Thu·Oct 15, 2020Thursday·October 15, 2020

1. 01*

   Renormalon Effects in Quasi Parton Distributions

   Wei-Yang Liu🇹🇼 · Jiunn-Wei Chen🇹🇼

   We investigate the renormalon ambiguity from bubble-chain diagrams in the isovector unpolarized quasi-parton distribution function (PDF) of a hadron. We confirm the assertion by Braun, Vladimirov and Zhang (arXiv:1810.00048) that the leading IR renormalon ambiguity is formally an $\mathcal{O}({\Lambda }_{QCD}^2/x^2{P}_z^2)$ effect, with $x$ the parton momentum fraction and $P_z$ the hadron momentum, together with a new $\mathcal{O}(\delta (x){\Lambda }_{QCD}^2/P_z^2)$ contribution such that the quark number is conserved. This implies the convergence of the perturbative matching kernel between a quasi-PDF and a PDF would eventually fail for small $x$. However, in both the R-scheme designed to cancel the leading IR renormalon and the typically used RI/MOM scheme in lattice QCD for the same quasi-PDF, we find good convergence in the kernel based on three-loop bubble-chain diagram analyses. These results are encouraging for the quasi-PDF program. However, firm conclusions can only be drawn after the complete higher loop QCD calculations are carried out.

   hep-phPRD(2021)·25 citations
2. 02*

   Mass structure of hadrons and light-front sum rules in t' Hooft model

   Xiangdong Ji🇺🇸 · Yizhuang Liu🇨🇳 · Ismail Zahed🇺🇸

   We study the mass/energy structure of the bound state of hadrons in two-dimensional quantum chromodynamics in the large number of color limit (t' Hooft model). We analyze separately the contributions from the traceless and trace part of the energy-momentum tensor, and show that the masses are related to the matrix elements of the scalar charge and Coulomb energy. We derive the light-front sum rules for the scalar charge and Coulomb energy, expressed in terms of the light-front wave functions, and find that they are regular at $x=0$ without the delta function contribution. We also consider the result for the massless Goldstone boson, as well as the structure of the gravitational form factors of the bound meson states.

   hep-phhep-lathep-thnucl-thPRD(2021)·23 citations
3. 03*

   Three-particle fields as a method of description of baryons in the scattering processes

   O.S. Potiienko · I.V. Sharph · T.M. Zelentsova · N.O. Chudak · G.G. Neboga · K.K. Merkotan · D.A. Ptashynskiy

   In this paper we propose a model within which the keeping of quarks inside a proton and the interaction of these quarks with quarks of another hadron can be described simultaneously. The model of a three-particle bispinor field is used for this purpose. Such a field, in comparison with the usual one-particle field, is considered not on Minkowski space, but on a subset of the tensor product of three Minkowski spaces, which is characterized by the equality of time coordinates of three events (subset of simultaneity). Such a subset cannot be distinguished by the Lorentz invariant method. But due to the multiparticle field transformation law in the transition from one inertial system to another one, the dynamic equations for a three-particle field are consistent with the principle of relativity. The interaction between quarks is introduced by requiring a local SUc(3) invariance. But in the paper a more general way to achieve this invariance than the replacement in Lagrangian of ordinary derivatives by covariance is proposed. The applied procedure leads to a two-index tensor of gauge field, both for Lorentz and internal indices. The connection of this field with the bound states of gluons - glueballs is discussed. It is shown that this glueball field can be represented as the sum of two terms: the classical field, which plays the role of the potential energy of quark interaction in the proton, and the field corresponding to quantum fluctuations around the classical field and describes the quark interaction in proton with other hadrons. A dynamic equation is obtained for the field that determines the potential energy of quark interaction. It is shown that this equation has solutions that correspond to the confinement of quarks.

