Tue·Jul 24, 2018Tuesday·July 24, 2018

1. 01*

   Radiative neutrino mass via fermion kinetic mixing

   Sin Kyu Kang🇰🇷 · Oleg Popov🇰🇷

   We propose that the radiative generation of the neutrino mass can be achieved by incorporating the kinetic mixing of fermion fields which arises radiatively at one-loop level. As a demonstrative example of the application of the mechanism, we present the particular case of the Standard Model extension by $U(1{)}_D$ symmetry. As a result, we show how neutrino masses can be generated via a kinetic mixing portal instead of a mass matrix with residual symmetries responsible for the stability of multicomponent dark matter.

   hep-phPRD(2018)·12 citations
2. 02*

   Sterile Neutrinos in String Derived Models

   Alon E. Faraggi🇬🇧

   The MiniBooNE collaboration recently reported further evidence for the existence of sterile neutrinos, implying substantial mixing with the left-handed active neutrinos and at a comparable mass scale. I argue that while sterile neutrinos may arise naturally in large volume string models, they prove more of a challenge in heterotic-string models that replicate the Grand Unified Theory structure of the Standard Model matter states. Sterile neutrinos in heterotic-string models may imply the existence of an additional Abelian gauge symmetry of order 10-100TeV.

   hep-phhep-thEPJC(2018)·9 citations
3. 03*

   Loop-induced Neutrino Non-Standard Interactions

   Ingolf Bischer🇩🇪 · Werner Rodejohann🇩🇪 · Xun-Jie Xu🇩🇪

   Non-Standard Interactions (NSI) of neutrinos may originate from models in which new particles interact with neutrinos. In scalar extensions of the SM, the typical approach to obtain NSI requires Fierz transformations and charged Higgses, which suffer from strong constraints from collider searches or charged lepton flavor violation processes. We propose here an alternative approach to generate NSI, namely via loop processes. We show that such loop-induced NSI from secret neutrino interactions can reach sizes of $\mathcal{O}(0.1\sim 1)$ compared to standard Fermi interaction. This approach can also give rise to neutrino-quark NSI.

   hep-phhep-exJHEP(2018)·29 citations
4. 04*

   Confinement Horizon and QCD Entropy

   Paolo Castorina🇮🇹 · Alfredo Iorio🇨🇿

   Within the picture of quark confinement as due to a \textit{color event horizon}, and of hadronization as an instance of the Unruh radiation for the strong force, we show here that QCD entropy, evaluated by lattice simulations in the region $T_c<T<1.3T_c$, is in reasonable agreement with a melting color event horizon.

   hep-phgr-qchep-thInt.J.Mod.Phys.A(2018)·6 citations
5. 05*

   Extrapolation for meson screening masses from imaginary to real chemical potential

   Masahiro Ishii🇯🇵 · Akihisa Miyahara🇯🇵 · Hiroaki Kouno🇯🇵 · Masanobu Yahiro🇯🇵

   We first extend our formulation for the calculation of $\pi$- and $\sigma$-meson screening masses to the case of finite chemical potential $\mu$. We then consider the imaginary-$\mu$ approach, which is an extrapolation method from imaginary chemical potential ($\mu =i{\mu }_{\mathrm{I}}$) to real one ($\mu ={\mu }_{\mathrm{R}}$). The feasibility of the method is discussed based on the entanglement Polyakov-loop extended Nambu--Jona-Lasinio (EPNJL) model in 2-flavor system. As an example, we investigate how reliable the imaginary-$\mu$ approach is for $\pi$- and $\sigma$-meson screening masses, comparing "screening masses at ${\mu }_{\mathrm{R}}$ in the method" with "those calculated directly at ${\mu }_{\mathrm{R}}$". We finally propose the new extrapolation method and confirm its efficiency.

