20388350
FPGA - Based Compute Nodes for the PANDA Experiment at FAIR
PANDA is a new universal detector for antiproton physics at the HESR facility at FAIR/GSI. The PANDA data acquisition system has to handle interaction rates of the order of 10**7 /s and data rates of several 100 Gb Is. FPGA based compute nodes with multi-Gbit/s bandwidth capability using the ATCA architecture are designed to handle tasks such as event building, feature extraction and high level trigger processing. Each board is equipped with 5 Virtex4 FX60 FPGAs. High bandwidth connectivity is provided by four Gbit Ethernet links and 8 additional optical links connected to RocketIO ports. A single ATCA crate can host up to 14 boards which are interconnected via a full mesh backplane.
188198310
Preliminary design of BES-III trigger system
126182293
Evidence of psi(3770) nonD anti-D decay to J / psi pi+ pi-
18308235
Search for new particles in hadronic events with isolated photons
Abstract A search for the neutral Higgs boson in the processes e + e − → Z → H 0 γ → q q γ and e + e − → Z → Z ∗ H 0 → q q γγ has been performed using 2.8 million hadronic Z decays collected with the L3 detector at LEP from 1991 through 1994. No evidence for these processes has been observed. Upper limits at 95% confidence level for the corresponding cross sections have been set and the results have been compared with theoretical predictions beyond the Standard Model.
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.
54185957
Colored resonant signals at the LHC: largest rate and simplest topology
We study the colored resonance production at the LHC in a most general approach. We classify the possible colored resonances based on group theory decomposition, and construct their effective interactions with light partons. The production cross section from annihilation of valence quarks or gluons may be on the order of 400–1000 pb at LHC energies for a mass of 1 TeV with nominal couplings, leading to the largest production rates for new physics at the TeV scale, and simplest event topology with dijet final states. We apply the new dijet data from the LHC experiments to put bounds on various possible colored resonant states. The current bounds range from 0.9 to 2.7 TeV. The formulation is readily applicable for future searches including other decay modes.
55532447
Nonperturbative renormalization of overlap quark bilinears on 2+1-flavor domain wall fermion configurations
Department of Physics, Zhejiang University, Hangzhou 311027, China(Received 9 January 2014; published 19 August 2014)We present renormalization constants of overlap quark bilinear operators on 2þ 1-flavor domain wallfermion configurations. This setup is being used by the χQCD Collaboration in calculations of physicalquantities such as strangeness in the nucleon and the strange and charm quark masses. The scale-independent renormalization constant for the axial-vector current is computed using the Ward identity.The renormalization constants for scalar, pseudoscalar, and vector currents are calculated in the RI-MOMscheme. Results in the MS scheme are also given. The step scaling function of quark masses in theRI-MOM scheme is computed as well. The analysis uses, in total, six different ensembles of three seaquarks, each on two lattices with sizes 24
1931250
The Stueckelberg Z prime at the LHC: discovery potential, signature spaces and model discrimination
An analysis is given of the capability of the LHC to detect narrow resonances using high luminosities and techniques for discriminating among models are discussed. The analysis is carried out with focus on the U(1)X Abelian (Higgless) Stueckelberg extension of the Standard Model (StSM) gauge group which naturally leads to a very narrow Z' resonance. Comparison is made to another class of models, i.e., models based on the warped geometry which also lead to a narrow resonance via a massive graviton (G). Methods of distinguishing the StSM Z' from the massive graviton at the LHC are analyzed using the dilepton final state in the Drell-Yan process pp?Z'?l+l? and pp?G?l+l?. It is shown that the signature spaces in the ?.Br(l+l?)-resonance mass plane for the Z prime and for the massive graviton are distinct. The angular distributions in the dilepton C-M system are also analyzed and it is shown that these distributions lie high above the background and are distinguishable from each other. A remarkable result that emerges from the analysis is the observation that the StSM model with Z' widths even in the MeV and sub-MeV range for Z' masses extending in the TeV region can produce detectable cross section signals in the dilepton channel in the Drell-Yan process with luminosities accessible at the LHC. While the result is derived within the specific StSM class of models, the capability of the LHC to probe models with narrow resonances in this range may hold more generally.
118567609
Potential Precision on Higgs Couplings and Total Width at the ILC
We outline a systematic approach to the determination of the Standard Model-like Higgs boson total width and measurable coupling parameters in a model-independent manner at the International Linear Collider (ILC) and illustrate the complementarity for operating the ILC at $250$ GeV near the $Zh$ threshold and at $500$ GeV and $1$ TeV utilizing the $WW, ZZ$ fusion processes. We perform detailed simulations for an important contributing channel to the coupling determination and for invisible decays. Without model assumptions, and combining the information for the coupling ratios from the LHC, the total width can be determined to an accuracy of about $6%$, and the couplings for the observable channels can be measured to the $(3-5)%$ level at 250 GeV, reaching $(1-3)%$ level including the 500 GeV results, with further improvements possible with a $1$ TeV run. The best precision for the branching fraction measurement of the Higgs to invisible modes can be reached at $0.5-0.7%$ around the $Zh$ threshold. Further studies from $ZZ$ fusion at higher energies may provide significant improvement for the measurements. With modest theory assumptions, the width and coupling determinations can be further improved to the percent or sub-percent level.
119244586
Composite strongly interacting dark matter
It has been suggested that cold dark matter (CDM) has difficulties in explaining tentative evidence for noncuspy halo profiles in small galaxies, and the low velocity dispersions observed in the largest Milky Way satellites ("too big to fail" problem). Strongly self-interacting dark matter has been noted as a robust solution to these problems. The elastic cross sections required are much larger than predicted by generic CDM models, but could naturally be of the right size if dark matter is composite. We explore in a general way the constraints on models where strongly interacting CDM is in the form of dark "atoms" or "molecules," or bound states of a confining gauge interaction ("hadrons"). These constraints include considerations of relic density, direct detection, big bang nucleosynthesis, the cosmic microwave background, and LHC data.