Mon·Aug 19, 2019Monday·August 19, 2019

1. 01*

   Signatures of Dipolar Dark Matter on Indirect Detection

   C. Arellano-Celiz🇲🇽 · A. Avilez-López🇲🇽 · J. E. Barradas-Guevara🇲🇽 · A. Carrillo-Monteverde🇲🇽 · J. L. Díaz-Cruz🇲🇽 · O. Félix-Beltrán🇲🇽

   In this work we study the annihilation of fermionic dark matter, considering it as a neutral particle with non-vanishing magnetic ($M$) and electric ($D$) dipole moments. Effective cross section of the process $\chi \overline{\chi }\to \gamma \gamma$ is computed starting from a general form of the coupling $\chi \overline{\chi }\gamma$ in the framework of an extension of the Standard Model. By taking into account the annihilation of dark matter pairs into mono-energetic photons, we found that for masses of $O(10^2)$ GeV, an electric dipole moment $\sim 10^{-16}\text{e cm}$ is required to satisfy the current relic density inferences. Additionally, in order to pin down models viable to describe the physics of dark matter in the early Universe, we also constrain our model according to recent measurements of the temperature anisotropies of the cosmic microwave background radiation, and report constraints to the electric and magnetic dipole moments for a range of masses within our model.

   hep-phJ.Phys.G(2023)·4 citations
2. 02*

   Threshold Effects in Heavy Quarkonium Spectroscopy and Decays

   J. Ferretti🇺🇸

   The possible importance of threshold effects in heavy quarkonium spectroscopy is discussed. The starting point is the calculation of the spectrum of heavy quarkonium-like states with self-energy/threshold corrections. Two different approaches are compared: I) The Unquenched Quark Model (UQM); II) A novel coupled-channel model, based on the UQM formalism. The latter provides a possible solution to the long-standing problem of convergence in UQM calculations; it also makes it possible to distinguish between states which are almost pure quarkonia and exotic states, characterized by non-negligible threshold (or continuum) components in their wave functions. The UQM-based coupled-channel model is used to study the ${\chi }_{\mathrm{c}}(2P)$ and ${\chi }_{\mathrm{b}}(3P)$ multiplets: ${\chi }_{\mathrm{c}}(2P)$'s are described as charmonium-like states with non-negligible molecular-type components in their wave functions, ${\chi }_{\mathrm{b}}(3P)$'s as almost pure bottomonia. Other possible applications of the UQM and the UQM-based coupled-channel model formalisms to the calculation of other observables, like the strong decay amplitudes, are also discussed.

   hep-phAIP Conf.Proc.(2020)·0 citations
3. 03*

   Deep inelastic scattering from string/gauge duality with soft IR cutoff and exponentially small Bjorken parameter

   Eduardo Folco Capossoli🇧🇷 · Henrique Boschi-Filho🇧🇷

   In this work we use the string/gauge duality within the Softwall Model (SW). In this model a dilaton field is introduced in the action for the fields playing the role of a soft infrared (IR) cutoff. The SW model is very useful as it provides linear Regge trajectories for mesons. Here, using a $10-$dimensional SW model, we calculate the corresponding structure functions for deep inelastic scattering (DIS) in which electrons are scattered off hadrons in a kinematical regime where the hadrons are broken apart, with high virtuality $q$, in the exponentially small $x$ (Bjorken parameter) regime. Our results for this regime are consistent with those achieved using other holographic and non-holographic approaches.

   hep-phhep-thJ.Phys.Conf.Ser.(2019)·0 citations
4. 04*

   Linearly polarised Transverse Momentum Dependent Parton Distribution Function at NNLO in QCD

   Daniel Gutierrez-Reyes🇪🇸 · Sergio Leal Gómez🇪🇸 · Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇩🇪

   We present for first time the computation at large $q_T$ (or small $b_T$) matching coefficients of Transverse Momentum Dependent Parton Distribution Function (TMDPDF) for linearly polarised to the integrated gluon distribution at next-to-next-to leading order (NNLO). The computation is performed using the modified $\delta$-regulator for rapidity divergences and dimensional regularization. This TMDPDF matriz element presnts phenomenological interest in two kind of processes. The factorization of the Higgs production transverse momentum ($q_T$) distribution through gluon-gluon fusion and the quarkonium production.

   hep-phPoS(2019)·0 citations
5. 05*

   Effects of fluctuations and color-neutrality in a finite volume

   Christian Spieles🇩🇪 · Marcus Bleicher🇩🇪 · Carsten Greiner🇩🇪

   We investigate properties of strongly interacting matter in a schematic model, based on the combined degrees of freedom of a non-interacting hadronic phase and a non-interacting deconfined phase. It is found that in a finite system both phases contribute to the thermodynamic state due to fluctuations and that signatures of critical behviour like the divergence of statistical quantities are damped. The constraint of color-neutrality leads to a volume-dependent shift of the effective critical temperature, which follows a scaling law, independent of the baryochemical potential. According to the model, observable baryon-number susceptibilities at a given $T$ and ${\mu }_B$ strongly depend on the system size. Finally, we compare hadronization conditions from the model with hadrochemical fits to experimental collider data, where a qualitatively similar system size dependence is extracted.