   hep-phhep-latnucl-thPRD(2019)·2 citations
6. 06*

   Non-standard signatures of vector-like quarks in a leptophobic 221 model

   Kasinath Das🇮🇳 · Tanmoy Mondal🇮🇳 · Santosh Kumar Rai🇮🇳

   We consider vector-like quarks in a leptophobic 221 model characterized by the gauge group $SU(2{)}_L\times SU(2{)}_2\times U(1{)}_X$, where the $SU(2{)}_2$ is leptophobic in nature. We discuss about the pattern of mixing between Standard Model quarks and vector-like quarks and how we prevent tree level flavour-changing interactions in the model. The model also predicts tauphilic scalars decaying mostly to tau leptons. We consider a typical signal of the model in the form of pair production of top-type vector-like quarks which decays to the tauphilic scalars and a third generation quark. We analyze the resulting final state signal for the 13 TeV LHC, containing $\ge 3j(1b)+\ge 2\tau +\ge 1l$ and discuss the discovery prospects of such vector-like quarks with non-standard decay modes.

   hep-phPRD(2019)·13 citations
7. 07*

   Charged scalars confronting neutrino mass and muon g-2 anomaly

   Nabarun Chakrabarty🇹🇼 · Cheng-Wei Chiang🇹🇼 · Takahiro Ohata🇯🇵 · Koji Tsumura🇯🇵

   The present work introduces two possible extensions of the Standard Model Higgs sector. In the first case, the Zee-Babu type model for the generation of neutrino mass is augmented with a scalar triplet and additional singly charged scalar singlets. The second scenario, on the other hand, generalizes the Type-II seesaw model by replicating the number of the scalar triplets. A ${\mathbb{Z}}_3$ symmetry is imposed in case of both the scenarios, but, allowed to be violated by terms of mass dimension two and three for generating neutrino masses and mixings. We examine how the models so introduced can explain the experimental observation on the muon anomalous magnetic moment. We estimate the two-loop contribution to neutrino mass induced by the scalar triplet, in addition to what comes from the doubly charged singlet in the usual Zee-Babu framework, in the first model. On the other hand, the neutrino mass arises in the usual Type-II fashion in the second model. In addition, the role of the ${\mathbb{Z}}_3$ symmetry in suppressing lepton flavor violation is also elucidated.

   hep-phJHEP(2018)·20 citations
8. 08*

   Revisiting Flavor and CP Violation in Supersymmetric SU(5) with Right-Handed Neutrinos

   Jason L. Evans🇰🇷 · Kenji Kadota🇰🇷 · Takumi Kuwahara🇰🇷

   We revisit the minimal supersymmetric SU(5) grand unified theory with three right-handed neutrinos in which universality conditions for soft-supersymmetry breaking parameters are imposed at an input scale above the unification scale. If the Majorana masses for the neutrinos are around $10^{15}$ GeV, large mixing angles and phases in the neutrino sector lead to flavor-violation and CP-violation in the right-handed down squark and left-handed slepton sectors. Since the observed Higgs boson mass and the proton decay constraints indicate sfermions have masses larger than a few TeV, flavor and CP constraints are less restrictive. We explore the constraints on models with a universal soft-supersymmetry breaking input parameters coming from proton stability, electric dipole moments, $\mu \to e\gamma$ decays, and the Higgs mass observed at the LHC. Regions compatible with all constraints can be found if non-zero A-terms are taken.

   hep-phPRD(2018)·9 citations
9. 09*

   Weak quasielastic hyperon production leading to pions in the antineutrino-nucleus reactions

   A. Fatima🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳

   In this review, we have studied the quasielastic production cross sections and polarization components of $\Lambda$, ${\Sigma }^0$ and ${\Sigma }^{-}$ hyperons induced by the weak charged currents in the antineutrino reactions on the nucleon and the nuclear targets like ${}^{12}$C, ${}^{16}$O, ${}^{40}$Ar and ${}^{208}$Pb. It is shown that the energy and the $Q^2$ dependence of the cross sections and the various polarization components can be effectively used to determine the axial vector transition form factors in the strangeness sector and test the validity of various symmetry properties of the weak hadronic currents like G-invariance, T-invariance and SU(3) symmetry. In particular, the energy and the $Q^2$ dependence of the polarization components of the hyperons is found to be sensitive enough to determine the presence of the second class current with or without T-invariance. These hyperons decay dominantly into pions giving an additional contribution to the weak pion production induced by the antineutrinos. This contribution is shown to be quantitatively significant as compared to the pion production by the $\Delta$ excitation in the nuclear targets in the sub-GeV energy region relevant for the ${\bar{\nu }}_{\mu }$ cross section measurements in the oscillation experiments. We have also included a few new results, based on our earlier works, which are in the kinematic region of the present and future (anti)neutrino experiments being done with the accelerator (anti)neutrinos at T2K, MicroBooNE, MiniBooNE, NO$\nu$A, MINER$\nu$A and DUNE, as well as for the atmospheric (anti)neutrino experiments in this energy region.

