118734439
Search for exotic resonances decaying into WZ/ZZ in pp collisions at $ \sqrt{s}=7 $ TeV
A bstractA search for new exotic particles decaying to the VZ final state is performed, where V is either a W or a Z boson decaying into two overlapping jets and the Z decays into a pair of electrons, muons or neutrinos. The analysis uses a data sample of pp collisions corresponding to an integrated luminosity of 5 fb−1 collected by the CMS experiment at the LHC at $ \sqrt{s}=7 $ TeV in 2011. No significant excess is observed in the mass distribution of the VZ candidates compared with the background expectation from standard model processes. Model-dependent upper limits at the 95% confidence level are set on the product of the cross section times the branching fraction of hypothetical particles decaying to the VZ final state as a function of mass. Sequential standard model W′ bosons with masses between 700 and 940 GeV are excluded. In the Randall-Sundrum model for graviton resonances with a coupling parameter of 0.05, masses between 750 and 880 GeV are also excluded.
10401636
Search for di-muon decays of a low-mass Higgs boson in radiative decays of the Υ(1S)
We search for di-muon decays of a low-mass Higgs boson (A^0) produced in radiative Υ(1S) decays. The Υ(1S) sample is selected by tagging the pion pair in the Υ(2S,3S) → π^+ π^-Υ(1S) transitions, using a data sample of 92.8 × 10^6 Υ(2S) and 116.8 × 10^6 Υ(3S) events collected by the BABAR detector. We find no evidence for A^0 production and set 90% confidence level upper limits on the product branching fraction B(Υ(1S) → γA^0) × B(A^0 → μ^ +μ^-) in the range of (0.28-9.7) × 10^(-6) for 0.212 ≤ m_A^0 ≤ 9.20  GeV/c^2. The results are combined with our previous measurements of Υ(2S,3S) → γA^0, A^0 → μ^+μ^- to set limits on the effective coupling of the b quark to the A^0.
122803232
Search for Microscopic Black Hole Signatures at the Large Hadron Collider
A search for microscopic black hole production and decay in pp collisions at a center-of-mass energy of 7 TeV has been conducted by the CMS Collaboration at the LHC, using a data sample corresponding to an integrated luminosity of 35 inverse picobarns. Events with large total transverse energy are analyzed for the presence of multiple high-energy jets, leptons, and photons, typical of a signal expected from a microscopic black hole. Good agreement with the expected standard model backgrounds, dominated by QCD multijet production, is observed for various final-state multiplicities. Limits on the minimum black hole mass are set, in the range 3.5 -- 4.5 TeV, for a variety of parameters in a model with large extra dimensions, along with model-independent limits on new physics in these final states. These are the first direct limits on black hole production at a particle accelerator.
10609473
Precise measurement of the e+e- --> pi+pi-(gamma) cross section with the initial state radiation method at BABAR.
A precise measurement of the cross section of the process e(+)e(-) --> pi(+)pi(-)(gamma) from threshold to an energy of 3 GeV is obtained with the initial state radiation (ISR) method using 232 fb(-1) of data collected with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e(+)e(-) --> mu(+)mu(-)gamma(gamma). The leading-order hadronic contribution to the muon magnetic anomaly calculated using the pipi cross section measured from threshold to 1.8 GeV is (514.1 +/- 2.2(stat) +/- 3.1(syst)) x 10(-10).
2621524
Study of the mass and spin-parity of the Higgs boson candidate via its decays to Z boson pairs.
A study is presented of the mass and spin-parity of the new boson recently observed at the LHC at a mass near 125 GeV. An integrated luminosity of 17.3 fb(-1), collected by the CMS experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, is used. The measured mass in the ZZ channel, where both Z bosons decay to e or μ pairs, is 126.2 ± 0.6(stat) ± 0.2(syst) GeV. The angular distributions of the lepton pairs in this channel are sensitive to the spin-parity of the boson. Under the assumption of spin 0, the present data are consistent with the pure scalar hypothesis, while disfavoring the pure pseudoscalar hypothesis.
110632418
The BABAR detector: Upgrades, operation and performance
The BaBar detector operated successfully at the PEP-II asymmetric e +e- collider at the SLAC National Accelerator Laboratory from 1999 to 2008. This report covers upgrades, operation, and performance of the collider and the detector systems, as well as the trigger, online and offline computing, and aspects of event reconstruction since the beginning of data taking.
52249775
Medium scale anisotropy in the TeV cosmic ray flux observed by ARGO-YBJ
B. Bartoli, P. Bernardini, X. J. Bi, I. Bolognino, P. Branchini, A. Budano, A.K. Calabrese Melcarne, P. Camarri, Z. Cao, R. Cardarelli, S. Catalanotti, S. Z. Chen, T. L. Chen, P. Creti, S.W. Cui, B. Z. Dai, A. D’Amone, Danzengluobu, I. De Mitri, B. D’Ettorre Piazzoli, T. Di Girolamo, G. Di Sciascio,* C. F. Feng, Zhaoyang Feng, Zhenyong Feng, Q. B. Gou, Y.Q. Guo, H. H. He, Haibing Hu, Hongbo Hu, M. Iacovacci, R. Iuppa, H.Y. Jia, Labaciren, H. J. Li, G. Liguori, C. Liu, J. Liu, M.Y. Liu, H. Lu, X. H. Ma, G. Mancarella, S.M. Mari, G. Marsella, D. Martello, S. Mastroianni, P. Montini, C. C. Ning, M. Panareo, B. Panico, L. Perrone, P. Pistilli, F. Ruggieri, P. Salvini, R. Santonico, S. N. Sbano, P. R. Shen, X.D. Sheng, F. Shi, A. Surdo, Y. H. Tan, P. Vallania, S. Vernetto, C. Vigorito, H. Wang, C. Y. Wu, H. R. Wu, L. Xue, Y.X. Yan, Q.Y. Yang, X. C. Yang, Z. G. Yao, A. F. Yuan, M. Zha, H.M. Zhang, L. Zhang, X.Y. Zhang, Y. Zhang, Zhaxiciren, Zhaxisangzhu, X.X. Zhou, F. R. Zhu, Q.Q. Zhu, and G. Zizzi
122601384
Studies of wire gain and track distortion near the sector edges of the ALEPH time projection chamber
Abstract The materials used to hold the wires at the sector edges in a large Time Projection Chamber (TPC) inrtoduce distortions of the electric drift field near those edges. These distortions degrade tracking information and sometimes cause large changes in wire gain near the edge. We have studied these two problems for the ALEPH TPC and have found that both can be greatly reduced by the addition of two field correction strips held at appropriate voltages.
118646643
A hybrid model of GeV-TeV gamma ray emission from the Galactic center
The observations of high energy gamma-ray emission from the Galactic center (GC) by HESS, and recently by Fermi, suggest cosmic ray acceleration in the GC and possibly around the supermassive black hole. In this work we propose a lepton-hadron hybrid model to simultaneously explain the GeV-TeV gamma-ray emission. Both electrons and hadronic cosmic rays were accelerated during the previous activity of the GC. These particles would then diffuse outwards and interact with the interstellar gas and background radiation field. The collisions between hadronic cosmic rays with gas are responsible for the TeV gamma-ray emission detected by HESS. With fast cooling in the strong radiation field, the electrons would cool down and radiate GeV photons through inverse Compton scattering off the soft background photons. This scenario provides a natural explanation for the observed GeV-TeV spectral shape of gamma-ray.