   hep-phAstron.Nachr.(2019)·3 citations
6. 06*

   Polyakov linear-sigma model in mean-field approximation and optimized perturbation theory

   Abdel Nasser Tawfik (Nile U., ECTP and Johann Wolfgang Goethe-Universitat)🇪🇬 · Carsten Greiner (Johann Wolfgang Goethe-Universitat)🇩🇪 · Abdel Magied Diab (Egyptian Ctr. Theor. Phys., Cairo and WLCAPP, Cairo)🇪🇬 · M.T. Ghoneim🇪🇬 · H. Anwer (Cairo U.)🇪🇬

   We compare results from the Polyakov linear-sigma model (PLSM) in optimized perturbation theory (OPT) with the mean-field approximation (MFA). At finite temperatures and chemical potentials, the chiral condensates and the decofinement order parameters, the thermodynamic pressure, the pseudo-critical temperatures, the subtracted condensates, the second- and high-order moments of various conserved charges (cumulants) obtained in MFA are compared with OPT and also confronted to available lattice QCD simulations. We conclude that when moving from lower- to higher-order moments of various quantum charges, OPT becomes more closer to QCD.

   hep-phhep-thPRC(2020)·10 citations
7. 07*

   Nonlinear QED in an ultrastrong rotating electric field: Signatures of the momentum-dependent effective mass

   Erez Raicher🇩🇪 · Karen Z. Hatsagortsyan🇩🇪

   The specific features of nonlinear pair production and radiation processes in an ultratsrong rotating electric field are investigated, taking into account that this field models the antinodes of counterpropagating laser beams. It is shown that a particle in a rotating electric field acquires an effective mass which depends on its momentum absolute value as well as on its direction with respect to the field plane. This phenomenon has an impact on the nonlinear Breit-Wheeler and nonlinear Compton processes. The spectra of the produced pairs in the first case, and the emitted photon in the second case, are shown to bear signatures of the effective mass. In the first case, the threshold for pair production by a $\gamma$-photon in the presence of this field varies according to the photon propagation direction. In the second case, varying the energy of the incoming electron allows for the measurement of the momentum dependence of the effective mass. Two corresponding experimental setups are suggested.

   hep-phphysics.plasm-phPRResearch(2020)·6 citations
8. 08*

   Cosmological Relaxation of Higgs Mass Before and After LHC and Naturalness

   Gia Dvali🇩🇪

   In post LHC era the old idea of cosmological vacuum relaxation of the Higgs mass that does not require any new physics in the vicinity of LHC energies acquires a new meaning. I discuss how this concept of naturanless differs from the standard one by 't Hooft. Here the observed value of the Higgs mass corresponds to a vacuum of infinite degeneracy and infinite entropy. Therefore, it represents and attractor point of cosmic inflationary evolution. This information is unavailable for a low energy observer living in one of such vacua. By not seeing any stabilizing physics at LHC such an observer is puzzled and creates an artificial problem of naturalness which in reality does not exist. We explain why this solution is fully compatible with the concept of Wilsonian decoupling.

   hep-phgr-qchep-th17 citations
9. 09*

   Neutrino, Electroweak and Nuclear Physics from COHERENT Elastic Neutrino-Nucleus Scattering with a New Quenching Factor

   M. Cadeddu🇮🇹 · F. Dordei🇮🇹 · C. Giunti🇮🇹 · Y.F. Li🇨🇳 · Y.Y. Zhang🇨🇳

   We present an updated analysis of the coherent neutrino-nucleus elastic scattering data of the COHERENT experiment taking into account the new quenching factor published recently in Phys. Rev. D100, 033003 (2019). Through a fit of the COHERENT time-integrated energy spectrum, we show that the new quenching factor leads to a better determination of the average rms radius of the neutron distributions of ${}^{133}\text{Cs}$ and ${}^{127}\text{I}$, while in combination with the atomic parity violation (APV) experimental results it allows to determine a data-driven APV measurement of the low-energy weak mixing angle in very good agreement with the Standard Model prediction. We also find a $3.7\sigma$ evidence of the suppression of coherence due to the nuclear structure. Neutrino properties are better constrained by considering the COHERENT time-dependent spectral data, that allow us to improve the bounds on the neutrino charge radii and magnetic moments. We also present for the first time constraints on the neutrino charges obtained with coherent neutrino-nucleus elastic scattering data. In particular, we obtain the first laboratory constraints on the diagonal charge of ${\nu }_{\mu }$ and the ${\nu }_{\mu }$-${\nu }_{\tau }$ transition charge.

