Mon·Jul 31, 2017Monday·July 31, 2017

1. 01*

   Vacuum Stability and Perturbativity of SU(3) Scalars

   Matti Heikinheimo🇫🇮 · Kristjan Kannike🇪🇪 · Florian Lyonnet🇺🇸 · Martti Raidal🇪🇪 · Kimmo Tuominen🇫🇮 · Hardi Veermäe🇪🇪

   We calculate the vacuum stability conditions and renormalisation group equations for the extensions of standard model with a higher colour multiplet scalar up to the representation $15^{\prime }$ that leaves the strong interaction asymptotically free. In order to find the vacuum stability conditions, we calculate the orbit spaces for the self-couplings of the higher multiplets, which for the representations $15$ and $15^{\prime }$ of $SU(3{)}_c$ are highly complicated. However, if the scalar potential is linear in orbit space variables, it is sufficient to know the convex hull of the orbit space. In contrast to the self-couplings of other multiplets, we find that the scalar quartic couplings of the representations $3$ and $8$ walk rather than run, remaining nearly constant and perturbative over a vast energy range. We describe the conditions for walking couplings using a schematic model. With these technical results at hand we revise earlier results of generation of new scales with large $SU(3{)}_c$ scalar multiplets. Our results are easily extendable to models of new physics with additional $SU(3)$ or SU($N$) gauge symmetries.

   hep-phhep-thJHEP(2017)·15 citations
2. 02*

   The Inflaton Portal to Dark Matter

   Lucien Heurtier🇧🇪

   We consider the possibility that the inflaton is part of the dark sector and interacts with the standard model through a portal interaction with a heavy complex scalar field in equilibrium with the standard model at high energies. The inflaton and dark matter are encapsulated in a single complex field and both scalar sectors are charged under different (approximate) global U(1)'s such that the dark matter, as well as the visible pseudo-scalar are taken to be relatively light, as pseudo Nambu-Goldstone bosons of the theory. The dark matter relic density is populated by Freeze-In productions through the inflaton portal. In particular, after the reheating, production of dark matter by inflaton decay is naturally suppressed thanks to Planck stringent constraints on the dark quartic coupling, therefore preserving the non thermal scenario from any initial condition tuning.

   hep-phastro-ph.COJHEP(2017)·19 citations
3. 03*

   On the coverage of the pMSSM by simplified model results

   Federico Ambrogi🇦🇹 · Sabine Kraml🇫🇷 · Suchita Kulkarni🇦🇹 · Ursula Laa🇫🇷 · Andre Lessa🇧🇷 · Wolfgang Waltenberger🇦🇹

   We investigate to which extent the SUSY search results published by ATLAS and CMS in the context of simplified models actually cover the more realistic scenarios of a full model. Concretely, we work within the phenomenological MSSM (pMSSM) with 19 free parameters and compare the constraints obtained from SModelSv1.1.1 with those from the ATLAS pMSSM study in arXiv:1508.06608. We find that about 40-45% of the points excluded by ATLAS escape the currently available simplified model constraints. For these points we identify the most relevant topologies which are not tested by the current simplified model results. In particular, we find that topologies with asymmetric branches, including 3-jet signatures from gluino-squark associated production, could be important for improving the current constraining power of simplified models results. Furthermore, for a better coverage of light stops and sbottoms, constraints for decays via heavier neutralinos and charginos, which subsequently decay visibly to the lightest neutralino are also needed.

   hep-phhep-exEPJC(2018)·31 citations
4. 04*

   Minimal Non-Abelian Supersymmetric Twin Higgs

   Marcin Badziak🇵🇱 · Keisuke Harigaya🇺🇸

   We propose a minimal supersymmetric Twin Higgs model that can accommodate tuning of the electroweak scale for heavy stops better than 10% with high mediation scales of supersymmetry breaking. A crucial ingredient of this model is a new SU(2)_X gauge symmetry which provides a D-term potential that generates a large SU(4) invariant coupling for the Higgs sector and only small set of particles charged under SU(2)_X, which allows the model to be perturbative around the Planck scale. The new gauge interaction drives the top yukawa coupling small at higher energy scales, which also reduces the tuning.

