Wed·May 11, 2022Wednesday·May 11, 2022

1. 01*

   Soft Integrals and Soft Anomalous Dimensions at N${}^3$LO and Beyond

   Claude Duhr🇩🇪 · Bernhard Mistlberger🇺🇸 · Gherardo Vita🇺🇸

   We calculate soft phase-space and loop master integrals tor the computation of color-singlet cross sections through N${}^3$LO in perturbative QCD. Our results are functions of homogeneous transcendental weight and include the first nine terms in the expansion in the dimensional regulator $ϵ$. We discuss the application of our results to the computation of deeply-inelastic scattering and $e^{+}{e}^{-}$ annihilation processes. We use these results to compute the perturbative coefficient functions for the Drell-Yan and gluon-fusion Higgs boson production cross sections to higher orders in $ϵ$ through N${}^3$LO in QCD in the limit where only soft partons are produced on top of the colorless final state. Furthermore, we extract the anomalous dimension of the inclusive threshold soft function and of the $N$-Jettiness beam and jet functions to N${}^4$LO in perturbative QCD.

   hep-phhep-thJHEP(2022)·46 citations
2. 02*

   Asymmetric particle-antiparticle Dirac equation: first quantization

   Gustavo Rigolin🇧🇷

   We derive a Dirac-like equation, the asymmetric Dirac equation, where particles and antiparticles sharing the same wave number have different energies and momenta. We show that this equation is Lorentz covariant under proper Lorentz transformations (boosts and spatial rotations) and also determine the corresponding transformation law for its wave function. We obtain a formal connection between the asymmetric Dirac equation and the standard Dirac equation and we show that by properly adjusting the free parameters of the present wave equation we can make it reproduce the predictions of the usual Dirac equation. We show that the rest mass of a particle in the theoretical framework of the asymmetric Dirac equation is a function of a set of four parameters, which are relativistic invariants under proper Lorentz transformations. These four parameters are the analog to the mass that appears in the standard Dirac equation. We prove that in order to guarantee the covariance of the asymmetric Dirac equation under parity and time reversal operations (improper Lorentz transformations) as well as under the charge conjugation operation, these four parameters change sign in exactly the same way as the four components of a four-vector. The mass, though, being a function of the square of those parameters remains an invariant. We also extensively study the free particle plane wave solutions to the asymmetric Dirac equation and derive its energy, helicity, and spin projection operators as well as several Gordon's identities. The hydrogen atom is solved in the present context after applying the minimal coupling prescription to the asymmetric Dirac equation, which also allows us to appropriately obtain its non-relativistic limit.

   hep-phhep-thquant-phJ.Phys.G(2023)·2 citations
3. 03*

   Unveiling Nucleon 3D Chiral-Odd Structure with Jet Axes

   Wai Kin Lai🇨🇳 · Xiaohui Liu🇨🇳 · Manman Wang🇨🇳 · Hongxi Xing🇨🇳

   We reinterpret jet clustering as an axis-finding procedure which, along with the proton beam, defines the virtual-photon transverse momentum $q_T$ in deep inelastic scattering (DIS). In this way, we are able to probe the nucleon intrinsic structure using jet axes in a fully inclusive manner, similar to the Drell-Yan process. We present the complete list of azimuthal asymmetries and the associated factorization formulae at leading power for deep-inelastic scattering of a nucleon. The factorization formulae involve both the conventional time-reversal-even (T-even) jet function and the T-odd one, which have access to all transverse-momentum-dependent parton distribution functions (TMD PDFs) at leading twist. Since the factorization holds as long as $q_T\ll Q$, where $Q$ is the photon virtuality, the jet-axis probe into the nucleon structure should be feasible for machines with relatively low energies such as the Electron-Ion Collider in China (EicC). We show that, within the winner-take-all (WTA) axis-finding scheme, the coupling between the T-odd jet function and the quark transversity or the Boer-Mulders function could induce sizable azimuthal asymmetries at the EicC, the EIC and HERA. We also give predictions for the azimuthal asymmetry of back-to-back dijet production in $e^{+}{e}^{-}$ annihilation at Belle and other energies.

