Mon·Nov 14, 2016Monday·November 14, 2016

1. 01*

   The strong coupling from hadronic $\tau$ decays: a critical appraisal

   Diogo Boito🇧🇷 · Maarten Golterman🇺🇸 · Kim Maltman🇦🇺 · Santiago Peris🇪🇸

   Several different analysis methods have been developed to determine the strong coupling via finite-energy sum-rule analyses of hadronic $\tau$ decay data. While most methods agree on the existence of the well-known ambiguity in the choice of a resummation scheme due to the slow convergence of QCD perturbation theory at the $\tau$ mass, there is an ongoing controversy over how to deal properly with non-perturbative effects. These are small, but not negligible, and include quark-hadron "duality violations" (i.e., resonance effects) which are not described by the operator product expansion (OPE). In one approach, an attempt is made to suppress duality violations enough that they might become negligible. The number of OPE parameters to be fit, however, then exceeds the number of available sum rules, necessitating an uncontrolled OPE truncation, in which a number of higher-dimension OPE contributions in general present in QCD are set to zero by hand. In the second approach, truncation of the OPE is avoided by construction, and duality violations are taken into account explicitly, using a physically motivated model. In this article, we provide a critical appraisal of a recent analysis employing the first approach and demonstrate that it fails to properly account for non-perturbative effects, making the resulting determination of the strong coupling unreliable. The second approach, in contrast, passes all self-consistency tests, and provides a competitive determination of the strong coupling from $\tau$ decays.

   hep-phhep-exhep-latPRD(2017)·59 citations
2. 02*

   Electric dipole moments of charged leptons with sterile fermions

   Asmaa Abada🇫🇷 · Takashi Toma🇫🇷

   We address the impact of sterile fermions on charged lepton electric dipole moments. We show that in order to have a non-vanishing contribution to electric dipole moments, the minimal extension necessitates the addition of at least two sterile fermion states. Sterile neutrinos can give significant contributions to the charged lepton electric dipole moments if the masses of the non-degenerate sterile states are both above the electroweak scale. In addition, the Majorana nature of neutrinos is also important. Furthermore, we apply the computations of the electric dipole moments for the most minimal realisation of the Inverse Seesaw mechanism, in which the Standard Model is extended by two right-handed neutrinos and two sterile fermion states. We show that the two pairs of (heavy) pseudo-Dirac mass eigenstates can give significant contributions to the electron electric dipole moment, lying close to future experimental sensitivity. We further discuss the possibility of beyond the minimal Inverse Seesaw models and of having a successful leptogenesis in this framework.

   hep-ph0 citations
3. 03*

   Non-renormalizable Operators for Solar Mass Generation in Split SuSy with Bilinear R-parity Violation

   Marco Aurelio Diaz🇨🇱 · Benjamin Koch🇨🇱 · Nicolas Rojas🇪🇸

   The Minimal Supersymmetric Extension of the Standard Model (MSSM) is able to explain the current data from neutrino physics. Unfortunately Split Supersymmetry as low energy approximation of this theory fails to generate a solar square mass difference, including after the addition of bilinear R-Parity Violation. In this work, it is shown how one can derive an effective low energy theory from the MSSM in the spirit of Split Supersymmetry, which has the potential of explaining the neutrino phenomenology. This is achieved by going beyond leading order in the process of integrating out heavy scalars from the original theory, which results in non-renormalizable operators in the effective low energy theory. It is found that in particular a $d=8$ operator is crucial for the generation of the neutrino mass differences.

   hep-phNPB(2017)·0 citations
4. 04*

   Self-interacting Dark Matter Without Direct Detection Constraints

   Yue Zhang🇺🇸

   We explore the self-interacting dark matter scenario in a simple dark sector model where the dark matter interacts through a dark photon. Splitting a Dirac fermion dark matter into two levels using a small Majorana mass can evade strong direct detection constraints on the kinetic mixing between the dark and normal photons, thus allowing the dark sector to be more visible at high intensity and/or high energy experiments. It is pointed out that such a mass splitting has a strong impact on the dark matter self-interaction strength. We derive the new parameter space of a pseudo-Dirac self-interacting dark matter. Interestingly, with increasing mass splitting, a weak scale dark matter mass window survives that could be probed by the LHC and future colliders.

   hep-phastro-ph.COhep-exPhys.Dark Univ.(2017)·60 citations
5. 05*

   How to employ ${\bar{B}}_d^0\to J/\psi (\pi \eta ,\bar{K}K)$ decays to extract information on $\pi \eta$ scattering

