Tue·May 22, 2018Tuesday·May 22, 2018

1. 01*

   Energetic $\gamma$-rays from TeV scale dark matter annihilation resummed

   M. Beneke🇩🇪 · A. Broggio🇩🇪 · C. Hasner🇩🇪 · M. Vollmann🇩🇪

   The annihilation cross section of TeV scale dark matter particles ${\chi }^0$ with electroweak charges into photons is affected by large quantum corrections due to Sudakov logarithms and the Sommerfeld effect. We calculate the semi-inclusive photon energy spectrum in ${\chi }^0{\chi }^0\to \gamma +X$ in the vicinity of the maximal photon energy $E_{\gamma }=m_{\chi }$ with NLL' accuracy in an all-order summation of the electroweak perturbative expansion adopting the pure wino model. This results in the most precise theoretical prediction of the annihilation rate for $\gamma$-ray telescopes with photon energy resolution of parametric order $m_W^2/m_{\chi }$ for photons with TeV energies.

   hep-phastro-ph.HEPLB(2018)·43 citations
2. 02*

   White Dwarfs as Dark Matter Detectors

   Peter Graham🇺🇸 · Ryan Janish🇺🇸 · Vijay Narayan🇺🇸 · Surjeet Rajendran🇺🇸 · Paul Riggins🇺🇸

   Dark matter that is capable of sufficiently heating a local region in a white dwarf will trigger runaway fusion and ignite a type Ia supernova. This was originally proposed in Graham et al. (2015) and used to constrain primordial black holes which transit and heat a white dwarf via dynamical friction. In this paper, we consider dark matter (DM) candidates that heat through the production of high-energy standard model (SM) particles, and show that such particles will efficiently thermalize the white dwarf medium and ignite supernovae. Based on the existence of long-lived white dwarfs and the observed supernovae rate, we derive new constraints on ultra-heavy DM which produce SM particles through DM-DM annihilations, DM decays, and DM-SM scattering interactions in the stellar medium. As a concrete example, we rule out supersymmetric Q-ball DM in parameter space complementary to terrestrial bounds. We put further constraints on DM that is captured by white dwarfs, considering the formation and self-gravitational collapse of a DM core which heats the star via decays and annihilations within the core. It is also intriguing that the DM-induced ignition discussed in this work provide an alternative mechanism of triggering supernovae from sub-Chandrasekhar, non-binary progenitors.

   hep-phPRD(2018)·110 citations
3. 03*

   The line shapes of the $Z_b(10610)$ and $Z_b(10650)$ in the elastic and inelastic channels revisited

   Q. Wang🇩🇪 · V. Baru🇩🇪 · A. A. Filin🇩🇪 · C. Hanhart🇩🇪 · A. V. Nefediev🇷🇺 · J.-L. Wynen🇩🇪

   The most recent experimental data for all measured production and decay channels of the bottomonium-like states $Z_b(10610)$ and $Z_b(10650)$ are analysed simultaneously using solutions of the Lippmann-Schwinger equations which respect constraints from unitarity and analyticity. The interaction potential in the open-bottom channels $B^{(\ast )}{\bar{B}}^{\ast }+\text{mbox}c.c.$ contains short-range interactions as well as one-pion exchange. It is found that the long-range interaction does not affect the line shapes as long as only $S$ waves are considered. Meanwhile, the line shapes can be visibly modified once $D$ waves, mediated by the strong tensor forces from the pion exchange potentials, are included. However, in the fit they get balanced largely by a momentum dependent contact term that appears to be needed also to render the results for the line shapes independent of the cut-off. The resulting line shapes are found to be insensitive to various higher-order interactions included to verify stability of the results. Both $Z_b$ states are found to be described by the poles located on the unphysical Riemann sheets in the vicinity of the corresponding thresholds. In particular, the $Z_b(10610)$ state is associated with a virtual state residing just below the $B{\bar{B}}^{\ast }/\bar{B}{B}^{\ast }$ threshold while the $Z_b(10650)$ state most likely is a shallow state located just above the $B^{\ast }{\bar{B}}^{\ast }$ threshold.

   hep-phhep-exnucl-thPRD(2018)·85 citations
4. 04*

   ${ϵ}^{\prime }/ϵ$ from charged-Higgs-induced gluonic dipole operators

   Chuan-Hung Chen🇹🇼 · Takaaki Nomura🇰🇷

   We study the effect of charged-Higgs-induced chromomagnetic operator, $Q_{8G}(-)\equiv \bar{s}{\sigma }^{\mu \nu }{T}^a{\gamma }_{5}d{G}_{\mu \nu }^a$, on the Kaon direct CP violation $Re({ϵ}^{\prime }/ϵ)$. Using the matrix element $⟨\pi \pi |O_{8G}(-)|K^0⟩$ recently obtained by a large $N_c$ dual QCD approach, we find that if the Kobayashi-Maskawa phase is the origin of CP violation, the charged-Higgs-induced gluon penguin dipole operator in the type-III two-Higgs-doublet model can explain the measured $Re({ϵ}^{\prime }/ϵ)$ when the constraints from the relevant low energy flavor physics, such as $\Delta B(K)=2$, $B\to X_s\gamma$, and Kaon indirect CP violation parameter $ϵ$, are included.

