125717724
Measurement of Branching Fractions of $\tau$ Hadronic Decays
203030065
Search for anomalous couplings in the Higgs sector at LEP
Anomalous couplings of the Higgs boson are searched for through the processes e+e-→Hγ, e+e -→e+e-H and e+e -→HZ. The mass range 70 GeV<mH<190 GeV is explored using 602 pb-1 of integrated luminosity collected with the L3 detector at LEP at centre-of-mass energies s=189-209 GeV. The Higgs decay channels H→ff, H→γγ, H→Zγ and H→WW(*) are considered and no evidence is found for anomalous Higgs production or decay. Limits on the anomalous couplings d, d B, Δg1 Z, Δκγ and ξ2 are derived as well as limits on the H→γγ and H→Zγ decay rates. © 2004 Published by Elsevier B.V.
126182293
Evidence of psi(3770) nonD anti-D decay to J / psi pi+ pi-
188198310
Preliminary design of BES-III trigger system
19719907
Trigger System of BESIII
The trigger system of Beijing Spectrometer III, part of the upgrade of Beijing Electron Positron Collider, has been designed and implemented, and is ready for installation. This paper describes briefly the system components, its characteristics, and some technical issues. The system consists mainly of four parts: MDC (drift chamber) tracking subsystem, EMC (electromagnetic calorimeter) subsystem, TOF (time of flight) subsystem and global trigger. Some highlights in designing of this system includes: trigger scheme optimization with software simulation; optical transmission between trigger and FEEs to realize isolation with FEEs to avoid ground loop current interference; designed with most latest FPGA (Xilinx Spartan 3, VirtexII Pro...) for simplicity, high reliability and easy maintenance and hence smaller system; FPGA in-system programming or firmware online downloadable via onboard, panel connector and/or VME bus for modification flexibility during commissioning. Different from the usual fix delay data transmission from FEE to trigger, the RocketIO has been used as SEDES.
208868428
f1(1285) formation in two-photon collisions at LEP
Abstract The ηπ + π − final state in two-photon collisions is studied with the L3 detector at LEP, at centre-of-mass energies from 183 to 209 GeV with an integrated luminosity of 664.6 pb −1 . The f 1 (1285) meson is observed and the Q 2 dependence of its production is compared to different form factor models. The γγ -coupling parameter Γ γγ is found to be 3.5±0.6(stat.)±0.5(sys.) keV. The branching fraction Γ (f 1 (1285)→a 0 π )/ Γ (f 1 (1285)→ ηππ ) is also measured.
56571261
Rotation of surviving companion stars after type Ia supernova explosions in the WD+MS scenario
Context. In the single-degenerate (SD) scenario of type Ia supernovae (SNe Ia) the non-degenerate companion star survives the supernova (SN) explosion and thus should be visible near the center of the SN remnant and may show some unusual features. Therefore, a promising approach to test progenitor models of SNe Ia is to search for the companion star in historical SN remnants. Aims. Here we present the results of three-dimensional (3D) hydrodynamics simulations of the interaction between the SN Ia blast wave and a main-sequence companion taking into consideration its orbital motion and spin. The primary goal of this work is to investigate the rotation of surviving companion stars after SN Ia explosions in the WD+MS scenario. Methods. We used Eggleton's stellar evolution code including the optically thick accretion wind model to obtain realistic models of companion stars. The impact of the supernova blast wave on these companion stars was followed in 3D hydrodynamic simulations employing the smoothed particle hydrodynamics (SPH) code GADGET3. Results. We find that the rotation of the companion star does not significantly affect the amount of stripped mass and the kick velocity caused by the SN impact. However, in our simulations, the rotational velocity of the companion star is significantly reduced to about 14% to 32% of its pre-explosion value due to the expansion of the companion and because 55%-89% of the initial angular momentum is carried away by the stripped matter. Conclusions. Compared with the observed rotational velocity of the presumed companion star of Tycho's supernova, Tycho G, of similar to 6 km s(-1), the final rotational velocity we obtain in our simulations is still higher by at least a factor of two. Whether this difference is significant and may cast doubts on the suggestion that Tycho G is the companion of SN 1572 has to be investigated in future studies. Based on binary population synthesis results, we present for the first time the expected distribution of rotational velocities of companion stars after the SN explosion, which may provide useful information for the identification of the surviving companion in observational searches in other historical SN remnants.
16381056
Lattice QCD calculation of form factors describing the rare decays $B \to K^* \ell^+ \ell^-$ and $B_s \to \phi \ell^+ \ell^-$
The rare decays $B^0 \to K^{*0} \mu^+ \mu^-$ and $B_s \to \phi \mu^+ \mu^-$ are now being observed with enough precision to test Standard Model predictions. A full understanding of these decays requires accurate determinations of the corresponding hadronic form factors. Here we present results of lattice QCD calculations of the $B \to K^*$ and $B_s \to \phi$ form factors; we also determine the form factors relevant for the tree-level decays $B_s \to K^* \ell \nu$. We use full-QCD configurations including 2+1 flavors of sea quarks using an improved staggered action, and we employ lattice non-relativistic QCD to describe the bottom quark.
119240667
Radiative return for heavy Higgs boson at a muon collider
Higgs boson properties could be studied with a high accuracy at a muon collider via the $s$-channel resonant production. We consider the situation where the center-of-mass energy of the muon collider is off the resonance above the Higgs mass. We discuss the discovery potential for a generic heavy Higgs boson and compare different production mechanisms, including the ``radiative return,'' $Z$-boson associated production and heavy Higgs pair production. These production mechanisms do not sensitively rely on a priori knowledge of the heavy Higgs boson mass. We include various types of two-Higgs-doublet models for the comparison. We conclude that the radiative return process could provide an important option for both the heavy Higgs discovery and direct measurement of invisible decays at a high energy muon collider.
119307246
Pseudoscalar meson and heavy vector meson scattering lengths
We have systematically studied the S-wave pseudoscalar meson and heavy vector meson scattering lengths to the third order with the chiral perturbation theory, which will be helpful to reveal their strong interaction. For comparison, we have presented the numerical results of the scattering lengths (1) in the framework of the heavy meson chiral perturbation theory and (2) in the framework of the infrared regularization. The chiral expansion converges well in some channels.
13439260
Recent Developments in Supersymmetric and Hidden Sector Dark Matter
New results which correlate SUSY dark matter with LHC signals are presented, and a brief review of recent developments in supersymmetric and hidden sector dark matter is given. It is shown that the direct detection of dark matter is very sensitive to the hierarchical SUSY sparticle spectrum and the spectrum is very useful in distinguishing models. It is shown that the prospects of the discovery of neutralino dark matter are very bright on the “Chargino Wall” due to a copious number of model points on the Wall, where the NLSP is the Chargino, and the spin independent neutralino‐proton cross section is maintained at high values in the 10−44 cm2 range for neutralino masses up to ∼850 GeV. It is also shown that the direct detection of dark matter along with lepton plus jet signatures and missing energy provide dual, and often complementary, probes of supersymmetry. Finally, we discuss an out of the box possibility for dark matter, which includes dark matter from the hidden sector, which could either consist o...