   hep-phJHEP(2017)·36 citations
5. 05*

   Exotic Trajectories Effects on Neutrino Oscillations

   Jonathan Miller🇨🇱 · Roman Pasechnik🇸🇪

   Recently, for the first time, exotic loop trajectories were observed in a photon triple slit experiment. We discuss possible origins and potential impacts of analogical exotic trajectories in neutrino production, propagation and detection onto the neutrino oscillation observables.

   hep-phhep-thquant-ph0 citations
6. 06*

   Reduction of Feynman integrals to integrals of Schläfli functions

   S. Srednyak🇺🇸

   We show that off-shell perturbative amplitudes with arbitrary number of external lines and complex masses can be reduced to $I$-fold integrals of the generalized Schläfli functions, where $I$ is the number of lines in the corresponding vacuum diagram which is independent of the number of external lines. The Schläfli functions are obtained as analytic continuation of the volume of the spherical simplex as a function of the hyperplane parameters that define the simplex. These functions have nice and thoroughly studied analytic, geometric and number theoretic properties. They possess Gauss-Manin connection and in conformal case are expressed by iterated integrals. Our representation sheds new light on geometry of particle configuration spaces in perturbation theory.

   hep-ph0 citations
7. 07*

   Surface Magnetic Catalysis

   Hao-Lei Chen🇨🇳 · Kenji Fukushima🇯🇵 · Xu-Guang Huang🇨🇳 · Kazuya Mameda🇯🇵

   We study fermions in a magnetic field in a finite size cylinder. With the boundary condition for the fermion flux, we show that the energy spectra and the wave-functions are modified by the finite size effect; the boundary makes the degenerate Landau levels appear only partially for states with small angular momenta, while the boundary effect becomes stronger for states with large angular momenta. We find that mode accumulation at the boundary occurs for large angular momenta and the magnetic effect is enhanced on the boundary surface. Using a simple fermionic model, we quantify the magnetic catalysis, i.e. the magnetic enhancement of the fermion pair condensation, in a finite size cylinder. We confirm that the magnetic catalysis is strongly amplified at the boundary due to the mode accumulation.

   hep-phcond-mat.mes-hallhep-thnucl-thPRD(2017)·33 citations
8. 08*

   The nucleon as a test case to calculate vector-isovector form factors at low energies

   Stefan Leupold (UU)🇸🇪

   Extending a recent suggestion for hyperon form factors to the nucleon case, dispersion theory is used to relate the low-energy vector-isovector form factors of the nucleon to the pion vector form factor. The additionally required input, i.e. the pion-nucleon scattering amplitudes are determined from relativistic next-to-leading-order (NLO) baryon chiral perturbation theory including the nucleons and optionally the Delta baryons. Two methods how to include pion rescattering are compared: (a) solving the Muskhelishvili-Omnes (MO) equation and (b) using an N/D approach. It turns out that the results differ strongly from each other. Furthermore the results are compared to a fully dispersive calculation of the (subthreshold) pion-nucleon amplitudes based on Roy-Steiner (RS) equations. In full agreement with the findings from the hyperon sector it turns out that the inclusion of Delta baryons is not an option but a necessity to obtain reasonable results. The magnetic isovector form factor depends strongly on a low-energy constant of the NLO Lagrangian. If it is adjusted such that the corresponding magnetic radius is reproduced, then the results for the corresponding pion-nucleon scattering amplitude (based on the MO equation) agree very well with the RS results. Also in the electric sector the Delta degrees of freedom are needed to obtain the correct order of magnitude for the isovector charge and the corresponding electric radius. Yet quantitative agreement is not achieved. If the subtraction constant that appears in the solution of the MO equation is not taken from nucleon+Delta chiral perturbation theory but adjusted such that the electric radius is reproduced, then one obtains also in this sector a pion-nucleon scattering amplitude that agrees well with the RS results.

