Fri·Sep 25, 2020Friday·September 25, 2020

1. 01*

   Moments $n=2$ and $n=3$ of the Wilson twist-two operators at three loops in the RI${}^{\prime }$/SMOM scheme

   Bernd A. Kniehl🇩🇪 · Oleg L. Veretin🇩🇪

   We study the renormalization of the matrix elements of the twist-two non-singlet bilinear quark operators, contributing to the $n=2$ and $n=3$ moments of the structure functions, at next-to-next-to-next-to-leading order in QCD perturbation theory at the symmetric subtraction point. This allows us to obtain conversion factors between the $\overline{\mathrm{MS}}$ scheme and the regularization-invariant symmetric momentum subtraction (RI/SMOM, RI${}^{\prime }$/SMOM) schemes. The obtained results can be used to reduce errors in determinations of moments of structure functions from lattice QCD simulations. The results are given in Landau gauge.

   hep-phhep-latNPB(2020)·16 citations
2. 02*

   Contact interaction analysis of pion GTMDs

   Jin-Li Zhang🇨🇳 · Zhu-Fang Cui🇨🇳 · Jia-Lun Ping🇨🇳 · Craig D. Roberts🇨🇳

   A contact interaction is used to calculate an array of pion twist-two, -three and -four generalised transverse light-front momentum dependent parton distribution functions (GTMDs). Despite the interaction's simplicity, many of the results are physically relevant, amongst them a statement that GTMD size and shape are largely prescribed by the scale of emergent hadronic mass. Moreover, proceeding from GTMDs to generalised parton distributions (GPDs), it is found that the pion's mass distribution form factor is harder than its electromagnetic form factor, which is harder than the gravitational pressure distribution form factor; the pressure in the neighbourhood of the pion's core is commensurate with that at the centre of a neutron star; the shear pressure is maximal when confinement forces become dominant within the pion; and the spatial distribution of transversely polarised quarks within the pion is asymmetric. Regarding transverse momentum dependent distribution functions (TMDs), their magnitude and domain of support decrease with increasing twist. The simplest Wigner distribution associated with the pion's twist-two dressed-quark GTMD is sharply peaked on the kinematic domain associated with valence-quark dominance; has a domain of negative support; and broadens as the transverse position variable increases in magnitude.

   hep-phhep-exhep-latnucl-ex+1EPJC(2021)·60 citations
3. 03*

   Fiducial $q_T$ resummation of color-singlet processes at N${}^3$LL+NNLO

   Thomas Becher🇨🇭 · Tobias Neumann🇺🇸

   We present a framework for $q_T$ resummation at N${}^3$LL+NNLO accuracy for arbitrary color-singlet processes based on a factorization theorem in SCET. Our implementation CuTe-MCFM is fully differential in the Born kinematics and matches to large-$q_T$ fixed-order predictions at relative order ${\alpha }_s^2$. It provides an efficient way to estimate uncertainties from fixed-order truncation, resummation, and parton distribution functions. In addition to $W^{\pm }$, $Z$ and $H$ production, also the diboson processes $\gamma \gamma ,Z\gamma ,ZH$ and $W^{\pm }H$ are available, including decays. We discuss and exemplify the framework with several direct comparisons to experimental measurements as well as inclusive benchmark results. In particular, we present novel results for $\gamma \gamma$ and $Z\gamma$ at N${}^3$LL+NNLO and discuss in detail the power corrections induced by photon isolation requirements.

   hep-phhep-exJHEP(2021)·97 citations
4. 04*

   Proton Decay in Product Group Unification

   Jason L. Evans🇨🇳 · Masahiro Ibe🇯🇵 · Tsutomu T. Yanagida🇨🇳

   Product group unification is an attractive alternative to simple grand unification. It solves the infamous doublet-triplet splitting problem and the dimension-5 proton decay problems without introducing any fine-tuning. Furthermore, the matter multiplets are still embedded into unified SU(5) representations. In this paper, we discuss proton decay of the simplest product group unification model based on SU(5)XU(2)_H . We find that the minimal setup of the model has already been excluded by dimension-6 proton decay. We also show that a simple extension of the model, with naturally generated SU(5) incomplete multiplets, can rectify this problem. We find that the proton lifetime will be in reach of coming experiments like DUNE and Hyper-K, when the mass of the incomplete multiplet is associated with the Peccei-Quinn symmetry breaking. In this case, the dark matter may be an admixture of the Wino LSP and the axion.

   hep-phPRD(2021)·3 citations
5. 05*

   Theoretical Analysis of Antineutron-Nucleus Data needed for Antineutron Mirrors in Neutron-Antineutron Oscillation Experiments

   K.V. Protasov🇫🇷 · V. Gudkov🇺🇸 · E. A. Kupriyanova🇷🇺 · V.V.Nesvizhevsky🇫🇷 · W.M. Snow🇺🇸 · A.Yu. Voronin🇷🇺

