Thu·Feb 8, 2018Thursday·February 8, 2018

1. 01*

   Signals of the electroweak phase transition at colliders and gravitational wave observatories

   Mikael Chala🇬🇧 · Claudius Krause🇪🇸 · Germano Nardini🇨🇭

   If the electroweak phase transition (EWPT) is of strongly first order due to higher dimensional operators, the scale of new physics generating them is at the TeV scale or below. In this case the effective-field theory (EFT) neglecting operators of dimension higher than six may overlook terms that are relevant for the EWPT analysis. In this article we study the EWPT in the EFT to dimension eight. We estimate the reach of the future gravitational wave observatory LISA for probing the region in which the EWPT is strongly first order and compare it with the capabilities of the Higgs measurements via double-Higgs production at current and future colliders. We also match different UV models to the previously mentioned dimension-eight EFT and demonstrate that, from the top-down point of view, the double-Higgs production is not the best signal to explore these scenarios.

   hep-phJHEP(2018)·151 citations
2. 02*

   Model-independent determinations of the electron EDM and the role of diamagnetic atoms

   Timo Fleig🇫🇷 · Martin Jung🇩🇪

   We perform model-independent analyses extracting limits for the electric dipole moment of the electron and the P,T-odd scalar-pseudoscalar (S-PS) nucleon-electron coupling from the most recent measurements with atoms and molecules. The analysis using paramagnetic systems, only, is improved substantially by the inclusion of the recent measurement on HfF+ ions, but complicated by the fact that the corresponding constraints are largely aligned, owing to a general relation between the coefficients for the two contributions. Since this same relation does not hold in diamagnetic systems, it is possible to find atoms that provide essentially orthogonal constraints to those from para\-magnetic ones. However, the coefficients are suppressed in closed-shell systems and enhancements of P,T-odd effects are only prevalent in the presence of hyperfine interactions. We formulate the hyperfine-induced time-reversal-symmetry breaking S-PS nucleon-electron interaction in general atoms in a mixed perturbative and variational approach, based on electronic Dirac-wavefunctions including the effects of electron correlations. The method is applied to the Hg atom, yielding the first direct calculation of the coefficient of the S-PS nucleon-electron coupling in a diamagnetic system. This results in additionally improved model-independent limits for both the electron EDM and the nucleon-electron coupling from the global fit. Finally we employ this fit to provide indirect limits for several paramagnetic systems under investigation.

   hep-phphysics.atom-phJHEP(2018)·47 citations
3. 03*

   Dirac neutrino mixings from hidden $\mu -\tau$ symmetry

   Edgar R. Luna Terrazas🇲🇽 · Abdel Pérez-Lorenzana🇲🇽

   We explore masses and mixings for Dirac neutrinos in models where lepton number is conserved, under the guidance of a hidden, but broken, $\mu -\tau$ exchange symmetry, that makes itself evident in the squared hermitian mass matrix. We study the parameter space in the most general theory as allowed by current neutrino oscillation experiment data. By using a general parameterization of the mass matrix which contains only observable parameters we stablish that the amount of breaking of the symmetry is in the range of the atmospheric mass scale, without regard to the neutrino hierarchy, the absolute neutrino mass and the Dirac CP phase. An estimate of the invisible branching ratio for a Higgs boson decaying into Dirac neutrinos, $H\to \nu \overline{\nu }$ , is given and compared to recent measurements in this context.

   hep-phPLB(2018)·2 citations
4. 04*

   Same-sign WW scattering at the LHC: can we discover BSM effects before discovering new states?