   hep-phhep-exPLB(2018)·24 citations
5. 05*

   Addressing the Majorana vs. Dirac Question Using Neutrino Decays

   Boris Kayser🇺🇸

   We explain why it is so hard to determine whether neutrinos are Majorana or Dirac particles as long as the only neutrinos we study are ultra-relativistic. We then show how non-relativistic neutrinos could help, and focus on the angular distributions in the decays of an as-yet-to-be-discovered heavy neutrino $N$. We find that these angular distributions could very well tell us whether neutrinos are Majorana or Dirac particles.

   hep-ph3 citations
6. 06*

   Dynamically assisted Schwinger effect beyond the spatially-uniform-field approximation

   I. A. Aleksandrov🇷🇺 · G. Plunien🇩🇪 · V. M. Shabaev🇷🇺

   We investigate the phenomenon of electron-positron pair production from vacuum in the presence of a strong electric field superimposed by a weak but fast varying pulse which substantially increases the total particle yield. We employ a nonperturbative numerical technique and perform the calculations beyond the spatially-uniform-field approximation, i.e. dipole approximation, taking into account the coordinate dependence of the fast component. The analysis of the main characteristics of the pair-production process (momentum spectra of particles and total amount of pairs) reveals a number of important features which are absent within the previously used approximation. In particular, the structure of the momentum distribution is modified both qualitatively and quantitatively, and the total number of pairs created as well as the enhancement factor due to dynamical assistance become significantly smaller.

   hep-phPRD(2018)·56 citations
7. 07*

   Vacuum alignment in a composite 2HDM

   Chengfeng Cai🇨🇳 · Giacomo Cacciapaglia🇫🇷 · Hong-Hao Zhang🇨🇳

   We study in detail the vacuum structure of a composite two Higgs doublet model based on a minimal underlying theory with 3 Dirac fermions in pseudo-real representations of the condensing gauge interactions, leading to the SU(6)/Sp(6) symmetry breaking pattern. We find that, independently on the source of top mass, the most general CP-conserving vacuum is characterised by three non-vanishing angles. A special case occurs if the Yukawas are aligned, leading to a single angle. In the latter case, a Dark Matter candidate arises, protected by a global U(1) symmetry.

   hep-phJHEP(2019)·53 citations
8. 08*

   Spin structure of heavy-quark hybrids

   Nora Brambilla🇩🇪 · Wai Kin Lai🇩🇪 · Jorge Segovia🇪🇸 · Jaume Tarrús Castellà🇪🇸 · Antonio Vairo🇩🇪

   A unique feature of quantum chromodynamics (QCD), the theory of strong interactions, is the possibility for gluonic degrees of freedom to participate in the construction of physical hadrons, which are color singlets, in an analogous manner to valence quarks. Hadrons with no valence quarks are called glueballs, while hadrons where both gluons and valence quarks combine to form a color singlet are called hybrids. The unambiguous identification of such states among the experimental hadron spectrum has been thus far not possible. Glueballs are particularly difficult to establish experimentally since the lowest lying ones are expected to strongly mix with conventional mesons. On the other hand, hybrids should be easier to single out because the set of quantum numbers available to their lowest excitations may be exotic, i.e., not realized in conventional quark-antiquark systems. Particularly promising for discovery appear to be heavy hybrids, which are made of gluons and a heavy-quark-antiquark pair (charm or bottom). In the heavy-quark sector systematic tools can be used that are not available in the light-quark sector. In this paper we use a nonrelativistic effective field theory to uncover for the first time the full spin structure of heavy-quark hybrids up to $1/m^2$-terms in the heavy-quark-mass expansion. We show that such terms display novel characteristics at variance with our consolidated experience on the fine and hyperfine splittings in atomic, molecular and nuclear physics. We determine the nonperturbative contributions to the matching coefficients of the effective field theory by fitting our results to lattice-QCD determinations of the charmonium hybrid spectrum and extrapolate the results to the bottomonium hybrid sector where lattice-QCD determinations are still challenging.

