait, Tim M. P.; Wagner, Carlos E. M.Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We explore the possibility that the observed baryon asymmetry of the Universe is the result of an earlier phase transition in which an extended gauge sector breaks down into the SU(3)(C)xSU(2)(L)xU(1)(Y) of the standard model. Our proto-typical example is the topflavor model, in which there is a separate SU(2)(1) for the third generation from the SU(2)(2) felt by the first two generations. We show that the breakdown of SU(2)(1)xSU(2)(2)-> SU(2)(L) results in lepton number being asymmetrically distributed throughout the three families, and provided the SM electroweak phase transition is not strongly first order, results in a nonzero baryon number, which for parameter choices that can be explored at the LHC may explain the observed baryon asymmetry. |

Kaluza-Kleingluons as a diagnostic of warped models

Lillie, Ben; Shu, Jing; Tait, Tim M. P.Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We study the properties of g(1), the first excited state of the gluon in representative variants of the Randall-Sundrum (RS) model with the standard model (SM) fields in the bulk. We find that measurements of the coupling to light quarks (from the inclusive cross section for pp -> g(1)-> t (t) over bar), the coupling to bottom quarks (from the rate of pp -> g(1)b), as well as the overall width can provide powerful discriminants between the models. In models with large brane kinetic terms, the g(1) resonance can even potentially be discovered decaying into dijets against the large QCD background. We also derive bounds based on existing Tevatron searches for resonant t (t) over bar production and find that they require M(g)(1)greater than or similar to 950 GeV. In addition, we explore the pattern of interference between the g(1) signal and the nonresonant SM background, defining an asymmetry parameter for the invariant mass distribution. The interference probes the relative signs of the couplings of the g(1) to light quark pairs and to t (t) over bar, and thus provides an indication that the top is localized on the other side of the extra dimension from the light quarks, as is typical in the RS framework. |

Computations of superstring amplitudes in pure spinor formalism via Cadabra

Sun, Kesheng; Ding, Xiangmao; Sun, Fei; Zhang, HaibinSubjects: Physics >> The Physics of Elementary Particles and Fields

In this paper, we will illustrate how computer algebra system Cadabra is used in computing the supersymmetric amplitude in pure spinor formalism and provide the source code that computes the tree-level massless 5-gluon amplitude. |

Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

A robust solid state diffusion joining technique for SiC ceramics was designed with thickness-controlled Ti interlayer formed by Physical Vapor Deposition method and joined by Electric Field-Assisted Sintering Technology. The interface reaction and phase revolution process were investigated in details, and was analyzed in term of equilibrium phase diagram and also concentration-dependent potential diagram of Ti-Si-C ternary system. Interestingly, on the same joining conditions (fixed temperature and annealing duration), the thickness of Ti interlayer determined the concentration and distribution of reactants of Si and C elements in the resultant joint layer, and the respective diffusion distance of Si and C into Ti interlayer dramatically differentiated during the short joining process (only 5 min). In the case of 100nm thickness Ti interlayer, the C concentration saturated quickly in the joint layer and benefited the formation of TiC phase and following Ti3SiC2 phase. When the Ti thickness increase to 1μm, Si atoms easily diffuse through the diluted Ti-C alloy (dense TiC phase not formed), and amount of Ti5Si3 brittle phase was preferential formed. When the thickness of Ti interlayer is 100nm, SiC ceramics were successfully joined at low temperature of 1000°C for 20min with a flexural strength of 168.2MPa which satisfies the application in corrosion environment. All above findings revealed the importance of diffusion kinetics of reactants on the final composition in the solid state reaction, especially in the joining technique for the covalent SiC ceramics. The well-controlled composition in the joint layer of SiC couples will find its application merits in the harsh service environments, such as nuclear cladding for accident-tolerant fuel (ATF) in the environment of steam corrosion, high neutron irradiation, high temperature, etc.). |

An efficient m-step Levenberg-Marquardt method for nonlinear equations

Chen, Liang; Ma, Yanfang; Su, ChenchengSubjects: Mathematics >> Control and Optimization.

In this paper, we construct and analyze an efficient m-step Levenberg-Marquardt method for nonlinear equations. The main advantage of this method is that the m-step LM method could save more Jacobian calculations with frozen $(J_k^TJ_k+\lambda_kI)^{-1}J_k^T$ at every iteration. Under the local error bound condition which is weaker than nonsingularity, the m-step LM method has been proved to have $(m+1)$th convergence order. The global convergence has also been given by trust region technique. Numerical results show that the m-step LM method is efficient and could save many calculations of the Jacobian especially for large scale problems. |

submitted time
2016-07-11
Hits*2878*，
Downloads*1271*，
Comment
*0*

Top compositeness at the Tevatron and LHC

Lillie, Ben; Shu, Jing; Tait, Tim M. P.Subjects: Physics >> The Physics of Elementary Particles and Fields

We explore the possibility that the right-handed top quark is composite. We examine the consequences that compositeness would have on t (t) over bar production at the Tevatron, and derive a weak constraint on the scale of compositeness of order a few hundred GeV from the t (t) over bar inclusive cross section. More detailed studies of differential properties of t (t) over bar production could potentially improve this limit. We find that a composite top can result in an enhancement of the t (t) over bart (t) over bar production rate at the LHC (of as much as 10(3) compared to the Standatd Model four top rate). We explore observables which allow us to extract the four top rate from the backgrounds, and show that the LHC can either discover or constrain top compositeness for wide ranges of parameter space. |