Wed·Oct 5, 2016Wednesday·October 5, 2016

1. 01*

   Double parton scattering in pair-production of $J/\psi$ mesons at the LHC revisited

   Christoph Borschensky🇩🇪 · Anna Kulesza🇩🇪

   Double parton scattering (DPS) is studied at the example of $J/\psi$ pair-production in the LHCb and ATLAS experiments of the Large Hadron Collider (LHC) at centre-of-mass energies of $\sqrt{S}=$ 7, 8, and 13 TeV. We report theoretical predictions delivered to the LHCb and ATLAS collaborations adjusted for the fiducial volumes of the corresponding measurements during Run I and provide new predictions at 13 TeV collision energy. It is shown that DPS can lead to noticeable contributions in the distributions of longitudinal variables of the di-$J/\psi$ system, especially at 13 TeV. The increased DPS rate in double $J/\psi$ production at high energies will open up more possibilities for the separation of single parton scattering (SPS) and DPS contributions in future studies.

   hep-phPRD(2017)·46 citations
2. 02*

   Constraints on Relaxion Windows

   Kiwoon Choi🇰🇷 · Sang Hui Im🇩🇪

   We examine the low energy phenomenology of the relaxion solution to the weak scale hierarchy problem. Assuming that the Hubble friction is responsible for a dissipation of the relaxion energy, we identify the cosmological relaxion window which corresponds to the parameter region compatible with a given value of the acceptable number of inflationary $e$-foldings. We then discuss a variety of observational constraints on the relaxion window, including those from astrophysical and cosmological considerations. We find that majority of the parameter space with a relaxion mass $m_{\varphi }\gtrsim 100$ eV or a relaxion decay constant $f\lesssim 10^7$ GeV is excluded by existing constraints. There is an interesting parameter region with $m_{\varphi }\sim 0.2-10$ GeV and $f\sim \mathrm{few}-200$ TeV, which is allowed by existing constraints, but can be probed soon by future beam dump experiments such as the SHiP experiment, or by improved EDM experiments.

   hep-phastro-ph.COJHEP(2016)·75 citations
3. 03*

   Covariant diagrams for one-loop matching

   Zhengkang Zhang (U Michigan & DESY)🇺🇸

   We present a diagrammatic formulation of recently-revived covariant functional approaches to one-loop matching from an ultraviolet (UV) theory to a low-energy effective field theory. Various terms following from a covariant derivative expansion (CDE) are represented by diagrams which, unlike conventional Feynman diagrams, involve gauge-covariant quantities and are thus dubbed "covariant diagrams." The use of covariant diagrams helps organize and simplify one-loop matching calculations, which we illustrate with examples. Of particular interest is the derivation of UV model-independent universal results, which reduce matching calculations of specific UV models to applications of master formulas. We show how such derivation can be done in a more concise manner than the previous literature, and discuss how additional structures that are not directly captured by existing universal results, including mixed heavy-light loops, open covariant derivatives, and mixed statistics, can be easily accounted for.

   hep-phhep-thJHEP(2017)·113 citations
4. 04*

   Probing the diffractive production of gauge bosons at forward rapidities

   E. Basso🇧🇷 · V. P. Goncalves🇧🇷 · M. S. Rangel🇧🇷

   The gauge boson production at forward rapidities in single diffractive events at the LHC is investigated considering $pp$ collisions at $\sqrt{s}=$ 8 and 13 TeV. The impact of gap survival effects is analysed using two different models for the soft rescattering contributions. We demonstrate that using the Forward Shower Counter Project at LHCb -- HERSCHEL, together with the Vertex Locator -- VELO, it is possible to discriminate diffractive production of the gauge bosons $W$ and $Z$ from the non-diffractive processes and studies of the Pomeron structure and diffraction phenomenology are feasible. Moreover, we show that the analysis of this process can be useful to constrain the modelling of the gap survival effects.

   hep-phhep-exEPJC(2016)·5 citations
5. 05*

   Rare semileptonic $B\to K(\pi )l_i^{-}{l}_j^{+}$ decay in vector leptoquark model

