Wed·Jul 22, 2020Wednesday·July 22, 2020

1. 01*

   Occurrence of Tachyonic Preheating in the Mixed Higgs-$R^2$ Model

   Minxi He🇯🇵 · Ryusuke Jinno🇩🇪 · Kohei Kamada🇯🇵 · Alexei A. Starobinsky🇯🇵 · Jun'ichi Yokoyama🇯🇵

   It has recently been suggested that at the post-inflationary stage of the mixed Higgs-$R^2$ model of inflation efficient particle production can arise from the tachyonic instability of the Higgs field. It might complete the preheating of the Universe if appropriate conditions are satisfied, especially in the Higgs-like regime. In this paper, we study this behavior in more depth, including the conditions for occurrence, analytical estimates for the maximal efficiency, and the necessary degree of fine-tuning among the model parameters to complete preheating by this effect. We find that the parameter sets that cause the most efficient tachyonic instabilities obey simple laws in both the Higgs-like regime and the $R^2$-like regime, respectively. We then estimate the efficiency of this instability. In particular, even in the deep $R^2$-like regime with a small non-minimal coupling, this effect is strong enough to complete preheating although a severe fine-tuning is required among the model parameters. We also estimate how much fine-tuning is needed to complete preheating by this effect. It is shown that the fine-tuning of parameters for the sufficient particle production is at least $<\mathcal{O}(0.1)$ in the deep Higgs-like regime with a large scalaron mass, while it is more severe $\sim \mathcal{O}(10^{-4})-\mathcal{O}(10^{-5})$ in the $R^2$-like regime with a small non-minimal coupling.

   hep-phastro-ph.COgr-qcJCAP(2021)·58 citations
2. 02*

   The Higgs field and early universe cosmology: a (brief) review

   Bart Horn🇺🇸

   We review and discuss recent work exploring the implications of the Higgs field for early universe cosmology, and vice versa. Depending on the model under consideration the Higgs may be one of a few scalar fields determining the evolution and fate of the Universe, or the Higgs field may be connected to a rich sector of scalar moduli with complicated dynamics. In particular we look at the potential consequences of the Higgs field for inflation and its predictions, for the (meta)stability of the Standard Model vacuum, and for the existence of dynamical selection mechanisms in the landscape.

   hep-phastro-ph.COhep-thMDPI Physics(2020)·22 citations
3. 03*

   Dark Matter Particle in QCD

   Glennys R. Farrar🇺🇸 · Zihui Wang🇺🇸 · Xingchen Xu🇺🇸

   We report on the possibility that the Dark Matter particle is a stable, neutral, as-yet-undiscovered hadron in the standard model. The existence of a compact color-flavor-spin singlet sexaquark (S, uuddss) with mass ~2m_p, is compatible with current knowledge. The S interacts with baryons primarily via a Yukawa interaction of coupling strength alpha_SN, mediated by omega and phi vector mesons having mass ~1 GeV. If it exists, the S is a very attractive DM candidate. The relic abundance of S Dark Matter (SDM) is established when the Universe transitions from the quark-gluon plasma to the hadronic phase at ~150 MeV and is in remarkable agreement with the observed Omega_DM/Omega_b = 5.3+-0.1; this is a no-free-parameters result because the relevant parameters are known from QCD. Survival of this relic abundance to low temperature requires the breakup amplitude gtilde <~ 2 10^-6, comfortably compatible with theory expectations and observational bounds because the breakup amplitude is dynamically suppressed and many orders of magnitude smaller, as we show. The scattering cross section can differ by orders of magnitude from Born approximation, depending on alpha_SN, requiring reanalysis of observational limits. We use direct detection experiments and cosmological constraints to determine the allowed region of alpha_SN. For a range of allowed values, we predict exotic nuclear isotopes at a detectable level with mass offset ~2 amu. The most promising approaches for detecting the sexaquark in accelerator experiments are to search for a long-interaction-length neutral particle component in the central region of relativistic heavy ion collisions or using a beam-dump setup, and to search for evidence of missing particle production characterized by unbalanced baryon number and strangeness using Belle-II or possibly GLUEX at J-Lab.