   hep-phUkr.J.Phys.(2024)·1 citation
4. 04*

   Four-lepton Z-boson decay constraints on the SMEFT

   Radja Boughezal🇺🇸 · Chien-Yi Chen🇺🇸 · Frank Petriello🇺🇸 · Daniel Wiegand🇺🇸

   We discuss how four-lepton decays of the Z-boson probe currently unconstrained flat directions in the parameter space of the Standard Model Effective Field Theory (SMEFT). We derive the constraints from these decays on four-lepton operators in the SMEFT and show how the LHC data for this process complements probes from neutrino-trident production. Future differential measurements with high-luminosity data can strongly constrain four-lepton operators and remove all flat directions in the four-muon sector of the SMEFT. We comment briefly on the possibility of using rare Z-decays to tau-leptons to probe untested directions in the SMEFT parameter space.

   hep-phPRD(2021)·13 citations
5. 05*

   Hybrid Stars with Hyperons and Strange Quark Matter

   Wasif Husain🇦🇺 · Anthony W. Thomas🇦🇺

   We consider the possibility of having hybrid stars with a phase transition from hadrons into strange matter at the core of a neutron star in b equilibrium. For the hadron phase equation of state (EoS) the quark-meson coupling model is used, while the MIT bag model is used to describe the strange matter phase. The phase transition is treated using the Gibbs construction method and results are calculated and checked against the observational constaints imposed on the EoS. The results are also compared with the hadronic EoS including hyperons, F-QMC700

   hep-phastro-ph.HEnucl-thAIP Conf.Proc.(2021)·11 citations
6. 06*

   Perturbative method to estimate meson masses in the framework of Bethe-Salpeter equation beyond its dominant interaction

   Shu-Sheng Xu🇨🇳 · Chao Shi🇨🇳

   We propose a novel method to calculate the meson mass in the framework of Dyson-Schwinger equation and Bethe-Salpeter equation, once their dominant interactions are identified. The method is based on the perturbation theory of matrix, which is widely used in quantum mechanics. Taking interactions other than the dominant ones as perturbations, we derive the first order correction of quark propagator. Implementing the perturbation on BSE, the mass correction at first order is then given. We exemplify this method with the well known Rainbow-Ladder (RL) truncation, and go beyond the RL using a simple model, i.e., the Munczek-Nemirovsky~(MN) model, by studying the pion and $\rho$ mesons mass shift. The results are all in good agreement with those obtained by fully solving the BSE beyond RL. Our perturbative method therefore can be used to give a semi-quantitative estimate of meson mass correction in cases when the BSEs are complicated by interactions that go beyond the dominant one.

   hep-phPRD(2020)·0 citations
7. 07*

   A Model of Interacting Dark Matter and Dark Radiation for $H_0$ and ${\sigma }_8$ Tensions

   Gongjun Choi🇨🇳 · Tsutomu T. Yanagida🇨🇳 · Norimi Yokozaki🇯🇵

   We present a model describing the dark sector (DS) featured by two interactions remaining efficient until late times in the matter-dominated era after recombination: the interaction among dark radiations (DR), and the interaction between a small fraction of dark matter and dark radiation. The dark sector consists of (1) a dominant component cold collisionless DM (DM1), (2) a sub-dominant cold DM (DM2) and (3) a self-interacting DR. When a sufficient amount of DR is ensured and a few percent of the total DM density is contributed by DM2 interacting with DR, this set-up is known to be able to resolve both the Hubble and ${\sigma }_8$ tension. In light of this, we propose a scenario which is logically natural and has an intriguing theoretical structure with a hidden unbroken gauge group $\mathrm{SU}(5{)}_{\mathrm{X}}\otimes \mathrm{U}(1{)}_{\mathrm{X}}$. Our model of the dark sector does not introduce any new scalar field, but contains only massless chiral fermions and gauge fields in the ultraviolet (UV) regime. As such, it introduces a new scale (DM2 mass, $m_{DM2}$) based on the confinement resulting from the strong dynamics of $\mathrm{SU}(5{)}_{\mathrm{X}}$. Both DM2-DR and DR-DR interactions are attributed to an identical long range interaction of $\mathrm{U}(1{)}_{\mathrm{X}}$. We show that our model can address the cosmological tensions when it is characterized by $g_{\mathrm{X}}=\mathcal{O}(10^{-3})-\mathcal{O}(10^{-2})$, $m_{DM2}=\mathcal{O}(1)-\mathcal{O}(100)\mathrm{GeV}$ and $T_{\mathrm{DS}}/T_{\mathrm{SM}}\simeq 0.3-0.4$ where $g_{\mathrm{X}}$ is the gauge coupling of $\mathrm{U}(1{)}_{\mathrm{X}}$ and $T_{\mathrm{DS}}$ ($T_{\mathrm{SM}}$) is a temperature of the DS (Standard Model sector). Our model explains candidates of DM2 and DR, and DM1 can be any kind of CDM.

