Tue·Feb 25, 2020Tuesday·February 25, 2020

1. 01*

   Quasinormal modes and thermalization in Improved Holographic QCD

   Timo Alho🇫🇮 · Jere Remes🇫🇮 · Kimmo Tuominen🇫🇮 · Aleksi Vuorinen🇫🇮

   Following a series of similar calculations in simpler non-conformal holographic setups, we determine the quasinormal mode spectrum for an operator dual to a gauge-invariant scalar field within the Improved Holographic QCD framework. At temperatures somewhat above the critical temperature of the deconfinement transition, we find a small number of clearly separated modes followed by a branch-cut-like structure parallel to the real axis, the presence of which is linked to the form of the IHQCD potential employed. The temperature dependence of the lowest nonzero mode is furthermore used to study the thermalization time of the corresponding correlator, which is found to be of the order of the inverse critical temperature near the phase transition and decrease slightly faster than $1/T$ at higher temperatures.

   hep-phhep-thPRD(2020)·10 citations
2. 02*

   Decay Properties of Conventional and Hybrid Charmonium Mesons

   Nosheen Akbar🇵🇰

   In this paper, Schrodinger equation is numerically applied through non-relativistic potential model for deriving Spectrum, radial wave functions at origin, decay constants, lepton and photon decay widths for radial and orbital excited conventional as well as hybrid charmonium mesons. These calculated results are found in agreement with others theoretical results and with the experimental observations.

   hep-phJ.Korean Phys.Soc.(2020)·8 citations
3. 03*

   Mixing effects of ${\Sigma }^0-{\Lambda }^0$ in ${\Lambda }_c^{+}$ decays

   C.Q. Geng🇨🇳 · Chia-Wei Liu🇹🇼 · Tien-Hsueh Tsai🇹🇼

   We analyze the mixing between ${\Sigma }^0$ and ${\Lambda }^0$ based on the baryon masses. We distinguish the contributions from QCD and QED in the baryon mass splittings. We find that the mixing angle between ${\Sigma }^0$ and ${\Lambda }^0$ is $(2.07\pm 0.03)\times 10^{-2}$, which leads to the decay branching fraction and up-down asymmetry of ${\Lambda }_c^{+}\to {\Sigma }^0{e}^{+}{\nu }_e$ to be $\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^0{e}^{+}{\nu }_e)=(1.5\pm 0.2)\times 10^{-5}$ and $\alpha ({\Lambda }_c^{+}\to {\Sigma }^0{e}^{+}{\nu }_e)=-0.86\pm 0.04$, respectively. Moreover, we obtain that $\Delta \mathcal{B}\equiv \mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^0{\pi }^{+})-\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0)=(3.8\pm 0.5)\times 10^{-4}$ and $\Delta \alpha \equiv \alpha ({\Lambda }_c^{+}\to {\Sigma }^0{\pi }^{+})-\alpha ({\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0)=(-1.6\pm 0.7)\times 10^{-2}$, which should vanish without the mixing.

   hep-phhep-exPRD(2020)·7 citations
4. 04*

   Hadronic decays of the $J/\psi$ meson

   Alessio Mangoni🇮🇹

   In this work we propose mainly phenomenological and theoretical models that allow, together with the use of the available experimental data, the calculation of form factors (FFs) and decay amplitudes. We focus our attention firstly on the $J/\psi$ decay into a pair of pions, showing that this process does not proceed only electromagnetically as believed so far, due to the presence of a non-negligible mixed strong-EM contribution to the total branching ratio. Moreover we consider the decay of the $J/\psi$ meson into a pair of baryon-antibaryon, where we separate, for the first time, the single strong, electromagnetic and strong-EM contributions to the total BR and the relative Feynman amplitudes, obtaining also the relative phase between the strong and the electromagnetic ones.

   hep-ph3 citations
5. 05*

   Incoherent $\rho$ meson photoproduction in ultraperipheral nuclear collisions at the LHC

   V. Guzey🇷🇺 · E. Kryshen🇷🇺 · M. Zhalov (St. Petersburg, INP)🇷🇺

   Using the Gribov-Glauber model for photon-nucleus scattering and a generalization of the vector meson dominance model for the hadronic structure of the photon, we make predictions for the cross section of incoherent $\rho$ photoproduction in Pb-Pb ultraperipheral collisions (UPCs) in the Large Hadron Collider kinematics. We find that the effect of the inelastic nuclear shadowing is significant and leads to an additional 25% suppression of the incoherent cross section. Comparing our predictions to those of the STARlight Monte Carlo framework, we observe very significant differences.

