Thu·Jul 20, 2017Thursday·July 20, 2017

1. 01*

   New Class of Two-Loop Neutrino Mass Models with Distinguishable Phenomenology

   Qing-Hong Cao🇨🇳 · Shao-Long Chen🇨🇳 · Ernest Ma🇺🇸 · Bin Yan🇨🇳 · Dong-Ming Zhang🇨🇳

   We discuss a new class of neutrino mass models generated in two loops, and explore specifically three new physics scenarios: (A) doubly charged scalar, (B) dark matter, and (C) leptoquark and diquark, which are verifiable at the 14 TeV LHC Run-II. We point out how the different Higgs insertions will distinguish our two-loop topology with others if the new particles in the loop are in the simplest representations of the SM gauge group.

   hep-phhep-exPLB(2018)·13 citations
2. 02*

   Scale Invariant Top Condensate

   Archil Kobakhidze🇦🇺 · Shelley Liang🇦🇺

   We propose a scale invariant model of dynamical electroweak symmetry breaking via top condensation within the minimal top condensate see-saw model. The classical scale invariance is realized nonlinearly by introducing conformal compensator scalar field, the dilaton, which plays crucial role in successful predictions for the Higgs boson. The dilaton mass and its mixing with the composite Higgs boson appears only at 2-loop level, both being proportional to the hierarchy between the electroweak and compositeness scales, $\propto v/\Lambda$. The mass scales in our model are generated via the mechanism of dimensional transmutation and the hierarchy $v/\Lambda \ll 1$ is radiatively stable, thus resolving the fine-tuning problem of the standard top condensate models.

   hep-ph3 citations
3. 03*

   Evidence of quasi-partonic higher-twist effects in deep inelastic scattering at HERA at moderate $Q^2$

   Leszek Motyka🇵🇱 · Mariusz Sadzikowski🇵🇱 · Wojciech Slominski🇵🇱 · Katarzyna Wichmann🇩🇪

   The combined HERA data for the inclusive deep inelastic scattering (DIS) cross sections for the momentum transfer $Q^2>1$ GeV${}^2$ are fitted within the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) framework at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) accuracy, complemented by a QCD-inspired parameterisation of twist 4 corrections. A modified form of the input parton density functions is also included, motivated by parton saturation mechanism at small Bjorken $x$ and at a low scale. These modifications lead to a significant improvement of the data description in the region of low $Q^2$. For the whole data sample, the new benchmark NNLO DGLAP fit yields ${\chi }^2$ / d.o.f. $\simeq 1.2$ to be compared to 1.5 resulting from the standard NNLO DGLAP fit. We discuss the results in the context of the parton saturation picture and describe the impact of the higher-twist corrections on the derived parton density functions. The resulting description of the longitudinal proton structure function $F_L$ is consistent with the HERA data. Our estimates of higher-twist contributions to the proton structure functions are comparable to the leading-twist contributions at low $Q^2\simeq 2$ GeV${}^2$ and $x\simeq 10^{-5}$. The $x$-dependence of the twist 4 corrections obtained from the best fit is consistent with the leading twist 4 quasi-partonic operators, corresponding to an exchange of four interacting gluons in the $t$-channel.

   hep-phEPJC(2018)·15 citations
4. 04*

   Exploring CP-even scalars of a Two Higgs-doublet model in future $e^{-}p$ colliders

   Chuene Mosomane🇿🇦 · Mukesh Kumar🇿🇦 · Alan S. Cornell🇿🇦 · Bruce Mellado🇿🇦

   In this proceeding we shall explore the potential of a future $e^{-}p$ collider to probe the CP-even scalars in a two Higgs doublet model. We consider Type-I in this study. The mass of the lighter scalar particle is considered to be the Higgs-boson, $m_h=125$ GeV, and a heavy scalar $m_H=270$ GeV. The centre of mass energy for the $e^{-}p$ collision is considered as in the Large Hadron Electron Collider and the Future Circular Hadron Electron Collider configurations, by fixing the proton beam energy to be $E_p=7$ and 50 TeV, respectively, and an electron beam energy of $E_e=60$ GeV. Production cross sections of these scalars are also shown at higher electron beam energies. Future prospects of these studies are also discussed.