   hep-phhep-latnucl-thPRD(2019)·90 citations
9. 09*

   On a possibility of exotic heavy baryons

   Michal Praszalowicz🇵🇱

   Triggered by a recent announcement by the LHCb Collaboration of five excited ${\Omega }_c^0$ resonances of small widths we propose an interpretation based on the Chiral Quark Soliton Model. We argue that three of the LHCb resonances are parity ($-$) excitations of the ground state SU(3) sextets, while the other two with the smallest widths are exotic pentaquarks that belong to the SU(3) $\overline{15}$. We first briefly review the model and discuss the status of the putative ${\Theta }^{+}(1540)$. Next we show how to generalize the model to the case of heavy baryons. We test this approach against the ground state $\overline{3}$ and $6$ heavy baryons, and discuss different excitations that are possible in the Chiral Quark Soliton Model. We show that the model accommodates two excited $\overline{3}$ in the charm sector that are experimentally observed. Finally we discuss possible assignments of the LHCb ${\Omega }_c^0$ states.

   hep-phPoS(2018)·6 citations
10. 10*

    Double and triple inclusive gluon production at mid rapidity: quantum interference in p-A scattering

    Tolga Altinoluk🇵🇱 · Néstor Armesto🇪🇸 · Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱

    We compute double and triple inclusive gluon production in p-A scattering beyond the so-called "glasma graph" approximation. We consider quantum interference effects and identify in this general setup the terms responsible for the gluon HBT and initial wave function Bose enhancement which lead to correlations in particle production. Both of these terms originate from the factorizable part of the quadrupole and sextupole terms in the production cross section. We also show that the target Bose enhancement in this regime is suppressed at large number of colors.

    hep-phEPJC(2018)·34 citations
11. 11*

    EKHARA 3.0: an update of the EKHARA Monte Carlo event generator

    Henryk Czyz🇵🇱 · Patrycja Kisza🇵🇱

    The Monte Carlo event generator EKHARA was upgraded during last years. The upgrades presented here contain: a) the inclusion of new final states $e^{+}{e}^{-}\to e^{+}{e}^{-}\eta$, $e^{+}{e}^{-}\to e^{+}{e}^{-}{\eta }^{\prime }$, $e^{+}{e}^{-}\to e^{+}{e}^{-}{\chi }_{c_i}$ and $e^{+}{e}^{-}\to e^{+}{e}^{-}{\chi }_{c_i}(\to J/\psi (\to {\mu }^{+}{\mu }^{-})\gamma )$; b) new ${\gamma }^{\ast }-{\gamma }^{\ast }-P$ transition form factors and c) the radiative corrections to the reactions $e^{+}{e}^{-}\to e^{+}{e}^{-}P$. For the upgrades a) and b), we present here only the pieces missing in other publications, mostly algorithms used in the phase space generation. The radiative corrections are presented here for the first time. A new algorithm of the phase space generation for the reaction $e^{+}{e}^{-}\to e^{+}{e}^{-}P\gamma$ being its main part. A comparison with GGRESRC generator is presented. Big differences between the radiative corrections calculated by the EKHARA and the GGRESRC generators are observed.

    hep-phhep-exComput.Phys.Commun.(2019)·26 citations
12. 12*

    Probing anomalous $Wtb$ couplings at the LHC in single top quark production through $t$-channel

    Adil Jueid🇨🇳

    We study the sensitivity of certain observables to the anomalous right tensorial coupling in single top production at the LHC at $\sqrt{s}=13\text{ TeV}$. The observables consist of asymmetries constructed from the energy and angles of the decay products of the top quark produced in single top production through $t$-channel. The computation is done at Leading Order (LO) and Next-to-Leading Order (NLO) in the strong coupling in the $5$ flavor scheme. We have estimated projected limits on the anomalous coupling, both at the parton level without cuts and at the particle level with cuts. We find that the asymmetries are robust with respect to the higher order QCD corrections and are indeed a very good probe of this anomalous coupling of the top. Hence they can be used as experimental probes of the same.

    hep-phPRD(2018)·22 citations
13. 13*

    Nearly right unitarity triangle and CP phase in quark and lepton flavor mixings

    Yukihiro Mimura🇹🇼

    The nearly right unitarity triangle can be simply obtained if a quark mass matrix is written as a linear combination of real rank-1 matrices and the coefficient which gives the mass of the second generation is pure imaginary. Supposing that the source of the CP violation is in the Yukawa coupling to an additional Higgs field which provides a factor for the strange quark and muon mass ratio, we obtain that the angle $\alpha ={\varphi }_2$ of the unitarity triangle shifts from $90^{\mathrm{o}}$ by units of $V_{ub}/V_{us}$, and is postdicted as $\alpha \simeq 87^{\mathrm{o}}$ or $91^{\mathrm{o}}$. The Dirac CP phase $\delta$ which appears in the three-flavor neutrino oscillations is obtained to be $|\delta |\simeq 80^{\mathrm{o}}$ if the neutrino mass matrix gives tri-bimaximal-like mixing form. If the factor 3 for the muon and strange quark mass is considered in a simple manner in the quark-lepton unification, we obtain three distinctive prediction of $\delta$ for nearly right-angled phase as $|\delta |\simeq 70^{\mathrm{o}}$, $90^{\mathrm{o}}$, or $110^{\mathrm{o}}$ in an idealistic orthogonal structure of the neutrino mass matrix. The deviation from $90^{\mathrm{o}}$ is roughly given by $\arcsin (1/3)$ by inputting the experimental measurements.

