Fri·Mar 20, 2020Friday·March 20, 2020

1. 01*

   One-meson-loop NJL model: Effect of collective and noncollective excitations on the quark condensate at finite temperature

   Renan Câmara Pereira🇵🇹 · Pedro Costa🇵🇹

   We explore the effect of including quantum fluctuations in the two flavor Nambu$-$Jona-Lasinio model at finite temperature. This is accomplished, in a symmetry preserving way, by including collective and noncollective modes in the one-meson-loop gap equation which originate from poles and branch cuts in the complex plane, respectively. The inclusion of a boson cutoff, ${\Lambda }_b$, is necessary to regularize the meson-loop momenta. This new parameter is used to study the influence of going beyond the usual mean field approximation in the quark condensate. As the temperature increases, chiral symmetry tends to get restored, the collective modes melt and only noncollective modes contribute to the quark condensate. With the inclusion of such modes, the quark condensate at finite temperature has a different behavior than at mean field level that will be explored.

   hep-phnucl-thPRD(2020)·7 citations
2. 02*

   The left-right supersymmetric option at a high-energy upgrade of the LHC

   Mariana Frank🇨🇦 · Benjamin Fuks🇫🇷 · Katri Huitu🇫🇮 · Subhadeep Mondal🇫🇮 · Santosh Kumar Rai🇮🇳 · Harri Waltari🇬🇧

   We investigate the possibility that a minimal realization of left-right supersymmetry can be reachable at a high-energy upgrade of the LHC, expected to operate at a center-of-mass energy of 27 TeV. This minimal scenario has a relatively light $SU(2{)}_R$ doubly-charged Higgs boson, which could decay dominantly into tau-lepton pairs. We explore the associated signals comprised of at least three hadronically-decaying taus, or with at least two hadronic taus and one same-sign-same-flavor charged lepton pair. Our analysis shows that the former signature is challenging to use for getting handles on the signal due to the large corresponding background, and that the latter one can lead to a handful of new physics events in an almost background-free environment. We however find that a signal comprised of three hadronically-decaying tau leptons is likely to be observed at a low luminosity of proton-proton collisions at a 27 TeV upgrade of the LHC.

   hep-phPRD(2020)·6 citations
3. 03*

   Decay Properties of Conventional and Hybrid $B_c$ Mesons

   Nosheen Akbar🇵🇰

   Spectrum, radial wave functions at origin, decay constants, weak decay widths, life time and branching ratios for radially excited conventional and hybrid $B_c$ mesons are derived within non-relativistic quark model framework employing Schr$\ddot{\text{o}}$dinger equation by shooting method. Calculated results are compared with available theoretical results and experimental observations. This work may help in identifying the new discovered $B_c$ meson states at CDF ,LHCb and ATLAS.

   hep-ph2 citations
4. 04*

   Addendum to: Global constraints on absolute neutrino masses and their ordering

   Francesco Capozzi🇺🇸 · Eleonora Di Valentino🇫🇷 · Eligio Lisi🇮🇹 · Antonio Marrone🇮🇹 · Alessandro Melchiorri🇮🇹 · Antonio Palazzo🇮🇹

   We revisit our previous work [Phys. Rev. D 95, 096014 (2017)] where neutrino oscillation and nonoscillation data were analyzed in the standard framework with three neutrino families, in order to constrain their absolute masses and to probe their ordering (either normal, NO, or inverted, IO). We include updated oscillation results to discuss best fits and allowed ranges for the two squared mass differences $\delta m^2$ and $\Delta m^2$, the three mixing angles ${\theta }_{12}$, ${\theta }_{23}$ and ${\theta }_{13}$, as well as constraints on the CP-violating phase $\delta$, plus significant indications in favor of NO vs IO at the level of $\Delta {\chi }^2=10.0$. We then consider nonoscillation data from beta decay, from neutrinoless double beta decay (if neutrinos are Majorana), and from various cosmological input variants (in the data or the model) leading to results dubbed as default, aggressive, and conservative. In the default option, we obtain from nonoscillation data an extra contribution $\Delta {\chi }^2=2.2$ in favor of NO, and an upper bound on the sum of neutrino masses $\Sigma <0.15$ eV at $2\sigma$; both results - dominated by cosmology - can be strengthened or weakened by using more aggressive or conservative options, respectively. Taking into account such variations, we find that the combination of all (oscillation and nonoscillation) neutrino data favors NO at the level of $3.2-3.7\sigma$, and that $\Sigma$ is constrained at the $2\sigma$ level within $\Sigma <0.12-0.69$ eV. The upper edge of this allowed range corresponds to an effective $\beta$-decay neutrino mass $m_{\beta }=\Sigma /3=0.23$ eV, at the sensitivity frontier of the KATRIN experiment.

