Thu·Sep 21, 2017Thursday·September 21, 2017

1. 01*

   Flavor structure from misalignment of inner products in noncommutative geometry

   Masaki J. S. Yang🇯🇵

   In this letter, we consider an idea that induces flavor structure from inner products in noncommutative geometry. Assuming proper components of vectors $v_{(L,R)i}$ in enlarged representation space for fermions, we can induce the waterfall texture for Yukawa matrices retaining gauge interactions are universal. The hierarchy of the Yukawa interactions is a consequence of "misalignment" between the vectors $v_{Li}$ and $v_{Rj}$.

   hep-phJHEP(2018)·1 citation
2. 02*

   Non-standard neutrino self-interactions in a supernova and fast flavor conversions

   Amol Dighe🇮🇳 · Manibrata Sen (Tata Inst.)🇮🇳

   We study the effects of non-standard self-interactions (NSSI) of neutrinos streaming out of a core-collapse supernova. We show that with NSSI, the standard linear stability analysis gives rise to linearly as well as exponentially growing solutions. For a two-box spectrum, we demonstrate analytically that flavor-preserving NSSI lead to a suppression of bipolar collective oscillations. In the intersecting four-beam model, we show that flavor-violating NSSI can lead to fast oscillations even when the angle between the neutrino and antineutrino beams is obtuse, which is forbidden in the Standard Model. This leads to the new possibility of fast oscillations in a two-beam system with opposing neutrino-antineutrino fluxes, even in the absence of any spatial inhomogeneities. Finally, we solve the full non-linear equations of motion in the four-beam model numerically, and explore the interplay of fast and slow flavor conversions in the long-time behavior, in the presence of NSSI.

   hep-phastro-ph.HEastro-ph.SRPRD(2018)·48 citations
3. 03*

   $t\bar{t}b\bar{b}$ hadroproduction with massive bottom quarks with PowHel

   G. Bevilacqua🇭🇺 · M.V. Garzelli🇩🇪 · A. Kardos🇭🇺

   The associated production of top-antitop-bottom-antibottom quarks is a relevant irreducible background for Higgs boson analyses in the top-antitop-Higgs production channel, with Higgs decaying into a bottom-antibottom quark pair. We implement this process in the PowHel event generator, considering the bottom quarks as massive in all steps of the computation which involves hard-scattering matrix-elements in the 4-flavour number scheme combined with 4-flavour Parton Distribution Functions. Predictions with NLO QCD + Parton Shower accuracy, as obtained by PowHel + PYTHIA, are compared to those which resulted from a previous PowHel implementation with hard-scattering matrix-elements in the 5-flavour number scheme, considering as a baseline the example of a realistic analysis of top-antitop hadroproduction with additional $b$-jet activity, performed by the CMS collaboration at the Large Hadron Collider.

   hep-ph50 citations
4. 04*

   Top-pair and $tW$ production at approximate N${}^3$LO

   Nikolaos Kidonakis🇺🇸

   I present approximate N${}^3$LO theoretical results for top-antitop pair production, and for single-top production in association with a $W$ boson. The higher-order corrections are from soft-gluon radiation, which is dominant near partonic threshold. I present results for total cross sections as well as transverse-momentum and rapidity distributions of the top quark, and compare with data at LHC energies.

   hep-ph2 citations
5. 05*

   Charged Higgs production with a $W$ boson via $b$-quark annihilation

   Nikolaos Kidonakis🇺🇸

   I present theoretical calculations for charged Higgs production in association with a $W$ boson via bottom quark annihilation. I discuss higher-order radiative corrections from collinear and soft gluon emission and show that they are important. I present theoretical results for total cross sections, and for transverse-momentum and rapidity distributions of the charged Higgs boson at LHC energies.

