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Gariazzo, S., Escudero, M., Diamanti, R., & Mena, O. (2017). Cosmological searches for a noncold dark matter component. Phys. Rev. D, 96(4), 043501–11pp.
Abstract: We explore an extended cosmological scenario where the dark matter is an admixture of cold and additional noncold species. The mass and temperature of the noncold dark matter particles are extracted from a number of cosmological measurements. Among others, we consider tomographic weak lensing data and Milky Way dwarf satellite galaxy counts. We also study the potential of these scenarios in alleviating the existing tensions between local measurements and cosmic microwave background ( CMB) estimates of the S-8 parameter, with S-8 = sigma(8)root Omega(m), and of the Hubble constant H-0. In principle, a subdominant, noncold dark matter particle with a mass m(X) similar to keV, could achieve the goals above. However, the preferred ranges for its temperature and its mass are different when extracted from weak lensing observations and from Milky Way dwarf satellite galaxy counts, since these two measurements require suppressions of the matter power spectrum at different scales. Therefore, solving simultaneously the CMB-weak lensing tensions and the small scale crisis in the standard cold dark matter picture via only one noncold dark matter component seems to be challenging.
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ANTARES and HESS Collaborations(Petroff, E. et al), Barrios-Marti, J., Hernandez-Rey, J. J., Illuminati, G., Lotze, M., Tönnis, C., et al. (2017). A polarized fast radio burst at low Galactic latitude. Mon. Not. Roy. Astron. Soc., 469(4), 4465–4482.
Abstract: We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6 +/- 0.8 pc cm(-3), a pulse duration of 2.8(-0.5)(+1.2) ms, and a measured peak flux density assuming that the burst was at beam centre of 0.7(-0.1)(+0.2) Jy. The FRB originated at a Galactic longitude and latitude of 24.66 degrees, 5.28 degrees and 25 degrees away from the Galactic Center. The burst was found to be 43 +/- 5 per cent linearly polarized with a rotation measure (RM) in the range -9 < RM < 12 rad m(-2) (95 per cent confidence level), consistent with zero. The burst was followed up with 11 telescopes to search for radio, optical, X-ray, gamma-ray and neutrino emission. Neither transient nor variable emission was found to be associated with the burst and no repeat pulses have been observed in 17.25 h of observing. The sightline to the burst is close to the Galactic plane and the observed physical properties of FRB 150215 demonstrate the existence of sight lines of anomalously low RM for a given electron column density. The Galactic RM foreground may approach a null value due to magnetic field reversals along the line of sight, a decreased total electron column density from the Milky Way, or some combination of these effects. A lower Galactic DM contribution might explain why this burst was detectable whereas previous searches at low latitude have had lower detection rates than those out of the plane.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Search for massive long-lived particles decaying semileptonically in the LHCb detector. Eur. Phys. J. C, 77(4), 224–16pp.
Abstract: A search is presented formassive long-lived particles decaying into a muon and two quarks. The dataset consists of proton-proton interactions at centre-of-mass energies of 7 and 8TeV, corresponding to integrated luminosities of 1 and 2fb(-1), respectively. The analysis is performed assuming a set of production mechanisms with simple topologies, including the production of a Higgs-like particle decaying into two long-lived particles. The mass range from 20 to 80GeV/c(2) and lifetimes from 5 to 100 ps are explored. Results are also interpreted in terms of neutralino production in different R-Parity violating supersymmetric models, with masses in the 23-198 GeV/c(2) range. No excess above the background expectation is observed and upper limits are set on the production cross-section for various points in the parameter space of theoretical models.
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Becker, P., Davesne, D., Meyer, J., Navarro, J., & Pastore, A. (2017). Solution of Hartree-Fock-Bogoliubov equations and fitting procedure using the N2LO Skyrme pseudopotential in spherical symmetry. Phys. Rev. C, 96(4), 044330–17pp.
