|
|
MiniBooNE Collaboration(Aguilar-Arevalo, A. A. et al), & Sorel, M. (2010). Event Excess in the MiniBooNE Search for (nu)over-bar(mu) -> (nu)over-bar(e) Oscillations. Phys. Rev. Lett., 105(18), 181801–5pp.
Abstract: The MiniBooNE experiment at Fermilab reports results from a search for (nu) over bar (mu) -> (nu) over bar (e) oscillations, using a data sample corresponding to 5.66 x 10(20) protons on target. An excess of 20.9 +/- 14.0 events is observed in the energy range 475 < E-nu(QE) < 1250 MeV, which, when constrained by the observed <(nu)over bar>(mu) events, has a probability for consistency with the background-only hypothesis of 0.5%. On the other hand, fitting for (nu) over bar (mu) -> (nu) over bar (e) oscillations, the best-fit point has chi(2) probability of 8.7%. The data are consistent with (nu) over bar (mu) -> (nu) over bar (e) oscillations in the 0.1 to 1.0 eV(2) Delta m(2) range and with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory.
|
|
|
|
Esteves, J. N., Joaquim, F. R., Joshipura, A. S., Romao, J. C., Tortola, M., & Valle, J. W. F. (2010). A(4)-based neutrino masses with Majoron decaying dark matter. Phys. Rev. D, 82(7), 073008–8pp.
Abstract: We propose an A(4) flavor-symmetric SU(3) circle times SU(2) circle times U(1) seesaw model where lepton number is broken spontaneously. A consistent two-zero texture pattern of neutrino masses and mixing emerges from the interplay of type-I and type-II seesaw contributions, with important phenomenological predictions. We show that, if the Majoron becomes massive, such seesaw scenario provides a viable candidate for decaying dark matter, consistent with cosmic microwave background lifetime constraints that follow from current WMAP observations. We also calculate the subleading one-loop-induced decay into photons which leads to a monoenergetic emission line that may be observed in future x-ray missions such as Xenia.
|
|
|
|
Hirsch, M., Morisi, S., Peinado, E., & Valle, J. W. F. (2010). Discrete dark matter. Phys. Rev. D, 82(11), 116003–5pp.
Abstract: We propose a new motivation for the stability of dark matter (DM). We suggest that the same non-Abelian discrete flavor symmetry which accounts for the observed pattern of neutrino oscillations, spontaneously breaks to a Z(2) subgroup which renders DM stable. The simplest scheme leads to a scalar doublet DM potentially detectable in nuclear recoil experiments, inverse neutrino mass hierarchy, hence a neutrinoless double beta decay rate accessible to upcoming searches, while theta(13) = 0 gives no CP violation in neutrino oscillations.
|
|
|
|
Wu, J. J., Molina, R., Oset, E., & Zou, B. S. (2010). Prediction of Narrow N* and Lambda* Resonances with Hidden Charm above 4 GeV. Phys. Rev. Lett., 105(23), 232001–4pp.
Abstract: The interaction between various charmed mesons and charmed baryons is studied within the framework of the coupled-channel unitary approach with the local hidden gauge formalism. Several meson-baryon dynamically generated narrow N* and Lambda* resonances with hidden charm are predicted with mass above 4 GeV and width smaller than 100 MeV. The predicted new resonances definitely cannot be accommodated by quark models with three constituent quarks and can be looked for in the forthcoming PANDA/FAIR experiments.
|
|
|
|
BABAR Collaboration(del Amo Sanchez, P. et al), Lopez-March, N., Martinez-Vidal, F., Milanes, D. A., & Oyanguren, A. (2010). Measurement of CP observables in B-+/- -> DCPK +/- decays and constraints on the CKM angle gamma. Phys. Rev. D, 82(7), 072004–20pp.
Abstract: Using the entire sample of 467 x 10(6) Y(4S) -> B (B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the SLAC National Accelerator Laboratory, we perform an analysis of B-+/- -> DK +/- decays, using decay modes in which the neutral D meson decays to either CP-eigenstates or non-CP-eigenstates. We measure the partial decay rate charge asymmetries for CP-even and CP-odd D final states to be A(CP+) = 0.25 +/- 0.06 +/- 0.02 and A(CP-) = 0.09 +/- 0.07 +/- 0.02, respectively, where the first error is the statistical and the second is the systematic uncertainty. The parameter A(CP+) is different from zero with a significance of 3.6 standard deviations, constituting evidence for direct CP violation. We also measure the ratios of the charged-averaged B partial decay rates in CP and non-CP decays, RCP+ 1.18 +/- 0.09 +/- 0.05 and RCP- = 1.07 +/- 0.08 +/- 0.04. We infer frequentist confidence intervals for the angle gamma of the unitarity triangle, for the strong phase difference delta(B), and for the amplitude ratio r(B), which are related to the B- -> DK- decay amplitude by r(B)e(i(delta B-gamma)) = A(B- -> (D) over bar K-0(-)) = A(B- -> (D) over bar K-0(-))/A(B- -> (DK-)-K-0). Including statistical and systematic uncertainties, we obtain 0: 24 < rB < 0: 45 ( 0: 06 < rB < 0: 51) and, modulo 180 degrees, 11.3 degrees < gamma < 22.7 degrees or 80.8 degrees < gamma < 99.2 degrees or 157.3 degrees < gamma < 168.7 degrees (7.0 degrees < gamma < 173.0 degrees) at the 68% ( 95%) confidence level.