   hep-phastro-ph.CO28 citations
4. 04*

   Technicolor coupled models

   A. A. Natale🇧🇷 · A. Doff🇧🇷

   When technicolor (TC), QCD, extended technicolor (ETC) and other interactions become coupled through their different Schwinger-Dyson equations, the solution of these equations are modified compared to those of the isolated equations. The change in the self-energies is similar to that obtained in the presence of four-fermion interactions, but without their ad hoc inclusion in the theory. In this case the TC and QCD self-energies decrease logarithmically with the momenta, which allows us to build models where ETC boson masses can be pushed to very high energies, and do not lead to undesirable flavor changing interactions. Viable TC models may be built along this line including a necessary horizontal symmetry. The different fermionic mass scales are dictated by the different strong interactions. Pseudo-Goldstone bosons acquire large masses in this class of models.

   hep-phPoS(2020)·0 citations
5. 05*

   Scotogenic dark matter in an orbifold theory of flavor

   Francisco J. de Anda🇲🇽 · Ignatios Antoniadis🇫🇷 · José W. F. Valle🇪🇸 · Carlos A. Vaquera-Araujo🇲🇽

   We propose a flavour theory in which the family symmetry results naturally from a six-dimensional orbifold compactification. "Diracness" of neutrinos is a consequence of the spacetime dimensionality, and the fact that right-handed neutrinos live in the bulk. Dark matter is incorporated in a scotogenic way, as a result of an auxiliary ${\mathbb{Z}}_3$ symmetry, and its stability is associated to the conservation of a "dark parity" symmetry. The model leads naturally to a "golden" quark-lepton mass relation.

   hep-phhep-thJHEP(2020)·3 citations
6. 06*

   Inelastic Fermion Dark Matter Origin of XENON1T Excess with Muon $(g-2)$ and Light Neutrino Mass

   Debasish Borah🇮🇳 · Satyabrata Mahapatra🇮🇳 · Dibyendu Nanda🇮🇳 · Narendra Sahu🇮🇳

   Motivated by the recently reported excess in electron recoil events by the XENON1T collaboration, we propose an inelastic fermion dark matter (DM) scenario within the framework of a gauged $L_{\mu }-L_{\tau }$ extension of the standard model which can also accommodate tiny neutrino masses as well as anomalous muon magnetic moment $(g-2{)}_{\mu }$. A Dirac fermion DM, naturally stabilised due to its chosen gauge charge, is split into two pseudo-Dirac mass eigenstates due to Majorana mass term induced by singlet scalar which also takes part in generating right handed neutrino masses responsible for type I seesaw origin of light neutrino masses. The inelastic down scattering of heavier DM component can give rise to the XENON1T excess for keV scale mass splitting with lighter DM component. We fit our model with XENON1T data and also find the final parameter space by using bounds from $(g-2{)}_{\mu }$, DM relic, lifetime of heavier DM, inelastic DM-electron scattering rate, neutrino trident production rate as well as other flavour physics, astrophysical and cosmological observations. A tiny parameter space consistent with all these bounds and requirements will face further scrutiny in near future experiments operating at different frontiers.

   hep-phastro-ph.COhep-exPLB(2020)·44 citations
7. 07*

   The QCD Static Energy using Optimal Renormalization and Asymptotic Padé-approximant Methods

   B. Ananthanarayan🇮🇳 · Diganta Das🇮🇳 · M. S. A. Alam Khan🇮🇳

   The perturbative QCD static potential and ultrasoft contributions, which together give the static energy, have been calculated to three- and four-loop order respectively, by several authors. Using the renormalization group, and Padé approximants, we estimate the four-loop corrections to the static energy. We also employ the optimal renormalization method and resum the logarithms of the perturbative series in order to reduce sensitivity to the renormalization scale in momentum space. This is the first application of the method to results at these orders. The convergence behaviour of the perturbative series is also improved in position space using the Restricted Fourier Transform scheme. Using optimal renormalization, we have extracted the value of ${\Lambda }_{\text{QCD}}^{\overline{\text{MS}}}$ at different scales for two active flavours by matching to the static energy from lattice QCD simulations.

   hep-phhep-lathep-thPRD(2020)·18 citations
8. 08*

   Dark Matter interactions in an $S_4\times Z_5$ flavor symmetry framework

   Giorgio Arcadi🇮🇹 · Davide Meloni🇮🇹 · Martin B. Krauss🇸🇪

   The interactions of dark matter (DM) with the visible sector are often phenomenologically described in the framework of simplified models where the couplings of quarks to the new particles are generally assumed to be universal or have a simple structure motivated by observational benchmarks. They should, however, a priori be treated as free parameters. In this work we discuss one particular realization of the structure of DM couplings based on an $S_4\times Z_5$ flavor symmetry, which has been shown to account reasonably well for fermion masses and mixing, and compare their effect on observational signals to universal as well as Yukawa-like couplings, which are motivated by minimal flavor violation. We will also comment on how these structures could be constrained in UV complete theories of DM and how DM observables, such as, e.g., relic density and direct detection, can potentially be used as a smoking gun for the underlying flavor symmetries.