   hep-phJ.Phys.Conf.Ser.(2017)·11 citations
5. 05*

   Effective potential in ultraviolet completions for composite Higgs models

   Maarten Golterman🇺🇸 · Yigal Shamir🇮🇱

   We consider a class of composite Higgs models based on asymptotically free $SO(d)$ gauge theories with $d$ odd, with fermions in two irreducible representations, and in which the Higgs field arises as a pseudo Nambu-Goldstone boson and the top quark is partially composite. The Nambu-Goldstone coset containing the Higgs field, or Higgs coset, is either $SU(4)/Sp(4)$ or $SU(5)/SO(5)$, whereas the top partners live in two-index representations of the relevant flavor group ($SU(4)$ or $SU(5)$). In both cases, there is a large number of terms in the most general four-fermion lagrangian describing the interaction of third-generation quarks with the top partners. We derive the top-induced effective potential for the Higgs coset together with the singlet pseudo Nambu-Goldstone boson associated with the non-anomalous axial symmetry, to leading order in the couplings between the third-generation quarks and the composite sector. We obtain expressions for the low-energy constants in terms of top-partner two-point functions. We revisit the effective potential of another composite Higgs model that we have studied previously, which is based on an $SU(4)$ gauge theory and provides a different realization of the $SU(5)/SO(5)$ coset. The top partners of this model live in the fundamental representation of $SU(5)$, and, as a result, the effective potential of this model is qualitatively different from the $SO(d)$ gauge theories. We also discuss the role of the isospin-triplet fields contained in the $SU(5)/SO(5)$ coset, and show that, without further constraints on the four-fermion couplings, an expectation value for the the Higgs field will trigger the subsequent condensation of an isospin-triplet field.

   hep-phhep-latPRD(2018)·49 citations
6. 06*

   Constraining the scalar singlet and inert dark matter models using neutron stars

   Grigoris Panotopoulos🇵🇹 · Ilidio Lopes🇵🇹

   In the present work we study the scalar singlet as well as the Two-Higgs Doublet model inert dark matter particles impact on compact objects, and we provide the first constraints of the parameter space using neutron stars. The models discussed here are characterized by two free parameters, namely the mass $M_{\chi }$ of the scalar particle that plays the role of the dark matter in the Universe, and a dimensionless coupling constant ${\lambda }_{\chi }$ that determines the strength of the interaction of the dark matter particles with the Standard Model Higgs boson. By considering a typical neutron star we were able to obtain constraints on scalar dark matter depending on the DM annihilation cross section and self-interaction coupling constant. Our findings show that i) for heavy DM particles neutron stars can provide us with bounds better that the current limits from direct detection searches only when the self-annihilations of DM particles are negligible and the DM self-interaction coupling constant is very small, while ii) for light DM particles the bounds obtained here are comparable to limits from Higgs invisible decays unless the DM particles are extremely light.

   hep-phastro-ph.HEPRD(2017)·1 citation
7. 07*

   Neutrino mass in flavor dependent gauged lepton model

   Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

   We study a neutrino model introducing an additional nontrivial gauged lepton symmetry where the neutrino masses are induced at two-loop level while the first and second charged-leptons of the standard model are done at one-loop level. As a result of model structure, we can predict one massless active neutrino, and there is a dark matter candidate. Then we discuss neutrino mass matrix, muon anomalous magnetic moment, lepton flavor violations, oblique parameters, and relic density of dark matter taking into account the experimental constraints.

   hep-phPRD(2018)·5 citations
8. 08*

   Decays of light mesons triggered by chiral chemical potential

   A.A. Andrianov🇷🇺 · V.A. Andrianov🇷🇺 · D. Espriu🇪🇸 · A.E. Putilova🇷🇺 · A.V. Iakubovich🇷🇺

   Light meson ( $\pi ,\sigma ,a_0$) properties in the environment with chiral imbalance are analyzed with the help of meson effective Lagrangian associated with QCD. New spatial parity violating decays of scalar mesons arise as a result of mixing of $\pi$ and $a_0$ mesons under influence of chiral charge density. The pion electromagnetic form-factor gets an unusual parity-odd contribution. Pion effective masses depend on their velocities and may vanish in flight. The possible determination of chiral chemical potential in heavy ion collisions based on above mentioned phenomena is discussed.