   M. Albaladejo🇪🇸 · J. T. Daub🇩🇪 · C. Hanhart🇩🇪 · B. Kubis🇩🇪 · B. Moussallam🇫🇷

   We demonstrate that dispersion theory allows one to deduce crucial information on $\pi \eta$ scattering from the final-state interactions of the light mesons visible in the spectral distributions of the decays ${\bar{B}}_d^0\to J/\psi ({\pi }^0\eta ,K^{+}{K}^{-},K^0{\bar{K}}^0)$. Thus high-quality measurements of these differential observables are highly desired. The corresponding rates are predicted to be of the same order of magnitude as those for ${\bar{B}}_d^0\to J/\psi {\pi }^{+}{\pi }^{-}$ measured recently at LHCb, letting the corresponding measurement appear feasible.

   hep-phhep-exJHEP(2017)·31 citations
6. 06*

   LHCb anomalies from a natural perspective

   Isabel Garcia Garcia🇬🇧

   Tension between the Standard Model (SM) and data concerning $b\to s$ processes has become apparent. Most notoriously, concerning the $R_K$ ratio, which probes lepton non-universality in $b$ decays, and measurements involving the decays $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ and $B_s\to \varphi {\mu }^{+}{\mu }^{-}$. Careful analysis of a wide range of $b\to s$ data shows that certain kinds of new physics can significantly ameliorate agreement with experiment. Here, we show that these $b\to s$ anomalies can be naturally accommodated in the context of Natural Scherk-Schwarz Theories of the Weak Scale -- a class of models designed to address the hierarchy problem. No extra states need to be introduced in order to accommodate these anomalies, and the assumptions required regarding flavor violating couplings are very mild. Moreover, the structure of the theory makes sharp predictions regarding $B$ meson decays into final states including ${\tau }^{+}{\tau }^{-}$ pairs, which will provide a future test of these models.

   hep-phhep-exJHEP(2017)·59 citations
7. 07*

   Strong decays of $2^{+}$ charm and charm-strange mesons

   Si-Cheng Zhang🇨🇳 · Tianhong Wang🇨🇳 · Yue Jiang🇨🇳 · Qiang Li🇨🇳 · Guo-Li Wang🇨🇳

   In this paper, we calculate the strong decays of $2^{+}$ heavy-light states, namely, the charmed $D_2^{\ast }(2460{)}^0$ meson and the charm-strange $D_{s2}^{\ast }(2573{)}^{+}$ meson. The method we adopt is the reduction formula, PCAC relation and low energy theorem, following which, the transition amplitudes are calculated. The wave functions of the heavy mesons involved are achieved by solving the instantaneous Bethe-Salpeter equation. As the OZI-allowed two-body strong decays give the dominant contribution, they can be used to estimate to total widths of mesons. Our results are: $\Gamma [D_2^{\ast }(2460{)}^0]=51.3$ MeV and $\Gamma [D_{s2}^{\ast }(2573{)}^{+}]=19.6$ MeV. The ratios of branching ratios of two main channels are $Br[D_2^{\ast }(2460{)}^0\to D^{+}{\pi }^{-}]/Br[D_2^{\ast }(2460{)}^0\to D^{\ast +}{\pi }^{-}]=2.13$ and $Br[D_{s2}^{\ast }(2573{)}^{+}\to D^{\ast 0}{K}^{+}]/Br[D_{s2}^{\ast }(2573{)}^{+}\to D^0{K}^{+}]=0.08$, respectively.

   hep-phInt.J.Mod.Phys.A(2017)·8 citations
8. 08*

   Fully differential NLO predictions for the rare muon decay

   G. M. Pruna🇨🇭 · A. Signer🇨🇭 · Y. Ulrich🇨🇭

   Using the automation program GoSam, fully differential NLO corrections were obtained for the rare decay of the muon $\mu \to e\nu \bar{\nu }ee$. This process is an important Standard Model background to searches of the Mu3e collaboration for lepton-flavour violation, as it becomes indistinguishable from the signal $\mu \to 3e$ if the neutrinos carry little energy. With our NLO program we are able to compute the branching ratio as well as custom-tailored observables for the experiment. With minor modifications, related decays of the tau can also be computed.

   hep-phPLB(2017)·47 citations
9. 09*

   What antineutrinos can tell about octant and ${\delta }_{CP}$ in DUNE?

