Wed·Aug 4, 2021Wednesday·August 4, 2021

1. 01*

   Observable flavor violation from spontaneous lepton number breaking

   Pablo Escribano🇪🇸 · Martin Hirsch🇪🇸 · Jacopo Nava🇪🇸 · Avelino Vicente🇪🇸

   We propose a simple model of spontaneous lepton number violation with potentially large flavor violating decays, including the possibility that majoron emitting decays, such as $\mu \to eJ$, saturate the experimental bounds. In this model the majoron is a singlet-doublet admixture. It generates a type-I seesaw for neutrino masses and contains also a vector-like lepton. As a by-product, the model can explain the anomalous $(g-2{)}_{\mu }$ in parts of its parameter space, where one expects that the branching ratio of the Higgs to muons is changed with respect to Standard Model expectations. However, the explanation of the muon $g-2$ anomaly would lead to tension with recent astrophysical bounds on the majoron coupling to muons.

   hep-phJHEP(2022)·16 citations
2. 02*

   Linearized dispersion relations in viscous relativistic hydrodynamics

   Guillermo Perna🇦🇷 · Esteban Calzetta🇦🇷

   We compute the dispersion relations for scalar, vector and tensor modes of a viscous relativistic fluid, linearized around an equilibrium solution, for a divergence type theory (which, in the linearized theory, includes Israel-Stewart and anisotropic hydrodynamics as particular cases) and contrast them to the corresponding results derived from kinetic theory under the relaxation time approximation, and from causal first order theories. We conclude that all approaches give similar dynamics for the scalar and vector modes, while the particular divergence type theory presented here also contains propagating damped tensor waves, in agreement with kinetic theory. Non hydrodynamic tensor modes are also a feature of holographic fluids. These results support the application of hydrodynamics in problems involving the interaction between fluids and gravitational waves.

   hep-phPRD(2021)·14 citations
3. 03*

   Muon $(g-2)$ and Flavor Puzzles in the $U(1{)}_X^{}$-gauged Leptoquark Model

   Xin Wang🇨🇳

   We present an economical model where an $S_1^{}$ leptoquark and an anomaly-free $U(1{)}_X^{}$ gauge symmetry with $X=B_3^{}-2L_{\mu }^{}/3-L_{\tau }^{}/3$ are introduced, to account for the muon anomalous magnetic moment $a_{\mu }^{}\equiv (g_{\mu }^{}-2)$ and flavor puzzles including $R_{K^{(\ast {)}_{}}}^{}$ and $R_{D^{(\ast {)}_{}}}^{}$ anomalies together with quark and lepton flavor mixing. The $Z_{}^{\prime }$ gauge boson associated with the $U(1{)}_X^{}$ symmetry is responsible for the $R_{K^{(\ast {)}_{}}}^{}$ anomaly. Meanwhile, the specific flavor mixing patterns of quarks and leptons can be generated after the spontaneous breakdown of the $U(1{)}_X^{}$ gauge symmetry via the Froggatt-Nielsen mechanism. The $S_1^{}$ leptoquark which is also charged under the $U(1{)}_X^{}$ gauge symmetry can simultaneously explain the latest muon $(g-2)$ result and the $R_{D^{(\ast {)}_{}}}^{}$ anomaly. In addition, we also discuss several other experimental constraints on our model.

   hep-phJHEP(2022)·18 citations
4. 04*

   A detailed study of charm content of a proton in the frameworks of the Kimber-Martin-Ryskin and Martin-Ryskin-Watt approaches

   N. Olanj🇮🇷 · M. Modarres🇮🇷

   The charm structure function, ($F_2^{c\overline{c}}(x,Q^2)$), is calculated in the framework of the $k_t$-factorization formalism by using the unintegrated parton distribution functions (UPDF), which are generated through the Kimber et al. (KMR) and Martin et al. (MRW) procedures. The Martin group (MMHT2014) parton distribution functions (PDF) is used as the input PDF for the corresponding UPDF. The resulted $F_2^{c\overline{c}}(x,Q^2)$ is compared with the predicted data and the calculations given by the ZEUS and H1 collaborations, the parton pQCD theory, i.e. the general-mass variable-flavour-number scheme (GMVFNS), the LO collinear procedure and the saturation model introduced by Golec-Biernat and Wüsthoff (GBW), respectively. In general, it is shown that the calculated charm structure functions based on the stated above two UPDF schemes are consistent with the experimental data and other theoretical predictions. Also, a short discussion is presented regarding the KMR and MRW UPDF behaviors.

