Thu·Apr 12, 2018Thursday·April 12, 2018

1. 01*

   Long-lived Heavy Neutrinos from Higgs Decays

   Frank F. Deppisch🇬🇧 · Wei Liu🇬🇧 · Manimala Mitra🇮🇳

   We investigate the pair-production of right-handed neutrinos via the Standard Model (SM) Higgs boson in a gauged $B-L$ model. The right-handed neutrinos with a mass of few tens of GeV generating viable light neutrino masses via the seesaw mechanism naturally exhibit displaced vertices and distinctive signatures at the LHC and proposed lepton colliders. The production rate of the right-handed neutrinos depends on the mixing between the SM Higgs and the exotic Higgs associated with the $B-L$ breaking, whereas their decay length depends on the active-sterile neutrino mixing. We focus on the displaced leptonic final states arising from such a process, and analyze the sensitivity reach of the LHC and proposed lepton colliders in probing the active-sterile neutrino mixing. We show that mixing to muons as small as $V_{\mu N}\approx 10^{-7}$ can be probed at the LHC with 100 fb${}^{-1}$ and at proposed lepton colliders with 5000 fb${}^{-1}$. The future high luminosity run at LHC and the proposed MATHUSLA detector may further improve this reach by an order of magnitude.

   hep-phhep-exJHEP(2018)·111 citations
2. 02*

   Phenomenology of the Generalised Scotogenic Model with Fermionic Dark Matter

   Claudia Hagedorn🇩🇰 · Juan Herrero-Garcia🇦🇺 · Emiliano Molinaro🇩🇰 · Michael A. Schmidt🇦🇺

   We study a simple extension of the Standard Model that accounts for neutrino masses and dark matter. The Standard Model is augmented by two Higgs doublets and one Dirac singlet fermion, all charged under a new dark global symmetry. It is a generalised version of the Scotogenic Model with Dirac fermion dark matter. Masses for two neutrinos are generated radiatively at one-loop level. We study the case where the singlet fermion constitutes the dark matter of the Universe. We study in depth the phenomenology of the model, in particular the complementarity between dark matter direct detection and charged lepton flavour violation observables. Due to the strong limits from the latter, dark matter annihilations are suppressed and the relic abundance is set by coannihilations with (and annihilations of) the new scalars if the latter and the Dirac fermion are sufficiently degenerate in mass. We discuss how different ratios of charged lepton flavour violating processes can be used to test the model. We also discuss the detection prospects of the charged scalars at colliders. In some cases these leave ionising tracks and in others have prompt decays, depending on the flavour in the final state and neutrino mass orderings.

   hep-phJHEP(2018)·65 citations
3. 03*

   It's all right(-handed neutrinos): a new $W^{\prime }$ model for the $R_{D^{(\ast )}}$ anomaly

   Pouya Asadi🇺🇸 · Matthew R. Buckley🇺🇸 · David Shih🇺🇸

   The measured $B$-meson semi-leptonic branching ratios $R_D$ and $R_{D^{\ast }}$ have long-standing deviations between theory and experiment. We introduce a model which explains both anomalies through a single interaction by introducing a right-handed neutrino as the missing energy particle. This interaction is mediated by a heavy charged vector boson ($W^{\prime }$) which couples only to right-handed quarks and leptons of the Standard Model through the mixing of these particles with new vector-like fermions. Previous $W^{\prime }$ models for the $R_{D^{(\ast )}}$ anomaly were strongly constrained from flavor changing neutral currents and direct collider searches for $Z^{\prime }\to \tau \tau$ resonances. We show that relying on right-handed fermion mixing enables us to avoid these constraints, as well as other severe bounds from electroweak precision tests and neutrino mixing.

   hep-phJHEP(2018)·104 citations
4. 04*

   Prospects for long-range reactor monitoring with gadolinium-loaded water-Cherenkov detectors

   Michael Leyton🇪🇸 · Stephen Dye🇺🇸

   Antineutrino detectors are practical, non-intrusive tools capable of remotely monitoring the activity of nuclear reactors. Here we explore the sensitivity of the Super-Kamiokande water-Cherenkov detector, following gadolinium loading, to antineutrinos from a nuclear reactor complex at a distance of approximately 190 km. The livetimes required to observe the two currently operating cores in the reactor complex depend on the activity of other reactors in the vicinity, as well as on estimates of detection efficiency and background rates. Under reasonable assumptions, we find that gadolinium-loaded Super-Kamiokande could detect the flux of antineutrinos from both cores at the Takahama reactor complex at 95% confidence level in 50 (10) live days 95% (50%) of the time, or the flux from one core in 397 (73) live days, provided that each core is operating at nominal power.