   hep-phhep-exnucl-ex16 citations
4. 04*

   Speed of sound in QCD matter

   Wei-bo He🇨🇳 · Guo-yun Shao🇨🇳 · Xue-yan Gao🇨🇳 · Xin-ran Yang🇨🇳 · Chong-long Xie🇨🇳

   We systematically investigate the speed of sound in QCD matter under different conditions in the grand canonical ensemble within the Polyakov loop improved Nambu--Jona-Lasinio (PNJL) model. The numerical results indicate that the dependence of speed of sound on parameters like temperature and chemical potential can be indicative of QCD phase transition. Some new features of speed of sound are discovered, for instance, the hierarchy of sound velocity for $u(d)$ and $s$ quark at low temperature with the increasing chemical potential and the squared sound velocity approaching to almost zero in the critical region. We also formulate the relations between differently defined sound velocity using the fundamental thermodynamic relations. Some conclusions derived are useful for hydrodynamics simulation and calculation of transport coefficient of bulk viscosity.

   hep-phPRD(2022)·28 citations
5. 05*

   B $-$ L genesis by sliding inflaton

   M. Yoshimura🇯🇵

   We propose a new mechanism of lepton (L) number asymmetry generation, hence offer an explanation of matter-antimatter imbalance when a significant amount of baryon number is later transformed from this L-number by known electroweak sphaleron mediated process. The basic theoretical framework is a recently proposed multiple scalar-tensor gravity that dynamically solves the cosmological constant problem. The L-asymmetry generation in one of two proposed scenarios is triggered by dynamical relaxation of scalar inflaton field towards the zero cosmological constant. CPT violation (C= charge conjugation, P = parity operation, T= time reversal) in the presence of a chemical potential gives the necessary time arrow, and lepton number violating scattering in cosmic thermal medium generates a net cosmological L-number via resonance formation. Another scenario is L-asymmetry generation from evaporating primordial black holes. These proposed mechanisms do not require CP violating phases in physics beyond the standard model: the new required physics is existence of heavy Majorana leptons of masses $10^{15}\sim 10^{17}$ GeV that realizes the seesaw mechanism. We identify the cosmological epoch of lepto-genesis in two scenarios, which may give the right amount of observed baryon to entropy ratio. It might even be possible to experimentally determine microscopic physics parameter, masses of three heavy Majorana leptons by observing astrophysical footprints of primordial black hole evaporation at specified hole masses.

   hep-phastro-ph.COgr-qchep-thJCAP(2022)·2 citations
6. 06*

   Transverse momentum structure of proton within the basis light-front quantization framework

   Zhi Hu🇨🇳 · Siqi Xu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

   We obtain the leading-twist valence quark transverse-momentum-dependent parton distribution functions (TMD PDFs) for the proton within the basis light-front quantization (BLFQ) framework. Our results are consistent with lattice QCD calculations and our previous results for the collinear limit. We also obtain consistency with the Soffer-type bounds. Within our approach, we find that six T-even TMDs in the leading twist are all independent of each other, and previously found model-dependent relations do not hold. This is a promising sign that our results are representative of future, more extensive treatments of QCD. Furthermore, we obtain a non-trivial $x$-dependence of the $⟨(p^{\perp }{)}^2⟩$ and some consistency with the Gaussian ansatz but only in the small $(p^{\perp }{)}^2$ region. Those features suggest our results may be a useful alternative in future experimental extractions.

   hep-phPLB(2022)·34 citations
7. 07*

   Mass dimension one fermions: Constructing darkness

   Dharam Vir Ahluwalia🇮🇳 · Julio M. Hoff da Silva🇧🇷 · Cheng-Yang Lee🇨🇳 · Yu-Xiao Liu🇨🇳 · Saulo H. Pereira🇧🇷 · Masoumeh Moazzen Sorkhi🇮🇷