   hep-phJHEP(2021)·26 citations
8. 08*

   Resummation methods for Master Integrals

   Dhimiter D. Canko🇬🇷 · Nikolaos Syrrakos🇬🇷

   We present in detail two resummation methods emerging from the application of the Simplified Differential Equations approach to a canonical basis of master integrals. The first one is a method which allows for an easy determination of the boundary conditions, since it finds relations between the boundaries of the basis elements and the second one indicates how using the $x\to 1$ limit to the solutions of a canonical basis, one can obtain the solutions to a canonical basis for the same problem with one mass less. Both methods utilise the residue matrices for the letters $\{0,1\}$ of the canonical differential equation. As proof of concept, we apply these methods to a canonical basis for the three-loop ladder-box with one external mass off-shell, obtaining subsequently a canonical basis for the massless three-loop ladder-box as well as its solution.

   hep-phhep-thJHEP(2021)·20 citations
9. 09*

   NLO QCD predictions for doubly-polarized WZ production at the LHC

   Ansgar Denner🇩🇪 · Giovanni Pelliccioli🇩🇪

   Accessing the polarization of weak bosons provides an important probe for the mechanism of electroweak symmetry breaking. Relying on the double-pole approximation and on the separation of polarizations at the amplitude level, we study WZ production at the LHC, with both bosons in a definite polarization mode, including NLO QCD effects. We compare results obtained defining the polarization vectors in two different frames. Integrated and differential cross-sections in a realistic fiducial region are presented.

   hep-phhep-exPLB(2021)·62 citations
10. 10*

    The semi-leptonic form factors of ${\Lambda }_b\to {\Lambda }_c$ and ${\Xi }_b\to {\Xi }_c$ in QCD sum rules

    Zhen-Xing Zhao🇨🇳 · Run-Hui Li🇨🇳 · Yue-Long Shen🇨🇳 · Yu-Ji Shi🇩🇪 · Yan-Sheng Yang🇨🇳

    In this work, the full leading order results of the form factors for ${\Xi }_b\to {\Xi }_c$ and ${\Lambda }_b\to {\Lambda }_c$ are obtained in QCD sum rules. Contributions from up to dim-5 have been considered. For completeness, we also study the two-point correlation function to obtain the pole residues of ${\Xi }_Q$ and ${\Lambda }_Q$, and higher accuracy is achieved. For the three-point correlation function, since stable Borel regions can not be found, about $20\%$ uncertainties are introduced for the form factors of ${\Xi }_b\to {\Xi }_c$ and ${\Lambda }_b\to {\Lambda }_c$. Our results for the form factors are consistent with those of the Lattice QCD within errors.

    hep-phEPJC(2020)·44 citations
11. 11*

    Detecting Composite Dark Matter with Long Range and Contact Interactions in Gas Clouds

    Amit Bhoonah🇨🇦 · Joseph Bramante🇨🇦 · Sarah Schon🇨🇦 · Ningqiang Song🇨🇦

    Cold interstellar gas clouds provide an exciting new method to discover dark matter. Their immense size makes them uniquely sensitive to interactions from the heaviest, most rarefied dark matter models. Using gas cloud observations, we derive constraints on heavy composite dark matter coupled to the Standard Model through a light dark photon for dark matter up to a thousand solar masses. We find gas clouds are also sensitive to very large composite dark matter that interacts with nuclei through a fixed contact interaction cross section. We also study the contact interaction model and implement multiscatter and overburden analyses to obtain bounds from experiments like CDMS, CRESST, DAMA, XQC, and XENON1T.