   Jan Kalinowski🇵🇱 · Paweł Kozów🇵🇱 · Stefan Pokorski🇵🇱 · Janusz Rosiek🇵🇱 · Michał Szleper🇵🇱 · Sławomir Tkaczyk🇺🇸

   It is possible that measurements of vector boson scattering (VBS) at the LHC will reveal disagreement with Standard Model predictions, but no new particles will be observed directly. The task is then to learn as much as possible about the new physics from a VBS analysis carried within the framework of the Effective Field Theory (EFT). In this paper we discuss issues related to the correct usage of the EFT when the WW invariant mass is not directly accessible experimentally, as in purely leptonic W decay channels. The strategies for future data analyses in case such scenario indeed occurs are proposed.

   hep-phEPJC(2018)·52 citations
5. 05*

   High scale boundary conditions with an additional complex singlet

   John McDowall🇬🇧 · David J. Miller🇬🇧

   We investigate Planck scale boundary conditions on Higgs quartic interactions and their $\beta$-functions in the SM augmented by an additional complex scalar. We use renormalisation group running at two-loops, and include both theoretical and experimental constraints. We find that the boundary condition $\lambda ={\beta }_{\lambda }=0$ at the Planck scale is compatible with the current Higgs and top mass measurements, but requires additional scalars lighter than about $600$GeV.

   hep-phPRD(2018)·10 citations
6. 06*

   Constraining Gluonic Quartic Gauge Coupling Operators with $gg\to \gamma \gamma$

   John Ellis🇬🇧 · Shao-Feng Ge🇯🇵

   Gluon-gluon to photon-photon scattering $gg\to \gamma \gamma$ offers to the LHC experiments a uniquely powerful probe of dimension-8 operators in the Standard Model Effective Field Theory (SMEFT) that are quadratic in both the electromagnetic and gluonic field-strength tensors, such as would appear in the Born-Infeld extension of the Standard Model (SM). We use 13-TeV ATLAS data on the production of isolated photon pairs to set lower limits on the scales of dimension-8 operators $M\gtrsim 1$~TeV, and discuss the prospective sensitivities of possible future hadron colliders.

   hep-phhep-exPRL(2018)·47 citations
7. 07*

   Parton distributions and $\cos 2{\varphi }_h$ asymmetry induced by anomalous photon-quark coupling

   Xu Cao🇨🇳

   In the spectator models of the nucleon with scalar and axial-vector diquarks, we show that the effect of Pauli coupling in photon-quark vertex to the parton distribution functions (PDFs) of nucleon and azimuthal asymmetry in the unpolarized semi-inclusive deep inelastic scattering (SIDIS). This anomalous coupling gives obvious contribution to unpolarized and polarized PDFs, and also leads to a $\cos 2{\varphi }_h$ azimuthal asymmetry proportional to the squared Pauli form factor, due to the helicity flip of the struck quark. After determining the model parameters by fitting PDFs to the global fits, this new distribution for $\cos 2{\varphi }_h$ asymmetry is given numerically. In the framework of transverse momentum dependence (TMD), we find that it is positive and of a few percent in the kinematical regime of HERMES and COMPASS collaborations, in the same order of magnitude with Cahn effect.

   hep-phPRD(2018)·1 citation
8. 08*

   Algorithmic transformation of multi-loop Feynman integrals to a canonical basis

   Christoph Meyer🇩🇪

   The evaluation of multi-loop Feynman integrals is one of the main challenges in the computation of precise theoretical predictions for the cross sections measured at the LHC. In recent years, the method of differential equations has proven to be a powerful tool for the computation of Feynman integrals. It has been observed that the differential equation of Feynman integrals can in many instances be transformed into a so-called canonical form, which significantly simplifies its integration in terms of iterated integrals. The main result of this thesis is an algorithm to compute rational transformations of differential equations of Feynman integrals into a canonical form. Apart from requiring the existence of such a rational transformation, the algorithm needs no further assumptions about the differential equation. In particular, it is applicable to problems depending on multiple kinematic variables and also allows for a rational dependence on the dimensional regulator. First, the transformation law is expanded in the dimensional regulator to derive differential equations for the coefficients of the transformation. Using an ansatz in terms of rational functions, these differential equations are then solved to determine the transformation. This thesis also presents an implementation of the algorithm in the Mathematica package CANONICA, which is the first publicly available program to compute transformations to a canonical form for differential equations depending on multiple variables. The main functionality and its usage are illustrated with some simple examples. Furthermore, the package is applied to state-of-the-art integral topologies appearing in recent multi-loop calculations. These topologies depend on up to three variables and include previously unknown topologies contributing to higher-order corrections to the cross section of single top-quark production at the LHC.

