Wed·Apr 22, 2020Wednesday·April 22, 2020

1. 01*

   Subleading EW corrections and spin-correlation effects in $t\bar{t}W$ multi-lepton signatures

   Rikkert Frederix🇸🇪 · Ioannis Tsinikos🇸🇪

   Recently a slight tension between data and predictions has been reported in $t\bar{t}W$ production by both the CMS and ATLAS collaborations. We revisit the theoretical predictions for this process, focussing on the following two effects. We disentangle various effects that lead to asymmetries among the leptonic decay products of the (anti-)top quarks and $W$ bosons, for which we find that the spin correlations in the top-quark pair are the dominant source. We also discuss the impact of the large, formally subleading, electroweak corrections to $t\bar{t}W$ production at the LHC. We find that this effect changes the $t\bar{t}W$ cross section significantly in the signature phase-space regions, and should therefore be included differentially in the theory to data comparisons.

   hep-phEPJC(2020)·60 citations
2. 02*

   Reconciling the X(2240) with the Y(2175)

   Dian-Yong Chen🇨🇳 · Jing Liu🇨🇳 · Jun He🇨🇳

   In the present work, we reanalyzed the cross sections for $e^{+}{e}^{-}\to K^{+}{K}^{-}$, where a new structure $X(2240)$ was reported by BES III Collaboration. By including the interference between the direct coupling and vector meson intermediate processes, we find the mass and width of $X(2240)$ are $2197.4\pm 4.4$ MeV and $75.6\pm 7.2$ MeV, respectively, which are well consistent with the PDG average values of the resonance parameters for $Y(2175)$, thus, we conclude that the $X(2240)$ should be the same state as the $Y(2175)$.

   hep-phPRD(2020)·12 citations
3. 03*

   Quadruply charmed baryons as heavy quark symmetry partners of the $D_{s0}^{\ast }(2317)$

   Tian-Wei Wu🇨🇳 · Ming-Zhu Liu🇨🇳 · Li-Sheng Geng🇨🇳 · Emiko Hiyama🇯🇵 · Manuel Pavon Valderrama🇨🇳 · Wen-Ling Wang🇨🇳

   Both unitary chiral theories and lattice QCD simulations show that the $DK$ interaction is attractive and can form a bound state, namely, $D_{s0}^{\ast }(2317)$. Assuming the validity of the heavy antiquark-diquark symmetry (HADS), the ${\Xi }_{cc}\bar{K}$ interaction is the same as the $DK$ interaction, which implies the existence of a ${\Xi }_{cc}\bar{K}$ bound state with a binding energy of $49-64$ MeV. In this work, we study whether a ${\Xi }_{cc}{\Xi }_{cc}\bar{K}$ three-body system binds. The ${\Xi }_{cc}{\Xi }_{cc}$ interaction is described by exchanging $\pi$, $\sigma$, $\rho$, and $\omega$ mesons, with the corresponding couplings related to those of the $NN$ interaction via the quark model. We indeed find a ${\Xi }_{cc}{\Xi }_{cc}\bar{K}$ bound state, with quantum numbers $J^P=0^{-}$, $I=\frac{1}{2}$, $S=1$ and $C=4$, and a binding energy of $80-118$ MeV. It is interesting to note that this system is very similar to the well-known $NN\bar{K}$ system, which has been studied extensively both theoretically and experimentally. Within the same framework, we show the existence of a $NN\bar{K}$ state with a binding energy of $35-43$ MeV, consistent with the results of other theoretical works and experimental data, which serves as a consistency check on the predicted ${\Xi }_{cc}{\Xi }_{cc}\bar{K}$ bound state.

   hep-phhep-latnucl-thEPJC(2020)·14 citations
4. 04*

   Extraction of $ND$ scattering lengths from the ${\Lambda }_b\to {\pi }^{-}p{D}^0$ decay and properties of the ${\Sigma }_c(2800{)}^{+}$

