Tue·Oct 6, 2020Tuesday·October 6, 2020

1. 01*

   Phenomenology of vector-like leptons with Deep Learning at the Large Hadron Collider

   Felipe F. Freitas🇵🇹 · João Gonçalves🇵🇹 · António P. Morais🇵🇹 · Roman Pasechnik🇸🇪

   In this paper, a model inspired by Grand Unification principles featuring three generations of vector-like fermions, new Higgs doublets and a rich neutrino sector at the low scale is presented. Using the state-of-the-art Deep Learning techniques we perform the first phenomenological analysis of this model focusing on the study of new charged vector-like leptons (VLLs) and their possible signatures at CERN's Large Hadron Collider (LHC). In our numerical analysis we consider signal events for vector-boson fusion and VLL pair production topologies, both involving a final state containing a pair of charged leptons of different flavor and two sterile neutrinos that provide a missing energy. We also consider the case of VLL single production where, in addition to a pair of sterile neutrinos, the final state contains only one charged lepton. All calculated observables are provided as data sets for Deep Learning analysis, where a neural network is constructed, based on results obtained via an evolutive algorithm, whose objective is to maximise either the accuracy metric or the Asimov significance for different masses of the VLL. Taking into account the effect of the three analysed topologies, we have found that the combined significance for the observation of new VLLs at the high-luminosity LHC can range from $5.7\sigma$, for a mass of $1.25\mathrm{TeV}$, all the way up to $28\sigma$ if the VLL mass is $200\mathrm{GeV}$. We have also shown that by the end of the LHC Run-III a $200\mathrm{GeV}$ VLL can be excluded with a confidence of $8.8$ standard deviations. The results obtained show that our model can be probed well before the end of the LHC operations and, in particular, providing important phenomenological information to constrain the energy scale at which new gauge symmetries emergent from the considered Grand Unification picture can be manifest.

   hep-phhep-exJHEP(2021)·34 citations
2. 02*

   Loop-Generated Neutrino Masses in Composite Higgs Models

   Giacomo Cacciapaglia🇫🇷 · Martin Rosenlyst🇩🇰

   We present a composite scotogenic model for neutrino masses, which are generated via loops of ${\mathbb{Z}}_2$-odd composite scalars. We consider three different approaches to the couplings of the neutrinos (including three right-handed singlets) and the composite sector: ETC-like four-fermion interactions, fundamental partial compositeness and fermion partial compositeness. In all cases, the model can feature sizeable couplings and remain viable with respect to various experimental constraints if the three ${\mathbb{Z}}_2$-odd right-handed neutrinos have masses between the TeV and the Planck scales. Additionally, the lightest ${\mathbb{Z}}_2$-odd composite scalar may play the role of Dark Matter, either via thermal freeze-out or as an asymmetric relic. This mechanism can be featured in a variety of models based on vacuum misalignment. For concreteness, we demonstrate it in a composite two-Higgs scheme based on the coset SU(6)/Sp(6).

   hep-phhep-thJHEP(2021)·30 citations
3. 03*

   Second order relativistic viscous hydrodynamics within an effective description of hot QCD medium

   Samapan Bhadury🇮🇳 · Manu Kurian🇮🇳 · Vinod Chandra🇮🇳 · Amaresh Jaiswal🇮🇳

   The second-order hydrodynamic equations for evolution of shear and bulk viscous pressure have been derived within the framework of covariant kinetic theory based on the effective fugacity quasiparticle model. The temperature-dependent fugacity parameter in the equilibrium distribution function leads to a mean field term in the Boltzmann equation which affects the interactions in the hot QCD matter. The viscous corrections to distribution function, up to second-order in gradient expansion, have been obtained by employing a Chapman-Enskog like iterative solution of the effective Boltzmann equation within the relaxation time approximation. The effect of mean field contributions to transport coefficients as well as entropy current has been studied up to second-order in gradients. In contrast to the previous calculations, we find non-vanishing entropy flux at second order. The effective description of relativistic second-order viscous hydrodynamics, for a system of interacting quarks and gluons, has been quantitatively analyzed in the case of the $1+1-$dimensional boost invariant longitudinal expansion. We study the proper time evolution of temperature, pressure anisotropy, and viscous corrections to entropy density for this simplified expansion. The second order evolution of quark-gluon plasma is seen to be affected significantly with the inclusion of mean field contributions and the realistic equation of state.