   The values of the antineutron-nucleus scattering lengths, and in particular their imaginary parts, are needed to evaluate the feasibility of using neutron mirrors in laboratory experiments to search for neutron-antineutron oscillations. We analyze existing experimental and theoretical constraints on these values with emphasis on low $A$ nuclei and use the results to suggest materials for the neutron/antineutron guide and to evaluate the systematic uncertainties in estimating the neutron-antineutron oscillation time. As an example we discuss a scenario for a future neutron-antineutron oscillation experiment proposed for the European Spallation Source. We also suggest future experiments which can provide a better determination of the values of antineutron-nuclei scattering lengths.

   hep-phnucl-exnucl-thPRD(2020)·18 citations
6. 06*

   Theoretical bounds on dark matter masses

   Xavier Calmet🇬🇧 · Folkert Kuipers🇬🇧

   In this letter, we show that quantum gravity leads to lower and upper bounds on the masses of dark matter candidates. These bounds depend on the spins of the dark matter candidates and the nature of interactions in the dark matter sector. For example, for singlet scalar dark matter, we find a mass range $10^{-3}\mathrm{eV}\lesssim m_{\varphi }\lesssim 10^7\mathrm{eV}$. The lower bound comes from limits on fifth force type interactions and the upper bound from the lifetime of the dark matter candidate.

   hep-phhep-thPLB(2021)·16 citations
7. 07*

   Prediction of possible $D{K}_1$ bound states

   Xiang-Kun Dong🇨🇳 · Bing-Song Zou🇨🇳

   Stimulated by recent experimental observation of $X_1(2900)$ just below the ${\bar{D}}_{1}K$ threshold, we extend our previous study of ${\bar{D}}_{1}D$ S-wave bound state by vector meson exchange to ${\bar{D}}_{1}K$ system as well as similar $\bar{D}{K}_1$, $D_{1}K$ and $D{K}_1$ systems to look for possible bound states. We find that the potential of $D{K}_1$ is attractive and strong enough to form bound states with mass around 3110 MeV for $D{K}_1(1270)$ and 3240 MeV for $D{K}_1(1400)$. $D_{1}K$ is also attractive but weaker, hardly enough to form bound states. While $\bar{D}{K}_1$ becomes further less attractive, the potential between ${\bar{D}}_{1}K$ is the weakest, definitely too weak to form any bound state, which excludes the recently observed $X_1(2900)$ to be a ${\bar{D}}_{1}K$ bound state. We also give the decay properties of the predicted $D{K}_1$ bound states.

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

   MeV-scale Seesaw and Leptogenesis

   Valerie Domcke🇨🇭 · Marco Drewes🇧🇪 · Marco Hufnagel🇩🇪 · Michele Lucente🇧🇪

   We study the type-I seesaw model with three right-handed neutrinos and Majorana masses below the pion mass. In this mass range, the model parameter space is not only strongly constrained by the requirement to explain the light neutrino masses, but also by experimental searches and cosmological considerations. In the existing literature, three disjoint regions of potentially viable parameter space have been identified. In one of them, all heavy neutrinos decay shortly before big bang nucleosynthesis. In the other two regions, one of the heavy neutrinos either decays between BBN and the CMB decoupling or is quasi-stable. We show that previously unaccounted constraints from photodisintegration of nuclei practically rule out all relevant decays that happen between BBN and the CMB decoupling. Quite remarkably, if all heavy neutrinos decay before BBN, the baryon asymmetry of the universe can be quite generically explained by low-scale leptogenesis, i.e. without further tuning in addition to what is needed to avoid experimental and cosmological constraints. This motivates searches for heavy neutrinos in pion decay experiments.

   hep-phastro-ph.COJHEP(2021)·37 citations
9. 09*

   Constructing PineAPPL grids on hardware accelerators

   Stefano Carrazza🇮🇹 · Juan M. Cruz-Martinez🇮🇹 · Christopher Schwan🇮🇹

   In this proceedings we demonstrate how to implement and construct the PineAPPL grids, designed for fast-interpolation of Monte Carlo simulation with electroweak and QCD corrections, using the VegasFlow framework for Monte Carlo simulation on hardware accelerators. We provide an example of synchronous and asynchronous filling operations of PineAPPL grids from Monte Carlo events generated by VegasFlow. We compare the performance of this procedure on multithreading CPU and GPU.

   hep-phhep-exphysics.comp-phPoS(2021)·1 citation
10. 10*

    PeV Sterile Masses from D-Brane Instantons -- Motivating Stringy Neutrino Options?

    Jim Talbert🇩🇰

    We show that when sterile Majorana neutrino masses are generated non-perturbatively through instantonic interactions in certain classes of string compactifications (e.g. Type IIA orientifold models with intersecting D-branes), then the eigenvalue spectrum for the tree-level mass term $M_p$ can be within the preferred range of the Neutrino Option resolution to the electroweak (EW) hierarchy and neutrino mass problems of the Standard Model, i.e. $M_p\sim$ PeV. This mechanism holds without tuning for a broad range of string scales, thereby motivating a novel class of string-completed Neutrino Options spanning the light neutrino mass, EW, and deep ultraviolet scales.