   Shuntaro Sakai🇨🇳 · Feng-Kun Guo🇨🇳 · Bastian Kubis🇩🇪

   The isovector and isoscalar $ND$ $s$-wave scattering lengths are extracted by fitting to the LHCb data of the $p{D}^0$ invariant-mass distribution in the decay ${\Lambda }_b\to {\pi }^{-}p{D}^0$, making use of the cusp effect at the $n{D}^{+}$ threshold. The analysis is based on a coupled-channel nonrelativistic effective field theory. We find that the real part of the isovector $ND$ scattering length is unnaturally large due to the existence of a near-threshold state with a mass around 2.8 GeV. The state is consistent with the ${\Sigma }_c(2800{)}^{+}$ resonance observed at Belle. Our results suggest that it couples strongly to the $ND$ channel in an $s$-wave, and that its quantum numbers are $J^P=1/2^{-}$. The strong cusp behavior at the $n{D}^{+}$ threshold can be verified using updated LHCb data.

   hep-phhep-exnucl-thPLB(2020)·21 citations
5. 05*

   Future lepton collider prospects for a ubiquitous composite pseudo-scalar

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

   Composite Higgs models feature new strong dynamics leading to the description of the Higgs boson as a bound state arising from the breaking of a global (flavour) symmetry. These models generally include light states generated by the same dynamics, the detection of which may present the first observable signs of compositeness. One such state is a pseudo-scalar boson resulting from the breaking of a $U(1)$ symmetry common to most composite setups, and whose hints are expected to be visible through low-mass resonance searches at present and future hadron and lepton colliders. In this work we study the phenomenology of this pseudo-scalar field. We show that, for a light state, bottom quark loop effects dominantly impact the production cross section and considerably modify the decay pattern. Moreover, we make a case for targeted low-mass analyses at future lepton colliders, with an emphasis on high-luminosity machines aiming to operate at low centre-of-mass energies. We present a simplified outline of a search for this light pseudo-scalar at one such machine, considering electron-positron collisions at the $Z$-pole. We focus on a signature arising from the pseudo-scalar decay into a pair of hadronic taus and a production mode association with a pair of leptons of opposite electric charges, and compare cut and count methods with machine learning methods.

   hep-phPRD(2020)·12 citations
6. 06*

   Chiral transition and the chiral charge density of the hot and dense QCD matter

   Chao Shi🇨🇳 · Xiao-Tao He🇨🇳 · Wen-Bao Jia🇨🇳 · Qing-Wu Wang🇨🇳 · Shu-Sheng Xu🇨🇳 · Hong-Shi Zong🇨🇳

   We study the chirally imbalanced hot and dense strongly interacting matter by means of the Dyson-Schwinger equations (DSEs). The chiral phase diagram is studied in the presence of chiral chemical potential ${\mu }_5$. The chiral quark condensate $⟨\bar{\psi }\psi ⟩$ is obtained with the Cornwall-Jackiw-Tomboulis (CJT) effective action in concert with the Rainbow truncation. Catalysis effect of dynamical chiral symmetry breaking (DCSB) by ${\mu }_5$ is observed. We examine with two popular gluon models and consistency is found within the DSE approach, as well as in comparison with lattice QCD. The CEP location $({\mu }_E,T_E)$ shifts toward larger $T_E$ but constant ${\mu }_E$ as ${\mu }_5$ increases. A technique is then introduced to compute the chiral charge density $n_5$ from the fully dressed quark propagator. We find the $n_5$ generally increases with temperature $T$, quark number chemical potential $\mu$ and ${\mu }_5$. Since the chiral magnetic effect (CME) is typically investigated with peripheral collisions, we also investigate the finite size effect on $n_5$ and find an increase in $n_5$ with smaller system size.

   hep-phJHEP(2020)·24 citations
7. 07*

   A proposal to the '$\frac{1}{2}$ vs. $\frac{3}{2}$ puzzle'