   hep-phhep-exNPA(2020)·5 citations
5. 05*

   Extracting the parton distribution functions evolution equations using the stochastic modeling in the non-equilibrium statistical mechanics

   N. Olanj🇮🇷 · E. Moradi🇮🇷 · M. Modarres🇮🇷

   In this paper, using the stochastic modeling of the non-equilibrium statistical mechanics in the momentum space, the evolution equations of the parton distribution functions (PDF) usually used in the hadrons phenomenology are generated. These stochastic modeling PDF evolution equations are the same as those of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) ones, but they can be obtained by a more simplistic mathematical procedure based on the non-equilibrium statistical mechanics and the theory of Markov processes.

   hep-phhep-exPhysica A(2020)·2 citations
6. 06*

   Semileptonic ${\Xi }_c$ baryon decays in the light cone QCD sum rules

   T.M.Aliev🇹🇷 · S.Bilmis🇹🇷 · M.Savci🇹🇷

   Form factors of the weak ${\Xi }_c\to \Xi (\Lambda )$ transitions are calculated within the light cone QCD sum rules. The pollutions coming from the contribution of the negative parity ${\Xi }_c^{\ast }$ baryon is eliminated by considering the combinations of sum rules corresponding to the different Lorentz structures. Having obtained the form factors, the branching ratios of the ${\Xi }_c\to \Xi (\Lambda )\ell \nu$ decays are also calculated, and our predictions are compared with the results of other approaches as well as the measurements done by BELLE and ALICE Collaborations.

   hep-phPRD(2021)·12 citations
7. 07*

   Transverse-momentum-dependent parton distribution functions for spin-1 hadrons

   S. Kumano🇯🇵 · Qin-Tao Song🇨🇳

   We show transverse-momentum-dependent parton distribution functions (TMDs) for spin-1 hadrons including twist-3 and 4 functions by taking the decomposition of a quark correlation function in the Lorentz-invariant way with the conditions of Hermiticity and parity invariance. We found 30 new TMDs in the tensor-polarized spin-1 hadron at twists 3 and 4 in addition to 10 TMDs at twist 2. Since time-reversal-odd terms of the collinear correlation function should vanish after integrals over the partonic transverse momentum, we obtained new sum rules for the time-reversal-odd structure functions, $\int {\mathbf{d}}^2{\mathbf{k}}_{\mathbf{T}}{\mathbf{g}}_{\mathbf{LT}}=\int {\mathbf{d}}^2{\mathbf{k}}_{\mathbf{T}}{\mathbf{h}}_{\mathbf{LL}}=\int {\mathbf{d}}^2{\mathbf{k}}_{\mathbf{T}}{\mathbf{h}}_{3\mathbf{LL}}$$=0$, at twists 3 and 4. We also indicated that transverse-momentum-dependent fragmentation functions exist in tensor-polarized spin-1 hadrons. The TMDs can probe color degrees of freedom, so that they are valuable in providing unique opportunities for creating interdisciplinary physics fields such as gluon condensate, color Aharonov-Bohm effect, and color entanglement. We also found three new collinear PDFs at twists 3 and 4, and a twist-2 relation and a sum rule were derived in analogy to the Wandzura-Wilczek relation and the Burkhardt-Cottingham sum rule on the structure function ${\mathbf{g}}_2$.

   hep-phhep-exhep-latnucl-thSciPost Phys.Proc.(2022)·0 citations
8. 08*

   Probing Virtual ALPs by Precision Phase Measurements: Time-Varying Magnetic Field Background

   Mohammad Sharifian🇮🇷 · Moslem Zarei🇮🇷 · Mehdi Abdi🇮🇷 · Marco Peloso🇮🇹 · Sabino Matarrese🇮🇹

