209930395
Extraction of the structure functions in tau -> 3 pi nu decay using Li model
The structure functions in the tau --> 3 pi nu decay are extracted using the model proposed by Li. The predictions of Li model are compared with KS ones and the data from OPAL experiment. It is found that predictions by the model for w(A)(Q(2)) are consistent with the data except for in the high energy region (Q(2) > 1.2 GeV2), and w(C), w(D), w(E) normalized to w(A) are in reasonable agreement with the experimental results. Correction factors to the Breit-Wigner distribution of a(1) and the Lagrangian of this decay are proposed to the model.
121082248
Prospects of B/c mesons at the Compact Muon Solenoid
The results of two Monte Carlo generators for production of Bc mesons in pp collisions are compared at the large hadron collider energy (s)1/2 = 14 TeV. In the study, the produced Bc mesons were forced to decay into the final states Bslν, Bsπ, J/ψlν, and J/ψπ. We have estimated that about 104 decays of Bc are expected to be recorded during the first year of the CMS running with a lepton trigger. Many Bc studies can be carried out by using these events with a statistical error at the level of 10−2.
119474898
The topological branching fractions of $\tau$ decay at LEP
The paper has heen withdrawn.
120081744
Study on The Property of tau Hadronic Decays
42952558
Study of diphoton decays of the lightest scalar Higgs boson in the Next-to-Minimal Supersymmetric Standard Model
The CMS and ATLAS experiments at the LHC have announced the discovery of a Higgs boson with mass at approximately 125 GeV/c(2) in the search for the Standard Model Higgs boson via, notably, the gamma gamma and ZZ to four leptons final states. Considering the recent results of the Higgs boson searches from the LHC, we study the lightest scalar Higgs boson h(1) in the Next-to-Minimal Supersymmetric Standard Model by restricting the next-to-lightest scalar Higgs boson h(2) to be the observed to the 125 GeV/c(2) state. We perform a scan over the relevant NMSSM parameter space that is favoured by low fine-tuning considerations. Moreover, we also take the experimental constraints from direct searches, B-physics observables, relic density, and anomalous magnetic moment of the muon measurements, as well as the theoretical considerations, into account in our specific scan. We find that the signal rate in the two-photon final state for the NMSSM Higgs boson h(1) with the mass range from about 80 GeV/c(2) to about 122 GeV/c(2) can be enhanced by a factor of up to 3.5 when the Higgs boson h(2) is required to be compatible with the excess from latest LHC results. This motivates the extension of the search at the LHC for the Higgs boson h(1) in the diphoton final state down to masses of 80 GeV/c(2), particularly with the upcoming proton-proton collision data to be taken at center-of-mass energies of 13-14 TeV.
119276990
Heavy quarkonium production through the semi-exclusive $e^+e^-$ annihilation channels round the $Z^0$ peak
Within the framework of the non-relativistic QCD, we present a detailed discussion on the heavy quarkonium production at the leading order in $\alpha_s$ at a $e^+ e^-$ collider with the collision energy around the $Z^0$ peak. Quarkonia are produced through the semi-exclusive channels $e^{+}e^{-} \rightarrow |H_{Q\bar{Q}}\rangle +X$ with $X=Q\bar{Q}$ or $gg$, where $Q$ indicates a heavy quark (respectively $b$ or $c$). It is noted that in addition to the color-singlet 1S-level quarkonium states, the 2S and 1P color-singlet states and the color-octet $|(Q\bar{Q})[1^3S_1^{({\bf 8})}]g\rangle$ state also provide sizable contributions. The heavy quarkonium transverse momentum and rapidity distributions for the $e^+ e^-$ collision energy $E_{cm}=m_Z$ are presented. For both charmonium and bottomonium production via the $Z^0$ propagator, there is approximate "spin degeneracy" between the spin-triplet and spin-singlet quarkonium states. Uncertainties for the total cross sections are estimated by taking $m_c=1.50\pm0.15$ GeV and $m_b=4.90\pm0.15$ GeV. Around $E_{cm}=m_{Z}$, due to the $Z^0$-boson resonance effect, total cross sections for the channels via the $Z^0$-propagator become much larger than the channels via the virtual photon propagator. We conclude that, in addition to the $B$ factories as BaBar and Belle and the hadronic colliders as Tevatron and LHC, such a super $Z$-factory will present an excellent platform for studying the heavy quarkonium properties.