   hep-phhep-exnucl-exPRC(2020)·6 citations
6. 06*

   Hadronic cross section of $e^{+}{e}^{-}$ annihilation at bottomonium energy region

   Xiang-Kun Dong🇨🇳 · Xiao-Hu Mo🇨🇳 · Ping Wang🇨🇳 · Chang-Zheng Yuan🇨🇳

   The Born cross section and dressed cross section of $e^{+}{e}^{-}$ to $b\bar{b}$ and the total hadronic cross section in $e^{+}{e}^{-}$ annihilation in the bottomonium energy region are calculated based on the Rb values measured by the BaBar and Belle experiments. The data are used to calculate the vacuum polarization factors in the bottomonium energy region, and to determine the resonant parameters of the vector bottomonium(-like) states, the Y(10750), Upsilon(5S), and Upsilon(6S).

   hep-phhep-exCPC(2020)·42 citations
7. 07*

   Revisiting the $B$-physics anomalies in $R$-parity violating MSSM

   Quan-Yi Hu🇨🇳 · Ya-Dong Yang🇨🇳 · Min-Di Zheng🇨🇳

   In recent years, several deviations from the Standard Model predictions in semileptonic decays of $B$-meson might suggest the existence of new physics which would break the lepton-flavour universality. In this work, we have explored the possibility of using muon sneutrinos and right-handed sbottoms to solve these $B$-physics anomalies simultaneously in $R$-parity violating minimal supersymmetric standard model. We find that the photonic penguin induced by exchanging sneutrino can provide sizable lepton flavour universal contribution due to the existence of logarithmic enhancement for the first time. This prompts us to use the two-parameter scenario $(C_9^{\mathrm{V}},C_9^{\mathrm{U}})$ to explain $b\to s{\ell }^{+}{\ell }^{-}$ anomaly. Finally, the numerical analyses show that the muon sneutrinos and right-handed sbottoms can explain $b\to s{\ell }^{+}{\ell }^{-}$ and $R(D^{(\ast )})$ anomalies simultaneously, and satisfy the constraints of other related processes, such as $B\to K^{(\ast )}\nu \bar{\nu }$ decays, $B_s-{\bar{B}}_s$ mixing, $Z$ decays, as well as $D^0\to {\mu }^{+}{\mu }^{-}$, $\tau \to \mu {\rho }^0$, $B\to \tau \nu$, $D_s\to \tau \nu$, $\tau \to K\nu$, $\tau \to \mu \gamma$, and $\tau \to \mu \mu \mu$ decays.

   hep-phEPJC(2020)·41 citations
8. 08*

   The Collectivity of Heavy Mesons in Proton-Nucleus Collisions

   Cheng Zhang🇨🇳 · Cyrille Marquet🇫🇷 · Guang-You Qin🇨🇳 · Yu Shi🇨🇳 · Lei Wang🇨🇳 · Shu-Yi Wei🇮🇹 · Bo-Wen Xiao🇨🇳

   Using a model based on the Color Glass Condensate framework and the dilute-dense factorization, we systematically study the azimuthal angular correlations between a heavy flavor meson and a light reference particle in proton-nucleus collisions. The obtained second harmonic coefficients (also known as the elliptic flows) for $J/\psi$ and $D^0$ agree with recent experimental data from the LHC. We also provide predictions for the elliptic flows of ${\rm Y}$ and $B$ meson, which can be measured in the near future at the LHC. This work can shed light on the physics origin of the collectivity phenomenon in the collisions of small systems.

   hep-phnucl-exnucl-thPRD(2020)·37 citations
9. 09*

   New features in the JHU generator framework: constraining Higgs boson properties from on-shell and off-shell production

   Andrei V. Gritsan🇺🇸 · Jeffrey Roskes🇺🇸 · Ulascan Sarica🇺🇸 · Markus Schulze🇩🇪 · Meng Xiao🇺🇸 · Yaofu Zhou🇨🇳

   We present an extension of the JHUGen and MELA framework, which includes an event generator and library for the matrix element analysis. It enables simulation, optimal discrimination, reweighting techniques, and analysis of a bosonic resonance and the triple and quartic gauge boson interactions with the most general anomalous couplings. The new features, which become especially relevant at the current stage of LHC data taking, are the simulation of gluon fusion and vector boson fusion in the off-shell region, associated $ZH$ production at NLO QCD including the $gg$ initial state, and the simulation of a second spin-zero resonance. We also quote translations of the anomalous coupling measurements into constraints on dimension-six operators of an effective field theory. Some of the new features are illustrated with projections for experimental measurements with the full LHC and HL-LHC datasets.

