Thu·Feb 13, 2020Thursday·February 13, 2020

1. 01*

   Resonance Searches with Machine Learned Likelihood Ratios

   Jacob Hollingsworth🇺🇸 · Daniel Whiteson🇺🇸

   We demonstrate the power of machine-learned likelihood ratios for resonance searches in a benchmark model featuring a heavy Z' boson. The likelihood ratio is expressed as a function of multivariate detector level observables, but rather than being calculated explicitly as in matrix-element-based approaches, it is learned from a joint likelihood ratio which depends on latent information from simulated samples. We show that bounds drawn using the machine learned likelihood ratio are tighter than those drawn using a likelihood ratio calculated from histograms.

   hep-ph22 citations
2. 02*

   Chiral Anomaly, Dirac Sea and Berry monopole in Wigner Function Approach

   Ren-Hong Fang🇨🇳 · Jian-Hua Gao🇨🇳

   Within Wigner function formalism, the chiral anomaly arises naturally from the Dirac sea contribution in un-normal-ordered Wigner function. For massless fermions, the Dirac sea contribution behaves like a 4-dimensional or 3-dimensional Berry monopole in Euclidian momentum space, while for massive fermions, although Dirac sea still leads to the chiral anomaly but there is no Berry monopole at infrared momentum region. We discuss these points explicitly in a simple and concrete example.

   hep-phNPA(2021)·2 citations
3. 03*

   MUonE sensitivity to new physics explanations of the muon anomalous magnetic moment

   P. S. Bhupal Dev🇺🇸 · Werner Rodejohann🇩🇪 · Xun-Jie Xu🇩🇪 · Yongchao Zhang🇺🇸

   The MUonE experiment aims at a precision measurement of the hadronic vacuum polarization contribution to the muon $g-2$, via elastic muon-electron scattering. Since the current muon $g-2$ anomaly hints at the potential existence of new physics (NP) related to the muon, the question then arises as to whether the measurement of hadronic vacuum polarization in MUonE could be affected by the same NP as well. In this work, we address this question by investigating a variety of NP explanations of the muon $g-2$ anomaly via either vector or scalar mediators with either flavor-universal, non-universal or even flavor-violating couplings to electrons and muons. We derive the corresponding MUonE sensitivity in each case and find that the measurement of hadronic vacuum polarization at the MUonE is not vulnerable to any of these NP scenarios.

   hep-phhep-exJHEP(2020)·60 citations
4. 04*

   Fundamental Composite Dynamics: A Review

   Giacomo Cacciapaglia🇫🇷 · Claudio Pica🇩🇰 · Francesco Sannino🇩🇰

   We introduce fundamental gauge theories that can be employed to construct informed composite bright and dark extensions of the Standard Model, within and beyond the standard paradigms. The gap between theory and experiments is bridged by providing predictions and ways to test them, for example, at the Fermi scale and via precision flavor experiments. We will review time-honoured paradigms from (walking) technicolor to composite Goldstone Higgs and discuss their features and differences. Standard model fermion mass generation in composite models will also be discussed along with the challenges and opportunities that it offers. To be concrete and pedagogical we will concentrate on minimal constructions featuring strongly coupled gauge theories supporting the global symmetry breaking pattern SU(4)/Sp(4). The most minimal underlying fundamental description consists of an SU(2) gauge theory with two Dirac fermions transforming according to the fundamental representation of the gauge group. This minimal choice enables us to use first principle lattice results to predict the massive spectrum for models of composite (Goldstone) Higgs dynamics and strongly interacting dark matter, of immediate impact for current and future experimental searches. Because composite dynamics embraces a rich spectrum of theories with dynamics ranging from QCD-like behaviour to (near) conformal one, we also report here the state-of-the-art of numerical and analytic properties of several strongly coupled theories including their spectrum, phase diagrams and, when applicable, their (near) conformal data.

