Fri·Aug 11, 2017Friday·August 11, 2017

1. 01*

   Super-light baryphotons, Weak Gravity Conjecture and Exotic instantons in Neutron-Antineutron transitions

   Andrea Addazi🇨🇳

   In companion papers \cite{Addazi:2015pia,Addazi:2016rgo}, we have discussed current bounds of a new super-light baryo-photon, associated to a $U(1{)}_{B-L}$ gauged, from neutron-antineutron current data, which are competitive with Eötvös type experiments. Here, we discuss the implications of a possible baryo-photon detection in string theory and quantum gravity. The discovery of a very light gauge boson should imply the violation of the Weak Gravity Conjecture, carrying deep consequences in our understanding of holography, quantum gravity and black holes. On the other hand, we show how the detection of a baryo-photon would also exclude the generation of all $B-L$ violating operators from Exotic Stringy Instantons. We will disclaim the common statement in literature that neutron-antineutron may indirectly test at least a $300-1000\mathrm{TeV}$ scale. Searches of baryo-photons can provide indirect informations of the Planck (or String) scale (quantum black holes, holography and non-perturbative stringy effects). This strongly motivates new neutron-antineutron experiments with adjustable magnetic fields dedicated to the detection of super-light baryo-photons.

   hep-phgr-qchep-thCPC(2018)·4 citations
2. 02*

   Probing the neutrino mass ordering with KM3NeT-ORCA: Analysis and perspectives

   Francesco Capozzi🇺🇸 · Eligio Lisi🇮🇹 · Antonio Marrone🇮🇹

   The discrimination of the two possible options for the neutrino mass ordering (normal or inverted) is a major goal for current and future neutrino oscillation experiments. Such goal might be reached by observing high-statistics energy-angle spectra of events induced by atmospheric neutrinos and antineutrinos propagating in the Earth matter. Large volume water-Cherenkov detectors envisaged to this purpose include the so-called KM3NeT-ORCA project (in seawater) and the IceCube-PINGU project (in ice). Building upon a previous work focused on PINGU, we study in detail the effects of various systematic uncertainties on the ORCA sensitivity to the mass ordering, for the reference configuration with 9 m vertical spacing. We point out the need to control spectral shape uncertainties at the percent level, the effects of better priors on the theta-23 mixing parameter, and the benefits of an improved flavor identification in reconstructed ORCA events.

   hep-phhep-exJ.Phys.G(2018)·13 citations
3. 03*

   General formulae for dipole Wilson line correlators with the Color Glass Condensate

   Kenji Fukushima🇯🇵 · Yoshimasa Hidaka🇯🇵

   We present general formulae to compute Wilson line correlators with the Color Glass Condensate described by the McLerran-Venugopalan model. We explicitly construct a complete and non-orthogonal set of color-singlet bases and write matrix elements down, so that the exponential of the matrix leads to the Wilson line correlators. We further develop a systematic perturbative expansion of dipole Wilson line correlators in terms of $1/N_c$ where $N_c$ is the color number. As a phenomenological application we calculate the flow harmonics $v_n\{m\}$ in the dipole model and discuss the $N_c$ scaling.

   hep-phhep-thJHEP(2017)·20 citations
4. 04*

   Electroweak Sphaleron with Dimension-6 Operators

   Xucheng Gan🇺🇸 · Andrew J. Long🇺🇸 · Lian-Tao Wang🇺🇸

   New physics at the TeV scale can affect the dynamics of the electroweak phase transition in many ways. In this note, we evaluate its impact on the rate of baryon-number violation via sphaleron transitions. We parameterize the effect of new physics with dimension-6 operators, and we use the Newton-Kantorovich method to numerically solve the resulting equations of motion. Depending on the sign of the coefficient of the dimension-6 operators, their presence can either increase or decrease the sphaleron energy at the level of a few percent, parametrically of order $m_W^2/{\Lambda }^2$ where $\Lambda$ is the scale suppressing the dimension-6 operator. The baryon-number washout condition, typically written as $v_c/T_c>1$, is directly proportional to the sphaleron energy, and we discuss how the presence of dimension-6 operators can affect electroweak baryogenesis.