   hep-phhep-exPRD(2020)·96 citations
10. 10*

    The Spin Alignment of Vector Mesons in High Energy pp Collisions

    Kai-bao Chen🇨🇳 · Zuo-tang Liang🇨🇳 · Yu-kun Song🇨🇳 · Shu-yi Wei🇮🇹

    The spin alignment of vector meson produced in high energy reactions is determined by the spin-dependent fragmentation function $D_{1LL}(z,{\mu }_f)$ that is shown to be independent of the polarization of the fragmenting quark. In this paper, we extract the spin-dependent fragmentation function $D_{1LL}(z,{\mu }_f)$ from data on the spin alignment of $K^{\ast 0}$ in $e^{+}{e}^{-}$ annihilation at LEP in two different scenarios and apply them to make predictions in $pp$ collisions. We make detailed analysis of contributions from different sub-processes and show that the spin alignment should be quite significant also in high energy $pp$ collisions.

    hep-phPRD(2020)·26 citations
11. 11*

    Observational constraints on dark matter decaying via gravity portals

    Sun Xu-Dong🇨🇳 · Dai Ben-Zhong🇨🇳

    Global symmetry can guarantee the stability of dark matter particles (DMps). However, the nonminimal coupling between dark matter (DM) and gravity can destroy the global symmetry of DMps, which in turn leads to their decay. Under the framework of nonminimal coupling between scalar singlet dark matter (ssDM) and gravity, it is worth exploring to what extent the symmetry of ssDM is broken. It is suggested that the total amount of decay products of ssDM cannot exceed current observational constraints. Along these lines, the data obtained with satellites such as Fermi-LAT and AMS-02 can limit the strength of the global symmetry breaking of ssDM. Since the mass of many well--motivated DM candidates may be in the GeV--TeV range, we determine a reasonable parameter range for the lifetime in this range. We find that when the mass of the ssDM is around the electroweak scale (246 GeV), the corresponding 3--$\sigma$ lower limits of the lifetime of ssDM is $5.3\times 10^{26}$ s. Our analysis of ssDM around the typical electroweak scale contains the most abundant decay channels of all mass range, so the analysis of the behaviour of ssDM under the influence of gravity is more comprehensive.

    hep-phastro-ph.COCPC(2020)·5 citations
12. 12*

    Singlet Fermionic Dark Matter with Dark $Z$

    Dong-Won Jung🇰🇷 · Soo-hyeon Nam🇰🇷 · Chaehyun Yu🇰🇷 · Yeong Gyun Kim🇰🇷 · Kang Young Lee🇰🇷

    We present a fermionic dark matter model mediated by the hidden gauge boson. We assume the QED-like hidden sector which consists of a Dirac fermion and U(1)${}_X$ gauge symmetry, and introduce an additional scalar electroweak doublet field with the U(1)${}_X$ charge as a mediator. The hidden U(1)${}_X$ symmetry is spontaneously broken by the electroweak symmetry breaking and there exists a massive extra neutral gauge boson in this model which is the mediator between the hidden and visible sectors. Due to the U(1)${}_X$ charge, the additional scalar doublet does not couple to the Standard Model fermions, which leads to the Higgs sector of type I two Higgs doublet model. The new gauge boson couples to the Standard Model fermions with couplings proportional to those of the ordinary $Z$ boson but very suppressed, thus we call it the dark $Z$ boson. We study the phenomenology of the dark $Z$ boson and the Higgs sector, and show the hidden fermion can be the dark matter candidate.

    hep-phEPJC(2020)·15 citations
13. 13*

    Cosmogenic neutrino fluxes under the effect of active-sterile secret interactions

    Damiano F. G. Fiorillo🇮🇹 · Gennaro Miele🇮🇹 · Stefano Morisi🇮🇹 · Ninetta Saviano🇮🇹

    Ultra High Energy cosmogenic neutrinos may represent a unique opportunity to unveil possible new physics interactions once restricted to the neutrino sector only. In the present paper we study the observable effects of a secret active-sterile interactions, mediated by a pseudoscalar, on the expected flux of cosmogenic neutrinos. The results show that for masses of sterile neutrinos and pseudoscalars of hundreds MeV, necessary to evade cosmological, astrophysical and elementary particle constraints, the presence of such new interactions can significantly change the energy spectrum of cosmogenic neutrinos at Earth in the energy range from PeV to ZeV. Interestingly, the distortion of the spectrum results to be detectable at GRAND apparatus if the scalar mediator mass is around 250 MeV and the UHECRs are dominated by the proton component. Larger mediator masses or a chemical composition of UHECRs dominated by heavier nuclei would require much larger cosmic rays apparatus which might be available in future.