    hep-phastro-ph.GAPRD(2021)·49 citations
12. 12*

    Standard Model $\mathcal{O}(\alpha )$ renormalization of $g_A$ and its impact on new physics searches

    Leendert Hayen🇺🇸

    We present an $\mathcal{O}(\alpha )$ Standard Model calculation of the inner radiative corrections to Gamow-Teller $\beta$ decays. We find that \textit{a priori} contributions arise from the photonic vertex correction and $\gamma W$ box diagram. Upon evaluation most elastic contributions vanish due to crossing symmetry or cancellation between isoscalar and isovector photonic contributions, leaving only the polarized parity-odd contribution, i.e., the Gamow-Teller equivalent of the well-known axial $\gamma W$ box contribution for Fermi decays. We show that weak magnetism contributes significantly to the Born amplitude, and consider additional hadronic contributions at low energy using a holomorphic continuation of the polarized Bjorken sum rule constrained by experimental data. We perform the same procedure for the Fermi inner radiative correction through a combination of the running of Bjorken and Gross-Llewellyn Smith sum rules. We discuss heavy flavor, higher-twist, and target mass corrections and find a significant increase at low momentum from the latter. We find ${\Delta }_R^A=0.02532(22)$ and ${\Delta }_R^V=0.02473(27)$ for axial and vector inner radiative corrections, respectively, resulting in ${\Delta }_R^A-{\Delta }_R^V=0.60(5)\times 10^{-3}$, which allows us to extract $g_A^0$ for the first time to our knowledge. We discuss consequences for comparing experimental data to lattice calculations in beyond Standard Model fits. Further, we show how some traditional $\beta$ decay calculations contain part of this effect but fail to account for cancellations in the full $\mathcal{O}(\alpha )$result. Finally, we correct for a double-counting instance in the isospin $T=1/2$ mirror decay extraction of $|V_{ud}|$, the up-down matrix element of the Cabibbo-Kobayashi-Maskawa matrix, resolving a long-standing tension and leading to increased precision.

    hep-phhep-latnucl-exnucl-thPRD(2021)·113 citations
13. 13*

    Long-lived Sterile Neutrinos at the LHC in Effective Field Theory

    Jordy de Vries🇺🇸 · Herbert K. Dreiner🇩🇪 · Julian Y. Günther🇩🇪 · Zeren Simon Wang🇰🇷 · Guanghui Zhou🇺🇸

    We study the prospects of a displaced-vertex search of sterile neutrinos at the Large Hadron Collider (LHC) in the framework of the neutrino-extended Standard Model Effective Field Theory ($\nu$SMEFT). The production and decay of sterile neutrinos can proceed via the standard active-sterile neutrino mixing in the weak current, as well as through higher-dimensional operators arising from decoupled new physics. If sterile neutrinos are long-lived, their decay can lead to displaced vertices which can be reconstructed. We investigate the search sensitivities for the ATLAS/CMS detector, the future far-detector experiments: AL3X, ANUBIS, CODEX-b, FASER, MATHUSLA, and MoEDAL-MAPP, and at the proposed fixed-target experiment SHiP. We study scenarios where sterile neutrinos are predominantly produced via rare charm and bottom mesons decays through minimal mixing and/or dimension-six operators in the $\nu$SMEFT Lagrangian. We perform simulations to determine the potential reach of high-luminosity LHC experiments in probing the EFT operators, finding that these experiments are very competitive with other searches.