   hep-phastro-ph.COhep-thPRD(2017)·42 citations
5. 05*

   Cross sections for inelastic meson-meson scattering

   Kai Yang🇨🇳 · Xiao-Ming Xu🇨🇳 · H. J. Weber🇺🇸

   We study two kinds of inelastic meson-meson scattering. The first kind is inelastic 2-to-2 meson-meson scattering that is governed by quark interchange as well as quark-antiquark annihilation and creation. Cross-section formulas are provided to get unpolarized cross sections for $\pi K\to \rho K^{\ast }$ for $I=1/2$, $\pi K^{\ast }\to \rho K$ for $I=1/2$, $\pi K^{\ast }\to \rho K^{\ast }$ for $I=1/2$, and $\rho K\to \rho K^{\ast }$ for $I=1/2$. Near threshold, quark interchange dominates the reactions near the critical temperature. The second kind is 2-to-1 meson-meson scattering with the process that a quark in an initial meson and an antiquark in another initial meson annihilate into a gluon and subsequently the gluon is absorbed by the other antiquark or quark. The transition potential for the process is derived. Four Feynman diagrams at tree level contribute to the 2-to-1 meson-meson scattering. Starting from the $S$-matrix element, the isospin-averaged unpolarized cross section with transition amplitudes is derived. The cross sections for $\pi \pi \to \rho$ and $\pi K\to K^{\ast }$ decrease with increasing temperature.

   hep-phnucl-thPRD(2017)·7 citations
6. 06*

   Ma-xion: Majoron as QCD axion in a radiative seesaw model

   Ernest Ma🇺🇸 · Takahiro Ohata🇯🇵 · Koji Tsumura🇯🇵

   The smallness of neutrino mass, the strong CP problem, and the existence of dark matter are explained in an economical way. The neutrino mass is generated by the colored version of a radiative seesaw mechanism by using color adjoint mediators. The Majorana mass term of the adjoint fermion, which carries lepton number U(1)_L, is induced by its spontaneous breaking, resulting in a Majoron which doubles as the QCD (quantum chromodynamics) axion, thereby solving the strong CP problem. The breaking of U(1)_L sets simultaneously the seesaw scale for neutrino mass and the Peccei-Quinn breaking scale. This axion is a good candidate for dark matter as usually assumed.

   hep-phPRD(2017)·29 citations
7. 07*

   Charmed Axial Vector and Pseudoscalar Mesons Emitting Decays of Bottom Meson in NRQM

   Neelesh Sharma🇮🇳 · Rohit Dhir🇮🇳

   Two body nonleptonic weak decays of bottom mesons to a pseudoscalar meson and an axial-vector meson involving charmed states are studied using the non-relativistic quark model. We calculate the branching ratios of these decays by employing the factorization hypothesis. Obtained results are in good agreement with the existing experimental data. We also calculated the branching ratios in the light of heavy quark symmetry constraints and compared with the exiting theoretical analyses.

   hep-ph0 citations
8. 08*

   $\rho$-Meson Form Factors in the Point Form

   Elmar P. Biernat🇵🇹 · Wolfgang Schweiger🇦🇹

   We present a calculation of the electromagnetic form factors of the ${\rho }^{+}$ meson. Our formalism is based on the point-form of relativistic quantum mechanics. Electron-$\rho$-meson scattering is formulated as a coupled-channel problem for a Bakamjian-Thomas mass operator, such that the dynamics of the exchanged photon is taken explicitly into account. The $\rho$-meson current is extracted from on-shell matrix elements of the optical potential of the scattering process. As a consequence of the violation of cluster separability in the Bakamjian-Thomas framework, our current includes additional, unphysical contributions, which can be separated from the physical ones uniquely. Our results for the form factors are in good agreement with other approaches.

   hep-phnucl-thActa Phys.Polon.Supp.(2017)·1 citation
9. 09*

   Strong decays of excited vector mesons

   M. Piotrowska🇵🇱 · F. Giacosa🇩🇪

   We study two nonets of excited vector mesons, predominantly corresponding to radially excited vector mesons with quantum numbers $n{}^{2S+1}{L}_J$ $=2^3{S}_1$ and to orbitally excited vector mesons with quantum numbers $n{}^{2S+1}{L}_J=1^3{D}_1$. We evaluate two types of decays of these mesons: into two pseudoscalar mesons and into a pseudoscalar and a ground-state vector meson. We compare the results with experimental data taken from PDG. We also make predictions for the strange-antistrange state in the $1^3{D}_1$ nonet denoted as $\varphi (1930)$, which has not yet been discovered.