    hep-phastro-ph.HEPRD(2020)·14 citations
14. 14*

    Perturbative Thermal QCD: Formalism and Applications

    Jacopo Ghiglieri🇫🇷 · Aleksi Kurkela🇨🇭 · Michael Strickland🇺🇸 · Aleksi Vuorinen🇫🇮

    In this review article, we discuss the current status and future prospects of perturbation theory as a means of studying the equilibrium thermodynamic and near-equilibrium transport properties of deconfined QCD matter. We begin with a brief introduction to the general topic, after which we review in some detail the foundations and modern techniques of the real- and imaginary-time formalisms of thermal field theory, covering e.g. the different bases used in the real-time formalism and the resummations required to deal with soft and collinear contributions. After this, we discuss the current status of applications of these techniques, including topics such as electromagnetic rates, transport coefficients, jet quenching, heavy quarks and quarkonia, and the Equations of State of hot quark-gluon plasma as well as cold and dense quark matter. Finally, we conclude with our view of the future directions of the field, i.e. how we anticipate perturbative calculations to contribute to our collective understanding of strongly interacting matter in the coming years.

    hep-phhep-thnucl-thPhys.Rept.(2020)·193 citations
15. 15*

    Muon and Electron $g-2$ and the Origin of Fermion Mass Hierarchy

    Naoyuki Haba🇯🇵 · Yasuhiro Shimizu🇯🇵 · Toshifumi Yamada🇯🇵

    We present a model that gives a natural explanation to the charged lepton mass hierarchy and study the contributions to the electron and the muon $g-2$. In the model, we introduce lepton-flavor-dependent $U(1{)}_F$ symmetry and three additional Higgs doublets with $U(1{)}_F$ charges, to realize that each generation of charged leptons couples to one of the three additional Higgs doublets. The $U(1{)}_F$ symmetry is softly broken by $+1$ charges, and the smallness of the soft breaking naturally gives rise to the hierarchy of the Higgs VEVs, which then accounts for the charged lepton mass hierarchy. Since electron and muon couple to different scalar particles, each scalar contributes to the electron and the muon $g-2$ differently. We survey the space of parameters of the Higgs sector and find that there are sets of parameters that explain the muon $g-2$ discrepancy. On the other hand, we cannot find the parameter sets that can explain $g-2$ discrepancy within 2$\sigma$. Here the $U(1{)}_F$ symmetry suppresses charged lepton flavor violation.

    hep-phPTEP(2020)·37 citations
16. 16*

    Studies of heavy-ion collisions using PYTHIA Angantyr and UrQMD

    André Vieira da Silva🇧🇷 · Willian Matioli Serenone🇧🇷 · David Dobrigkeit Chinellato🇧🇷 · Jun Takahashi🇧🇷 · Christian Bierlich🇸🇪

    In this paper, we show predictions from a new QGP-free, no-equilibration, improved baseline model for heavy-ion collisions. It is comprised of the PYTHIA Angantyr event generator coupled to UrQMD, as a hadronic cascade simulator, and compared to ALICE and CMS data from Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. This coupling is made possible due to a new implementation of the hadron vertex model in PYTHIA Angantyr. Hadronic rescattering in UrQMD is shown to lead to a significant suppression of mid- to high-$p_{\perp }$ particle yields that is qualitatively consistent with measurements of nuclear modification factors. We further study the effect of hadronic rescatterings on high-$p_{\perp }$ particles by using two-particle correlations and show that some suppression of away-side jets occurs in the hadronic phase even without any partonic energy loss. Finally, the decorrelation of dijet structures at high momenta also leads to a reduction of the elliptic flow coefficient $v_2\{2\}$. These findings suggest that significant jet-quenching-like effects may still originate in the hadronic, as opposed to the partonic phase and prove that the usual Pb-Pb baseline, composed of a superposition of incoherent pp collisions, ignores coherent phenomena that are not strictly related to the QGP but may still be highly relevant.

    hep-ph19 citations
17. 17*

    Constraints on light singlet fermion interactions from coherent elastic neutrino-nucleus scattering

    We-Fu Chang🇹🇼 · Jiajun Liao🇨🇳

    The exotic singlet fermions $\chi$, with a mass $m_{\chi }\lesssim 50$ MeV, could be produced at the coherent elastic neutrino-nucleus scattering (CE$\nu$NS) experiments through the $\nu \mathcal{N}\to \chi \mathcal{N}$ process. Due to the coherent enhancement, it offers a unique way to study how $\chi$ interacts with the Standard Model (SM) sector. Based on the most general dimension-6 effective Lagrangian, we perform a comprehensive study on the relevant interaction between $\chi$ and the SM sector. From the current and future COHERENT and future CONUS experiments, we obtain the upper bounds on the Wilson coefficients for the dipole, scalar, vector, and tensor interactions. For $m_{\chi }$ below 10 MeV, future CONUS data has the best sensitivity, while for $m_{\chi }$ between 10 MeV$-50$ MeV, the current and future COHERENT bounds dominate. These limits are complementary to those from neutrino oscillation and collider searches. Moreover, the bounds do not depend on the charge conjugation property of $\chi$, nor whether $\chi$ is dark matter or not.