   Qiang Li🇨🇳 · Wei Feng🇨🇳 · Guo-Li Wang🇨🇳

   We reconsider the semileptonic decays of $B\to D_1^{(\prime )}l{\bar{\nu }}_l$. The previous theoretical calculations predict a significantly smaller rate for the semileptonic decay of $B$ to $D_1^{\prime }(J_l=\frac{1}{2})$ compared with that to the $D_1(J_l=\frac{3}{2})$, which is not consistent with the current experimental data. This conflict is the so-called `$\frac{1}{2}$ vs. $\frac{3}{2}$ puzzle'. In this work, we propose a simple scheme to fix this problem, where we suppose that the strong eigenstates $D_1^{(\prime )}$ do not coincide with the eigenstate of the weak interaction, since no experimental results show the weak and the strong interactions have to share the same eigenstates. Within the framework of this tentative scheme, meson $B$ first weakly decays to {the weak eigenstates} $D_{\alpha (\beta )}$ and then the latter are detected as the $D_1^{(\prime )}$ by the strong products $D^{\ast }\pi$. We predict that there exist two new particles $D_{\alpha (\beta )}$ with $J^P=1^{+}$ which were not previously identified. The good performance of the new scheme in describing the experimental data may hint at new symmetry in the weak decays of $B_q$ to $1^{+}$ heavy-light mesons. To test the scheme proposed here, we suggest an experiment to detect the difference in the invariant mass spectra of $D_1$ reconstructed from the $B$ weak decay and from the strong decay products.

   hep-phSymmetry(2023)·1 citation
8. 08*

   Study of some (non-)conventional mesons in the framework of effective models

   Milena Piotrowska🇵🇱

   The main aim of our study is to understand the nature of some conventional and non-conventional mesonic states by applying effective QFT models. We start from the relativistic Lagrangians containing a unique $q\bar{q}$ seed state which is strongly coupled to the low-masses decay products of the original state. We find out that some states may appear as a dynamically generated companion poles of the heavier $q\bar{q}$ mesons. In particular we show that $K_0^{\ast }(700)$ is a companion pole of the well-known $K_0^{\ast }(1430)$ resonance, $X(3872)$ emerges as a (virtual) companion pole of ${\chi }_{c1}(2P)$, and the puzzling $Y(4008)$ is not a real state, but a spurious enhancement which appears when studying the state $\psi (4040)$.

   hep-phActa Phys.Polon.Supp.(2021)·1 citation
9. 09*

   Constraint on Vector Coherent Oscillation Dark Matter with Kinetic Function

   Kazunori Nakayama🇯🇵

   A spatially uniform vector condensate can be formed during inflation if the vector boson is coupled to the inflaton through nontrivial kinetic function. The coherent oscillation of such a massive vector boson is a dark matter candidate. In this paper we consider the case where the vector boson energy density increases during inflation and show that the curvature/isocurvature perturbation gives stringent constraint on this scenario.

   hep-phastro-ph.COJCAP(2020)·49 citations
10. 10*

    The effect of the early kinetic decoupling in a fermionic dark matter model

    Tomohiro Abe🇯🇵

    We study the effect of the early kinetic decoupling in a model of fermionic dark matter (DM) that interacts with the standard model particles only by exchanging the Higgs boson. There are two DM-Higgs couplings, namely CP-conserving and CP-violating couplings. If the mass of the DM is slightly below half of the Higgs boson mass, then the couplings are suppressed to obtain the measured value of the DM energy density by the freeze-out mechanism. In addition, the scattering processes of DM off particles in the thermal bath are suppressed by the small momentum transfer if the CP-violating DM-Higgs coupling is larger than the CP-conserving one. Due to the suppression, the temperature of the DM can differ from the temperature of the thermal bath. By solving coupled equations for the number density and temperature of the DM, we calculate the DM-Higgs couplings that reproduce the right amount of the DM relic abundance. We find that the couplings have to be larger than the one obtained without taking into account the difference in the temperatures. A consequence of the enhancement of the DM-Higgs couplings is the enhancement of the Higgs invisible decay branching ratio. The enhancement is testable at current and future collider experiments.

