Tue·Apr 27, 2021Tuesday·April 27, 2021

1. 01*

   Helicity Evolution at Small $x$: the Single-Logarithmic Contribution

   Yuri V. Kovchegov🇺🇸 · Andrey Tarasov🇺🇸 · Yossathorn Tawabutr🇺🇸

   We calculate single-logarithmic corrections to the small-$x$ flavor-singlet helicity evolution equations derived recently in the double-logarithmic approximation. The new single-logarithmic part of the evolution kernel sums up powers of ${\alpha }_s\ln (1/x)$, which are an important correction to the dominant powers of ${\alpha }_s{\ln }^2(1/x)$ summed up by the double-logarithmic kernel at small values of Bjorken $x$ and with ${\alpha }_s$ the strong coupling constant. The single-logarithmic terms arise separately from either the longitudinal or transverse momentum integrals. Consequently, the evolution equations we derive employing the light-cone perturbation theory simultaneously include the small-$x$ evolution kernel and the leading-order polarized DGLAP splitting functions. We further enhance the equations by calculating the running coupling corrections to the kernel.

   hep-phhep-exnucl-exnucl-thJHEP(2022)·53 citations
2. 02*

   Higher-Order Corrections to the Bubble-Nucleation Rate at Finite Temperature

   Andreas Ekstedt🇸🇪

   In this paper I discuss how to consistently incorporate higher-order corrections to the bubble-nucleation rate at finite temperature. Doing so I examine the merits of different approaches, with the goal of reducing uncertainties for gravitational-wave calculations. To be specific, the region of applicability and accuracy of the derivative expansion is discussed. The derivative expansion is then compared to a numerical implementation of the Gelfand-Yaglom theorem. Both methods are applied to popular first-order phase transition models, like a loop-induced barrier and a SM-EFT tree-level barrier. The results of these calculations are presented in easy-to-use parametrizations that can directly be used in gravitational-wave calculations. In addition, higher-order corrections for models with multiple scalar fields, such as singlet/triplet extensions, are studied. Lastly, the convergence and uncertainty of all calculations are discussed in detail. And I argue that leading-order results for the Standard Model with a tree-level barrier might be inaccurate.

   hep-phEPJC(2022)·51 citations
3. 03*

   Nonrelativistic Treatment of Fully-Heavy Tetraquarks as Diquark-Antidiquark States

   Halil Mutuk🇹🇷

   The goal of the present work is to obtain a reliable estimate of the masses of the ground and radially excited states of fully-heavy tetraquark systems. In order to do this, we use a nonrelativistic model of tetraquarks which are assumed to be compact and consist of diquark-antidiquark pairs. This nonrelativistic model is composed of Hulthen potential, a linear confining potential and spin-spin interaction. We computed ground, first, and second radially excited $cc\bar{c}\bar{c}$ and $bb\bar{b}\bar{b}$ tetraquark masses. It was found that predicted masses of ground states of $cc\bar{c}\bar{c}$ and $bb\bar{b}\bar{b}$ tetraquarks are significantly higher than the thresholds of the fall-apart decays to the lowest allowed two-meson states. These states should be broad and are thus difficult to observe experimentally. First radially excited states are considerably lower than their corresponding (2S-2S) two-meson thresholds. We hope that our study may be helpful to the experimental search for ground and excited $cc\bar{c}\bar{c}$ and $bb\bar{b}\bar{b}$ tetraquark states.

   hep-phhep-exEPJC(2021)·74 citations
4. 04*

   The Thermal Feedback Effects on the Temperature Evolution during Reheating

   Lei Ming🇨🇳

   The time dependence of the temperature during the reheating process is studied. We consider the thermal feedback effects of the produced particles on the effective dissipation rate of the inflaton field, which can lead to enhanced production of particles. We parameterize the temperature dependence of the dissipation rate in terms of a Taylor expansion containing the vacuum decay rate and the thermal terms. By solving the Boltzmann equations for the energy densities of the inflaton and radiation, we provide analytic estimates for a general power law dependence on the temperature. In this way we describe the entire reheating process. The maximum temperature of the reheating process and its dependence on model parameters are studied in different cases. The impact of the thermal feedback effects on the expansion history of the universe and the cosmic microwave background (CMB) is discussed. We also discuss the range of validity of our approach.

   hep-phgr-qcInt.J.Mod.Phys.A(2021)·7 citations
5. 05*

   Diagonal reflection symmetries, four-zero texture, and trimaximal mixing with predicted ${\theta }_{13}$ in an $A_4$ symmeric model

   Masaki J. S. Yang🇯🇵

   In this paper, we impose a magic symmetry on the neutrino mass matrix $m_{\nu }$ with universal four-zero texture and diagonal reflection symmetries. Due to the magic symmetry, the MNS matrix has trimaximal mixing inevitably. Since the lepton sector has only six free parameters, physical observables of leptons are all determined from the charged leptons masses $m_{ei}$, the neutrino mass differences $\Delta m_{i1}^2$, and the mixing angle ${\theta }_{23}$. This scheme predicts $\sin {\theta }_{13}=0.149$, that is almost equal to the latest best fit, as a function of the lepton masses $m_{e,\mu }$ and the mass differences $\Delta m_{i1}^2$. Moreover, even if the mass matrix has perturbations that break the magic symmetry, the prediction of $\sin {\theta }_{13}$ is retained with good accuracy for the four-zero texture with diagonal reflection symmetries.

   hep-phPTEP·39 citations
6. 06*

   Study of Dependence of Kinetic Freezeout Temperature on the Production Cross Section of Particles in Various Centrality Intervals in Au Au and Pb Pb Collisions at High Energies