   hep-phPRD(2020)·4 citations
9. 09*

   A Composite Higgs with a Heavy Composite Axion

   Tony Gherghetta🇺🇸 · Minh D. Nguyen🇺🇸

   We consider the strong dynamics associated with a composite Higgs model that simultaneously produces dynamical axions and solves the strong CP problem. The strong dynamics arises from a new $Sp$ or $SU(4)$ hypercolor gauge group containing QCD colored hyperfermions that confines at a high scale. The hypercolor global symmetry is weakly gauged by the Standard Model electroweak gauge group and an enlarged color group, $SU(N+3)\times SU(N{)}^{\prime }$. When hyperfermion condensates form, they not only lead to an $SU(5)/SO(5)$ composite Higgs model but also spontaneously break the enlarged color group to $SU(3{)}_c\times SU(N{)}_D$. At lower energies, the $SU(N{)}_D$ group confines, producing two dynamical axions that eliminates all CP violation. Furthermore, small instantons from the $SU(N{)}^{\prime }$ group can enhance the axion mass, giving rise to TeV scale axion masses that can be detected at collider experiments. Our model provides a way to unify the composite Higgs with dynamical axions, without introducing new elementary scalar fields, while also extending the range of axion masses that addresses the strong CP problem.

   hep-phJHEP(2020)·79 citations
10. 10*

    Fluid equations for fast-moving electroweak bubble walls

    Benoit Laurent🇨🇦 · James M. Cline🇨🇦

    The cosmological electroweak phase transition can be strongly first order in extended particle physics models. To accurately predict the speed and shape of the bubble walls during such a transition, Boltzmann equations for the CP-even fluid perturbations must be solved. We point out that the equations usually adopted lead to unphysical behavior of the perturbations, for walls traveling close to or above the speed of sound in the plasma. This is an artifact that can be overcome by more carefully truncating the full Boltzmann equation. We present an improved set of fluid equations, suitable for studying the dynamics of both subsonic and supersonic walls, of interest for gravitational wave production and electroweak baryogenesis.

    hep-phastro-ph.COPRD(2020)·93 citations
11. 11*

    Model-independent determination of the Migdal effect via photoabsorption

    C.-P. Liu🇹🇼 · Chih-Pan Wu🇨🇦 · Hsin-Chang Chi🇹🇼 · Jiunn-Wei Chen🇹🇼

    The Migdal effect in a dark-matter-nucleus scattering extends the direct search experiments to the sub-GeV mass region through electron ionization with sub-keV detection thresholds. In this paper, we derive a rigorous and model-independent "Migdal-photoabsorption" relation that links the sub-keV Migdal process to photoabsorption. This relation is free of theoretical uncertainties as it only requires the photoabsorption cross section as the experimental input. Validity of this relation is explicitly checked in the case of xenon with an state-of-the-arts atomic calculation that is well-benchmarked by experiments. The predictions based on this relation for xenon, argon, semiconductor silicon and germanium detectors are presented and discussed.

    hep-phhep-exPRD(2020)·55 citations
12. 12*

    Multi-component Dark Matter in a Simplified E${}_6$SSM Model

    Shaaban Khalil🇪🇬 · Stefano Moretti🇬🇧 · Diana Rojas-Ciofalo🇬🇧 · Harri Waltari🇬🇧

    We study Dark Matter (DM) in the Exceptional Supersymmetric Standard Model (E${}_6$SSM). The model has both active and inert Higgs superfields and by imposing discrete symmetries one can generate two DM candidates. We show that the lightest higgsinos of the active and inert sectors give a viable setup for two-component DM. We also illustrate the scope of both direct and indirect detection experiments in extracting such a DM sector. Future experiments of the former kind have a good chance of finding the active component while the inert higgsino will be very hard to detect while those of the latter kind will have no sensitivity to either candidate.