   hep-phhep-exhep-lathep-thPhys.Rept.(2020)·201 citations
5. 05*

   HQ Collisional energy loss in a magnetized medium

   Balbeer Singh🇮🇳 · Surasree Mazumder🇮🇳 · Hiranmaya Mishra🇮🇳

   We study the effect of the magnetic field on the collisional energy loss of heavy quark (HQ) moving in a magnetized thermal partonic medium. This is investigated in the strong field approximation where the lowest Landau level (LLL) becomes relevant. We work in the limit $g\sqrt{eB}\ll T\ll \sqrt{eB}$ which is relevant for heavy ion collisions. Effects of the magnetic field are incorporated through the resummed gluon propagator in which the dominant contribution arises from the quark loop. We also take the approximation $\sqrt{eB}\ll M$, M being the HQ mass, so that the HQ is not Landau quantized. It turns out that there are only two types of scatterings that contribute to the energy loss of HQ; the Coulomb scattering of HQ with light quarks/anti-quarks and the t-channel Compton scattering. It is observed that for a given magnetic field, the dominant contribution to the collisional energy loss arises from Compton scattering process i.e., $Qg\to Qg$. On the other hand, of the two processes, the Coulomb scattering i.e., $Qq\to Qq$ is more sensitive to the magnetic field. The net collisional energy loss is seen to increase with increase in the magnetic field. For a reasonable strength of the magnetic field, the field dependent contribution to the collisional energy loss is of the same order as to the case without magnetic field which can be important for the jet quenching phenomena in the heavy ion collision experiments.

   hep-phJHEP(2020)·20 citations
6. 06*

   Natural Top-Bottom Mass Hierarchy in Composite Higgs Models

   Martin Rosenlyst🇩🇰 · Christopher T. Hill🇺🇸

   We consider composite two-Higgs doublet models based on gauge-Yukawa theories with strongly interacting fermions generating the top-bottom mass hierarchy. The model features a single "universal" Higgs-Yukawa coupling, $g$, which is identified with the top quark $g\equiv g_t\sim \mathcal{O}(1)$. The top-bottom mass hierarchy arises by soft breaking of a ${\mathbb{Z}}_2$ symmetry by a condensate of strongly interacting fermions. A mass splitting between vector-like masses of the confined techni-fermions controls this top-bottom mass hierarchy. This mechanism can be present in a variety of models based on vacuum misalignment. For concreteness, we demonstrate it in a composite two-Higgs scheme.

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

   Quarkonium production and suppression: Theory

   Alexander Rothkopf🇳🇴

   Heavy quarkonium theory has seen significant progress over the past years. Not only has the community steadily improved the understanding of fully equilibrated quarkonium using first principles lattice QCD studies, but it has taken major steps towards developing a genuine dynamical understanding of quark-antiquark pairs immersed in a hot medium by embracing the paradigm of open quantum systems. We review recent developments, placing an emphasis on quarkonium real-time dynamics.

   hep-phNPA(2021)·5 citations
8. 08*

   Multipole Photon Radiation in the Vincia Parton Shower

   Peter Skands🇦🇺 · Rob Verheyen🇬🇧

   We present algorithms that interleave photon radiation from the final state and the initial state with the QCD evolution in the antenna-based Vincia parton shower. One of the algorithms incorporates the complete soft and collinear structure associated with photon emission, but may be computationally expensive, while the other approximates the soft structure at a lower cost. Radiation from fermions and W bosons is included, and a strategy for photon radiation off leptons below the hadronization scale is set up. We show results of the application of the shower algorithms to Drell-Yan and WW production at the LHC, showing the impact of the inclusion of the full soft structure and treatment of radiation off W bosons.

   hep-phPLB(2020)·18 citations
9. 09*

   Search for boosted dark matter with high-Z material in underground experiments

   Xin Chen🇨🇳 · Litao Yang🇨🇳

   We propose to search for a boosted dark matter (DM) particle from astrophysical sources using an emulsion detector in deep underground facilities. We further propose using high-$Z$ material such as the lead for a larger DM-nucleus coherent scattering cross section above a threshold. The boosted DM will scatter into an excited DM. While the nuclear recoil energy is not detected, the decay products from the excited DM can be recorded by the proposed detector. Backgrounds such as the high energy solar neutrinos can be controlled by the reconstructed track topology. The proposed detector has the potential to find a boosted DM in the sub-GeV mass region, and in certain parameter space, an observation can be made while there is no sensitivity in other large-volume detectors such as Super-K.