    hep-phhep-th1 citation
11. 11*

    The Hierarchy Problem: From the Fundamentals to the Frontiers

    Seth Koren🇺🇸

    We begin this thesis with an extensive pedagogical introduction aimed at clarifying the foundations of the hierarchy problem. After introducing effective field theory, we discuss renormalization at length from a variety of perspectives. We focus on conceptual understanding and connections between approaches, while providing a plethora of examples for clarity. With that background we can then clearly understand the hierarchy problem, which is reviewed primarily by introducing and refuting common misconceptions thereof. We next discuss some of the beautiful classic frameworks to approach the issue. However, we argue that the LHC data have qualitatively modified the issue into `The Loerarchy Problem'---how to generate an IR scale without accompanying visible structure---and we discuss recent work on this approach. In the second half, we present some of our own work in these directions, beginning with explorations of how the Neutral Naturalness approach motivates novel signatures of electroweak naturalness at a variety of physics frontiers. Finally, we propose a New Trail for Naturalness and suggest that the physical breakdown of EFT, which gravity demands, may be responsible for the violation of our EFT expectations at the LHC.

    hep-phhep-th35 citations
12. 12*

    Joint thrust and TMD resummation in electron-positron and electron-proton collisions

    Yiannis Makris🇮🇹 · Felix Ringer🇺🇸 · Wouter J. Waalewijn🇳🇱

    We present the framework for obtaining precise predictions for the transverse momentum of hadrons with respect to the thrust axis in $e^{+}{e}^{-}$ collisions. This will enable a precise extraction of transverse momentum dependent (TMD) fragmentation functions from a recent measurement by the Belle Collaboration. Our analysis takes into account, for the first time, the nontrivial interplay between the hadron transverse momentum and the cut on the thrust event shape. To this end, we identify three different kinematic regions, derive the corresponding factorization theorems within Soft Collinear Effective Theory, and present all ingredients needed for the joint resummation of the transverse momentum and thrust spectrum at NNLL accuracy. One kinematic region can give rise to non-global logarithms (NGLs), and we describe how to include the leading NGLs. We also discuss alternative measurements in $e^{+}{e}^{-}$ collisions that can be used to access the TMD fragmentation function. Finally, by using crossing symmetry, we obtain a new way to constrain TMD parton distributions, by measuring the displacement of the thrust axis in $ep$ collisions.

    hep-phhep-exnucl-exnucl-thJHEP(2021)·26 citations
13. 13*

    Axion-Radiation Conversion by Super and Normal Conductors

    Aiichi Iwazaki🇯🇵

    We have proposed a method for the detection of dark matter axion. It uses superconductor under strong magnetic field. As is well known, the dark matter axion induces oscillating electric field under magnetic field. The electric field is proportional to the magnetic field and makes charged particles oscillate in conductors. Then, radiations of electromagnetic fields are produced. Radiation flux depends on how large the electric field is induced and how large the number of charged particles is present in the conductors. We show that the electric field in superconductor is essentially identical to the one induced in vacuum. It is proportional to the magnetic field. It is only present in the surface because of Meissner effect. On the other hand, although the magnetic field can penetrates the normal conductor, the oscillating electric field is only present in the surface of the conductor because of the skin effect. The strength of the electric field induced in the surface is equal to the one in vacuum. We obtain the electric field in the superconductor by solving equations of electromagnetic fields coupled with axion and Cooper pair described by Ginzburg-Landau model. The electric field in the normal conductor is obtained by solving equations of electromagnetic fields in the conductor coupled with axion. We compare radiation flux from the cylindrical superconductor with that from the normal conductor with same size. We find that the radiation flux from the superconductor is a hundred times larger than the flux from the normal conductor. We also show that when we use superconducting resonant cavity, we obtain radiation energy generated in the cavity two times of the order of the magnitude larger than that in normal conducting resonant cavity.

    hep-phNPB(2021)·13 citations
14. 14*

    Parton distributions in radiative corrections to the cross section of electron-proton scattering

    V.S. Fadin🇷🇺 · R.E. Gerasimov🇷🇺

    The structure function approach and the parton picture, developed for the theoretical description of the deep inelastic electron-proton scattering, also proved to be very effective for calculation of radiative corrections in Quantum Electrodynamics. We use them to calculate radiative corrections to the cross section of electron-proton scattering due to electron-photon interaction, in the experimental setup with the recoil proton detection, proposed by A.A. Vorobev to measure the proton radius. In the one-loop approximation, explicit expressions for these corrections are obtained for arbitrary momentum transfers. It is shown that, at momentum transfers small compared with the proton mass, various contributions to the corrections mutually cancel each other with power accuracy. In two loops, the corrections are obtained in the leading logarithmic approximation.

    hep-phnucl-thEPJA(2021)·1 citation
15. 15*

    Electromagnetic Bursts from Mergers of Oscillons in Axion-like Fields

    Mustafa A. Amin🇺🇸 · Zong-Gang Mou🇺🇸

    We investigate the bursts of electromagnetic and scalar radiation resulting from the collision, and merger of oscillons made from axion-like particles using 3+1 dimensional lattice simulations of the coupled axion-gauge field system. The radiation into photons is suppressed before the merger. However, it becomes the dominant source of energy loss after the merger if a resonance condition is satisfied. Conversely, the radiation in scalar waves is dominant during initial merger phase but suppressed after the merger. The backreaction of scalar and electromagnetic radiation is included in our simulations. We evolve the system long enough to see that the resonant photon production extracts a significant fraction of the initial axion energy, and again falls out of the resonance condition. We provide a parametric understanding of the time, and energy scales involved in the process and discuss observational prospects of detecting the electromagnetic signal.

