Tue·Feb 4, 2020Tuesday·February 4, 2020

1. 01*

   Degenerate Sub-keV Fermion Dark Matter from a Solution to the Hubble Tension

   Gongjun Choi🇨🇳 · Motoo Suzuki🇨🇳 · Tsutomu T. Yanagida🇯🇵

   We present a dark sector model addressing both the Hubble tension and the core-cusp problem. The model is based on a hidden Abelian gauge symmetry group with some chiral fermions required by the anomaly cancellation conditions, producing a candidate for the decaying fermion dark matter as a solution to the Hubble tension. Moreover, the sub-keV mass regime and the thermal history of the dark sector help the dark matter candidate resolve the core-cusp problem occurring in the standard $\Lambda$CDM cosmology.

   hep-phastro-ph.COastro-ph.GAPRD(2020)·31 citations
2. 02*

   Nonlinear realization of chiral symmetry breaking in holographic soft wall models

   Alfonso Ballon-Bayona🇧🇷 · Luis A. H. Mamani🇧🇷

   We investigate nonlinear extensions of the holographic soft wall model proposed by Karch, Katz, Son and Stephanov \cite{Karch:2006pv} with a positive quadratic dilaton. We consider a Higgs potential for the tachyonic field that brings a more natural realisation of chiral symmetry breaking in the infrared regime. Utilising the AdS/CFT dictionary and holographic renormalisation we find the chiral condensate as a function of the quark mass. The nonlinearity of the Higgs potential leads to a nonlinear relation between the chiral condensate and the quark mass. Solving the effective Schrödinger equations for the field perturbations we estimate meson masses and decay constants and evaluate their dependence on the quark mass. In the axial and pseudoscalar sector we find an interesting behaviour for the decay constants as the quark mass increases. We also investigate the effect of a 5d running mass for the tachyonic field. We conclude that nonlinear soft wall models with a Higgs potential for the tachyon and a positive quadratic dilaton do not provide spontaneous symmetry breaking in the chiral limit.

   hep-phhep-thPRD(2020)·27 citations
3. 03*

   Effects of the transverse coherence length in relativistic collisions

   Dmitry V. Karlovets🇷🇺 · Valeriy G. Serbo🇷🇺

   Effects of the quantum interference in collisions of particles have a twofold nature: they arise because of the auto-correlation of a complex scattering amplitude and due to spatial coherence of the incoming wave packets. Both these effects are neglected in a conventional scattering theory dealing with the delocalized plane waves, although they sometimes must be taken into account in particle and atomic physics. Here, we study the role of a transverse coherence length of the packets, putting special emphasis on the case in which one of the particles is twisted, that is, it carries an orbital angular momentum $\ell \hslash$. In $ee,ep$, and $pp$ collisions the interference results in corrections to the plane-wave cross sections, usually negligible at the energies $\sqrt{s}\gg 1$ GeV but noticeable for smaller ones, especially if there is a twisted hadron with $|\ell |>10^3$ in initial state. Beyond the perturbative QCD, these corrections become only moderately attenuated allowing one to probe a phase of the hadronic amplitude as a function of $s$ and $t$. In this regime, the coherence effects can compete with the loop corrections in QED and facilitate testing the phenomenological models of the strong interaction at intermediate and low energies.

   hep-phquant-phPRD(2020)·23 citations
4. 04*

   Mass prediction for the last discovered member of the axial-vector nonet with quantum numbers J${}^{PC}=1^{+-}$

   Mihail Chizhov🇧🇬 · Momchil Naydenov🇧🇬

   In this paper we have shown that the novel mass relation among the vector states, $\varphi (1020)$ and $\varphi (1680)$, with quantum numbers J${}^{PC}=1^{--}$ and axial-vector strangeonium state $h_1(s\bar{s})$ with quantum numbers $1^{+-}$ is also valid for nonzero current quark mass. This relation predicts the mass of recently discovered $h_1(s\bar{s})$ state by the Collaboration BESIII within experimental accuracy.

   hep-phhep-exhep-latJETP Lett.(2020)·3 citations
5. 05*

   Oscillating Neutrinos and Majorana Neutrino Masses

   Harald Fritzsch🇩🇪

   The texture zero mass matrices for the leptons and the seesaw mechanism are used to derive relations between the matrix elements of the lepton mixing matrix and the ratios of the neutrino masses.