   We propose an experimental scheme for detecting the effects of off-shell axion-like particles (ALPs) through optical cavities. In this proposed experiment, linearly polarized photons are pumped into an optical cavity where an external time-dependent magnetic field is present. The magnetic field mediates an interaction between the cavity photons and ALPs giving rise to a modification in the phase of the cavity photons. The time-dependent nature of the external magnetic field prompts a novel amplification effect which significantly enhances this phase modification. A detection scheme is then proposed to identify such axion-induced phase shifts. We find that the phase modification is considerably sensitive to the photon-ALPs coupling constants $g_{a\gamma \gamma }$ for the range of ALPs mass $3.1\mu \text{eV}⩽m_a⩽44.4\mu \text{eV}$.

   hep-phastro-ph.COJCAP(2023)·5 citations
9. 09*

   Parametric co-linear axion photon instability

   K. A. Beyer🇬🇧 · G. Marocco🇬🇧 · C. Danson🇬🇧 · R. Bingham🇬🇧 · G. Gregori🇬🇧

   Axions and axion-like particles generically couple to QED via the axion-photon-photon interaction. This leads to a modification of Maxwell's equations known in the literature as axion-electrodynamics. The new form of Maxwell's equations gives rise to a new parametric instability in which a strong pump decays into a scattered light wave and an axion. This axion mode grows exponentially in time and leads to a change in the polarisation of the initial laser beam, therefore providing a signal for detection. Currently operating laser systems can put bounds on the axion parameter space, however longer pulselengths are necessary to reach the current best laboratory bounds of light-shining through wall experiments.

   hep-phPLB(2023)·10 citations
10. 10*

    Charmed meson production based on dipole transverse momentum representation in high energy hadron-hadron collisions available at the LHC

    G. Sampaio dos Santos🇧🇷 · G. Gil da Silveira🇧🇷 · M. V. T. Machado🇧🇷

    The production of $D$-mesons in high-energy $pp$ collisions at the LHC kinematic regime is analyzed with the dipole approach in the momentum representation. We present predictions for the $D$-meson differential cross section in terms of the transverse momentum and rapidity distributions taking into account the nonlinear behavior of the QCD dynamics. Comparison between our results and the corresponding experimental measurements reported by the ALICE and LHCb Collaborations in different rapidity bins is performed. We show that the $D$-meson production in the high energy limit can be properly addressed by using the QCD dipole transverse momentum distributions.

    hep-phhep-exPLB(2023)·10 citations
11. 11*

    Nonlinear diffusion of gluons

    Georg Wolschin🇩🇪

    It is proposed to consider the fast thermalization of gluons in relativistic heavy-ion collisions as a diffusion process in momentum space. Closed-form analytical solutions of a nonlinear boson diffusion equation (NBDE) with constant drift and diffusion coefficients v, D and boundary conditions at the singularity are derived. The time evolution towards local central temperatures T< 600 MeV through inelastic gluon scatterings in heavy-ion collisions is calculated for under- and overoccupied systems in the full momentum range. The results are consistent with QCD-based numerical calculations for gluon thermalization via inelastic gluon collisions.

    hep-phnucl-thPhysica A: Statistical Mechanics and its Applications(2022)·2 citations
12. 12*

    Computation of Gravitational Particle Production Using Adiabatic Invariants

    Edward E. Basso🇺🇸 · Daniel J.H. Chung🇺🇸

    Analytic and numerical techniques are presented for computing gravitational production of scalar particles in the limit that the inflaton mass is much larger than the Hubble expansion rate at the end of inflation. These techniques rely upon adiabatic invariants and time modeling of a typical inflaton field which has slow and fast time variation components. A faster computation time for numerical integration is achieved via subtraction of slowly varying components that are ultimately exponentially suppressed. The fast oscillatory remnant results in production of scalar particles with a mass larger than the inflationary Hubble expansion rate through a mechanism analogous to perturbative particle scattering. An improved effective Boltzmann collision equation description of this particle production mechanism is developed. This model allows computation of the spectrum using only adiabatic invariants, avoiding the need to explicitly solve the inflaton equations of motion.

    hep-phgr-qchep-thphysics.comp-phJHEP(2021)·14 citations
13. 13*

    Extending Precision Perturbative QCD with Track Functions

    Yibei Li🇨🇳 · Ian Moult🇺🇸 · Solange Schrijnder van Velzen🇳🇱 · Wouter J. Waalewijn🇳🇱 · Hua Xing Zhu🇨🇳