   hep-ph2 citations
10. 10*

    On plasmon contribution to the hot A_0 condensate

    O. A. Borisenko🇺🇦 · V. V. Skalozub🇺🇦

    In SU(2) gluodynamics, the Debye gluon contribution W_D(A_0) to the effective action of the temporal gauge field component, A_0 = const, at high temperature is calculated in the background R^{xi} gauge. It is shown that at nonzero A_0 the standard definition k_0 = 0, |k| -> 0 corresponds to long distance correlations for the longitudinal in internal space gluons. The transversal gluons become screened by the A_0 background field. Therefore they give zero contributions and have to be excluded from the correlation corrections. The total effective action accounting for the one-loop, two-loop and correct W_D(A_0) satisfies Nielsen's identity that proves gauge invariance of the A_0 condensation phenomenon.

    hep-ph3 citations
11. 11*

    Isolating the Odderon in central production in high energy $pA$ and $AA$ collisions

    R. McNulty🇮🇪 · V.A. Khoze🇬🇧 · A.D. Martin🇬🇧 · M.G. Ryskin🇬🇧

    We study the rapidity dependence of the cross section on the rapidity of the central exclusive production cross sections of C-even mesons in $pA$ and $AA$ collisions, where $A$ is a heavy ion. We observe qualitatively different behaviour of the contributions arising from $\gamma$-Odderon and Pomeron-Pomeron fusion mechanisms. This can be used to extract the Odderon signal from the events of $f_2$ mesons exclusively produced in the forward region. Estimates, obtained using expected values of the Odderon cross section, indicate that the $\gamma$-Odderon contribution may exceed by a few times the Pomeron-induced background in Pb-Pb collisions. Moreover, the Odderon effect can be clearly seen in terms of the asymmetry in $pA$ and $AA$ collisions with the beam and target reversed. It is particularly interesting to note that the asymmetry for $\gamma$-Odderon fusion reaches its maximum value close to 1 in the forward direction, whereas the asymmetry for the Pomeron-Pomeron fusion contribution is small. The role of additional interactions of the $f_2$ meson with nucleons in the heavy ion, and also the contributions from secondary Reggeons, are estimated. The photon-Odderon contribution has a large normalisation uncertainty but the enhances cross-section in the forward region combined with a large asymmetry increases the chance of experimentally detecting the Odderon.

    hep-phEPJC(2020)·6 citations
12. 12*

    Induced color charges, effective gamma-gamma-gluon vertex in QGP. Applications to heavy-ion collisions

    V. Skalozub🇺🇦

    We calculate the induced color charges Q_{ind.}^3, Q_{ind.}^8 and the effective vertex gamma - gamma - gluon generated in quark-gluon plasma with the A_0 condensate because of the color parity violation at this background. To imitate the case of heavy-ion collisions, we consider the model of the plasma confined in the narrow infinite plate and derive the classical gluon potentials Phi^3, Phi^8 produced by these charges. Two applications - scattering of photons on the plasma and conversion of gluon fields in two photons radiated from the plasma - are discussed.

    hep-phUkr.J.Phys.(2019)·2 citations
13. 13*

    Electromagnetic field of ultrarelativistic charge in topologically random nuclear matter

    Kirill Tuchin🇺🇸

    Electromagnetic field of a fast electric charge in nuclear matter with spatially uniform but random topological charge density is derived. A useful approximation is developed for the relativistic heavy-ion collisions.

    hep-phnucl-thNPA(2020)·5 citations
14. 14*

    Multiplicity Dependence of Shear Viscosity, Isothermal Compressibility and Speed of Sound in $pp$ collisions at $\sqrt{s}$ = 7 TeV

    Dushmanta Sahu🇮🇳 · Sushanta Tripathy🇮🇳 · Raghunath Sahoo🇮🇳 · Archita Rani Dash🇮🇳

    In order to understand the detailed dynamics of systems produced in $pp$ collisions, it is essential to know about the Equation of State (EoS) and various thermodynamic properties. In this work, we study the shear viscosity to entropy density ratio, isothermal compressibility and speed of sound of the system by considering a differential freeze-out scenario. We have used a thermodynamically consistent Tsallis non-extensive statistics to have a better explanation for the dynamics of $pp$ collision systems. While the shear viscosity to entropy density ratio provides information about the measure of fluidity of a system formed in high energy collisions, the isothermal compressibility gives a clear idea about the deviation of the system from a perfect fluid. The speed of sound in the system as a function of $⟨d{N}_{\mathrm{ch}}/d\eta ⟩$ gives us a vivid picture of the dynamics of the system. The results show quite an intuitive perspective on high multiplicity $pp$ collisions and give us a limit of $⟨d{N}_{\mathrm{ch}}/d\eta ⟩$ $\gtrsim$ (10 - 20), after which a change in the dynamics of the system may be observed.