    hep-phPRD(2020)·23 citations
13. 13*

    A heatwave affair: mixed Higgs-$R^2$ preheating on the lattice

    Fedor Bezrukov🇬🇧 · Chris Shepherd🇬🇧

    We use lattice methods to perform the first nonlinear study of preheating in $R^2$-healed Higgs inflation for "$R^2$-like" parameters $1.1\times 10^9$ and $1.8\times 10^9$ where the curvature-squared coupling $\beta$ and nonminimal coupling $\xi$ of the Higgs field contribute similarly to the CMB scalar perturbations. Preheating occurs first through tachyonic production of Higgs bosons, and later scattering off the homogeneous inflaton field. We generalise our results to "Higgs-like" parameters with smaller $\beta$, where observables saturate the bound of instantaneous preheating. All predictions for the spectral index and tensor-to-scalar ratio lie within the $1\sigma$ region of measurements by the Planck satellite, but a future ground-based experiment optimised for 21 cm tomography may be able to discriminate the mixed Higgs-curvature inflation from the pure Higgs and $R^2$ theories.

    hep-phJCAP(2020)·28 citations
14. 14*

    Heavy meson tomography of cold nuclear matter at the electron-ion collider

    Hai Tao Li🇺🇸 · Ze Long Liu🇺🇸 · Ivan Vitev🇺🇸

    An important part of the physics program at the future electron-ion collider is to understand the nature of hadronization and the transport of energy and matter in large nuclei. Open heavy flavor production in deep inelastic scattering provides a new tool to address these critical questions. We present the first calculation of D-mesons and B-meson cross sections in electron-nucleus collisions at the EIC by including both next-to-leading order QCD corrections and cold nuclear matter effects. Our formalism employs generalized DGLAP evolution to include the contribution of in-medium parton showers, and is based on methods developed in soft-collinear effective theory with Glauber gluons that describe inclusive hadron production in reactions with nucleons and nuclei. The comprehensive study summarized here allows us to identify the optimal observables, center-of-mass energies, and kinematic regions most sensitive to the physics of energy loss and hadronization at the EIC.

    hep-phhep-exnucl-thPLB(2021)·40 citations
15. 15*

    $(g-2)$ anomalies and neutrino mass

    Carolina Arbeláez🇨🇱 · Ricardo Cepedello🇪🇸 · Renato M. Fonseca🇨🇿 · Martin Hirsch🇪🇸

    Motivated by the experimentally observed deviations from standard model predictions, we calculate the anomalous magnetic moments $a_{\alpha }=(g-2{)}_{\alpha }$ for $\alpha =e,\mu$ in a neutrino mass model originally proposed by Babu-Nandi-Tavartkiladze (BNT). We discuss two variants of the model, the original model plus a minimally extended version with an additional hypercharge zero triplet scalar. While the original BNT model can explain $a_{\mu }$, only the variant with the triplet scalar can explain both experimental anomalies. The heavy fermions of the model can be produced at the high-luminosity LHC and in the part of parameter space, where the model explains the experimental anomalies, it predicts certain specific decay patterns for the exotic fermions.

    hep-phPRD(2020)·40 citations
16. 16*

    $\nu$ Electroweak Baryogenesis

    E. Fernandez-Martinez🇪🇸 · J. Lopez-Pavon🇪🇸 · T. Ota🇪🇸 · S. Rosauro-Alcaraz🇪🇸

    We investigate if the CP violation necessary for successful electroweak baryogenesis may be sourced by the neutrino Yukawa couplings. In particular, we consider an electroweak scale Seesaw realization with sizable Yukawas where the new neutrino singlets form (pseudo)-Dirac pairs, as in the linear or inverse Seesaw variants. We find that the baryon asymmetry obtained strongly depends on how the neutrino masses vary within the bubble walls. Moreover, we also find that flavour effects critically impact the final asymmetry obtained and that, taking them into account, the observed value may be obtained in some regions of the parameter space. This source of CP violation naturally avoids the strong constraints from electric dipole moments and links the origin of the baryon asymmetry of the Universe with the mechanism underlying neutrino masses. Interestingly, the mixing of the active and heavy neutrinos needs to be sizable and could be probed at the LHC or future collider experiments.

