
ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fassi, F., Ferrer, A., et al. (2014). Search for Quantum Black Hole Production in HighInvariantMass Lepton plus Jet Final States Using pp Collisions at root s=8 TeV and the ATLAS Detector. Phys. Rev. Lett., 112(9), 091804–18pp.
Abstract: This Letter presents a search for quantum blackhole production using 20.3 fb(1) of data collected with the ATLAS detector in pp collisions at the LHC at root s = 8 TeV. The quantum black holes are assumed to decay into a final state characterized by a lepton (electron or muon) and a jet. In either channel, no event with a leptonjet invariant mass of 3.5 TeV or more is observed, consistent with the expected background. Limits are set on the product of cross sections and branching fractions for the lepton + jet final states of quantum black holes produced in a search region for invariant masses above 1 TeV. The combined 95% confidence level upper limit on this product for quantum black holes with threshold mass above 3.5 TeV is 0.18 fb. This limit constrains the threshold quantum blackhole mass to be above 5.3 TeV in the model considered.



Mena, O., PalomaresRuiz, S., & Vincent, A. C. (2014). Flavor Composition of the HighEnergy Neutrino Events in IceCube. Phys. Rev. Lett., 113(9), 091103–5pp.
Abstract: The IceCube experiment has recently reported the observation of 28 highenergy (> 30 TeV) neutrino events, separated into 21 showers and 7 muon tracks, consistent with an extraterrestrial origin. In this Letter, we compute the compatibility of such an observation with possible combinations of neutrino flavors with relative proportion (alpha(e:)alpha(mu):alpha tau)(circle plus). Although the 7: 21 tracktoshower ratio is naively favored for the canonical (1:1:1)(circle plus) at Earth, this is not true once the atmospheric muon and neutrino backgrounds are properly accounted for. We find that, for an astrophysical neutrino E2 energy spectrum, (1:1:1)(circle plus). at Earth is disfavored at 81% C. L. If this proportion does not change, 6 more years of data would be needed to exclude (1:1:1)(circle plus) at Earth at 3 sigma C.L. Indeed, with the recently released 3yr data, that flavor composition is excluded at 92% C. L. The best fit is obtained for (1:0:0)(circle plus). at Earth, which cannot be achieved from any flavor ratio at sources with averaged oscillations during propagation. If confirmed, this result would suggest either a misunderstanding of the expected background events or a misidentification of tracks as showers, or even more compellingly, some exotic physics which deviates from the standard scenario.



Particle Data Group(Olive, K. A. et al), & HernandezRey, J. J. (2014). Review of Particle Physics. Chin. Phys. C, 38(9), 090001–1658pp.
Abstract: The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,283 new measurements from 899 Japers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as heavy neutrinos, supersymmetric and technicolor particles, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Supersymmetry, Extra Dimensions, Particle Detectors, Probability, and Statistics. Among the 112 reviews are many that are new or heavily revised including those on: Dark Energy, Higgs Boson Physics, Electroweak Model, Neutrino Cross Section Measurements, Monte Carlo Neutrino Generators, Top Quark, Dark Matter, Dynamical Electroweak Symmetry Breaking, Accelerator Physics of Colliders, HighEnergy Collider Parameters, Big Bang Nucleosynthesis, Astrophysical Constants and Cosmological Parameters.



Aguilar, A. C., Binosi, D., & Papavassiliou, J. (2014). Renormalization group analysis of the gluon mass equation. Phys. Rev. D, 89(8), 085032–19pp.
Abstract: We carry out a systematic study of the renormalization properties of the integral equation that determines the momentum evolution of the effective gluon mass in pure YangMills theory, without quark effects taken into account. A detailed, allorder analysis of the complete kernel appearing in this particular equation, derived in the Landau gauge, reveals that the renormalization procedure may be accomplished through the sole use of ingredients known from the standard perturbative treatment of the theory, with no additional assumptions. However, the subtle interplay of terms operating at the level of the exact equation gets distorted by the approximations usually employed when evaluating the aforementioned kernel. This fact is reflected in the form of the obtained solutions, for which the deviations from the correct behavior are best quantified by resorting to appropriately defined renormalizationgroup invariant quantities. This analysis, in turn, provides a solid guiding principle for improving the form of the kernel, and furnishes a welldefined criterion for discriminating between various possibilities. Certain renormalizationgroup inspired Ansatze for the kernel are then proposed, and their numerical implications are explored in detail. One of the solutions obtained fulfills the theoretical expectations to a high degree of accuracy, yielding a gluon mass that is positive definite throughout the entire range of physical momenta, and displays in the ultraviolet the socalled “powerlaw” running, in agreement with standard arguments based on the operator product expansion. Some of the technical difficulties thwarting a more rigorous determination of the kernel are discussed, and possible future directions are briefly mentioned.



