Mon·Nov 30, 2020Monday·November 30, 2020

1. 01*

   Phase Space Sampling and Inference from Weighted Events with Autoregressive Flows

   Bob Stienen🇳🇱 · Rob Verheyen🇬🇧

   We explore the use of autoregressive flows, a type of generative model with tractable likelihood, as a means of efficient generation of physical particle collider events. The usual maximum likelihood loss function is supplemented by an event weight, allowing for inference from event samples with variable, and even negative event weights. To illustrate the efficacy of the model, we perform experiments with leading-order top pair production events at an electron collider with importance sampling weights, and with next-to-leading-order top pair production events at the LHC that involve negative weights.

   hep-phSciPost Phys.(2021)·74 citations
2. 02*

   How warm are non-thermal relics? Lyman-$\alpha$ bounds on out-of-equilibrium dark matter

   Guillermo Ballesteros🇪🇸 · Marcos A. G. Garcia🇪🇸 · Mathias Pierre🇪🇸

   We investigate the power spectrum of Non-Cold Dark Matter (NCDM) produced in a state out of thermal equilibrium. We consider dark matter production from the decay of scalar condensates (inflaton, moduli), the decay of thermalized and non-thermalized particles, and from thermal and non-thermal freeze-in. For each case, we compute the NCDM phase space distribution and the linear matter power spectrum, which features a cutoff analogous to that for Warm Dark Matter (WDM). This scale is solely determined by the equation of state of NCDM. We propose a mapping procedure that translates the WDM Lyman-$\alpha$ mass bound to NCDM scenarios. This procedure does not require expensive ad hoc numerical computations of the non-linear matter power spectrum. By applying it, we obtain bounds on several NCDM possibilities, ranging from $m_{\mathrm{DM}}\gtrsim \mathrm{EeV}$ for DM production from inflaton decay with a low reheating temperature, to sub-keV values for non-thermal freeze-in. We discuss the phenomenological implications of these results for specific examples which include strongly-stabilized and non-stabilized supersymmetric moduli, gravitino production from inflaton decay, $Z^{\prime }$ and spin-2 mediated freeze-in, and non-supersymmetric spin-3/2 DM.

   hep-phastro-ph.COgr-qchep-thJCAP(2021)·129 citations
3. 03*

   Common origin of radiative neutrino mass, dark matter and leptogenesis in scotogenic Georgi-Machacek model

   Shao-Long Chen🇨🇳 · Amit Dutta Banik🇨🇳 · Ze-Kun Liu🇨🇳

   We explore the phenomenology of the Georgi-Machacek model extended with two Higgs doublets and vector fermion doublets invariant under $SU(2{)}_L\times U(1{)}_Y\times {\mathcal{Z}}_4\times {\mathcal{Z}}_2$. The ${\mathcal{Z}}_4$ symmetry is broken spontaneously while the imposed ${\mathcal{Z}}_2$ symmetry forbids triplet fields to generate any vacuum expectation value and leading to an inert dark sector providing a viable candidate for dark matter and generate neutrino mass radiatively. Another interesting feature of the model is leptogenesis arising from decay of vector-like fermions. A detailed study of the model is pursued in search for available parameter space consistent with the theoretical and experimental observations for dark matter, neutrino physics, flavor physics, matter-antimatter asymmetry in the Universe.

   hep-phNPB(2021)·16 citations
4. 04*

   Probing Bottom-flavored Scalar Dark Matters at Loop Level

   Wei Chao🇨🇳 · JIan-guo Jiang🇨🇳 · Min Su🇨🇳

   In this paper we consider loop corrections to the spin-independent WIMP-nucleon scattering cross section in bottom-quark flavored scalar-type dark matter models. We focus on two scenarios: (a) a complex scalar dark matter with a scalar particle as the mediator; and (b) a real scalar dark matter with a vector boson as the mediator. In both scenarios, the direct detection cross sections are either spin-dependent or kinematically forbidden at the tree-level. Corrections induced by the WIMP-gluon effective operator, scalar-type WIMP-quark effective operator, and the twist-2 effective operator are calculated. Numerical results show that loop induced spin-independent WIMP-nucleon scattering cross sections are quite considerable in both scenarios.

   hep-ph2 citations
5. 05*

   Third order corrections to the semi-leptonic \boldmath{$b\to c$} and the muon decays

