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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2010). Search for New Particles in Two-Jet Final States in 7 TeV Proton-Proton Collisions with the ATLAS Detector at the LHC. Phys. Rev. Lett., 105(16), 161801–19pp.
Abstract: A search for new heavy particles manifested as resonances in two-jet final states is presented. The data were produced in 7 TeV proton-proton collisions by the LHC and correspond to an integrated luminosity of 315 nb(-1) collected by the ATLAS detector. No resonances were observed. Upper limits were set on the product of cross section and signal acceptance for excited-quark (q*) production as a function of q* mass. These exclude at the 95% C. L. the q* mass interval 0: 30< m(q)*< 1:26 TeV, extending the reach of previous experiments.
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Carlson, E. D., Anderson, P. R., Fabbri, A., Fagnocchi, S., Hirsch, W. H., & Klyap, S. A. (2010). Semiclassical gravity in the far field limit of stars, black holes, and wormholes. Phys. Rev. D, 82(12), 124070–24pp.
Abstract: Semiclassical gravity is investigated in a large class of asymptotically flat, static, spherically symmetric spacetimes including those containing static stars, black holes, and wormholes. Specifically the stress-energy tensors of massless free spin 0 and spin 1/2 fields are computed to leading order in the asymptotic regions of these spacetimes. This is done for spin 0 fields in Schwarzschild spacetime using a WKB approximation. It is done numerically for the spin 1/2 field in Schwarzschild, extreme Reissner-Nordstrom, and various wormhole spacetimes. And it is done by finding analytic solutions to the leading order mode equations in a large class of asymptotically flat static spherically symmetric spacetimes. Agreement is shown between these various computational methods. It is found that, for all of the spacetimes considered, the energy density and pressure in the asymptotic region are proportional to r(-5) to leading order. Furthermore, for the spin 1/2 field and the conformally coupled scalar field, the stress-energy tensor depends only on the leading order geometry in the far field limit. This is also true for the minimally coupled scalar field for spacetimes containing either a static star or a black hole, but not for spacetimes containing a wormhole.
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Geng, L. S., Kaiser, N., Martin Camalich, J., & Weise, W. (2010). Low-energy interactions of Nambu-Goldstone bosons with D mesons in covariant chiral perturbation theory. Phys. Rev. D, 82(5), 054022–7pp.
Abstract: We calculate the scattering lengths of Nambu-Goldstone bosons interacting with D mesons in a covariant formulation of chiral perturbation theory, which satisfies heavy-quark spin symmetry and analytical properties of loop amplitudes. We compare our results with previous studies performed using heavy-meson chiral perturbation theory and show that recoil corrections are sizable in most cases.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2010). Readiness of the ATLAS Tile Calorimeter for LHC collisions. Eur. Phys. J. C, 70(4), 1193–1236.
Abstract: The Tile hadronic calorimeter of the ATLAS detector has undergone extensive testing in the experimental hall since its installation in late 2005. The readout, control and calibration systems have been fully operational since 2007 and the detector has successfully collected data from the LHC single beams in 2008 and first collisions in 2009. This paper gives an overview of the Tile Calorimeter performance as measured using random triggers, calibration data, data from cosmic ray muons and single beam data. The detector operation status, noise characteristics and performance of the calibration systems are presented, as well as the validation of the timing and energy calibration carried out with minimum ionising cosmic ray muons data. The calibration systems' precision is well below the design value of 1%. The determination of the global energy scale was performed with an uncertainty of 4%.
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2010). Diffractive W and Z production at the Fermilab Tevatron. Phys. Rev. D, 82(11), 112004–10pp.
Abstract: We report on a measurement of the fraction of events with a W or Z boson which are produced diffractively in (p) over barp collisions at root s = 1.96 TeV, using data from 0.6 fb-1 of integrated luminosity collected with the CDF II detector equipped with a Roman- pot spectrometer that detects the (p) over bar from (p) over bar + p -> (p) over bar + [X + W/Z]. We find that (1.00 +/- 0.11)% of Ws and (0.88 +/- 0.22)% of Zs are produced diffractively in a region of antiproton or proton fractional momentum loss xi of 0.03 < xi < 0.10 and 4-momentum transferred squared t of -1 < t < 0 (GeV/c)(2), where we account for the events in which the proton scatters diffractively while the antiproton dissociates, (p) over bar + p -> [X + W/Z] + p, by doubling the measured proton dissociation fraction. We also report on searches for W and Z production in double Pomeron exchange, (p) over bar + p -> [X + W/Z] + p, and on exclusive Z production, (p) over bar + p -> (p) over bar + Z + p. No signal is seen above background for these processes, and comparisons are made with expectations.
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