   Let $\Theta$ be the Wigner time reversal operator for spin half and let $\varphi$ be a Weyl spinor. Then, for a left-transforming $\varphi$, the construct ${\zeta }_{\lambda }\Theta {\varphi }^{\ast }$ yields a right-transforming spinor. If instead, $\varphi$ is a right-transforming spinor, then the construct ${\zeta }_{\rho }\Theta {\varphi }^{\ast }$ results in a left-transforming spinor (${\zeta }_{\lambda ,\rho }$ are phase factors). This allows us to introduce two sets of four-component spinors. Setting ${\zeta }_{\lambda }$ and ${\zeta }_{\rho }$ to $\pm i$ render all eight spinors as eigenspinor of the charge conjugation operator~$\mathcal{C}$ (called ELKO). This allows us to introduce two quantum fields. A calculation of the vacuum expectation value of the time-ordered product of the fields and their adjoints reveals the mass dimension of the fields to be one. Both fields are local in the canonical sense of quantum field theory. Interestingly, one of the fields is fermionic and the other bosonic. The mass dimension of the introduced fermionic fields and the matter fields of the Standard Model carry an intrinsic mismatch. As such, they provide natural darkness for the new fields with respect to the Standard Model doublets. The statistics and locality are controlled by a set of phases. These are explicitly given. Then we observe that in $p_{\mu }{p}^{\mu }=m^2$, Dirac took the simplest square root of the $4\times 4$ identity matrix $I$ (in $I\times m^2$, while introducing ${\gamma }_{\mu }{p}^{\mu }$ as the square root of the left hand side of the dispersion relation), and as such he implicitly ignored the remaining fifteen. When we examine the remaining roots, we obtain additional bosonic and fermionic dark matter candidates of spin half. We point out that by early nineteen seventies, Dirac had suspected the existence of spin half bosons, in the same space as his fermions. Abstract truncated.

   hep-phgr-qchep-thPhys.Rept.(2022)·49 citations
8. 08*

   The role of meson interactions in the $D_s^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}\eta$ decay

   Jing Song🇨🇳 · A. Feijoo🇪🇸 · E.Oset🇪🇸

   We perform a theoretical study of the $D_s^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}\eta$ decay. We look first at the basic $D_s^{+}$ decay at the quark level from external and internal emission. Then hadronize a pair or two pairs of $q\bar{q}$ states to have mesons at the end. Posteriorly the pairs of mesons are allowed to undergo final state interaction, by means of which the $a_0(980)$, $f_0(980)$, $a_1(1260)$, and $b_1(1235)$ resonances are dynamically generated. The $G$-parity is used as a filter of the possible channels, and from those with negative $G$-parity only the ones that can lead to ${\pi }^{+}{\pi }^{+}{\pi }^{-}\eta$ at the final state are kept. Using transition amplitudes from the chiral unitary approach that generates these resonances, and a few free parameters, we obtain a fair reproduction of the six mass distributions reported in BESIII experiment.

   hep-phPRD(2022)·10 citations
9. 09*

   Deconfinement phase transition and quark condensate in compact stars

   Hao-Miao Jin🇨🇳 · Cheng-Jun Xia🇨🇳 · Ting-Ting Sun🇨🇳 · Guang-Xiong Peng🇨🇳

   We investigate systematically the possible deconfinement phase transition from nuclear matter to quark matter in compact stars. The properties of nuclear matter are fixed by expanding its binding energy to the order of ${\rho }^3$, while those of quark matter are predicted by an equivparticle model. The Maxwell construction is then applied for the quark-hadron mixed phase. By confronting compact star structures with pulsar observations, we obtain several EOSs that are compatible with the latest observations while supporting quark cores inside the most massive stars. It is found that the quark core is rather small and does not emerge for compact stars with $M\lesssim 2M_{\odot }$. The in-medium quark condensate of the stellar matter in those stars are then extracted within the framework of an equivparticle model, which decreases nonlinearly with density. At larger densities with pure quark matter, the quark condensate is still large and does not necessary decrease with density, indicating significant nonperturbative contributions within the density regions covered by compact stars.