   Matteo Fael🇩🇪 · Kay Schönwald🇩🇪 · Matthias Steinhauser🇩🇪

   We compute corrections of order ${\alpha }_s^3$ to the decay $b\to c\ell \bar{\nu }$ taking into account massive charm quarks. In the on-shell scheme large three-loop corrections are found. However, in the kinetic scheme the three-loop corrections are below 1\% and thus perturbation theory is well under control. We furthermore provide results for the order ${\alpha }_s^3$ corrections to $b\to u\ell \bar{\nu }$ and the third-order QED corrections to the muon decay which will be important input for reducing the uncertainty of the Fermi coupling constant $G_F$.

   hep-phPRD(2021)·112 citations
6. 06*

   Flavour specific neutrino self-interaction: $H_0$ tension and IceCube

   Arindam Mazumdar🇮🇳 · Subhendra Mohanty🇮🇳 · Priyank Parashari🇮🇳

   Self-interaction in the active neutrinos is studied in the literature to alleviate the $H_0$ tension. Similar self-interaction can also explain the observed dips in the flux of the neutrinos coming from the distant astro-physical sources in IceCube detectors. In contrast to the flavour universal neutrino interaction considered for solving the $H_0$ tension, which is ruled out from particle physics experiments, we consider flavour specific neutrino interactions. We show that the values of self-interaction coupling constant and mediator mass required for explaining the IceCube dips are inconsistent with the strong neutrino self-interactions preferred by the combination of BAO, HST and Planck data. However, the required amount of self-interaction between tau neutrinos (${\nu }_{\tau }$) in inverted hierarchy for explaining IceCube dips is consistent with the moderate self-interaction region of cosmological bounds at 1-$\sigma$ level. For the case of other interactions and hierarchies, the IceCube preferred amount of self-interaction is consistent with moderate self-interaction region of cosmological bounds at 2-$\sigma$ level only.

   hep-phastro-ph.COJCAP(2022)·34 citations
7. 07*

   Bose-Einstein momentum correlations at fixed multiplicities: Lessons from an exactly solvable thermal model for $pp$ collisions at the LHC

   M.D. Adzhymambetov🇺🇦 · S.V. Akkelin🇺🇦 · Yu.M. Sinyukov🇺🇦

   Two-particle momentum correlations of $N$ identical bosons are studied in the quantum canonical ensemble. We define the latter as a properly selected subensemble of events associated with the grand canonical ensemble which is characterized by a constant temperature and a harmonic-trap chemical potential. The merits of this toy model are that it can be solved exactly, and that it demonstrates some interesting features revealed recently in small systems created in $p+p$ collisions at the LHC. We find that partial coherence can be observed in particle emission from completely thermal ensembles of events if instead of inclusive measurements one studies the two-boson distribution functions related to the events with particle numbers selected in some fixed multiplicity bins. The corresponding coherence effects increase with the multiplicity.

   hep-phhep-exnucl-exnucl-thPRD(2021)·2 citations
8. 08*

   Small-$p_T$ and large-$x$ regions for Higgs transverse momentum distributions

   Tanjona R. Rabemananjara🇮🇹

   It was shown recently that standard resummation of logarithms of $Q/p_T$ can be supplemented with the resummation of logarithmic contributions at large $x=Q^2/s$ in the case of a colourless final state such as Higgs produced via gluon fusion or the production of a lepton pair via Drell--Yan mechanism. Such an improved transverse momentum resummation takes into account soft emissions that are emitted at very small angles. We report on recent phenomenological studies of a combined threshold-improved $p_T$ and threshold resummation formalism to the Higgs boson produced at the LHC where small-$p_T$ and threshold logarithms are resummed up to NNLL and NNLL* respectively. We show that the effect of the modified $p_T$ resummation yields a faster perturbative convergence in the small-$p_T$ region while the effect of the threshold one improves the agreement with fixed-order calculations in the medium and large-$p_T$ regions.

   hep-phNucl.Part.Phys.Proc.(2021)·1 citation
9. 09*

   Gauge Baryon Number and Dibaryonic Dark Matter

   Ernest Ma (UC Riverside)🇺🇸

   The minimal standard model of quarks and leptons is extended with a set of vectorlike fermions to allow baryon number $B$ to become a gauged $U(1{)}_B$ symmetry. The $B$ assignments of the new particles are determined by renormalizable interactions with the known quarks through a color triplet scalar diquark. The spontaneous breaking of $U(1{)}_B$ by a scalar with $B=3$ results in a conserved residual global $B$ symmetry. A singlet neutral scalar with $B=2$ is a possible long-lived dark-matter candidate.

   hep-phPLB(2021)·10 citations
10. 10*

    Gauge couplings evolution from the Standard Model, through Pati-Salam theory, into $E_8$ unification of families and forces

