123449156
Search for an invisibly-decaying Higgs boson at LEP
Abstract A search for a Higgs boson produced in e + e − collisions in association with a Z boson and decaying into invisible particles is performed. Data collected at LEP with the L3 detector at centre-of-mass energies from 189 to 209 GeV are used, corresponding to an integrated luminosity of 0.63 fb −1 . Events with hadrons, electrons or muons with visible masses compatible with a Z boson and missing energy and momentum are selected. They are consistent with the Standard Model expectations. A lower limit of 112.3 GeV is set at 95% confidence level on the mass of the invisibly-decaying Higgs boson in the hypothesis that its production cross section equals that of the Standard Model Higgs boson. Relaxing this hypothesis, upper limits on the production cross section are derived.
126182293
Evidence of psi(3770) nonD anti-D decay to J / psi 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.
188198310
Preliminary design of BES-III trigger system
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.
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.
120858051
Parafermion Fields Constructed by Current Algebra
In this letter, the parafermion fields constructed by current algebra are considered. It is proved that there must be a parafermion field with respect to each form of current algebra. We also obtain the corresponding representation and unitary relation of the parafermion field from any current algebra.
17668294
Sparticles at the LHC
Sparticle mass hierarchies will play an important role in the type of signatures that will be visible at the Large Hadron Collider. We analyze these hierarchies for the four lightest sparticles for a general class of supergravity unified models including nonuniversalities in the soft breaking sector. It is shown that out of nearly 104 possibilities of sparticle mass hierarchies, only a small number survives the rigorous constraints of radiative electroweak symmetry breaking, relic density and other experimental constraints. The signature space of these mass patterns at the Large Hadron Collider is investigated using a large set of final states including multi-leptonic states, hadronically decaying τs, tagged b jets and other hadronic jets. In all, we analyze more than 40 such lepton plus jet and missing energy signatures along with several kinematical signatures such as missing transverse momentum, effective mass, and invariant mass distributions of final state observables. It is shown that a composite analysis can produce significant discrimination among sparticle mass patterns allowing for a possible identification of the source of soft breaking. While the analysis given is for supergravity models, the techniques based on mass pattern analysis are applicable to wide class of models including string and brane models.
59333781
The Case for a Muon Collider Higgs Factory
Author(s): Alexahin, Y; Ankenbrandt, CM; Cline, DB; Conway, A; Cummings, MA; Benedetto, VD; Eichten, E; Delahaye, J-P; Gatto, C; Grinstein, B; Gunion, J; Han, T; Hanson, G; Hill, CT; Ignatov, F; Johnson, RP; Lebedev, V; Lederman, LM; Lipton, R; Liu, Z; Markiewicz, T; Mazzacane, A; Mokhov, N; Nagaitsev, S; Neuffer, D; Palmer, M; Purohit, MV; Raja, R; Rubbia, C; Striganov, S; Summers, D; Terentiev, N; Wenzel, H | Abstract: We propose the construction of a compact Muon Collider Higgs Factory. Such a machine can produce up to \sim 14,000 at 8\times 10^{31} cm^-2 sec^-1 clean Higgs events per year, enabling the most precise possible measurement of the mass, width and Higgs-Yukawa coupling constants.
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.
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.