    hep-ph2 citations
14. 14*

    Bound-state double-$\beta$ decay

    A. Babič🇨🇿 · D. Štefánik🇸🇰 · M. I. Krivoruchenko🇷🇺 · F. Šimkovic🇸🇰

    We consider new modes of two-neutrino and neutrinoless double-$\beta$ decays in which one $\beta$ electron goes over to a continuous spectrum and the other occupies a vacant bound level of the daughter ion. We calculate the corresponding phase-space factors of the final states, estimate the partial decay rates, and derive the one- and two-electron energy spectra using relativistic many-electron wave functions of atoms provided by the multiconfiguration Dirac-Hartree-Fock package GRASP2K. While the bound-state neutrinoless double-$\beta$ decays are strongly suppressed, their two-neutrino counterparts can be observed in the next-generation double-$\beta$-decay experiments, most notably SuperNEMO.

    hep-phPRC(2018)·7 citations
15. 15*

    Magnetic skyrmions as host of neutrino mass spectroscopy

    M.Yoshimura🇯🇵

    Large magneto-electric effect in multi-ferroics and topological protection against decays of excited magnetic skyrmions are an ideal setting for detecting radiative emission of neutrino pair (RENP). We propose a new RENP scheme using multi-ferroic magnetic skyrmion condensates in order to determine the absolute neutrino mass including the mass hierarchy patterns, the type of neutrino mass (Majorana vs Dirac), one of CP violation parameters, and to detect relic 1.9 K cosmic neutrino. We critically examine the possibility of feasible experiments, and show what are required as good targets for neutrino physics.

    hep-phcond-mat.mtrl-scihep-ex0 citations
16. 16*

    Effects of heavy neutrinos on vacuum stability in two-Higgs-doublet model with GUT scale supersymmetry

    V Suryanarayana Mummidi🇮🇳 · Vishnu P. K.🇮🇳 · Ketan M. Patel🇮🇳

    We analyse the implications of right-handed neutrinos on the stability of the electroweak vacuum in two-Higgs-doublet models with supersymmetry at high scale. It is assumed that supersymmetry is broken at scale $M_S=2\times 10^{16}$ GeV and effective theory below $M_S$ is two-Higgs-doublet model of type II with three generations of singlet neutrinos which induce small masses for the standard model neutrinos through type I seesaw mechanism. We study the high and low scale versions of seesaw mechanism. In both these cases, we show that the presence of right-handed neutrinos significantly improves the stability of electroweak vacuum if their Yukawa couplings with the SM leptons are of $\mathcal{O}(1)$ or greater. However, this possibility is severely constrained by the measured mass and couplings of Higgs and limits on the mass of the charged Higgs from the flavour physics data. It is shown that the stable or metastable electroweak vacuum and experimentally viable low energy scalar spectrum require $\tan \beta \text{lsim}2.5$ and the magnitude of neutrino Yukawa couplings smaller than $\mathcal{O}(1)$. The results obtained in this case are qualitatively similar to those without right-handed neutrinos.

    hep-phJHEP(2018)·11 citations
17. 17*

    SO(3) family symmetry and axions

    Mario Reig🇪🇸 · José W.F. Valle🇪🇸 · Frank Wilczek🇺🇸

    Motivated by the idea of comprehensive unification, we study a gauged SO(3) flavor extension of the extended Standard Model, including right-handed neutrinos and a Peccei-Quinn symmetry with simple charge assignments. The model accommodates the observed fermion masses and mixings and yields a characteristic, successful relation among them. The Peccei-Quinn symmetry is an essential ingredient.