    hep-phPRD(2020)·31 citations
18. 18*

    Quark-diquark string tension, excited baryonic resonances and thermal fluctuations

    E. Megias🇪🇸 · E. Ruiz Arriola🇪🇸 · L.L. Salcedo🇪🇸

    We study the baryonic fluctuations from second to eighth order involving electric charge, baryon number and strangeness below the quark-gluon plasma crossover and numerically known from lattice QCD calculations. By considering a particular realization of the Hadron Resonance Gas model, we provide evidence on the dominant role of quark-diquark degrees of freedom to describe excited baryonic resonances. After proving by means of suitable Polyakov loop correlators that the quark-diquark and the quark-antiquark forces coincide, $V_{\bar{q}q}(r)=V_{\bar{q}D}(r)+\text{const}$, we find that the corresponding susceptibilities can be saturated with excited baryonic states in a quark-diquark model picture.

    hep-phhep-latnucl-thPhys.Scripta(2020)·2 citations
19. 19*

    Is the K-matrix approach adequate for describing overlapping resonances?

    Victor Henner🇷🇺 · Tatyana Belozerova🇷🇺

    The K-matrix method is widely used unitary parametrization for several resonances with the same quantum numbers. But in fact resonances in this approach are separated and do not overlap.

    hep-ph0 citations
20. 20*

    Oscillating Strange Quark Matter Objects Excited in Stellar Systems

    Marek Kutschera (1)🇵🇱 · Łukasz Bratek (2)🇵🇱 · Joanna Jałocha (2)🇵🇱 · Sebastian Kubis (2)🇵🇱 · Tomasz Kędziorek (1) ((1) Jagiellonian University, Kraków, Poland, (2) Cracow University of Technology, Kraków, Poland)

    It is shown that strange quark matter (SQM) objects, stars, and planets, can very efficiently convert the mechanical energy into hadronic energy when they oscillate. This is because the mass density at the edge of SQM objects, ${\rho }_0=4.7\times 10^{14}\frac{\mathrm{g}}{{\mathrm{cm}}^3}$, is the critical density below which SQM is unstable with respect to decay into photons, hadrons, and leptons. We consider here radial oscillations of SQM objects that could be induced in stellar or planetary systems where tidal interactions are ubiquitous. Oscillations of $0.1\%$ radius amplitude already result in $1$keV per unit baryon number excitation near the surface of SQM stars. The excitation energy is converted into electromagnetic energy in a short time of 1 ms, during a few oscillations. Higher amplitude oscillations result in faster energy release that could lead to fragmentation or dissolution of SQM stars. This would have significant consequences for hypothetical SQM star binaries and planetary systems of SQM planets with regard to gravitational wave emission.

    ↳ astro-ph.HEhep-phApJ(2020)·5 citations
21. 21*

    Ultrarelativistic quark-nucleus scattering in a light-front Hamiltonian approach

    Meijian Li🇺🇸 · Xingbo Zhao🇨🇳 · Pieter Maris🇺🇸 · Guangyao Chen🇺🇸 · Yang Li🇺🇸 · Kirill Tuchin🇺🇸 · James P. Vary🇺🇸

    We investigate the scattering of a quark on a heavy nucleus at high energies using the time-dependent basis light-front quantization (tBLFQ) formalism, which is the first application of the tBLFQ formalism in QCD. We present the real-time evolution of the quark wave function in a strong classical color field of the relativistic nucleus, described as the Color Glass Condensate. The quark and the nucleus color field are simulated in the QCD SU(3) color space. We calculate the total and the differential cross sections, and the quark distribution in coordinate and color spaces using the tBLFQ approach. We recover the eikonal cross sections in the eikonal limit. We find that the differential cross section from the tBLFQ simulation is in agreement with a perturbative calculation at large $p_{\perp }$, and it deviates from the perturbative calculation at small $p_{\perp }$ due to higher-order contributions. In particular, we relax the eikonal limit by letting the quark carry realistic finite longitudinal momenta. We study the sub-eikonal effect on the quark through the transverse coordinate distribution of the quark with different longitudinal momentum, and we find the sub-eikonal effect to be sizable. Our results can significantly reduce the theoretical uncertainties in small $p_{\perp }$ region which has important implications to the phenomenology of the hadron-nucleus and deep inelastic scattering at high energies.