   hep-phnucl-thFront.in Phys.(2019)·18 citations
10. 10*

    Quarkonium tomography of heavy ion collisions at the LHC

    Ivan Vitev🇺🇸

    Quarkonium production in high-energy hadronic collisions provides a fundamental test of QCD. Its modification in a nuclear medium is a sensitive probe of the space-time temperature profile and transport properties of the QGP, yielding constraints complementary to the ones obtained from the quenching of light hadrons and jets, and open heavy flavor. In these proceedings, we report new results for the suppression of high transverse momentum charmonium [$J/\psi ,\psi (2S)$] and bottomonium [${\rm Y}(1S),{\rm Y}(2S),{\rm Y}(3S)$] states in Pb+Pb collisions at the Large Hadron Collider. Our theoretical formalism combines the collisional dissociation of quarkonia, as they propagate in the quark-gluon plasma, with the thermal wavefunction effects due to the screening of the $Q\bar{Q}$ attractive potential in the medium. We find that a good description of the relative suppression of the ground and higher excited quarkonium states, transverse momentum and centrality distributions is achieved, when comparison to measurements at a center-of-mass energy of 2.76 TeV is performed. Theoretical predictions for the highest Pb+Pb center-of-mass energy of 5.02 TeV at the LHC, where new experimental results are being finalized are presented. Preliminary calculations for smaller systems, such as Xe+Xe are also shown. Last but not least, the potential of jet substructure to shed light in the mechanisms of heavy flavor production is discussed.

    hep-phnucl-thNPA(2019)·1 citation
11. 11*

    Coulomb corrections to the bremsstrahlung and electron pair production cross section of high-energy muons on extended nuclei

    Alexander Sandrock🇩🇪 · Wolfgang Rhode🇩🇪

    The energy reconstruction of high-energy muons depends on the energy loss characteristics. Accurate knowledge of the cross sections of the energy loss processes is necessary for precise measurements of the energy spectrum of muons and muon-induced neutrinos. The cross sections of the two most dominant processes, electron pair production and bremsstrahlung are calculated exact in the coupling parameter $Z\alpha$ to the electromagnetic field of a nucleus for realistic extended screened nuclei. An analytical parametrization of the mass and nuclear-charge dependence of the cross section is given.

    hep-ph8 citations
12. 12*

    Mass Spectra and Decay Constants of Heavy-Light Mesons: A Case Study of QCD Sum Rules and Quark Model

    Halil Mutuk🇹🇷

    In this paper we visited mass spectra and decay constants of pseudoscalar and vector heavy-light mesons ($B$, $B_s$, $D$ and $D_S$) in the framework of QCD sum rule and quark model. The harmonic oscillator wave function was used in quark model while a simple interpolating current was used in QCD sum rule calculation. We obtained good results in accordance with the available experimental data and theoretical studies.

    hep-phAdv.High Energy Phys.(2018)·24 citations
13. 13*

    Analysis of the vector and axialvector $QQ\bar{Q}\bar{Q}$ tetraquark states with QCD sum rules

    Zhi-Gang Wang🇨🇳 · Zun-Yan Di🇨🇳

    In this article, we construct the axialvector-diquark-axialvector-antidiquark type currents to study both the vector and axialvector $QQ\bar{Q}\bar{Q}$ tetraquark states with the QCD sum rules, and obtain the masses $M_{Y(cc\bar{c}\bar{c},1^{+-})}=6.05\pm 0.08\mathrm{GeV}$, $M_{Y(cc\bar{c}\bar{c},1^{--})}=6.11\pm 0.08\mathrm{GeV}$, $M_{Y(bb\bar{b}\bar{b},1^{+-})}=18.84\pm 0.09\mathrm{GeV}$, $M_{Y(bb\bar{b}\bar{b},1^{--})}=18.89\pm 0.09\mathrm{GeV}$. The vector tetraquark states lie $40\mathrm{MeV}$ above the corresponding centroids of the $0^{++}$, $1^{+-}$ and $2^{++}$ tetraquark states, which is a typical feature of the vector tetraquark states consist of four heavy quarks.