    hep-phPRD(2018)·42 citations
18. 18*

    Kinetic Mixing, Dark Photons and Extra Dimensions II: Fermionic Dark Matter

    Thomas G. Rizzo🇺🇸

    Extra dimensions can be very useful tools when constructing new physics models. Previously, we began investigating toy models for the 5-D analog of the kinetic mixing/vector portal scenario where the interactions of bulk dark matter with the brane-localized fields of the Standard Model are mediated by a massive $U(1{)}_D$ dark photon also living in the bulk. In that setup, where the dark matter was taken to be a complex scalar, a number of nice features were obtained such as $U(1{)}_D$ breaking by boundary conditions without the introduction of a dark Higgs field, the absence of potentially troublesome SM Higgs-dark singlet mixing, also by boundary conditions, the natural similarity of the dark matter and dark photon masses and the decoupling of the heavy gauge Kaluza-Klein states from the Standard Model. In the present paper we extend this approach by examining the more complex cases of Dirac and Majorana fermionic dark matter. In particular, we discuss a new mechanism that can occur in 5-D (but not in 4-D) that allows for light Dirac dark matter in the $\sim 100$ MeV mass range, even though it has an $s$-wave annihilation into Standard Model fields, by avoiding the strong constraints that arise from both the CMB and 21 cm data. This mechanism makes use of the presence of the Kaluza-Klein excitations of the dark photon to extremize the increase in the annihilation cross section usually obtained via resonant enhancement. In the Majorana dark matter case, we explore the possibility of a direct $s$-channel dark matter pair-annihilation process producing the observed relic density, due to the general presence of parity-violating dark matter interactions, without employing the usual co-annihilation mechanism which is naturally suppressed in this 5-D setup.

    hep-phJHEP(2018)·35 citations
19. 19*

    Theory of flavors: String compactification

    Jihn E. Kim🇰🇷

    We present a calculating method for the quark and lepton mixing angles. After a general discussion in field theoretic models, we present a working model from a string compactification through $Z_{12-I}$ orbifold compactification. It is beyond presenting just three families of the standard model but is the first example from string compactification successfully fitting to the observed data. Assuming that all Yukawa couplings from string compactification are real, we also comment on a relation between the CP phases in the Jarlskog determinants obtained from the CKM and PMNS matrices. The flipped SU(5) model leads to the doublet-triplet splitting and possible proton decay operators. It is shown that the vacuum expectation values can be tuned such that the proton lifetime is long enough.

    hep-phhep-thPRD(2018)·8 citations
20. 20*

    The strong coupling from $e^{+}{e}^{-}\to$ hadrons below charm

    Diogo Boito🇧🇷 · Maarten Golterman🇺🇸 · Alexander Keshavarzi🇬🇧 · Kim Maltman🇨🇦 · Daisuke Nomura🇯🇵 · Santiago Peris🇪🇸 · Thomas Teubner🇬🇧

    We use a new compilation of the hadronic $R$-ratio from available data for the process $e^{+}{e}^{-}\to \text{mbox}hadrons$ to determine the strong coupling, ${\alpha }_s$. We make use of all data for the $R$-ratio from threshold to a center-of-mass energy of 2 GeV by employing finite-energy sum rules. Data above 2 GeV, for which at present far fewer high-precision experimental data are available, do not provide much additional constraint but are fully consistent with the values for ${\alpha }_s$ we obtain. Quoting our results at the $\tau$ mass to facilitate comparison to the results obtained from analogous analyses of hadronic $\tau$-decay data, we find ${\alpha }_s(m_{\tau }^2)=0.298\pm 0.016\pm 0.006$ in fixed-order perturbation theory, and ${\alpha }_s(m_{\tau }^2)=0.304\pm 0.018\pm 0.006$ in contour-improved perturbation theory, where the first error is statistical, and the second error reflects our estimate of various systematic effects. These values are in good agreement with a recent determination from the OPAL and ALEPH data for hadronic $\tau$ decays.

    hep-phhep-exhep-latPRD(2018)·47 citations
21. 21*

    Towards a viable scalar interpretation of $R_{D^{(\ast )}}$

    Sean Fraser🇪🇪 · Carlo Marzo🇪🇪 · Luca Marzola🇪🇪 · Martti Raidal🇪🇪 · Christian Spethmann🇪🇪

    Recent measurements of semileptonic B-meson decays seemingly imply violations of lepton flavor universality beyond the Standard Model predictions. With three-level explanations based on extended Higgs sectors being strongly challenged by the measurements of the $B_c^{-}$ lifetime, new theories invoking leptoquark or vector fields appear as the only feasible answer. However, in this work we show that simple scalar extensions of the Standard Model still offer a possible solution to the $B$ physics puzzle, owing to sizeable loop-level corrections which mimic the effects of new vector contributions. Considering a simplified model characterised by a charged and a neutral scalar particle, we verify the compatibility of the observed $R_{D^{(\ast )}}$ signal with the relevant collider bounds. We also study an embedding of the simplified model into a three-Higgs-doublet framework, and investigate its main phenomenological constraints.

    hep-phPRD(2018)·31 citations
22. 22*

    Thermo-magnetic evolution of the QCD strong coupling

    Alejandro Ayala🇲🇽 · C. A. Dominguez🇿🇦 · Saul Hernandez-Ortiz🇲🇽 · L. A. Hernandez🇿🇦 · M. Loewe🇨🇱 · D. Manreza Paret🇲🇽 · R. Zamora🇨🇱