   Murugeswaran Duraisamy🇺🇸 · Suchismita Sahoo🇮🇳 · Rukmani Mohanta🇮🇳

   We investigate the consequence of vector leptoquarks on the rare semileptonic lepton flavour violating decays of $B$ meson which are more promising and effective channels to probe the new physics signal. We constrain the resulting new leptoquark parameter space by using the branching ratios of $B_{s,d}\to l^{+}{l}^{-}$, $K_L\to l^{+}{l}^{-}$ and ${\tau }^{-}\to l^{-}\gamma$ processes. We estimate the branching ratios of rare lepton flavour violating $B\to K(\pi )l_i^{-}{l}_j^{+}$ processes using the constrained leptoquark couplings. We also compute the forward-backward asymmetries and the lepton non-universality parameters of the LFV decays in the vector leptoquark model. Furthermore, we study the effect of vector leptoquark on $(g-2{)}_{\mu }$ anomaly.

   hep-phPRD(2017)·42 citations
6. 06*

   The Liouville equation for flavour evolution of neutrinos and neutrino wave packets

   Rasmus Sloth Lundkvist Hansen🇩🇪 · Alexei Yu. Smirnov🇩🇪

   We consider several aspects related to the form, derivation and applications of the Liouville equation (LE) for flavour evolution of neutrinos. To take into account the quantum nature of neutrinos we derive the evolution equation for the matrix of densities using wave packets instead of Wigner functions. The obtained equation differs from the standard LE by an additional term which is proportional to the difference of group velocities. We show that this term describes loss of the propagation coherence in the system. In absence of inelastic collisions, the LE can be reduced to a single derivative equation over a trajectory coordinate. Additional time and spacial dependence may steam from initial (production) conditions. The transition from single neutrino evolution to the evolution of a neutrino gas is considered.

   hep-phastro-ph.SRJCAP(2016)·15 citations
7. 07*

   Semileptonic decays of ${\Lambda }_c$ baryons in the relativistic quark model

   R. N. Faustov🇷🇺 · V. O. Galkin🇷🇺

   Motivated by recent experimental progress in studying weak decays of the ${\Lambda }_c$ baryon we investigate its semileptonic decays in the framework of the relativistic quark model based on the quasipotential approach with the QCD-motivated potential. The form factors of the ${\Lambda }_c\to \Lambda l{\nu }_l$ and ${\Lambda }_c\to nl{\nu }_l$ decays are calculated in the whole accessible kinematical region without extrapolations and additional model assumptions. Relativistic effects are systematically taken into account including transformations of baryon wave functions from the rest to moving reference frame and contributions of the intermediate negative-energy states. Baryon wave functions found in the previous mass spectrum calculations are used for the numerical evaluation. Comprehensive predictions for decay rates, asymmetries and polarization parameters are given. They agree well with available experimental data.

   hep-phhep-exEPJC(2016)·55 citations
8. 08*

   A study of the gamma* - f0(980) transition form factors

   P. Kroll🇩🇪

   The spin wave function of the f0(980)-meson is constructed under the assumption that the meson is dominantly a quark-antiquark state. This wave function is used in a calculation of the gamma* - f0 transition form factors. In the real-photon limit the results for the transverse form factor are compared to the large momentum transfer data measured by the BELLE collaboration recently. It turns out that, for the momentum-transfer range explored by BELLE, the collinear approximation does not suffer, power corrections to it, modeled as quark transverse moment effects, seem to be needed. Mixing of the f0 with the sigma(500) is also briefly discussed.

   hep-phEPJC(2017)·12 citations
9. 09*

   Vacuum alignment and radiatively induced Fermi scale

   Tommi Alanne🇩🇰

   We extend the discussion about vacuum misalignment by quantum corrections in models with composite pseudo-Goldstone Higgs boson to renormalisable models with elementary scalars. As a concrete example, we propose a framework, where the hierarchy between the unification and the Fermi scale emerges radiatively. This scenario provides an interesting link between the unification and Fermi scale physics.

   hep-phEPJ Web Conf.(2017)·0 citations
10. 10*

    Bottomonium-like states: physics case for energy scan above the $B\bar{B}$ threshold at Belle-II