   hep-phhep-thnucl-thJ.Phys.G(2021)·12 citations
4. 04*

   Observable Proton Decay in Flipped SU(5)

   Maria Mehmood🇵🇰 · Mansoor Ur Rehman🇵🇰 · Qaisar Shafi🇺🇸

   We explore proton decay in a class of realistic supersymmetric flipped $SU(5)$ models supplemented by a $U(1{)}_R$ symmetry which plays an essential role in implementing hybrid inflation. Two distinct neutrino mass models, based on inverse seesaw and type I seesaw, are identified, with the latter arising from the breaking of $U(1{)}_R$ by nonrenormalizable superpotential terms. Depending on the neutrino mass model an appropriate set of intermediate scale color triplets from the Higgs superfields play a key role in proton decay channels that include $p\to (e^{+},{\mu }^{+}){\pi }^0$, $p\to (e^{+},{\mu }^{+})K^0$, $p\to \overline{\nu }{\pi }^{+}$, and $p\to \overline{\nu }{K}^{+}$. We identify regions of the parameter space that yield proton lifetime estimates which are testable at Hyper-Kamiokande and other next generation experiments. We discuss how gauge coupling unification in the presence of intermediate scale particles is realized, and a $Z_4$ symmetry is utilized to show how such intermediate scales can arise in flipped $SU(5)$. Finally, we compare our predictions for proton decay with previous work based on $SU(5)$ and flipped $SU(5)$.

   hep-phJHEP(2021)·22 citations
5. 05*

   ${\rm Y}$ electroproduction at HERA, EIC, and LHeC within the nonrelativistic QCD framework

   Zhan Sun🇨🇳

   Based on the nonrelativistic QCD framework, we study the ${\rm Y}$ production in semi-inclusive deep inelastic electron-proton scattering (SIDIS) at HERA, EIC, and LHeC, with the main aim of assessing the viability of observing ${\rm Y}$ electroproduction at the three colliders. The color-octet (CO) contributions are found to have a crucial effect on both the integrated and differential cross sections, serving to further establish the significance of the CO mechanism. By setting the kinematic cuts to $p_{t,{\rm Y}}^{\star 2}>1{\text{GeV}}^2$, $W>50$ GeV, $2<Q^2<100{\text{GeV}}^2$, and $0.3<z<0.9$, only a few electroproduced ${\rm Y}$ events can be generated at HERA, partially accounting for its lack of measured ${\rm Y}$ electroproduction. However, under the same cut conditions, the EIC and LHeC can accumulate about $8.7\times 10^2$ and $3.7\times 10^4$ reconstructed ${\rm Y}$ events in one operation year, respectively, which manifestly indicates the prospect of detecting the ${\rm Y}$-related SIDIS processes at the two forthcoming $ep(eA)$ colliders.

   hep-phPRD(2020)·1 citation
6. 06*

   Excited lepton triplet contribution to electroweak observables at one loop level

   M. Rehman🇵🇰 · M. E. Gomez🇪🇸 · O. Panella🇮🇹

   In this paper, we present the one-loop radiative corrections to the electroweak precision observable $\Delta \rho$ coming from the $I_W=1$ multiplet excited leptons. We have calculated the couplings of the exotic lepton triplet to the vector bosons and ordinary leptons using effective Lagrangian approach. These couplings are then used to estimate the excited lepton triplet contribution to the $\Delta \rho$ parameter. The mass degenerate excited lepton contribution to $\Delta \rho$ is small and can be neglected. However, if the excited leptons are non-degenerate, their contribution can be large which can result in more stringent constraints on the excited fermion parameter space compared to the constraints from present experimental searches and perturbative unitarity condition.

   hep-phhep-thEPJC(2021)·3 citations
7. 07*

   Lepton angular distribution of $W$ boson productions

   Yang Lyu🇺🇸 · Wen-Chen Chang🇹🇼 · Randall Evan McClellan🇺🇸 · Jen-Chieh Peng🇺🇸 · Oleg Teryaev🇷🇺

   The lepton angular distribution coefficients $A_i$ for $Z$ boson production in $pp$ and $\bar{p}p$ collisions have been measured at the LHC and the Tevatron. A recent study showed that many features of the measured angular distribution coefficients, including the transverse momentum ($q_T$) and rapidity dependencies and the violation of the Lam-Tung relation, can be well described using an intuitive geometric approach. In this paper, we extend this geometric approach to describe the angular distribution coefficients for $W$ boson produced in $\bar{p}p$ collisions at the Tevatron. We first compare the data with a perturbative QCD calculation at $\mathcal{O}({\alpha }_s^2)$. We then show that the data and QCD calculations can be well described with the geometric approach. Implications for future studies at the LHC energy are also discussed.