   M. Waqas🇨🇳 · G. X. Peng🇨🇳

   Transverse momentum spectra of pion, proton, lambda, cascade, Omega and deuteron (d) in different centrality intervals in nucleus nucleus collisions at the center of mass energy are analyzed by the blast wave model with Boltzmann Gibbs statistics. We extracted the kinetic freezeout temperature, transverse flow velocity and kinetic freezeout volume from the transverse momentum spectra of the particles. It is observed that the non-strange and strange (multi strange) particles freezeout separately due to different reaction cross-sections. While the freezeout volume and transverse flow velocity are mass dependent, they decrease with the resting mass of the particles. The present work reveals the scenario of a double kinetic freezeout in nucleus nucleus collisions. Furthermore, the kinetic freezeout temperature and freezeout volume are larger in central collisions than peripheral collisions. However, the transverse flow velocity remains almost unchanged from central to peripheral collisions.

   hep-phEntropy(2021)·15 citations
7. 07*

   Analysis of the fully-heavy pentaquark states via the QCD sum rules

   Zhi-Gang Wang🇨🇳

   In the article, we investigate the diquark-diquark-antiquark type fully-heavy pentaquark states with the spin-parity $J^P={\frac{1}{2}}^{-}$ via the QCD sum rules, and obtain the masses $M_{cccc\bar{c}}=7.93\pm 0.15\mathrm{GeV}$ and $M_{bbbb\bar{b}}=23.91\pm 0.15\mathrm{GeV}$. We can search for the fully-heavy pentaquark states in the $J/\psi {\Omega }_{ccc}$ and ${\rm Y}{\Omega }_{bbb}$ invariant mass spectrum in the future.

   hep-phNPB(2021)·31 citations
8. 08*

   Thrust Distribution for 3-Jet Production from $e^{+}{e}^{-}$ Annihilation within the QCD Conformal Window and in QED

   Leonardo Di Giustino🇮🇹 · Francesco Sannino🇩🇰 · Sheng-Quan Wang🇨🇳 · Xing-Gang Wu🇨🇳

   We investigate the theoretical predictions for thrust distribution in the electron positron annihilation to three-jets process at NNLO for different values of the number of flavors, $N_f$. To determine the distribution along the entire renormalization group flow from the highest energies to zero energy we consider the number of flavors near the upper boundary of the conformal window. In this regime of number of flavors the theory develops a perturbative infrared interacting fixed point. We then consider also the QED thrust obtained as the limit $N_c\to 0$ of the number of colors. In this case the low energy limit is governed by an infrared free theory. Using these quantum field theories limits as theoretical laboratories we arrive at an interesting comparison between the Conventional Scale Setting - (CSS) and the Principle of Maximum Conformality (PMC${}_{\infty }$) methods. We show that within the perturbative regime of the conformal window and also out of the conformal window the PMC${}_{\infty }$ leads to a higher precision, and that reducing the number of flavors, from the upper boundary to the lower boundary, through the phase transition the curves given by the PMC${}_{\infty }$ method preserve with continuity the position of the peak, showing perfect agreement with the experimental data already at NNLO.

   hep-phhep-thPLB(2021)·12 citations
9. 09*

   $\sin ({\varphi }_{\Lambda }-{\varphi }_S)$ azimuthal asymmetry in transversely polarized $\Lambda$ production in SIDIS within TMD factorization at EIC

   Hui Li🇨🇳 · Xiaoyu Wang🇨🇳 · Zhun Lu🇨🇳

   We investigate the $\sin ({\varphi }_{\Lambda }-{\varphi }_S)$ single-spin asymmetry in the transversely polarized $\Lambda$ production in semi-inclusive deeply inelastic scattering process within the framework of the transverse momentum dependent~(TMD) factorization. The asymmetry is contributed by the convolution of the polarizing TMD fragmentation function $D_{1T}^{\perp }$ of the $\Lambda$ hyperon and the unpolarized TMD distribution function $f_1$ of the target nucleon. We apply two sets of $D_{1T}^{\perp ,{\Lambda }^{\uparrow }/q}$, the spectator diquark model result and available parametrization, to numerically estimate the $\sin ({\varphi }_{\Lambda }-{\varphi }_S)$ asymmetry at the kinematical region of electron ion collider (EIC). We take into account the TMD evolution effect in order to include the scale dependence of the TMD distribution functions and fragmentation functions. It is found that different sets of $D_{1T}^{\perp ,{\Lambda }^{\uparrow }/q}$ lead to different $\sin ({\varphi }_{\Lambda }-{\varphi }_S)$ asymmetry, particularly in sign. Future measurements on the $\sin ({\varphi }_{\Lambda }-{\varphi }_S)$ asymmetry with high precision at EIC can provide important cross check on the available $\Lambda$ polarizing fragmentation functions as well as constrain them more stringently.

   hep-phPRD(2021)·7 citations
10. 10*

    Novel imprint of a vector doublet

    Phung Van Dong🇻🇳 · Duong Van Loi🇻🇳 · Le Duc Thien🇻🇳 · Pham Ngoc Thu🇻🇳

    It is shown that the presence of a vector doublet is suitable to address neutrino mass, dark matter, and the recent muon anomalous magnetic moment.

    hep-phPRD(2021)·13 citations
11. 11*

    The low energy inclusive ${\nu }_{\mu }({\nu }_e){-}^{12}$C scattering revisited

    M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳

    We have reviewed the current status of the inclusive neutrino scattering from ${}^{12}$C in the low energy region corresponding to the neutrino beams from the pion, muon and kaon decaying at rest. The theoretical calculations of total cross sections in various nuclear models with special emphasis on the recent experiments with the monoenergetic neutrinos from KDAR [1] along with the older experiments from KARMEN and LSND collaborations have been discussed in the context of the recent works by Akbar et al. [2] and Nikolakopoulos et al. [3]. The inadequacy of the various theoretical models used to explain the experimental results on the inclusive neutrino scattering from nuclei at low energies has been highlighted and the need for a better understanding of the nuclear medium effects beyond the impulse approximation has been emphasized.