    We study the one-loop gluon polarization tensor at zero and finite temperature in the presence of a magnetic field, to extract the thermo-magnetic evolution of the strong coupling ${\alpha }_s$. We analyze four distinct regimes, to wit, the small and large field cases, both at zero and at high temperature. From a renormalization group analysis we show that at zero temperature, either for small or large magnetic fields, and for a fixed transferred momentum $Q^2$, ${\alpha }_s$ grows with the field strength with respect to its vacuum value. However, at high temperature and also for a fixed value of $Q^2$ we find two different cases: When the magnetic field is even larger than the squared temperature, ${\alpha }_s$ also grows with the field strength. On the contrary, when the squared temperature is larger than the magnetic field, a turnover behavior occurs and ${\alpha }_s$ decreases with the field strength. This thermo-magnetic behavior of ${\alpha }_s$ can help explain the inverse magnetic catalysis phenomenon found by lattice QCD calculations.

    hep-phhep-thnucl-thPRD(2018)·87 citations
23. 23*

    $b\to c\tau {\nu }_{\tau }$ Decays: A Catalogue to Compare, Constrain, and Correlate New Physics Effects

    Srimoy Bhattacharya🇮🇳 · Soumitra Nandi🇮🇳 · Sunando Kumar Patra🇮🇳

    In this article, we have predicted the standard model (SM) values of the asymmetric and angular observables in $B\to D^{(\ast )}\tau {\nu }_{\tau }$ decays, using the results of the new up-to-date analysis in $B\to D^{(\ast )}\ell {\nu }_{\ell }$. We have also revisited the SM prediction of the inclusive ratio ${\mathcal{R}}_{X_c}$, and have given its values in different schemes of the charm quark mass. This is the first analysis which includes all the known corrections in the SM. In addition, we have analysed the $b\to c\tau {\nu }_{\tau }$ decay modes in a model-independent framework of effective field theory beyond the standard model. Considering all the possible combinations of the effective operators in $b\to c\tau {\nu }_{\tau }$ decays and using the Akaike Information Criterion, we find out the scenarios which can best explain the available data on these channels. In the selected scenarios, best-fit values and correlations of the new parameters are extracted. Using these results, predictions are made on various observables in the exclusive and inclusive semitaunic $b\to c$ decays. The graphical correlations between these observables are shown, which are found to be useful in discriminating various new physics scenarios.

    hep-phhep-exEPJC(2019)·104 citations
24. 24*

    Pion condensation and phase diagram in the Polyakov-loop quark-meson model

    Prabal Adhikari🇺🇸 · Jens O. Andersen🇳🇴 · Patrick Kneschke🇳🇴

    We use the Polyakov-loop extended two-flavor quark-meson model as a low-energy effective model for QCD to study the phase diagram in the ${\mu }_I$--$T$ plane where ${\mu }_I$ is the isospin chemical potential. In particular, we focus on the Bose condensation of charged pions. At $T=0$, the onset of pion condensation is at ${\mu }_I=\frac{1}{2}{m}_{\pi }$ in accordance with exact results. The phase transition to a Bose-condensed phase is of second order for all values of ${\mu }_I$ and in the $O(2)$ universality class. The chiral critical line joins the critical line for pion condensation at a point whose position depends on the Polyakov-loop potential and the sigma mass. For larger values of ${\mu }_I$ these curves are on top of each other. The deconfinement line enters smoothly the phase with the broken $O(2)$ symmetry. We compare our results with recent lattice simulations and find overall good agreement.