    ↳ astro-ph.COhep-phJCAP(2021)·50 citations
16. 16*

    M-theory, Black Holes and Cosmology

    Renata Kallosh🇺🇸

    This paper is dedicated to Mike Duff on the occasion of his 70th birthday. I discuss some issues of M-theory/string theory/supergravity closely related to Mike's interests. I describe a relation between STU black hole entropy, Cayley hyperdeterminant, Bhargava cube and a 3-qubit Alice, Bob, Charlie triality symmetry. I shortly describe my recent work with Gunaydin, Linde, Yamada on M-theory cosmology, inspired by the work of Duff with Ferrara and Borsten, Levay, Marrani et al. Here we have 7-qubits, a party including Alice, Bob, Charlie, Daisy, Emma, Fred, George. Octonions and Hamming error correcting codes are at the base of these models. They lead to 7 benchmark targets of future CMB missions looking for primordial gravitational wave from inflation. I also show puzzling relations between the fermion mass eigenvalues in these cosmological models, exceptional Jordan eigenvalue problem, and black hole entropy. The symmetry of our cosmological models is illustrated by beautiful pictures of a Coxeter projection of the root system of E7.

    ↳ hep-thastro-ph.COhep-phmath-ph+1Proc.Roy.Soc.Lond.A(2021)·4 citations
17. 17*

    Solitary wave solutions of FKPP equation using Homogeneous balance method(HB method)

    Yirui Yang🇨🇳 · Wei Kou🇨🇳 · Xiaopeng Wang🇨🇳 · Xurong Chen🇨🇳

    In this paper, we use the homogeneous balance(HB) method is used to construct function transformation to solve the nonlinear development equation||Fisher-Kolomogror-Pertrovskii-Piskmov equation (FKPP equation), then the exact solution of FKPP equation is obtained, and the solutionis converted into the form of isolated wave solution. Finally, we have shown the solution of FKPPequation in some picture forms, and the rationality of the solution in this paper can be verified byusing the pictures.

    ↳ nlin.PShep-phnlin.SI5 citations
18. 18*

    First-Order General-Relativistic Viscous Fluid Dynamics

    Fabio S. Bemfica🇧🇷 · Marcelo M. Disconzi🇺🇸 · Jorge Noronha🇺🇸

    We present the first generalization of Navier-Stokes theory to relativity that satisfies all of the following properties: (a) the system coupled to Einstein's equations is causal and strongly hyperbolic; (b) equilibrium states are stable; (c) all leading dissipative contributions are present, i.e., shear viscosity, bulk viscosity, and thermal conductivity; (d) non-zero baryon number is included; (e) entropy production is non-negative in the regime of validity of the theory; (f) all of the above holds in the nonlinear regime without any simplifying symmetry assumptions. These properties are accomplished using a generalization of Eckart's theory containing only the hydrodynamic variables, so that no new extended degrees of freedom are needed as in Müller-Israel-Stewart theories. Property (b), in particular, follows from a more general result that we also establish, namely, sufficient conditions that when added to stability in the fluid's rest frame imply stability in any reference frame obtained via a Lorentz transformation. All our results are mathematically rigorously established. The framework presented here provides the starting point for systematic investigations of general-relativistic viscous phenomena in neutron star mergers.

    ↳ gr-qchep-phhep-thnucl-thPRX(2022)·237 citations
19. 19*

    Chiral vortical effect for vector fields

    G. Yu. Prokhorov🇷🇺 · O.V. Teryaev🇷🇺 · V.I. Zakharov🇷🇺

    We consider photonic vortical effect, i.e. the difference of the flows of left- and right-handed photons along the vector of angular velocity in rotating photonic medium. Two alternative frameworks to evaluate the effect are considered, both of which have already been tried in the literature. First, the standard thermal fied theory and, alternatively, Hawking-radiation-type derivation. In our earlier attempt to compare the two approaches, we found a crucial factor of two difference. Here we revisit the problem, paying more attention to details of infrared regularizations. We find out that introduction of an infinitesimal mass of the vector field brings the two ways of evaluating the chiral vortical effect into agreement with each other. Some implications, both on the theoretical and phenomenological sides, are mentioned.