    hep-phnucl-th0 citations
12. 12*

    Calculated event rates for Axion Detection via Atomic and Nuclear Processes

    John D. Vergados🇬🇷 · Paraskevi C. Divari🇬🇷 · Hiroyasu Ejiri🇯🇵

    The possibility of detection of 5.5 MeV and 14.4 keV solar axions by observing axion-induced nuclear and atomic transitions is investigated. The presence of nuclear transitions between spin-orbit partners can be manifested by the subsequent de-excitation via gamma ray emissions. The transition rates can also be studied in the context of radiative axion absorption by a nucleus. The elementary interaction is obtained in the context of the axion-quark couplings predicted by existing axion models. Then these couplings will be transformed to the nucleon level utilizing reasonable existing models, which lead to effective transition operators. Using these operators we calculate the needed nuclear matrix elements employing wave functions obtained in the context of the nuclear shell model. With these ingredients, we discuss possibilities of experimental observation of the axion-induced nuclear gamma-rays. In the second part, we will examine the axion-induced production of X-rays (axion-photon conversion) or ionization from deeply bound electron orbits. In this case, the axion electron coupling is predicted by existing axion models, no renormalization is needed. The experimental signal is the observation of directly produced electrons and/or the emission of hard X-rays and Auger electrons, following the de-excitation of the final atom. Critical discussion is made on the experimental feasibility of detecting the solar axions by using multi-ton scale NaI detectors.

    hep-phAdv.High Energy Phys.(2022)·10 citations
13. 13*

    Predicting outcomes of electric dipole and magnetic moment experiments

    V. G. Baryshevsky🇧🇾 · P. I. Porshnev🇧🇾

    The anomalous magnetic and electric dipole moments in spin motion equation acquire pseudoscalar corrections if the $T(CP)$-noninvariance is admitted. It allows to explain the discrepancy between experimental and theoretical values of muon $(g-2)$ factor under assumption that the pseudoscalar correction is the dominant source of this discrepancy.

    hep-phPhys.Scripta(2022)·3 citations
14. 14*

    Rare Lepton-Number-Violating $W$ Decays at the LHC: CP Violation

    David London🇨🇦

    Some models of leptogenesis involve a nearly-degenerate pair of heavy Majorana neutrinos $N_{1,2}$ whose masses can be small, $O(\mathrm{GeV})$. There can be heavy-light neutrino mixing parametrized by $|B_{\ell N}{|}^2=10^{-5}$, which leads to the rare lepton-number-violating decay $W^{\pm }\to {\ell }_1^{\pm }{\ell }_2^{\pm }(q^{\prime }\bar{q}{)}^{\mp }$. With contributions to this decay from both $N_1$ and $N_2$, a CP-violating rate difference between the decay and its CP-conjugate can be generated. In this talk, I describe the prospects for measuring such a CP asymmetry $A_{\mathrm{CP}}$ at the LHC. I consider three versions of the LHC -- HL-LHC, HE-LHC, FCC-hh -- and show that, for $5\mathrm{GeV}\le M_N\le 80\mathrm{GeV}$, small values of the CP asymmetry can be measured at $3\sigma$, in the range $1\%\le A_{\mathrm{CP}}\le 15\%$.

    hep-ph0 citations
15. 15*

    Limits on Magnetized Quark-Nugget Dark Matter from Episodic Natural Events

    J. Pace VanDevender🇺🇸 · Aaron P. VanDevender🇺🇸 · Peter Wilson🇮🇪 · Benjamin F. Hammel🇺🇸 · Niall McGinley🇮🇪

    A quark nugget is a hypothetical dark-matter candidate composed of approximately equal numbers of up, down, and strange quarks. Most models of quark nuggets do not include effects of their intrinsic magnetic field. However, Tatsumi used a mathematically tractable approximation of the Standard Model of Particle Physics and found that the cores of magnetar pulsars may be quark nuggets in a ferromagnetic liquid state with surface magnetic field Bo between $10^{11}$ T and $10^{13}$ T. We have applied that result to quark-nugget dark matter. Previous work addressed the formation and aggregation of magnetized quark nuggets (MQNs) into a broad and magnetically stabilized mass distribution before they could decay and addressed their interaction with normal matter through their magnetopause, losing translational velocity while gaining rotational velocity and radiating electromagnetic energy. The two orders of magnitude uncertainty in Tatsumi estimate for Bo precludes the practical design of systematic experiments to detect MQNs through their predicted interaction with matter. In this paper, we examine episodic events consistent with a unique signature of MQNs. If they are indeed caused by MQNs, they constrain the most likely values of Bo to $1.65x10^{12}$ T $+/-$ $21\%$ and support the design of definitive tests of the MQN dark-matter hypothesis.

    hep-phastro-ph.COgr-qcUniverse(2021)·5 citations
16. 16*

    Pion couplings with low-lying nucleon resonances

    Janardan Prasad Singh🇮🇳

    We have calculated coupling constants of a neutral pion with the lowest two nucleon resonances. This includes both the diagonal as well as non-diagonal coupling constants involving a nucleon resonance and a nucleon. For this, we first calculate vacuum-to-pion correlation function of the interpolating fields of two nucleons and then take its matrix elements with respect to a nucleon spinor and/or a nucleon resonance spinor(s). Using different QCD sum rules obtained from different matrix elements we eliminate unwanted coupling constants and solve for the desired ones. This is a simple extension of the projected correlation function approach used in the literature where we use multiple of states involving those of a nucleon and its resonances. We have also checked the stability of our results with respect to variation of different QCD and phenomenological input parameters.