   hep-phhep-exnucl-exnucl-thPRD(2021)·5 citations
8. 08*

   Combined fit to the cross sections of $e^{+}{e}^{-}\to \pi Z_c(3900)\to \pi \pi J/\psi$ and $e^{+}{e}^{-}\to \pi Z_c(3900)\to \pi D{\bar{D}}^{\ast }$

   Jielei Zhang🇨🇳 · Tengjiao Zhu🇨🇳

   The cross sections of $e^{+}{e}^{-}\to \pi Z_c(3900)\to \pi \pi J/\psi$ and $e^{+}{e}^{-}\to \pi Z_c(3900)\to \pi D{\bar{D}}^{\ast }$ have been measured by BESIII experiment. We try to perform a combined fit to the cross sections with one Breit-Wigner function, the fit results show the structure's mass and width are $M=(4232\pm 5)$ MeV/$c^2$, $\Gamma =(65\pm 21)$ MeV. The ratio $\frac{\mathcal{B}(Z_c(3900)\to D{\bar{D}}^{\ast })}{\mathcal{B}(Z_c(3900)\to \pi J/\psi )}$ is determined to be $(16\pm 6)$. We also try to fit the cross sections with two Breit-Wigner functions, while we can't come to any definitive conclusions about the second structure. More measurements are desired to improve the understanding of $e^{+}{e}^{-}\to \pi Z_c(3900)$ line shape.

   hep-phActa Phys.Polon.B(2020)·0 citations
9. 09*

   Two-loop matching of renormalizable operators: general considerations and applications

   Henning Bahl🇩🇪 · Ivan Sobolev🇩🇪

   Low-energy effective field theories (EFT) encode information about the physics at high energies--i.e., the high-energy theory (HET). To extract this information the EFT and the HET have to be matched to each other. At the one-loop level, general results for the matching of renormalizable operators have already been obtained in the literature. In the present paper, we take a step towards a better understanding of renormalizable operator matching at the two-loop level: Focusing on the diagrammatic method, we discuss in detail the various contributions to two-loop matching conditions and compare different approaches to derive them. Moreover, we discuss which observables are best suited for the derivation of matching conditions. As a concrete application, we calculate the $\mathcal{O}\left({\alpha }_t{\alpha }_s\right)$ and $\mathcal{O}\left({\alpha }_t^2\right)$ matching conditions of the scalar four-point couplings between the Standard Model (SM) and the Two-Higgs-Doublet Model (THDM) as well as the THDM and the Minimal Supersymmetric Standard Model (MSSM). We use the derived formulas to improve the prediction of the SM-like Higgs mass in the MSSM using the THDM as EFT.

   hep-phJHEP(2021)·18 citations
10. 10*

    Resummation of background-collinear corrections in strong field QED

    James P. Edwards🇲🇽 · Anton Ilderton🇬🇧

    Scattering processes in laser backgrounds are degenerate to the emission of unobservable photons collinear with the laser. We identify processes and observables for which such degeneracies factorise and exponentiate, obtaining the leading-order intensity dependence of these inclusive observables at high laser intensity, correct to all orders in the fine-structure constant (all loops, all emissions). The results show an exponential intensity dependence distinct from that predicted by the Narozhny-Ritus conjecture on the high-intensity behaviour of quantum electrodynamics in strong fields.

    hep-phPRD(2021)·25 citations
11. 11*

    Nonlinear photon trident versus double Compton scattering and resummation of one-step terms

    Greger Torgrimsson🇩🇪

    We study the photon trident process, where an initial photon turns into an electron-positron pair and a final photon under a nonlinear interaction with a strong plane-wave background field. We show that this process is very similar to double Compton scattering, where an electron interacts with the background field and emits two photons. We also show how the one-step terms can be obtained by resumming the small- and large-$\chi$ expansions. We consider a couple of different resummation methods, and also propose new resummations (involving Meijer-G functions) which have the correct type of expansions at both small and large $\chi$. These new resummations require relatively few terms to give good precision.

    hep-phhep-thPRD(2020)·16 citations
12. 12*

    Effects of nonstandard interaction on temporal and spatial correlations in neutrino oscillations