    A.E. Bondar🇷🇺 · R.V. Mizuk🇷🇺 · M.B. Voloshin🇺🇸

    The Belle-II experiment is expected to collect large data samples at the ${\rm Y}(4S)$ and ${\rm Y}(5S)$ resonances to study primarily $B$ and $B_s$ mesons. We discuss what other data above the $B\bar{B}$ threshold are of interest. We propose to perform a high-statistics energy scan from the $B\bar{B}$ threshold up to the highest possible energy, and to collect data at the ${\rm Y}(6S)$ and at higher mass states if they are found in the scan. We emphasize the interest in increasing the maximal energy from 11.24\,GeV to 11.5 - 12\,GeV in the future. These data are needed for investigation of bottomonium and bottomonium-like states.

    hep-phhep-exMod.Phys.Lett.A(2017)·34 citations
11. 11*

    Searching for New Physics in Semi-Leptonic Baryon Decays

    Elvio Di Salvo🇫🇷 · Ziad J. Ajaltouni🇫🇷

    We propose two different and complementary observables for singling out possible signals of physics beyond the standard model in the semi-leptonic decays ${\Lambda }_b\to {\Lambda }_c\ell {\bar{\nu }}_{\ell }$, both with the $\tau$ lepton and with a light lepton. The two observables are the partial decay width and a T-odd asymmetry, whose respective sensitivities to scalar and/or pseudo-scalar coupling are calculated as functions of the parameters characterizing new physics. Two different form factors are used. Three particular cases are discussed and analyzed in detail.

    hep-phMod.Phys.Lett.A(2017)·8 citations
12. 12*

    The Slab Method to Measure the Topological Susceptibility

    Wolfgang Bietenholz🇲🇽 · Krzysztof Cichy🇩🇪 · Philippe de Forcrand🇨🇭 · Arthur Dromard🇩🇪 · Urs Gerber🇲🇽

    In simulations of a model with topological sectors, algorithms which proceed in small update steps tend to get stuck in one sector, especially on fine lattices. This distorts the numerical results; in particular it is not straightforward to measure the topological susceptibility chi_t. We test a method to measure chi_t even if configurations from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as "slab". This enables the evaluation of chi_t, as we demonstrate with numerical results for non-linear sigma-models and for 2-flavour QCD. In the latter case, the gradient flow is applied for the smoothing of the gauge configurations, and the slab method results for chi_t are stable over a broad range of flow times.

    ↳ hep-latcond-mat.stat-mechhep-phPoS(2016)·14 citations
13. 13*

    Renormalisation Group Flow and Kaon Condensation

    Boris Krippa🇬🇧

    Functional renormalisation group approach is applied to a system of kaons with finite chemical potential. A set of approximate flow equations for the effective couplings is derived and solved. At high scale the system is found to be at the normal phase whereas at some critical value of the running scale it undergoes the phase transition (PT) to the phase with a spontaneously broken symmetry with the kaon condensate as an order parameter. The value of the condensate turns out to be quite sensitive to the kaon-kaon scattering length.

    ↳ nucl-thhep-phJ.Phys.G(2017)·0 citations
14. 14*

    Single-Field Inflation and the Local Ansatz: Distinguishability and Consistency

    Roland de Putter🇺🇸 · Olivier Doré🇺🇸 · Daniel Green🇺🇸 · Joel Meyers🇨🇦

    The single-field consistency conditions and the local ansatz have played separate but important roles in characterizing the non-Gaussian signatures of single- and multifield inflation respectively. We explore the precise relationship between these two approaches and their predictions. We demonstrate that the predictions of the single-field consistency conditions can never be satisfied by a general local ansatz with deviations necessarily arising at order $(n_s-1{)}^2$. This implies that there is, in principle, a minimum difference between single- and (fully local) multifield inflation in observables sensitive to the squeezed limit such as scale-dependent halo bias. We also explore some potential observational implications of the consistency conditions and its relationship to the local ansatz. In particular, we propose a new scheme to test the consistency relations. In analogy with delensing of the cosmic microwave background, one can deproject the coupling of the long wavelength modes with the short wavelength modes and test for residual anomalous coupling.