   hep-phnucl-th2 citations
10. 10*

    Heavier $W$ boson, dark matter and gravitational waves from strings in an $SO(10)$ axion model

    George Lazarides🇬🇷 · Rinku Maji🇮🇳 · Rishav Roshan🇰🇷 · Qaisar Shafi🇺🇸

    Inspired by the recent determination of the $W$-boson mass by the CDF collaboration, we revisit an $SO(10)$ axion model in which a scalar $SU(2{)}_L$ triplet field with zero hypercharge is known to acquire a non-zero VEV through its mixing with the Standard Model Higgs doublet. The triplet VEV provides a sizable contribution to the $W$ mass, which helps in significantly lowering the $7\sigma$ discrepancy between the Standard Model prediction and the higher CDF value for $m_W$. We show that the relatively light triplet mass ($\sim (1-50)$ TeV) is compatible with gauge coupling unification and observable proton decay. An unbroken $Z_2$ gauge symmetry, coupled with the presence of two fermionic $10$-plets required to resolve the axion domain wall problem, means that both axions and a stable intermediate mass ($\sim 10^9-10^{10}$ GeV) fermion are plausible dark matter candidates. We also display the gravitational wave spectrum from the intermediate scale topologically stable cosmic strings predicted by the model.

    hep-phastro-ph.COPRD(2022)·35 citations
11. 11*

    Color dipole cross section in the DGLAP improved saturation model

    G.R.Boroun🇮🇷

    We show that the geometric scaling of the dipole cross section can be explained using standard DGLAP perturbative evolution. The DGLAP improved saturation model due to the Laplace transforms method is considered at LO and NNLO approximations from the experimental data by relying on a Froissart-bounded parametrization of $F_2(x,Q^2)$. These results are comparable with Golec-Biernat-W$\ddot{\mathrm{u}}$sthoff (GBW) model in a wide kinematic region $r{Q}_s$ which takes into account charm mass. The successful description of ${\sigma }_{\mathrm{dip}}(x,r)/{\sigma }_0$ and ${\sigma }_{\mathrm{dip}}(r{Q}_s)/{\sigma }_0$ are presented.

    hep-phEPJC(2022)·6 citations
12. 12*

    $SU(5)$ grand unification and $W$-boson mass

    Goran Senjanović🇩🇪 · Michael Zantedeschi🇩🇪

    A realistic extension of the minimal $SU(5)$ theory consisting of the addition of an adjoint fermion is known to predict light real fermion and scalar weak triplets, potentially accessible at the LHC. These particles, in addition to playing a key role in gauge coupling unification, have profound phenomenological implications. The fermion triplet, that through the seesaw mechanism offers a testable origin of neutrino mass, has been already extensively discussed. The scalar triplet develops a vacuum expectation value that modifies the $W$-boson mass. We show that its low-energy effective theory is remarkably predictive: in the leading approximation, all the relevant physical processes involving the scalar triplet depend only on its mass and the deviation from the Standard Model $W$-mass value.