    ↳ nucl-thhep-phPRD(2020)·38 citations
22. 22*

    Creating Spatial Flatness by Combining String Gas Cosmology and Power Law Inflation

    Vahid Kamali🇨🇦 · Robert Brandenberger (McGill University)🇨🇦

    We show that it is possible to combine an early phase of String Gas Cosmology which can explain the origin of the observed structures on cosmological scales with a short later period of power law inflation which creates spatial flatness. The resulting model is consistent with the ``swampland criteria'' and the constraints coming from the {\it Trans-Planckian Censorship Conjecture}. Such a construction is not possible using only canonical slow-roll inflation, but it can emerge in the warm inflation scenario or in cold inflation with an exponential potential. The resulting cosmology is non-singular. We discuss the spectrum of cosmological perturbations resulting in our scenario. On large scales (scales which remain larger than the Hubble radius after the initial string gas phase) the spectrum is determined by the thermal string gas fluctuations set up in the primordial phase, and it is almost scale-invariant with a slight red tilt. On small scales, the perturbations produced during the inflationary phase dominate. On these scales, the spectrum is once again nearly scale-invariant. There is an intermediate range (scales which enter the Hubble radius during the period of inflation) where the string gas fluctuations are damped but continue to dominate over those produced during the period of inflation. On these scales the spectrum has a sharp red spectral index of $n_s-1\sim -2$.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2020)·13 citations
23. 23*

    Bryan's Maximum Entropy Method -- diagnosis of a flawed argument and its remedy

    Alexander Rothkopf🇳🇴

    The Maximum Entropy Method (MEM) is a popular data analysis technique based on Bayesian inference, which has found various applications in the research literature. While the MEM itself is well-grounded in statistics, I argue that its state-of-the-art implementation, suggested originally by Bryan, artificially restricts its solution space. This restriction leads to a systematic error often unaccounted for in contemporary MEM studies. The goal of this paper is to carefully revisit Bryan's train of thought, point out its flaw in applying linear algebra arguments to an inherently nonlinear problem, and suggest possible ways to overcome it.

    ↳ physics.data-anhep-lathep-phnucl-th+1Data 2020, 5(3), 85·9 citations
24. 24*

    Event Classification with Quantum Machine Learning in High-Energy Physics

    Koji Terashi🇯🇵 · Michiru Kaneda🇯🇵 · Tomoe Kishimoto🇯🇵 · Masahiko Saito🇯🇵 · Ryu Sawada🇯🇵 · Junichi Tanaka🇯🇵

    We present studies of quantum algorithms exploiting machine learning to classify events of interest from background events, one of the most representative machine learning applications in high-energy physics. We focus on variational quantum approach to learn the properties of input data and evaluate the performance of the event classification using both simulators and quantum computing devices. Comparison of the performance with standard multi-variate classification techniques based on a boosted-decision tree and a deep neural network using classical computers shows that the quantum algorithm has comparable performance with the standard techniques at the considered ranges of the number of input variables and the size of training samples. The variational quantum algorithm is tested with quantum computers, demonstrating that the discrimination of interesting events from background is feasible. Characteristic behaviors observed during a learning process using quantum circuits with extended gate structures are discussed, as well as the implications of the current performance to the application in high-energy physics experiments.

    ↳ physics.comp-phhep-exhep-phquant-phComput.Softw.Big Sci.(2021)·66 citations
25. 25*

    One-loop order effects from one universal extra dimension on $\lambda {\varphi }^4$ theory

    M. A. López-Osorio🇲🇽 · E. Martínez-Pascual🇲🇽 · G. I. Nápoles-Cañedo🇲🇽 · J. J. Toscano🇲🇽

    The self-interacting $\lambda {\varphi }^4$ scalar field theory is a warhorse in quantum field theory. Here we explore the one-loop order impact from one universal extra dimension, $S^1/{\mathbb{Z}}_2$, to the self-energy and four point vertex functions associated to this theory. Such effects come as an infinite number of UV divergences corresponding to an infinite superposition of excited KK particles around the loop. We show that dimensional regularisation is adequate enough to control them in terms of the product of the one dimensional inhomogenous Epstein zeta function times the gamma function. From the analytical properties of these functions, the UV divergences are extracted and the counterterms defined; the latter turn out to be of canonical dimension four at the Lagrangian level. We use both, the MS-scheme and a mass-dependent subtraction scheme to remove divergences. Only the latter manifestly satisfy the decoupling theorem.