    hep-phnucl-thNPA(2022)·1 citation
17. 17*

    Mass spectra and wave functions of $T_{QQ\bar{Q}\bar{Q}}$ tetraquarks

    Qiang Li🇨🇳 · Chao-Hsi Chang🇨🇳 · Guo-Li Wang🇨🇳 · Tianhong Wang🇨🇳

    The compact tetraquark states with fully heavy quark contents $QQ\bar{Q}\bar{Q}$ are studied as the bound states of the diquark-antidiquark within the Bethe-Salpeter framework. The (anti)diquark masses and form factors used are the same as we calculated the doubly heavy baryons in a previous work. Under the instantaneous approximation, the three-dimensional (Bethe-)Salpeter equation of the tetraquarks is derived and solved numerically to obtain the corresponding mass spectra and wave functions of the tetraquarks with $J^{PC}=0^{++}$, $1^{+-}$, and $2^{++}$. Our results show that the three ground states of $cc\bar{c}\bar{c}$ locate in the mass range of $6.4\sim 6.5$GeV, and the $bb\bar{b}\bar{b}$ states in mass range of $19.2\sim 19.3$GeV. The obtained relativistic wave functions naturally include the mixing effects from the possible $D$\,(or $G$) partial waves, and then can be further used to do precise calculations of the tetraquark decays. Based on the obtained results, the LHCb's observation $X(6900)$ is less likely to be the ground states of compact $cc\bar{c}\bar{c}$ tetraquarks but might be the first or second excited states. In addition, a widely used propagator-like form factor is also investigated and discussed.

    hep-phPRD(2021)·58 citations
18. 18*

    The Principle of Global Relativity

    J. J. van der Bij🇩🇪

    We describe the non-minimal Standard Model, consisting of minimalistic extensions of the Standard Model, which for all we know is the theory of the universe, able to describe all of the universe from the beginning of time. Extensions discussed are an extra neutrino and a new Higgs model. We introduce the principle of global relativity and discuss how the theory can be largely derived from this principle. One is led to the unification of forces into SU(5) and a form of dark matter. We discuss the limitations of the theory, showing that it is not the theory of everything. However we argue that it is the only part, that is within conceivable reach of physical experiment or astronomical observations. It is argued, that at the Planck scale the universe is effectively three-dimensional.

    hep-phgr-qchep-thActa Phys.Polon.B(2021)·0 citations
19. 19*

    Pancharatnam-Berry phase in neutrino mixing

    Manosh T.M.🇮🇳 · N. Shaji🇮🇳 · Ramesh Babu Thayyullathil🇮🇳 · Titus K. Mathew🇮🇳

    The Pancharatnam - Berry phase (PBP) of purely geometric origin appears as a reparametrization invariant quantity of ray Space. In this article, we investigate the properties exhibited by PBP in neutrino mixing. We map the neutrino flavour modes to independent flavour vacuum states and compute PBP using Bargmann invariant. We derive the exact formula for PBP in two flavour approximation using the kinematic approach. Our result reproduces previous results of Blasone et al. under cyclic condition. Inspired by the work of Mukunda and Simon, we investigate the total and dynamical phases separately. This method leads us to identify the existence of nodal points in the mixing parameter space. At nodal points, PBP changes by a value $\pi$, and it originates from the total phase. We report the direct relation between nodal points and MSW resonance, giving physical meaning to nodal points. Our analysis shows the ability of PBP to differentiate between different mass hierarchies and set numerical bounds to $\Delta m^2$ by changing total energy. We extend our studies to three flavour model and found that PBP is sensitive to the Dirac $CP$ phase (${\delta }_{CP}$). Using our $N$-qubit architecture of the $N$-flavour neutrino model, one can immediately study the dynamical characteristics like mode entanglement between neutrino flavour modes.

    hep-phquant-ph1 citation
20. 20*

    An explicit calculation of pseudo-goldstino mass at the leading three-loop level

    Jianpeng Dai🇨🇳 · Tao Liu🇨🇳 · Jin Min Yang🇨🇳

    Pseudo-goldstinos appear in the scenario of multi-sector SUSY breaking. Unlike the true goldstino which is massless and absorbed by the gravitino, pseudo-goldstinos could obtain mass from radiative effects. In this note, working in the scenario of two-sector SUSY breaking with gauge mediation, we explicitly calculate the pseudo-goldstino mass at the leading three-loop level and provide the analytical results. In our calculation we consider the general case of messenger masses (not necessarily equal) and include the higher order terms of SUSY breaking scales. Our results can reproduce the numerical value estimated previously at the leading order of SUSY breaking scales with the assumption of equal messenger masses. It turns out that the results are very sensitive to the ratio of messenger masses, while the higher order terms of SUSY breaking scales are rather small in magnitude. Depending on the ratio of messenger masses, the pseudo-goldstino mass can be as low as $\mathcal{O}(0.1)$ GeV.

    hep-phhep-thJHEP(2021)·7 citations
21. 21*

    Probing the electroweak symmetry breaking with Higgs production at the LHC

    Ke-Pan Xie🇰🇷 · Bin Yan🇺🇸

    The electroweak symmetry breaking (EWSB) mechanism is still an undecided question in particle physics. We propose to utilize the single top quark and Higgs associated production ($th$), $Zh$ production via gluon fusion at the LHC to probe the couplings between the Higgs and the gauge bosons and further to test the EWSB. We demonstrate that the $th$ and $gg\to Zh$ productions are sensitive to the relative sign of couplings ($ht\bar{t}$, $hWW$) and ($ht\bar{t}$, $hZZ$), respectively. We find that the relative sign between $hWW$ and $hZZ$ couplings could be fully determined after combining the present measurements from $gg\to h$, $t\bar{t}h$ and the $th$, $Zh$ channels, as well as $tZj$ and $Zt\bar{t}$ production at the 13 TeV LHC, and this conclusion is not sensitive to the possible new physics contribution induced by $Zt\bar{t}$ couplings in the $gg\to Zh$ production.