   hep-ph4 citations
9. 09*

   Transverse Single Spin Asymmetry in $J/\psi$ Production

   Bipin Sonawane🇮🇳 · Anuradha Misra🇮🇳 · Siddhesh Padval🇮🇳 · Vaibhav Rawoot🇮🇳

   We estimate transverse single spin asymmetry (TSSA) in electroproduction of $J/\psi$ for J-Lab and EIC energies. We present estimates of TSSAs in $J/\psi$ production within generalized parton model (GPM) using recent parametrizations of gluon Sivers function (GSF) and compare the results obtained using color singlet model (CSM) with those obtained using color evaporation model (CEM) of quarkonium production.

   hep-phFew Body Syst.(2018)·2 citations
10. 10*

    Second-order QCD effects in Higgs boson production through vector boson fusion

    J. Cruz-Martinez🇬🇧 · T. Gehrmann🇨🇭 · E.W.N. Glover🇬🇧 · A. Huss🇨🇭

    We compute the factorising second-order QCD corrections to the electroweak production of a Higgs boson through vector boson fusion. Our calculation is fully differential in the kinematics of the Higgs boson and of the final state jets, and uses the antenna subtraction method to handle infrared singular configurations in the different parton-level contributions. Our results allow us to reassess the impact of the next-to-leading order (NLO) QCD corrections to electroweak Higgs-plus-three-jet production and of the next-to-next-to-leading order (NNLO) QCD corrections to electroweak Higgs-plus-two-jet production. The NNLO corrections are found to be limited in magnitude to around $\pm 5\%$ and are uniform in several of the kinematical variables, displaying a kinematical dependence only in the transverse momenta and rapidity separation of the two tagging jets.

    hep-phPLB(2018)·90 citations
11. 11*

    Virtual photon polarization and dilepton anisotropy in relativistic nucleus-nucleus collisions

    Enrico Speranza🇩🇪 · Amaresh Jaiswal🇮🇳 · Bengt Friman🇩🇪

    The polarization of virtual photons produced in relativistic nucleus-nucleus collisions provides information on the conditions in the emitting medium. In a hydrodynamic framework, the resulting angular anisotropy of the dilepton final state depends on the flow as well as on the transverse momentum and invariant mass of the photon. We illustrate these effects in dilepton production from quark-antiquark annihilation in the QGP phase and ${\pi }^{+}{\pi }^{-}$ annihilation in the hadronic phase for a static medium in global equilibrium and for a longitudinally expanding system.

    hep-phPLB(2018)·29 citations
12. 12*

    $T$-odd correlations in polarized top quark decays in the sequential decay $t(\uparrow )\to X_b+W^{+}(\to {\ell }^{+}+{\nu }_{\ell })$ and in the quasi three-body decay $t(\uparrow )\to X_b+{\ell }^{+}+{\nu }_{\ell }$

    M. Fischer🇩🇪 · S. Groote🇪🇪 · J.G. Körner🇩🇪

    We identify the $T$-odd structure functions that appear in the description of polarized top quark decays in the sequential decay $t(\uparrow )\to X_b+W^{+}(\to {\ell }^{+}+{\nu }_{\ell })$ (two structure functions) and the quasi-three-body decay $t(\uparrow )\to X_b+{\ell }^{+}+{\nu }_{\ell }$ (one structure function). A convenient measure of the magnitude of the $T$-odd structure functions is the contribution of the imaginary part Im $g_R$ of the right-chiral tensor coupling $g_R$ to the $T$-odd structure functions which we work out. Contrary to the case of QCD the NLO electroweak corrections to polarized top quark decays admit of absorptive one-loop vertex contributions. We analytically calculate the imaginary parts of the relevant four electroweak one-loop triangle vertex diagrams and determine their contributions to the $T$-odd helicity structure functions that appear in the description of polarized top quark decays.

    hep-phhep-exPRD(2018)·10 citations
13. 13*

    Viscous effects on the dynamical evolution of QCD matter during the first-order confinement phase transition in heavy-ion collisions

