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Alarcon, J. M., Martin Camalich, J., Oller, J. A., & Alvarez-Ruso, L. (2011). pi N scattering in relativistic baryon chiral perturbation theory reexamined. Phys. Rev. C, 83(5), 055205–14pp.
Abstract: We have analyzed pion-nucleon scattering using the manifestly relativistic covariant framework of infrared regularization up to O(q(3)) in the chiral expansion, where q is a generic small momentum. We describe the low-energy phase shifts with a similar quality as previously achieved with heavy baryon chiral perturbation theory, root s less than or similar to 1.14 GeV. New values are provided for the O(q(2)) and O(q(3)) low-energy constants, which are compared with previous determinations. This is also the case for the scattering lengths and volumes. Finally, we have unitarized the previous amplitudes and as a result the energy range where data are reproduced increases significantly.
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Aguilar, A. C., Binosi, D., & Papavassiliou, J. (2011). Dynamical equation of the effective gluon mass. Phys. Rev. D, 84(8), 085026–19pp.
Abstract: In this article, we derive the integral equation that controls the momentum dependence of the effective gluon mass in the Landau gauge. This is accomplished by means of a well-defined separation of the corresponding “one-loop dressed” Schwinger-Dyson equation into two distinct contributions, one associated with the mass and one with the standard kinetic part of the gluon. The entire construction relies on the existence of a longitudinally coupled vertex of nonperturbative origin, which enforces gauge invariance in the presence of a dynamical mass. The specific structure of the resulting mass equation, supplemented by the additional requirement of a positive-definite gluon mass, imposes a rather stringent constraint on the derivative of the gluonic dressing function, which is comfortably satisfied by the large-volume lattice data for the gluon propagator, both for SU(2) and SU(3). The numerical treatment of the mass equation, under some simplifying assumptions, is presented for the aforementioned gauge groups, giving rise to a gluon mass that is a nonmonotonic function of the momentum. Various theoretical improvements and possible future directions are briefly discussed.
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Pierre Auger Collaboration(Abreu, P. et al), & Pastor, S. (2011). Search for first harmonic modulation in the right ascension distribution of cosmic rays detected at the Pierre Auger Observatory. Astropart Phys., 34(8), 627–639.
Abstract: We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5 x 10(17) eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.
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MiniBooNE Collaboration(Aguilar-Arevalo, A. A. et al), & Sorel, M. (2011). Measurement of nu(mu)-induced charged-current neutral pion production cross sections on mineral oil at E-nu is an element of 0.5-2.0 GeV. Phys. Rev. D, 83(5), 052009–17pp.
Abstract: Using a custom 3-Cerenkov ring fitter, we report cross sections for nu(mu)-induced charged-current single pi(0) production on mineral oil (CH2) from a sample of 5810 candidate events with 57% signal purity over an energy range of 0.5-2.0 GeV. This includes measurements of the absolute total cross section as a function of neutrino energy, and flux-averaged differential cross sections measured in terms of Q(2), mu(-) kinematics, and pi(0) kinematics. The sample yields a flux-averaged total cross section of (9.2 +/- 0.3(stat) +/- 1.5(syst)) X 10(-39) cm(2)/CH2 at mean neutrino energy of 0.965 GeV.
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2011). Measurement of the t(t)over-bar production cross section with an in situ calibration of b-jet identification efficiency. Phys. Rev. D, 83(7), 071102–8pp.
Abstract: A measurement of the top-quark pair-production cross section in p (p) over bar collisions at root s = 1.96 TeV using data corresponding to an integrated luminosity of 1.12 fb(-1) collected with the Collider Detector at Fermilab is presented. Decays of top-quark pairs into the final states ev + jets and μv+ jets are selected, and the cross section and the b-jet identification efficiency are determined using a new measurement technique which requires agreement between the measured cross sections with exactly one and with multiple identified b quarks from the top-quark decays. Assuming a top-quark mass of 175 GeV/c(2), a cross section of 8.5 +/- 0.6(stat) +/- 0.7(syst)pb is measured.
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