Abstract: We present the development of the extended Skyrme N2LO pseudopotential in the case of spherical even-even nuclei calculations. The energy density functional is first presented. Then we derive the mean-field equations and discuss the numerical method used to solve the resulting fourth-order differential equation together with the behavior of the solutions at the origin. Finally, a fitting procedure for such an N2LO interaction is discussed and we provide a first parametrization. Typical ground-state observables are calculated and compared against experimental data.
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Di Valentino, E., Melchiorri, A., & Mena, O. (2017). Can interacting dark energy solve the H-0 tension? Phys. Rev. D, 96(4), 043503–11pp.
Abstract: The answer is yes. We indeed find that interacting dark energy can alleviate the current tension on the value of the Hubble constant H-0 between the cosmic microwave background anisotropies constraints obtained from the Planck satellite and the recent direct measurements reported by Riess et al. 2016. The combination of these two data sets points toward a nonzero dark matter-dark energy coupling. at more than two standard deviations, with xi = -0.26(-0.12)(+0.16) at 95% C.L., i.e. with a moderate evidence for interacting dark energy with an odds ratio of 6:1 respect to a non interacting cosmological constant. However the H-0 tension is better solved when the equation of state of the interacting dark energy component is allowed to freely vary, with a phantomlike equation of state w = -1.185 +/- 0.064 (at 68% C.L.), ruling out the pure cosmological constant case, w = -1, again at more than two standard deviations. When Planck data are combined with external datasets, as BAO, JLA Supernovae Ia luminosity distances, cosmic shear or lensing data, we find perfect consistency with the cosmological constant scenario and no compelling evidence for a dark matter-dark energy coupling.
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Gerbino, M., Freese, K., Vagnozzi, S., Lattanzi, M., Mena, O., Giusarma, E., et al. (2017). Impact of neutrino properties on the estimation of inflationary parameters from current and future observations. Phys. Rev. D, 95(4), 043512–22pp.
Abstract: We study the impact of assumptions about neutrino properties on the estimation of inflationary parameters from cosmological data, with a specific focus on the allowed contours in the n(s)/r plane, where n(s) is the scalar spectral index and r is the tensor-to-scalar ratio. We study the following neutrino properties: (i) the total neutrino mass M-i = Sigma(i)m(i) (where the index i = 1, 2, 3 runs over the three neutrino mass eigenstates); (ii) the number of relativistic degrees of freedom N-eff at the time of recombination; and (iii) the neutrino hierarchy. Whereas previous literature assumed three degenerate neutrino masses or two massless neutrino species (approximations that clearly do not match neutrino oscillation data), we study the cases of normal and inverted hierarchy. Our basic result is that these three neutrino properties induce < 1 sigma shift of the probability contours in the n(s)/r plane with both current or upcoming data. We find that the choice of neutrino hierarchy (normal, inverted, or degenerate) has a negligible impact. However, the minimal cutoff on the total neutrino mass M-v,M-min = 0 that accompanies previous works using the degenerate hierarchy does introduce biases in the n(s)/r plane and should be replaced by M-v,M-min = 0.059 eV as required by oscillation data. Using current cosmic microwave background (CMB) data from Planck and Bicep/Keck, marginalizing over the total neutrino mass M-v and over r can lead to a shift in the mean value of ns of similar to 0.3 sigma toward lower values. However, once baryon acoustic oscillation measurements are included, the standard contours in the n(s)/r plane are basically reproduced. Larger shifts of the contours in the n(s)/r plane (up to 0.8 sigma) arise for nonstandard values of N-eff. We also provide forecasts for the future CMB experiments Cosmic Origins Explorer (COrE, satellite) and Stage-IV (ground-based) and show that the incomplete knowledge of neutrino properties, taken into account by a marginalization over M-v, could induce a shift of similar to 0.4 sigma toward lower values in the determination of ns (or a similar to 0.8 sigma shift if one marginalizes over N-eff). Comparison to specific inflationary models is shown. Imperfect knowledge of neutrino properties must be taken into account properly, given the desired precision in determining whether or not inflationary models match the future data.