   Newton Nath🇮🇳 · Monojit Ghosh🇮🇳 · Srubabati Goswami🇮🇳

   We study the efficiency of DUNE, a next generation long baseline oscillation experiment to resolve two major unknowns in neutrino oscillation physics. These are, octant of ${\theta }_{23}$ (i.e. if ${\theta }_{23}$ is $<45^{\circ }$ or $>45^{\circ }$) and Dirac CP phase ${\delta }_{CP}$. We mainly focus on the role of antineutrinos when they travel 1300 km baseline of DUNE. We observe that for DUNE, the antineutrino runs help to remove parameter degeneracies even in the parameter space where the antineutrino probability suffers from various degeneracies. We study these points in detail and find that, due to enhanced matter effect longer baseline experiments create an increased tension between the neutrino and the antineutrino probabilities which helps to increase total sensitivity in case of combined runs. We also find that, antineutrino run increases overall CP sensitivity due to its ability to abolish octant-${\delta }_{CP}$ degeneracy.

   hep-phPoS(2016)·0 citations
10. 10*

    Interplay of soft and perturbative correlations in multiparton interactions at central rapidities

    B. Blok🇮🇱 · M. Strikman🇺🇸

    We study the role of soft/nonperturbative correlations in the multi parton interactions in the central kinematics relevant for double parton scattering (DPS) and underlying event (UE) measurements at ATLAS and CMS. We show that the effect of soft correlations is negligible for DPS regime (typical transverse momenta larger than 10-20 GeV), but may be important for UE (several GeV scale). The characteristic scale where soft correlations become important increases with decrease of $x$ (energy increase) leading to approximately constant \effs at small x.

    hep-phhep-exPLB(2017)·8 citations
11. 11*

    Torsion as a Dark Matter Candidate from the Higgs Portal

    Alexander S. Belyaev🇬🇧 · Ilya L. Shapiro🇧🇷 · Marc C. Thomas🇬🇧

    Torsion is a metric-independent component of gravitation, which may provide a more general geometry than the one taking place within general relativity. On the other hand torsion could lead to interesting phenomenology in both particle physics and cosmology. In the present work it is shown that a torsion field interacting with the SM Higgs doublet and having a negligible coupling to SM fermions is protected from decaying by a $Z_2$ symmetry, and therefore becomes a promising Dark Matter (DM) candidate. In order to check the consistency of this scenario we evaluate the DM relic density and explore direct DM detection and collider constraints on this model. It turns out that in the model when the Higgs boson is only partly responsible for the generation of torsion mass, there is a region of parameter space where torsion contributes 100% to the DM budget of the Universe. Furthermore, we show that the LHC currently has a limited sensitivity to the torsion parameter space via mono-jet signature and will be able to considerably improve its coverage of the torsion parameter space with the projected high luminosity.

    hep-phPRD(2017)·24 citations
12. 12*

    Chiral Thermodynamics in a finite box

    Ana Juričić🇦🇹 · Bernd-Jochen Schaefer🇩🇪

    Finite-volume modifications of the two-flavor chiral phase diagram are investigated within an effective quark-meson model in various mean-field approximations. The role of vacuum fluctuations and boundary conditions, their influence on higher cumulants and signatures of a possible pseudo-critical endpoint are amplified with smaller volumes.

    hep-phhep-thnucl-thActa Phys.Polon.Supp.(2017)·9 citations
13. 13*

    Global study of nuclear modifications on parton distribution functions

    Rong Wang🇨🇳 · Xurong Chen🇨🇳 · Qiang Fu🇨🇳

    A global analysis of nuclear medium modifications of parton distributions is presented using deeply inelastic scattering data of various nuclear targets. Two obtained data sets are provided for quark and gluon nuclear modification factors, referred as nIMParton16. One is from the global fit only to the experimental data of isospin-scalar nuclei (Set A), and the other is from the fit to all the measured nuclear data (Set B). The scale-dependence is described by DGLAP equations with nonlinear corrections in this work. The Fermi motion and off-shell effect, nucleon swelling, and parton-parton recombination are taken into account together for modeling the complicated $x$-dependence of nuclear modification. The nuclear gluon shadowing in this paper is dynamically generated by the QCD evolution of parton splitting and recombination processes with zero gluon density at the input scale. Sophisticated nuclear dependence of nuclear medium effects is studied with only two free parameters. With the obtained free parameters from the global analysis, the nuclear modifications of parton distribution functions of unmeasured nuclei can be predicted in our model. Nuclear modification of deuteron is also predicted and shown with recent measurement at JLab.