    hep-phhep-exPLB(2021)·17 citations
22. 22*

    Invariant polynomials and machine learning

    Ward Haddadin🇬🇧

    We present an application of invariant polynomials in machine learning. Using the methods developed in previous work, we obtain two types of generators of the Lorentz- and permutation-invariant polynomials in particle momenta; minimal algebra generators and Hironaka decompositions. We discuss and prove some approximation theorems to make use of these invariant generators in machine learning algorithms in general and in neural networks specifically. By implementing these generators in neural networks applied to regression tasks, we test the improvements in performance under a wide range of hyperparameter choices and find a reduction of the loss on training data and a significant reduction of the loss on validation data. For a different approach on quantifying the performance of these neural networks, we treat the problem from a Bayesian inference perspective and employ nested sampling techniques to perform model comparison. Beyond a certain network size, we find that networks utilising Hironaka decompositions perform the best.

    hep-phcs.LGstat.ML3 citations
23. 23*

    The multiple-charm hierarchy in the statistical hadronization model

    Anton Andronic🇩🇪 · Peter Braun-Munzinger🇩🇪 · Markus K. Köhler🇩🇪 · Aleksas Mazeliauskas🇨🇭 · Krzysztof Redlich🇵🇱 · Johanna Stachel🇩🇪 · Vytautas Vislavicius🇩🇰

    In relativistic nuclear collisions the production of hadrons with light (u,d,s) quarks is quantitatively described in the framework of the Statistical Hadronization Model (SHM). Charm quarks are dominantly produced in initial hard collisions but interact strongly in the hot fireball and thermalize. Therefore charmed hadrons can be incorporated into the SHM by treating charm quarks as 'impurities' with thermal distributions, while the total charm content of the fireball is fixed by the measured open charm cross section. We call this model SHMc and demonstrate that with SHMc the measured multiplicities of single charm hadrons in lead-lead collisions at LHC energies can be well described with the same thermal parameters as for (u,d,s) hadrons. Furthermore, transverse momentum distributions are computed in a blast-wave model, which includes the resonance decay kinematics. SHMc is extended to lighter collision systems down to oxygen-oxygen and includes doubly- and triply-charmed hadrons. We show predictions for production probabilities of such states exhibiting a characteristic and quite spectacular enhancement hierarchy.

    hep-phnucl-exnucl-thJHEP(2021)·132 citations
24. 24*

    Evaporation of dark matter from celestial bodies

    Raghuveer Garani (INFN, Florence)🇮🇹 · Sergio Palomares-Ruiz (IFIC, Valencia U. - CSIC)🇪🇸

    Scatterings of galactic dark matter (DM) particles with the constituents of celestial bodies could result in their accumulation within these objects. Nevertheless, the finite temperature of the medium sets a minimum mass, the evaporation mass, that DM particles must have in order to remain trapped. DM particles below this mass are very likely to scatter to speeds higher than the escape velocity, so they would be kicked out of the capturing object and escape. Here, we compute the DM evaporation mass for all spherical celestial bodies in hydrostatic equilibrium, spanning the mass range $[10^{-10}-10^2]M_{\odot }$, for constant scattering cross sections and $s$-wave annihilations. We illustrate the critical importance of the exponential tail of the evaporation rate, which has not always been appreciated in recent literature, and obtain a robust result: for the geometric value of the scattering cross section and for interactions with nucleons, at the local galactic position, the DM evaporation mass for all spherical celestial bodies in hydrostatic equilibrium is approximately given by $E_c/T_{\chi }\sim 30$, where $E_c$ is the escape energy of DM particles at the core of the object and $T_{\chi }$ is their temperature. In that case, the minimum value of the DM evaporation mass is obtained for super-Jupiters and brown dwarfs, $m_{\mathrm{evap}}\simeq 0.7$ GeV. For other values of the scattering cross section, the DM evaporation mass only varies by a factor smaller than three within the range $10^{-41}{\text{cm}}^2\le {\sigma }_p\le 10^{-31}{\text{cm}}^2$, where ${\sigma }_p$ is the spin-independent DM-nucleon scattering cross section. Its dependence on parameters such as the galactic DM density and velocity, or the scattering and annihilation cross sections is only logarithmic, and details on the density and temperature profiles of celestial bodies have also a small impact.

    hep-phastro-ph.COastro-ph.EPastro-ph.HEJCAP(2022)·78 citations
25. 25*

    No evidence for axions from Chandra observation of magnetic white dwarf

    Christopher Dessert🇺🇸 · Andrew J. Long🇺🇸 · Benjamin R. Safdi🇺🇸

    Ultralight axions with axion-photon couplings $g_{a\gamma \gamma }\sim \mathrm{few}\times 10^{-11}$ GeV${}^{-1}$ may resolve a number of astrophysical anomalies, such as unexpected ~TeV transparency, anomalous stellar cooling, and X-ray excesses from nearby neutron stars. We show, however, that such axions are severely constrained by the non-observation of X-rays from the magnetic white dwarf (MWD) RE J0317-853 using ~40 ks of data acquired from a dedicated observation with the Chandra X-ray Observatory. Axions may be produced in the core of the MWD through electron bremsstrahlung and then convert to X-rays in the magnetosphere. The non-observation of X-rays constrains the axion-photon coupling to $g_{a\gamma \gamma }\lesssim 5.5\times 10^{-13}\sqrt{C_{a\gamma \gamma }/C_{aee}}$ GeV${}^{-1}$ at 95% confidence for axion masses $m_a\lesssim 5\times 10^{-6}$ eV, with $C_{aee}$ and $C_{a\gamma \gamma }$ the dimensionless coupling constants to electrons and photons. Considering that $C_{aee}$ is generated from the renormalization group, our results robustly disfavor $g_{a\gamma \gamma }\gtrsim 4.4\times 10^{-11}$ GeV${}^{-1}$ even for models with no ultraviolet contribution to $C_{aee}$.