    hep-phJHEP(2020)·9 citations
17. 17*

    Towards Higgs masses and decay widths satisfying the symmetries in the (N)MSSM

    Florian Domingo🇩🇪 · Sebastian Paßehr🇩🇪

    In models with an extended Higgs sector, such as the (N)MSSM, scalar states mix with one another. Yet, the concept of Higgs mixing is problematic at the radiative level, since it introduces both a scheme and a gauge dependence. In particular, the definition of Higgs masses and decay amplitudes can be impaired by the presence of gauge-violating pieces of higher order. We discuss in depth the origin and magnitude of such effects and suggest two strategies preserving or restoring gauge invariance. In addition, the intuitive concept of mixing and the simplicity of its definition in terms of two-point diagrams can make it tempting to include higher-order corrections on this side of the calculation, irrespectively of the order achieved in vertex diagrams. Using the global $SU(2{)}_{\mathrm{L}}$-symmetry in the decoupling limit, we show that no improvement can be expected from such an approach at the level of the Higgs decays, but that, on the contrary, the higher-order terms may lead to numerically large spurious effects.

    hep-phEPJC(2020)·18 citations
18. 18*

    Modeling the diffusive dynamics of critical fluctuations near the QCD critical point

    Marlene Nahrgang (SUBATECH, Nantes)🇫🇷 · Marcus Bluhm (SUBATECH, Nantes)🇫🇷

    The experimental search for the QCD critical point by means of relativistic heavy-ion collisions necessitates the development of dynamical models of fluctuations. In this work we study the fluctuations of the net-baryon density near the critical point. Due to net-baryon number conservation the correct dynamics is given by the fluid dynamical diffusion equation, which we extend by a white noise stochastic term to include intrinsic fluctuations. We quantify finite resolution and finite size effects by comparing our numerical results to analytic expectations for the structure factor and the equal-time correlation function. In small systems the net-baryon number conservation turns out to be quantitatively and qualitatively important, as it introduces anticorrelations at larger distances. Including nonlinear coupling terms in the form of a Ginzburg-Landau free energy functional we observe non-Gaussian fluctuations quantified by the excess kurtosis. We study the dynamical properties of the system close to equilibrium, for a sudden quench in temperature and a Hubble-like temperature evolution. In the real-time dynamical systems we find the important dynamical effects of critical slowing down, weakening of the extremal value and retardation of the fluctuation signal. In this work we establish a set of general tests, which should be met by any model propagating fluctuations, including upcoming $3+1$ dimensional fluctuating fluid dynamics.

    ↳ nucl-thhep-phPRD(2020)·44 citations
19. 19*

    Statistics for dark matter subhalo searches in gamma rays from a kinematically constrained population model: Fermi-LAT-like telescopes

    Gaétan Facchinetti🇫🇷 · Julien Lavalle🇫🇷 · Martin Stref🇫🇷

    Cold dark matter subhalos are expected to populate galaxies in numbers. If dark matter self-annihilates, these objects turn into prime targets for indirect searches, in particular with gamma-ray telescopes. Incidentally, the Fermi-LAT catalog already contains many unidentified sources that might be associated with subhalos. In this paper, we determine the probability for subhalos to be identified as gamma-ray pointlike sources from their predicted distribution properties. We use a semi-analytical model for the Galactic subhalo population, which, in contrast to cosmological simulations, can be made fully consistent with current kinematic constraints in the Milky Way and has no resolution limit. The model incorporates tidal stripping effects from a realistic distribution of baryons in the Milky Way. The same baryonic distribution contributes a diffuse gamma-ray foreground which adds up to that, often neglected in subhalo searches, generated by the smooth dark matter and the unresolved subhalos. This configuration implies a correlation between pointlike subhalo signals and diffuse background. Based on this semi-analytical modeling, we generate mock gamma-ray data assuming an idealized telescope resembling Fermi-LAT and perform a likelihood analysis to estimate the current and future sensitivity to subhalos in the relevant parameter space. We find a number of detectable subhalos of order $\mathcal{O}(<1)$ for optimistic model parameters and a WIMP mass of 100~GeV, maximized for a cored host halo. This barely provides support to the current interpretation of several Fermi unidentified sources as subhalos. We also find it more likely to detect the smooth Galactic halo itself before subhalos, should dark matter in the GeV-TeV mass range self-annihilate through $s$-wave processes.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phPRD(2022)·14 citations
20. 20*

    Implications of triangular features in the Gaia skymap for the Caustic Ring Model of the Milky Way halo