    Collider experiments often exploit information about the quantum numbers of final state hadrons to maximize their sensitivity, with applications ranging from the use of tracking information (electric charge) for precision jet substructure measurements, to flavor tagging for nucleon structure studies. For such measurements, perturbative calculations in terms of quarks and gluons are insufficient, and non-perturbative track functions describing the energy fraction of a quark or gluon converted into a subset of hadrons (e.g., charged hadrons) must be incorporated. Unlike fragmentation functions, track functions describe correlations between hadrons and therefore satisfy complicated non-linear evolution equations whose structure has so far eluded calculation beyond the leading order. In this Letter, we develop an understanding of track functions and their interplay with energy flow observables beyond the leading order, allowing them to be used in state-of-the-art perturbative calculations for the first time. We identify a shift symmetry in the evolution of their moments that fixes their structure, and we explicitly compute the evolution of the first three moments at next-to-leading order, allowing for the description of up to three-point energy correlations. We then calculate the two-point energy correlator on charged particles at $O({\alpha }_s^2)$, illustrating explicitly that infrared singularities in perturbation theory are absorbed by moments of the track functions and also highlighting how these moments seamlessly interplay with modern techniques for perturbative calculations. Our results extend the boundaries of traditional perturbative QCD, enabling precision perturbative predictions for energy flow observables sensitive to the quantum numbers of hadronic states.

    hep-phhep-exnucl-exnucl-thPRL(2022)·93 citations
14. 14*

    Constraints on heavy decaying dark matter with current gamma-ray measurements

    Marco Chianese🇮🇹 · Damiano F. G. Fiorillo🇮🇹 · Rasmi Hajjar🇮🇹 · Gennaro Miele🇮🇹 · Ninetta Saviano🇮🇹

    Among the several strategies for indirect searches of dark matter, one very promising one is to look for the gamma-rays from decaying dark matter. Here we use the most up-to-date upper bounds on the gamma-ray flux from $10^5$ to $10^{11}$ GeV, obtained from CASA-MIA, KASCADE, KASCADE-Grande, Pierre Auger Observatory, and Telescope Array. We obtain global limits on dark matter lifetime in the range of masses $m_{\mathrm{DM}}=[10^7-10^{15}]\mathrm{GeV}$. We provide the bounds for a set of decay channels chosen as representatives. The constraints derived here are new and cover a region of the parameter space not yet explored. We compare our results with the projected constraints from future neutrino telescopes, in order to quantify the improvement that will be obtained by the complementary high-energy neutrino searches.

    hep-phastro-ph.COJCAP(2021)·46 citations
15. 15*

    Democratic Lagrangians for Nonlinear Electrodynamics

    Zhirayr Avetisyan🇺🇸 · Oleg Evnin🇹🇭 · Karapet Mkrtchyan🇬🇧

    We construct a Lagrangian for general nonlinear electrodynamics that features electric and magnetic potentials on equal footing. In the language of this Lagrangian, discrete and continuous electric-magnetic duality symmetries can be straightforwardly imposed, leading to a simple formulation for theories with the $SO(2)$ duality invariance. When specialized to the conformally invariant case, our construction provides a manifestly duality-symmetric formulation of the recently discovered ModMax theory. We briefly comment on a natural generalization of this approach to $p$-forms in $2p+2$ dimensions.

    ↳ hep-thhep-phmath-phmath.MP+2PRL(2021)·71 citations
16. 16*

    Scalar and Tensor Perturbations in DHOST Bounce Cosmology

    Mian Zhu🇨🇳 · Amara Ilyas🇨🇳 · Yunlong Zheng🇨🇳 · Yi-Fu Cai🇨🇳 · Emmanuel N.Saridakis🇬🇷