    hep-phPRD(2018)·74 citations
25. 25*

    A Systematic Analysis of Perturbations for Hexagonal Mixing Matrix

    Sumit K. Garg🇮🇳

    We present a systematic analysis of perturbative Hexagonal(HG) mixing for describing recent global fit neutrino mixing data with normal and inverted hierarchy. The corrections to unperturbed mixing are parameterized in terms of small orthogonal rotations (R) with modified PMNS matrix of the forms \big($R_{\alpha \beta }^l\cdot V_{HG},V_{HG}\cdot R_{\alpha \beta }^r,V_{HG}\cdot R_{\alpha \beta }^r\cdot R_{\gamma \delta }^r,R_{\alpha \beta }^l\cdot R_{\gamma \delta }^l\cdot V_{HG}$,~$R_{\alpha \beta }^l\cdot V_{HG}\cdot R_{\gamma \delta }^r$\big ). Here $R_{\alpha \beta }^{l,r}$ is rotation in ij sector and $V_{HG}$ is unperturbed Hexagonal mixing matrix. The detailed numerical investigation of all possible cases is performed with scanning of parameter space using ${\chi }^2$ approach. We found that the perturbative schemes governed by single rotation are unable to fit the mixing angle data even at $3\sigma$ level. The mixing schemes which involves two rotation matrices, only \big($R_{12}^l\cdot R_{13}^l\cdot V_{HG}$, ~$R_{13}^l\cdot R_{12}^l\cdot V_{HG}$,~$R_{13}^l\cdot V_{HG}\cdot R_{12}^r$,~$R_{12}^l\cdot V_{HG}\cdot R_{12}^r$, ~$R_{13}^l\cdot V_{HG}\cdot R_{13}^r$\big ) are successful in fitting all neutrino mixing angles within $1\sigma$ range for normal hierarchy(NH). However for inverted hierarchy(IH), only $R_{13}^l\cdot V_{HG}\cdot R_{13}^r$ is most preferable as it can fit all mixing angles at $1\sigma$ level. The remaining perturbative cases are either excluded at 3$\sigma$ level or successful in producing mixing angles only at $2-3\sigma$ level. To study the impact of phase parameter, we also looked into CP violating effects for single rotation case. The predicted value of ${\delta }_{CP}$ lies in the range $39.0^{\circ }(40.4^{\circ })\le |{\delta }_{CP}|\le 78.7^{\circ }(79.2^{\circ })$ for $U_{12}^l\cdot V_{HM}$ and $U_{13}^l\cdot V_{HM}$ case with Normal(Inverted) Hierarchy.

    hep-phInt.J.Mod.Phys.A(2019)·4 citations
26. 26*

    Vortices in a generalized Maxwell-Higgs model with visible and hidden sectors

    D. Bazeia🇧🇷 · L. Losano🇧🇷 · M.A. Marques🇧🇷 · R. Menezes🇧🇷

    We investigate the presence of vortices in generalized Maxwell-Higgs models with a hidden sector. The model engenders $U(1)\times U(1)$ symmetry, in a manner that the sectors are coupled via the visible magnetic permeability depending only on the hidden scalar field. We develop a first order framework in which the hidden sector decouples from the visible one. We illustrate the results with two specific examples, that give rise to the presence of vortices with internal structure.

    ↳ hep-thhep-phAdv.Ser.Direct.High Energy Phys.(2019)·4 citations
27. 27*

    A Conformal Collider for Holographic CFTs

    Nima Afkhami-Jeddi🇺🇸 · Sandipan Kundu🇺🇸 · Amirhossein Tajdini🇺🇸

    We develop a formalism to study the implications of causality on OPE coefficients in conformal field theories with large central charge and a sparse spectrum of higher spin operators. The formalism has the interpretation of a new conformal collider-type experiment for these class of CFTs and hence it has the advantage of requiring knowledge only about CFT three-point functions. This is accomplished by considering the holographic null energy operator which was introduced in arXiv:1709.03597 as a generalization of the averaged null energy operator. Analyticity properties of correlators in the Regge limit imply that the holographic null energy operator is a positive operator in a subspace of the total CFT Hilbert space. Utilizing this positivity condition, we derive bounds on three-point functions $⟨T{O}_1{O}_2⟩$ of the stress tensor with various operators for CFTs with large central charge and a sparse spectrum. After imposing these constraints, we also find that the operator product expansions of all primary operators in the Regge limit have certain universal properties. All of these results are consistent with the expectation that CFTs in this class, irrespective of their microscopic details, admit universal gravity-like holographic dual descriptions. Furthermore, this connection enables us to constrain various inflationary observables such as the amplitude of chiral gravity waves, non-gaussanity of gravity waves and tensor-to-scalar ratio.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2018)·54 citations
28. 28*

    Dual RG flows in 4D

    Steven Abel🇬🇧 · Borut Bajc🇸🇮 · Francesco Sannino🇩🇰

    We present a prescription for using the a central charge to determine the flow of a strongly coupled supersymmetric theory from its weakly coupled dual. The approach is based on the equivalence of the scale-dependent a-parameter derived from the four-dilaton amplitude with the a-parameter determined from the Lagrange multiplier method with scale-dependent R-charges. We explicitly demonstrate this equivalence for massive free N=1 superfields and for weakly coupled SQCD.