    ↳ hep-thhep-phJ.Phys.Comm.(2020)·2 citations
26. 26*

    On Seminal HEDP Research Opportunities Enabled by Colocating Multi-Petawatt Laser with High-Density Electron Beams

    Sebastian Meuren🇺🇸 · Phil H. Bucksbaum🇺🇸 · Nathaniel J. Fisch🇺🇸 · Frederico Fiúza🇺🇸 · Siegfried Glenzer🇺🇸 · Mark J. Hogan🇺🇸 · Kenan Qu🇺🇸 · David A. Reis🇺🇸 · Glen White🇺🇸 · Vitaly Yakimenko🇺🇸

    The scientific community is currently witnessing an expensive and worldwide race to achieve the highest possible light intensity. Within the next decade this effort is expected to reach nearly $10^{24}\mathrm{W}/\mathrm{c}{\mathrm{m}}^2$ in the lab frame by focusing of 100 PW, near-infrared lasers. A major driving force behind this effort is the possibility to study strong-field vacuum breakdown and an accompanying electron-positron pair plasma via a quantum electrodynamic (QED) cascade [Edwin Cartlidge, "The light fantastic", Science 359, 382 (2018)]. Whereas Europe is focusing on all-optical 10 PW-class laser facilities (e.g., Apollon and ELI), China is already planning on co-locating a 100 PW laser system with a 25 keV superconducting XFEL and thus implicitly also a high-quality electron beam [Station of Extreme Light (SEL) at the Shanghai Superintense-Ultrafast Lasers Facility (SULF)]. This white paper elucidates the seminal scientific opportunities facilitated by colliding dense, multi-GeV electron beams with multi-PW optical laser pulses. Such a multi-beam facility would enable the experimental exploration of extreme HEDP environments by generating electron-positron pair plasmas with unprecedented densities and temperatures, where the interplay between strong-field quantum and collective plasma effects becomes decisive.

    ↳ physics.plasm-phhep-ph51 citations
27. 27*

    Signatures of the vortical quark-gluon plasma in hadron yields

    ExHIC-P Collaboration · Hidetoshi Taya · Aaron Park · Sungtae Cho · Philipp Gubler · Koichi Hattori · Juhee Hong · Xu-Guang Huang · Su Houng Lee · Akihiko Monnai · Akira Ohnishi · Makoto Oka · Di-Lun Yang

    We investigate the hadron production from the vortical quark-gluon plasma created in heavy-ion collisions. Based on the quark-coalescence and statistical hadronization models, we show that total hadron yields summed over the spin components are enhanced by the local vorticity with quadratic dependence. The enhancement factor amounts to be a few percent and may be detectable within current experimental sensitivities. We also show that the effect is stronger for hadrons with larger spin, and thus propose a new signature of the local vorticity, which may be detected by the yield ratio of distinct hadron species having different spins such as $\varphi$ and ${\eta }^{\prime }$. The vorticity dependence of hadron yields seems robust, with consistent predictions in both of the hadron production mechanisms for reasonable values of the vorticity strength estimated for heavy-ion collisions.

    ↳ nucl-thhep-phnucl-exPRC(2020)·14 citations
28. 28*

    Fast-rotating galaxies do not depart from the MOND mass-asymptotic-speed relation

    Mordehai Milgrom🇮🇱

    Ogle et al. have fallaciously argued recently that fast-rotating disc galaxies break with the predictions of MOND: the 6 fastest rotators of the 23 galaxies in their sample appear to have higher rotational speeds than is consistent with the MOND relation between the baryonic mass of a galaxy, $M$, and its `rotational speed', $V$. They interpret this departure as a break in the observed $M-V$ relation from a logarithmic slope near the MOND-predicted $4$, to a shallow slope of $\approx 0$. However, Ogle et al. use the MAXIMAL rotational speed of the galaxies, $V_{max}$, not the ASYMPTOTIC one, $V_{\infty }$, which appears in the MOND prediction, $V_{\infty }^4=MG{a}_0$. Plotting their $M$ vs. $V_{max}$ pairs on an $M$ vs. $V_{\infty }$ plot from Lelli et al. (2016), they arrive erroneously at the above tension with MOND. The $H_{\alpha }$ rotation curves used by Ogle et al. are far too short reaching to probe the asymptotic regime, and determine $V_{\infty }$. However, it is well documented for fast rotators with observed, extended, HI rotation curves, that they can have $V_{max}$ considerably larger than the MOND-relevant $V_{\infty }$ [Noordermeer and Verheijen (NV) (2007) and others]. E.g., the fastest rotator in the NV sample has $V_{max}\approx 490km/s$, but $V_{\infty }\approx 250km/s$. NV also show that in a (MOND-irrelevant) $M-V_{max}$ plot the high-speed galaxies fall off the power-law line defined by the lower-speed ones, creating a break in the $M$ vs. $V$ relation, in just the way claimed by Ogle et al. But, when plotting the MOND-relevant $M$ vs. $V_{\infty }$ all galaxies fall near the same power-law relation, without a break.