119092405
Photoproduction of heavy quarkonium at the ILC
We study the photoproduction of the heavy quarkonium at the future International Linear Collider (ILC) within the nonrelativistic QCD theory. We focus on the production channel via the subprocess $\gamma\gamma \to |[Q\bar{Q'}]_{\bf 1}(n)>+Q'+\bar{Q}$, where $Q$ and $Q'$ stand for heavy $c$- or $b$-quark, respectively. $|[Q\bar{Q'}]_{\bf 1}(n)>$ stands for color-singlet $S$-wave quarkonium, i.e., $\eta_{c}(|[c\bar{c}]_{\bf 1}(^1S_0)>)$, $J/\psi(|[c\bar{c}]_{\bf 1}(^3S_1)>)$, $B_{c}(|[c\bar{b}]_{\bf 1}(^1S_0)>)$, $B^*_{c}(|[c\bar{b}]_{\bf 1}(^3S_1)>)$, $\eta_{b}(|[b\bar{b}]_{\bf 1}(^1S_0)>)$, and $\Upsilon(|[b\bar{b}]_{\bf 1}(^3S_1)>)$, respectively. To improve the calculation efficiency, we adopt the improved helicity amplitude approach to deal with the difficulty of calculating the expressions for the yields when the quark masses cannot be neglected. Total and differential photoproduction cross sections, together with their uncertainties, have been presented. It is noted that sizable amount of $|c\bar{c}>$-charmonium and $|c\bar{b}>$-quarkonium events can be generated at the ILC. More specifically, we predict $(2.8^{+1.0}_{-0.7})\times 10^{6}$ $\eta_c$, $(5.4^{+1.9}_{-1.3})\times 10^{6}$ $J/\psi$, $(8.3^{+2.2}_{-1.8})\times 10^{4}$ $B_c$, $(4.3^{+1.1}_{-0.9})\times 10^{5}$ $B_c^*$, $(9.0^{+1.7}_{-1.4})\times 10^{3}$ $\eta_b$, and $(1.6\pm0.3)\times 10^{4}$ $\Upsilon$ events to be generated in one operation year at the ILC under the condition of $\sqrt{S}=500$ GeV and ${\cal L}\simeq 10^{36}$cm$^{-2}$s$^{-1}$.
123645235
The AMS-02 electromagnetic calorimeter
Abstract The Electromagnetic Calorimeter (ECAL) of the AMS-02 experiment is a lead-scintillanting fibers sampling calorimeter characterized by high granularity that allows to image the longitudinal and lateral showers development, a key issue to provide high electron/hadron discrimination. The light collection system and the FE electronics are designed to let the calorimeter operate over a wide energy range from few GeV up to 1 TeV. A full-scale prototype of the e.m. calorimeter was tested at Cern in October 2001 using electrons and pions beams with energy ranging from 3 to 100 GeV. Effective sampling thickness, linearity and energy resolution were measured.
63535218
Performance analysis of Cluster File System on Linux
With the development of Linux and improvement of PC’s performance, PC cluster used as high performance computing system is becoming much popular. The performance of I/O subsystem and cluster file system is critical to a high performance computing system. In this work the basic characteristics of cluster file systems and their performance are reviewed. The performance of four distributed cluster file systems, AFS, NFS, PVFS and CASTOR, were measured. The measurements were carried out on CERN Linux 7.3.3 using standard I/O performance benchmarks. Measurements show that for single-server single-client configuration, NFS, CASTOR and PVFS have better performance and write rate slightly increases while the record size becomes larger. CASTOR has the best throughput when the number of write processes increases. PVFS and CASTOR are tested on multi-server and multi-client system. The two file systems nicely distribute data I/O to all servers. CASTOR RFIO protocol shows the best utilization of network bandwidth and optimised to large data size files. CASTOR also has better scalability as a cluster file system. Based on the test some methods are proposed to improve the performance of cluster file system.
168586219
The Network Security Protection System at IHEP-Net