    hep-phPLB(2023)·35 citations
13. 13*

    Axial-vector $D_1$ hadrons in $D^{\ast }\pi$ scattering from QCD

    Nicolas Lang🇮🇪 · David J. Wilson🇬🇧

    We present $I=1/2$ $D^{\ast }\pi$ scattering amplitudes from lattice QCD and determine two low-lying $J^P=1^{+}$ axial-vector $D_1$ states and a $J^P=2^{+}$ tensor $D_2^{\ast }$. Computing finite-volume spectra at a light-quark mass corresponding to $m_{\pi }=391$ MeV, for the first time, we are able to constrain coupled $J^P=1^{+}$ $D^{\ast }\pi$ amplitudes with ${}^{2S+1}{\ell }_J={}^3{S}_1$ and ${}^3{D}_1$ as well as coupled $J^P=2^{+}$ $D\pi {\{}^1{D}_2\}$ and $D^{\ast }\pi {\{}^3{D}_2\}$ amplitudes via Lüscher's quantization condition. Analyzing the scattering amplitudes for poles we find a near-threshold bound state, producing a broad feature in $D^{\ast }\pi {\{}^3{S}_1\}$. A narrow bump occurs in $D^{\ast }\pi {\{}^3{D}_1\}$ due to a $D_1$ resonance. A single resonance is found in $J^P=2^{+}$ coupled to $D\pi$ and $D^{\ast }\pi$. A relatively low mass and large coupling is found for the lightest $D_1$, suggestive of a state that will evolve into a broad resonance as the light quark mass is reduced. An earlier calculation of the scalar $D_0^{\ast }$ using the same light-quark mass enables comparisons to the heavy-quark limit.

    hep-phhep-latPRL(2022)·27 citations
14. 14*

    The $\rho$ parameter and the CDF W-mass anomaly: observations on the role of scalar triplets

    Rituparna Ghosh🇮🇳 · Biswarup Mukhopadhyaya🇮🇳 · Utpal Sarkar🇮🇳

    The $\rho$-parameter, together with the W-and Z-masses, acts as Occam's razor on extensions of the electroweak symmetry breaking sectors. We apply this to non-doublet Higgs scenarios, by examining the CDF- $II$ claim on the W-boson mass. Suspending any judgement on the CDF claim, we show that in general, if one works at the tree level, theoretical models which predict $\rho =1$ at the tree-level are inconsistent with the CDF claims at 4-6 standard deviations if one confines oneself to the existing Z-boson mass, and the earlier $M_W$ value from either the global fit or the ATLAS data. We take some well-motivated scenarios containing one or more scalar SU(2) triplets in addition to the usual doublet, and show that, both a scenario including a complex scalar triplet and one with a complex as well as a real triplet (the Georgi-Machacek model) can be made consistent with the new data, where a small splitting between the complex and the real triplet vacuum expectation values is required in the second scenario. We will explore the consequences of this splitting, either at tree level or via incalculable new physics contribution to $M_W$, and indicate, as illustrations its implications in $H^{\pm }{W}^{\mp }Z$ type interaction vertices.

    hep-phJ.Phys.G(2023)·21 citations
15. 15*

    Radiative corrections to neutron and nuclear $\beta$-decays: a serious kinematics problem in the literature

    Ferenc Glück🇩🇪

    We report a serious kinematics problem in the bremsstrahlung photon part of the order-$\alpha$ outer (model independent) radiative correction calculations for those neutron (and nuclear beta) decay observables (like electron-neutrino correlation parameter measurement) where the proton (recoil particle) is detected. The so-called neutrino-type radiative correction calculations, which fix the neutrino direction in the bremsstrahlung photon integrals, use 3-body decay kinematics to connect the unobserved neutrino direction with the observed electron and proton (recoil particle) momenta. But the presence of the bremsstrahlung photon changes the kinematics from 3-body to 4-body one, and the accurate information about the recoil particle momentum is lost due to the integration with respect to the photon momentum. Therefore the application of the abovementioned 3-body decay kinematics connection for the radiative correction calculations, rather prevalent in the literature, is not acceptable. We show that the correct, so-called recoil-type radiative correction calculations, which fix the proton (recoil particle) momentum instead of the neutrino direction and use rather involved analytical, semianalytical or Monte Carlo bremsstrahlung integration methods, result usually in much larger corrections than the incorrect neutrino-type analytical methods.