    Bohao Feng🇨🇳 · Carsten Greiner🇩🇪 · Shuzhe Shi🇺🇸 · Zhe Xu🇨🇳

    We investigate viscous effects on the dynamical evolution of QCD matter during the first-order phase transition, which may happen in heavy-ion collisions. We first obtain the first-order phase transition line in the QCD phase diagram under the Gibbs condition by using the MIT bag model and the hadron resonance gas model for the equation of state of partons and hadrons. The viscous pressure, which corresponds to the friction in the energy balance, is then derived from the energy and net baryon number conservation during the phase transition. We find that the viscous pressure relates to the thermodynamic change of the two-phase state and thus affects the timescale of the phase transition. Numerical results are presented for demonstrations.

    hep-phnucl-thPLB(2018)·10 citations
14. 14*

    Supernova Neutrino Neutrino Astronomy

    Vedran Brdar🇩🇪 · Manfred Lindner🇩🇪 · Xun-Jie Xu (MPIK Heidelberg)🇩🇪

    Modern neutrino facilities will be able to detect a large number of neutrinos from the next Galactic supernova. We investigate the viability of the triangulation method to locate a core-collapse supernova by employing the neutrino arrival time differences at various detectors. We perform detailed numerical fits in order to determine the uncertainties of these time differences for the cases when the core collapses into a neutron star or a black hole. We provide a global picture by combining all the relevant current and future neutrino detectors. Our findings indicate that in the scenario of a neutron star formation, supernova can be located with precision of 1.5 and 3.5 degrees in declination and right ascension, respectively. For the black hole scenario, sub-degree precision can be reached.

    hep-phastro-ph.HEhep-exJCAP(2018)·45 citations
15. 15*

    Model Selection Using Cosmic Chronometers with Gaussian Processes

    Fulvio Melia🇺🇸 · Manoj K. Yennapureddy🇺🇸

    The use of Gaussian Processes with a measurement of the cosmic expansion rate based solely on the observation of cosmic chronometers provides a completely cosmology-independent reconstruction of the Hubble constant H(z) suitable for testing different models. The corresponding dispersion sigma_H is smaller than ~9% over the entire redshift range (0 < z < 2) of the observations, rivaling many kinds of cosmological measurements available today. We use the reconstructed H(z) function to test six different cosmologies, and show that it favours the R_h=ct universe, which has only one free parameter (i.e., H_0) over other models, including Planck LCDM. The parameters of the standard model may be re-optimized to improve the fits to the reconstructed H(z) function, but the results have smaller p-values than one finds with R_h=ct.

    ↳ astro-ph.COastro-ph.GAgr-qchep-phJCAP(2018)·50 citations
16. 16*

    Unitarity and Universality in non relativistic Conformal Field theory

    Sridip Pal🇺🇸

    We relate the notion of unitarity of a $SL(2,\mathbf{R})$ invariant field theory with that of a Schrodinger field theory using the fact that $SL(2,\mathbf{R})$ is a subgroup of Schrodinger group. Exploiting $SL(2,\mathbf{R})$ unitarity, we derive the unitarity bounds and null conditions for a Schrödinger field theory (for the neutral as well as the charged sector). In non integer dimensions the theory is shown to be non-unitary. Furthermore, the use of $SL(2,\mathbf{R})$ subgroup opens up the possibility of borrowing results from 1D $SL(2,\mathbf{R})$ invariant field theory to explore Schrodinger field theory, in particular, the sector with zero charge. We explore the consequences of $SL(2,\mathbf{R})$ symmetry e.g. the convergence of operator product expansion in the kinematic limit, where all the operators (neutral and/or charged) are on same temporal slice ($x=constant$), the universal behavior of weighted spectral density function, existence of infinite number of $SL(2,\mathbf{R})$ primaries, the analytic behavior of three point function as a function of spatial separation. We discuss the implication of imposing parity invariance ($\tau \to -\tau$) in addition to Schrodinger invariance and emphasize its difference from time reversal ($\tau \to -\tau$ with charge conjugation).