    Trisha Sarkar🇮🇳 · Khushboo Dixit🇮🇳

    Effects of physics beyond the standard model in the neutrino sector are conveniently incorporated through non-standard interaction parameters. Assuming new physics in the form of dimension-6 vector operators, a recent global analysis of neutrino oscillation data including results from COHERENT experiment suggests two favorable new physics scenarios. These are LMA-Light (with normal mass ordering) \& LMA-Dark (with inverted mass ordering) sectors of parameters. In this work, we study the effects of new physics solutions on Leggett-Garg-type (LGtI) inequality which quantifies temporal correlations in the system along with flavor entropy and genuine tripartite entanglement which can be considered as measures of spatial correlations. We show that the violation of LGtI for ${\nu }_{\mu }$ energy around 3 GeV in the DUNE experimental set-up can not only be an indication of presence of new physics but such a new physics is expected to be in the form of LMA-Dark sector with inverted ordering. Further, we show that the LMA-Light solution, in general, decreases the values of all measures of quantum correlations in comparison to their SM predictions. On the other hand, the Dark solution can significantly enhance the values of these measures.

    hep-phquant-phEPJC(2021)·13 citations
13. 13*

    Dark matter of any spin -- an effective field theory and applications

    Juan Carlos Criado🇬🇧 · Niko Koivunen🇪🇪 · Martti Raidal🇪🇪 · Hardi Veermäe🇪🇪

    We develop an effective field theory of a generic massive particle of any spin and, as an example, apply this to study higher-spin dark matter (DM). Our formalism does not introduce unphysical degrees of freedom, thus avoiding the potential inconsistencies that may appear in other field-theoretical descriptions of higher spin. Being a useful reformulation of the Weinberg's original idea, the proposed effective field theory allows for consistent computations of physical observables for general-spin particles, although it does not admit a Lagrangian description. As a specific realization, we explore the phenomenology of a general-spin singlet with ${\mathbb{Z}}_2$-symmetric Higgs portal couplings, a setup which automatically arises for high spin, and show that higher spin particles with masses above $O(10)\mathrm{TeV}$ can be viable thermally-produced DM candidates. Most importantly, if the general-spin DM has purely parity-odd couplings, it naturally avoids all DM direct detection bounds, in which case its mass can lie below the electroweak scale. Our formalism reproduces the existing results for low-spin DM, and allows one to develop consistent higher-spin particle physics phenomenology for high- and low-energy experiments and cosmology.

    hep-phhep-thPRD(2020)·32 citations
14. 14*

    Rare charm $\mathbf{c}\to \mathbf{u}\mathbf{\nu }\bar{\mathbf{\nu }}$ dineutrino null tests for ${\mathbf{e}}^{+}{\mathbf{e}}^{-}$-machines

    Rigo Bause🇩🇪 · Hector Gisbert🇩🇪 · Marcel Golz🇩🇪 · Gudrun Hiller🇩🇪

    Rare $|\Delta c|=|\Delta u|=1$ transitions into dineutrinos are strongly GIM-suppressed and constitute excellent null tests of the standard model. While branching ratios of $D\to P\nu \bar{\nu }$, $D\to P^{+}{P}^{-}\nu \bar{\nu }$, $P=\pi ,K$, baryonic ${\Lambda }_c^{+}\to p\nu \bar{\nu }$, and ${\Xi }_c^{+}\to {\Sigma }^{+}\nu \bar{\nu }$ and inclusive $D\to X\nu \bar{\nu }$ decays are experimentally unconstrained, signals of new physics can be just around the corner. We provide model-independent upper limits on branching ratios reaching few $\times 10^{-5}$ in the most general case of arbitrary lepton flavor structure, $\sim 10^{-5}$ for scenarios with charged lepton conservation and few $\times 10^{-6}$ assuming lepton universality. We also give upper limits in $Z^{\prime }$ and leptoquark models. The presence of light right-handed neutrinos can affect these limits, a possibility that can occur for lepton number violation at a TeV, and that can be excluded with an improved bound on $\mathcal{B}(D^0\to \text{invisibles})$ at the level of $\sim 10^{-6}$, about two orders of magnitude better than the present one. Signatures of $c\to u\nu \bar{\nu }$ modes contain missing energy and are suited for experimental searches at $e^{+}{e}^{-}$-facilities, such as BES III, Belle II and future $e^{+}{e}^{-}$-colliders, such as the FCC-ee running at the $Z$.