    hep-phActa Phys.Polon.B(2019)·92 citations
14. 14*

    $R_{D^{(\ast )}}$, $R_{K^{(\ast )}}$ and neutrino mass in the 2HDM-III with right-handed neutrinos

    Shao-Ping Li🇨🇳 · Xin-Qiang Li🇨🇳 · Ya-Dong Yang🇨🇳 · Xin Zhang🇨🇳

    Given that the two-Higgs-doublet model of type III (2HDM-III) has the potential to address the $R_{D^{(\ast )}}$ anomalies while the resolution to the $R_{K^{(\ast )}}$ deficits requires new degrees of freedom within this framework, we consider in this paper a unified scenario where the low-scale type-I seesaw mechanism is embedded into the 2HDM-III, so as to accommodate the $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies as well as the neutrino mass. We first revisit the $R_{D^{(\ast )}}$ anomalies and find that the current world-averaged results can be addressed at $2\sigma$ level without violating the bound from the branching ratio $\mathcal{B}(B_c^{-}\to {\tau }^{-}\bar{\nu })⩽30\%$. The scenario predicts two sub-eV neutrino masses based on a decoupled heavy Majorana neutrino and two nearly degenerate Majorana neutrinos with mass around the electroweak scale. For the $R_{K^{(\ast )}}$ anomalies, the same scenario can generate the required Wilson coefficients in the direction $C_{9\mu }^{\mathrm{NP}}=-C_{10\mu }^{\mathrm{NP}}<0$, with $\mathcal{O}(1)$ Yukawa couplings for the muon and the top quark.

    hep-phhep-exJHEP(2018)·57 citations
15. 15*

    Highest Energy Proton-Nucleus Cross Sections

    Leo Stodolsky🇩🇪

    The description of very high energy proton-proton cross sections in terms of a `black disc' with an `edge' allows of a simple generalization to highest energy proton-nucleus cross sections. This results in a leading $l{n}^{2}W$ term and a $lnW$ term whose coefficient depends linearly on the radius of the nucleus ($W$ the c.m. energy). The necessary parameters are determined from the fits to p-p data. Since the coefficient of the $lnW$ term is rather large, it is doubtful that the regime of $l{n}^{2}W$ dominance can be reached with available energies in accelerators or cosmic rays. However, the $lnW$ term can be relevant for highest energy cosmic rays in the atmosphere, where a large increase for the cross section on nitrogen is expected. Tests of the theory should be possible by studying the coefficient of $lnW$ at p-nucleus colliders.

    hep-phastro-ph.HEhep-exMod.Phys.Lett.A(2019)·1 citation
16. 16*

    Testable Axion-Like Particles In The Minimal Linear {\sigma} Model

    Javier Alonso-Gonzalez🇪🇸 · Luca Merlo🇪🇸 · Federico Pobbe🇮🇹 · Stefano Rigolin🇮🇹 · Olcyr Sumensari🇮🇹

    Axion and axion-like particle models are typically affected by a strong fine-tuning problem in conceiving the electroweak and the Peccei-Quinn breaking scales. Within the context of the Minimal Linear {\sigma} Model, axion-like particle constructions are identified where this hierarchy problem is solved, accounting for a TeV Peccei-Quinn breaking scale and a pseudoscalar particle with a mass larger than 10 MeV. Potential signatures at colliders and B-factories are discussed.