    hep-phNPB(2017)·46 citations
14. 14*

    Electromagnetic Properties of a Hot and Dense Medium

    Samina Masood🇺🇸

    We study the properties of an electromagnetically interacting medium in the presence of high concentration of electrons at extremely high temperatures and chemical potentials. We show that the electromagnetic properties of a medium such as the electric permittivity, magnetic permeability, magnetic moments and the propagation speed of electromagnetic waves as well as the corresponding particle processes depend on temperature and density of the medium. Electromagnetic properties of neutrinos are significantly modified due to their interactions with electrons when they propagate through such a medium of hot and dense electrons.

    hep-phPoS(2016)·0 citations
15. 15*

    Amplitudes ratios in ${\rho }^0$ leptoproductions and GPDs

    S.V. Goloskokov🇷🇺

    We investigate exclusive leptoproduction of ${\rho }^0$ meson. These reactions were analyzed within the factorizing handbag approach. In our model good agreement of observables for light meson production with experimental data in a wide energy range was found. Using the model results we calculate the ratio of different helicity amplitudes for a transversely polarized proton target to the leading twist longitudinal amplitude. Our results are close to the amplitude ratios measured by HERMES.

    hep-phEPJ Web Conf.(2017)·0 citations
16. 16*

    A quark model study of strong decays of $X\left(3915\right)$

    P. González🇪🇸

    Strong decays of $X\left(3915\right)$ are analyzed from two quark model descriptions of $X\left(3915\right)$, a conventional one in terms of the Cornell potential and an unconventional one from a Generalized Screened potential. We conclude that the experimental suppression of the OZI allowed decay $X\left(3915\right)\to D\overline{D}$ might be explained in both cases as due to the momentum dependence of the decay amplitude. However, the experimental significance of the OZI forbidden decay $X\left(3915\right)\to \omega J/\psi$ could favor an unconventional description.

    hep-phhep-exJ.Phys.G(2017)·6 citations
17. 17*

    Exclusive $J/\psi$ production at the LHC in the $k_T$ factorization approach

    S.P. Jones🇩🇪 · A.D. Martin🇬🇧 · M.G. Ryskin🇬🇧 · T. Teubner🇬🇧

    The recent LHCb data for exclusive $J/\psi$ peripheral production at 13 TeV motivate an improved `NLO' analysis to estimate the gluon distribution at low $x$ in which we re-calculate the rapidity gap survival factors and use a more precise expression for the photon flux. We comment on the difference between the $k_T$ and collinear factorization approaches.

    hep-phJ.Phys.G(2017)·38 citations
18. 18*

    Radiative decays of $1^{++}$ heavy mesons in the covariant light-front approach

    Yan-Liang Shi🇺🇸

    We calculate the predicted width for the radiative decay of a $1^{++}$ heavy meson via the channel $1^{++}\to 1^{--}+\gamma$ in the covariant light-front quark model. Specifically, we compute the decay widths for ${\chi }_{c1}(1P)\to J/\psi +\gamma$ and ${\chi }_{b1}(nP)\to {\rm Y}(n^{\prime }S)+\gamma$. The results are compared with experimental data and with predictions from calculations based on nonrelativistic models and their extensions to include relativistic effects.

    hep-ph2 citations
19. 19*

    Next-to-leading order prediction for the decay $\mu \to e(e^{+}{e}^{-})\nu \bar{\nu }$

    M. Fael🇨🇭 · C. Greub🇨🇭

    We present the differential decay rates and the branching ratios of the muon decay with internal conversion, $\mu \to e(e^{+}{e}^{-})\nu \bar{\nu }$, in the Standard Model at next-to-leading order (NLO) in the on-shell scheme. This rare decay mode of the muon is among the main sources of background to the search for $\mu \to eee$ decay. We found that in the phase space region where the neutrino energies are small, and the three-electron momenta have a similar signature as in the $\mu \to eee$ decay, the NLO corrections decrease the leading-order prediction by about $10-20\%$