    hep-phhep-exnucl-exnucl-thEPJA(2020)·19 citations
15. 15*

    Precise determination of proton magnetic radius from electron scattering data

    J. M. Alarcón🇪🇸 · D. W. Higinbotham🇺🇸 · C. Weiss🇺🇸

    We extract the proton magnetic radius from the high-precision electron-proton elastic scattering cross section data. Our theoretical framework combines dispersion analysis and chiral effective field theory and implements the dynamics governing the shape of the low-$Q^2$ form factors. It allows us to use data up to $Q^2\sim$ 0.5 GeV${}^2$ for constraining the radii and overcomes the difficulties of empirical fits and $Q^2\to 0$ extrapolation. We obtain a magnetic radius $r_M^p$ = 0.850 $\pm$0.001 (fit 68%) $\pm$0.010 (theory full range) fm, significantly different from earlier results obtained from the same data, and close to the extracted electric radius $r_E^p$ = 0.842 $\pm$0.002 (fit) $\pm$0.010 (theory) fm.

    hep-phhep-latnucl-exnucl-th+1PRC(2020)·42 citations
16. 16*

    WIMP Cogenesis for Asymmetric Dark Matter and the Baryon Asymmetry

    Yanou Cui🇺🇸 · Michael Shamma🇺🇸

    We propose a new mechanism where asymmetric dark matter (ADM) and the baryon asymmetry are both generated in the same decay chain of a metastable weakly interacting massive particle (WIMP) after its thermal freeze-out. Dark matter and baryons are connected by a generalized baryon number that is conserved, while the DM asymmetry and baryon asymmetry compensate each other. This unified framework addresses the DM-baryon coincidence while inheriting the merit of the conventional WIMP miracle in predicting relic abundances of matter. Examples of renormalizable models realizing this scenario are presented. These models generically predict ADM with sub-GeV to GeV-scale mass that interacts with Standard Model quarks or leptons, thus rendering potential signatures at direct detection experiments sensitive to low mass DM. Other interesting phenomenological predictions are also discussed, including: LHC signatures of new intermediate particles with color or electroweak charge and DM induced nucleon decay; the long-lived WIMP may be within reach of future high energy collider experiments.

    hep-phastro-ph.COhep-exhep-thJHEP(2020)·22 citations
17. 17*

    High-Temperature Electroweak Symmetry Non-Restoration from New Fermions and Implications for Baryogenesis

    Oleksii Matsedonskyi🇮🇱 · Geraldine Servant🇩🇪

    The strength of electroweak symmetry breaking may substantially differ in the early Universe compared to the present day value. In the Standard Model, the Higgs vacuum expectation value (vev) vanishes and electroweak symmetry gets restored at temperatures above $\sim 160$ GeV due to the Higgs field interactions with the high-temperature plasma. It was however shown that new light singlet scalar fields may change this behaviour. The key feature is the non-standard dependence on the Higgs vev of the new particles mass which can vanish at large Higgs vev, inducing a negative correction to the Higgs thermal mass, leading to electroweak symmetry non-restoration at high temperature. We show that such an effect can also be induced by new singlet fermions which on the other hand have the advantage of not producing unstable directions in the scalar potential at tree level, nor bringing additional severe hierarchy problems. As temperature drops, such a high-temperature breaking phase may continuously evolve into the zero-temperature breaking phase or the two phases can be separated by a temporary phase of restored symmetry. We discuss how our construction can naturally arise in motivated models of new physics, such as Composite Higgs. This is particularly relevant for baryogenesis, as it opens a whole class of possibilities in which the baryon asymmetry can be produced during a high temperature phase transition, while not being erased later by sphalerons.