    ↳ astro-ph.GAgr-qchep-ph1 citation
29. 29*

    Black Hole as a Quantum Field Configuration

    Hikaru Kawai🇯🇵 · Yuki Yokokura🇯🇵

    We describe 4D evaporating black holes as quantum field configurations by solving the semi-classical Einstein equation $G_{\mu \nu }=8\pi G⟨\psi |T_{\mu \nu }|\psi ⟩$ and quantum matter fields in a self-consistent manner. As the matter fields we consider $N$ massless free scalar fields ($N$ is large). We find a spherically symmetric self-consistent solution of the metric $g_{\mu \nu }$ and state $|\psi ⟩$. Here, $g_{\mu \nu }$ is locally $Ad{S}_2\times S^2$ geometry, and $|\psi ⟩$ provides $⟨\psi |T_{\mu \nu }|\psi ⟩=⟨0|T_{\mu \nu }|0⟩+T_{\mu \nu }^{(\psi )}$, where $|0⟩$ is the ground state of the matter fields in the metric and $T_{\mu \nu }^{(\psi )}$ consists of the excitation of s-waves that describe the collapsing matter and Hawking radiation with the ingoing negative energy flow. This object is supported by a large tangential pressure $⟨0|T^{\theta }{}_{\theta }|0⟩$ due to the vacuum fluctuation of the bound modes with large angular momenta. This describes the interior of the black hole when the back reaction of the evaporation is considered. The black hole is a compact object with a surface (instead of horizon) that looks like a conventional black hole from the outside and eventually evaporates without a singularity. If we count the number of self-consistent configurations $\{|\psi ⟩\}$, we reproduce the area law of the entropy. This tells that the information is carried by the s-waves inside the black hole. $|\psi ⟩$ also describes the process that the negative ingoing energy flow created with Hawking radiation is superposed on the collapsing matter to decrease the total energy while the total energy density remains positive. As a special case, we consider conformal matter fields and show that the interior metric is determined by the matter content of the theory, which leads to a new constraint to the matter content.

    ↳ hep-thastro-ph.HEgr-qchep-phUniverse(2020)·24 citations
30. 30*

    Chiral Magnetic Effects in Nuclear Collisions

    Wei Li🇺🇸 · Gang Wang🇺🇸

    The interplay of quantum anomalies with strong magnetic field and vorticity in chiral systems could lead to novel transport phenomena, such as the chiral magnetic effect (CME), the chiral magnetic wave (CMW) and the chiral vortical effect (CVE). In high-energy nuclear collisions, these chiral effects may survive the expansion of a quark-gluon plasma fireball and be detected in experiments. The experimental searches for the CME, the CMW and the CVE, have aroused extensive interest over the past couple of decades. The main goal of this article is to review latest experimental progress in search for these novel chiral transport phenomena at Relativistic Heavy Ion Collider at BNL and the Large Hadron Collider at CERN. Future programs to help reduce uncertainties and facilitate the interpretation of the data are also discussed.

    ↳ nucl-exhep-exhep-phnucl-thAnn.Rev.Nucl.Part.Sci.(2020)·71 citations
31. 31*

    Entanglement and the Double Copy

    Clifford Cheung🇺🇸 · Grant N. Remmen🇺🇸

    We construct entangled states of gluons that scatter exactly as if they were gravitons. Operationally, these objects implement the double copy at the level of the wave function. Our analysis begins with a general ansatz for a wave function characterizing gluons in two copies of $\mathrm{SU}(N)$ gauge theory. Given relatively minimal assumptions following from permutation invariance and dimensional analysis, the three- and four-particle wave functions generate scattering amplitudes that automatically coincide exactly with gravity, modulo normalization. For five-particle scattering the match is not automatic but imposing certain known selection rules on the amplitude is sufficient to uniquely reproduce gravity. The resulting amplitudes exhibit a color-dressed and permutation-invariant form of the usual double copy relations. We compute the entanglement entropy between the two gauge theory copies and learn that these states are maximally-entangled at large $N$. Moreover, this approach extends immediately to effective field theories, where Born-Infeld photons and Galileons can be similarly recast as entangled gluons and pions.

    ↳ hep-thgr-qchep-phJHEP(2020)·11 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.