   hep-ph1 citation
6. 06*

   Thermal Dark Matter Through the Dirac Neutrino Portal

   Brian Batell🇺🇸 · Tao Han🇺🇸 · David McKeen🇺🇸 · Barmak Shams Es Haghi🇺🇸

   We study a simple model of thermal dark matter annihilating to standard model neutrinos via the neutrino portal. A (pseudo-)Dirac sterile neutrino serves as a mediator between the visible and the dark sectors, while an approximate lepton number symmetry allows for a large neutrino Yukawa coupling and, in turn, efficient dark matter annihilation. The dark sector consists of two particles, a Dirac fermion and complex scalar, charged under a symmetry that ensures the stability of the dark matter. A generic prediction of the model is a sterile neutrino with a large active-sterile mixing angle that decays primarily invisibly. We derive existing constraints and future projections from direct detection experiments, colliders, rare meson and tau decays, electroweak precision tests, and small scale structure observations. Along with these phenomenological tests, we investigate the consequences of perturbativity and scalar mass fine tuning on the model parameter space. A simple, conservative scheme to confront the various tests with the thermal relic target is outlined, and we demonstrate that much of the cosmologically-motivated parameter space is already constrained. We also identify new probes of this scenario such as multi-body kaon decays and Drell-Yan production of $W$ bosons at the LHC.

   hep-phastro-ph.COhep-exPRD(2018)·130 citations
7. 07*

   Hidden Sector Dark Matter and the Galactic Center Gamma-Ray Excess: A Closer Look

   Miguel Escudero🇪🇸 · Samuel J. Witte🇪🇸 · Dan Hooper🇺🇸

   Stringent constraints from direct detection experiments and the Large Hadron Collider motivate us to consider models in which the dark matter does not directly couple to the Standard Model, but that instead annihilates into hidden sector particles which ultimately decay through small couplings to the Standard Model. We calculate the gamma-ray emission generated within the context of several such hidden sector models, including those in which the hidden sector couples to the Standard Model through the vector portal (kinetic mixing with Standard Model hypercharge), through the Higgs portal (mixing with the Standard Model Higgs boson), or both. In each case, we identify broad regions of parameter space in which the observed spectrum and intensity of the Galactic Center gamma-ray excess can easily be accommodated, while providing an acceptable thermal relic abundance and remaining consistent with all current constraints. We also point out that cosmic-ray antiproton measurements could potentially discriminate some hidden sector models from more conventional dark matter scenarios.

   hep-phastro-ph.COastro-ph.HEJCAP(2017)·41 citations
8. 08*

   Bound on dissipative effects from semileptonic neutral B-meson decays

   F. Benatti🇮🇹 · R. Floreanini🇮🇹 · S. Marcantoni🇮🇹 · P. Pinotti🇮🇹 · K. Zimmermann🇮🇹

   The semileptonic decay asymmetry ${\mathcal{A}}_{\Delta m}$ is studied within the open quantum systems approach to the physics of the neutral meson $B^0$-$\overline{B^0}$ system: this extended treatment takes into account possible non-standard, dissipative effects induced by the presence of an external environment. A bound on these effects is provided through the analysis of available experimental data from the Belle Collaboration.

   hep-phquant-phEPJC(2017)·3 citations
9. 09*

   The Toric SO(10) F-Theory Landscape

   Wilfried Buchmuller🇩🇪 · Markus Dierigl🇩🇪 · Paul-Konstantin Oehlmann🇩🇪 · Fabian Ruehle🇬🇧

   Supergravity theories in more than four dimensions with grand unified gauge symmetries are an important intermediate step towards the ultraviolet completion of the Standard Model in string theory. Using toric geometry, we classify and analyze six-dimensional F-theory vacua with gauge group SO(10) taking into account Mordell-Weil U(1) and discrete gauge factors. We determine the full matter spectrum of these models, including charged and neutral SO(10) singlets. Based solely on the geometry, we compute all matter multiplicities and confirm the cancellation of gauge and gravitational anomalies independent of the base space. Particular emphasis is put on symmetry enhancements at the loci of matter fields and to the frequent appearance of superconformal points. They are linked to non-toric Kähler deformations which contribute to the counting of degrees of freedom. We compute the anomaly coefficients for these theories as well by using a base-independent blow-up procedure and superconformal matter transitions. Finally, we identify six-dimensional supergravity models which can yield the Standard Model with high-scale supersymmetry by further compactification to four dimensions in an Abelian flux background.