    ↳ hep-thhep-phnucl-thPRD(2021)·16 citations
20. 20*

    Constraining Dark Matter properties with the first generation of stars

    Cosmin Ilie🇺🇸 · Caleb Levy🇺🇸 · Jacob Pilawa🇺🇸 · Saiyang Zhang🇺🇸

    Dark Matter (DM) can be trapped by the gravitational field of any star, since collisions with nuclei in dense environments can slow down the DM particle below the escape velocity ($v_{esc}$) at the surface of the star. If captured, the DM particles can self-annihilate, and, therefore, provide a new source of energy for the star. We investigate this phenomenon for capture of DM particles by the first generation of stars [Population III (Pop III) stars], by using the multiscatter capture formalism. Pop III stars are particularly good DM captors, since they form in DM-rich environments, at the center of$\sim 10^6{M}_{\odot }$ DM minihalos, at redshifts $z\sim 15$. Assuming a DM-proton scattering cross section ($\sigma )$ at the current deepest exclusion limits provided by the XENON1T experiment, we find that captured DM annihilations at the core of Pop III stars can lead, via the Eddington limit, to upper bounds in stellar masses that can be as low as a few $M_{\odot }$ if the ambient DM density (${\rho }_X$) at the location of the Pop III star is sufficiently high. Conversely, when Pop III stars are identified, one can use their observed mass ($M_{\star }$) to place bounds on ${\rho }_X\sigma$. Using adiabatic contraction to estimate the ambient DM density in the environment surrounding Pop III stars, we place projected upper limits on $\sigma$, for $M_{\star }$ in the $100-1000M_{\odot }$ range, and find bounds that are competitive with, or deeper than, those provided by the most sensitive current direct detection experiments for both spin independent and spin dependent interactions, for a wide range of DM masses. Most intriguingly, we find that Pop III stars with mass $M_{\star }\gtrsim 300M_{\odot }$ could be used to probe the SD proton-DM cross section below the "neutrino floor," i.e. the region of parameter space where DM direct detection experiments will soon become overwhelmed by neutrino backgrounds.

    ↳ astro-ph.COhep-phPRD(2021)·33 citations
21. 21*

    Probing below the neutrino floor with the first generation of stars

    Cosmin Ilie🇺🇸 · Caleb Levy🇺🇸 · Jacob Pilawa🇺🇸 · Saiyang Zhang🇺🇸

    We show that the mere observation of the first stars (Pop III stars) in the universe can be used to place tight constraints on the strength of the interaction between dark matter and regular, baryonic matter. We apply this technique to a candidate Pop III stellar complex discovered with the Hubble Space Telescope at $z\sim 7$ and find bounds that are competitive with, or even stronger than, current direct detection experiments, such as XENON1T, for dark matter particles with mass ($m_X$) larger than about $100$ GeV. We also show that the discovery of sufficiently massive Pop III stars could be used to bypass the main limitations of direct detection experiments: the neutrino background to which they will be soon sensitive.

    ↳ astro-ph.COhep-ph15 citations
22. 22*

    Quantum Formation of Topological Defects

    Mainak Mukhopadhyay🇺🇸 · Tanmay Vachaspati🇺🇸 · George Zahariade🇺🇸

    We consider quantum phase transitions with global symmetry breakings that result in the formation of topological defects. We evaluate the number densities of kinks, vortices, and monopoles that are produced in $d=1,2,3$ spatial dimensions respectively and find that they scale as $t^{-d/2}$ and evolve towards attractor solutions that are independent of the quench timescale. For $d=1$ our results apply in the region of parameters $\lambda \tau /m\ll 1$ where $\lambda$ is the quartic self-interaction of the order parameter, $\tau$ is the quench timescale, and $m$ the mass parameter.

    ↳ hep-thcond-mat.otherhep-phquant-phPRD(2020)·9 citations
23. 23*

    Magnetic field effect on pion superfluid

    Shijun Mao🇨🇳

    Magnetic field effect on pion superfluid phase transition is investigated in frame of a Pauli-Villars regularized NJL model. Instead of directly dealing with charged pion condensate, we apply the Goldstone's theorem (massless Goldstone boson ${\pi }^{+}$) to determine the onset of pion superfluid phase, and obtain the phase diagram in magnetic field, temperature, isospin and baryon chemical potential space. At weak magnetic field, it is analytically proved that the critical isospin chemical potential of pion superfluid phase transition is equal to the mass of ${\pi }^{+}$ meson in magnetic field. The pion superfluid phase is retarded to higher isospin chemical potential, and can survive at higher temperature and higher baryon chemical potential under external magnetic field.

    ↳ nucl-thhep-phPRD(2020)·6 citations
24. 24*

    Dynamical energy loss formalism: from describing suppression patterns to implications for future experiments

    Magdalena Djordjevic🇷🇸 · Dusan Zigic🇷🇸 · Bojana Blagojevic🇷🇸 · Jussi Auvinen🇷🇸 · Igor Salom🇷🇸 · Marko Djordjevic🇷🇸