   hep-phnucl-thEPJA(2018)·84 citations
9. 09*

   Self-heating dark matter via semi-annihilation

   Ayuki Kamada🇰🇷 · Hee Jung Kim🇰🇷 · Hyungjin Kim🇰🇷 · Toyokazu Sekiguchi🇰🇷

   The freeze-out of dark matter (DM) depends on the evolution of the DM temperature. The DM temperature does not have to follow the standard model one, when the elastic scattering is not sufficient to maintain the kinetic equilibrium. We study the temperature evolution of the semi-annihilating DM, where a pair of the DM particles annihilate into one DM particle and another particle coupled to the standard model sector. We find that the kinetic equilibrium is maintained solely via semi-annihilation until the last stage of the freeze-out. After the freeze-out, semi-annihilation converts the mass deficit to the kinetic energy of DM, which leads to non-trivial evolution of the DM temperature. We argue that the DM temperature redshifts like radiation as long as the DM self-interaction is efficient. We dub this novel temperature evolution as self-heating. Notably, the structure formation is suppressed at subgalactic scales like keV-scale warm DM but with GeV-scale self-heating DM if the self-heating lasts roughly until the matter-radiation equality. The long duration of the self-heating requires the large self-scattering cross section, which in turn flattens the DM density profile in inner halos. Consequently, self-heating DM can be a unified solution to apparent failures of cold DM to reproduce the observed subgalactic scale structure of the Universe.

   hep-phastro-ph.COPRL(2018)·40 citations
10. 10*

    $CP$ asymmetries in charm decays into neutral kaons

    Di Wang🇨🇳 · Fu-Sheng Yu🇨🇳 · Hsiang-nan Li🇹🇼

    We find a new $CP$-violation effect in charm decays into neutral kaons, which results from the interference between two tree (Cabibbo-favored and doubly Cabibbo-suppressed) amplitudes with the mixing of final-state mesons. This effect, estimated to be of an order of $10^{-3}$, is much larger than the direct $CP$ asymmetries in these decays, but missed in the literature. It can be revealed by measuring the difference of the time-dependent $CP$ asymmetries in the $D^{+}\to {\pi }^{+}{K}_S^0$ and $D_s^{+}\to K^{+}{K}_S^0$ modes, which are accessible at the LHCb and Belle II experiments. If confirmed, the new effect has to be taken into account, as the above direct $CP$ asymmetries are used to search for new physics.

    hep-phhep-exPRL(2017)·51 citations
11. 11*

    State-of-the-Art Calculation of the Decay Rate of Electroweak Vacuum in Standard Model

    So Chigusa🇯🇵 · Takeo Moroi🇯🇵 · Yutaro Shoji🇯🇵

    The decay rate of the electroweak (EW) vacuum is calculated in the framework of the standard model (SM) of particle physics, using the recent progresses in the understanding of the decay rate of metastable vacuum in gauge theories. We give a manifestly gauge-invariant expression of the decay rate. We also perform a detailed numerical calculation of the decay rate. With the best-fit values of the SM parameters, we find that the decay rate of the EW vacuum per unit volume is about $10^{-577}\mathrm{Gy}{\mathrm{r}}^{-1}\mathrm{Gp}{\mathrm{c}}^{-3}$; with the uncertainty in the top mass, the decay rate is estimated as $10^{-295}-10^{-1465}\mathrm{Gy}{\mathrm{r}}^{-1}\mathrm{Gp}{\mathrm{c}}^{-3}$.

    hep-phPRL(2017)·95 citations
12. 12*

    Covariant spectator theory of quark-antiquark bound states: Mass spectra and vertex functions of heavy and heavy-light mesons