    Francisco J. de Anda🇲🇽 · Alfredo Aranda🇲🇽 · António P. Morais🇵🇹 · Roman Pasechnik🇸🇪

    We explore the potential of ultimate unification of the Standard Model matter and gauge sectors into a single $E_8$ superfield in ten dimensions via an intermediate Pati-Salam gauge theory. Through a consistent realisation of a ${\mathbb{T}}^6/({\mathbb{Z}}_6\times {\mathbb{Z}}_2)$ orbifolding procedure accompanied by the Wilson line breaking mechanism and Renormalisation Group evolution of gauge couplings, we have established several benchmark scenarios for New Physics that are worth further phenomenological exploration.

    hep-phhep-thUniverse(2023)·6 citations
11. 11*

    Testing anomalous $H-W$ couplings and Higgs self-couplings via double and triple Higgs production at $e^{+}{e}^{-}$ colliders

    Manuel Gonzalez-Lopez🇪🇸 · Maria Herrero🇪🇸 · Paula Martinez-Suarez🇪🇸

    In the present work we study the implications at the future $e^{+}{e}^{-}$ colliders of the modified interaction vertices $WWH$, $WWHH$, $HHH$ and $HHHH$ within the context of the non-linear effective field theory given by the Electroweak Chiral Lagrangian. These vertices are given by four parameters, $a$, $b$, ${\kappa }_3$ and ${\kappa }_4$, respectively, that are independent and without any constraint from symmetry considerations in this non-linear effective Lagrangian context, given the fact the Higgs field is a singlet. This is in contrast to the Standard Model, where the vertices are related by $V_{WWH}^{\mathrm{SM}}=v{V}_{WWHH}^{\mathrm{SM}}$ and $V_{HHH}^{\mathrm{SM}}=v{V}_{HHHH}^{\mathrm{SM}}$, with $v=246$ GeV. We investigate the implications of the absence of these relations in the Electroweak Chiral Lagrangian case. We explore the sensitivity to these Higgs anomalous couplings in the two main channels at these colliders: double and triple Higgs production (plus neutrinos). Concretely, we study the access to $a$ and $b$ in $e^{+}{e}^{-}\to HH\nu \bar{\nu }$ and the access to ${\kappa }_3$ and ${\kappa }_4$ in $e^{+}{e}^{-}\to HHH\nu \bar{\nu }$. Our study of the beyond the Standard Model couplings via triple Higgs boson production at $e^{+}{e}^{-}$ colliders is novel and shows for the first time the possible accessibility to the quartic Higgs self-coupling.

    hep-phEPJC(2021)·29 citations
12. 12*

    Determining the proton content with a quantum computer

    Adrián Pérez-Salinas🇪🇸 · Juan Cruz-Martinez🇮🇹 · Abdulla A. Alhajri🇦🇪 · Stefano Carrazza🇮🇹

    We present a first attempt to design a quantum circuit for the determination of the parton content of the proton through the estimation of parton distribution functions (PDFs), in the context of high energy physics (HEP). The growing interest in quantum computing and the recent developments of new algorithms and quantum hardware devices motivates the study of methodologies applied to HEP. In this work we identify architectures of variational quantum circuits suitable for PDFs representation (qPDFs). We show experiments about the deployment of qPDFs on real quantum devices, taking into consideration current experimental limitations. Finally, we perform a global qPDF determination from collider data using quantum computer simulation on classical hardware and we compare the obtained partons and related phenomenological predictions involving hadronic processes to modern PDFs.