   hep-phUniverse(2020)·2 citations
6. 06*

   Formulation for renormalon-free perturbative predictions beyond large-${\beta }_0$ approximation

   Hiromasa Takaura🇯🇵

   We present a formulation to give renormalon-free predictions consistently with fixed order perturbative results. The formulation has a similarity to Lee's method in that the renormalon-free part consists of two parts: one is given by a series expansion which does not contain renormalons and the other is the real part of the Borel integral of a singular Borel transform. The main novel aspect is to evaluate the latter object using a dispersion relation technique, which was possible only in the large-${\beta }_0$ approximation. Here, we introduce an "ambiguity function," which is defined by inverse Mellin transform of the singular Borel transform. With the ambiguity function, we can rewrite the Borel integral in an alternative formula, which allows us to obtain the real part using analytic techniques similarly to the case of the large-${\beta }_0$ approximation. We also present detailed studies of renormalization group properties of the formulation. As an example, we apply our formulation to the fixed-order result of the static QCD potential, whose closest renormalon is already visible.

   hep-phhep-lathep-thJHEP(2020)·13 citations
7. 07*

   Chiral symmetry restoration and the thermal $f_0(500)$ state

   Andrea Vioque-Rodríguez🇪🇸 · Angel Gómez Nicola🇪🇸

   We analize the role played by the thermal $f_0(500)$ state or $\sigma$ in chiral symmetry restoration. The temperature corrections to the spectral properties of that state are included in order to provide a better description of the scalar susceptibility ${\chi }_S$ around the transition region. We use the Linear Sigma Model to establish the relation between ${\chi }_S$ and the $\sigma$ propagator, which is used as a benchmark to test the approach where ${\chi }_S$ is saturated by the $f_0(500)$ inverse self-energy. Within such saturation approach, a peak for ${\chi }_S$ around the chiral transition is obtained when considering the $f_0(500)$ generated as a $\pi \pi$ scattering pole within Unitarized Chiral Perturbation Theory at finite temperature. That approach yields results complying with lattice data when the uncertainties of the low-energy constants are taken into account. Those uncertainties and the unitarization method are used to check the robustness of this approximation. Finally, we will discuss some recent results within the chiral lagrangian framework related to the topological susceptibility and its connection with chiral and $U_A(1)$ restoration.

   hep-phPoS(2020)·0 citations
8. 08*

   FindBounce: package for multi-field bounce actions

   Victor Guada🇸🇮 · Miha Nemevšek🇸🇮 · Matevž Pintar🇸🇱

   We are launching FindBounce, a Mathematica package for the evaluation of the Euclidean bounce action that enters the decay rate of metastable states in quantum and thermal field theories. It is based on the idea of polygonal bounces, which is a semi-analytical approach to solving the bounce equation by discretizing the potential into piecewise linear segments. This allows for a fast and robust evaluation of arbitrary potentials with specified precision and any number of scalar fields. Time cost grows linearly with the number of fields and/or the number of segments. Computation with 20 fields takes $\sim 2$ seconds with $0.5\%$ accuracy of the action. The FindBounce function is simple to use with the native Mathematica look and feel, it is easy to install, and comes with detailed documentation and physical examples, such as the calculation of the nucleation temperature. We also provide timing benchmarks with comparisons to existing tools, where applicable.

   hep-phastro-ph.COComput.Phys.Commun.(2020)·141 citations
9. 09*

   Search for the $H\to {\text{W}}^{+}{\text{W}}^{-}$ process at the LHeC Experiment