   hep-phastro-ph.COhep-exnucl-exPRD(2017)·509 citations
5. 05*

   Pair production of heavy charged gauge bosons in $pp$ collisions at LHC

   Ijaz Ahmed · Fazal Khaliq · M. U. Ashraf🇧🇪 · Taimoor Khurshid🇵🇰 · Jamil Muhammad🇰🇷

   Two opposite charged new heavy gauge boson pair production at the Large Hadron Collider (LHC) is presented in this paper. These bosons are known as $W^{{}^{\prime }}$ boson due to the reason that it is the heavy version of Standard Model's weak force carrier, the $W$ boson. The production cross section and decay width in proton-proton ($pp$) collision at \sqrts~= 8 TeV are calculated for different masses and coupling strengths of $W^{{}^{\prime }}$. Efficiencies for different signal regions and branching ratios for different decay channels are computed. In this study, the pair production ($W^{{}^{\prime +}}{W}^{{}^{\prime -}}$) is considered in emerging new physics as a result of $pp$ collision at \sqrts~= 8 TeV at the LHC with final state containing two tau ($\tau$) leptons and two neutrinos (each $W^{{}^{\prime }}$ decay to $\tau$ and its neutrino). The event selection efficiency similar to the CMS experiment is used for the mass of $W^{{}^{\prime }}$ to set lower limits for different coupling strengths of $W^{{}^{\prime }}$ and results are presented in this work. For heavy gauge bosons, when coupling strength is similar to that of Standard Model's $W$ boson, the mass of $W^{{}^{\prime }}$ below 305 GeV are excluded at confidence level of $95\%$.

   hep-phPhys.Scripta(2023)·1 citation
6. 06*

   Study of $b\to c$ induced ${\bar{B}}^{\ast }\to V\ell {\bar{\nu }}_{\ell }$ decays

   Qin Chang🇨🇳 · Xiao-Lin Wang🇨🇳 · Jie Zhu🇨🇳 · Xiao-Nan Li🇨🇳

   In this paper, we investigate the tree-dominated ${\bar{B}}_{u,d,s,c}^{\ast }\to V{\ell }^{-}{\bar{\nu }}_{\ell }$ ($V=D_{u,d}^{\ast },D_s^{\ast },J/\psi$ and $\ell =e,\mu ,\tau$) decays in the Standard Model with the relevant form factors obtained in the light-front quark model. These decays involve much more helicity states relative to the corresponding ${\bar{B}}^{\ast }\to P{\ell }^{-}{\bar{\nu }}_{\ell }$ and $\bar{B}\to V{\ell }^{-}{\bar{\nu }}_{\ell }$ decays, and moreover, the contribution of longitudinal polarization mode ($V$ meson) is relatively small, $\sim 30\%$, compared with the corresponding $B$ meson decays. We have also computed the branching fraction, lepton spin asymmetry, forward-backward asymmetry and ratio $R_V^{\ast (L)}\equiv \frac{\mathcal{B}({\bar{B}}^{\ast }\to V{\tau }^{-}{\bar{\nu }}_{\tau })}{\mathcal{B}({\bar{B}}^{\ast }\to V{\ell }^{\prime -}{\bar{\nu }}_{{\ell }^{\prime }})}$ (${\ell }^{\prime }=e,\mu$). Numerically, the branching fractions of ${\bar{B}}^{\ast }\to V{\ell }^{\prime -}{\bar{\nu }}_{{\ell }^{\prime }}$ decays are at the level of $\mathcal{O}(10^{-7})$, and are hopeful to be observed by LHC and Belle-II experiments. The ratios $R_{D^{\ast },D_s^{\ast },J/\psi }^{\ast (L)}$ have relatively small theoretical uncertainties and are close to each other, $R_{D^{\ast }}^{\ast (L)}\simeq R_{D_s^{\ast }}^{\ast (L)}\simeq R_{J/\psi }^{\ast (L)}\simeq [0.26,0.27]([0.27,0.29])$, which are a bit different from the predictions in some previous works. The future measurements are expected to make tests on these predictions.