   hep-phhep-exPRD(2020)·75 citations
10. 10*

    Angular momentum of the electron: One-loop studies

    Bogdan Damski🇵🇱

    We combine bare perturbation theory with the imaginary time evolution technique to study one-loop radiative corrections to various components of angular momentum of the electron. Our investigations are based on the canonical decomposition of angular momentum, where spin and orbital components, associated with fermionic and electromagnetic degrees of freedom, are individually approached. We use for this purpose quantum electrodynamics in the general covariant gauge and develop a formalism, based on the repeated use of the Sochocki-Plemelj formula, for proper enforcement of the imaginary time limit. It is then shown that careful implementation of imaginary time evolutions is crucial for getting a correct result for total angular momentum of the electron in the bare perturbative expansion. We also analyze applicability of the Pauli-Villars regularization to our problem, developing a variant of this technique based on modifications of studied observables by subtraction of their ghost operator counterparts. It is then shown that such an approach leads to the consistent regularization of all angular momenta that we compute.

    hep-phhep-thquant-phNPB(2020)·2 citations
11. 11*

    Electromagnetic angular momentum of the electron: One-loop studies

    Bogdan Damski🇵🇱

    We study angular momentum of the electron stored in its electric and magnetic fields. We use for this purpose quantum electrodynamics in the covariant gauge. We show that a finite one-loop result for such angular momentum can be obtained without invoking any renormalization procedure. We compare it to the classical estimation relying on a short-distance cutoff.

    hep-phhep-thquant-phNPB(2019)·3 citations
12. 12*

    A Practical and Consistent Parametrization of Dark Matter Self-Interactions

    Xiaoyong Chu🇦🇹 · Camilo Garcia-Cely🇩🇪 · Hitoshi Murayama🇺🇸

    Self-interacting dark matter has been proposed to explain the apparent mass deficit in astrophysical small-scale halos, while observations from galaxy clusters suggest that the corresponding cross section depends on the velocity. Accounting for this is often believed to be highly model-dependent with studies mostly focusing on scenarios with light mediators. Based on the effective-range formalism, in this work we point out a model-independent approach which accurately approximates the velocity dependence of the self-interaction cross section with only two parameters. We illustrate how this parameterization can be simultaneously interpreted in various well-motivated scenarios, including self-interactions induced by Yukawa forces, Breit-Wigner resonances and bound states. We investigate the astrophysical implications and discuss how the approximation can be improved in certain special regimes where it works poorly.

    hep-phastro-ph.HEJCAP(2020)·52 citations
13. 13*

    QCD Axion on Hilltop by a Phase Shift of $\pi$

    Fuminobu Takahashi🇯🇵 · Wen Yin🇰🇷

    We show that the initial misalignment angle of the QCD axion (or axion-like particles) can be set very close to $\pi$, if the QCD axion has a mixing with another heavy axion which induces the phase shift $\approx \pi$ after inflation. In the simplest case, the heavy axion plays the role of the inflaton, and we call such inflation as "$\pi$nflation." The basic idea was first proposed by Daido and the present authors in Ref. [1702.03284] in 2017 and more recently discussed in Ref. [1903.00462]. We show that the QCD axion with a decay constant $f_a\gtrsim 3\times 10^9$ GeV can explain dark matter by the $\pi$nflation mechanism. A large fraction of the parameter region has an overlap with the projected sensitivity of ORGAN, MADMAX, TOORAD and IAXO. We also study implications for the effective neutrino species and isocurvature perturbations. The $\pi$nflation can provide an initial condition for the hilltop inflation in the axion landscape, and in a certain set-up, a chain of the hilltop inflation may take place.

    hep-phastro-ph.COgr-qchep-exJHEP(2019)·85 citations
14. 14*

    Gravitational waves, CMB polarization, and the Hubble tension

    Donghui Jeong🇺🇸 · Marc Kamionkowski🇺🇸

    The discrepancy between the Hubble parameter inferred from local measurements and that from the cosmic microwave background (CMB) has motivated careful scrutiny of the assumptions that enter both analyses. Here we point out that the location of the recombination peak in the CMB B-mode power spectrum is determined by the light horizon at the surface of last scatter and thus provides an alternative early-Universe standard ruler. It can thus be used as a cross-check for the standard ruler inferred from the acoustic peaks in the CMB temperature power spectrum and to test various explanations for the Hubble tension. The measurement can potentially be carried out with a precision of $\lesssim 2\%$ with stage-IV B-mode experiments. The measurement can also be used to measure the propagation speed of gravitational waves in the early Universe.

    ↳ astro-ph.COgr-qchep-phPRL(2020)·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.