   hep-phhep-exnucl-thActa Phys.Polon.Supp.(2017)·7 citations
9. 09*

   A simple parameterization of two-photon exchange amplitude

   Dmitry Borisyuk🇺🇦 · Alexander Kobushkin🇺🇦

   We present a simple parameterization of the two-photon exchange amplitude in elastic electron-proton scattering, suitable for fast numerical evaluation.

   hep-ph4 citations
10. 10*

    Constraining the EW Hierarchy from the Weak Gravity Conjecture

    Luis E. Ibanez🇪🇸 · Victor Martin-Lozano🇩🇪 · Irene Valenzuela🇩🇪

    In this addendum we complement the remarks made in ref[1] constraining the value of the cosmological constant ${\Lambda }_4$ in terms of neutrino masses. Those were based on a sharpened version of the Weak Gravity Conjecture as applied to compactifications of the SM to lower dimensions. We argue that the same line of reasoning implies that for fixed values of ${\Lambda }_4$ and the Yukawa coupling of the lightest neutrino $Y_{{\nu }_1}$, the EW scale is bounded above. This is a trivial consequence of neutrino masses depending on the Higgs vev. In the case of massive Majorana neutrinos with a see-saw mechanism associated to a large scale $M\simeq 10^{10-14}$ GeV and $Y_{{\nu }_1}\simeq 10^{-3}$, one obtains that the EW scale cannot exceed $M_{EW}\lesssim 10^2-10^4$ GeV. From this point of view, the delicate fine-tuning required to get a small EW scale would be a mirage, since parameters yielding higher EW scales would be in the swampland and would not count as possible consistent theories. This would bring a new perspective into the issue of the EW hierarchy.

    ↳ hep-thhep-ph50 citations
11. 11*

    An Alternative Approach for Constraining the Galactic Magnetic Field and the Interstellar Radiation Field

    Maryam Tavakoli🇮🇷

    High energy cosmic ray electrons and positrons, during propagation in the Galaxy, mainly lose energy through either the inverse Compton scattering (ICS) off of the interstellar radiation field (ISRF) or emitting synchrotron radiation in the Galactic magnetic field (GMF). Emitted photons by these two main energy loss mechanisms contribute to, respectively, diffuse Galactic gamma rays and radio waves. The variation of the distribution of the ISRF and the GMF has a sizable impact on the spectrum of cosmic ray electrons and positrons throughout the Galaxy. This impact is revealed both locally through measuring the local flux of cosmic ray electrons and positrons and globally by observing the spectra and morphology of diffuse gamma rays and radio waves. In this paper, we quantify this impact and conclude that recent data from AMS-02, \textit{Fermi} and H.E.S.S experiments are powerful enough to be alternatively applied for constraining properties of the ISRF and the GMF.

    ↳ astro-ph.HEhep-ph0 citations
12. 12*

    Inflationary magneto-(non)genesis, increasing kinetic couplings, and the strong coupling problem

    Hossein Bazrafshan Moghaddam🇨🇦 · Evan McDonough🇨🇦 · Ryo Namba🇨🇦 · Robert H. Brandenberger🇨🇦

    We study the generation of magnetic fields during inflation making use of a coupling of the inflaton and moduli fields to electromagnetism via the photon kinetic term, and assuming that the coupling is an increasing function of time. We demonstrate that the strong coupling problem of inflationary magnetogenesis can be avoided by incorporating the destabilization of moduli fields after inflation. The magnetic field always dominates over the electric one, and thus the severe constraints on the latter from backreaction, which are the demanding obstacles in the case of a decreasing coupling function, do not apply to the current scenario. However, we show that this loophole to the strong coupling problem comes at a price: the normalization of the amplitude of magnetic fields is determined by this coupling term and is therefore suppressed by a large factor after the moduli destabilization completes. From this we conclude that there is no self-consistent and generic realization of primordial magnetogenesis producing scale-invariant fields in the case of an increasing kinetic coupling.