   hep-phhep-exAdv.High Energy Phys.(2020)·8 citations
7. 07*

   Recasting direct detection limits within micrOMEGAs and implication for non-standard Dark Matter scenarios

   Genevieve Belanger🇫🇷 · Ali Mjallal🇫🇷 · Alexander Pukhov🇷🇺

   Direct detection experiments obtain 90% upper limits on the elastic scattering cross sections of dark matter with nucleons assuming point-like interactions and standard astrophysical and cosmological parameters. In this paper we provide a recasting of the limits from XENON1T, PICO-60, CRESST-III and DarkSide-50 and include them in micrOMEGAs. The code can then be used to directly impose constraints from these experiments on generic dark matter models under different assumptions about the DM velocity distribution or on the nucleus form factors. Moreover new limits on the elastic scattering cross sections can be obtained in the presence of a light t-channel mediator or of millicharged particles.

   hep-phEPJC(2021)·153 citations
8. 08*

   Dynamics of Nambu monopole in two Higgs doublet models -- Cosmological Monopole Collider --

   Minoru Eto🇯🇵 · Yu Hamada🇯🇵 · Masafumi Kurachi🇯🇵 · Muneto Nitta🇯🇵

   We study the dynamics of the Nambu monopole in two Higgs doublet models, which is a magnetic monopole attached by two topological $Z$ strings ($Z$ flux tubes) from two opposite sides. The monopole is a topologically stable solution of the equation of motions when the Higgs potential has global $U(1)$ and ${\mathbb{Z}}_2$ symmetries. In this paper, we consider more general cases without the ${\mathbb{Z}}_2$ symmetry, and find that it is no longer a static solution but moves along the $Z$ string being pulled by the heavier string. After analytically constructing an asymptotic form of the monopole, we confirm such a motion using the numerical relaxation method. In addition, we analyze the real time dynamics of the monopole based on a point-like approximation. Consequently, if there were long string networks with the monopoles in the early universe, the monopole accelerates nearly to the speed of light emitting electromagnetic radiations as a synchrotron accelerator, and collides to an anti-monopole on the string. This collision event, which we call the cosmological monopole collider, can produce much heavier particles than those we can see today, e.g., at the Large Hadron Collider.

   hep-phhep-thJHEP(2020)·26 citations
9. 09*

   Gravitational Wave Emissions from First Order Phase Transitions with Two Component FIMP Dark Matter

   Madhurima Pandey🇮🇳 · Avik Paul🇮🇳

   We explore the emissions of the Gravitational Waves (GWs) from a strong first-order ekectroweak phase transition. To this end, a dark matter model has been investigated in Feebly Interacting Massive Particle (FIMP) scenario, where the dark matter particles are produced through "freeze-in" mechanism in the early Universe and due to their very small couplings they could not attain thermal and chemical equilibrium with the Universe's thermal plasma. In this context, we extend scalar sector of Standard Model of particle physics by two additional scalar singlets whose stability is protected by an unbroken discrete $Z_2\times Z_2^{\prime }$ symmetry and they are assumed to develop no VEV after spontaneous symmetry breaking. We study the first-order phase transition within the framework of this present model. We have done both analytical and numerical computations to calculate the consequent production of GWs and then the detectabilities of such GWs have been investigated at the future space based detectors such as LISA, BBO, ALIA, DECIGO, aLIGO and aLIGO+ etc. We also find that dark matter self coupling has a considerable influence on the GW production in the present scenario.