    hep-phhep-exquant-phPRD(2021)·76 citations
13. 13*

    Sources of Low-Energy Events in Low-Threshold Dark Matter and Neutrino Detectors

    Peizhi Du🇺🇸 · Daniel Egana-Ugrinovic🇨🇦 · Rouven Essig🇺🇸 · Mukul Sholapurkar🇺🇸

    We discuss several low-energy backgrounds to sub-GeV dark matter searches, which arise from high-energy particles of cosmic or radioactive origin that interact with detector materials. We focus in particular on Cherenkov radiation, transition radiation, and luminescence or phonons from electron-hole pair recombination, and show that these processes are an important source of backgrounds at both current and planned detectors. We perform detailed analyses of these backgrounds at several existing and proposed experiments based on a wide variety of detection strategies and levels of shielding. We find that a large fraction of the observed single-electron events in the SENSEI 2020 run originate from Cherenkov photons generated by high-energy events in the Skipper Charge Coupled Device, and from recombination photons generated in a phosphorus-doped layer of the same instrument. In a SuperCDMS HVeV 2020 run, Cherenkov photons produced in printed-circuit-boards located near the sensor likely explain the origin of most of the events containing 2 to 6 electrons. At SuperCDMS SNOLAB, radioactive contaminants inside the Cirlex located inside or on the copper side walls of their detectors will produce many Cherenkov photons, which could dominate the low-energy backgrounds. For the EDELWEISS experiment, Cherenkov or luminescence backgrounds are subdominant to their observed event rate, but could still limit the sensitivity of their future searches. We also point out that Cherenkov radiation, transition radiation, and recombination could be a significant source of backgrounds at future experiments aiming to detect dark-matter via scintillation or phonon signals. We also discuss the implications of our results for the development of superconducting qubits and low-threshold searches for coherent neutrino scattering, and comment on design strategies that can be implemented to mitigate these backgrounds.

    hep-phastro-ph.COastro-ph.IMhep-ex+1PRX(2022)·117 citations
14. 14*

    Precision from the diphoton Zh channel at FCC-hh

    Fady Bishara🇩🇪 · Stefania De Curtis🇮🇹 · Luigi Delle Rose🇮🇹 · Philipp Englert🇩🇪 · Christophe Grojean🇩🇪 · Marc Montull🇨🇭 · Giuliano Panico🇮🇹 · Alejo N. Rossia🇩🇪

    The future 100 TeV FCC-hh hadron collider will give access to rare but clean final states which are out of reach of the HL-LHC. One such process is the $Zh$ production channel in the $(\nu \bar{\nu }/{\ell }^{+}{\ell }^{-})\gamma \gamma$ final states. We study the sensitivity of this channel to the ${\mathcal{O}}_{\phi q}^{(1)}$, ${\mathcal{O}}_{\phi q}^{(3)}$, ${\mathcal{O}}_{\phi u}$, and ${\mathcal{O}}_{\phi d}$ SMEFT operators, which parametrize deviations of the $W$ and $Z$ couplings to quarks, or, equivalently, anomalous trilinear gauge couplings (aTGC). While our analysis shows that good sensitivity is only achievable for ${\mathcal{O}}_{\phi q}^{(3)}$, we demonstrate that binning in the $Zh$ rapidity has the potential to improve the reach on ${\mathcal{O}}_{\phi q}^{(1)}$. Our estimated bounds are one order of magnitude better than projections at HL-LHC and is better than global fits at future lepton colliders. The sensitivity to ${\mathcal{O}}_{\phi q}^{(3)}$ is competitive with other channels that could probe the same operator at FCC-hh. Therefore, combining the different diboson channels sizeably improves the bound on ${\mathcal{O}}_{\phi q}^{(3)}$, reaching a precision of $|\delta g_{1z}|\lesssim 2\times 10^{-4}$ on the deviations in the $ZWW$ interactions.

    hep-phhep-exJHEP(2021)·19 citations
15. 15*

    Resurrecting $b\bar{b}h$ with kinematic shapes

    Christophe Grojean🇩🇪 · Ayan Paul🇩🇪 · Zhuoni Qian🇩🇪

    The associated production of a $b\bar{b}$ pair with a Higgs boson could provide an important probe to both the size and the phase of the bottom-quark Yukawa coupling, $y_b$. However, the signal is shrouded by several background processes including the irreducible $Zh,Z\to b\bar{b}$ background. We show that the analysis of kinematic shapes provides us with a concrete prescription for separating the $y_b$-sensitive production modes from both the irreducible and the QCD-QED backgrounds using the $b\bar{b}\gamma \gamma$ final state. We draw a page from game theory and use Shapley values to make Boosted Decision Trees interpretable in terms of kinematic measurables and provide physics insights into the variances in the kinematic shapes of the different channels that help us complete this feat. Adding interpretability to the machine learning algorithm opens up the black-box and allows us to cherry-pick only those kinematic variables that matter most in the analysis. We resurrect the hope of constraining the size and, possibly, the phase of $y_b$ using kinematic shape studies of $b\bar{b}h$ production with the full HL-LHC data and at FCC-hh.

    hep-phhep-exphysics.data-anJHEP(2021)·37 citations
16. 16*

    Di-photon amplitudes in three-loop Quantum Chromodynamics

    Fabrizio Caola🇬🇧 · Andreas von Manteuffel🇺🇸 · Lorenzo Tancredi🇬🇧

    We consider the three-loop scattering amplitudes for the production of a pair of photons in quark-antiquark annihilation in Quantum Chromodynamics (QCD). We use suitably defined projectors to efficiently calculate all helicity amplitudes. We obtain relatively compact analytic results, that we write in terms of harmonic polylogarithms or, alternatively, multiple polylogarithms of up to depth three. This is the first calculation of a three-loop four-point scattering amplitude in full QCD.