    hep-phJHEP(2021)·104 citations
14. 14*

    Mass-suppressed effects in heavy quark diffusion

    A. Bouttefeux🇨🇭 · M. Laine🇨🇭

    Many lattice studies of heavy quark diffusion originate from a colour-electric correlator, obtained as a leading term after an expansion in the inverse of the heavy-quark mass. In view of the fact that the charm quark is not particularly heavy, we consider subleading terms in the expansion. Working out correlators up to $O(1/M^2)$, we argue that the leading corrections are suppressed by $O(T/M)$, and one of them can be extracted from a colour-magnetic correlator. The corresponding transport coefficient is non-perturbative already at leading order in the weak-coupling expansion, and therefore requires a non-perturbative determination.

    hep-phhep-latJHEP(2020)·35 citations
15. 15*

    String (gravi)photons, "dark brane photons", holography and the hypercharge portal

    Pascal Anastasopoulos (Vienna U.)🇦🇹 · Massimo Bianchi (Rome U., Tor Vergata and INFN, Rome2)🇮🇹 · Dario Consoli (Vienna U.)🇦🇹 · Elias Kiritsis (Crete U. and APC, Paris)🇬🇷

    The mixing of graviphotons and dark brane photons to the Standard Model hypercharge is analyzed in full generality, in weakly-coupled string theory. Both the direct mixing as well as effective terms that provide mixing after inclusion of SM corrections are estimated to lowest order. The results are compared with Effective Field Theory (EFT) couplings, originating in a hidden large-N theory coupled to the SM. The string theory mixing terms are typically subleading compared with the generic EFT couplings. The case where the hidden theory is a holographic theory is also analyzed, providing also suppressed mixing terms to the SM hypercharge.

    hep-phhep-thFortsch.Phys.(2021)·16 citations
16. 16*

    Improved limits for violations of local position invariance from atomic clock comparisons

    R. Lange🇩🇪 · N. Huntemann🇩🇪 · J. M. Rahm🇩🇪 · C. Sanner🇩🇪 · H. Shao🇩🇪 · B. Lipphardt🇩🇪 · Chr. Tamm🇩🇪 · S. Weyers🇩🇪 · E. Peik🇩🇪

    We compare two optical clocks based on the ${}^2$S${}_{1/2}(F=0)\to {}^2$D${}_{3/2}(F=2)$ electric quadrupole (E2) and the ${}^2$S${}_{1/2}(F=0)\to {}^2$F${}_{7/2}(F=3)$ electric octupole (E3) transition of ${}^{171}$Yb${}^{+}$ and measure the frequency ratio ${\nu }_{E3}/{\nu }_{E2}=0.932829404530965376(32)$. We determine the transition frequency ${\nu }_{E3}=642121496772645.10(8)$ Hz using two caesium fountain clocks. Repeated measurements of both quantities over several years are analyzed for potential violations of local position invariance. We improve by factors of about 20 and 2 the limits for fractional temporal variations of the fine structure constant $\alpha$ to $1.0(1.1)\times 10^{-18}/\mathrm{yr}$ and of the proton-to-electron mass ratio $\mu$ to $-8(36)\times 10^{-18}/\mathrm{yr}$. Using the annual variation of the Sun's gravitational potential at Earth $\Phi$, we improve limits for a potential coupling of both constants to gravity, $(c^2/\alpha )(d\alpha /d\Phi )=14(11)\times 10^{-9}$ and $(c^2/\mu )(d\mu /d\Phi )=7(45)\times 10^{-8}$.

    ↳ physics.atom-phgr-qchep-phquant-phPRL(2021)·158 citations
17. 17*

    Finite density effects on chiral symmetry breaking in a magnetic field in 2+1 dimensions from holography

    Diego M. Rodrigues🇧🇷 · Danning Li🇨🇳 · Eduardo Folco Capossoli🇧🇷 · Henrique Boschi-Filho🇧🇷

    In this work we study finite density effects in spontaneous chiral symmetry breaking as well as chiral phase transition under the influence of a background magnetic field in $2+1$ dimensions. For this purpose, we use an improved holographic softwall model based on an interpolated dilaton profile. We find inverse magnetic catalysis at finite density. We observe that the chiral condensate decreases as the density increases, and the two effects (addition of magnetic field and chemical potential) sum up decreasing even more the chiral condensate.