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Hinarejos, M., Bañuls, M. C., Perez, A., & de Vega, I. (2017). Non-Markovianity and memory of the initial state. J. Phys. A, 50(32), 335301–17pp.
Abstract: We explore in a rigorous manner the intuitive connection between the non-Markovianity of the evolution of an open quantum system and the performance of the system as a quantum memory. Using the paradigmatic case of a two-level open quantum system coupled to a bosonic bath, we compute the recovery fidelity, which measures the best possible performance of the system to store a qubit of information. We deduce that this quantity is connected, but not uniquely determined, by the non-Markovianity, for which we adopt the Breuer-Laine-Piilo measure proposed in Breuer et al (2009 Phys. Rev. Lett. 103 210401). We illustrate our findings with explicit calculations for the case of a structured environment.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2017). Search for B+ -> K+tau(+)tau(-) at the BABAR Experiment. Phys. Rev. Lett., 118(3), 031802–8pp.
Abstract: We search for the rare flavor-changing neutral current process B+ -> K+tau(+)tau(-) using data from the BABAR experiment. The data sample, collected at the center-of-mass energy of the Upsilon(4S) resonance, corresponds to a total integrated luminosity of 424 fb(-1) and to 471 x 10(6) B (B) over bar pairs. We reconstruct one B meson, produced in the Upsilon(4S) -> B+B- decay, in one of many hadronic decay modes and search for activity compatible with a B+ -> K+tau(+)tau(-) decay in the rest of the event. Each tau lepton is required to decay leptonically into an electron or muon and neutrinos. Comparing the expected number of background events with the data sample after applying the selection criteria, we do not find evidence for a signal. The resulting upper limit, at the 90% confidence level, is B(B+ -> K+tau(+)tau(-)) < 2.25 x 10(-3).
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Binosi, D., Chang, L., Papavassiliou, J., Qin, S. X., & Roberts, C. D. (2017). Natural constraints on the gluon-quark vertex. Phys. Rev. D, 95(3), 031501–7pp.
Abstract: In principle, the strong-interaction sector of the standard model is characterized by a unique renormalization-group-invariant (RGI) running interaction and a unique form for the dressed-gluonquark vertex, Gamma mu; but, whilst much has been learnt about the former, the latter is still obscure. In order to improve this situation, we use a RGI running-interaction that reconciles top-down and bottom-up analyses of the gauge sector in quantum chromodynamics (QCD) to compute dressed-quark gap equation solutions with 1,660,000 distinct Ansatze for Gamma mu. Each one of the solutions is then tested for compatibility with three physical criteria and, remarkably, we find that merely 0.55% of the solutions survive the test. Evidently, even a small selection of observables places extremely tight bounds on the domain of realistic vertex Ansatze. This analysis and its results should prove useful in constraining insightful contemporary studies of QCD and hadronic phenomena.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Search for anomalous electroweak production of WW/WZ in association with a high-mass dijet system in pp collisions at root S=8 TeV with the ATLAS detector. Phys. Rev. D, 95(3), 032001–25pp.
Abstract: A search is presented for anomalous quartic gauge boson couplings in vector-boson scattering. The data for the analysis correspond to 20.2 fb(-1) of root S = 8 TeV pp collisions and were collected in 2012 by the ATLAS experiment at the Large Hadron Collider. The search looks for the production ofWW or WZ boson pairs accompanied by a high-mass dijet system, with one W decaying leptonically and a W or Z decaying hadronically. The hadronically decaying W/Z is reconstructed as either two small-radius jets or one largeradius jet using jet substructure techniques. Constraints on the anomalous quartic gauge boson coupling parameters a 4 and a 5 are set by fitting the transverse mass of the diboson system, and the resulting 95% confidence intervals are -0.024 < alpha(4) < 0.030 and -0.028 < alpha(5) < 0.033.
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