Aguilar, A. C., Binosi, D., Ibañez, D., & Papavassiliou, J. (2014). Effects of divergent ghost loops on the Green's functions of QCD. Phys. Rev. D, 89(8), 085008–26pp.
Abstract: In the present work, we discuss certain characteristic features encoded in some of the fundamental QCD Green's functions, for which the origin can be traced back to the nonperturbative masslessness of the ghost field, in the Landau gauge. Specifically, the ghost loops that contribute to these Green's functions display infrared divergences, akin to those encountered in the perturbative treatment, in contradistinction to the gluonic loops, for which perturbative divergences are tamed by the dynamical generation of an effective gluon mass. In d = 4, the aforementioned divergences are logarithmic, thus causing a relatively mild impact, whereas in d = 3 they are linear, giving rise to enhanced effects. In the case of the gluon propagator, these effects do not interfere with its finiteness, but make its first derivative diverge at the origin, and introduce a maximum in the region of infrared momenta. The threegluon vertex is also affected, and the induced divergent behavior is clearly exposed in certain special kinematic configurations, usually considered in lattice simulations; the sign of the corresponding divergence is unambiguously determined. The main underlying concepts are developed in the context of a simple toy model, which demonstrates clearly the interconnected nature of the various effects. The picture that emerges is subsequently corroborated by a detailed nonperturbative analysis, combining lattice results with the dynamical integral equations governing the relevant ingredients, such as the nonperturbative ghost loop and the momentumdependent gluon mass.



del Rio, A., & NavarroSalas, J. (2014). Spacetime correlators of perturbations in slowroll de Sitter inflation. Phys. Rev. D, 89(8), 084037–7pp.
Abstract: Twopoint correlators and selfcorrelators of primordial perturbations in quaside Sitter spacetime backgrounds are considered. For large separations twopoint correlators exhibit nearly scale invariance, while for short distances selfcorrelators need standard renormalization. We study the deformation of twopoint correlators to smoothly match the selfcorrelators at coincidence. The corresponding angular power spectrum is evaluated in the SachsWolfe regime of low multipoles. Scale invariance is maintained, but the amplitude of C(l)could change in a nontrivial way.



Babichev, E., & Fabbri, A. (2014). Rotating black holes in massive gravity. Phys. Rev. D, 90(8), 084019–7pp.
Abstract: We present a solution for rotating black holes in massive gravity. We first give a solution of massive gravity with one dynamical metric. Both metrics of this solution are expressed in the advanced EddingtonFinkelsteinlike coordinates: the physical metric has the original Kerr line element, while the fiducial metric is flat, but written in a rotating EddingtonFinkelstein form. For the bigravity theory we give an analogue of this solution: the two metrics have the original Kerr form, but, in general, different black hole masses. The generalization of the solution to include the electric charge is also given; it is an analogue of the KerrNewman solution in general relativity. We also discuss further possible ways to generalize the solutions.



del Rio, A., NavarroSalas, J., & Torrenti, F. (2014). Renormalized stressenergy tensor for spin1/2 fields in expanding universes. Phys. Rev. D, 90(8), 084017–15pp.
Abstract: We provide an explicit expression for the renormalized expectation value of the stressenergy tensor of a spin1/2 field in a spatially flat FriedmannLemaitreRobertsonWalker universe. Its computation is based on the extension of the adiabatic regularization method to fermion fields introduced recently in the literature. The tensor is given in terms of UVfinite integrals in momentum space, which involve the mode functions that define the quantum state. As illustrative examples of the method efficiency, we see how to compute the renormalized energy density and pressure in two interesting cosmological scenarios: a de Sitter spacetime and a radiationdominated universe. In the second case, we explicitly show that the latetime renormalized stressenergy tensor behaves as that of classical cold matter. We also check that, if we obtain the adiabatic expansion of the scalar field mode functions with a similar procedure to the one used for fermions, we recover the wellknown WKBtype expansion.



LHCb Collaboration(Aaij, R. et al), MartinezVidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). First Measurement of the Charge Asymmetry in BeautyQuark Pair Production. Phys. Rev. Lett., 113(8), 082003–9pp.
Abstract: The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in b (b) over bar pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0 fb(1) collected at 7 TeV centerofmass energy in protonproton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the b (b) over bar system. The results obtained are A(C)(b (b) over bar) (40 < Mb<(b)over bar> < 75 GeV/c(2)) = 0.4 +/ 0.4 +/ 0.3%, A(C)(b (b) over bar) (75 < Mb<(b)over bar> < 105 GeV/c(2)) = 2.0 +/ 0.9 +/ 0.6%, A(C)(b (b) over bar) (Mb (b) over bar > 10(5) GeV/c(2)) = 1.6 +/ 1.7 +/ 0.6%,where A(C)(b (b) over bar) is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark, where in each case the first uncertainty is statistical and the second systematic. The beauty jets are required to satisfy 2 < eta < 4, ET > 20 GeV, and have an opening angle in the transverse plane Delta phi > 2.6 rad. These measurements are consistent with the predictions of the standard model.



Babichev, E., & Fabbri, A. (2014). Stability analysis of black holes in massive gravity: A unified treatment. Phys. Rev. D, 89(8), 081502–5pp.
Abstract: We consider the analytic solutions of massive (bi) gravity which can be written in a simple form using advanced EddingtonFinkelstein coordinates. We analyze the stability of these solutions against radial perturbations. First we recover the previously obtained result on the instability of the bidiagonal biSchwarzschild solutions. In the nonbidiagonal case (which contains, in particular, the Schwarzschild solution with Minkowski fiducial metric), we show that generically there are physical spherically symmetric perturbations, but no unstable modes.