    ↳ hep-thhep-phPRD(2021)·16 citations
18. 18*

    Studies of Quantum-Mechanical Coherency Effects in Neutrino-Nucleus Elastic Scattering

    V. Sharma🇹🇼 · L. Singh🇹🇼 · H.T. Wong🇹🇼 · M. Agartioglu🇹🇼 · J.-W. Chen🇹🇼 · M. Deniz🇹🇷 · S. Kerman🇹🇷 · H.B Li🇹🇼 · C.-P. Liu🇹🇼 · K. Saraswat🇹🇼 · M.K. Singh🇹🇼 · V. Singh (TEXONO Collaboration)🇮🇳

    Neutrino-nucleus elastic scattering ($\nu {\mathrm{A}}_{el}$) provides a unique laboratory to study the quantum-mechanical (QM) coherency effects in electroweak interactions. The deviations of the cross-sections from those of completely coherent systems can be quantitatively characterized through a coherency parameter $\alpha (q^2)$. The relations between $\alpha$ and the underlying nuclear physics in terms of nuclear form factors are derived. The dependence of cross-section on $\alpha (q^2)$ for the various neutrino sources is presented. The $\alpha (q^2)$-values are evaluated from the measured data of the COHERENT CsI and Ar experiments. Complete coherency and decoherency conditions are excluded by the CsI data with $p=0.004$ at $q^2=3.1\times 10^3\mathrm{Me}{\mathrm{V}}^2$ and with $p=0.016$ at $q^2=2.3\times 10^3\mathrm{Me}{\mathrm{V}}^2$, respectively, verifying that both QM superpositions and nuclear many-body effects contribute to $\nu {\mathrm{A}}_{el}$ interactions.

    ↳ hep-exhep-phnucl-exPRD(2021)·20 citations
19. 19*

    Module Intersection for the Integration-by-Parts Reduction of Multi-Loop Feynman Integrals

    Dominik Bendle🇩🇪 · Janko Boehm🇩🇪 · Wolfram Decker🇩🇪 · Alessandro Georgoudis🇫🇷 · Franz-Josef Pfreundt🇩🇪 · Mirko Rahn🇩🇪 · Yang Zhang🇨🇳

    In this manuscript, which is to appear in the proceedings of the conference "MathemAmplitude 2019" in Padova, Italy, we provide an overview of the module intersection method for the the integration-by-parts (IBP) reduction of multi-loop Feynman integrals. The module intersection method, based on computational algebraic geometry, is a highly efficient way of getting IBP relations without double propagator or with a bound on the highest propagator degree. In this manner, trimmed IBP systems which are much shorter than the traditional ones can be obtained. We apply the modern, Petri net based, workflow management system GPI-Space in combination with the computer algebra system Singular to solve the trimmed IBP system via interpolation and efficient parallelization. We show, in particular, how to use the new plugin feature of GPI-Space to manage a global state of the computation and to efficiently handle mutable data. Moreover, a Mathematica interface to generate IBPs with restricted propagator degree, which is based on module intersection, is presented in this review.

    ↳ hep-thhep-phPoS(2022)·28 citations
20. 20*

    ${\Lambda }_{c}N$ interaction in leading order covariant chiral effective field theory

    Jing Song🇨🇳 · Yang Xiao🇨🇳 · Zhi-Wei Liu🇨🇳 · Chun-Xuan Wang🇨🇳 · Kai-Wen Li🇨🇳 · Li-Sheng Geng🇨🇳