   ↳ hep-thhep-phJHEP(2017)·27 citations
10. 10*

    Neutron star mergers as a probe of modifications of general relativity with finite-range scalar forces

    Laura Sagunski🇨🇦 · Jun Zhang🇨🇦 · Matthew C. Johnson🇨🇦 · Luis Lehner🇨🇦 · Mairi Sakellariadou🇬🇧 · Steven L. Liebling🇺🇸 · Carlos Palenzuela🇪🇸 · David Neilsen🇺🇸

    Observations of gravitational radiation from compact binary systems provide an unprecedented opportunity to test General Relativity in the strong field dynamical regime. In this paper, we investigate how future observations of gravitational radiation from binary neutron star mergers might provide constraints on finite-range forces from a universally coupled massive scalar field. Such scalar degrees of freedom are a characteristic feature of many extensions of General Relativity. For concreteness, we work in the context of metric $f(R)$ gravity, which is equivalent to General Relativity and a universally coupled scalar field with a non-linear potential whose form is fixed by the choice of $f(R)$. In theories where neutron stars (or other compact objects) obtain a significant scalar charge, the resulting attractive finite-range scalar force has implications for both the inspiral and merger phases of binary systems. We first present an analysis of the inspiral dynamics in Newtonian limit, and forecast the constraints on the mass of the scalar and charge of the compact objects for the Advanced LIGO gravitational wave observatory. We then perform a comparative study of binary neutron star mergers in General Relativity with those of a one-parameter model of $f(R)$ gravity using fully relativistic hydrodynamical simulations. These simulations elucidate the effects of the scalar on the merger and post-merger dynamics. We comment on the utility of the full waveform (inspiral, merger, post-merger) to probe different regions of parameter space for both the particular model of $f(R)$ gravity studied here and for finite-range scalar forces more generally.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2018)·102 citations
11. 11*

    The anisotropic non-equilibrium hydrodynamic attractor

    Michael Strickland🇺🇸 · Jorge Noronha🇧🇷 · Gabriel Denicol🇧🇷

    We determine the dynamical attractors associated with anisotropic hydrodynamics (aHydro) and the DNMR equations for a 0+1d conformal system using kinetic theory in the relaxation time approximation. We compare our results to the non-equilibrium attractor obtained from exact solution of the 0+1d conformal Boltzmann equation, Navier-Stokes theory, and second-order Mueller-Israel-Stewart theory. We demonstrate that the aHydro attractor equation resums an infinite number of terms in the inverse Reynolds number. The resulting resummed aHydro attractor possesses a positive longitudinal to transverse pressure ratio and is virtually indistinguishable from the exact attractor. This suggests that kinetic theory involves not only a resummation in gradients (Knudsen number) but also a novel resummation in inverse Reynolds number. We also demonstrate that the DNMR result provides a better approximation to the exact kinetic theory attractor than Mueller-Israel-Stewart theory. Finally, we introduce a new method for obtaining approximate aHydro equations which relies solely on an expansion in inverse Reynolds number, carry out this expansion to third order, and compare these third-order results to the exact kinetic theory solution.

    ↳ nucl-thhep-phPRD(2018)·180 citations
12. 12*

    Asymptotic safety guaranteed in supersymmetry

    Andrew D. Bond🇬🇧 · Daniel F. Litim🇬🇧

    We explain how asymptotic safety arises in four-dimensional supersymmetric gauge theories. We provide asymptotically safe supersymmetric gauge theories together with their superconformal fixed points, R-charges, phase diagrams, and UV-IR connecting trajectories. Strict perturbative control is achieved in a Veneziano limit. Consistency with unitarity and the a-theorem is established. We find that supersymmetry enhances the predictivity of asymptotically safe theories.

    ↳ hep-thhep-phPRL(2017)·51 citations
13. 13*

    Monodromy inflation at strong coupling: $4\pi$ in the sky

    Guido D'Amico🇨🇭 · Nemanja Kaloper🇺🇸 · Albion Lawrence🇺🇸

    We present a simple effective field theory formulation of a general family of single field flux monodromy models for which strong coupling effects at large field values can flatten the potential and activate operators with higher powers of derivatives. These models are radiatively and non-perturbatively stable and can easily sustain $\text{ga}60$ efolds of inflation. The dynamics combines features of both large field chaotic inflation and $k$-inflation, both of which can suppress the tensor amplitude. Reducing the tensor-scalar ratio below the observational bound $r\lesssim 0.1$ while keeping the scalar spectral index $n_s$ within experimental bounds either yields equilateral nongaussianity $f_{NL}^{eq}\simeq \mathcal{O}(1)$, close to the current observational bounds, or ultimately gives very small $r$.

    ↳ hep-thastro-ph.COgr-qchep-phPRL(2018)·42 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.