网络背景下大学物理实验教学模式探讨

随着网络的深入发展,人们的生活模式,学习模式都发生着变化。在这种背景下,对大学物理实验的教学模式进行探讨,分析了物理仿真实验与传统实践实验教学模式的互补性,提出立体教学模式的教学方式。     

Associted Production of Z Boson and a Pair of New Quarks at LHC

The associated production of Z boson and a pair of new quarks at the Large Hadron Collider （LHC） is studied. The cross sections for both sequential fermions and vector-like fermions are presented. It is found that for sequential fermions the cross sections can reach 1 - 10^2 /b for heavy quark mass mQ from 1000 GeV to 200 GeV. For vector-like quarks, the cross sections are suppressed by mixing parameter sin OL. Focusing on process pp → b＇b＇, we investigate the possibility of detecting the 6l 4- 2j signal. For a b＇ with light mass and a large branching ratio of b＇ → bZ, it is found that only several signal events （ parton level ） can be produced with 1000 fb^-1 integrated luminosity. Although the signal events are rare, all the final states are produced centrally and multi lepton final states are clear at hadron collider, which could be easily detected.     

Simulation and experiments for the Qext of a cavity beam position monitor

The external Q （Qext） of the dipole mode is a key parameter of the Cavity Beam Position Monitor （CBPM）. It determines the amplitude and length of the dipole mode signal. In this paper, Qext of a CBPM whose waveguides were open to the air was simulated and measured, and the results agreed with each other. Then four waveguide-to-coaxial cable adpaters were adjusted and assembled to the CBPM, and Qext remained unchanged. This progress provides a reliable method to evaluate Qext in the physics design without simulating the structurally complex adapters.     

Rare decays ^-Bs,d^0→e^＋e^- in a top quark two-Higgs-doublet model

In the framework of T2HDM, we calculated the new physics contributions involving neutral Higgs bosons to the branching ratios of ^-Bs,d^0→e^＋e^-（e= e,μ） decays. Comparing the theoretical predictions with the experimental upper-limits, we found that （a） The data of Br（^-Bs,d^0→e^＋e^-） give the upper bound on tanβ： tanβ≤22, while Br（^-Bs^0→e^＋e^-） give tanβ≤12 for fixed δ = 0^0, mH＋ = 350 CeV, mH^0 = 160 GeV, mh^0 = 115 GeV and mA^0 = 120 GeV; （b） A light neutral Higgs boson mass mho （mA^0） less than 50 GeV （120 GeV） is excluded by the data of branching ratios for ^-Bs,d^0→e^＋e^-（e = μ） decays with tanβ= 10; （c） The bounds on mh^0 and tanβ, or mA^0 and tanβ are strongly correlated： a smaller （larger） tanβ means a lighter （heavier） neutral Higgs boson.     

Rare decays B_(s,d)~O→e~+e~- in a top quark two-Higgs-doublet model

In the framework of T2HDM, we calculated the new physics contributions involving neutral Higgs bosons to the branching ratios of B_(s,d)~0→e~+e~-(e=e,μ) decays. Comparing the theoretical predictions with the experimental upper-limits, we found that (a) The data of Br(B_d~0→e~+e~-)give the upper bound on tanβ: tanβ≤ 22, while Br(B_s~0→e~+e~-)give tanβ≤12 for fixed δ = 0°, m_H+=350 GeV, m_Ho = 160 GeV, m_Ho= 115 GeV and m_Ao=120 GeV; (b) A light neutral Higgs boson mass m_Ho (m_Ao) less than 50 GeV (120 GeV) is excluded by the data of branching ratios for B_(s,d)~0→e~+e~-(e=μ) decays with tanβ=10; (c) The bounds on m_(h~0) and tanβ, or m_(A~0) and tanβ are strongly correlated: a smaller (larger) tanβ means a lighter (heavier) neutral Higgs boson.     

Look Better: Single Atoms in Chemistry and Single Atoms in Physics

Fostering fruitful collaboration between chemistry and physics scholars, the analysis of the differences in the practical approach to single atoms in chemistry and in physics affords a number of conceptual outcomes pointing to a more balanced and useful relationship between chemistry and physics.     

全国高考Ⅰ卷中化学与传统文化题的分析

以全国高考I卷为例,从考查方式、考查途径和命题理念等3个角度分析了化学与传统文化题的特点;从文言文水平、文字学、信息提取能力、古代化学特点及物质名称角度分析了试题对学生能力和素养的要求;从物质性质、实验基本操作及综合应用角度自创试题,举例说明复习备考思路。     

A new universality class in corpus of texts; A statistical physics study

Text can be regarded as a complex system. There are some methods in statistical physics which can be used to study this system. In this work, by means of statistical physics methods, we reveal new universal behaviors of texts associating with the fractality values of words in a text. The fractality measure indicates the importance of words in a text by considering distribution pattern of words throughout the text. We observed a power law relation between fractality of text and vocabulary size for texts and corpora. We also observed this behavior in studying biological data.     

An explicit algorithm for imbedding solid boundaries in Cartesian grids for the reactive Euler equations

We present a local and point-wise scheme for imposing reflective boundary conditions to stationary internal boundaries for solving the reactive Euler equations on Cartesian grids. The scheme is presented in two and three dimensions and can run efficiently on parallel machines while still maintaining the same advantages over other methods for enforcing internal boundary conditions. Level sets are used to represent internal solid regions along with a new local node sorting algorithm that decouples internal boundary nodes by establishing their connectivity to other internal boundary nodes. This approach allows us to enforce boundary conditions via a direct procedure, removing the need to solve a coupled system of equations numerically. We examine the accuracy and fidelity of our internal boundary algorithm by simulating flows past various solid boundaries in two and three dimensions, showing good agreement between our numerical results and experimental data.     

Flavor SU(3) topological diagram and irreducible representation amplitudes for heavy meson charmless hadronic decays:mismatch and equivalence

Flavor SU(3) analysis of B meson charmless hadronic two light pseudoscalar decays can be formulated in two different ways. One is to construct the SU(3) irreducible representation amplitude(IRA) according to effective Hamiltonian transformation properties, and the other is to draw the topological diagrams(TDA). We first point out that previous analyses of TDA and IRA approaches do not match in several aspects, in particular a few SU(3)independent amplitudes have been overlooked in the TDA approach. This has caused confusions in the past and sometimes resulted in incorrect interpretation of data. We then demonstrate that only if these amplitudes are included, a consistent and unified picture can be obtained. With the new TDA amplitudes, all charmless hadronic decays of heavy meson must have nonzero direct CP symmetries as already predicted by the IRA approach. In addition to their notable impact on CP asymmetry, the new amplitudes are also important to extract new physics information.