   hep-ph10 citations
10. 10*

    Phase transition dynamics and gravitational wave spectra of strong first-order phase transition in supercooled universe

    Xiao Wang🇨🇳 · Fa Peng Huang🇺🇸 · Xinmin Zhang🇨🇳

    Phase transition dynamics may play important roles in the evolution history of the early universe, such as its possible roles in electroweak baryogenesis and dark matter.We systematically discuss and clarify the important details of the phase transition dynamics during a strong first-order phase transition (SFOPT). We classify the SFOPT into four types: slight supercooling, mild supercooling, strong supercooling, and ultra supercooling. Using different characteristic temperatures, length scales and bubble wall velocities, the corresponding gravitational wave (GW) spectra are investigated in details. We emphasize the essential importance of using the correct characteristic temperature and length scale when the phase transition dynamics and GW spectra are calculated. Especially, for strong supercooling and ultra supercooling cases, there are obvious differences of the phase transition strength and GW spectra between the results calculated at the nucleation temperature and those derived at the percolation temperature. For ultra supercooling case, we propose a criterion to quantify whether the phase transition can terminate. Besides the model-independent discussions, we also study three representative models as concrete examples to clearly show the subtle points therein.

    hep-phJCAP(2020)·134 citations
11. 11*

    A Minimal Model for Neutral Naturalness and pseudo-Nambu-Goldstone Dark Matter

    Aqeel Ahmed🇧🇪 · Saereh Najjari🇧🇪 · Christopher B. Verhaaren🇺🇸

    We outline a scenario where both the Higgs and a complex scalar dark matter candidate arise as the pseudo-Nambu-Goldstone bosons of breaking a global $SO(7)$ symmetry to $SO(6)$. The novelty of our construction is that the symmetry partners of the Standard Model top-quark are charged under a hidden color group and not the usual $SU(3{)}_c$. Consequently, the scale of spontaneous symmetry breaking and the masses of the top partners can be significantly lower than those with colored top partners. Taking these scales to be lower at once makes the model more natural and also reduces the induced non-derivative coupling between the Higgs and the dark matter. Indeed, natural realizations of this construction describe simple thermal WIMP dark matter which is stable under a global $U(1{)}_D$ symmetry. We show how the Large Hadron Collider along with current and next generation dark matter experiments will explore the most natural manifestations of this framework.

    hep-phJHEP(2020)·29 citations
12. 12*

    Dynamically assisted Schwinger mechanism and chirality production in parallel electromagnetic field

    Hidetoshi Taya🇨🇳

    We study particle and chirality production from the vacuum in the presence of a slow strong parallel electromagnetic field superimposed by a fast weak perturbative electromagnetic field. We derive an analytical formula for the particle and chirality production number based on the perturbation theory in the Furry picture. With the formula, we analytically discuss the interplay and dynamical assistance between the Schwinger mechanism and one-photon pair production and clarify effects of a parallel slow strong magnetic field. We also show that the dynamical assistance can significantly enhance chirality production, and that a sizable amount of chirality can be produced even for massive particles. Phenomenological applications including heavy-ion collisions and intense laser experiments are also discussed.

    hep-phhep-thnucl-thphysics.plasm-ph+1PRResearch(2020)·32 citations
13. 13*

    Chiral Symmetry and the Cosmological Constant

    Stephon Alexander🇺🇸 · Gabriel Herczeg🇺🇸 · Jinglong Liu🇺🇸 · Evan McDonough🇺🇸

    In this work we provide a link between a nearly vanishing cosmological constant and chiral symmetry. This is accomplished with a modification of General Relativity coupled to a topological field theory, namely BF theory by introducing fermions charged under the BF theory gauge group. We find that the cosmological constant sources a chiral anomaly for the fermions, providing a `technical naturalness' explanation for the smallness of the observed cosmological constant. Applied to the early universe, we show that production of fermions during inflation can provide all the dark matter in the universe today, in the form of superheavy dark baryons.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2020)·7 citations
14. 14*