    Sofia Leitão🇵🇹 · Alfred Stadler🇵🇹 · M. T. Peña🇵🇹 · Elmar P. Biernat🇵🇹

    We use the covariant spectator theory with an effective quark-antiquark interaction, containing Lorentz scalar, pseudoscalar, and vector contributions, to calculate the masses and vertex functions of, simultaneously, heavy and heavy-light mesons. We perform least-square fits of the model parameters, including the quark masses, to the meson spectrum and systematically study the sensitivity of the parameters with respect to different sets of fitted data. We investigate the influence of the vector confining interaction by using a continuous parameter controlling its weight. We find that vector contributions to the confining interaction between 0% and about 30% lead to essentially the same agreement with the data. Similarly, the light quark masses are not very tightly constrained. In all cases, the meson mass spectra calculated with our fitted models agree very well with the experimental data. We also calculate the mesons wave functions in a partial wave representation and show how they are related to the meson vertex functions in covariant form.

    hep-phnucl-thPRD(2017)·30 citations
13. 13*

    Gluon condensate from the Polyakov loop

    J. P. Carlomagno🇦🇷 · J. C. Rojas🇨🇱

    We estimate the temperature dependence of the gluon condensate from the Polyakov loop effective potential. It is presented how this analytic approach provides a simple picture for the electric gluon condensate around the deconfinement temperature, showing that it drops to zero in a temperature range which is in good agreement with different pure gauge lattice results.

    hep-phEPJ Web Conf.(2018)·0 citations
14. 14*

    Mass Dependence of Higgs Production at Large Transverse Momentum through a Bottom Quark Loop

    Eric Braaten🇺🇸 · Hong Zhang🇺🇸 · Jia-Wei Zhang🇨🇳

    In the production of the Higgs through a bottom-quark loop, the transverse momentum distribution of the Higgs at large $P_T$ is complicated by its dependence on two other important scales: the bottom quark mass $m_b$ and the Higgs mass $m_H$. A strategy for simplifying the calculation of the cross section at large $P_T$ is to calculate only the leading terms in its expansion in $m_b^2/P_T^2$. In this paper, we consider the bottom-quark-loop contribution to the parton process $q\bar{q}\to H+g$ at leading order in ${\alpha }_s$. We show that the leading power of $1/P_T^2$ can be expressed in the form of a factorization formula that separates the large scale $P_T$ from the scale of the masses. All the dependence on $m_b$ and $m_H$ can be factorized into a distribution amplitude for $b\bar{b}$ in the Higgs, a distribution amplitude for $b\bar{b}$ in a real gluon, and an endpoint contribution. The factorization formula can be used to organize the calculation of the leading terms in the expansion in $m_b^2/P_T^2$ so that every calculation involves at most two scales.

    hep-phPRD(2018)·4 citations
15. 15*

    Cosmic-ray transport in the heliosphere with HelioProp

    Andrea Vittino🇩🇪 · Carmelo Evoli🇮🇹 · Daniele Gaggero🇳🇱

    Before being detected at Earth, charged cosmic rays propagate across the Solar System and undergo interactions with the turbulent solar wind and with the heliospheric magnetic field. As a result, they are subject to a series of processes that include diffusion, convection, energy losses and drifts, which significantly affect the shape and the intensity of the cosmic-ray fluxes at low energies. Here we illustrate how all these mechanisms can be realistically modelled with HelioProp, our public tool designed to treat cosmic-ray transport through the heliosphere in a charge-dependent way. We present a detailed description of the features of the code and we illustrate in a quantitative way the effects that the propagation in the heliosphere can have on the different cosmic-ray species with a particular emphasis on the antiparticle channels relevant for dark matter indirect detection.