    ↳ hep-thcond-mat.quant-gascond-mat.str-elhep-phPRD(2018)·21 citations
17. 17*

    Predictions for isobaric collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 200 GeV from a multiphase transport model

    Wei-Tian Deng🇨🇳 · Xu-Guang Huang🇨🇳 · Guo-Liang Ma🇨🇳 · Gang Wang🇺🇸

    The isobaric collisions of ${}_{44}^{96}$Ru + ${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr + ${}_{40}^{96}$Zr have recently been proposed to discern the charge separation signal of the chiral magnetic effect (CME). In this article, we employ the string melting version of a multiphase transport model to predict various charged-particle observables, including $dN/d\eta$, $p_T$ spectra, elliptic flow ($v_2$), and particularly possible CME signals in Ru + Ru and Zr + Zr collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 200 GeV. Two sets of the nuclear structure parametrization have been explored, and the difference between the two isobaric collisions appears to be small, in terms of $dN/d\eta$, $p_T$ spectra, and $v_2$ for charged particles. We mimic the CME by introducing an initial charge separation that is proportional to the magnetic field produced in the collision, and study how the final-state interactions affect the CME observables. The relative difference in the CME signal between the two isobaric collisions is found to be robust, insensitive to the final-state interactions.

    ↳ nucl-thhep-phnucl-exPRC(2018)·40 citations
18. 18*

    Perturbative matching of continuum and lattice quasi-distributions

    Tomomi Ishikawa🇨🇳

    Matching of the quasi parton distribution functions between continuum and lattice is addressed using lattice perturbation theory specifically with Wilson-type fermions. The matching is done for nonlocal quark bilinear operators with a straight Wilson line in a spatial direction. We also investigate operator mixing in the renormalization and possible O(a) operators for the nonlocal operators based on a symmetry argument on lattice.

    ↳ hep-lathep-phnucl-thEPJ Web Conf.(2018)·2 citations
19. 19*

    Subleading Regge limit from a soft anomalous dimension

    Robin Brüser🇩🇪 · Simon Caron-Huot🇨🇦 · Johannes M. Henn🇩🇪

    Wilson lines capture important features of scattering amplitudes, for example soft effects relevant for infrared divergences, and the Regge limit. Beyond the leading power approximation, corrections to the eikonal picture have to be taken into account. In this paper, we study such corrections in a model of massive scattering amplitudes in N = 4 super Yang-Mills, in the planar limit, where the mass is generated through a Higgs mechanism. Using known three-loop analytic expressions for the scattering amplitude, we find that the first power suppressed term has a very simple form, equal to a single power law. We propose that its exponent is governed by the anomalous dimension of a Wilson loop with a scalar inserted at the cusp, and we provide perturbative evidence for this proposal. We also analyze other limits of the amplitude and conjecture an exact formula for a total cross-section at high energies.

    ↳ hep-thhep-phJHEP(2018)·47 citations
20. 20*

    $F_4$ , $E_6$ and $G_2$ Exceptional Gauge Groups in Vacuum Domain Structure Model

    Amir Shahlaei🇮🇷 · Shahnoosh Rafibakhsh🇮🇷

    Using vacuum domain structure model, trivial static potentials in various representations of $F_4$, $E_6$ and $G_2$ exceptional groups are calculated by means of the unit center element. Due to the absence of the non-trivial center elements, the potential of every representation is screened at far distances. However, the linear part is observed at intermediate quark separations which is investigated by the decomposition of the exceptional group to its maximal subgroups. Comparing the group factor of the super-group with the corresponding one obtained from the non-trivial center elements of $SU(3)$ subgroup, shows that $SU(3)$ is not the direct cause of temporary confinement in any of the exceptional groups. However, the trivial potential obtained from the group decomposition to the $SU(3)$ subgroup is the same as the potential of the super-group itself. In addition, any regular or singular decomposition to the $SU(2)$ subgroup which produces the Cartan generator with the same elements as $h_1$, in any exceptional group, leads to the linear intermediate potential of the exceptional gauge groups. The other $SU(2)$ decompositions with the Cartan generator different from $h_1$, are still able to describe the linear potential if the number of $SU(2)$ non-trivial center element which emerge in the decompositions is the same. As a result, it is the center vortices quantized in terms of non-trivial center element of the $SU(2)$ subgroup which give rise to the intermediate confinement in the static potentials.

    ↳ hep-thhep-phPRD(2018)·5 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.