209836116
Measurement of triple gauge boson couplings of the W boson at LEP
The CP-conserving triple-gauge-boson couplings, g(1)(Z), kappa(gamma), lambda(gamma), g(5)(Z), kappa(Z) and lambda(Z) are measured using hadronic and semi-leptonic W-pair events selected in 629 pb(-1) of data collected at LEP with the L3 detector at centre-of-mass energies between 189 and 209 GeV. The results are combined with previous L3 measurements based on data collected at lower centre-of-mass energies and with the results from single-W production and from events with a single-photon and missing energy. Imposing the constraints kappa(Z) = g(1)(Z) - tan(2) thetaw(kappa(gamma) - 1) and lambda(Z) = lambda(gamma), we obtain for the C and P conserving couplings the results:
188198310
Preliminary design of BES-III trigger system
126182293
Evidence of psi(3770) nonD anti-D decay to J / psi pi+ pi-
118744730
Partial wave analysis of ψ(2S) → $p\overline{p}η$
Using a sample of 1.06 x 10(8) psi(2) events collected with the BESIII detector at BEPCII, the decay psi(2S) -> p (p) over bar eta is studied. A partial wave analysis determines that the intermediate state N(1535) with a mass of 1524 +/- 5(-4)(+10) MeV/c(2) and a width of 130(-24-10)(+27+57) MeV/c(2) is dominant in the decay; the product branching fraction is determined to be B(psi(2S) -> N(1535)(p) over bar x B(N(1535) -> p eta + c.c. = 5.2 +/- 0.3(-1.2)(+3.2)) x 10(-5). Furthermore, the branching fraction of psi(2S) -> p (p) over bar eta is measured to be (6.4 +/- 0.2 +/- 0.6) x 10(-5). Here, the first error is statistical and the second is systematic.
209856078
Measurement of the Matrix Element for the Decay $\eta^{\prime} \to \eta \pi^+\pi^-$
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.
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.
119188137
Optimistic CoGeNT analysis
Inspired by a recently proposed model of millicharged atomic dark matter (MADM), we analyze several classes of light dark matter models with respect to CoGeNT modulated and unmodulated data, and constraints from CDMS, XENON10 and XENON100. After removing the surface contaminated events from the original CoGeNT data set, we find an acceptable fit to all these data (but with the modulating part of the signal making a statistically small contribution), using somewhat relaxed assumptions about the response of the null experiments at low recoil energies, and postulating an unknown modulating background in the CoGeNT data at recoil energies above 1.5 keVee. We compare the fits of MADM---an example of inelastic magnetic dark matter---to those of standard elastically and inelastically scattering light WIMPs (eDM and iDM). The iDM model gives the best fit, with MADM close behind. The dark matter interpretation of the DAMA annual modulation cannot be made compatible with these results however. We find that the inclusion of a tidal debris component in the dark matter phase space distribution improves the fits or helps to relieve tension with XENON constraints.
119254848
Low Mass Neutralino Dark Matter in the MSSM with Constraints from $B_s\to \mu^+\mu^-$ and Higgs Search Limits
An analysis of spin independent neutralino-proton cross sections ${\ensuremath{\sigma}}_{\mathrm{SI}}(\ensuremath{\chi}p)$ that includes this low mass region is given. The analysis is done in minimal supersymmetric standard model (MSSM) with radiative electroweak symmetry breaking (REWSB). It is found that cross sections as large as ${10}^{\ensuremath{-}40}\text{ }\text{ }{\mathrm{cm}}^{2}$ can be accommodated in MSSM within the REWSB framework. However, inclusion of sparticle mass limits from current experiments, as well as lower limits on the Higgs searches from the Tevatron, and the current experimental upper limit on ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ significantly limit the allowed parameter space reducing ${\ensuremath{\sigma}}_{\mathrm{SI}}(\ensuremath{\chi}p)$ to lie below $\ensuremath{\sim}{10}^{\ensuremath{-}41}\text{ }\text{ }{\mathrm{cm}}^{2}$ or even lower for neutralino masses around 10 GeV. These cross sections are an order of magnitude lower than the cross sections needed to explain the reported data in the recent dark matter experiments in the low neutralino mass region.
8142176
Gluino NLSP, dark matter via gluino coannihilation, and LHC signatures
The possibility that the gluino is the next to the lightest supersymmetric particle (NLSP) is discussed and it is shown that this situation arises in nonuniversal supergravity models within a significant part of the parameter space compatible with all known experimental bounds. It is then shown that the gluino NLSP (GNLSP) models lead to a compressed sfermion spectrum with the sleptons often heavier than the squarks at least for the first two generations. The relic density here is governed by gluino coannihilation which is responsible for a relatively small mass splitting between the gluino and the neutralino masses. Thus the GNLSP class of models is very predictive first because the supersymmetry (SUSY) production cross sections at the CERN LHC are dominated by gluino production and second because the gluino production itself proceeds dominantly through a single channel which allows for a direct determination of the gluino mass and an indirect determination of the neutralino mass due to a linear relation between these two masses which is highly constrained by coannihilation. A detailed analysis of these models shows that the jet production and tagged b jets from the gluino production can be discriminated from the standard model background with appropriate cuts.more » It is found that the GNLSP models can be tested with just 10 fb{sup -1} of integrated luminosity and may therefore be checked with low luminosity runs in the first data at the LHC. Thus if a GNLSP model is realized, the LHC will turn into a gluino factory through a profuse production of gluinos with typically only a small fraction < or approx. 5% of total SUSY events arising from other production modes over the allowed GNLSP model parameter space.« less
118168794
Observation of $Z_c(3900)$ both by BESIII and Belle
Using $525$ pb$^{-1}$ data collected with the BESIII detector at $e^+e^-$ central-of-mass energy 4.26 GeV, the BESIII Collaboration observed a charged charmoniumlike state $Z_c(3900)\to\pi^{\pm}J/\psi$ with mass $M[Z_c(3900)]=3899.0\pm 3.6 \pm 4.9$ MeV/c$^2$, and width $\Gamma[Z_c(3900)]=46\pm 10 \pm 20$ MeV. The significance of this state was estimated to be $>8\sigma$ in all kinds of systematic tests. Using $967$ fb$^{-1}$ data recorded by the Belle detector on or near $\Upsilon(nS)$, n=1, 2, $\cdots$, 5 resonances, the $e^+e^- \to \pi^+\pi^-J/\psi$ process has been studied through initial-state-radiation (ISR) method. Except for the $Y(4260)$ resonance, an intermediate state $Z(3900)^{\pm}$ has been observed in the $\pi^{\pm}J/\psi$ mass spectrum, with significance $>5.2\sigma$. The measured mass $M[Z(3900)^{\pm}]=3894.5\pm6.6\pm4.5$ MeV/c$^2$ and width $\Gamma[Z(3900)^{\pm}]=63\pm24\pm26$ MeV, shows good agreement with the BESIII measurement within errors, which means $Z_c(3900)$ and $Z(3900)^{\pm}$ is the same state.