    hep-phhep-exPRD(2021)·58 citations
15. 15*

    The negative-parity spin-1/2 $\Lambda$ baryon spectrum from lattice QCD and effective theory

    Rafael Pavao🇪🇸 · Philipp Gubler🇯🇵 · Pedro Fernandez-Soler🇪🇸 · Juan Nieves🇪🇸 · Makoto Oka🇯🇵 · Toru T. Takahashi🇯🇵

    The spectrum of the negative-parity spin-1/2 $\Lambda$ baryons is studied using lattice QCD and hadronic effective theory in a unitarized coupled-channel framework. A direct comparison between the two approaches is possible by considering the hadronic effective theory in a finite volume and with hadron masses and mesonic decay constants that correspond to the situation studied on the lattice. Comparing the energy level spectrum and $SU(3)$ flavor decompositions of the individual states, it is found that the lowest two states extracted from lattice QCD can be identified with one of the two $\Lambda (1405)$-poles and the $\Lambda (1670)$ resonance. The quark mass dependences of these two lattice QCD levels are in good agreement with their effective theory counterparts. However, as current lattice QCD studies still rely on three-quark operators to generate the physical states, clear signals corresponding to the meson-baryon scattering states, that appear in the finite volume effective theory calculation, are not yet seen.

    ↳ hep-lathep-phPLB(2021)·12 citations
16. 16*

    Event-shaped-dependent cumulants in p-Pb collisions at 5.02 TeV

    De-Xian Wei🇨🇳 · Li-Juan Zhou🇨🇳

    In this paper, we present a novel event-shaped cumulants (ESC) response approach, based on a multi-phase transport (AMPT) model simulations, to analyze p-Pb collisions at $\sqrt{s_{NN}}$= 5.02 TeV. We find that the Pearson coefficients between the subset cumulants of the final harmonics $v_2\{2k\}(k=1,2,3,4)$ and the subset cumulants of initial eccentricity ${\epsilon }_2\{2k\}$ in the ESC basis are significantly enhanced. These Pearson coefficients are strongly-dependent on the charged multiplicity, the set number of events (SNE), and only weakly-dependent on the order of the multi-particle cumulants (two-particles, four-particles, and so on). Our results show that the ESC method can suppress the event-by-event fluctuations.

    ↳ nucl-thhep-phIJMPE(2022)·1 citation
17. 17*

    Spin Hydrodynamics and Symmetric Energy-Momentum Tensors -- A current induced by the spin vorticity --

    Kenji Fukushima🇯🇵 · Shi Pu🇨🇳

    We discuss a puzzle in relativistic spin hydrodynamics; in the previous formulation the spin source from the antisymmetric part of the canonical energy-momentum tensor (EMT) is crucial. The Belinfante improved EMT is pseudo-gauge transformed from the canonical EMT and is usually a physically sensible choice especially when gauge fields are coupled as in magnetohydrodynamics, but the Belinfante EMT has no antisymmetric part. We find that pseudo-transformed entropy currents are physically inequivalent in nonequilibrium situations. We also identify a current induced by the spin vorticity read from the Belinfante symmetric EMT.

    ↳ hep-thhep-phPLB(2021)·167 citations
18. 18*

    Few-neutron systems with the long-range Casimir-Polder force

    R. Higa🇧🇷 · J. F. Babb🇺🇸

    In this work we present results of the long-range electromagnetic Casimir-Polder interactions between two neutrons, a neutron and a conducting wall, and a neutron between two walls. As input, we use the dynamic dipole polarizabilities of the neutron fitted to chiral EFT results up to the pion production threshold and at the onset of the Delta resonance. Our work can be relevant to the physics of confined ultracold neutrons inside bottles.