    Sankha S. Chakrabarty🇺🇸 · Yaqi Han🇺🇸 · Anthony H. Gonzalez🇺🇸 · Pierre Sikivie🇺🇸

    The Gaia map of the Milky Way reveals a pair of triangular features at nearly symmetric locations on opposite sides of the Galactic Center. In this paper we explore the implications of these features assuming they are manifestations of a caustic ring in the dark matter distribution of the Milky Way halo. The existence of a series of such rings is predicted by the Caustic Ring Model. The model's phase-space distribution is that acquired by a rethermalizing Bose-Einstein condensate of axions or axion-like particles. We show that dust is gravitationally entrained by cold axion flows and propose this as an explanation for the sharpness of the triangular features. The locations of the features imply that we on Earth are much closer to the fifth caustic ring than thought on the basis of pre-Gaia observations. Most likely we are inside its tricusp cross-section. In that case the dark matter density on Earth is dominated by four cold flows, termed Big, Little, Up and Down. If we are outside the tricusp cross-section the dark matter density on Earth is dominated by two cold flows, Big and Little. We use the triangular features in the Gaia map, and a matching feature in the IRAS map, to estimate the velocity vectors and densities of the four locally dominant flows.

    ↳ astro-ph.GAhep-phPhys.Dark Univ.(2021)·20 citations
21. 21*

    Massive neutron stars with holographic multiquark cores

    Sitthichai Pinkanjanarod🇹🇭 · Piyabut Burikham🇹🇭

    Phases of nuclear matter are crucial in the determination of physical properties of neutron stars~(NS). In the core of NS, the density and pressure become so large that the nuclear matter possibly undergoes phase transition into a deconfined phase, consisting of quarks and gluons and their colour bound states. Even though the quark-gluon plasma has been observed in ultra-relativistic heavy-ion collisions\cite{Gyulassy, Andronic}, it is still unclear whether exotic quark matter exists inside neutron stars. Recent results from the combination of various perturbative theoretical calculations with astronomical observations\cite{Demorest, Antoniadis} shows that (exotic) quark matter could exist inside the cores of neutron stars above 2.0 solar masses ($M_{\odot }$)~\cite{Annala:2019puf}. We revisit the holographic model in Ref.~\cite{bch, bhp} and implement the equation of states~(EoS) of multiquark nuclear matter to interpolate the pQCD EoS in the high-density region with the nuclear EoS known at low densities. For sufficiently large energy density scale~(${ϵ}_s$) of the model, it is found that multiquark phase is thermodynamically prefered than the stiff nuclear matter above the transition points. The NS with holographic multiquark core could have masses in the range $1.96-2.23(1.64-2.10)M_{\odot }$ and radii $14.3-11.8(14.0-11.1)$ km for ${ϵ}_s=26(28)$ GeV/fm${}^3$ respectively. Effects of proton-baryon fractions are studied for certain type of baryonic EoS; larger proton fractions could reduce radius of the NS with multiquark core by less than a kilometer.

    ↳ nucl-thastro-ph.HEgr-qchep-phEPJC(2021)·23 citations
22. 22*

    Gravitational waves induced by the local-type non-Gaussian curvature perturbations

    Chen Yuan🇨🇳 · Qing-Guo Huang🇨🇳

    The current observational constraints still leave a substantial mass window $\sim [10^{-16},10^{-14}]\cup [10^{-13},10^{-12}]M_{\odot }$ for primordial black holes (PBHs) representing all of dark matter (DM) in our Universe. The gravitational waves (GWs) induced by the curvature perturbations are inevitably generated during the formation of these PBHs, and fall in the frequency band of LISA. Such scalar induced gravitational waves (SIGWs) are supposed to be definitely detected by LISA even when the second-order local-type non-Gaussianity characterized by the parameter $F_{\mathrm{NL}}$ is taken into account. In this letter, we give a comprehensive analysis of the GWs induced by the local-type non-Gaussian curvature perturbations up to the third-order denoted by the non-linear parameter $G_{\mathrm{NL}}$, and find that a log-dependent slope of SIGWs in the infrared region is generically predicted and the amplitude of SIGWs can be further suppressed by several orders of magnitude. Therefore, the null-detection of SIGWs by LISA cannot rule out the possibility of PBHs making up all of DM.

    ↳ astro-ph.COgr-qchep-phhep-thPLB(2021)·99 citations
23. 23*

    Primordial Black Holes as a dark matter candidate

    Anne M. Green🇬🇧 · Bradley J. Kavanagh🇪🇸

    The detection of gravitational waves from mergers of tens of Solar mass black hole binaries has led to a surge in interest in Primordial Black Holes (PBHs) as a dark matter candidate. We aim to provide a (relatively) concise overview of the status of PBHs as a dark matter candidate, circa Summer 2020. First we review the formation of PBHs in the early Universe, focusing mainly on PBHs formed via the collapse of large density perturbations generated by inflation. Then we review the various current and future constraints on the present day abundance of PBHs. We conclude with a discussion of the key open questions in this field.