    Model independent tests of the Kerr bound with extreme mass ratio inspirals

    Gabriel Andres Piovano🇮🇹 · Andrea Maselli🇮🇹 · Paolo Pani🇮🇹

    An outstanding prediction of general relativity is the fact that the angular momentum $S$ of an isolated black hole with mass $\mu$ is limited by the Kerr bound, $S\le G{\mu }^2/c$. Testing this cornerstone is challenging due to the difficulty in modelling spinning compact objects that violate this bound. We argue that precise, model-independent tests can be achieved by measuring gravitational waves from an extreme mass ratio inspiral around a supermassive object, one of the main targets of the future LISA mission. In the extreme mass ratio limit, the dynamics of the small compact object depends only on its multipole moments, which are free parameters. At variance with the comparable-mass case, accurate waveforms are valid also when the spin of the small object greatly exceeds the Kerr bound. By computing the orbital dephasing and the gravitational-wave signal emitted by a spinning point particle in circular, nonprecessing, equatorial motion around a Kerr black hole, we estimate that LISA will be able to measure the spin of the small compact object at the level of $10\%$. Together with mass measurements, this will allow for theory-agnostic, unprecedented constraints on string-theory inspired objects such as "superspinars", almost in their entire parameter space.

    ↳ gr-qcastro-ph.HEhep-phPLB(2020)·34 citations
15. 15*

    Complete flavor decomposition of the spin and momentum fraction of the proton using lattice QCD simulations at physical pion mass

    C. Alexandrou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · S. Bacchio (The Cyprus Inst.)🇨🇾 · M. Constantinou (Temple Univ.)🇺🇸 · J. Finkenrath (The Cyprus Inst.)🇨🇾 · K. Hadjiyiannakou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · G. Koutsou (The Cyprus Inst.)🇨🇾 · H. Panagopoulos (Univ. of Cyprus)🇨🇾 · G. Spanoudes (Univ. of Cyprus)🇨🇾

    We evaluate the gluon and quark contributions to the spin of the proton using an ensemble of gauge configuration generated at physical pion mass. We compute all valence and sea quark contributions to high accuracy. We perform a non-perturbative renormalization for both quark and gluon matrix elements. We find that the contribution of the up, down, strange and charm quarks to the proton intrinsic spin is $\frac{1}{2}{\sum }_{q=u,d,s,c}\Delta {\Sigma }^{q^{+}}=0.191(15)$ and to the total spin ${\sum }_{q=u,d,s,c}{J}^{q^{+}}=0.285(45)$. The gluon contribution to the spin is $J^g=0.187(46)$ yielding $J=J^q+J^g=0.473(71)$ confirming the spin sum. The momentum fraction carried by quarks in the proton is found to be $0.618(60)$ and by gluons $0.427(92)$, the sum of which gives $1.045(118)$ confirming the momentum sum rule. All scale and scheme dependent quantities are given in the $\overline{\mathrm{MS}}$ scheme at 2 GeV.