    Understanding properties of Quark-Gluon Plasma requires an unbiased comparison of experimental data with theoretical predictions. To that end, we developed the dynamical energy loss formalism which, in distinction to most other methods, takes into account a realistic medium composed of dynamical scattering centers. The formalism also allows making numerical predictions for a wide number of observables with the same parameter set fixed to standard literature values. In this proceedings, we overview our recently developed DREENA-C and DREENA-B frameworks, where DREENA is a computational implementation of the dynamical energy loss formalism, and where C stands for constant temperature QCD medium, while B stands for the medium modeled by 1+1D Bjorken expansion. At constant temperature our predictions overestimate $v_2$, in contrast to other models, but consistent with simple analytical estimates. With Bjorken expansion, we have a good agreement of the predictions with both $R_{AA}$ and $v_2$ measurements. We find that introducing medium evolution has a larger effect on $v_2$ predictions, but for precision predictions it has to be taken into account in $R_{AA}$ predictions as well. Based on numerical calculations and simple analytical derivations, we also propose a new observable, which we call path length sensitive suppression ratio, for which we argue that the path length dependence can be assessed in a straightforward manner. We also argue that $Pb+Pb$ vs. $Xe+Xe$ measurements make a good system to assess the path length dependence. As an outlook, we expect that introduction of more complex medium evolution (beyond Bjorken expansion) in the dynamical energy loss formalism can provide a basis for a state of the art QGP tomography tool - e.g. to jointly constrain the medium properties from the point of both high pt and low pt data.

    ↳ nucl-thhep-phNPA(2019)·3 citations
25. 25*

    Restoration of chiral symmetry in cold and dense Nambu--Jona-Lasinio model with tensor renormalization group

    Shinichiro Akiyama🇯🇵 · Yoshinobu Kuramashi🇯🇵 · Takumi Yamashita🇯🇵 · Yusuke Yoshimura🇯🇵

    We analyze the chiral phase transition of the Nambu--Jona-Lasinio model in the cold and dense region on the lattice developing the Grassmann version of the anisotropic tensor renormalization group algorithm. The model is formulated with the Kogut--Susskind fermion action. We use the chiral condensate as an order parameter to investigate the restoration of the chiral symmetry. The first-order chiral phase transition is clearly observed in the dense region at vanishing temperature with $\mu /T\sim O(10^3)$ on a large volume of $V=1024^4$. We also present the results for the equation of state.

    ↳ hep-lathep-phhep-thnucl-thJHEP(2021)·38 citations
26. 26*

    Dilepton production in microscopic transport theory with in-medium $\rho$-meson spectral function

    A.B. Larionov🇩🇪 · U. Mosel🇩🇪 · L. von Smekal🇩🇪

    We use the microscopic GiBUU transport model to calculate dilepton ($e^{+}{e}^{-}$) production in heavy-ion collisions at SIS18 energies focusing on the effect of collisional broadening of the $\rho$-meson. The collisional width of the $\rho$-meson at finite temperature and baryon density in nuclear matter is calculated on the basis of the collision integral of the GiBUU model. A systematic comparison with HADES data on dilepton production in heavy-ion collisions is performed. The collisional broadening of the $\rho$ improves the agreement between theory and experiment for the dilepton invariant-mass distributions near the $\rho$ pole mass and for the excess radiation in Au+Au at $1.23A$ GeV. We furthermore show that some remaining underprediction of the experimental dilepton spectra in C+C at $1A$ GeV and Au+Au at $1.23A$ GeV at intermediate invariant masses $0.2-0.4$ GeV can be accounted for by adjusting the $pn$ bremsstrahlung cross section in a way to agree with the inclusive dilepton spectrum from $dp$ collisions at $1.25A$ GeV.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2021)·20 citations
27. 27*

    A0--condensation in quark-gluon plasma with finite baryon density

    M. Bordag🇩🇪 · V. Skalozub🇺🇦

    In the present paper, we return to the problem on a spontaneous generation of the $A_0$-background field in QCD at finite temperature and include in addition a quark chemical potential, $\mu$. We reproduce the known expressions in terms of Bernoulli's polynomials for the gluons and quarks using the same formalism. Then we calculate the $\mu$-dependence, both for small $\mu$ as expansion, and numerically for finite $\mu$. One result is that the chemical potential only weakly changes the values of the condensed field, but quite strongly deepens the minima of the effective potential. The gauge dependence of the condensation is discussed in terms of Nielsen's identity. It also is expressed in terms of Polyakov's loop. Both these representations guarantee gauge invariance of the condensation phenomenon. Also, we discuss the dependence of the Polyakov loop in the minimum of the effective potential on the chemical potential.

    ↳ hep-thhep-phEPJC(2021)·5 citations
28. 28*

    Impulsively Excited Gravitational Quantum States: Echoes and Time-resolved Spectroscopy

    I. Tutunnikov🇮🇱 · K. V. Rajitha🇮🇱 · A. Yu. Voronin🇷🇺 · V. V. Nesvizhevsky🇫🇷 · I. Sh. Averbukh🇮🇱

    We theoretically study an impulsively excited quantum bouncer (QB) - a particle bouncing off a surface in the presence of gravity. A pair of time-delayed pulsed excitations is shown to induce a wave-packet echo effect - a partial rephasing of the QB wave function appearing at twice the delay between pulses. In addition, an appropriately chosen observable [here, the population of the ground gravitational quantum state (GQS)] recorded as a function of the delay is shown to contain the transition frequencies between the GQSs, their populations, and partial phase information about the wave packet quantum amplitudes. The wave-packet echo effect is a promising candidate method for precision studies of GQSs of ultra-cold neutrons, atoms, and anti-atoms confined in closed gravitational traps.