    hep-phhep-exJHEP(2017)·45 citations
20. 20*

    Holographic Heavy-Light Chiral Effective Action

    Yizhuang Liu🇺🇸 · Ismail Zahed🇺🇸

    We propose a variant of the $D4$-$D8$ construction to describe the low energy effective theory of heavy-light mesons, interacting with the lowest lying pseudoscalar and vector mesons. The heavy degrees of freedom are identified with the $D{8}_L$-$D{8}_H$ string low energy modes, and are approximated near the world volume of $N_f-1$ light $D{8}_L$ branes, by fundamental vector field valued in $U(N_f-1)$. The effective action follows from the reduction of the bulk D-brane Born-Infeld (DBI) and Chern-Simons (CS) actions, and is shown to exhibit both chiral and heavy-quark symmetry. The action interpolates continuously between the $U(N_f)$ case with massless mesons, and the $U(N_f-1)$ case with heavy-light mesons. The heavy-light meson radial spectrum is Regge-like. The one-pion and two-pion couplings to the heavy-light multiplets are evaluated. The partial widths for the charged decays $G\to H+\pi$ are shown to be comparable to the recently reported full widths for both the charm and bottom mesons.

    hep-phhep-thnucl-thPRD(2017)·32 citations
21. 21*

    Superconformal Algebraic Approach to Hadron Structure

    Guy F. de Teramond🇨🇷 · Stanley J. Brodsky🇺🇸 · Alexandre Deur🇺🇸 · Hans Gunter Dosch🇩🇪 · Raza Sabbir Sufian🇺🇸

    Fundamental aspects of nonperturbative QCD dynamics which are not obvious from its classical Lagrangian, such as the emergence of a mass scale and confinement, the existence of a zero mass bound state, the appearance of universal Regge trajectories and the breaking of chiral symmetry are incorporated from the onset in an effective theory based on superconformal quantum mechanics and its embedding in a higher dimensional gravitational theory. In addition, superconformal quantum mechanics gives remarkable connections between the light meson and nucleon spectra. This new approach to hadron physics is also suitable to describe nonperturbative QCD observables based on structure functions, such as GPDs, which are not amenable to a first-principle computation. The formalism is also successful in the description of form factors, the nonperturbative behavior of the strong coupling and diffractive processes. We also discuss in this article how the framework can be extended rather successfully to the heavy-light hadron sector.

    hep-phhep-thEPJ Web Conf.(2017)·12 citations
22. 22*

    Bound state structure and electromagnetic form factor beyond the ladder approximation

    V. Gigante🇧🇷 · J. H. Alvarenga Nogueira🇧🇷 · E. Ydrefors🇧🇷 · C. Gutierrez🇧🇷 · V.A. Karmanov🇷🇺 · T. Frederico🇧🇷

    We investigate the response of the bound state structure of a two-boson system, within a Yukawa model with a scalar boson exchange, to the inclusion of the cross-ladder contribution to the ladder kernel of the Bethe-Salpeter equation. The equation is solved by means of the Nakanishi integral representation and light-front projection. The valence light-front wave function and the elastic electromagnetic form factor beyond the impulse approximation, with the inclusion of the two-body current, generated by the cross-ladder kernel, are computed. The valence wave function and electromagnetic form factor, considering both ladder and ladder plus cross-ladder kernels, are studied in detail. Their asymptotic forms are found to be quite independent of the inclusion of the cross-ladder kernel, for a given binding energy. The asymptotic decrease of form factor agrees with the counting rules. This analysis can be generalized to fermionic systems, with a wide application in the study of the meson structure.

    hep-phnucl-thPRD(2017)·15 citations
23. 23*

    Prompt neutrino fluxes in the atmosphere with PROSA parton distribution functions

    PROSA Collaboration: M.V. Garzelli🇩🇪 · S. Moch🇩🇪 · O. Zenaiev🇩🇪 · A. Cooper-Sarkar🇬🇧 · A. Geiser🇩🇪 · K. Lipka🇩🇪 · R. Placakyte🇩🇪 · G. Sigl🇩🇪

    Effects on atmospheric prompt neutrino fluxes of present uncertainties affecting the nucleon composition are studied by using the PROSA fit to parton distribution functions (PDFs). The PROSA fit extends the precision of the PDFs to low x, which is the kinematic region of relevance for high-energy neutrino production, by taking into account LHCb data on charm and bottom hadroproduction. In the range of neutrino energies explored by present Very Large Volume Neutrino Telescopes, it is found that PDF uncertainties are far smaller with respect to those due to renormalization and factorization scale variation and to assumptions on the cosmic ray composition, which at present dominate and limit our knowledge of prompt neutrino fluxes. A discussion is presented on how these uncertainties affect the expected number of atmospheric prompt neutrino events in the analysis of high-energy events characterized by interaction vertices fully contained within the instrumented volume of the detector, performed by the IceCube collaboration.