    hep-phJHEP(2020)·70 citations
18. 18*

    Conformal Bjorken flow in the general frame and its attractor: Similarities and discrepancies with the Müller-Israel-Stewart formalism

    M. Shokri🇮🇷 · F. Taghinavaz🇮🇷

    We investigate the implications of the general frame approach for conformal Bjorken flow beyond the earlier studies. We show that the power series solution at late times is not unique and is accompanied by an exact solution of the form $1/\tau$, which becomes unphysical if taken on shell. In contrast to the Müller-Israel-Stewart formalism, a matching between $\text{NFSYM}$ results and the hydro expansion is only possible up to the first order, which gives rise to $\eta /s=1/4\pi$. Matching the results to the next order gives rise to causality/stability-violating values. Furthermore, we show that the pressure anisotropy in the general frame cannot capture the hydrodynamization, and we introduce an alternative measure to find the attractor. Using slow-roll expansion, we find an analytical approximation form for the attractor. We also show that the early-time behavior of attractors is related to stability and causality conditions. The attractor solutions outside the stable and causal regime give rise to reheating and negative longitudinal pressures in early times, in contrast to the stable and causal ones. We also comment on the violation of the second law of thermodynamics by the off-shell parameters. We show that for the stable and causal choice of parameters, the off-shell canonical entropy of the attractors, which is not a physical quantity, has a negative divergence in early times before tending to its on-shell limit. On the other hand, the unstable and acausal attractors have non-negative entropy divergence. We speculate that the violation of the second law by stable and causal off-shell parameters is required for stability of the first-order hydrodynamics. We investigate the analytical structure of the Borel-transformed series and find the proper relation between the poles and nonhydro modes.

    ↳ hep-thhep-phnucl-thphysics.flu-dynPRD(2020)·23 citations
19. 19*

    The 21-cm signals from ultracompact minihalos as a probe of primordial small-scale fluctuations

    Kunihiko Furugori🇯🇵 · Katsuya Abe🇯🇵 · Toshiyuki Tanaka🇯🇵 · Daiki Hashimoto🇯🇵 · Hiroyuki Tashiro🇯🇵 · Kenji Hasegawa🇯🇵

    Ultracompact minihalos~(UCMHs) can form after the epoch of matter-radiation equality, if the density fluctuations of dark matter have significantly large amplitude on small scales. The constraint on the UCMH abundance allows us to access such small-scale fluctuations. In this paper, we present that, through the measurement of 21-cm fluctuations before the epoch of reionization~ we can obtain a constraint on the UCMH abundance. We calculate the 21-cm signal from UCMHs and show that UCMHs provide the enhancement of the 21-cm fluctuations. We also investigate the constraint on the UCMH abundance and small-scale curvature perturbations. Our results indicate that the upcoming 21-cm observation, the Square Kilometre Array (SKA), provides the constraint on amplitude of primordial curvature power spectrum, ${\mathcal{A}}_{\zeta }\lesssim 10^{-6}$ on $100{\mathrm{Mpc}}^{-1}\lesssim k\lesssim 1000{\mathrm{Mpc}}^{-1}$. Although it is not stronger than the one from the non-detection of gamma rays induced by dark matter annihilation in UCMHs, the constraint by the SKA will be important because this constraint is independent of the dark matter particle model.

    ↳ astro-ph.COhep-phMNRAS(2020)·18 citations
20. 20*

    $J$-factor estimation of Draco, Sculptor and Ursa Minor dwarf spheroidal galaxies with the member/foreground mixture model

    Shun-ichi Horigome🇯🇵 · Kohei Hayashi🇯🇵 · Masahiro Ibe🇯🇵 · Miho N. Ishigaki🇯🇵 · Shigeki Matsumoto🇯🇵 · Hajime Sugai🇯🇵

    Dwarf spheroidal galaxies (dSphs) are promising targets of indirect detection experiments searching for dark matter (DM) at present universe. Toward robust prediction for the amount of signal flux originating in DM annihilation inside dSphs, a precise determination of DM distributions as well as $J$-factors of the dSphs is particularly important. In this work, we estimate those of Draco, Sculptor, and Ursa Minor dSphs by an improved statistical method in which both foreground stars and dSph member stars are simultaneously taken into account. We define the likelihood function of the method as the so-called conditional one to remove sampling bias of observed stellar data. This improved method enables us to estimate DM distributions and $J$-factors of the dSphs directly from observed stellar data contaminated by foreground stars without imposing stringent membership criteria on the measured quantities.