   hep-phActa Phys.Polon.Supp.(2017)·1 citation
10. 10*

    Neutrino mass with large $SU(2{)}_L$ multiplet fields

    Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

    We propose an extension of the standard model introducing large $SU(2{)}_L$ multiplet fields which are quartet and septet scalars and quintet Majorana fermions. These multiplets can induce the neutrino masses via interactions with the $SU(2)$ doublet leptons. We then find the neutrino masses are suppressed by small vacuum expectation value of the quartet/septet and an inverse of quintet fermion mass relaxing the Yukawa hierarchies among the standard model fermions. We also discuss collider physics at the Large Hadron Collider considering production of charged particles in these multiplets, and due to effects of violating custodial symmetry, some specific signatures can be found. Then we discuss the detectability of these signals.

    hep-phPRD(2017)·19 citations
11. 11*

    Antimatter, Lorentz Symmetry, and Gravity

    Jay D. Tasson🇺🇸

    A brief introduction to the Standard-Model Extension (SME) approach to testing CPT and Lorentz symmetry is provided. Recent proposals for tests with antimatter are summarized, including gravitational and spectroscopic tests.

    hep-phJPS Conf.Proc.(2017)·4 citations
12. 12*

    Collinear and TMD Quark and Gluon Densities from Parton Branching Solution of QCD Evolution Equations

    F. Hautmann🇬🇧 · H. Jung🇩🇪 · A. Lelek🇩🇪 · V. Radescu🇨🇭 · R. Zlebcik🇩🇪

    We study parton-branching solutions of QCD evolution equations and present a method to construct both collinear and transverse momentum dependent (TMD) parton densities from this approach. We work with next-to-leading-order (NLO) accuracy in the strong coupling. Using the unitarity picture in terms of resolvable and non-resolvable branchings, we analyze the role of the soft-gluon resolution scale in the evolution equations. For longitudinal momentum distributions, we find agreement of our numerical calculations with existing evolution programs at the level of better than 1 percent over a range of five orders of magnitude both in evolution scale and in longitudinal momentum fraction. We make predictions for the evolution of transverse momentum distributions. We perform fits to the high-precision deep inelastic scattering (DIS) structure function measurements, and we present a set of NLO TMD distributions based on the parton branching approach.

    hep-phJHEP(2018)·189 citations
13. 13*

    Cornering the revamped BMV model with neutrino oscillation data

    Sabya Sachi Chatterjee🇮🇳 · Mehedi Masud🇪🇸 · Pedro Pasquini🇧🇷 · J.W.F. Valle🇪🇸

    Using the latest global determination of neutrino oscillation parameters from~\cite{deSalas:2017kay} we examine the status of the simplest revamped version of the BMV (Babu-Ma-Valle) model, proposed in~\cite{Morisi:2013qna}. The model predicts a striking correlation between the "poorly determined" atmospheric angle ${\theta }_{23}$ and CP phase ${\delta }_{CP}$, leading to either maximal CP violation or none, depending on the preferred ${\theta }_{23}$ octants. We determine the allowed BMV parameter regions and compare with the general three-neutrino oscillation scenario. We show that in the BMV model the higher octant is possible only at $99\%$ C.L., a stronger rejection than found in the general case. By performing quantitative simulations of forthcoming DUNE and T2HK experiments, using only the four "well-measured" oscillation parameters and the indication for normal mass ordering, we also map out the potential of these experiments to corner the model. The resulting global sensitivities are given in a robust form, that holds irrespective of the true values of the oscillation parameters.

    hep-phhep-exPLB(2017)·20 citations
14. 14*

    Two-photon exchange contribution to elastic $e^{-}$-proton scattering: Full dispersive treatment of $\pi N$ states and comparison with data

    O. Tomalak🇩🇪 · B. Pasquini🇮🇹 · M. Vanderhaeghen🇩🇪

    We evaluate the two-photon exchange correction to the elastic electron-proton scattering cross section within a dispersive framework. Besides the elastic contribution, we account for all $\pi N$ intermediate state contributions using the phenomenological MAID fit as an input. We develop a novel method for the analytical continuation of the two-photon exchange amplitudes into the unphysical region and generalize our previous work to the momentum transfer region $0.064{\mathrm{GeV}}^2\lesssim Q^2\lesssim 1{\mathrm{GeV}}^2$. We compare our results with recent OLYMPUS, CLAS and VEPP-3 data as well as with empirical fits and estimates in the forward angular region.

    hep-phnucl-exnucl-thPRD(2017)·43 citations
15. 15*

    An NLO QCD effective field theory analysis of $W_{}^{+}{W}_{}^{-}$ production at the LHC including fermionic operators