    ↳ hep-thastro-ph.COhep-phPRD(2017)·12 citations
15. 15*

    Permanent Electric Dipole Moments of Single-, Two-, and Three-Nucleon Systems

    Andreas Wirzba🇩🇪 · Jan Bsaisou🇩🇪 · Andreas Nogga🇩🇪

    A nonzero electric dipole moment (EDM) of the neutron, proton, deuteron or helion, in fact, of any finite system necessarily involves the breaking of a symmetry, either by the presence of external fields (i.e. electric fields leading to the case of induced EDMs) or explicitly by the breaking of the discrete parity and time-reflection symmetries in the case of permanent EDMs. We discuss two theorems describing these phenomena and report about the cosmological motivation for an existence of CP breaking beyond what is generated by the Kobayashi-Maskawa mechanism in the Standard Model and what this might imply for the permanent electric dipole moments of the nucleon and light nuclei by estimating a window of opportunity for physics beyond what is currently known. Recent - and in the case of the deuteron even unpublished - results for the relevant matrix elements of nuclear EDM operators are presented and the relevance for disentangling underlying New Physics sources are discussed.

    ↳ nucl-thhep-lathep-phquant-phIJMPE(2017)·13 citations
16. 16*

    Leptonic decay-constant ratio $f_K/f_{\pi }$ from clover-improved $N_f=2+1$ QCD

    Enno E. Scholz🇩🇪 · Stephan Durr🇩🇪

    The leptonic decay-constant ratio $f_K/f_{\pi }$ is calculated from lattice-QCD simulations using $N_f=2+1$ dynamical fermion flavors in the clover-improved formulation and 2-HEX smearing. The simulations were performed for a range of mass-degenerate light quarks including the physical point and at various lattice couplings and volumes, allowing to quantify all relevant sources of systematic uncertainties for our final number of the decay-constant ratio. Utilizing input from chiral perturbation theory, we also quote the charged decay-constant ratio $f_{K^{\pm }}/f_{{\pi }^{\pm }}$. With further input from super-allowed nuclear $\beta$-decays, eventually we obtain an estimate for the CKM-matrix element $V_{\mathrm{us}}$.

    ↳ hep-lathep-phPoS(2016)·5 citations
17. 17*

    Modified Gravity Explains Dark Matter?

    Taishi Katsuragawa🇯🇵 · Shinya Matsuzaki🇯🇵

    We explore a new horizon of modified gravity from the viewpoint of the particle physics. As a concrete example, we take the $F(R)$ gravity to raise a question: can a scalar particle ("scalaron") derived from the $F(R)$ gravity be a dark matter candidate? We place the limit on the parameter in a class of $F(R)$ gravity model from the constraint on the scalaron as a dark matter. The role of the screening mechanism and compatibility with the dark energy problem are addressed.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2017)·74 citations
18. 18*

    Empirical parametrizations of the resonance amplitudes based on the Siegert's theorem

    G. Ramalho🇧🇷

    We present parametrizations of the ${\gamma }^{\ast }N\to N(1535)1/2^{-}$, ${\gamma }^{\ast }N\to N(1520)3/2^{-}$ and ${\gamma }^{\ast }N\to \Delta (1232)3/2^{+}$ transition amplitudes that are compatible with the analytic constraints at the pseudothreshold (Siegert's theorem). The presented parametrizations also provide a fair description of the experimental data. For the case of the ${\gamma }^{\ast }N\to \Delta (1232)3/2^{+}$ transition, we discuss how the pion cloud parametrizations of the electric and the Coulomb quadrupole form factors can be adjusted according to the Siegert's theorem.