    hep-phJHEP(2023)·13 citations
16. 16*

    Bias and Priors in Machine Learning Calibrations for High Energy Physics

    Rikab Gambhir🇺🇸 · Benjamin Nachman🇺🇸 · Jesse Thaler🇺🇸

    Machine learning offers an exciting opportunity to improve the calibration of nearly all reconstructed objects in high-energy physics detectors. However, machine learning approaches often depend on the spectra of examples used during training, an issue known as prior dependence. This is an undesirable property of a calibration, which needs to be applicable in a variety of environments. The purpose of this paper is to explicitly highlight the prior dependence of some machine learning-based calibration strategies. We demonstrate how some recent proposals for both simulation-based and data-based calibrations inherit properties of the sample used for training, which can result in biases for downstream analyses. In the case of simulation-based calibration, we argue that our recently proposed Gaussian Ansatz approach can avoid some of the pitfalls of prior dependence, whereas prior-independent data-based calibration remains an open problem.

    hep-phhep-exphysics.data-anstat.MLPRD(2022)·12 citations
17. 17*

    Instantons, renormalons and the theta angle in integrable sigma models

    Marcos Marino🇨🇭 · Ramon Miravitllas🇨🇭 · Tomas Reis🇨🇭

    Some sigma models which admit a theta angle are integrable at both $\vartheta =0$ and $\vartheta =\pi$. This includes the well-known $O(3)$ sigma model and two families of coset sigma models studied by Fendley. We consider the ground state energy of these models in the presence of a magnetic field, which can be computed with the Bethe ansatz. We obtain explicit results for its non-perturbative corrections and we study the effect of the theta angle on them. We show that imaginary, exponentially small corrections due to renormalons remain unchanged, while instanton corrections change sign, as expected. We find in addition corrections due to renormalons which also change sign as we turn on the theta angle. Based on these results we present an explicit non-perturbative formula for the topological susceptibility of the $O(3)$ sigma model in the presence of a magnetic field, in the weak coupling limit.

    ↳ hep-thhep-lathep-phmath-ph+1SciPost Phys.(2023)·20 citations
18. 18*

    Front Propagation from Radiative Sources

    Theodore Steele🇬🇧 · Kinwah Wu🇬🇧

    Fronts are regions of transition from one state to another in a medium. They are present in many areas of science and applied mathematics, and modelling them and their evolution is often an effective way of treating the underlying phenomena responsible for them. In this paper, we propose a new approach to modelling front propagation, which characterises the evolution of structures surrounding radiative sources. This approach is generic and has a wide range of applications, particularly when dealing with the propagation of phase or state transitions in media surrounding radiation emitting objects. As an illustration, we show an application in modelling the propagation of ionisation fronts around early stars during the cosmological Epoch of Reionisation (EoR) and show that the results are consistent with those of existing equations but provide much richer sources of information.

    ↳ astro-ph.HEhep-phphysics.comp-ph0 citations
19. 19*

    A Feynman integral depending on two elliptic curves

    Hildegard Müller🇩🇪 · Stefan Weinzierl🇩🇪

    We study a two-loop four-point function with one internal mass. This Feynman integral is one of the simplest Feynman integrals depending on two elliptic curves. We transform the associated differential equation into an $\epsilon$-form. We study the entries of the differential equation, and in particular the entries which depend on both elliptic curves.

    ↳ hep-thhep-phJHEP(2022)·38 citations
20. 20*

    Quantum phase transitions in a bidimensional $O(N)\times {\mathbb{Z}}_2$ scalar field model

    Gustavo O. Heymans🇧🇷 · Marcus Benghi Pinto🇧🇷 · Rudnei O. Ramos🇧🇷

    We analyze the possible quantum phase transition patterns occurring within the $O(N)\times {\mathbb{Z}}_2$ scalar multi-field model at vanishing temperatures in $(1+1)$-dimensions. The physical masses associated with the two coupled scalar sectors are evaluated using the loop approximation up to second order. We observe that in the strong coupling regime, the breaking $O(N)\times {\mathbb{Z}}_2\to O(N)$, which is allowed by the Mermin-Wagner-Hohenberg-Coleman theorem, can take place through a second-order phase transition. In order to satisfy this no-go theorem, the $O(N)$ sector must have a finite mass gap for all coupling values, such that conformality is never attained, in opposition to what happens in the simpler ${\mathbb{Z}}_2$ version. Our evaluations also show that the sign of the interaction between the two different fields alters the transition pattern in a significant way. These results may be relevant to describe the quantum phase transitions taking place in cold linear systems with competing order parameters. At the same time the super-renormalizable model proposed here can turn out to be useful as a prototype to test resummation techniques as well as non-perturbative methods.