    hep-phNPB(2020)·19 citations
17. 17*

    Theory of CP violation in B decays

    K. Keri Vos🇩🇪

    The study of CP violation in $B$-meson decays has already reached a high level of precision, which will be pushed even higher in the future era of Belle-II and the LHCb upgrade. %Important probes of CP violation are the $B_d^0$ and $B_s^0$ mixing phases and the CKM angle $\gamma$. Here, the theoretical challenge is to control the uncertainties from strong interactions to distinguish between the Standard Model and possible New Physics effects. In this talk, I will present a selected overview of recent theoretical developments in this field. This includes, in particular, the semileptonic asymmetry $a_{\text{sl}}^s$ and extractions of the CKM angle $\gamma$ and the $B_d^0$ and $B_s^0$ mixing phases. I focus on recently proposed strategies in which the theory uncertainties can be controlled through data using flavour symmetries of the strong interaction. A newly found puzzle in the $B\to \pi K$ system is highlighted and a theoretically clean way to determine the underlying electroweak penguin parameters is discussed. Finally, the recent progress to describe three-body $B$ decays in QCD factorization is discussed.

    hep-phPoS(2018)·0 citations
18. 18*

    Probing the Weizsäcker-Williams gluon Wigner distribution in pp collisions

    Renaud Boussarie🇵🇱 · Yoshitaka Hatta🇯🇵 · Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸

    We show that the diffractive forward production of two quarkonia, especially the ${\chi }_{cJ}$ and ${\eta }_c$ states, in proton-proton or proton-ion collisions can access the Weizsäcker-Williams gluon Wigner distribution of the proton. We use the hybrid factorization approach where the collinear, double gluon PDF is applied for one of the protons and the $k_T$-dependent (Wigner or GTMD) distribution for the other. The production of quarkonia is treated in the NRQCD framework. A particularly concise formula is obtained for double ${\chi }_{J=1}$ production.

    hep-phPRD(2018)·53 citations
19. 19*

    TASI Lectures on Early Universe Cosmology: Inflation, Baryogenesis and Dark Matter

    James M. Cline🇨🇦

    These lectures, presented at TASI 2018, provide a concise introduction to inflation, baryogenesis, and aspects of dark matter not covered by the other lectures. The emphasis for inflation is an intuitive understanding and techniques for constraining inflationary models. For baryogenesis we focus on two examples, leptogenesis and electroweak baryogenesis, with attention to singlet-assisted two-step phase transitions. Concerning dark matter, we review different classes of models distinguished by their mechanisms for obtaining the observed relic density, including thermal freeze-out, asymmetric dark matter, freeze-in, SIMP dark matter, the misalignment mechanism for ultralight scalars and axions, and production of primordial black holes during inflation. Problem sets are provided.

    hep-phastro-ph.COPoS(2019)·66 citations
20. 20*

    Machine Learning Uncertainties with Adversarial Neural Networks

    Christoph Englert🇬🇧 · Peter Galler🇬🇧 · Philip Harris🇺🇸 · Michael Spannowsky🇬🇧

    Machine Learning is a powerful tool to reveal and exploit correlations in a multi-dimensional parameter space. Making predictions from such correlations is a highly non-trivial task, in particular when the details of the underlying dynamics of a theoretical model are not fully understood. Using adversarial networks, we include a priori known sources of systematic and theoretical uncertainties during the training. This paves the way to a more reliable event classification on an event-by-event basis, as well as novel approaches to perform parameter fits of particle physics data. We demonstrate the benefits of the method explicitly in an example considering effective field theory extensions of Higgs boson production in association with jets.

    hep-phhep-exEPJC(2019)·84 citations
21. 21*

    Influence of backreaction of electric fields and Schwinger effect on inflationary magnetogenesis