    hep-phastro-ph.HEastro-ph.SRPRL(2022)·92 citations
26. 26*

    Higgs boson decay into photons at four loops

    Joshua Davies🇬🇧 · Florian Herren🇺🇸

    Future precision measurements of Higgs boson decays will determine the branching fraction for the decay into two photons with a precision at the one percent level. To fully exploit such measurements, equally precise theoretical predictions need to be available. To this end we compute four-loop QCD corrections in the large top quark mass expansion to the Higgs boson--photon form factor, which enter the two-photon decay width at next-to-next-to-next-to-leading order. Furthermore we obtain corrections to the two-photon decay width stemming from the emission of additional gluons, which contribute for the first time at next-to-next-to-leading order. Finally, we combine our results with other available perturbative corrections and estimate the residual uncertainty due to missing higher-order contributions.

    hep-phPRD(2021)·17 citations
27. 27*

    Hearing Higgs with Gravitational Wave Detectors

    Alberto Salvio🇮🇹

    The relic gravitational wave background due to tensor linear perturbations generated during Higgs inflation is computed. Both the Standard Model and a well-motivated phenomenological completion (that accounts for all the experimentally confirmed evidence of new physics) are considered. We focus on critical Higgs inflation, which improves on the non-critical version and features an amplification of the tensor fluctuations. The latter property allows us to establish that future space-borne interferometers, such as DECIGO, BBO and ALIA, may detect the corresponding primordial gravitational waves.

    hep-phastro-ph.COhep-thJCAP(2021)·6 citations
28. 28*

    Relic neutrinos at accelerator experiments

    Martin Bauer🇬🇧 · Jack D. Shergold🇬🇧

    We present a new technique for observing low energy neutrinos with the aim of detecting the cosmic neutrino background using ion storage rings. Utilising high energy targets exploits the quadratic increase in the neutrino capture cross section with beam energy, and with sufficient beam energy, enables neutrino capture through inverse-beta decay processes from a stable initial state. We also show that there exist ion systems admitting resonant neutrino capture, capable of achieving larger capture cross sections at lower beam energies than their non-resonant counterparts. We calculate the neutrino capture rate and the optimal experimental runtime for a range of different resonant processes and target ions and we demonstrate that the resonant capture experiment can be performed with beam energies as low as $\mathcal{O}(10\mathrm{TeV})$ per target nucleon. Unfortunately, none of the ion systems discussed here can provide sufficient statistics to discover the cosmic neutrino background with current technology. We address the challenges associated with realising this experiment in the future, taking into account the uncertainty in the beam and neutrino momentum distributions, synchrotron radiation, as well as the beam stability.

    hep-phhep-exPRD(2021)·29 citations
29. 29*

    Appendiciario -- A hands-on manual on the theory of direct Dark Matter detection

    Eugenio Del Nobile🇬🇧

    A manual for computations in direct Dark Matter detection phenomenology. Featuring self-contained sections on non-relativistic expansion, elastic and inelastic scattering kinematics, Dark Matter velocity distribution, hadronic matrix elements, nuclear form factors, cross sections, rate spectra and parameter-space constraints, as well as a handy two-page summary and Q&A section for a quick reference. A pedagogical, yet general and model independent guide, with examples from standard and non-standard particle Dark Matter models.

    hep-phLect.Notes Phys.(2022)·80 citations
30. 30*

    DarkELF: A python package for dark matter scattering in dielectric targets

    Simon Knapen🇨🇭 · Jonathan Kozaczuk🇺🇸 · Tongyan Lin🇺🇸

    We present a python package to calculate interaction rates of light dark matter in dielectric materials, including screening effects. The full response of the material is parametrized in the terms of the energy loss function (ELF) of material, which darkELF converts into differential scattering rates for both direct dark matter electron scattering and through the Migdal effect. In addition, darkELF can calculate the rate to produce phonons from sub-MeV dark matter scattering via the dark photon mediator, as well as the absorption rate for dark matter comprised of dark photons. The package includes precomputed ELFs for Al, ${\mathrm{Al}}_2{\mathrm{O}}_3$, GaAs, GaN, Ge, Si, ${\mathrm{SiO}}_2$, and ZnS, and allows the user to easily add their own ELF extractions for arbitrary materials.

    hep-phPRD(2022)·129 citations
31. 31*

    Contact interactions and top-philic scalar dark matter

    Alan S. Cornell🇿🇦 · Aldo Deandrea🇫🇷 · Thomas Flacke🇰🇷 · Benjamin Fuks🇫🇷 · Lara Mason🇿🇦

    We investigate the phenomenology of a scalar top-philic dark matter candidate when adding a dimension-five contact interaction term, as motivated by possible underlying extensions of the Standard Model such as composite Higgs models. We show that the presence of contact interactions can have a major impact on the dark matter relic density as well as on its direct and indirect detection prospects, while the collider phenomenology of the model is unaffected. This underlines the complementarity of collider and cosmological constraints on dark matter models.

    hep-phJHEP(2021)·8 citations
32. 32*

    SU($N$) Cartan-Weyl bases and color factors

    Duifje Maria van Egmond🇫🇷 · Urko Reinosa🇫🇷

    Constant temporal backgrounds have become a convenient tool for the discussion of continuum non-abelian gauge theories at finite temperature, as they provide a grasp on the confinement/deconfinement transition. It has been pointed that such backgrounds are better dealt with within so-called Cartan-Weyl color bases, rather than within the standard Cartesian bases. Here, we discuss the specificities of the evaluation of SU($N$) color factors within these bases, extending the discussion in Ref. [1].