   ↳ physics.ins-dethep-exhep-ph1 citation
5. 05*

   Effective Approaches to QCD

   Hugo Reinhardt🇩🇪

   In this lecture I will explain the established pictures of the QCD vacuum and, in particular, the underlying confinement mechanism. These are: the magnetic monopole condensation (dual Meißner effect), the center vortex picture and the Gribov--Zwanziger picture. I will start by giving a survey of the common order and disorder parameters of confinement: the temporal and spatial Wilson loop, the Polyakov loop and the 't Hooft loop. Next the dual Meißner effect, which assumes a condensate of magnetic monopoles, will be explained as a picture of confinement. I will also show how magnetic monopoles arises in QCD after the so-called Abelian projection. The second lecture is devoted to the center vortex picture of confinement. Center vortices will be defined both on the lattice and in the continuum. Within the center vortex picture the emergence of the area law for the Wilson loop as well as the deconfinement phase transition at finite temperature will be explained. Furthermore, lattice evidence for the center vortex picture will be provided. Finally, I will discuss the topological properties of center vortices and their relation to magnetic monopoles. I will provide evidence from lattice calculations that center vortices are not only responsible for confinement but also for the spontaneous breaking of chiral symmetry. In the last lecture I will present the Hamiltonian approach to QCD in Coulomb gauge, which is then used to establish the Gribov--Zwanziger picture of confinement. Furthermore, I will also relate this scenario to the dual Meißner effect and the center vortex picture. Finally, I will study QCD at finite temperature within the Hamiltonian approach in a novel way by compactifying one spatial dimension. The Polyakov loop and the dual and chiral quark condensates will be evaluated as function of the temperature.

   ↳ hep-thhep-lathep-ph2 citations
6. 06*

   A Search for Dark Matter Annihilation in the Milky Way Halo

   Laura J. Chang🇺🇸 · Mariangela Lisanti🇺🇸 · Siddharth Mishra-Sharma🇺🇸

   The Milky Way halo is the brightest source of dark matter annihilation on the sky. Indeed, the potential strength of the Galactic dark matter signal can supersede that expected from dwarf galaxies and galaxy groups even in regions away from the Inner Galaxy. In this paper, we present the results of a search for dark matter annihilation in the smooth Milky Way halo for $|b|>20^{\circ }$ and $r<50^{\circ }$ using 413 weeks of Fermi Pass 8 data within the energy range of $\sim$0.8-50 GeV. We exclude thermal dark matter with mass below $\sim$70 GeV that annihilates to $b\bar{b}$ at the 95% confidence level using the p6v11 cosmic-ray foreground model, providing the strongest limits on the annihilation cross section in this mass range. These results exclude the region of dark matter parameter space that is consistent with the excess of $\sim$GeV photons observed at the Galactic Center for the $b\bar{b}$ annihilation channel and, for the first time, start probing the ${\tau }^{+}{\tau }^{-}$ explanation. We explore how these results depend on uncertainties in the foregrounds by varying over a set of reasonable models.

   ↳ astro-ph.COastro-ph.HEhep-phPRD(2018)·59 citations
7. 07*

   Radial flow in a multi phase transport model at FAIR energies

   Soumya Sarkar🇮🇳 · Provash Mali🇮🇳 · Somnath Ghosh🇮🇳 · Amitabha Mukhopadhyay🇮🇳

   Azimuthal distributions of radial velocities of charged hadrons produced in nucleus-nucleus $(AB)$ collisions are compared with the corresponding azimuthal distribution of charged hadron multiplicity in the framework of a multiphase transport (AMPT) model at two different collision energies. The mean radial velocity seems to be a good probe for studying radial expansion. While the anisotropic part of the distributions indicates a kind of collective nature of radial expansion, the isotropic part characterizes a thermal motion. The present investigation is carried out keeping the upcoming Compressed Baryonic Matter (CBM) experiment to be held at the Facility for Anti-proton Ion Research (FAIR) in mind. As far as high-energy heavy-ion interactions are concerned, CBM will supplement the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) experiments. In this context our simulation results at high baryochemical potential would be interesting, when scrutinized from the perspective of almost a baryon free environment achieved at RHIC and LHC.

   ↳ nucl-thhep-phAdv.High Energy Phys.(2018)·1 citation
8. 08*

   Universal deformation of particle momenta space in perturbation theory

   Stanislav Srednyak🇺🇸

   We define an embedding of the space of complex momenta and masses in perturbation theory into a universal projective space. This embedding is natural in the sense of properties of the vector bundle defined by Feynman integrals on the complement to Landau varieties. We point out that there is a holonomic D-module associated with individual Feynman integrals. We quote explicit generators for this D-module on the fully deformed space of particle momenta. This basis is quadratic in the derivatives. We conclude that there is holonomic D-module on the physical space of momenta.

   ↳ hep-thhep-ph2 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.