    ↳ hep-lathep-exhep-phnucl-ex+1PRD(2020)·191 citations
16. 16*

    Lattice QCD Inputs for Nuclear Double Beta Decay

    Vincenzo Cirigliano🇺🇸 · William Detmold🇺🇸 · Amy Nicholson🇺🇸 · Phiala Shanahan🇺🇸

    Second order beta-decay processes with and without neutrinos in the final state are key probes of nuclear physics and of the nature of neutrinos. Neutrinoful double-beta decay is the rarest Standard Model process that has been observed and provides a unique test of the understanding of weak nuclear interactions. Observation of neutrinoless double-beta decay would reveal that neutrinos are Majorana fermions and that lepton number conservation is violated in nature. While significant progress has been made in phenomenological approaches to understanding these processes, establishing a connection between these processes and the physics of the Standard Model and beyond is a critical task as it will provide input into the design and interpretation of future experiments. The strong-interaction contributions to double-beta decay processes are non-perturbative and can only be addressed systematically through a combination of lattice Quantum Chromoodynamics (LQCD) and nuclear many-body calculations. In this review, current efforts to establish the LQCD connection are discussed for both neutrinoful and neutrinoless double-beta decay. LQCD calculations of the hadronic contributions to the neutrinoful process $nn\to pp{e}^{-}{e}^{-}{\bar{\nu }}_e{\bar{\nu }}_e$ and to various neutrinoless pionic transitions are reviewed, and the connections of these calculations to the phenomenology of double-beta decay through the use of effective field theory (EFTs) is highlighted. At present, LQCD calculations are limited to small nuclear systems, and to pionic subsystems, and require matching to appropriate EFTs to have direct phenomenological impact. However, these calculations have already revealed qualitatively that there are terms in the EFTs that can only be constrained from double-beta decay processes themselves or using inputs from LQCD. Future prospects for direct calculations in larger nuclei are also discussed.

    ↳ nucl-thhep-lathep-phPPNP(2020)·40 citations
17. 17*

    Palatini quadratic gravity: spontaneous breaking of gauged scale symmetry and inflation

    D. M. Ghilencea🇷🇴

    We study quadratic gravity $R^2+R_{[\mu \nu ]}^2$ in the Palatini formalism where the connection and the metric are independent. This action has a {\it gauged} scale symmetry (also known as Weyl gauge symmetry) of Weyl gauge field $v_{\mu }=({\tilde{\Gamma }}_{\mu }-{\Gamma }_{\mu })/2$, with ${\tilde{\Gamma }}_{\mu }$ (${\Gamma }_{\mu }$) the trace of the Palatini (Levi-Civita) connection, respectively. The underlying geometry is non-metric due to the $R_{[\mu \nu ]}^2$ term acting as a gauge kinetic term for $v_{\mu }$. We show that this theory has an elegant spontaneous breaking of gauged scale symmetry and mass generation in the absence of matter, where the necessary scalar field ($\varphi$) is not added ad-hoc to this purpose but is "extracted" from the $R^2$ term. The gauge field becomes massive by absorbing the derivative term ${\partial }_{\mu }\ln \varphi$ of the Stueckelberg field ("dilaton"). In the broken phase one finds the Einstein-Proca action of $v_{\mu }$ of mass proportional to the Planck scale $M\sim ⟨\varphi ⟩$, and a positive cosmological constant. Below this scale $v_{\mu }$ decouples, the connection becomes Levi-Civita and metricity and Einstein gravity are recovered. These results remain valid in the presence of non-minimally coupled scalar field (Higgs-like) with Palatini connection and the potential is computed. In this case the theory gives successful inflation and a specific prediction for the tensor-to-scalar ratio $0.007\le r\le 0.01$ for current spectral index $n_s$ (at $95\%$CL) and N=60 efolds. This value of $r$ is mildly larger than in inflation in Weyl quadratic gravity of similar symmetry, due to different non-metricity. This establishes a connection between non-metricity and inflation predictions and enables us to test such theories by future CMB experiments.

    ↳ hep-thastro-ph.COgr-qchep-phEPJC·76 citations
18. 18*

    Study of proton parton distribution functions at high x using ZEUS data

    ZEUS Collaboration

    At large values of x the parton distribution functions (PDFs) of the proton are poorly constrained and there are considerable variations between different global fits. Data at such high x have already been published by the ZEUS Collaboration, but not yet used in PDF extractions. A technique for comparing predictions based on different PDF sets to the observed number of events in the ZEUS data is presented. It is applied to compare predictions from the most commonly used PDFs to published ZEUS data at high Bjorken x. A wide variation is found in the ability of the PDFs to predict the observed results. A scheme for including the ZEUS high-x data in future PDF extractions is discussed.