    O.O. Sobol🇨🇭 · E.V. Gorbar🇺🇦 · M. Kamarpour🇺🇦 · S.I. Vilchinskii🇺🇦

    We study the generation of electromagnetic fields during inflation when the conformal invariance of Maxwell's action is broken by the kinetic coupling $f^2(\varphi )F_{\mu \nu }{F}^{\mu \nu }$ of the electromagnetic field to the inflaton field $\varphi$. We consider the case where the coupling function $f(\varphi )$ decreases in time during inflation and, as a result, the electric component of the energy density dominates over the magnetic one. The system of equations which governs the joint evolution of the scale factor, inflaton field, and electric energy density is derived. The backreaction occurs when the electric energy density becomes as large as the product of the slow-roll parameter $ϵ$ and inflaton energy density, ${\rho }_E\sim ϵ{\rho }_{\inf }$. It affects the inflaton field evolution and leads to the scale-invariant electric power spectrum and the magnetic one which is blue with the spectral index $n_B=2$ for any decreasing coupling function. This gives an upper limit on the present-day value of observed magnetic fields below $10^{-22}\mathrm{G}$. It is worth emphasizing that since the effective electric charge of particles $e_{\mathrm{eff}}=e/f$ is suppressed by the coupling function, the Schwinger effect becomes important only at the late stages of inflation when the inflaton field is close to the minimum of its potential. The Schwinger effect abruptly decreases the value of the electric field, helping to finish the inflation stage and enter the stage of preheating. It effectively produces the charged particles, implementing the Schwinger reheating scenario even before the fast oscillations of the inflaton. The numerical analysis is carried out in the Starobinsky model of inflation for the powerlike $f\propto a^{\alpha }$ and Ratra-type $f=\exp (\beta \varphi /M_p)$ coupling functions.

    hep-phastro-ph.COgr-qcPRD(2018)·57 citations
22. 22*

    Deep Inelastic Scattering on an Extremal RN-AdS Black Hole

    Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸

    We consider deep inelastic scattering (DIS) on a large nucleus described as an extremal RN-AdS black hole using the holographic principle. Using the R-current correlators we determine the structure functions as a function Bjorken-x, and map it on a finite but large nucleus with fixed atomic number. The R-ratio of the nuclear structure functions exhibit strong shadowing at low-x.

    ↳ hep-thhep-phnucl-thPRD(2020)·5 citations
23. 23*

    Two novel approaches to the hadron-quark mixed phase in compact stars

    Vahagn Abgaryan🇷🇺 · David Alvarez-Castillo🇷🇺 · Alexander Ayriyan🇷🇺 · David Blaschke🇵🇱 · Hovik Grigorian🇷🇺

    First-order phase transitions, like the liquid-gas transition, proceed via formation of structures such as bubbles and droplets. In strongly interacting compact star matter, at the crust-core transition, but also at the hadron-quark transition in the core, these structures form different shapes dubbed "pasta phases". We describe two methods to obtain one-parameter families of hybrid equations of state (EoS) which mimic the thermodynamic behavior of pasta phases in between a low-density hadron and a high-density quark matter phase, thus generalizing the Maxwell construction. The first method replaces the behavior of pressure vs. chemical potential in a finite region around the critical %chemical potential pressure of the Maxwell construction by a polynomial interpolation. The second method uses extrapolations of the hadronic and quark matter EoS beyond the Maxwell point to define a mixing of both with weight functions bounded by finite limits around the Maxwell point. We apply both methods to the case of a hybrid EoS with a strong first order transition that entails the formation of a third family of compact stars and the corresponding mass twin phenomenon. We investigate for both models the robustness of this phenomenon against variation of the single parameter, the pressure increment at the critical chemical potential which quantifies the deviation from the Maxwell construction. We also show sets of results for other compact star observables than mass and radius, namely the moment of inertia and the baryon mass.

    ↳ astro-ph.HEhep-phnucl-thUniverse(2018)·37 citations
24. 24*

    The $\pi \gamma \to \pi \pi$ transition and the $\rho$ radiative decay width from lattice QCD

    Constantia Alexandrou🇨🇾 · Luka Leskovec🇺🇸 · Stefan Meinel🇺🇸 · John Negele🇺🇸 · Srijit Paul🇨🇾 · Marcus Petschlies🇩🇪 · Andrew Pochinsky🇺🇸 · Gumaro Rendon🇺🇸 · Sergey Syritsyn🇺🇸

    We report a lattice QCD determination of the $\pi \gamma \to \pi \pi$ transition amplitude for the $P$-wave, $I=1$ two-pion final state, as a function of the photon virtuality and $\pi \pi$ invariant mass. The calculation was performed with $2+1$ flavors of clover fermions at a pion mass of approximately $320$ MeV, on a $32^3\times 96$ lattice with $L\approx 3.6$ fm. We construct the necessary correlation functions using a combination of smeared forward, sequential and stochastic propagators, and determine the finite-volume matrix elements for all $\pi \pi$ momenta up to $|\vec{P}|=\sqrt{3}\frac{2\pi }{L}$ and all associated irreducible representations. In the mapping of the finite-volume to infinite-volume matrix elements using the Lellouch-Lüscher factor, we consider two different parametrizations of the $\pi \pi$ scattering phase shift. We fit the $q^2$ and $s$ dependence of the infinite-volume transition amplitude in a model-independent way using series expansions, and compare multiple different truncations of this series. Through analytic continuation to the $\rho$ resonance pole, we also determine the $\pi \gamma \to \rho$ resonant transition form factor and the $\rho$ meson photocoupling, and obtain $|G_{\rho \pi \gamma }|=0.0802(32)(20)$.