    ↳ nucl-thhep-exhep-phnucl-exJPS Conf.Proc.(2017)·0 citations
19. 19*

    Critical fluctuations in models with van der Waals interactions

    V. Vovchenko🇩🇪 · D. V. Anchishkin🇺🇦 · M. I. Gorenstein🇺🇦 · R. V. Poberezhnyuk🇺🇦 · H. Stoecker🇩🇪

    Particle number fluctuations are considered within the van der Waals (VDW) equation, which contains both attractive (mean-field) and repulsive (eigenvolume) interactions. The VDW equation is used to calculate the scaled variance of particle number fluctuations in generic Boltzmann VDW system and in nuclear matter. The strongly intensive measures $\Delta [E^{\ast },N]$ and $\Sigma [E^{\ast },N]$ of the particle number and excitation energy fluctuations are also considered, and, similarly, show singular behavior near the critical point. The $\Delta [E^{\ast },N]$ measure is shown to attain both positive and negative values in the vicinity of critical point. Based on universality argument, similar behavior is expected to occur in the vicinity of the QCD critical point.

    ↳ nucl-thhep-phActa Phys.Polon.Supp.(2017)·4 citations
20. 20*

    The N/D method with non-perturbative left-hand-cut discontinuity and the ${}^1{S}_0$ $NN$ partial wave

    D.R. Entem🇪🇸 · J.A. Oller🇪🇸

    In this letter we deduce an integral equation that allows to calculate the exact left-hand-cut discontinuity for an uncoupled $S$-wave partial-wave amplitude in potential scattering for a given finite-range potential. The results obtained from the $N/D$ method for the partial-wave amplitude are rigorous, since now the discontinuities along the left-hand cut and right-hand cut are exactly known. This solves the open question with respect to the $N/D$ method and the effect on the final result of the non-perturbative iterative diagrams in the evaluation of $\Delta (A)$. A big advantage of the method is that short-range physics (corresponding to integrated out degrees of freedom within low-energy Effective Field Theory) does not contribute to $\Delta (A)$ and it manifests through the extra subtractions that are implemented within the method. We show the equivalence of the $N/D$ method and the Lippmann-Schwinger (LS) equation for a nonsingular ${}^1{S}_0$ $NN$ potential (Yukawa potential). The equivalence between the $N/D$ method with one extra subtraction and the LS equation renormalized with one counter term or with subtractive renormalization also holds for the singular attractive higher-order ChPT potentials. The $N/D$ method also allows to evaluate partial-wave amplitudes with a higher number of extra subtractions, that we fix in terms of shape parameters within the effective range expansion. The result at NNLO shows that the ${}^1{S}_0$ phase shifts might be accurately described once the electromagnetic and charge symmetry breaking terms are included. Our present results can be extended to higher partial waves as well as to coupled channel scattering.

    ↳ nucl-thhep-phPLB(2017)·25 citations
21. 21*

    Excited and exotic charmonium, $D_s$ and $D$ meson spectra for two light quark masses from lattice QCD

    Gavin K. C. Cheung🇬🇧 · Cian O'Hara🇮🇪 · Graham Moir🇬🇧 · Michael Peardon🇮🇪 · Sinéad M. Ryan🇮🇪 · Christopher E. Thomas🇬🇧 · David Tims🇮🇪

    We present highly-excited charmonium, $D_s$ and $D$ meson spectra from dynamical lattice QCD calculations with light quarks corresponding to $M_{\pi }\sim 240$ MeV and compare these to previous results with $M_{\pi }\sim 400$ MeV. Utilising the distillation framework, large bases of carefully constructed interpolating operators and a variational procedure, we extract and reliably identify the continuum spin of an extensive set of excited mesons. These include states with exotic quantum numbers which, along with a number with non-exotic quantum numbers, we identify as having excited gluonic degrees of freedom and interpret as hybrid mesons. Comparing the spectra at the two different $M_{\pi }$, we find only a mild light-quark mass dependence and no change in the overall pattern of states.