    ↳ hep-thhep-phPRD(2019)·0 citations
29. 29*

    Constraints on anharmonic corrections of Fuzzy Dark Matter

    J. A. R. Cembranos🇪🇸 · A. L. Maroto🇪🇸 · S. J. Núñez Jareño🇪🇸 · H. Villarrubia-Rojo🇪🇸

    The cold dark matter (CDM) scenario has proved successful in cosmology. However, we lack a fundamental understanding of its microscopic nature. Moreover, the apparent disagreement between CDM predictions and subgalactic-structure observations has prompted the debate about its behaviour at small scales. These problems could be alleviated if the dark matter is composed of ultralight fields $m\sim 10^{-22}\text{eV}$, usually known as fuzzy dark matter (FDM). Some specific models, with axion-like potentials, have been thoroughly studied and are collectively referred to as ultralight axions (ULAs) or axion-like particles (ALPs). In this work we consider anharmonic corrections to the mass term coming from a repulsive quartic self-interaction. Whenever this anharmonic term dominates, the field behaves as radiation instead of cold matter, modifying the time of matter-radiation equality. Additionally, even for high masses, i.e. masses that reproduce the cold matter behaviour, the presence of anharmonic terms introduce a cut-off in the matter power spectrum through its contribution to the sound speed. We analyze the model and derive constraints using a modified version of CLASS and comparing with CMB and large-scale structure data.

    ↳ astro-ph.COhep-phJHEP(2018)·54 citations
30. 30*

    Blue and violet graviton spectra from a dynamical refractive index

    Massimo Giovannini🇨🇭

    We show that the spectral energy distribution of relic gravitons mildly increases for frequencies smaller than the $\mu$Hz and then flattens out whenever the refractive index of the tensor modes is dynamical during a quasi-de Sitter stage of expansion. For a conventional thermal history the high-frequency plateau ranges between the mHz and the audio band but it is supplemented by a spike in the GHz region if a stiff post-inflationary phase precedes the standard radiation-dominated epoch. Even though the slope is blue at intermediate frequencies, it may become violet in the MHz window. For a variety of post-inflationary histories, including the conventional one, a dynamical index of refraction leads to a potentially detectable spectral energy density in the kHz and in the mHz regions while all the relevant phenomenological constraints are concurrently satisfied.

    ↳ astro-ph.COgr-qchep-phhep-thPLB(2019)·18 citations
31. 31*

    Cosmological constraints with self-interacting sterile neutrinos

    Ningqiang Song🇺🇸 · M.C. Gonzalez-Garcia🇪🇸 · Jordi Salvado🇪🇸

    In this work we revisit the question of whether Cosmology can be made compatible with scenarios with light sterile neutrinos, as invoked to explain the SBL anomalies, in the presence of self-interaction among sterile neutrinos mediated by massive gauge bosons. We examine this proposal by deriving the cosmological predictions of the model in a wide range of the model parameters including the effective interaction strength $G_X$, sterile neutrino mass $m_{\mathrm{st}}$ and active-sterile mixings. With those we perform a statistical analysis of the cosmological data from BBN, CMB, and BAO data to infer the posterior probabilities of the sterile self-interaction model parameters. BBN mostly provides information about the effective interaction strength and we find that ${\log }_{10}(G_X/G_F)\ge 3.6$ can describe the primordial abundances at 95% CL. Our analysis of CMB and BAO data show that when allowing a wide prior for the sterile neutrino mass its posterior is bounded to $m_{\mathrm{st}}\le 0.91\mathrm{eV}$ (95% CL) considering CMB data only and $m_{\mathrm{st}}\le 0.37\mathrm{eV}$ (95% CL) when adding the BAO information. So the mass bounds are slighly relaxed compared with that of a non-interacting sterile neutrino model but a sterile neutrino mass of 1 eV is still excluded at more than $2\sigma$ CL. Conversely if fixing the sterile neutrino mass and mixing to the values prefered by short baseline data we find that while that CMB data alone favors the self-interacting scenario, including the BAO information severly degrades the agreement with the model. Altogether we conclude then that adding the self-interaction can alleviate the tension between eV sterile neutrinos and CMB data, but when including also the BAO results the self-interacting sterile neutrino model cannot lead to a satisfactory description of the data.

    ↳ astro-ph.COhep-phJCAP(2018)·56 citations
32. 32*

    Supercurrent anomaly and gauge invariance in N=1 supersymmetric Yang-Mills theory

    Y. R. Batista🇧🇷 · Brigitte Hiller🇵🇹 · Adriano Cherchiglia🇧🇷 · Marcos Sampaio🇧🇷

    We analyse Feynman diagram calculational issues related to the quantum breaking of supercurrent conservation in a supersymmetric non-abelian Yang-Mills theory. For the sake of simplicity, we take a zero mass gauge field multiplet interacting with a massless Majorana spin-$1/2$ field in the adjoint representation of $SU(2)$. We shed light on a long-standing controversy regarding the perturbative evaluation of the supercurrent anomaly in connection with gauge and superconformal symmetry in different frameworks. We find that only superconformal symmetry is unambiguously broken using an invariant four dimensional regularization and compare with the triangle AVV anomaly. Subtleties related to momentum routing invariance in the loops of diagrams and Clifford algebra evaluation inside divergent integrals are also discussed in connection with finite and undetermined quantities in Feynman amplitudes.

    ↳ hep-thhep-phPRD(2018)·8 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.