    ↳ nucl-thhep-phphysics.atom-phBraz.J.Phys.(2021)·1 citation
19. 19*

    Robust laboratory limits on a cosmological spatial gradient in the electromagnetic fine-structure constant from accelerometer experiments

    Yevgeny V. Stadnik🇯🇵

    Quasar absorption spectral data indicate the presence of a spatial gradient in the electromagnetic fine-structure constant $\alpha$ on cosmological length scales. We point out that experiments with accelerometers, including torsion pendula and atom interferometers, can be used as sensitive probes of cosmological spatial gradients in the fundamental constants of nature, which give rise to equivalence-principle-violating forces on test masses. Using laboratory data from the Eöt-Wash experiment, we constrain spatial gradients in $\alpha$ along any direction to be $|\nabla \alpha /\alpha |<6.6\times 10^{-4}(\text{Glyr}{)}^{-1}$ at $95\%$ confidence level. Our result represents an order of magnitude improvement over laboratory bounds from clock-based searches for a spatial gradient in $\alpha$ directed along the observed cosmological $\alpha$-dipole axis. Improvements to accelerometer experiments in the foreseeable future are expected to provide sufficient sensitivity to test the cosmological $\alpha$-dipole seen in astrophysical data.

    ↳ physics.atom-phastro-ph.COgr-qchep-ph+1PRA(2021)·3 citations
20. 20*

    Data Augmentation at the LHC through Analysis-specific Fast Simulation with Deep Learning

    Cheng Chen🇨🇳 · Olmo Cerri🇺🇸 · Thong Q. Nguyen🇺🇸 · Jean-Roch Vlimant🇺🇸 · Maurizio Pierini🇨🇭

    We present a fast simulation application based on a Deep Neural Network, designed to create large analysis-specific datasets. Taking as an example the generation of W+jet events produced in sqrt(s)= 13 TeV proton-proton collisions, we train a neural network to model detector resolution effects as a transfer function acting on an analysis-specific set of relevant features, computed at generation level, i.e., in absence of detector effects. Based on this model, we propose a novel fast-simulation workflow that starts from a large amount of generator-level events to deliver large analysis-specific samples. The adoption of this approach would result in about an order-of-magnitude reduction in computing and storage requirements for the collision simulation workflow. This strategy could help the high energy physics community to face the computing challenges of the future High-Luminosity LHC.

    ↳ physics.comp-phcs.LGhep-exhep-ph12 citations
21. 21*

    Color Screening in Quantum Chromodynamics

    Alexei Bazavov🇺🇸 · Johannes Heinrich Weber🇺🇸

    We review lattice studies of the color screening in the quark-gluon plasma. We put the phenomena related to the color screening into the context of similar aspects of other physical systems (electromagnetic plasma or cold nuclear matter). We discuss the onset of the color screening and its signature and significance in the QCD transition region, and elucidate at which temperature and to which extent the weak-coupling picture based on hard thermal loop expansion, potential nonrelativistic QCD, or dimensionally-reduced QCD quantitatively captures the key properties of the color screening. We discuss the different regimes pertaining to the color screening and thermal dissociation of the static quarks in depth for various spatial correlation functions that are studied on the lattice, and clarify the status of their asymptotic screening masses. We finally discuss the screening correlation functions of dynamical mesons with a wide range of flavor and spin content, and how they conform with expectations for low- and high-temperature behavior.

    ↳ hep-lathep-phPPNP(2021)·32 citations
22. 22*

    Low-energy constant $L_{10}$ in a two-representation lattice theory

    Maarten Golterman🇺🇸 · William I. Jay🇺🇸 · Ethan T. Neil🇺🇸 · Yigal Shamir🇮🇱 · Benjamin Svetitsky🇮🇱

    We calculate the low-energy constant $L_{10}$ in a two-representation SU(4) lattice gauge theory that is close to a composite-Higgs model. From this we obtain the contribution of the new strong sector to the $S$ parameter. This leads to an upper bound on the vacuum misalignment parameter $\xi$ which is similar to current estimates of this bound. Our result agrees with large-$N_c$ scaling expectations, within large systematic uncertainties.

    ↳ hep-lathep-phPRD(2021)·10 citations
23. 23*

    Non linear quantum electrodynamics, longitudinal photon state and cosmological distances

    Damian Ejlli🇬🇧

    In this work, I study the non-linear QED effects to the Maxwell equations due to the interaction of the electromagnetic waves with an external magnetic field with arbitrary direction with respect to the direction of propagation of the electromagnetic waves. I show that in the case when the external magnetic field has a longitudinal component with respect to the electromagnetic wave direction of propagation, a longitudinal photon state is generated in a magnetized vacuum. The mixing of transverse and longitudinal photon states causes a decrease in the group velocity with respect to the velocity of electromagnetic waves in a vacuum. In a cosmological context, as far as a cosmic magnetic field is concerned, the decrease of the group velocity of any form of electromagnetic radiation would cause changes in several distance measures in cosmology. The most affected of these distance measures turn out to be the comoving distance and the luminosity distance. The absolute change in distance measures are usually large but the relative changes are very small.