    ↳ astro-ph.COgr-qchep-phhep-thClass.Quant.Grav.(2018)·25 citations
13. 13*

    Transmuted Gravity Wave Signals from Primordial Black Holes

    Volodymyr Takhistov🇺🇸

    Primordial black holes (PBHs) interacting with compact stars in binaries lead to a new class of gravity wave signatures that we explore. A small $10^{-16}-10^{-7}{M}_{\odot }$ PBH captured by a neutron star or a white dwarf will eventually consume the host. The resulting black hole will have a mass of only $\sim 0.5-2.5M_{\odot }$, not expected from astrophysics. For a double neutron star binary system this leads to a transmutation into a black hole-neutron star binary, with a gravity wave signal detectable by the LIGO-VIRGO network. For a neutron star-white dwarf system this leads to a black hole-white dwarf binary, with a gravity wave signal detectable by LISA. Other systems, such as cataclysmic variable binaries, can also undergo transmutations. We describe gravity wave signals of the transmuted systems, stressing the differences and similarities with the original binaries. New correlating astrophysical phenomena, such as a double kilonova, can further help to distinguish these events. This setup evades constraints on solar mass PBHs and still allows for PBHs to constitute all of the dark matter. A lack of signal in future searches could constrain PBH parameter space.

    ↳ astro-ph.COastro-ph.HEhep-phPLB(2018)·65 citations
14. 14*

    Matter-Antimatter Coexistence Method for Finite Density QCD

    Hideo Suganuma (Kyoto U.)🇯🇵

    We propose a "matter-antimatter coexistence method" for finite-density lattice QCD, aiming at a possible solution of the sign problem. In this method, we consider matter and anti-matter systems on two parallel ${\mathbf{R}}^4$-sheets in five-dimensional Euclidean space-time. For the matter system $M$ with a chemical potential $\mu \in \mathbf{C}$ on a ${\mathbf{R}}^4$-sheet, we also prepare the anti-matter system $\bar{M}$ with $-{\mu }^{\ast }$ on the other ${\mathbf{R}}^4$-sheet shifted in the fifth direction. In the lattice QCD formalism, we introduce a correlation term between the gauge variables $U_{\nu }\equiv e^{iag{A}_{\nu }}$ in $M$ and ${\tilde{U}}_{\nu }\equiv e^{iag{\tilde{A}}_{\nu }}$ in $\bar{M}$, such as $S_{\lambda }\equiv {\sum }_{x,\nu }2\lambda \{N_c-\mathrm{Re}\mathrm{tr}[U_{\nu }(x){\tilde{U}}_{\nu }^{†}(x)]\}\simeq {\sum }_x\frac{1}{2}\lambda a^2\{A_{\nu }^a(x)-{\tilde{A}}_{\nu }^a(x){\}}^2$ with a real parameter $\lambda$. In the limit of $\lambda \to \infty$, a strong constraint ${\tilde{U}}_{\nu }(x)=U_{\nu }(x)$ is realized, and the total fermionic determinant is real and non-negative. In the limit of $\lambda \to 0$, this system goes to two separated ordinary QCD systems with the chemical potential of $\mu$ and $-{\mu }^{\ast }$. On a finite-volume lattice, if one takes an enough large value of $\lambda$, ${\tilde{U}}_{\nu }(x)\simeq U_{\nu }(x)$ is realized and there occurs a phase cancellation approximately between two fermionic determinants in $M$ and $\bar{M}$, which is expected to suppress the sign problem and to make the lattice calculation possible. For the obtained gauge configurations of the coexistence system, matter-side quantities are evaluated through their measurement only for the matter part $M$. By the calculations with gradually decreasing $\lambda$ and their extrapolation to $\lambda =0$, physical quantities in finite density QCD are expected to be estimated.