    ↳ hep-lathep-phJHEP(2016)·140 citations
22. 22*

    Towards a Unified Model of Neutrino-Nucleus Reactions for Neutrino Oscillation Experiments

    S.X. Nakamura (Osaka Univ.)🇯🇵 · H. Kamano (KEK, J-PARC)🇯🇵 · Y. Hayato (ICRR, Univ. of Tokyo)🇯🇵 · M. Hirai (Nippon Inst. Tech.)🇯🇵 · W. Horiuchi (Hokkaido Univ.)🇯🇵 · S. Kumano (KEK, J-PARC)🇯🇵 · T. Murata (Osaka Univ.)🇯🇵 · K. Saito (Tokyo Univ. of Sci.)🇯🇵 · M. Sakuda (Okayama Univ.)🇯🇵 · T. Sato (Osaka Univ., J-PARC)🇯🇵 · Y. Suzuki (Niigata Univ., RIKEN)🇯🇵

    A precise description of neutrino-nucleus reactions will play a key role in addressing fundamental questions such as the leptonic CP violation and the neutrino mass hierarchy through analyzing data from next-generation neutrino oscillation experiments. The neutrino energy relevant to the neutrino-nucleus reactions spans a broad range and, accordingly, the dominant reaction mechanism varies across the energy region from quasi-elastic scattering through nucleon resonance excitations to deep inelastic scattering. This corresponds to transitions of the effective degree of freedom for theoretical description from nucleons through meson-baryon to quarks. The main purpose of this review is to report our recent efforts towards a unified description of the neutrino-nucleus reactions over the wide energy range; recent overall progress in the field is also sketched. Starting with an overview of the current status of neutrino-nucleus scattering experiments, we formulate the cross section to be commonly used for the reactions over all the energy regions. A description of the neutrino-nucleon reactions follows and, in particular, a dynamical coupled-channels model for meson productions in and beyond the $\Delta$(1232) region is discussed in detail. We then discuss the neutrino-nucleus reactions, putting emphasis on our theoretical approaches. We start the discussion with electroweak processes in few-nucleon systems studied with the correlated Gaussian method. Then we describe quasi-elastic scattering with nuclear spectral functions, and meson productions with a $\Delta$-hole model. Nuclear modifications of the parton distribution functions determined through a global analysis are also discussed. Finally, we discuss issues to be addressed for future developments.

    ↳ nucl-thhep-exhep-phRept.Prog.Phys.(2017)·42 citations
23. 23*

    Dynamical role of Polyakov loops in the QCD thermodynamics

    N.O. Agasian🇷🇺 · M.S. Lukashov🇷🇺 · Yu.A. Simonov🇷🇺

    Polyakov loops $L_a(T),a=3,8,...$ are shown to give the most important nonperturbative contribution to the thermodynamic potentials. Derived from the gluonic field correlators they enter as factors into free energy. It is shown in the $SU(3)$ case that $L_a(T)$ define to a large extent the behavior of the free energy and the trace anomaly $I(T)$, most sensitive to nonperturbative effects.

    ↳ hep-lathep-phhep-thMod.Phys.Lett.A(2016)·15 citations
24. 24*

    $\bar{D}D$ meson pair production in antiproton-nucleus collisions

    R. Shyam🇮🇳 · K. Tsushima🇧🇷

    We study the $\bar{D}D$ (${\bar{D}}^0{D}^0$ and $D^{-}{D}^{+}$) charm meson pair production in antiproton ($\bar{p}$) induced reactions on nuclei at beam energies ranging from threshold to several GeV. Our model is based on an effective Lagrangian approach that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The reaction proceeds via the $t$-channel exchanges of ${\Lambda }_c^{+}$, ${\Sigma }_c^{+}$, and ${\Sigma }_c^{++}$ baryons in the initial collision of the antiproton with one of the protons of the target nucleus. The medium effects on the exchanged baryons are included by incorporating in the corresponding propagators, the effective charm baryon masses calculated within a quark-meson coupling (QMC) model. The wave functions of the bound proton have been determined within the QMC model as well as in a phenomenological model where they are obtained by solving the Dirac equation with appropriate scalar and vector potentials. The initial- and final-state distortion effects have been approximated by using an eikonal approximation-based procedure. Detailed numerical results are presented for total and double differential cross sections for the ${\bar{D}}^0{D}^0$ and $D^{-}{D}^{+}$ production reactions on ${}^{16}$O and ${}^{90}$Zr targets. It is noticed that at $\bar{p}$ beam momenta of interest to the $\bar{P}ANDA$ experiment, medium effects lead to noticeable enhancements in the charm meson production cross sections.

    ↳ nucl-thhep-exhep-phnucl-exPRD(2016)·12 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.