    ↳ hep-thcond-mat.softhep-phJHEP(2022)·6 citations
21. 21*

    Transport Equation for Small Systems and Nonadditive Entropy

    Eugenio Megias🇪🇸 · Jose A. S. Lima🇧🇷 · Airton Deppman🇧🇷

    The nonadditive entropy introduced by Tsallis in 1988 has been used in different fields and generalizes the Boltzmann entropy extending the possibilities of application of the statistical methods developed in the context of Mechanics. Here we investigate one of the last points of the theory that still are under discussion: the source term of the nonextensive transport equation. Based on a simple system, we show that the nonadditivity is a direct consequence of the phase space topology, and derive the source term that leads to the nonextensive transport equation.

    ↳ cond-mat.stat-mechhep-phnucl-thMathematics(2022)·5 citations
22. 22*

    Constraining ultralight bosonic dark matter with Keck observations of S2's orbit and kinematics

    Guan-Wen Yuan🇨🇳 · Zhao-Qiang Shen🇨🇳 · Yue-Lin Sming Tsai🇨🇳 · Qiang Yuan🇨🇳 · Yi-Zhong Fan🇨🇳

    Ultralight bosonic dark matter is expected to be able to form a cloud surrounding the supermassive black hole (SMBH) in the Galactic center. With increasing precision of the observations of the stellar kinematics around the SMBH, tiny effects from such a dark matter cloud, including its gravitational perturbation and the direct coupling with the ordinary matter may be detectable. In this work, we search for possible evidence of the scalar cloud using accurate orbital measurements of the S2 star around Sgr~A*. We solve the first order Post-Newtonian equation, considering simultaneously the extended mass distribution of the scalar cloud and the frequency shift induced by the additional coupling via Higgs portal or photon portal interaction. Furthermore, we also investigate the impact of an astrophysical power-law component from the gas and stellar remnants. We find that the astrometric and spectroscopic data of the S2 star are well consistent with the scenario of a point-like mass of Sgr~A*. We thus derive upper limits of the coupling of the new interaction and the extended mass, with and without the contribution from the astrophysical component. The limits of the Higgs/photon coupling and the extended mass of the scalar cloud are the most stringent ones for the scalar mass window between $3.2\times 10^{-19}$~eV and $1.6\times 10^{-18}$~eV.

    ↳ astro-ph.HEastro-ph.COastro-ph.SRgr-qc+1PRD(2022)·30 citations
23. 23*

    Leading singularities in higher-derivative Yang-Mills theory and quadratic gravity

    Gabriel Menezes🇧🇷

    In this work we explore general leading singularities of one-loop amplitudes in higher-derivative Yang-Mills and quadratic gravity. These theories are known to possess propagators which contain quadratic and quartic momentum dependence, which leads to the presence of an unstable ghostlike resonance. However, unitarity cuts are not to be taken through unstable particles and therefore unitarity is still satisfied. On the other hand, this could engender issues when calculating leading singularities which are generalizations of unitarity cuts. Nevertheless, we will show with explicit examples how leading singularities are still well defined and accordingly they are able to capture relevant information on the analytic structure of amplitudes in such higher-derivative theories. We discuss some simple one-loop amplitudes which clarify these features.