    We study the ${\Lambda }_{c}N$ interaction in the covariant chiral effective field theory (ChEFT) at leading order. All the relevant low-energy constants are determined by fitting to the lattice QCD simulations from the HAL QCD Collaboration. Extrapolating the results to the physical point, we show that the ${\Lambda }_{c}N$ interaction is weakly attractive in the ${}^1{S}_0$ channel, but in the ${}^3{S}_1$ channel, it is only attractive at extremely low energies and soon turns repulsive for larger laboratory energy. Furthermore, we show that the neglect of the ${}^3{S}_1-{}^3{D}_1$ coupling provided by the leading order covariant ChEFT would result in an attractive interaction in the ${}^3{S}_1$ channel at the physical point, which coincides with the previous non-relatistic ChEFT study. As a byproduct, we predict the ${}^3{D}_1$ phase shifts and the mixing angel ${\epsilon }_1$, which can be checked by future lattice QCD simulations. In addition, we compare the ${\Lambda }_{c}N$ interaction with the $\Lambda N$ and $NN$ interactions to study how the baryon-nucleon ($BN$) interactions evolve as a function of the baryon mass with the replacement of a light quark by a strange or charm quark in the baryon ($B$).

    ↳ nucl-thhep-phPRC(2020)·16 citations
21. 21*

    Hadrons and Few-Body Physics

    Jean-Marc Richard🇫🇷

    We present a selection of topics with an interplay of hadron and few-body physics. This includes few-nucleon systems, light hypernuclei and quark dynamics for baryons and multiquarks. It is stressed that standard quark models predict very few stable multiquarks.

    ↳ nucl-thhep-phFew Body Syst.(2020)·3 citations
22. 22*

    Targeted Likelihood-Free Inference of Dark Matter Substructure in Strongly-Lensed Galaxies

    Adam Coogan🇳🇱 · Konstantin Karchev🇳🇱 · Christoph Weniger🇳🇱

    The analysis of optical images of galaxy-galaxy strong gravitational lensing systems can provide important information about the distribution of dark matter at small scales. However, the modeling and statistical analysis of these images is extraordinarily complex, bringing together source image and main lens reconstruction, hyper-parameter optimization, and the marginalization over small-scale structure realizations. We present here a new analysis pipeline that tackles these diverse challenges by bringing together many recent machine learning developments in one coherent approach, including variational inference, Gaussian processes, differentiable probabilistic programming, and neural likelihood-to-evidence ratio estimation. Our pipeline enables: (a) fast reconstruction of the source image and lens mass distribution, (b) variational estimation of uncertainties, (c) efficient optimization of source regularization and other hyperparameters, and (d) marginalization over stochastic model components like the distribution of substructure. We present here preliminary results that demonstrate the validity of our approach.

    ↳ astro-ph.COastro-ph.GAastro-ph.IMhep-ph35 citations
23. 23*

    P-stars in the gravitational wave era

    Paolo Cea🇮🇹

    P-stars are compact relativistic stars made of deconfined up and down quarks in a chromomagnetic condensate proposed by us long time ago. P-stars do not admit a critical mass thereby they are able to overcome the gravitational collapse to black holes. In this work we discuss in greater details our theoretical proposal for P-stars. We point out that our theory for compact relativistic stars stems from our own understanding of the confining quantum vacuum supported by estensive non-perturbative numerical simulations of Quantum ChromoDynamics on the lattice. We compare our proposal with the constraints arising from the recent observations of massive pulsars, the gravitational event GW170817 and the precise determination of the PSR J0030+0451 mass and radius from NICER data. We argue that core-collapsed supernovae could give rise to a P-star instead of a neutron star. In this case we show that the birth of a P-star could solve the supernova explosion problem leading to successful supernova explosions with total energies up to $10^{53}$ erg. We critically compare P-stars with the gravitational wave event GW170817 and the subsequent electromagnetic follow-up, the short Gamma Ray Burst GRB170817A and the kilonova AT2017gfo. We also present an explorative study on gravitational wave emission from coalescing binary P-stars with masses $M_1\simeq M_2\simeq 30M_{\odot }$. We attempt a qualitative comparison with the gravitational wave event GW150914. We find that the gravitational wave strain amplitude from massive P-star binaries could mimic the ringdown gravitational wave emission by coalescing black hole binaries. We point out that a clear signature for massive P-stars would be the detection of wobble frequencies in the gravitational wave strain amplitude in the post-merger phase of two coalescing massive compact objects with unequal masses.