    hep-phJHEP(2017)·64 citations
24. 24*

    Radiation and the classical double copy for color charges

    Walter D. Goldberger🇺🇸 · Alexander K. Ridgway🇺🇸

    We construct perturbative classical solutions of the Yang-Mills equations coupled to dynamical point particles carrying color charge. By applying a set of color to kinematics replacement rules first introduced by Bern, Carrasco and Johansson (BCJ), these are shown to generate solutions of d-dimensional dilaton gravity, which we also explicitly construct. Agreement between the gravity result and the gauge theory double copy implies a correspondence between non-Abelian particles and gravitating sources with dilaton charge. When the color sources are highly relativistic, dilaton exchange decouples, and the solutions we obtain match those of pure gravity. We comment on possible implications of our findings to the calculation of gravitational waveforms in astrophysical black hole collisions, directly from computationally simpler gluon radiation in Yang-Mills theory.

    ↳ hep-thgr-qchep-phPRD(2017)·302 citations
25. 25*

    On the Quantisation of Complex Higher Derivative Theories and Avoiding the Ostrogradsky Ghost

    Martti Raidal🇪🇪 · Hardi Veermäe🇪🇪

    Generic higher derivative theories are believed to be fundamentally unphysical because they contain Ostrogradsky ghosts. We show that within complex classical mechanics it is possible to construct higher derivative theories that circumvent the Ostrogradsky theorem and have a real energy spectrum that is bounded from below. The complex theory can be canonically quantised. The resulting quantum theory does not suffer from the kinetic instability and maintains the usual probabilistic interpretation without violating the correspondence principle. As a proof of concept, we construct a class of stable interacting complex higher derivative theories. This consistent and canonical framework allows us to analyse previous attempts to avoid the ghosts that use non-canonical quantisation schemes, such as the Lee-Wick theories, Dirac-Pauli quantisation or PT-symmetric quantum mechanics. The key to understand the would-be ghosts in any kinetically stable higher derivative theory is to accept the complex system behind it.

    ↳ hep-thhep-phquant-phNPB(2017)·69 citations
26. 26*

    Scale-setting, flavour dependence and chiral symmetry restoration

    Daniele Binosi🇮🇹 · Craig D. Roberts🇺🇸 · Jose Rodriguez-Quintero🇪🇸

    We determine the flavour dependence of the renormalisation-group-invariant running interaction through judicious use of both unquenched Dyson-Schwinger equation and lattice results for QCD's gauge-sector two-point functions. An important step is the introduction of a physical scale setting procedure that enables a realistic expression of the effect of different numbers of active quark flavours on the interaction. Using this running interaction in concert with a well constrained class of dressed--gluon-quark vertices, we estimate the critical number of active lighter-quarks above which dynamical chiral symmetry breaking becomes impossible: $n_f^{\mathrm{cr}}\approx 9$; and hence in whose neighbourhood QCD is plausibly a conformal theory.

    ↳ nucl-thhep-lathep-phPRD(2017)·56 citations
27. 27*

    Cross-correlation of weak lensing and gamma rays: implications for the nature of dark matter

    Tilman Tröster🇨🇦 · Stefano Camera🇬🇧 · Mattia Fornasa🇳🇱 · Marco Regis🇮🇹 · Ludovic van Waerbeke🇨🇦 · Joachim Harnois-Déraps🇬🇧 · Shin'ichiro Ando🇳🇱 · Maciej Bilicki🇳🇱 · Thomas Erben🇩🇪 · Nicolao Fornengo🇮🇹 · Catherine Heymans🇬🇧 · Hendrik Hildebrandt🇩🇪 and 3 other authors

    We measure the cross-correlation between Fermi-LAT gamma-ray photons and over 1000 deg${}^2$ of weak lensing data from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), the Red Cluster Sequence Lensing Survey (RCSLenS), and the Kilo Degree Survey (KiDS). We present the first measurement of tomographic weak lensing cross-correlations and the first application of spectral binning to cross-correlations between gamma rays and weak lensing. The measurements are performed using an angular power spectrum estimator while the covariance is estimated using an analytical prescription. We verify the accuracy of our covariance estimate by comparing it to two internal covariance estimators. Based on the non-detection of a cross-correlation signal, we derive constraints on weakly interacting massive particle (WIMP) dark matter. We compute exclusion limits on the dark matter annihilation cross-section \langle\sigma_\rm{ann} v \rangle, decay rate \Gamma_\rm{dec}, and particle mass m_\rm{DM}. We find that in the absence of a cross-correlation signal, tomography does not significantly improve the constraining power of the analysis. Assuming a strong contribution to the gamma-ray flux due to small-scale clustering of dark matter and accounting for known astrophysical sources of gamma rays, we exclude the thermal relic cross-section for particle masses of m_\rm{DM}\lesssim 20 GeV.