    hep-phhep-thPRL(2021)·64 citations
17. 17*

    Ripples in Spacetime from Broken Supersymmetry

    Nathaniel Craig🇺🇸 · Noam Levi🇮🇱 · Alberto Mariotti🇧🇪 · Diego Redigolo🇨🇭

    We initiate the study of gravitational wave (GW) signals from first-order phase transitions in supersymmetry-breaking hidden sectors. Such phase transitions often occur along a pseudo-flat direction universally related to supersymmetry (SUSY) breaking in hidden sectors that spontaneously break $R$-symmetry. The potential along this pseudo-flat direction imbues the phase transition with a number of novel properties, including a nucleation temperature well below the scale of heavy states (such that the temperature dependence is captured by the low-temperature expansion) and significant friction induced by the same heavy states as they pass through bubble walls. In low-energy SUSY-breaking hidden sectors, the frequency of the GW signal arising from such a phase transition is guaranteed to lie within the reach of future interferometers given existing cosmological constraints on the gravitino abundance. Once a mediation scheme is specified, the frequency of the GW peak correlates with the superpartner spectrum. Current bounds on supersymmetry are compatible with GW signals at future interferometers, while the observation of a GW signal from a SUSY-breaking hidden sector would imply superpartners within reach of future colliders.

    hep-phhep-thJHEP(2020)·28 citations
18. 18*

    Spin polarization dynamics in the Gubser-expanding background

    Rajeev Singh🇵🇱 · Gabriel Sophys🇵🇱 · Radoslaw Ryblewski🇵🇱

    Evolution of spin polarization in the Gubser-expanding conformal perfect-fluid hydrodynamic background is studied. The analysis of the conformal transformation properties of the conservation laws is extended to the case of the angular momentum conservation. The explicit forms of equations of motion for spin components are derived and analysed, and some special solutions are found.

    hep-phnucl-thPRD(2021)·80 citations
19. 19*

    Progress in the Glauber model at collider energies

    David d'Enterria🇨🇭 · Constantin Loizides🇺🇸

    We review the theoretical and experimental progress in the Glauber model of multiple nucleon and/or parton scatterings, after the last 10--15 years of operation with proton and nuclear beams at the CERN Large Hadron Collider (LHC) and with various light and heavy colliding ions at the BNL Relativistic Heavy Ion Collider (RHIC). The main developments and the state-of-the-art of the field are summarized. These encompass measurements of the inclusive inelastic proton and nuclear cross sections, advances in the description of the proton and nuclear density profiles and their fluctuations, inclusion of subnucleonic degrees of freedom, experimental procedures and issues related to the determination of the collision centrality, validation of the binary scaling prescription for hard scattering cross sections, and constraints on transport properties of quark-gluon matter from varying initial-state conditions in relativistic hydrodynamics calculations. These advances confirm the validity and usefulness of the Glauber formalism for quantitative studies of QCD matter produced in high-energy collisions of systems, from protons to uranium nuclei, of vastly different size.

    hep-phhep-exnucl-exnucl-thAnn.Rev.Nucl.Part.Sci.(2021)·138 citations
20. 20*

    Explainable AI for ML jet taggers using expert variables and layerwise relevance propagation

    Garvita Agarwal🇺🇸 · Lauren Hay🇺🇸 · Ia Iashvili🇺🇸 · Benjamin Mannix🇺🇸 · Christine McLean🇺🇸 · Margaret Morris🇺🇸 · Salvatore Rappoccio🇺🇸 · Ulrich Schubert🇺🇸

    A framework is presented to extract and understand decision-making information from a deep neural network (DNN) classifier of jet substructure tagging techniques. The general method studied is to provide expert variables that augment inputs ("eXpert AUGmented" variables, or XAUG variables), then apply layerwise relevance propagation (LRP) to networks both with and without XAUG variables. The XAUG variables are concatenated with the intermediate layers after network-specific operations (such as convolution or recurrence), and used in the final layers of the network. The results of comparing networks with and without the addition of XAUG variables show that XAUG variables can be used to interpret classifier behavior, increase discrimination ability when combined with low-level features, and in some cases capture the behavior of the classifier completely. The LRP technique can be used to find relevant information the network is using, and when combined with the XAUG variables, can be used to rank features, allowing one to find a reduced set of features that capture part of the network performance. In the studies presented, adding XAUG variables to low-level DNNs increased the efficiency of classifiers by as much as 30-40\%. In addition to performance improvements, an approach to quantify numerical uncertainties in the training of these DNNs is presented.