   Hollis Williams🇬🇧

   We consider the decay of the Higgs boson to W${}^{+}$ W${}^{-}$ at a proposed Large Hadron Electron Collider and determine the likelihood of detecting a signal for the Higgs mass from its decay product W jets by imposing cuts to select candidate jet pairs and optimizing the value of the angular separation $\Delta R$. It was found that at the LHeC experiment (CM energy $\sqrt{s}=1.3$ TeV and luminosity of 100 fb${}^{-1}$ per year), the highest efficiency is obtained with $\Delta R=0.4$, along with a selection scheme of $|\Delta \eta |<1,10<m<85$ GeV, $p_T$ of jets 1 and 2 between $10-20$ GeV and $p_T$ of jets 3 and 4 $>10$ GeV: this led to an efficiency between $7.1-7.5\%$ for finding the invariant 4-jet mass in a mass region $<140$ GeV. Under signal-to-background comparison, the signal showed a $3.8\sigma$ excess compared to the charged current W${}^{-}$ background.

   hep-phActa Phys.Polon.B(2020)·0 citations
10. 10*

    Groomed jet mass at high precision

    Adam Kardos🇭🇺 · Andrew J. Larkoski🇺🇸 · Zoltán Trócsányi🇭🇺

    We present predictions of the distribution of groomed heavy jet mass in electron-positron collisions at the next-to-next-to-leading order accuracy matched with the resummation of large logarithms to next-to-next-to-next-to-leading logarithmic accuracy. Resummation at this accuracy is possible through extraction of necessary two-loop constants and three-loop anomalous dimensions from fixed-order codes.

    hep-phhep-exPLB(2020)·47 citations
11. 11*

    Free energy of a Holonomous Plasma

    Chris P. Korthals Altes🇫🇷 · Hiromichi Nishimura🇯🇵 · Robert D. Pisarski🇺🇸 · Vladimir V. Skokov🇺🇸

    At a nonzero temperature T, a constant field ${\overline{A}}_0\sim T/g$ generates nontrivial eigenvalues of the thermal Wilson line. We discuss contributions to the free energy of such a holonomous plasma when the coupling constant, $g$, is weak. We review the computation to $\sim g^2$ by several alternate methods, and show that gauge invariant sources, which are nonlinear in the gauge potential $A_0$, generate novel contributions to the gluon self energy at $\sim g^2$. These ensure the gluon self energy remains transverse to $\sim g^2$, and are essential in computing contributions to the free energy at $\sim g^3$ for small holonomy, ${\overline{A}}_0\sim T$. We show that the contribution $\sim g^3$ from off-diagonal gluons is discontinuous as the holonomy vanishes. The contribution from diagonal gluons is continuous as the holonomy vanishes, but sharply constrains the possible sources which generate nonzero holonomy, and must involve an infinite number of Polyakov loops.

    hep-phhep-latnucl-thPRD(2020)·16 citations
12. 12*

    Fermion Mass Hierarchies from Modular Symmetry

    Simon J.D. King🇬🇧 · Stephen F. King🇬🇧

    We show how quark and lepton mass hierarchies can be reproduced in the framework of modular symmetry. The mechanism is analogous to the Froggatt-Nielsen (FN) mechanism, but without requiring any Abelian symmetry to be introduced, nor any Standard Model (SM) singlet flavon to break it. The modular weights of fermion fields play the role of FN charges, and SM singlet fields with non-zero modular weight called weightons play the role of flavons. We illustrate the mechanism by analysing $A_4$ (modular level 3) models of quark and lepton (including neutrino) masses and mixing, with a single modulus field. We discuss two examples in some detail, both numerically and analytically, showing how both fermion mass and mixing hierarchies emerge from different aspects of the modular symmetry.

    hep-phJHEP(2020)·117 citations
13. 13*

    Signature of neutrino mass hierarchy in gravitational lensing

    Himanshu Swami🇮🇳 · Kinjalk Lochan🇮🇳 · Ketan M. Patel🇮🇳

    In flat spacetime, the vacuum neutrino flavour oscillations are known to be sensitive only to the difference between the squared masses, and not to the individual masses, of neutrinos. In this work, we show that the lensing of neutrinos induced by a gravitational source substantially modifies this standard picture and it gives rise to a novel contribution through which the oscillation probabilities also depend on the individual neutrino masses. A gravitating mass located between a source and a detector deflects the neutrinos in their journey, and at a detection point, neutrinos arriving through different paths can lead to the phenomenon of interference. The flavour transition probabilities computed in the presence of such interference depend on the individual masses of neutrinos whenever there is a non-zero path difference between the interfering neutrinos. We demonstrate this explicitly by considering an example of weak lensing induced by a Schwarzschild mass. Through the simplest two flavour case, we show that the oscillation probability in the presence of lensing is sensitive to the sign of $\Delta m^2=m_2^2-m_1^2$, for non-maximal mixing between two neutrinos, unlike in the case of standard vacuum oscillation in flat spacetime. Further, the probability itself oscillates with respect to the path difference and the frequency of such oscillations depends on the absolute mass scale $m_1$ or $m_2$. We also give results for realistic three flavour case and discuss various implications of gravitationally modified neutrino oscillations and means of observing them.