    ↳ hep-lathep-phhep-thActa Phys.Polon.Supp.(2017)·0 citations
15. 15*

    The KLASH Proposal

    David Alesini🇮🇹 · Danilo Babusci🇮🇹 · Daniele Di Gioacchino🇮🇹 · Claudio Gatti🇮🇹 · Gianluca Lamanna🇮🇹 · Carlo Ligi🇮🇹

    We propose a search of galactic axions with mass about 0.2 microeV using a large volume resonant cavity, about 50 m^3, cooled down to 4 K and immersed in a moderate axial magnetic field of about 0.6 T generated inside the superconducting magnet of the KLOE experiment located at the National Laboratory of Frascati of INFN. This experiment, called KLASH (KLoe magnet for Axion SearcH) in the following, has a potential sensitivity on the axion-to-photon coupling, g_agg, of about 6x10^-17 GeV-1, reaching the region predicted by KSVZ and DFSZ models of QCD axions.

    ↳ physics.ins-dethep-exhep-ph107 citations
16. 16*

    Bounding the speed of gravity with gravitational wave observations

    Neil Cornish🇺🇸 · Diego Blas🇨🇭 · Germano Nardini🇨🇭

    The time delay between gravitational wave signals arriving at widely separated detectors can be used to place upper and lower bounds on the speed of gravitational wave propagation. Using a Bayesian approach that combines the first three gravitational wave detections reported by the LIGO collaboration we constrain the gravitational waves propagation speed c_gw to the 90% credible interval 0.55 c < c_gw < 1.42 c, where c is the speed of light in vacuum. These bounds will improve as more detections are made and as more detectors join the worldwide network. Of order twenty detections by the two LIGO detectors will constrain the speed of gravity to within 20% of the speed of light, while just five detections by the LIGO-Virgo-Kagra network will constrain the speed of gravity to within 1% of the speed of light.

    ↳ gr-qchep-phhep-thPRL(2017)·92 citations
17. 17*

    Selected Topics in Cosmic Ray Physics

    R. Aloisio🇮🇹 · P. Blasi🇮🇹 · I. De Mitri🇮🇹 · S. Petrera🇮🇹

    The search for the origin of cosmic rays is as active as ever, mainly driven by new insights provided by recent pieces of observation. Much effort is being channelled in putting the so called supernova paradigm for the origin of galactic cosmic rays on firmer grounds, while at the highest energies we are trying to understand the observed cosmic ray spectra and mass composition and relating them to potential sources of extragalactic cosmic rays. Interestingly, a topic that has acquired a dignity of its own is the investigation of the transition region between the galactic and extragalactic components, once associated with the ankle and now increasingly thought to be taking place at somewhat lower energies. Here we summarize recent developments in the observation and understanding of galactic and extragalactic cosmic rays and we discuss the implications of such findings for the modelling of the transition between the two.

    ↳ astro-ph.HEhep-ph29 citations
18. 18*

    Search for solar Kaluza-Klein axion by annual modulation with the XMASS-I detector

    XMASS Collaboration: N. Oka🇯🇵 · K. Abe🇯🇵 · K. Hiraide🇯🇵 · K. Ichimura🇯🇵 · Y. Kishimoto🇯🇵 · K. Kobayashi🇯🇵 · M. Kobayashi🇯🇵 · S. Moriyama🇯🇵 · M. Nakahata🇯🇵 · T. Norita🇯🇵 · H. Ogawa🇯🇵 · K. Sato🇯🇵 and 29 other authors

    In theories with the large extra dimensions beyond the standard 4-dimensional spacetime, axions could propagate in such extra dimensions, and acquire Kaluza-Klein (KK) excitations. These KK axions are produced in the Sun and could solve unexplained heating of the solar corona. While most of the solar KK axions escape from the solar system, a small fraction is gravitationally trapped in orbits around the Sun. They would decay into two photons inside a terrestrial detector. The event rate is expected to modulate annually depending on the distance from the Sun. We have searched for the annual modulation signature using $832\times 359$ kg$\cdot$days of XMASS-I data. No significant event rate modulation is found, and hence we set the first experimental constraint on the KK axion-photon coupling of $4.8\times 10^{-12}{\mathrm{GeV}}^{-1}$ at 90% confidence level for a KK axion number density of ${\bar{n}}_{\mathrm{a}}=4.07\times 10^{13}{\mathrm{m}}^{-3}$, the total number of extra dimensions $n=2$, and the number of extra dimensions $\delta =2$ that axions can propagate in.

    ↳ hep-exastro-ph.COhep-phnucl-ex+1PTEP(2017)·18 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.