    ↳ quant-phhep-phphysics.atom-phphysics.ins-detPRL(2021)·5 citations
29. 29*

    Search for Efficient Formulations for Hamiltonian Simulation of non-Abelian Lattice Gauge Theories

    Zohreh Davoudi🇺🇸 · Indrakshi Raychowdhury🇺🇸 · Andrew Shaw🇺🇸

    Hamiltonian formulation of lattice gauge theories (LGTs) is the most natural framework for the purpose of quantum simulation, an area of research that is growing with advances in quantum-computing algorithms and hardware. It, therefore, remains an important task to identify the most accurate, while computationally economic, Hamiltonian formulation(s) in such theories, considering the necessary truncation imposed on the Hilbert space of gauge bosons with any finite computing resources. This paper is a first step toward addressing this question in the case of non-Abelian LGTs, which further require the imposition of non-Abelian Gauss's laws on the Hilbert space, introducing additional computational complexity. Focusing on the case of SU(2) LGT in 1+1 D coupled to matter, a number of different formulations of the original Kogut-Susskind framework are analyzed with regard to the dependence of the dimension of the physical Hilbert space on boundary conditions, system's size, and the cutoff on the excitations of gauge bosons. The impact of such dependencies on the accuracy of the spectrum and dynamics is examined, and the (classical) computational-resource requirements given these considerations are studied. Besides the well-known angular-momentum formulation of the theory, the cases of purely fermionic and purely bosonic formulations (with open boundary conditions), and the Loop-String-Hadron formulation are analyzed, along with a brief discussion of a Quantum Link Model of the same theory. Clear advantages are found in working with the Loop-String-Hadron framework which implements non-Abelian Gauss's laws a priori using a complete set of gauge-invariant operators. Although small lattices are studied in the numerical analysis of this work, and only the simplest algorithms are considered, a range of conclusions will be applicable to larger systems and potentially to higher dimensions.

    ↳ hep-lathep-phnucl-thquant-phPRD(2021)·164 citations
30. 30*

    Two-nucleon S-wave interactions at the $SU(3)$ flavor-symmetric point with $m_{ud}\simeq m_s^{\mathrm{phys}}$: a first lattice QCD calculation with the stochastic Laplacian Heaviside method

    Ben Hörz🇺🇸 · Dean Howarth🇺🇸 · Enrico Rinaldi🇯🇵 · Andrew Hanlon🇩🇪 · Chia Cheng Chang🇯🇵 · Christopher Körber🇺🇸 · Evan Berkowitz🇺🇸 · John Bulava🇩🇰 · M.A. Clark🇺🇸 · Wayne Tai Lee🇺🇸 · Colin Morningstar🇺🇸 · Amy Nicholson🇺🇸 · Pavlos Vranas🇺🇸 · André Walker-Loud🇺🇸

    We report on the first application of the stochastic Laplacian Heaviside method for computing multi-particle interactions with lattice QCD to the two-nucleon system. Like the Laplacian Heaviside method, this method allows for the construction of interpolating operators which can be used to construct a positive definite set of two-nucleon correlation functions, unlike nearly all other applications of lattice QCD to two nucleons in the literature. It also allows for a variational analysis in which optimal linear combinations of the interpolating operators are formed that couple predominantly to the eigenstates of the system. Utilizing such methods has become of paramount importance in order to help resolve the discrepancy in the literature on whether two nucleons in either isospin channel form a bound state at pion masses heavier than physical, with the discrepancy persisting even in the $SU(3)$-flavor symmetric point with all quark masses near the physical strange quark mass. This is the first in a series of papers aimed at resolving this discrepancy. In the present work, we employ the stochastic Laplacian Heaviside method without a hexaquark operator in the basis at a lattice spacing of $a\sim 0.086$~fm, lattice volume of $L=48a\simeq 4.1$~fm and pion mass $m_{\pi }\simeq 714$ MeV. With this setup, the observed spectrum of two-nucleon energy levels strongly disfavors the presence of a bound state in either the deuteron or dineutron channel.

    ↳ hep-lathep-phnucl-exnucl-thPRC(2021)·93 citations
31. 31*

    Gas Heating from Spinning and Non-Spinning Evaporating Primordial Black Holes

    Ranjan Laha🇨🇭 · Philip Lu🇺🇸 · Volodymyr Takhistov🇺🇸

    Primordial black holes (PBHs) from the early Universe constitute a viable dark matter (DM) candidate and can span many orders of magnitude in mass. Light PBHs with masses around $10^{15}$ g contribute to DM and will efficiently evaporate through Hawking radiation at present time, leading to a slew of observable signatures. The emission will deposit energy and heat in the surrounding interstellar medium. We revisit the constraints from dwarf galaxy heating by evaporating non-spinning PBHs and find that conservative constraints from Leo T dwarf galaxy are significantly weaker than previously suggested. Furthermore, we analyse gas heating from spinning evaporating PBHs. The resulting limits on PBH DM abundance are found to be stronger for evaporating spinning PBHs than for non-spinning PBHs.