|
|
|
|
Cheng, Y., Csernai, L. P., Magas, V. K., Schlei, B. R., & Strottman, D. (2010). Matching stages of heavy-ion collision models. Phys. Rev. C, 81(6), 064910–8pp.
Abstract: Heavy-ion reactions and other collective dynamical processes are frequently described by different theoretical approaches for the different stages of the process, like initial equilibration stage, intermediate locally equilibrated fluid dynamical stage, and final freeze-out stage. For the last stage, the best known is the Cooper-Frye description used to generate the phase space distribution of emitted, noninteracting particles from a fluid dynamical expansion or explosion, assuming a final ideal gas distribution, or (less frequently) an out-of-equilibrium distribution. In this work we do not want to replace the Cooper-Frye description, but rather clarify the ways of using it and how to choose the parameters of the distribution and, eventually, how to choose the form of the phase space distribution used in the Cooper-Frye formula. Moreover, the Cooper-Frye formula is used in connection with the freeze-out problem, while the discussion of transition between different stages of the collision is applicable to other transitions also. More recently, hadronization and molecular dynamics models have been matched to the end of a fluid dynamical stage to describe hadronization and freeze-out. The stages of the model description can be matched to each other on space-time hypersurfaces (just like through the frequently used freeze-out hypersurface). This work presents a generalized description of how to match the stages of the description of a reaction to each other, extending the methodology used at freeze-out, in simple covariant form which is easily applicable in its simplest version for most applications.
|
|
|
|
de Campos, F., Eboli, O. J. P., Hirsch, M., Magro, M. B., Porod, W., Restrepo, D., et al. (2010). Probing neutrino oscillations in supersymmetric models at the Large Hadron Collider. Phys. Rev. D, 82(7), 075002–8pp.
Abstract: The lightest supersymmetric particle may decay with branching ratios that correlate with neutrino oscillation parameters. In this case the CERN Large Hadron Collider (LHC) has the potential to probe the atmospheric neutrino mixing angle with sensitivity competitive to its low-energy determination by underground experiments. Under realistic detection assumptions, we identify the necessary conditions for the experiments at CERN's LHC to probe the simplest scenario for neutrino masses induced by minimal supergravity with bilinear R parity violation.
|
|
|
|
CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2010). Exclusion of an Exotic Top Quark with-4/3 Electric Charge Using Soft Lepton Tagging. Phys. Rev. Lett., 105(10), 101801–7pp.
Abstract: We present a measurement of the electric charge of the top quark using p (p) over bar collisions corresponding to an integrated luminosity of 2: 7 fb(-1) at the CDF II detector. We reconstruct t (t) over bar events in the lepton + jets final state. We use soft lepton taggers to determine the flavor of the b jets, which we use to reconstruct the top quark's electric charge and exclude an exotic top quark with -4/3 charge at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.
|
|
|
|
Agullo, I., Navarro-Salas, J., Olmo, G. J., & Parker, L. (2010). Hawking Radiation by Kerr Black Holes and Conformal Symmetry. Phys. Rev. Lett., 105(21), 211305–4pp.
Abstract: The exponential blueshift associated with the event horizon of a black hole makes conformal symmetry play a fundamental role in accounting for its thermal properties. Using a derivation based on two-point functions, we show that the full spectrum of thermal radiation of scalar particles by Kerr black holes can be explicitly derived on the basis of a conformal symmetry arising in the wave equation near the horizon. The simplicity of our approach emphasizes the depth of the connection between conformal symmetry and black hole radiance.
|
|
|
|
ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2010). Commissioning of the ATLAS Muon Spectrometer with cosmic rays. Eur. Phys. J. C, 70(3), 875–916.
Abstract: The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs. We present the performance in the relevant parameters that determine the quality of the muon measurement. We discuss the single element efficiency, resolution and noise rates, the calibration method of the detector response and of the alignment system, the track reconstruction efficiency and the momentum measurement. The results show that the detector is close to the design performance and that the Muon Spectrometer is ready to detect muons produced in high energy proton-proton collisions.
|
|