    Julien Baglio🇩🇪 · Sally Dawson🇺🇸 · Ian M. Lewis🇺🇸

    We study the impact of anomalous gauge boson and fermion couplings on the production of $W^{+}{W}^{-}$ pairs at the LHC. Helicity amplitudes are presented separately to demonstrate the sources of new physics contributions and the impact of QCD and electroweak corrections. The QCD corrections have important effects on the fits to anomalous couplings, in particular when one $W$ boson is longitudinally polarized and the other is transversely polarized. In effective field theory language, we demonstrate that the dimension-6 approximation to constraining new physics effects in $W^{+}{W}^{-}$ pair production fails at $p_T\sim 500-1000$ GeV.

    hep-phPRD(2017)·91 citations
16. 16*

    Radiative decays of the doubly charmed baryons in chiral perturbation theory

    Hao-Song Li🇨🇳 · Lu Meng🇨🇳 · Zhan-Wei Liu🇨🇳 · Shi-Lin Zhu🇨🇳

    We have systematically investigated the spin-$\frac{3}{2}$ to spin-$\frac{1}{2}$ doubly charmed baryon transition magnetic moments to the next-to-next-to-leading order in the heavy baryon chiral perturbation theory (HBChPT). Numerical results of transition magnetic moments and decay widths are presented to the next-to-leading order: ${\mu }_{{\Xi }_{cc}^{\ast ++}\to {\Xi }_{cc}^{++}}=-2.35{\mu }_N$, ${\mu }_{{\Xi }_{cc}^{\ast +}\to {\Xi }_{cc}^{+}}=1.55{\mu }_N$, ${\mu }_{{\Omega }_{cc}^{\ast +}\to {\Omega }_{cc}^{+}}=1.54{\mu }_N$, ${\Gamma }_{{\Xi }_{cc}^{\ast ++}\to {\Xi }_{cc}^{++}}=22.0$ keV, ${\Gamma }_{{\Xi }_{cc}^{\ast +}\to {\Xi }_{cc}^{+}}=9.57$ keV, ${\Gamma }_{{\Omega }_{cc}^{\ast +}\to {\Omega }_{cc}^{+}}=9.45$ keV.

    hep-phhep-exhep-latnucl-thPLB(2018)·87 citations
17. 17*

    The photon PDF determination within the xFitter framework

    Francesco Giuli🇬🇧

    The xFitter project (former HERAFitter project) is an open-source package that provides a framework for the determination of the parton distribution functions (PDFs) of the proton for many different kinds of analyses in Quantum Chromodynamics (QCD). xFitter version 2.0.0 has recently been released, and offers an expanded set of tools and options. It incorporates experimental data from a wide range of experiments including fixed-target, Tevatron, HERA, and LHC. xFitter can analyze this data up to next-to-next-to-leading-order (NNLO) in perturbation theory with a variety of theoretical calculations including numerous methodological options for carrying out PDF fits and plotting tools which help visualise the results. In this contribution, a determination of the photon PDF from fits to recent ATLAS measurements of high-mass Drell-Yan dilepton production at $\sqrt{s}$ = 8 TeV using this framework is presented. The work presented here is based on the paper published here: Eur.Phys.J. C77 (2017) no.6, 400

    hep-phPoS(2017)·0 citations
18. 18*

    A rapid holographic phase transition with brane-localized curvature

    Barry M. Dillon🇬🇧 · Basem Kamal El-Menoufi🇬🇧 · Stephan J. Huber🇬🇧 · Jonathan P. Manuel🇬🇧

    We study the finite-temperature properties of the Randall-Sundrum model in the presence of brane-localized curvature. At high temperature, as dictated by AdS/CFT, the theory is in a confined phase dual to the planar AdS black hole. When the radion is stabilized, à la Goldberger-Wise, a holographic first-order phase transition proceeds. The brane-localized curvature contributes to the radion kinetic energy, substantially decreasing the critical bubble energy. Contrary to previous results, the phase transition completes at much larger values of $N$, the number of degrees of freedom in the CFT. Moreover, the field value of the bulk scalar on the TeV-brane is allowed to become large, while remaining consistent with back-reaction constraints. Assisted by this fact, we find that for a wide region in the parameter space tunneling happens rather quickly, i.e. the nucleation temperature becomes of the order of the critical temperature. At zero temperature, the most important signature of brane-localized curvature is the reduction of spin-2 Kaluza-Klein graviton masses and a heavier radion.