    ↳ physics.data-ancs.LGhep-exhep-phJHEP(2021)·23 citations
21. 21*

    Chiral Perturbation for Large Momentum Effective Field Theory

    Wei-Yang Liu🇹🇼 · Jiunn-Wei Chen🇹🇼

    Large momentum effective field theory (LaMET) enables the extraction of parton distribution functions (PDFs) directly on a Euclidean lattice through a factorization theorem that relates the computed quasi-PDFs to PDFs. We apply chiral perturbation theory (ChPT) to LaMET to further separate soft scales, such as light quark masses and lattice size, to obtain leading model independent extrapolation formulas for extrapolations to physical quark masses and infinite volume. We find that the finite volume effect is reduced when the nucleon carries a finite momentum. For nucleon momentum greater than $1$ GeV and the lattice size $L$ and pion mass $m_{\pi }$ satisfying $m_{\pi }L\ge 3$, the finite volume effect is less than $1\%$ and is negligible for the current precision of lattice computations. This can be interpreted as a Lorentz contraction of the nucleon size in the $z$-direction which makes the lattice size effectively larger in that direction. We also find that the quark mass dependence in the infinite volume limit computed with non-zero nucleon momentum reproduces the previous result computed at zero momentum, as expected. Our approach can be generalized to other parton observables in LaMET straight forwardly.

    ↳ hep-lathep-phPRD(2021)·20 citations
22. 22*

    Gravitational and electromagnetic radiation from binary black holes with electric and magnetic charges: Elliptical orbits on a cone

    Lang Liu🇨🇳 · Øyvind Christiansen🇳🇴 · Wen-Hong Ruan🇨🇳 · Zong-Kuan Guo🇨🇳 · Rong-Gen Cai🇨🇳 · Sang Pyo Kim🇨🇳

    Extending the electromagnetic and gravitational radiations from binary black holes with electric and magnetic charges in circular orbits in Phys. Rev. D {\bf 102}, 103520 (2020), we calculate the total emission rates of energy and angular momentum due to gravitational and electromagnetic radiations from dyonic binary black holes in precessing elliptical orbits. It is shown that the emission rates of energy and angular momentum due to gravitational and electromagnetic radiations have the same dependence on the conic angle for different orbits. Moreover, we obtain the evolutions of orbits and find that a circular orbit remains circular while an elliptic orbit becomes quasi-circular due to electromagnetic and gravitational radiations. Using the evolution of orbits, we derive the waveform models for dyonic binary black hole inspirals and show the amplitudes of the gravitational waves for dyonic binary black hole inspirals differ from those for Schwarzschild binary black hole inspirals, which can be used to test electric and magnetic charges of black holes.

    ↳ gr-qchep-phEPJC(2021)·44 citations
23. 23*

    Axion Electrodynamics in Topological Materials

    Akihiko Sekine🇯🇵 · Kentaro Nomura🇯🇵

    One of the intriguing properties characteristic to three-dimensional topological materials is the topological magnetoelectric phenomena arising from a topological term called the $\theta$ term. Such magnetoelectric phenomena are often termed the axion electrodynamics, since the $\theta$ term has exactly the same form as the action describing the coupling between a hypothetical elementary particle, axion, and a photon. The axion was proposed about forty years ago to solve the so-called strong CP problem in quantum chromodynamics, and is now considered as a candidate for dark matter. In this tutorial, we overview theoretical and experimental studies on the axion electrodynamics in three-dimensional topological materials. Starting from the topological magnetoelectric effect in three-dimensional time-reversal invariant topological insulators, we describe the basic properties of static and dynamical axion insulators whose realizations require magnetic orderings. We also discuss the electromagnetic responses of Weyl semimetals with a focus on the chiral anomaly. We extend the concept of the axion electrodynamics in condensed matter to topological superconductors, whose responses to external fields can be described by a gravitational topological term analogous to the $\theta$ term.