    ↳ astro-ph.COhep-phMNRAS(2017)·47 citations
28. 28*

    A Novel Algorithm for Extracting the Parton Distribution Amplitude from the Euclidean Bethe-Salpeter Wave Function

    Fei Gao🇨🇳 · Lei Chang🇨🇳 · Yu-xin Liu🇨🇳

    We propose a new numerical method to compute parton distribution amplitude(PDA) from the Euclidean Bethe-Salpeter wave function. The essential step is to extract the weight function in the Nakanishi representation of the Bethe-Salpeter wave function in Euclidean space, which is an ill-posed inversion problem, via the maximum entropy method(MEM). The Nakanishi weight function as well as the corresponding light-front PDA can be well determined. We confirm the previous works on PDA computation therein the different method has been performed.

    ↳ nucl-thhep-phPLB(2017)·26 citations
29. 29*

    Search for Flavor Changing Neutral Current in Top Production and Decays

    Tae Jeong Kim (for the CMS collaboration)🇰🇷

    Searches for flavor changing neutral currents in top production and decay using data collected by the Compact Muon Solenoid (CMS) experiment at $\sqrt{s}$ = 7 and 8 TeV are presented, corresponding to an integrated luminosity of around 5 fb${}^{-1}$ and 20 fb${}^{-1}$. FCNC searches are conducted to probe $tqZ$, $tq\gamma$, $tqH$, and $tgq$ interactions in various channels. By the time of the 38${}^{th}$ ICHEP conference in 2016, the upper limits on $\mathcal{B}(t\to u\gamma )$ $<$ 0.013%, $\mathcal{B}(t\to ug)$ $<$ 0.036%, $\mathcal{B}(t\to uZ)$ $<$ 0.05% and $\mathcal{B}(t\to uH)$ $<$ 0.42% at the 95% confidence level had been obtained by the CMS collaboration.

    ↳ hep-exhep-phPoS(2016)·1 citation
30. 30*

    Gluon and Ghost Dynamics from Lattice QCD

    O. Oliveira🇵🇹 · A. G. Duarte🇵🇹 · D. Dudal🇧🇪 · P. J. Silva🇵🇹

    The two point gluon and ghost correlation functions and the three gluon vertex are investigated, in the Landau gauge, using lattice simulations. For the two point functions, we discuss the approach to the continuum limit looking at the dependence on the lattice spacing and volume. The analytical structure of the propagators is also investigated by computing the corresponding spectral functions using an implementation of the Tikhonov regularisation to solve the integral equation. For the three point function we report results when the momentum of one of the gluon lines is set to zero and discuss its implications.

    ↳ hep-lathep-phhep-thnucl-thFew Body Syst.(2017)·9 citations
31. 31*

    Classification of inflationary models and constraints on fundamental physics

    Mauro Pieroni🇫🇷

    This work is focused on the study of early time cosmology and in particular on the study of inflation. After an introduction on the standard Big Bang theory, we discuss the physics of CMB and we explain how its observations can be used to set constraints on cosmological models. We introduce inflation and we carry out its simplest realization by presenting the observables and the experimental constraints that can be set on inflationary models. The possibility of observing primordial gravitational waves (GWs) produced during inflation is discussed. We present the reasons to define a classification of inflationary models and introduce the \beta-function formalism for inflation by explaining why in this framework we can naturally define a set of universality classes for inflationary models. Theoretical motivations to support the formulation of inflation in terms of this formalism are presented. Some generalized models of inflation are introduced and the extension of the \beta-function formalism for inflation to these models is discussed. Finally we focus on the study of models where the (pseudo-scalar) inflaton is coupled to some Abelian gauge fields that can be present during inflation. The analysis of the problem is carried out by using a characterization of inflationary models in terms of their asymptotic behavior. A wide set of theoretical aspects and of observational consequences is discussed.