    ↳ astro-ph.HEhep-phphysics.space-phPoS(2018)·18 citations
16. 16*

    Proton and neutron electromagnetic form factors and uncertainties

    Zhihong Ye🇺🇸 · John Arrington🇺🇸 · Richard J. Hill🇺🇸 · Gabriel Lee🇮🇱

    We determine the nucleon electromagnetic form factors and their uncertainties from world electron scattering data. The analysis incorporates two-photon exchange corrections, constraints on the low-Q2 and high-Q2 behavior, and additional uncertainties to account for tensions between different data sets and uncertainties in radiative corrections.

    ↳ nucl-exhep-phnucl-thPLB(2018)·187 citations
17. 17*

    Thermodynamic constraints on a varying cosmological-constant-like term from the holographic equipartition law with a power-law corrected entropy

    Nobuyoshi Komatsu🇯🇵

    A power-law corrected entropy based on a quantum entanglement is considered to be a viable black-hole entropy. In this study, as an alternative to Bekenstein-Hawking entropy, a power-law corrected entropy is applied to Padmanabhan's holographic equipartition law to thermodynamically examine an extra driving term in the cosmological equations for a flat Friedmann-Robertson-Walker universe at late times. Deviations from the Bekenstein-Hawking entropy generate an extra driving term (proportional to the $\alpha$-th power of the Hubble parameter, where $\alpha$ is a dimensionless constant for the power-law correction) in the acceleration equation, which can be derived from the holographic equipartition law. Interestingly, the value of the extra driving term in the present model is constrained by the second law of thermodynamics. From the thermodynamic constraint, the order of the driving term is found to be consistent with the order of the cosmological constant measured by observations. In addition, the driving term tends to be constant-like when $\alpha$ is small, i.e., when the deviation from the Bekenstein-Hawking entropy is small.

    ↳ gr-qcastro-ph.COhep-phPRD(2017)·27 citations
18. 18*

    Multicomponent van der Waals equation of state: Applications in nuclear and hadronic physics

    Volodymyr Vovchenko🇩🇪 · Anton Motornenko🇩🇪 · Paolo Alba🇩🇪 · Mark I. Gorenstein🇺🇦 · Leonid M. Satarov🇩🇪 · Horst Stoecker🇩🇪

    A generalization of the quantum van der Waals equation of state for a multi-component system in the grand canonical ensemble is proposed. The model includes quantum statistical effects and allows to specify the parameters characterizing repulsive and attractive forces for each pair of particle species. The model can be straightforwardly applied to the description of asymmetric nuclear matter and also for mixtures of interacting nucleons and nuclei. Applications of the model to the equation of state of an interacting hadron resonance gas are discussed.

    ↳ nucl-thcond-mat.stat-mechhep-phPRC(2017)·72 citations
19. 19*

    Exact RG Flow Equations and Quantum Gravity

    S.P. de Alwis🇺🇸

    We discuss the different forms of the functional RG equation and their relation to each other. In particular we suggest a generalized background field version that is close in spirit to the Polchinski equation as an alternative to the Wetterich equation to study Weinberg's asymptotic safety program for defining quantum gravity, and argue that the former is better suited for this purpose. Using the heat kernel expansion and proper time regularization we find evidence in support of this program in agreement with previous work.

    ↳ hep-thgr-qchep-phJHEP(2018)·42 citations
20. 20*

    A dark matter model that reconciles tensions between the cosmic-ray $e^{\pm }$ excess and the gamma-ray and CMB constraints