    ↳ cond-mat.mes-hallcond-mat.mtrl-scicond-mat.str-elhep-phJ.Appl.Phys.(2021)·152 citations
24. 24*

    Quark-hadron crossover equations of state for neutron stars: constraining the chiral invariant mass in a parity doublet model

    Takuya Minamikawa🇯🇵 · Toru Kojo🇨🇳 · Masayasu Harada🇯🇵

    We construct an equation of state (EOS) for neutron stars by interpolating hadronic EOS at low density and quark EOS at high density. A hadronic model based on the parity doublet structure is used for hadronic matter and a quark model of Nambu--Jona-Lasinio type is for quark matter. We assume crossover between hadronic matter and quark matter in the the color-flavor locked phase. The nucleon mass of the parity doublet model has a mass associated with the chiral symmetry breaking, and a chiral invariant mass $m_0$ which is insensitive to the chiral condensate. The value of $m_0$ affects the nuclear EOSs at low density, and has strong correlations with the radii of neutron stars. Using the constraint to the radius obtained by LIGO-Virgo and NICER, we find that $m_0$ is restricted as $600\mathrm{MeV}\lesssim m_0\lesssim 900\mathrm{MeV}$.

    ↳ nucl-thastro-ph.HEhep-phPRC(2021)·66 citations
25. 25*

    Resurgent Analysis of Ward-Schwinger-Dyson Equations

    Marc P. Bellon🇫🇷 · Enrico I. Russo🇫🇷

    Building on our recent derivation of the Ward-Schwinger-Dyson equations for the cubic interaction model, we present here the first steps of their resurgent analysis. In our derivation of the WSD equations, we made sure that they had the properties of compatibility with the renormalisation group equations and independence from a regularisation procedure which was known to allow for the comparable studies in the Wess-Zumino model. The interactions between the transseries terms for the anomalous dimensions of the field and the vertex is at the origin of unexpected features, for which the effect of higher order corrections is not precisely known at this stage: we are only at the beginning of the journey to use resurgent methods to decipher non-perturbative effects in quantum field theory.

    ↳ hep-thhep-phmath-phmath.MPSIGMA(2021)·5 citations
26. 26*

    Gravity Gradient Noise from Asteroids

    Michael A. Fedderke🇺🇸 · Peter W. Graham🇺🇸 · Surjeet Rajendran🇺🇸

    The gravitational coupling of nearby massive bodies to test masses in a gravitational wave (GW) detector cannot be shielded, and gives rise to 'gravity gradient noise' (GGN) in the detector. In this paper we show that for any GW detector using local test masses in the Inner Solar System, the GGN from the motion of the field of $\sim 10^5$ Inner Solar System asteroids presents an irreducible noise floor for the detection of GW that rises exponentially at low frequencies. This severely limits prospects for GW detection using local test masses for frequencies $f_{\text{GW}}\lesssim (\text{few})\times 10^{-7}$Hz. At higher frequencies, we find that the asteroid GGN falls rapidly enough that detection may be possible; however, the incompleteness of existing asteroid catalogs with regard to small bodies makes this an open question around $f_{\text{GW}}\sim \mu$Hz, and further study is warranted. We show that a detector network placed in the Outer Solar System would not be overwhelmed by this noise above $\sim 10$nHz, and make comments on alternative approaches that could overcome the limitations of local test masses for GW detection in the $\sim 10$nHz-$\mu$Hz band.

    ↳ gr-qcastro-ph.EPastro-ph.HEastro-ph.IM+1PRD(2021)·24 citations
27. 27*

    Can Conformally Coupled Modified Gravity Solve The Hubble Tension?

    Tal Adi🇮🇱 · Ely D. Kovetz🇮🇱

    The discrepancy between early-Universe inferences and direct measurements of the Hubble constant, known as the Hubble tension, recently became a pressing subject in high precision cosmology. As a result, a large variety of theoretical models have been proposed to relieve this tension. In this work we analyze a conformally-coupled modified gravity (CCMG) model of an evolving gravitational constant due to the coupling of a scalar field to the Ricci scalar, which becomes active around matter-radiation equality, as required for solutions to the Hubble tension based on increasing the sound horizon at recombination. The model is theoretically advantageous as it has only one free parameter in addition to the baseline $\Lambda$CDM ones. Inspired by similar recent analyses of so-called early-dark-energy models, we constrain the CCMG model using a combination of early and late-Universe cosmological datasets. In addition to the Planck 2018 cosmic microwave background (CMB) anisotropies and weak lensing measurements, baryon acoustic oscillations and the Supernova H0 for the Equation of State datasets, we also use large-scale structure (LSS) datasets such as the Dark Energy Survey year 1 and the full-shape power spectrum likelihood from the Baryon Oscillation Spectroscopic Survey, including its recent analysis using effective field theory, to check the effect of the CCMG model on the (milder) S8 tension between the CMB and LSS. We find that the CCMG model can slightly relax the Hubble tension, with $H_0=69.6\pm 1.6$ km/s/Mpc at 95% CL, while barely affecting the S8 tension. However, current data does not exhibit strong preference for CCMG over the standard cosmological model. Lastly, we show that the planned CMB-S4 experiment will have the sensitivity required to distinguish between the CCMG model and the more general class of models involving an evolving gravitational constant.