    ↳ hep-thhep-ph2 citations
33. 33*

    Relativistic resistive dissipative magnetohydrodynamics from the relaxation time approximation

    Ankit Kumar Panda🇮🇳 · Ashutosh Dash🇮🇳 · Rajesh Biswas🇮🇳 · Victor Roy🇮🇳

    Here we derive the relativistic resistive dissipative second-order magnetohydrodynamic evolution equations using the Boltzmann equation, thus extending our work from the previous paper \href{https://link.springer.com/article/10.1007/JHEP03(2021)216}{JHEP 03 (2021) 216} where we considered the non-resistive limit. We solve the Boltzmann equation for a system of particles and antiparticles using the relaxation time approximation and the Chapman-Enskog like gradient expansion for the off-equilibrium distribution function, truncating beyond second-order. In the first order, the bulk and shear stress are independent of the electromagnetic field, however, the diffusion current, shows a dependence on the electric field. In the first order, the transport coefficients~(shear and bulk stress) are shown to be independent of the electromagnetic field. The diffusion current, however, shows a dependence on the electric field. In the second-order, the new transport coefficients that couple electromagnetic field with the dissipative quantities appear, which are different from those obtained in the 14-moment approximation~\cite{Denicol:2019iyh} in the presence of the electromagnetic field. Also we found out the various components of conductivity in this case.

    ↳ nucl-thhep-phphysics.flu-dynPRD(2021)·40 citations
34. 34*

    Excited states of massive fermions in a chiral gauge theory

    Jeff Greensite🇺🇸

    It is shown numerically, in a chiral U(1) gauge Higgs theory in which the left and right-handed fermion components have opposite U(1) charges, that the spectrum of gauge and Higgs fields surrounding a static fermion contains both a ground state and at least one stable excited state. To bypass the difficulties associated with dynamical fermions in a lattice chiral gauge theory we consider only static fermion sources in a quenched approximation, at fixed lattice spacing and couplings, and with a lattice action along the lines suggested long ago by Smit and Swift.

    ↳ hep-lathep-phhep-thPRD(2021)·5 citations
35. 35*

    To observe, or not to observe, quantum-coherent dark matter in the Milky Way, that is a question

    Tanja Rindler-Daller🇦🇹

    In recent years, Bose-Einstein-condensed dark matter (BEC-DM) has become a popular alternative to standard, collisionless cold dark matter (CDM). This BEC-DM - also called scalar field dark matter (SFDM) - can suppress structure formation and thereby resolve the small-scale crisis of CDM for a range of boson masses. However, these same boson masses also entail implications for BEC-DM substructure within galaxies, especially within our own Milky Way. Observational signature effects of BEC-DM substructure depend upon its unique quantum-mechanical features and have the potential to reveal its presence. Ongoing efforts to determine the dark matter substructure in our Milky Way will continue and expand considerably over the next years. In this contribution, we will discuss some of the existing constraints and potentially new ones with respect to the impact of BEC-DM onto baryonic tracers. Studying dark matter substructure in our Milky Way will soon resolve the question, whether dark matter behaves classical or quantum on scales of $\lesssim 1$ kpc.

    ↳ astro-ph.GAastro-ph.COcond-mat.quant-gashep-ph+1Front. Astron. Space Sci. Vol.8, article …·1 citation
36. 36*

    Hydrodynamic Attractor in a Hubble Expansion

    Zhiwei Du🇨🇳 · Xu-Guang Huang🇨🇳 · Hidetoshi Taya🇯🇵

    We analytically investigate hydrodynamic attractor solutions in both Müller-Israel-Stewart (MIS) and kinetic theories in a viscous fluid system undergoing a Hubble expansion with a fixed expansion rate. We show that the gradient expansion for the MIS theory and the Chapman-Enskog expansion for the Boltzmann equation within the relaxation time approximation are factorially divergent and obtain hydrodynamic attractor solutions by applying the Borel resummation technique to those asymptotic divergent series. In both theories, we find that the hydrodynamic attractor solutions are globally attractive and only the first-order non-hydrodynamic mode exists. We also find that the hydrodynamic attractor solutions in the two theories disagree with each other when gradients become large, and that the speed of the attraction is different. Similarities and differences from hydrodynamic attractors in the Bjorken and Gubser flows are also discussed. Our results push the idea of far-from-equilibrium hydrodynamics in systems undergoing a Hubble expansion.

    ↳ nucl-thgr-qchep-phhep-thPRD(2021)·17 citations
37. 37*

    Phase Structures and Transitions of Quintessence Surrounding RN Black Holes in a Grand Canonical Ensemble

    Yuchen Huang🇨🇳 · Hongmei Jing🇨🇳 · Jun Tao🇨🇳 · Feiyu Yao🇨🇳

    Considering a grand canonical ensemble, we study the phase structures and transitions of RN black holes surrounded by quintessence dark energy on two different boundary conditions, namely AdS space and a Dirichlet wall. For AdS space, under the condition of fixed temperature and potential, as the temperature increases for lower potential, the black hole undergoes a first-order phase transition, while for higher potential, no phase transition occurs. There are two different regions in the parameter space. For the Dirichlet wall, on which the temperature and potential are fixed and the state parameter of quintessence $\omega =-2/3$ is analyzed in detail. Then, three different physically allowed regions in the parameter space of the black hole are well studied. As the temperature rises, a first-order phase transition and a second-order phase transition may occur. In this case, there are nine regions in the parameter space, which is obviously distinct from the case of AdS space.