    ↳ gr-qcastro-ph.COhep-ph6 citations
32. 32*

    Finite volume corrections and low momentum cuts in the thermodynamics of quantum gases

    Krzysztof Redlich (Wroclaw U)🇵🇱 · Kacper Zalewski (Cracow, INP & Jagiellonian U.)🇵🇱

    The conjecture, that the finite volume corrections to the thermodynamic functions can be correctly reproduced by using the thermodynamic limit with low particle momenta cutoff is examined in a very transparent example of an ideal boson gas in one dimension. We show that this conjecture is always true in principle, and derive convenient relations for the momentum cutoff dependence on thermal parameters in the asymptotic limits of large and small volume.

    ↳ nucl-thhep-ph13 citations
33. 33*

    Perturbations of ultralight vector field dark matter

    J. A. R. Cembranos🇪🇸 · A. L. Maroto🇪🇸 · S. J. Núñez Jareño🇪🇸

    We study the dynamics of cosmological perturbations in models of dark matter based on ultralight coherent vector fields. Very much as for scalar field dark matter, we find two different regimes in the evolution: for modes with $k^2\ll \mathcal{H}ma$, we have a particle-like behaviour indistinguishable from cold dark matter, whereas for modes with $k^2\gg \mathcal{H}ma$, we get a wave-like behaviour in which the sound speed is non-vanishing and of order $c_s^2\simeq k^2/m^2{a}^2$. This implies that, also in these models, structure formation could be suppressed on small scales. However, unlike the scalar case, the fact that the background evolution contains a non-vanishing homogeneous vector field implies that, in general, the evolution of the three kinds of perturbations (scalar, vector and tensor) can no longer be decoupled at the linear level. More specifically, in the particle regime, the three types of perturbations are actually decoupled, whereas in the wave regime, the three vector field perturbations generate one scalar-tensor and two vector-tensor perturbations in the metric. Also in the wave regime, we find that a non-vanishing anisotropic stress is present in the perturbed energy-momentum tensor giving rise to a gravitational slip of order $(\Phi -\Psi )/\Phi \sim c_s^2$. Moreover in this regime the amplitude of the tensor to scalar ratio of the scalar-tensor modes is also $h/\Phi \sim c_s^2$. This implies that small-scale density perturbations are necessarily associated to the presence of gravity waves in this model. We compare their spectrum with the sensitivity of present and future gravity waves detectors.

    ↳ astro-ph.COgr-qchep-phJHEP(2017)·37 citations
34. 34*

    Effective field theory for magnetic compactifications

    Wilfried Buchmuller🇩🇪 · Markus Dierigl🇩🇪 · Emilian Dudas🇫🇷 · Julian Schweizer🇩🇪

    Magnetic flux plays an important role in compactifications of field and string theories in two ways, it generates a multiplicity of chiral fermion zero modes and it can break supersymmetry. We derive the complete four-dimensional effective action for N=1 supersymmetric Abelian and non-Abelian gauge theories in six dimensions compactified on a torus with flux. The effective action contains the tower of charged states and it accounts for the mass spectrum of bosonic and fermionic fields as well as their level-dependent interactions. This allows us to compute quantum corrections to the mass and couplings of Wilson lines. We find that the one-loop corrections vanish, contrary to the case without flux. This can be traced back to the spontaneous breaking of a symmetry of the six-dimensional theory by the background gauge field, with the Wilson line as Goldstone boson.

    ↳ hep-thhep-phJHEP(2017)·35 citations
35. 35*

    Extragalactic photon-ALP conversion at CTA energies

    A. Kartavtsev🇩🇪 · G. Raffelt🇩🇪 · H. Vogel🇩🇪

    Magnetic fields in extragalactic space between galaxy clusters may induce conversions between photons and axion-like particles (ALPs), thereby shielding the photons from absorption on the extragalactic background light. For TeV gamma rays, the oscillation length ($l_{\mathrm{osc}}$) of the photon-ALP system becomes inevitably of the same order as the coherence length of the magnetic field ($l$) and the length over which the field changes significantly (transition length $l_{\mathrm{t}}$) due to refraction on background photons. We derive exact statistical evolution equations for the mean and variance of the photon and ALP transfer functions in the non-adiabatic regime ($l_{\mathrm{osc}}\sim l\gg l_{\mathrm{t}}$). We also make analytical predictions for the transfer functions in the quasi-adiabatic regime ($l_{\mathrm{osc}}\ll l,l_{\mathrm{t}}$). Our results are important in light of the upcoming Cherenkov Telescope Array (CTA), and may also be applied to models with non-zero ALP masses.

    ↳ astro-ph.HEhep-phJCAP(2017)·50 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.