    ↳ hep-lathep-phnucl-thPRD(2018)·83 citations
25. 25*

    Nonperturbative investigations of SU(3) gauge theory with eight dynamical flavors

    Lattice Strong Dynamics (LSD) Collaboration: Thomas Appelquist🇺🇸 · Richard C. Brower🇺🇸 · George T. Fleming🇺🇸 · Andrew Gasbarro🇺🇸 · Anna Hasenfratz🇺🇸 · Xiao-Yong Jin🇺🇸 · Ethan T. Neil🇺🇸 · James C. Osborn🇺🇸 · Claudio Rebbi🇺🇸 · Enrico Rinaldi🇺🇸 · David Schaich🇨🇭 · Pavlos Vranas🇺🇸 · Evan Weinberg🇺🇸 · Oliver Witzel🇺🇸

    We present our lattice studies of SU(3) gauge theory with $N_f$ = 8 degenerate fermions in the fundamental representation. Using nHYP-smeared staggered fermions we study finite-temperature transitions on lattice volumes as large as $L^3\times N_t=48^3\times 24$, and the zero-temperature composite spectrum on lattice volumes up to $64^3\times 128$. The spectrum indirectly indicates spontaneous chiral symmetry breaking, but finite-temperature transitions with fixed $N_t\le 24$ enter a strongly coupled lattice phase as the fermion mass decreases, which prevents a direct confirmation of spontaneous chiral symmetry breaking in the chiral limit. In addition to the connected spectrum we focus on the lightest flavor-singlet scalar particle. We find it to be degenerate with the pseudo-Goldstone states down to the lightest masses reached so far by non-perturbative lattice calculations. Using the same lattice approach, we study the behavior of the composite spectrum when the number of light fermions is changed from eight to four. A heavy flavor-singlet scalar in the 4-flavor theory affirms the contrast between QCD-like dynamics and the low-energy behavior of the 8-flavor theory.

    ↳ hep-lathep-phPRD(2019)·130 citations
26. 26*

    Nonlinear chiral transport from holography

    Yanyan Bu🇨🇳 · Tuna Demircik🇮🇱 · Michael Lublinsky🇮🇱

    Nonlinear transport phenomena induced by the chiral anomaly are explored within a 4D field theory defined holographically as $U(1{)}_V\times U(1{)}_A$ Maxwell-Chern-Simons theory in Schwarzschild-$Ad{S}_5$. First, in presence of external electromagnetic fields, a general form of vector and axial currents is derived. Then, within the gradient expansion up to third order, we analytically compute all (over 50) transport coefficients. A wealth of higher order (nonlinear) transport phenomena induced by chiral anomaly are found beyond the Chiral Magnetic and Chiral Separation Effects. Some of the higher order terms are relaxation time corrections to the lowest order nonlinear effects. The charge diffusion constant and dispersion relation of the Chiral Magnetic Wave are found to receive anomaly-induced non-linear corrections due to e/m background fields. Furthermore, there emerges a new gapless mode, which we refer to as {\it Chiral Hall Density Wave}, propagating along the background Poynting vector.

    ↳ hep-thhep-phnucl-thJHEP(2019)·17 citations
27. 27*

    Kinematics of Spiral galaxies as a Portal to the Nature of Dark Matter

    Paolo Salucci🇮🇹

    The gravitational field of Spiral galaxies is well traced by their rotation curves. Only recently it has become of extreme interest that the latter form a family ruled by two parameters of the {\it luminous} component: the disk length-scale $R_D$ and the magnitude $M_I$. This evidence is so strong and consequential that it must be taken as the starting point for the investigation on the issue of the dark matter in galaxies. The emerging fact is that structural quantities deeply rooted in the luminous components, like the disk length scales are found to tightly correlate with structural quantities deeply rooted in the dark component, like the DM halo core radii. This unexpected evidence may strongly call for a shift of paradigm with respect to the current Cold collisionless Dark Matter one.