    ↳ astro-ph.COhep-phJ.Phys.G(2021)·948 citations
24. 24*

    Observational constraints on $\alpha$-attractor inflationary models with a Higgs-like potential

    J. G. Rodrigues🇧🇷 · S. Santos da Costa🇧🇷 · J. S. Alcaniz🇧🇷

    We investigate the observational viability of a class of $\alpha$-attractors inflationary models in light of the most recent Cosmic Microwave Background (CMB) and Large-Scale Structure (LSS) data. By considering a double-well potential we perform a slow-roll analysis to study the behavior of this class of models, which is a continuous interpolation between the chaotic inflation for large values of $\alpha$ and the universal attractor, i.e., $n_s=1-2/N$ and $r=\alpha 12/N^2$ for small $\alpha$, where $n_s$ is the scalar spectral index, $r$ is the tensor-to-scalar ratio, and $N$ is the e-fold number. In order to explore the parameter space of the model, we also perform a MCMC analysis and find $\alpha =7.56\pm 5.15$ ($1\sigma$).

    ↳ astro-ph.COgr-qchep-phPLB(2021)·25 citations
25. 25*

    Visualizing resonances in finite volume

    Peng Guo🇺🇸 · Bingwei Long🇨🇳

    In present work, we explore and experiment an alternative approach of studying resonance properties in finite volume. By analytic continuing finite lattice size $L$ into complex plane, the oscillating behavior of finite volume Green's function is mapped into infinite volume Green's function corrected by exponentially decaying finite volume effect. The analytic continuation technique thus can be applied to study resonance properties directly in finite volume dynamical equations.

    ↳ hep-lathep-phPRD(2020)·22 citations
26. 26*

    A finite box as a tool to distinguish free quarks from confinement at high temperatures

    L. Ya. Glozman🇦🇹 · C. B. Lang🇦🇹

    Above the pseudocritical temperature T_c of chiral symmetry restoration a chiral spin symmetry (a symmetry of the color charge and of electric confinement) emerges in QCD. This implies that QCD is in a confining mode and there are no free quarks. At the same time correlators of operators constrained by a conserved current behave as if quarks were free. This explains observed fluctuations of conserved charges and the absence of the rho-like structures seen via dileptons. An independent evidence that one is in a confining mode is very welcome. Here we suggest a new tool how to distinguish free quarks from a confining mode. If we put the system into a finite box, then if the quarks are free one necessarily obtains a remarkable diffractive pattern in the propagator of a conserved current. This pattern is clearly seen in a lattice calculation in a finite box and it vanishes in the infinite volume limit as well as in the continuum. In contrast, the full QCD calculations in a finite box show the absence of the diffractive pattern implying that the quarks are confined.

    ↳ hep-lathep-phhep-thnucl-thEPJA(2021)·3 citations
27. 27*

    Subluminal stochastic gravitational waves in pulsar-timing arrays and astrometry

    Wenzer Qin🇺🇸 · Kimberly K. Boddy🇺🇸 · Marc Kamionkowski🇺🇸

    The detection of a stochastic background of low-frequency gravitational waves by pulsar-timing and astrometric surveys will enable tests of gravitational theories beyond general relativity. These theories generally permit gravitational waves with non-Einsteinian polarization modes, which may propagate slower than the speed of light. We use the total-angular-momentum wave formalism to derive the angular correlation patterns of observables relevant for pulsar timing arrays and astrometry that arise from a background of subluminal gravitational waves with scalar, vector, or tensor polarizations. We find that the pulsar timing observables for the scalar longitudinal mode, which diverge with source distance in the luminal limit, are finite in the subluminal case. Furthermore, we apply our results to $f(R)$ gravity, which contains a massive scalar degree of freedom in addition to the standard transverse-traceless modes. The scalar mode in this $f(R)$ theory is a linear combination of the scalar-longitudinal and scalar-transverse modes, exciting only the monopole and dipole for pulsar timing arrays and only the dipole for astrometric surveys.

    ↳ gr-qcastro-ph.GAhep-phPRD(2021)·52 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.