    ↳ hep-thastro-ph.COgr-qchep-ph0 citations
24. 24*

    Testing Stochastic Gravitational Wave Signals from Primordial Black Holes with Optical Telescopes

    Sunao Sugiyama🇯🇵 · Volodymyr Takhistov🇺🇸 · Edoardo Vitagliano🇺🇸 · Alexander Kusenko🇺🇸 · Misao Sasaki🇯🇵 · Masahiro Takada🇯🇵

    Primordial black holes (PBHs) can constitute the predominant fraction of dark matter (DM) if PBHs reside in the currently unconstrained "sublunar" mass range. PBHs originating from scalar perturbations generated during inflation can naturally appear with a broad spectrum in a class of models. The resulting stochastic gravitational wave (GW) background generated from such PBH production can account for the recently reported North American Nanohertz Observatory for Gravitational Waves (NANOGrav) pulsar timing array data signal, and will be testable in future GW observations by interferometer-type experiments such as Laser Interferometer Space Antenna (LISA). We show that the broad mass function of such PBH DM is already being probed by Subaru Hyper Suprime-Cam (HSC) microlensing data and is consistent with a detected candidate event. Upcoming observations of HSC will be able to provide an independent definitive test of the stochastic GW signals originating from such PBH DM production scenarios.

    ↳ astro-ph.COastro-ph.GAhep-phPLB(2021)·82 citations
25. 25*

    MCNNTUNES: tuning Shower Monte Carlo generators with machine learning

    Marco Lazzarin🇮🇹 · Simone Alioli🇮🇹 · Stefano Carrazza🇮🇹

    The parameters tuning of event generators is a research topic characterized by complex choices: the generator response to parameter variations is difficult to obtain on a theoretical basis, and numerical methods are hardly tractable due to the long computational times required by generators. Event generator tuning has been tackled by parametrisation-based techniques, with the most successful one being a polynomial parametrisation. In this work, an implementation of tuning procedures based on artificial neural networks is proposed. The implementation was tested with closure testing and experimental measurements from the ATLAS experiment at the Large Hadron Collider.

    ↳ physics.comp-phhep-exhep-phComput.Phys.Commun.(2021)·14 citations
26. 26*

    Witten effect, anomaly inflow, and charge teleportation

    Hajime Fukuda🇺🇸 · Kazuya Yonekura🇯🇵

    We study a phenomenon that electric charges are "teleported" between two spatially separated objects without exchanging charged particles at all. For example, this phenomenon happens between a magnetic monopole and an axion string in four dimensions, two vortices in three dimensions, and two M5-branes in M-theory in which M2-charges are teleported. This is realized by anomaly inflow into these objects in the presence of cubic Chern-Simons terms. In particular, the Witten effect on magnetic monopoles can be understood as a general consequence of anomaly inflow, which implies that some anomalous quantum mechanics must live on them. Charge violation occurs in the anomalous theories living on these objects, but it happens in such a way that the total charge is conserved between the two spatially separated objects. We derive a formula for the amount of the charge which is teleported between the two objects in terms of the linking number of their world volumes in spacetime.

    ↳ hep-thcond-mat.str-elhep-phJHEP(2021)·19 citations
27. 27*

    Spurious Poles in the Scattering of Electric and Magnetic Charges

    John Terning🇺🇸 · Christopher B. Verhaaren🇺🇸

    Theories with both electric and magnetic charges ("mutually non-local" theories) have several major obstacles to calculating scattering amplitudes. Even when the interaction arises through the kinetic mixing of two, otherwise independent, U(1)'s, so that all low-energy interactions are perturbative, difficulties remain: using a self-dual, local formalism leads to spurious poles at any finite order in perturbation theory. Correct calculations must show how the spurious poles cancel in observable scattering amplitudes. Consistency requires that one type of charge is confined as a result of one of the U(1)'s being broken. Here we show how the constraints of confinement and parity conservation on observable processes manages to cancel the spurious poles in scattering and pair production amplitudes, paving the way for systematic studies of the experimental signatures of "dark" electric-magnetic processes. Along the way we demonstrate some novel effects in electric-magnetic interactions, including that the amplitude for single photon production of magnetic particles by electric particles vanishes.

    ↳ hep-thhep-phJHEP(2020)·23 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.