    ↳ astro-ph.COhep-phhep-thPRD(2021)·91 citations
28. 28*

    Transseries for causal diffusive systems

    Michal P. Heller🇩🇪 · Alexandre Serantes🇵🇱 · Michał Spaliński🇵🇱 · Viktor Svensson🇩🇪 · Benjamin Withers🇬🇧

    The large proper-time behaviour of expanding boost-invariant fluids has provided many crucial insights into quark-gluon plasma dynamics. Here we formulate and explore the late-time behaviour of nonequilibrium dynamics at the level of linearized perturbations of equilibrium, but without any special symmetry assumptions. We introduce a useful quantitative approximation scheme in which hydrodynamic modes appear as perturbative contributions while transients are nonperturbative. In this way, solutions are naturally organized into transseries as they are in the case of boost-invariant flows. We focus our attention on the ubiquitous telegrapher's equation, the simplest example of a causal theory with a hydrodynamic sector. In position space we uncover novel transient contributions as well as Stokes phenomena which change the structure of the transseries based on the spacetime region or the choice of initial data.

    ↳ hep-thcond-mat.str-elhep-phnucl-th+1JHEP(2021)·8 citations
29. 29*

    The Impact of New d(p,\gamma)He3 Rates on Big Bang Nucleosynthesis

    Tsung-Han Yeh🇺🇸 · Keith A. Olive🇺🇸 · Brian D. Fields🇺🇸

    We consider the effect on Big Bang Nucleosynthesis (BBN) of new measurements of the $d(p,\gamma ){}^3$He cross section by the LUNA Collaboration. These have an important effect on the primordial abundance of D/H which is also sensitive to the baryon density at the time of BBN. We have re-evaluated the thermal rate for this reaction, using a world average of cross section data, which we describe with model-independent polynomials; our results are in good agreement with a similar analysis by LUNA. We then perform a full likelihood analysis combining BBN and Planck cosmic microwave background (CMB) likelihood chains using the new rate combined with previous measurements and compare with the results using previous rates. Concordance between BBN and CMB measurements of the anisotropy spectrum using the old rates was excellent. The predicted deuterium abundance at the Planck value of the baryon density was $(D/H{)}_{\mathrm{BBN}+\mathrm{CMB}}^{\mathrm{old}}=(2.57\pm 0.13)\times 10^{-5}$ which can be compared with the value determined from quasar absorption systems $(D/H{)}_{\mathrm{obs}}=(2.55\pm 0.03)\times 10^{-5}$. Using the new rates we find $(D/H{)}_{\mathrm{BBN}+\mathrm{CMB}}=(2.51\pm 0.11)\times 10^{-5}$. We thus find consistency among BBN theory, deuterium and ${}^4$He observations, and the CMB, when using reaction rates fit in our data-driven approach. We also find that the new reaction data tightens the constraints on the number of relativistic degrees of freedom during BBN, giving the effective number of light neutrino species $N_{\nu }=2.880\pm 0.144$ in good agreement with the Standard Model of particle physics. Finally, we note that the observed deuterium abundance continues to be more precise than the BBN+CMB prediction, whose error budget is now dominated by $d(d,n){}^3$He and $d(d,p){}^3\mathrm{H}$.

    ↳ astro-ph.COhep-phnucl-exJCAP(2021)·114 citations
30. 30*

    Simulation-efficient marginal posterior estimation with swyft: stop wasting your precious time

    Benjamin Kurt Miller🇳🇱 · Alex Cole🇳🇱 · Gilles Louppe🇧🇪 · Christoph Weniger🇳🇱

    We present algorithms (a) for nested neural likelihood-to-evidence ratio estimation, and (b) for simulation reuse via an inhomogeneous Poisson point process cache of parameters and corresponding simulations. Together, these algorithms enable automatic and extremely simulator efficient estimation of marginal and joint posteriors. The algorithms are applicable to a wide range of physics and astronomy problems and typically offer an order of magnitude better simulator efficiency than traditional likelihood-based sampling methods. Our approach is an example of likelihood-free inference, thus it is also applicable to simulators which do not offer a tractable likelihood function. Simulator runs are never rejected and can be automatically reused in future analysis. As functional prototype implementation we provide the open-source software package swyft.

    ↳ astro-ph.IMastro-ph.COcs.LGhep-ph27 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.