    hep-phastro-ph.SRgr-qcPRD(2020)·34 citations
14. 14*

    Fate of Light Scalar Mesons

    N.N. Achasov🇷🇺

    It is shown that all predictions for the light scalars, based on their four-quark nature, are supported by experiment. The future research program is outlined also.

    hep-phhep-exnucl-thPhys.Part.Nucl.(2020)·8 citations
15. 15*

    Consistency checks for two-body finite-volume matrix elements: II. Perturbative systems

    Raúl A. Briceño🇺🇸 · Maxwell T. Hansen🇨🇭 · Andrew W. Jackura🇺🇸

    Using the general formalism presented in Refs. [1,2], we study the finite-volume effects for the $2+\mathcal{J}\to 2$ matrix element of an external current coupled to a two-particle state of identical scalars with perturbative interactions. Working in a finite cubic volume with periodicity $L$, we derive a $1/L$ expansion of the matrix element through $\mathcal{O}(1/L^5)$ and find that it is governed by two universal current-dependent parameters, the scalar charge and the threshold two-particle form factor. We confirm the result through a numerical study of the general formalism and additionally through an independent perturbative calculation. We further demonstrate a consistency with the Feynman-Hellmann theorem, which can be used to relate the $1/L$ expansions of the ground-state energy and matrix element. The latter gives a simple insight into why the leading volume corrections to the matrix element have the same scaling as those in the energy, $1/L^3$, in contradiction to earlier work, which found a $1/L^2$ contribution to the matrix element. We show here that such a term arises at intermediate stages in the perturbative calculation, but cancels in the final result.

    ↳ hep-lathep-phnucl-thPRD(2020)·29 citations
16. 16*

    Variation of fundamental constants and white dwarfs

    Susana J. Landau🇦🇷

    Theories that attempt to unify the four fundamental interactions and alternative theories of gravity predict time and/or spatial variation of the fundamental constants of nature. Different versions of these theories predict different behaviours for these variations. In consequence, experimental and observational bounds are an important tool to check the validity of such proposals. In this paper, we review constraints on the possible variation of the fundamental constants from astronomical observations and geophysical experiments designed to test the constancy of the fundamental constants of nature over different timescales. We also focus on the limits that can be obtained from white dwarfs, which can constrain the variation of the constants with the gravitational potential.

    ↳ astro-ph.COhep-phIAU Symp.(2019)·12 citations
17. 17*

    Stealth dark matter and gravitational waves

    David Schaich (for the Lattice Strong Dynamics Collaboration)🇬🇧

    I present first results from ongoing lattice investigations into the finite-temperature dynamics of stealth dark matter, which adds to the standard model a new SU(4) gauge sector with four moderately heavy fundamental fermions. This work by the Lattice Strong Dynamics Collaboration builds on past studies of direct detection and collider searches for stealth dark matter, by analyzing the early-universe SU(4) confinement transition, which produces a stochastic background of gravitational waves if it is first order. In addition to delineating the parameter space in which a first-order transition is observed, I discuss the quantities we are analyzing in order to predict the resulting gravitational-wave spectrum.