    Qian-Fei Xiang🇨🇳 · Xiao-Jun Bi🇨🇳 · Su-Jie Lin🇨🇳 · Peng-Fei Yin🇨🇳

    The cosmic-ray (CR) $e^{\pm }$ excess observed by AMS-02 can be explained by dark matter (DM) annihilation. However, the DM explanation requires a large annihilation cross section which is strongly disfavored by other observations, such as the Fermi-LAT gamma-ray observation of dwarf galaxies and the Planck observation of the cosmic microwave background (CMB). Moreover, the DM annihilation cross section required by the CR $e^{\pm }$ excess is also too large to generate the correct DM relic density with thermal production. In this work we use the Breit-Wigner mechanism with a velocity dependent DM annihilation cross section to reconcile these tensions. If DM particles accounting for the CR $e^{\pm }$ excess with $v\sim \mathcal{O}(10^{-3})$ are very close to a resonance in the physical pole case, their annihilation cross section in the Galaxy reaches a maximal value. On the other hand, the annihilation cross section would be suppressed for DM particles with smaller relative velocities in dwarf galaxies and at recombination, which may affect the gamma-ray and CMB observations, respectively. We find a proper parameter region that can simultaneously explain the AMS-02 results and the thermal relic density, while satisfying the Fermi-LAT and Planck constraints.

    ↳ astro-ph.HEhep-phPLB(2017)·20 citations
21. 21*

    About the rapidity and helicity distributions of the W bosons produced at LHC

    Elisabetta Manca🇮🇹 · Olmo Cerri🇮🇹 · Nicolo Foppiani🇮🇹 · Gigi Rolandi🇮🇹

    $W$ bosons are produced at LHC from a forward-backward symmetric initial state. Their decay to a charged lepton and a neutrino has a strong spin analysing power. The combination of these effects results in characteristic distributions of the pseudorapidity of the leptons decaying from $W^{+}$ and $W^{-}$ of different helicity. This observation may open the possibility to measure precisely the $W^{+}$ and $W^{-}$ rapidity distributions for the two transverse polarisation states of $W$ bosons produced at small transverse momentum.

    ↳ hep-exhep-phJHEP(2017)·12 citations
22. 22*

    Neutrino mass and dark energy constraints from redshift-space distortions

    Amol Upadhye🇺🇸

    Cosmology in the near future promises a measurement of the sum of neutrino masses, a fundamental Standard Model parameter, as well as substantially-improved constraints on the dark energy. We use the shape of the BOSS redshift-space galaxy power spectrum, in combination with CMB and supernova data, to constrain the neutrino masses and the dark energy. Essential to this calculation are several recent advances in non-linear cosmological perturbation theory, including FFT methods, redshift space distortions, and scale-dependent growth. Our 95% confidence upper bound of 180 meV on the sum of masses degrades substantially to 540 meV when the dark energy equation of state and its first derivative are also allowed to vary, representing a significant challenge to current constraints. We also study the impact of additional galaxy bias parameters, finding that a greater allowed range of scale-dependent bias only slightly shifts the preferred neutrino mass value, weakens its upper bound by about 20%, and has a negligible effect on the other cosmological parameters.

    ↳ astro-ph.COhep-phJCAP(2019)·54 citations
23. 23*

    Limiting neutrino magnetic moments with Borexino Phase-II solar neutrino data

    M. Agostini🇮🇹 · K. Altenmüller🇩🇪 · S. Appel🇩🇪 · V. Atroshchenko🇷🇺 · Z. Bagdasarian🇩🇪 · D. Basilico🇮🇹 · G. Bellini🇮🇹 · J. Benziger🇺🇸 · D. Bick🇩🇪 · G. Bonfini🇮🇹 · D. Bravo🇺🇸 · B. Caccianiga🇮🇹 and 95 other authors

    A search for the solar neutrino effective magnetic moment has been performed using data from 1291.5 days exposure during the second phase of the Borexino experiment. No significant deviations from the expected shape of the electron recoil spectrum from solar neutrinos have been found, and a new upper limit on the effective neutrino magnetic moment of ${\mu }_{\nu }^{eff}$ $<$ 2.8$\cdot$10${}^{-11}$ ${\mu }_B$ at 90\% c.l. has been set using constraints on the sum of the solar neutrino fluxes implied by the radiochemical gallium experiments.Using the limit for the effective neutrino moment, new limits for the magnetic moments of the neutrino flavor states, and for the elements of the neutrino magnetic moments matrix for Dirac and Majorana neutrinos, are derived.

    ↳ hep-exhep-phPRD(2017)·266 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.