    ↳ hep-thhep-phPRD(2018)·57 citations
19. 19*

    Time-integrated directional detection of dark matter

    Ciaran A. J. O'Hare🇬🇧 · Bradley J. Kavanagh🇫🇷 · Anne M. Green🇬🇧

    The analysis of signals in directional dark matter (DM) detectors typically assumes that the directions of nuclear recoils can be measured in the Galactic rest frame. However, this is not possible with all directional detection technologies. In nuclear emulsions, for example, the recoil events must be detected and measured after the exposure time of the experiment. Unless the entire detector is mounted and rotated with the sidereal day, the recoils cannot be reoriented in the Galactic rest frame. We examine the effect of this `time integration' on the primary goals of directional detection, namely: (1) confirming that the recoils are anisotropic; (2) measuring the median recoil direction to confirm their Galactic origin; and (3) probing below the neutrino floor. We show that after time integration the DM recoil distribution retains a preferred direction and is distinct from that of Solar neutrino-induced recoils. Many of the advantages of directional detection are therefore preserved and it is not crucial to mount and rotate the detector. Rejecting isotropic backgrounds requires a factor of 2 more signal events compared with an experiment with event time information, whereas a factor of 1.5-3 more events are needed to measure a median direction in agreement with the expectation for DM. We also find that there is still effectively no neutrino floor in a time-integrated directional experiment. However to reach a cross section an order of magnitude below the floor, a factor of 8 larger exposure is required than with a conventional directional experiment. We also examine how the sensitivity is affected for detectors with only 2D recoil track readout, and/or no head-tail measurement. As for non-time-integrated experiments, 2D readout is not a major disadvantage, though a lack of head-tail sensitivity is.

    ↳ astro-ph.COhep-phPRD(2017)·32 citations
20. 20*

    Do photons travel faster than gravitons?

    Damian Ejlli🇷🇺

    The vacuum polarization in an external gravitational field due to one loop electron-positron pair and one loop millicharged fermion-antifermion pair is studied. Considering the propagation of electromagnetic (EM) radiation and gravitational waves (GWs) in an expanding universe, it is shown that by taking into account QED effects in curved spacetime, the propagation velocity of photons is superluminal and can exceed that of gravitons. We apply these results to the case of the GW170817 event detected by LIGO. If the EM radiation and GWs are emitted either simultaneously or with a time difference from the same source, it is shown that the EM radiation while propagating with superluminal velocity, would be detected either in advance or in delay with respect to GW depending on the ratio of millicharged fermion relative charge to mass $ϵ/m_{ϵ}$.

    ↳ gr-qcastro-ph.COhep-phJCAP(2018)·0 citations
21. 21*

    Light of Planck-2015 on Non-Canonical Inflation

    Kh. Saaidi🇮🇷 · A. Mohammadi🇮🇷 · T. Golanbari🇮🇷

    Slow-roll inflationary scenario is considered in non-canonical scalar field model supposing a power-law function for kinetic term, and using two formalisms. In the first approach, the potential is considered as a power-law function, that is the most common approach in studying inflation. Hamilton-Jacobi approach is selected as the second formalism, so that the Hubble parameter is introduced as a function of scalar field instead of the potential. Employing the last observational data, the free parameters of the model are constrained, and the predicted form of the potential and attractor behavior of the model are considered in detail.

    ↳ gr-qchep-phAdv.High Energy Phys.(2015)·21 citations
22. 22*

    Intermediate inflation driven by DBI scalar field

    N. Nazavari🇮🇷 · A. Mohammadi🇮🇷 · Z. Ossoulian🇮🇷 · Kh. Saaidi🇮🇷

    Picking out DBI scalar field as inflation, the slow-rolling inflationary scenario is studied by attributing an exponential time function to scale factor; known as intermediate inflation. The perturbation parameters of the model are estimated numerically for two different cases and the final result is compared with Planck data. The diagram of tensor-to-scalar ratio $r$ versus scalar spectra index $n_s$ is illustrated, and it is found out that they are in acceptable range, as suggested by Planck. In addition, the acquired values for amplitude of scalar perturbation reveals the ability of the model for depicting a good picture of the universe in one of the earliest stage. As a further argument, the non-Gaussianity is investigated displaying that the model prediction stands in $68\%$ CL regime; according to latest Planck data.

    ↳ gr-qchep-phPRD(2016)·31 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.