    ↳ hep-lathep-phPoS(2020)·2 citations
18. 18*

    Dynamical simulation on production of ${\mathrm{W}}^{\pm }$ and ${\mathrm{Z}}^0$ bosons in p-p, p-Pb (Pb-p), and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with PACIAE

    Dai-Mei Zhou🇨🇳 · Yu-Liang Yan🇨🇳 · Liang Zheng🇨🇳 · Ming-Rui Zhao🇨🇳 · Xiao-Mei Li🇨🇳 · Xiao-Ming Zhang🇨🇳 · Xu Cai🇨🇳 · Ben-Hao Sa🇨🇳

    In this paper, production of ${\mathrm{W}}^{\pm }$ and ${\mathrm{Z}}^0$ vector bosons in p-p, p-Pb (Pb-p), and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is dynamically simulated with a parton and hadron cascade model PACIAE. ALICE data of ${\mathrm{Z}}^0$ production is found to be reproduced fairly well. A prediction for ${\mathrm{W}}^{\pm }$ production is given in the same collision systems, at the same energy and at the same energy. An interesting isospin-effect is observed in the sign-change of ${\mu }^{\pm }$ charge asymmetry in pp, pn, np, and nn collisions and in minimum bias p-Pb, Pb-p and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, respectively.

    ↳ nucl-thhep-ph0 citations
19. 19*

    Charm-hadron production in $pp$ and AA collisions

    Min He🇨🇳 · Ralf Rapp🇺🇸

    Recent measurements of various charm-hadron ratios in $pp$, $p$-Pb and Pb-Pb collisions at the LHC have posed challenges to the theoretical understanding of heavy-quark hadronization. The ${\Lambda }_c/D^0$ ratio in $pp$ and $p$-Pb collisions shows larger values than those found in $e^{+}{e}^{-}$ and $ep$ collisions and predicted by Monte-Carlo event generators based on string fragmentation, at both low and intermediate transverse momenta ($p_T$). In AA collisions, the $D_s/D$ ratio is significantly enhanced over its values in $pp$, while the ${\Lambda }_c/D^0$ data indicates a further enhancement at intermediate $p_T$. Here, we report on our recent developments for a comprehensive description of the charm hadrochemistry and transport in $pp$ and $AA$ collisions. For $pp$ collisions we find that the discrepancy between the ${\Lambda }_c/D^0$ data and model predictions is much reduced by using a statistical hadronization model augmented by a large set of "missing" states in the charm-baryon spectrum, contributing to the ${\Lambda }_c$ via decay feeddown. For $AA$ collisions, we develop a 4-momentum conserving resonance recombination model for charm-baryon formation implemented via event-by-event simulations that account for space-momentum correlations (SMCs) in transported charm- and thermal light-quark distributions. The SMCs, together with the augmented charm-baryon states, are found to play an important role in describing the baryon-to-meson enhancement at intermediate momenta. We emphasize the importance of satisfying the correct (relative) chemical equilibrium limit when computing the charm hadrochemistry and its momentum dependence with coalescence models.

    ↳ nucl-thhep-phNPA(2021)·2 citations
20. 20*

    Annual modulations from secular variations: relaxing DAMA?

    Dario Buttazzo🇮🇹 · Paolo Panci🇮🇹 · Nicola Rossi🇮🇹 · Alessandro Strumia🇮🇹

    The DAMA collaboration reported an annually modulated rate with a phase compatible with a Dark Matter induced signal. We point out that a slowly varying rate can bias or even simulate an annual modulation if data are analyzed in terms of residuals computed by subtracting approximately yearly averages starting from a fixed date, rather than a background continuous in time. In the most extreme case, the amplitude and phase of the annual modulation reported by DAMA could be alternatively interpreted as a decennial growth of the rate. This possibility appears mildly disfavoured by a detailed study of the available data, but cannot be safely excluded. In general, a decreasing or increasing rate could partially reduce or enhance a true annual modulation, respectively. The issue could be clarified by looking at the full time-dependence of the DAMA total rate, not explicitly published so far.

    ↳ hep-exastro-ph.COhep-phJHEP(2020)·30 citations
21. 21*

    Cosmological parameter measurement and neutral hydrogen 21 cm sky survey with the Square Kilometre Array

    Yidong Xu🇨🇳 · Xin Zhang🇨🇳

    In order to precisely measure the cosmological parameters and answer the fundamental questions in cosmology, it is necessary to develop new, powerful cosmological probes, in addition to the proposed next-generation optical survey projects. The neutral hydrogen 21 cm sky surveys will provide a promising tool to study the late-universe evolution, helping shed light on the nature of dark energy. The Square Kilometre Array is the largest radio telescope in the world to be constructed in the near future, and it will push the 21 cm cosmology into a new era and greatly promote the development of cosmology in the forthcoming decades.

