121257016
Underground laboratory in China
The underground laboratories and underground experiments of particle physics in China are reviewed. The Jinping underground laboratory in the Jinping mountain of Sichuan, China is the deepest underground laboratory with horizontal access in the world. The rock overburden in the laboratory is more than 2400 m. The measured cosmic-ray flux and radioactivities of the local rock samples are very low. The high-purity germanium experiments are taking data for the direct dark-matter search. The liquid-xenon experiment is under construction. The proposal of the China National Deep Underground Laboratory with large volume at Jinping for multiple discipline research is discussed.
120528491
Tau-Charm factory project at Beijing
Abstract The Tau-Charm Factory (TCF) is a proposed high luminosity e + e − collider at the threshold region of the production of τ and charm. It could provide many precision measurements and search for new phenomena in the flavor physics. IHEP, Beijing, is an ideal cite to build a TCF. The status of the feasibility study of Beijing Tau-Charm Factory (BTCF) is reported.
119474898
The topological branching fractions of $\tau$ decay at LEP
The paper has heen withdrawn.
138378034
PERFORMANCES OF THE AMS-02 ELECTROMAGNETIC CALORIMETER
120032974
Analysis and simulation of hadronic showers in a uranium gas-sampling calorimeter
Abstract The results of a simulation of the response of the L3 detector to hadrons is presented. The simulation is made on the basis of data obtained in the beam with the setup consisting of a uranium gas-sampling calorimeter with a bismuth germanium oxide calorimeter in front of it.
123519682
PROSPECT OF PARTICLE PHYSICS IN CHINA
The nuclear physics and particle physics researches in China have a long tradition. BEPC is a milestone of the particle physics in China. The many interesting physics results were obtained from BEPC. Beijing Synchrotron Radiation Facility based on BEPC became the major synchrotron radiation facility in China. The upgrade of BEPC, which will increase the luminosity by two orders of magnitude, is going smoothly. The nonaccelerator based experiments were promoted also. Professor Yang made very important contribution to Chinese physics, especially to promote the large science facilities for the multiple discipline researches. The particle physics faces the great challenges, and meets the great opportunities in the 21st century. The medium-term plan of the particle physics in China was discussed.
15021640
The Kähler potential of Abelian Higgs vortices
We calculate the Kahler potential for the Samols metric on the moduli space of Abelian Higgs vortices on R2, in two different ways. The first uses a scaling argument. The second depends on a variant of the relationship between accessory parameters and the regularized action in Liouville field theory. The Kahler potential on the moduli space of vortices on H2 is also derived, and we are led to a geometrical reinterpretation of these vortices.
84835822
Onset of radial flow in p+p collisions
It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The signal of the collective motion in p+p collisions is not as clear as in heavy-ion collisions because of the low multiplicity and large fluctuation in p+p collisions. Tsallis Blast-Wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p+p collisions from RHIC to LHC using TBW and found no appreciable radial flow in p+p collisions below √s = 900 GeV. At LHC higher energy of 7 TeV in p+p collisions, the radial flow velocity achieves an average of (β) = 0.320 ± 0.005. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC. In addition, breaking of the identified particle spectra mT scaling was also observed at LHC from a model independent test.
119277497
Meson exchange effects in elastic ep scattering at loop level and the electromagnetic form factors of the proton
A new form of two-photon exchange (TPE) effect is studied to explain the discrepancy between unpolarized and polarized experimental data in elastic ep scattering. The mechanism is based on a simple idea that apart from the usual TPE effects from box and crossed-box diagrams, the mesons may also be exchanged in elastic ep scattering by two-photon coupling at loop level. The detailed study shows such contributions to reduced unpolarized cross section (sigma(un)) and polarized observables (P-t, P-l) at fixed Q(2) are only dependent on proton's electromagnetic form factors G(E,M) and a new unknown universal parameter g. After combining this contribution with the usual TPE contributions from box and crossed-box diagrams, the ratio mu(p)G(E)/G(M) extracted from the recent precise unpolarized and polarized experimental data can be described consistently.
17995666
On the scattering of magnon boundstates
We study the scattering of magnon boundstates in the spin-chain description of planar = 4 SUSY Yang-Mills. Starting from the conjectured exact S-matrix for magnons in the SU(2) sector, we calculate the corresponding S-matrix for boundstates with an arbitrary number of constituent magnons. The resulting expression has an interesting analytic structure with both simple and double poles. We also calculate the semiclassical S-matrix for the scattering of the corresponding excitations on the string worldsheet known as Dyonic Giant Magnons. We find precise agreement with the magnon boundstate S-matrix in the limit of large 't Hooft coupling.
17280430
Survivability of a star cluster in a dispersing molecular cloud
Star clusters are formed in molecular clouds which are believed to be the birth places of most stars. From recent observational data, Lada & Lada 2003 estimated that only 4% to 7% of the clusters embedded inside molecular clouds have survived. An important mechanism for the disruption of embedded (bound)-clusters is the dispersion of the parent cloud by UV radiation, stellar winds and/or supernova explosions. In this work we study the effect of this mechanism by N-body simulations. We find that most embedded-clusters survive for more than 30 Myr even when different initial conditions of the cluster may introduce some minor variations, but the general result is rather robust.