    ↳ gr-qchep-phCPC(2021)·17 citations
38. 38*

    On the Existence of the Coleman Instantons

    Viatcheslav Mukhanov🇩🇪 · Alexander Sorin🇷🇺

    We identify infinite classes of potentials for which the Coleman instantons do not exist. For these potentials, the decay of a false vacuum must be described by the new instantons introduced in [7,8].

    ↳ hep-thgr-qchep-phmath-ph+2JCAP(2021)·8 citations
39. 39*

    Dyson-Schwinger equation approach to Lorentz Symmetry Breaking with finite temperature and chemical potential

    Y.M.P. Gomes🇧🇷

    In this work, we investigate the dynamical breakdown of Lorentz symmetry in 4 dimensions by the condensation of a fermionic field described by a Dirac Lagrangian with a four-fermion interaction. Using the Keldysh formalism we show that the Lorentz symmetry breaking modifies the Dyson-Schwinger equations of the fermionic propagator. We analyze the nonperturbative solutions for the Dyson-Schwinger equations using the combination of the rainbow and quenched approximations and show that, in equilibrium, the Lorentz symmetry breakdown can occur in the strong coupling regime and new features arise from this approach. Finally, we analyze the contributions of temperature and chemical potential and find the respective phase diagram of the model and analyze the dependence of the critical temperature and chemical potential as functions of the coupling constant.

    ↳ hep-thhep-phPRD(2021)·3 citations
40. 40*

    Via Machinae: Searching for Stellar Streams using Unsupervised Machine Learning

    David Shih🇺🇸 · Matthew R. Buckley🇺🇸 · Lina Necib🇺🇸 · John Tamanas🇺🇸

    We develop a new machine learning algorithm, Via Machinae, to identify cold stellar streams in data from the Gaia telescope. Via Machinae is based on ANODE, a general method that uses conditional density estimation and sideband interpolation to detect local overdensities in the data in a model agnostic way. By applying ANODE to the positions, proper motions, and photometry of stars observed by Gaia, Via Machinae obtains a collection of those stars deemed most likely to belong to a stellar stream. We further apply an automated line-finding method based on the Hough transform to search for line-like features in patches of the sky. In this paper, we describe the Via Machinae algorithm in detail and demonstrate our approach on the prominent stream GD-1. Though some parts of the algorithm are tuned to increase sensitivity to cold streams, the Via Machinae technique itself does not rely on astrophysical assumptions, such as the potential of the Milky Way or stellar isochrones. This flexibility suggests that it may have further applications in identifying other anomalous structures within the Gaia dataset, for example debris flow and globular clusters.

    ↳ astro-ph.GAhep-phphysics.data-anMNRAS(2021)·41 citations
41. 41*

    CMB $\mu T$ cross-correlations as a probe of PBH scenarios

    Ogan Özsoy🇨🇿 · Gianmassimo Tasinato🇬🇧

    We propose a new method for probing inflationary models of primordial black hole (PBH) production, using only CMB physics at relatively large scales. In PBH scenarios, the primordial power spectrum profile for curvature perturbations is characterized by a pronounced dip, followed by a rapid growth towards small scales, leading to a peak responsible for PBH formation. We focus on scales around the dip that are well separated from the peak to analytically compute expressions for the curvature power spectrum and bispectrum. The size of the squeezed bispectrum is enhanced at the position of the dip, and it acquires a characteristic scale dependence that can be probed by cross-correlating CMB $\mu$-distortions and temperature fluctuations. We quantitatively study the properties of such cross-correlations and how they depend on the underlying model, discussing how they can be tested by the next generation of CMB $\mu$-distortion experiments. This method allows one to experimentally probe inflationary PBH scenarios using well-understood CMB physics, without considering non-linearities associated with PBH formation and evolution.

    ↳ astro-ph.COhep-phhep-thPRD(2021)·26 citations
42. 42*

    Dark Sector to Restore Cosmological Concordance

    Itamar J. Allali🇺🇸 · Mark P. Hertzberg🇺🇸 · Fabrizio Rompineve🇺🇸

    We develop a new phenomenological model that addresses current tensions between observations of the early and late Universe. Our scenario features: (i) a decaying dark energy fluid (DDE), which undergoes a transition at $z\sim 5,000$, to raise today's value of the Hubble parameter -- addressing the $H_0$ tension, and (ii) an ultra-light axion (ULA), which starts oscillating at $z\gtrsim 10^4$, to suppress the matter power spectrum -- addressing the $S_8$ tension. Our Markov Chain Monte Carlo analyses show that such a Dark Sector model fits a combination of Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations, and Large Scale Structure (LSS) data slightly better than the $\Lambda$CDM model, while importantly reducing both the $H_0$ and $S_8$ tensions with late universe probes ($\lesssim 3\sigma$). Combined with measurements from cosmic shear surveys, we find that the discrepancy on $S_8$ is reduced to the $1.4\sigma$ level, and the value of $H_0$ is further raised. Adding local supernovae measurements, we find that the $H_0$ and $S_8$ tensions are reduced to the $1.4\sigma$ and $1.2\sigma$ level respectively, with a significant improvement $\Delta {\chi }^2\simeq -18$ compared to the $\Lambda$CDM model. With this complete dataset, the DDE and ULA are detected at $\simeq 4\sigma$ and $\simeq 2\sigma$, respectively. We discuss a possible particle physics realization of this model, with a dark confining gauge sector and its associated axion, although embedding the full details within microphysics remains an urgent open question. Our scenario will be decisively probed with future CMB and LSS surveys.

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