    ↳ astro-ph.COastro-ph.GAgr-qchep-phSCPMA(2020)·25 citations
22. 22*

    Effects of dark matter on the nuclear and neutron star matter

    H. C. Das🇮🇳 · Ankit Kumar🇮🇳 · Bharat Kumar🇯🇵 · S. K. Biswal🇨🇳 · Takashi Nakatsukasa🇯🇵 · Ang Li🇨🇳 · S. K. Patra🇮🇳

    We study the dark matter effects on the nuclear matter parameters characterising the equation of states of super dense neutron-rich nucleonic-matter. The observables of the nuclear matter, i.e. incompressibility, symmetry energy and its higher-order derivatives in the presence dark matter for symmetric and asymmetric nuclear matter are analysed with the help of an extended relativistic mean-field model. The calculations are also extended to beta-stable matter to explore the properties of the neutron star. We analyse the dark matter effects on symmetric nuclear matter, pure neutron matter and neutron star using NL3, G3 and IOPB-I forces. The binding energy per particle and pressure are calculated with and without considering the dark matter interaction with the nuclear matter systems. The influences of dark matter are also analysed on the symmetry energy and its different coefficients. The incompressibility and the skewness parameters are affected considerably due to the presence of dark matter in the nuclear matter medium. We extend the calculations to the neutron star and find its mass, radius and the moment of inertia for static and rotating neutron star with and without dark matter contribution. The mass of the rotating neutron star is considerably changing due to rapid rotation with the frequency in the mass-shedding limit. The effects of dark matter are found to be important for some of the nuclear matter parameters, which are crucial for the properties of astrophysical objects.

    ↳ nucl-thastro-ph.HEhep-phMNRAS(2020)·115 citations
23. 23*

    Thermal modifications of quarkonia and heavy quark diffusion from a comparison of continuum-extrapolated lattice results to perturbative QCD

    Anna-Lena Lorenz🇩🇪 · Heng-Tong Ding🇨🇳 · Olaf Kaczmarek🇩🇪 · Hiroshi Ohno🇯🇵 · Hauke Sandmeyer🇩🇪 · Hai-Tao Shu🇩🇪

    We investigate the in-medium modifications of heavy quarkonia in the vector channel and the heavy quark diffusion coefficient by comparing Euclidean correlators from the lattice to a perturbative spectral function. On the lattice side, we work with continuum extrapolated data from four different large and fine lattices with Clover-improved Wilson fermions in the quenched approximation at five temperatures (0.75, 1.1, 1.3, 1.5 and 2.25$T_c$). On the perturbative side, we use a combination of pNRQCD and vacuum asymptotics to describe the spectral function. After accounting for systematic errors, we obtain a spectral function that is suited to describe the bound state region. This spectral function describes charmonium well without a resonance peak at any of our analyzed temperatures above $T_c$, while we observe a thermally broadened resonance peak for bottomonium that is only melted at our largest temperature, $2.25T_c$. For the transport contribution we assume a Breit-Wigner shaped peak and find that the drag coefficient of charm quarks is larger than that of bottom quarks.

    ↳ hep-lathep-phnucl-exnucl-thPoS(2020)·5 citations
24. 24*

    CMB and BBN constraints on evaporating primordial black holes revisited

    Sandeep Kumar Acharya🇮🇳 · Rishi Khatri🇮🇳

    We derive new CMB anisotropy power spectrum and BBN constraints for evaporating primordial black holes by explicitly solving the electromagnetic particle cascades of emitted particles and the deposition of this emitted energy to the background baryon-photon plasma. We show that the CMB anisotropies can provide stronger constraints compared to BBN and CMB spectral distortions on black holes with masses as small as $M_{\mathrm{BH}}=1.1\times 10^{13}$g, a slightly smaller mass than what has been considered in literature until now. We also show that, with more up-to-date data on abundances of deuterium and helium-3, BBN constraints are strengthened significantly.

    ↳ astro-ph.COastro-ph.HEhep-phJCAP(2020)·123 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.