    ↳ hep-exhep-phPRD(2020)·20 citations
19. 19*

    New, multipole solutions of relativistic, viscous hydrodynamics

    T. Csorgo🇭🇺 · G. Kasza🇭🇺

    We present a new class of exact fireball solutions of relativistic dissipative hydrodynamics. We describe new exact solutions both for the relativistic Navier-Stokes and for the Israel-Stewart theory, for arbitrary shear and bulk viscosities, as well as for other dissipative coefficients. The common property of these solutions is the presence of the relativistic Hubble flow. Our results generalize the recently found first solution in these classes, for an arbitrary temperature dependent speed of sound, shear and bulk viscosity, heat conduction and fluctuating initial temperature profiles. These solutions are causal and not only stable but also asymptotically perfect. A strong and narrow peak in the kinematic bulk viscosity is shown to imitate the effects of a first order phase transition. The new class of asymptotically perfect solutions is thus found to be very rich, but at the same time mostly academic as the solutions are limited by the spherical symmetry of the Hubble flow field.

    ↳ nucl-thhep-phGribov-90 Memorial Volume, pp. 297-318 (2…·8 citations
20. 20*

    Towards a Computer Vision Particle Flow

    Francesco Armando Di Bello🇮🇹 · Sanmay Ganguly🇮🇱 · Eilam Gross🇮🇱 · Marumi Kado🇮🇹 · Michael Pitt🇨🇭 · Lorenzo Santi🇮🇹 · Jonathan Shlomi🇮🇱

    In High Energy Physics experiments Particle Flow (PFlow) algorithms are designed to provide an optimal reconstruction of the nature and kinematic properties of the particles produced within the detector acceptance during collisions. At the heart of PFlow algorithms is the ability to distinguish the calorimeter energy deposits of neutral particles from those of charged particles, using the complementary measurements of charged particle tracking devices, to provide a superior measurement of the particle content and kinematics. In this paper, a computer vision approach to this fundamental aspect of PFlow algorithms, based on calorimeter images, is proposed. A comparative study of the state of the art deep learning techniques is performed. A significantly improved reconstruction of the neutral particle calorimeter energy deposits is obtained in a context of large overlaps with the deposits from charged particles. Calorimeter images with augmented finer granularity are also obtained using super-resolution techniques.

    ↳ physics.data-anhep-exhep-phphysics.ins-det+1EPJC(2021)·53 citations
21. 21*

    Observation of gauge invariance in a 71-site Bose-Hubbard quantum simulator

    Bing Yang🇨🇳 · Hui Sun🇨🇳 · Robert Ott🇩🇪 · Han-Yi Wang🇨🇳 · Torsten V. Zache🇩🇪 · Jad C. Halimeh🇮🇹 · Zhen-Sheng Yuan🇨🇳 · Philipp Hauke🇩🇪 · Jian-Wei Pan🇨🇳

    The modern description of elementary particles, as formulated in the Standard Model of particle physics, is built on gauge theories. Gauge theories implement fundamental laws of physics by local symmetry constraints. For example, in quantum electrodynamics, Gauss's law introduces an intrinsic local relation between charged matter and electromagnetic fields, which protects many salient physical properties including massless photons and a long-ranged Coulomb law. Solving gauge theories by classical computers is an extremely arduous task, which has stimulated a vigorous effort to simulate gauge-theory dynamics in microscopically engineered quantum devices. Previous achievements implemented density-dependent Peierls phases without defining a local symmetry, realized mappings onto effective models to integrate out either matter or electric fields, or were limited to very small systems. The essential gauge symmetry has not been observed experimentally. Here, we report the quantum simulation of an extended U(1) lattice gauge theory, and experimentally quantify the gauge invariance in a many-body system comprising matter and gauge fields. These are realized in defect-free arrays of bosonic atoms in an optical superlattice of 71 sites. We demonstrate full tunability of the model parameters and benchmark the matter--gauge interactions by sweeping across a quantum phase transition. Enabled by high-fidelity manipulation techniques, we measure the degree to which Gauss's law is violated by extracting probabilities of locally gauge-invariant states from correlated atom occupations. Our work provides a way to explore gauge symmetry in the interplay of fundamental particles using controllable large-scale quantum simulators.

    ↳ cond-mat.quant-gashep-lathep-phphysics.atom-ph+1Nature(2020)·428 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.