    ↳ astro-ph.HEgr-qchep-phEur.Phys.J.Plus(2020)·0 citations
24. 24*

    Chiral kinetic theory of anomalous transport induced by torsion

    Lan-Lan Gao🇨🇳 · Sahal Kaushik🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Evan John Philip🇺🇸

    In Weyl semimetals subjected to torsion, there are two different kinds of chirality: i) the (coordinate-space) shape of the twisted crystal is chiral, and ii) the momentum space contains chiral quasi-particles. Here we construct a general kinetic theory of anomalous transport using the phase space (coordinate and momentum spaces combined) Berry curvature induced by torsion in Weyl systems. We describe how torsion generates the chiral chemical potential, and thus leads to the Chiral Magnetic Effect (CME) in the presence of a background magnetic field. We propose to measure the CME current induced by the torsion as a way to detect the anomalous coupling between the coordinate-space and momentum-space chiralities.

    ↳ cond-mat.mes-hallhep-phPRB(2021)·17 citations
25. 25*

    Fundamental physical constants at low and high redshifts

    S. A. Levshakov🇷🇺

    Spacetime variations of physical constants can be associated with the existence of Higgs-like scalar field(s) that couple non-universally to the baryonic matter. Recent results of astronomical spectral measurements of the fractional changes in the electron-to-proton mass ratio, mu = m_e/m_p, at low (z ~ 0) and high (z ~ 6.5) redshifts are discussed. It is shown that the distribution of the most accurate estimates of Delta mu/mu = (mu_obs - mu_lab)/mu_lab ranging between z = 0 and z ~ 1100 can be approximated by a power low Delta mu/mu = k_mu (1+z)^p, with k_mu = (1.7 +/- 0.3)x10^-8 and p = 1.99 +/- 0.03, implying a dynamical nature of the scalar field(s).

    ↳ astro-ph.COhep-ph0 citations
26. 26*

    Tidal Deformation and Dissipation of Rotating Black Holes

    Horng Sheng Chia🇳🇱

    We show that rotating black holes do not experience any tidal deformation when they are perturbed by a weak and adiabatic gravitational field. The tidal deformability of an object is quantified by the so-called "Love numbers", which describe the object's linear response to its external tidal field. In this work, we compute the Love numbers of Kerr black holes and find that they vanish identically. We also compute the dissipative part of the black hole's tidal response, which is non-vanishing due to the absorptive nature of the event horizon. Our results hold for arbitrary values of black hole spin, for both the electric-type and magnetic-type perturbations, and to all orders in the multipole expansion of the tidal field. The boundary conditions at the event horizon and at asymptotic infinity are incorporated in our study, as they are crucial for understanding the way in which these tidal effects are mapped onto gravitational-wave observables. In closing, we address the ambiguity issue of Love numbers in General Relativity, which we argue is resolved when those boundary conditions are taken into account. Our findings provide essential inputs for current efforts to probe the nature of compact objects through the gravitational waves emitted by binary systems.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2021)·246 citations
27. 27*

    Uncertainty relations: curiosities and inconsistencies

    Krzysztof Urbanowski🇵🇱

    Analyzing general uncertainty relations one can find that there can exist such pairs of non-commuting observables $A$ and $B$ and such vectors that the lower bound for the product of standard deviations $\Delta A$ and $\Delta B$ calculated for these vectors is zero: $\Delta A\cdot \Delta B\ge 0$. Here we discuss examples of such cases and some other inconsistencies which can be found performing a rigorous analysis of the uncertainty relations in some special cases. As an illustration of such cases matrices $(2\times 2)$ and $(3\times 3)$ and the position--momentum uncertainty relation for a quantum particle in the box are considered. The status of the uncertainty relation in $\mathcal{P}\mathcal{T}$--symmetric quantum theory and the problems associated with it are also studied.

    ↳ quant-phhep-phhep-thSymmetry(2020)·3 citations

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