    ↳ astro-ph.GAastro-ph.HEhep-phMNRAS(2020)·10 citations
21. 21*

    Three-flavour oscillations with accelerator neutrino beams

    M. Mezzetto🇮🇹 · F. Terranova🇮🇹

    The three-flavor neutrino oscillation paradigm is well established in particle physics thanks to the crucial contribution of accelerator neutrino beam experiments. In this paper we review the most important contributions of these experiments to the physics of massive neutrinos after the discovery of ${\theta }_{13}$ and future perspectives in such a lively field of research. Special emphasis is given to the technical challenges of high power beams and the oscillation results of T2K, OPERA, ICARUS and NO$\nu$A. We discuss in details the role of accelerator neutrino experiments in the precision era of neutrino physics in view of DUNE and Hyper-Kamiokande, the programme of systematic uncertainty reduction and the development of new beam facilities.

    ↳ hep-exhep-phphysics.acc-phphysics.ins-detUniverse(2020)·6 citations
22. 22*

    Strengthening the de Sitter swampland conjecture in warm inflation

    Robert Brandenberger🇨🇦 · Vahid Kamali🇨🇦 · Rudnei O. Ramos🇧🇷

    The "de Sitter constraint" on the space of effective scalar field theories consistent with superstring theory provides a lower bound on the slope of the potential of a scalar field which dominates the evolution of the Universe, e.g., a hypothetical inflaton field. Whereas models of single scalar field inflation with a canonically normalized field do not obey this constraint, it has been claimed recently in the literature that models of warm inflation can be made compatible with it in the case of large dissipation. The de Sitter constraint is known to be derived from entropy considerations. Since warm inflation necessary involves entropy production, it becomes necessary to determine how this entropy production will affect the constraints imposed by the swampland conditions. Here, we generalize these entropy considerations to the case of warm inflation and show that the condition on the slope of the potential remains essentially unchanged and is, hence, robust even in the warm inflation dynamics. We are then able to conclude that models of warm inflation indeed can be made consistent with the "swampland" criteria.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2020)·62 citations
23. 23*

    Probing the absorption of gamma-rays by IR radiation from the dusty torus in FSRQs with the Cherenkov Telescope Array

    Giorgio Galanti🇮🇹 · Marco Landoni🇮🇹 · Fabrizio Tavecchio🇮🇹 · Stefano Covino🇮🇹

    Within the classical emission model, where the emission region is placed within the broad line region (BLR), flat spectrum radio quasars (FSRQs) were believed not to emit photons with energies above few tens of GeV because of the absorption with the optical-UV photons from the BLR. However, photons with observed energies up to about $300\mathrm{GeV}$ have been detected for few FSRQs, whose most iconic example is PKS 1441+25 at redshift $z=0.94$. The most conservative explanation for these observations is that the emission occurs at distances comparable to the size of the dusty torus. In this case, absorption of high-energy gamma-ray photons for energies above $200-300\mathrm{GeV}$ is dominated by the interaction with infrared radiation emitted by the torus. We investigate if current observational data about FSRQs in flaring state can give us information about: (i) the importance of the torus absorption and (ii) the properties of the torus i.e. its temperature and its geometry. We find that present data do not arrive at energies where the torus influence is prominent and as a result it is currently hardly possible to infer torus properties from observations. However, with dedicated simulations, we demonstrate that observations with the forthcoming Cherenkov Telescope Array (CTA) will be able to constrain the torus parameters (temperature and geometry).

    ↳ astro-ph.HEhep-phMNRAS(2020)·8 citations
24. 24*

    Probing the Seesaw Mechanism with Cosmological Data

    J. G. Rodrigues🇧🇷 · Micol Benetti🇮🇹 · Marcela Campista🇧🇷 · Jailson Alcaniz🇧🇷

    We investigate cosmological consequences of an inflationary model which incorporates a generic seesaw extension (types I and II) of the Standard Model of Particle Physics. A non-minimal coupling between the inflaton field and the Ricci scalar is considered as well as radiative corrections at one loop order. This connection between the inflationary dynamics with neutrino physics results in a predictive model whose observational viability is investigated in light of the current cosmic microwave background data, baryon acoustic oscillation observations and type Ia supernovae measurements. Our results show that the non-minimal coupled seesaw potential provides a good description of the observational data when radiative corrections are positive. Such result favours the type II seesaw mechanism over type I and may be an indication for physics beyond the Standard Model.