    We investigate the bounce realization in the framework of DHOST cosmology, focusing on the relation with observables. We perform a detailed analysis of the scalar and tensor perturbations during the Ekpyrotic contraction phase, the bounce phase, and the fast-roll expansion phase, calculating the power spectra, the spectral indices, and the tensor to-scalar ratio. Furthermore, we study the initial conditions, incorporating perturbations generated by Ekpyrotic vacuum fluctuations, by matter vacuum fluctuations, and by thermal fluctuations. The scale invariance of the scalar power spectrum can be acquired by introducing a matter contraction phase before the Ekpyrotic phase or invoking a thermal gas as the source. The DHOST bounce scenario with cosmological perturbations generated by thermal fluctuations proves to be the most efficient one, and the corresponding predictions are in perfect agreement with observational bounds. Especially the tensor-to-scalar ratio is many orders of magnitude within the allowed region since it is suppressed by the Hubble parameter at the beginning of the bounce phase.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2021)·62 citations
17. 17*

    Primordial blackholes from Gauss-Bonnet-corrected single field inflation

    Shinsuke Kawai🇰🇷 · Jinsu Kim🇨🇭

    Primordial blackholes formed in the early Universe via gravitational collapse of over-dense regions may contribute a significant amount to the present dark matter relic density. Inflation provides a natural framework for the production mechanism of primordial blackholes. For example, single field inflation models with a fine-tuned scalar potential may exhibit a period of ultra-slow roll, during which the curvature perturbation may be enhanced to become seeds of the primordial blackholes formed as the corresponding scales reenter the horizon. In this work, we propose an alternative mechanism for the primordial blackhole formation. We consider a model in which a scalar field is coupled to the Gauss-Bonnet term and show that primordial blackholes may be seeded when a scalar potential term and the Gauss-Bonnet coupling term are nearly balanced. Large curvature perturbation in this model not only leads to the production of primordial blackholes but it also sources gravitational waves at the second order. We calculate the present density parameter of the gravitational waves and discuss the detectability of the signals by comparing them with sensitivity bounds of future gravitational wave experiments.

    ↳ astro-ph.COhep-phhep-thPRD(2021)·174 citations
18. 18*

    Fermion-charged-boson stars

    Ben Kain🇺🇸

    Fermion-boson stars are starlike systems composed of the ordinary nuclear matter of a neutron star and bosonic dark matter. The bosonic dark matter has typically been taken to be a complex scalar field. A natural extension is for the complex scalar field to be charged. We make the simplest extension and gauge the scalar field under U(1). We therefore study fermion-charged-boson stars. We make a detailed study of the stability of this system by computing critical curves over the whole of parameter space. We then study how the fermion and boson sectors contribute to the total mass of the star. Finally, we present mass-radius diagrams, showing that an increase in charge can lead to more massive and more compact stars.

    ↳ gr-qcastro-ph.HEhep-phPRD(2021)·18 citations
19. 19*

    The interior of hairy black holes in standard model physics

    Theo M. Nieuwenhuizen🇳🇱

    A large class of stationary, non-rotating black hole metrics is proposed, in which the interior is regular with a core consisting of a condensate of Higgs and $Z$ bosons generated from the nuclear binding energy of the initial H atoms. Gravitational collapse is prevented by negative pressures from the Higgs condensate and a small imbalance in the distribution of electric charges. Non-condensed, thermal particles are present as well. The approach holds for masses exceeding 0.75 $10^{-4}{M}_{\odot }$. The inner horizon sets an inner core of 11 cm, while the characteristic radius of the full core is 270 $(M/M_{\odot }{)}^{1/3}$ cm. For increasing charge, the core expands; in the extremal case, it fills the interior. While the net charge is easily shielded, the build up of horizons may prevent this in the interior, and consequently avoid a singularity. In black hole merging, the core of a nearly extremal one may be exposed, forming a new class of events. The approach is a stepping stone towards rotating black holes.

    ↳ gr-qcastro-ph.HEhep-ph2 citations
20. 20*

    Pion photoproduction in chiral perturbation theory with explicit treatment of the $\Delta (1232)$ resonance

    N. Rijneveen🇩🇪 · A. M. Gasparyan🇩🇪 · H. Krebs🇩🇪 · E. Epelbaum🇩🇪

    We study the reaction of pion photoproduction on the nucleon in the framework of chiral perturbation theory with explicit $\Delta (1232)$ degrees of freedom. In the covariant approach, we give results up to order ${ϵ}^3$ in the small scale expansion scheme. Furthermore, we provide $\Delta$-less and $\Delta$-full results obtained in the heavy-baryon scheme to analyze the differences to the covariant approach. Low energy constants are fitted to multipole amplitudes using theoretical truncation errors estimated by a Bayesian approach. We also compare our findings to data of neutral pion production cross sections and polarization asymmetries. The description of the reaction is clearly improved by the explicit treatment of the $\Delta (1232)$ resonance.