    ↳ astro-ph.COastro-ph.HEhep-phhep-thPLB(2021)·69 citations
32. 32*

    Improved reconstruction of a stochastic gravitational wave background with LISA

    Raphael Flauger🇺🇸 · Nikolaos Karnesis🇫🇷 · Germano Nardini🇳🇴 · Mauro Pieroni🇬🇧 · Angelo Ricciardone🇮🇹 · Jesús Torrado🇩🇪

    We present a data analysis methodology for a model-independent reconstruction of the spectral shape of a stochastic gravitational wave background with LISA. We improve a previously proposed reconstruction algorithm that relied on a single Time-Delay-Interferometry (TDI) channel by including a complete set of TDI channels. As in the earlier work, we assume an idealized equilateral configuration. We test the improved algorithm with a number of case studies, including reconstruction in the presence of two different astrophysical foreground signals. We find that including additional channels helps in different ways: it reduces the uncertainties on the reconstruction; it makes the global likelihood maximization less prone to falling into local extrema; and it efficiently breaks degeneracies between the signal and the instrumental noise.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·190 citations
33. 33*

    Non-linear and weak-coupling expansion in Quantum Field Theory

    Vincenzo Branchina🇮🇹 · Alberto Chiavetta🇮🇹 · Filippo Contino🇮🇹

    A formal expansion for the Green's functions of an interacting quantum field theory in a parameter that somehow encodes its "distance" from the corresponding non-interacting one was introduced more than thirty years ago, and has been recently reconsidered in connection with its possible application to the renormalization of non-hermitian theories. Besides this new and interesting application, this expansion has special properties already when applied to ordinary (i.e. hermitian) theories, and in order to disentangle the peculiarities of the expansion itself from those of non-hermitian theories, it is worth to push further the investigation limiting first the analysis to ordinary theories. In the present work we study some aspects related to the renormalization of a scalar theory within the framework of such an expansion. Due to its peculiar properties, it turns out that at any finite order in the expansion parameter the theory looks as non-interacting. We show that when diagrams of appropriate classes are resummed, this apparent drawback disappears and the theory recovers its interacting character. In particular we have seen that with a certain class of diagrams, the weak-coupling expansion results are recovered, thus establishing a bridge between the two expansions.

    ↳ hep-thhep-phmath-phmath.MP2 citations
34. 34*

    Solar-Mass Primordial Black Holes Explain NANOGrav Hint of Gravitational Waves

    Kazunori Kohri🇯🇵 · Takahiro Terada🇰🇷

    The NANOGrav collaboration for the pulsar timing array (PTA) observation recently announced evidence of an isotropic stochastic process, which may be the first detection of the stochastic gravitational-wave (GW) background. We discuss the possibility that the signal is caused by the second-order GWs associated with the formation of solar-mass primordial black holes (PBHs). This possibility can be tested by future interferometer-type GW observations targeting the stochastic GWs from merger events of solar-mass PBHs as well as by updates of PTA observations.

    ↳ astro-ph.COgr-qchep-phhep-thPLB(2021)·207 citations
35. 35*

    Boundary contributions to three loop superstring amplitudes

    Kowshik Bettadapura🇨🇳 · Hai Lin🇨🇳

    In type II superstring theory, the vacuum amplitude at a given loop order $g$ can receive contributions from the boundary of the compactified, genus $g$ supermoduli space of curves ${\overline{\mathfrak{M}}}_g$. These contributions capture the long distance or infrared behaviour of the amplitude. The boundary parametrises degenerations of genus $g$ super Riemann surfaces. A holomorphic projection of the supermoduli space onto its reduced space would then provide a way to integrate the holomorphic, superstring measure and thereby give the superstring vacuum amplitude at $g$-loop order. However, such a projection does not generally exist over the bulk of the supermoduli spaces in higher genera. Nevertheless, certain boundary divisors in $\partial {\overline{\mathfrak{M}}}_g$ may holomorphically map onto a bosonic space upon composition with universal morphisms, thereby enabling an integration of the holomorphic, superstring measure here. Making use of ansatz factorisations of the superstring measure near the boundary, our analysis shows that the boundary contributions to the three loop vacuum amplitude will vanish in closed oriented type II superstring theory with unbroken spacetime supersymmetry.

    ↳ hep-thhep-phmath-phmath.AG+1J.Math.Phys.(2021)·2 citations
36. 36*

    Whispers from the dark side: Confronting light new physics with NANOGrav data

    Wolfram Ratzinger🇩🇪 · Pedro Schwaller🇩🇪

    The NANOGrav collaboration has recently observed first evidence of a gravitational wave background (GWB) in pulsar timing data. Here we explore the possibility that this GWB is due to new physics, and show that the signal can be well fit also with peaked spectra like the ones expected from phase transitions (PTs) or from the dynamics of axion like particles (ALPs) in the early universe. We find that a good fit to the data is obtained for a very strong PT at temperatures around 1 MeV to 10 MeV. For the ALP explanation the best fit is obtained for a decay constant of $F\approx 5\times 10^{17}$ GeV and an axion mass of $2\times 10^{-13}$ eV. We also illustrate the ability of PTAs to constrain the parameter space of these models, and obtain limits which are already comparable to other cosmological bounds.

    ↳ astro-ph.COhep-phSciPost Phys.(2021)·134 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.