del Rio, A., & Navarro-Salas, J. (2015). Equivalence of adiabatic and DeWitt-Schwinger renormalization schemes. Phys. Rev. D, 91(6), 064031–14pp.
Abstract: We prove that adiabatic regularization and DeWitt-Schwinger point-splitting provide the same result when renormalizing expectation values of the stress-energy tensor for spin-1/2 fields. This generalizes the equivalence found for scalar fields, which is here recovered in a different way. We also argue that the coincidence limit of the DeWitt-Schwinger proper time expansion of the two-point function agrees exactly with the analogous expansion defined by the adiabatic regularization method at any order (for both scalar and spin-1/2 fields). We also illustrate the power of the adiabatic method to compute higher order DeWitt coefficients in Friedmann-Lemaitre-Robertson-Walker Universes.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2015). Search for new phenomena in the dijet mass distribution using pp collision data at root s=8 TeV with the ATLAS detector. Phys. Rev. D, 91(5), 052007–25pp.
Abstract: Dijet events produced in LHC proton-proton collisions at a center-of-mass energy root s = 8 TeV are studied with the ATLAS detector using the full 2012 data set, with an integrated luminosity of 20.3 fb(-1). Dijet masses up to about 4.5 TeV are probed. No resonancelike features are observed in the dijet mass spectrum. Limits on the cross section times acceptance are set at the 95% credibility level for various hypotheses of new phenomena in terms of mass or energy scale, as appropriate. This analysis excludes excited quarks with a mass below 4.06 TeV, color-octet scalars with a mass below 2.70 TeV, heavy W' bosons with a mass below 2.45 TeV, chiral W* bosons with a mass below 1.75 TeV, and quantum black holes with six extra space-time dimensions with threshold mass below 5.66 TeV.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Dalitz plot analyses of B-0 -> (D-DK+)-K-0 and B+-> (D)over-bar(-)D(0)K(+) decays. Phys. Rev. D, 91(5), 052002–14pp.
Abstract: We present Dalitz plot analyses for the decays of B mesons to (D-DK+)-K-0 and (D) over bar (DK+)-D-0-K-0. We report the observation of the D*(s1)(2700)(+) resonance in these two channels and obtain measurements of the mass M(D*(s1)(2700)(+)) = 2699(-7)(+14) MeV/c(2) and of the width Gamma(D*(s1)(2700)(+)) = 127(-19)(+24) MeV, including statistical and systematic uncertainties. In addition, we observe an enhancement in the (DK+)-K-0 invariant mass around 2350-2500 MeV/c(2) in both decays B-0 -> (D-DK+)-K-0 and B+ -> (D) over bar (DK+)-D-0-K-0, which we are not able to interpret. The results are based on 429 fb(-1) of data containing 471 x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2015). Simultaneous measurements of the t(t)over-bar, W+W-, and Z/gamma* -> tau tau production cross-sections in pp collisions at root s=7 TeV with the ATLAS detector. Phys. Rev. D, 91(5), 052005–34pp.
Abstract: Simultaneous measurements of the t (t) over bar, W+W-, and Z/gamma* -> tau tau production cross-sections using an integrated luminosity of 4.6 fb(-1) of pp collisions at root s = 7 TeV collected by the ATLAS detector at the LHC are presented. Events are selected with two high transverse momentum leptons consisting of an oppositely charged electron and muon pair. The three processes are separated using the distributions of the missing transverse momentum of events with zero and greater than zero jet multiplicities. Measurements of the fiducial cross-section are presented along with results that quantify for the first time the underlying correlations in the predicted and measured cross-sections due to proton parton distribution functions. These results indicate that the correlated next-to-leading-order predictions for t (t) over bar and Z/gamma* -> tau tau underestimate the data, while those at next-to-next-to-leading-order generally describe the data well. The full cross-sections are measured to be sigma(t (t) over bar) = 181.2 +/- 2.8(-9.5)(+9.7) +/- 3.3 +/- 3.3 pb, sigma(W+W-) = 53.3 +/- 2.7(-8.0)(+7.3) +/- 1.0 +/- 0.5 pb, and sigma(Z/gamma* -> tau tau) = 1174 +/- 24(-87)(+72) +/- 21 +/- 9 pb, where the cited uncertainties are due to statistics, systematic effects, luminosity and the LHC beam energy measurement, respectively. The W+W- measurement includes the small contribution from Higgs boson decays, H -> W+W-.
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Anderson, P. R., Fabbri, A., & Balbinot, R. (2015). Low frequency gray-body factors and infrared divergences: Rigorous results. Phys. Rev. D, 91(6), 064061–18pp.
Abstract: Formal solutions to the mode equations for both spherically symmetric black holes and Bose-Einstein condensate acoustic black holes are obtained by writing the spatial part of the mode equation as a linear Volterra integral equation of the second kind. The solutions work for a massless minimally coupled scalar field in the s-wave or zero angular momentum sector for a spherically symmetric black hole and in the longitudinal sector of a one-dimensional Bose-Einstein condensate acoustic black hole. These solutions are used to obtain in a rigorous way analytic expressions for the scattering coefficients and gray-body factors in the zero frequency limit. They are also used to study the infrared behaviors of the symmetric two-point function and two functions derived from it: the point-split stress-energy tensor for the massless minimally coupled scalar field in Schwarzschild-de Sitter spacetime and the density-density correlation function for a Bose-Einstein condensate acoustic black hole.
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