    ↳ nucl-thhep-phPRC(2022)·12 citations
21. 21*

    Antiproton-deuteron hydrogenic states in optical models

    Rimantas Lazauskas · Jaume Carbonell

    By solving the Faddeev equations for the p̄pn system, we compute the antiproton-deuteron level shifts and widths for the lowest hydrogenic states as well as the corresponding p̄d scattering lengths and volumes. The p̄d annihilation densities are obtained and compared to the nuclear density of deuterium. The validity of the Trueman relation for composite particles is studied. The strong part of N̄N interaction is described by two different optical models, including the p̄p-n̄n coupling and n-p mass difference, while for NN several realistic interactions are used.

    ↳ nucl-thhep-phPLB(2021)·14 citations
22. 22*

    A First Detection of the Connected 4-Point Correlation Function of Galaxies Using the BOSS CMASS Sample

    Oliver H. E. Philcox🇺🇸 · Jiamin Hou🇺🇸 · Zachary Slepian🇺🇸

    We present an $8.1\sigma$ detection of the non-Gaussian 4-Point Correlation Function (4PCF) using a sample of $N_{\mathrm{g}}\approx 8\times 10^5$ galaxies from the BOSS CMASS dataset. Our measurement uses the $\mathcal{O}(N_{\mathrm{g}}^2)$ NPCF estimator of Philcox et al. (2021), including a new modification to subtract the disconnected 4PCF contribution (arising from the product of two 2PCFs) at the estimator level. This approach is unlike previous work and ensures that our signal is a robust detection of gravitationally-induced non-Gaussianity. The estimator is validated with a suite of lognormal simulations, and the analytic form of the disconnected contribution is discussed. Due to the high dimensionality of the 4PCF, data compression is required; we use a signal-to-noise-based scheme calibrated from theoretical covariance matrices to restrict to $\sim$ $100$ basis vectors. The compression has minimal impact on the detection significance and facilitates traditional ${\chi }^2$-like analyses using a suite of mock catalogs. The significance is stable with respect to different treatments of noise in the sample covariance (arising from the limited number of mocks), but decreases to $4.7\sigma$ when a minimum galaxy separation of $14h^{-1}\mathrm{Mpc}$ is enforced on the 4PCF tetrahedra (such that the statistic can be modelled more easily). The detectability of the 4PCF in the quasi-linear regime implies that it will become a useful tool in constraining cosmological and galaxy formation parameters from upcoming spectroscopic surveys.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ex+166 citations
23. 23*

    Horndeski stars

    Juan Barranco🇲🇽 · Javier Chagoya🇲🇽 · Alberto Diez-Tejedor🇲🇽 · Gustavo Niz🇲🇽 · Armando A. Roque🇲🇽

    We establish the existence of time-dependent solitons in a modified gravity framework, which is defined by the low energy limit of theories with a weakly broken galileon symmetry and a mass term. These are regular vacuum configurations of finite energy characterized by a single continuous parameter representing the amplitude of the scalar degree of freedom at the origin. When the central field amplitude is small the objects are indistinguishable from boson stars. In contrast, increasing the central value of the amplitude triggers the effect of higher derivative operators in the effective theory, leading to departures from the previous solutions, until the theory becomes strongly coupled and model-dependent. The higher order operators are part of the (beyond) Horndeski theory, hence the name of the compact objects. Moreover, a remnant of the galileon non-renormalization theorem guarantees that the existence and properties of these solutions are not affected by quantum corrections. Finally, we discuss the linear stability under small radial perturbations, the mass-radius relation, the compactness, the appearance of innermost stable circular orbits and photon spheres, and some astrophysical signatures (accretion disks, gravitational radiation and lensing) that may be relevant to falsify the model.

    ↳ gr-qcastro-ph.COhep-phJCAP(2021)·19 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.