    ↳ astro-ph.GAastro-ph.COhep-ph1 citation
28. 28*

    Astrophysical explanations of suspected dark matter signals in dwarf galaxies

    Alex Geringer-Sameth🇬🇧 · Savvas M. Koushiappas🇺🇸 · Matthew G. Walker🇺🇸 · Vincent Bonnivard🇫🇷 · Céline Combet🇫🇷 · David Maurin🇫🇷

    We present methods to assess whether gamma-ray excesses towards Milky Way dwarf galaxies can be attributed to astrophysical sources rather than to dark matter annihilation. As a case study we focus on Reticulum II, the dwarf which shows the strongest evidence for a gamma-ray signal in Fermi data. Dark matter models and those with curved energy spectra provide good fits to the data, while a simple power law is ruled out at 97.5% confidence. We compare RetII's spectrum to known classes of gamma-ray sources and find a useful representation in terms of spectral curvature and the energy at which the spectral energy distribution peaks. In this space the blazar classes appear segregated from the confidence region occupied by RetII. Pulsars have similar gamma-ray spectra to RetII but we show that RetII is unlikely to host a pulsar population detectable in gamma rays. Tensions with astrophysical explanations are stronger when analyzing 6.5 years of Pass 7 than with the same amount of Pass 8 data, where the excess is less significant. These methods are applicable to any dwarf galaxy which is a promising dark matter target and shows signs of gamma-ray emission along its line of sight.

    ↳ astro-ph.HEastro-ph.GAhep-ph7 citations
29. 29*

    Boundary Surface Term In QCD Is At Finite Distance Due To Confinement of Quarks and Gluons Inside Finite Size Hadron

    Gouranga C Nayak🇺🇸

    In this paper we show that since we have not observed quarks and gluons outside the hadron due to the confinement of quarks and gluons inside the hadron, the boundary surface term in QCD is at the finite distance which is at the surface of the finite size hadron. Since the boundary surface is at the finite distance we find that the boundary surface term in QCD is non-zero irrespective of the form of the $r$ dependence of the gluon field ${\hat{A}}_{\mu }^a(t,r)$ and the $r$ dependence of the quark field ${\hat{\psi }}_i(t,r)$ where $a=1,...,8$ and $i=1,2,3$ are the color indices. We show that this is consistent with the fact that the cluster decomposition property fails in QCD due to confinement.

    ↳ physics.gen-phhep-ph10 citations
30. 30*

    Composite Nambu--Jona-Lasinio inflation near infrared fixed point of the Horava-Lifshitz theory

    Daris Samart (Chulalongkorn U.)🇹🇭 · Phongpichit Channuie (Walailak U.)🇹🇭

    In this work, we first propose a cosmological scenario inherently based on the effective Nambu--Jona-Lasio (NJL) model near the infrared (IR) limit of the Hořava-Lifshitz (HL) theory. Having used the one-loop correction, we employ the NJL framework in the ultraviolet (UV) limit of the HL theory, with critical exponent $z=3$, to demonstrate in the IR limit that the symmetry of the potential at the critical coupling value is broken at $z=1$. We also derive the effective Higgs-like potential in the low energy regimes. Here the symmetry of the effective potential will be broken near $z=1$ at a certain value of the critical coupling. In our scenario, the scalar channel of the NJL model plays the role of a composite inflaton. We find that the Lorentz invariance (LI) appears at the IR regime of the HL theory and employ the standard inflationary (slow-roll) paradigm as a probe of physics at very high energy. We compute inflationary parameters and compare them with recent Planck 2015 data. Interestingly, we discover that the predictions of the model are in perfect agreement with the Planck analysis. Our salient feature is that we used inflation to quantify the IR and UV fixed points of the underlying theory. We discover that the IR fixed point of HL gravity is compatible with the grand unified energy scale; whilst the UV fixed point is the Planck energy scale.

    ↳ hep-thgr-qchep-phPLB(2019)·2 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.