    ↳ hep-thgr-qchep-phUniverse(2022)·7 citations
24. 24*

    Faint light of old neutron stars and detectability at the James Webb Space Telescope

    Shiuli Chatterjee🇮🇳 · Raghuveer Garani🇮🇹 · Rajeev Kumar Jain🇮🇳 · Brijesh Kanodia🇮🇳 · M. S. N. Kumar🇵🇹 · Sudhir K. Vempati🇮🇳

    Isolated ideal neutron stars (NS) of age $>10^9$ yrs exhaust thermal and rotational energies and cool down to temperatures below $\mathcal{O}(100)$ K. Accretion of particle dark matter (DM) by such NS can heat them up through kinetic and annihilation processes. This increases the NS surface temperature to a maximum of $\sim 2550$ K in the best case scenario. The maximum accretion rate depends on the DM ambient density and velocity dispersion, and on the NS equation of state and their velocity distributions. Upon scanning over these variables, we find that the effective surface temperature varies at most by $\sim 40\%$. Black body spectrum of such warm NS peak at near infrared wavelengths with magnitudes in the range potentially detectable by the James Webb Space Telescope (JWST). Using the JWST exposure time calculator, we demonstrate that NS with surface temperatures $\gtrsim 2400$ K, located at a distance of 10\,pc can be detected through the F150W2 (F322W2) filters of the NIRCAM instrument at SNR\,$\gtrsim 10$ (5) within 24 hours of exposure time. Independently of DM, an observation of NS with surface temperatures $\gtrsim 2500$ K will be a formative step towards testing the minimal cooling paradigm during late evolutionary stages.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2023)·40 citations
25. 25*

    Power spectrum of domain-wall network and its implications for isotropic and anisotropic cosmic birefringence

    Naoya Kitajima🇯🇵 · Fumiaki Kozai🇯🇵 · Fuminobu Takahashi🇯🇵 · Wen Yin🇯🇵

    Recently, based on a novel analysis of the Planck satellite data, a hint of a uniform rotation of the polarization of cosmic microwave background photons, called isotropic cosmic birefringence, has been reported. The suggested rotation angle of polarization of about $0.2-0.4$ degrees strongly suggests that it is determined by the fine structure constant, which can be naturally explained over a very wide parameter range by the domain walls of axion-like particles. Interestingly, the axion-like particle domain walls predict not only isotropic cosmic birefringence but also anisotropic one that reflects the spatial distribution of the axion-like particle field on the last scattering surface. In this Letter, we perform lattice simulations of the formation and evolution of domain walls in the expanding universe and obtain for the first time the two-point correlation function and power spectrum of the scalar field that constitutes the domain walls. We find that while the power spectrum is generally consistent with analytical predictions based on random wall distributions, there is a predominant excess on the scale corresponding to the Hubble radius. Applying our results to the anisotropic cosmic birefringence, we predict the power spectrum of the rotation angles induced by the axion-like particle domain walls and show that it is within the reach of future observations of the cosmic microwave background.

    ↳ astro-ph.COhep-exhep-lathep-phJCAP(2022)·52 citations
26. 26*

    Non-invertible Global Symmetries in the Standard Model

    Yichul Choi🇺🇸 · Ho Tat Lam🇺🇸 · Shu-Heng Shao🇺🇸

    We identify infinitely many non-invertible generalized global symmetries in QED and QCD for the real world in the massless limit. In QED, while there is no conserved Noether current for the $U(1{)}_{\text{A}}$ axial symmetry because of the ABJ anomaly, for every rational angle $2\pi p/N$, we construct a conserved and gauge-invariant topological symmetry operator. Intuitively, it is a composition of the axial rotation and a fractional quantum Hall state coupled to the electromagnetic $U(1)$ gauge field. These conserved symmetry operators do not obey a group multiplication law, but a non-invertible fusion algebra over TQFT coefficients. They act invertibly on all local operators as axial rotations, but non-invertibly on the 't Hooft lines. These non-invertible symmetries lead to selection rules, which are consistent with the scattering amplitudes in QED. We further generalize our construction to QCD, and show that the coupling ${\pi }^{0}F\wedge F$ in the effective pion Lagrangian is necessary to match these non-invertible symmetries in the UV. Therefore, the conventional argument for the neutral pion decay using the ABJ anomaly is now rephrased as a matching condition of a generalized global symmetry.

    ↳ hep-thcond-mat.str-elhep-phPRL(2022)·296 citations

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