    ↳ astro-ph.COgr-qchep-phJCAP(2020)·21 citations
25. 25*

    Dilaton EFT from p-regime to RMT in the $ϵ$-regime

    Zoltan Fodor🇩🇪 · Kieran Holland🇺🇸 · Julius Kuti🇺🇸 · Chik Him Wong🇩🇪

    New results are reported from tests of a low-energy effective field theory (EFT) that includes a dilaton field to describe the emergent light scalar with $0^{++}$ quantum numbers in the strongly coupled near-conformal gauge theory with a massless fermion flavor doublet in the two-index symmetric (sextet) representation of the SU(3) color gauge group. In the parlor of walking --- based on the observed light scalar, the small $\beta$-function at strong coupling, and the large anomalous scale dimension of the chiral condensate --- the dilaton EFT hypothesis is introduced to test if it explains the slowly changing nearly scale invariant physics that connects the asymptotically free UV fixed point and the far-infrared scale of chiral symmetry breaking. The characteristic dilaton EFT signatures of scale symmetry breaking are probed in this report in the small Compton wavelength limit of Goldstone bosons relative to the size of the lattice volume (p-regime) and in the limit when the Goldstone wavelength exceeds the size of the volume ($ϵ$-regime). Random matrix theory (RMT) analysis of the dilaton EFT is applied to the lowest part of the Dirac spectrum in the $ϵ$-regime to directly test predictions for the fundamental EFT parameters. The predictions, sensitive to the choice of the dilaton potential, were limited before to the p-regime, using extrapolations from far above the chiral limit with untested uncertainties. The dilaton EFT analysis of the $ϵ$-regime was first suggested in \cite{Fodor:2019vmw}, with some results presented at this conference and with our continued post-conference analysis added to stimulate discussions.

    ↳ hep-lathep-phPoS(2020)·34 citations
26. 26*

    Dark Photon Oscillations in Our Inhomogeneous Universe

    Andrea Caputo🇪🇸 · Hongwan Liu🇺🇸 · Siddharth Mishra-Sharma🇺🇸 · Joshua T. Ruderman🇺🇸

    A dark photon may kinetically mix with the ordinary photon, inducing oscillations with observable imprints on cosmology. Oscillations are resonantly enhanced if the dark photon mass equals the ordinary photon plasma mass, which tracks the free electron number density. Previous studies have assumed a homogeneous Universe; in this Letter, we introduce for the first time an analytic formalism for treating resonant oscillations in the presence of inhomogeneities of the photon plasma mass. We apply our formalism to determine constraints from Cosmic Microwave Background photons oscillating into dark photons, and from heating of the primordial plasma due to dark photon dark matter converting into low-energy photons. Including the effect of inhomogeneities demonstrates that prior homogeneous constraints are not conservative, and simultaneously extends current experimental limits into a vast new parameter space.

    ↳ astro-ph.COhep-phPRL(2020)·152 citations
27. 27*

    Connecting Dualities and Machine Learning

    Philip Betzler🇩🇪 · Sven Krippendorf🇩🇪

    Dualities are widely used in quantum field theories and string theory to obtain correlation functions at high accuracy. Here we present examples where dual data representations are useful in supervised classification, linking machine learning and typical tasks in theoretical physics. We then discuss how such beneficial representations can be enforced in the latent dimension of neural networks. We find that additional contributions to the loss based on feature separation, feature matching with respect to desired representations, and a good performance on a `simple' correlation function can lead to known and unknown dual representations. This is the first proof of concept that computers can find dualities. We discuss how our examples, based on discrete Fourier transformation and Ising models, connect to other dualities in theoretical physics, for instance Seiberg duality.

    ↳ physics.comp-phcond-mat.dis-nncs.LGhep-ph+2Fortsch.Phys.(2020)·16 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.