    hep-phPRD(2020)·18 citations
11. 11*

    The gravitational waves from the collapsing domain walls in the complex singlet model

    Ning Chen🇨🇳 · Tong Li🇨🇳 · Yongcheng Wu🇨🇦

    We study the CP domain walls and the consequent gravitational waves induced by the spontaneous breaking of the CP symmetry in the complex singlet extension to the Standard Model. We impose the constraints from the unitarity, stability and the global minimal of the vacuum solutions on the model parameter space. The CP domain wall profiles and tensions are obtained by numerically solving the relevant field equations. The explicit CP violation terms are then introduced to the potential as biased terms to make the domain walls unstable and collapse, The BBN bound on the magnitude of the energy bias is taken into account. To achieve sufficiently strong gravitational wave signals, the domain wall tension $\sigma$ is required to be at least $\sigma /{\mathrm{TeV}}^3\sim \mathcal{O}(10^3)$. We find that the gravitational wave spectrum can be probed in the future SKA and/or DECIGO programs, when the typical mass scale is at least $\sim \mathcal{O}(10)$ TeV and the explicit CP violation terms are as small as $\mathcal{O}(10^{-29})-\mathcal{O}(10^{-27})$. The gravitational waves from collapsing domain walls thus provide a complementarity to the probe of extremely small CP violation at high-energy scale.

    hep-phastro-ph.HEgr-qcJHEP(2020)·24 citations
12. 12*

    Bayesian fit analysis to full distribution data of $\bar{B}\to D^{(\ast )}\ell \bar{\nu }$: $|V_{cb}|$ determination and New Physics constraints

    Syuhei Iguro🇯🇵 · Ryoutaro Watanabe🇮🇹

    We investigate the semi-leptonic decays of $\bar{B}\to D^{(\ast )}\ell \bar{\nu }$ in terms of the Heavy-Quark-Effective-Theory (HQET) parameterization for the form factors, which is described with the heavy quark expansion up to $\mathcal{O}(1/m_c^2)$ beyond the simple approximation considered in the original CLN parameterization. An analysis with this setup was first given in the literature, and then we extend it to the comprehensive analyses including (i) simultaneous fit of $|V_{cb}|$ and the HQET parameters to available experimental full distribution data and theory constraints, and (ii) New Physics (NP) contributions of the $V_2$ and $T$ types to the decay distributions and rates. For this purpose, we perform Bayesian fit analyses by using Stan program, a state-of-the-art public platform for statistical computation. Then, we show that our $|V_{cb}|$ fit results for the SM scenarios are close to the PDG combined average from the exclusive mode, and indicate significance of the angular distribution data. In turn, for the $\text{SM}+\text{NP}$ scenarios, our fit analyses find that non-zero NP contribution is favored at the best fit point for both $\text{SM}+V_2$ and $\text{SM}+T$ depending on the HQET parameterization model. A key feature is then realized in the $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$ observables. Our fit result of the HQET parameters in the $\text{SM}(+T)$ produces a consistent value for $R_D$ while smaller for $R_{D^{\ast }}$, compared with the previous SM prediction in the HFLAV report. On the other hand, $\text{SM}+V_2$ points to smaller and larger values for $R_D$ and $R_{D^{\ast }}$ than the SM predictions. In particular, the $R_{D^{\ast }}$ deviation from the experimental measurement becomes smaller, which could be interesting for future improvement on measurements at the Belle II experiment.

    hep-phhep-exJHEP(2020)·101 citations
13. 13*

    Quark-quark-gluon vertex for heavy quarks up to order 1/m^5

    Guojun Huang🇨🇳 · Pengfei Zhuang🇨🇳

    Instead of the often used Foldy-Wouthuysen-Tani (FWT) transformation in non-relativistic quantum chromodynamics (NRQCD), we take a more general relation between the relativistic and non-relativistic on-shell spinors to recalculate the quark-quark-gluon vertex for heavy quarks. In comparison with the previous result using FWT, the recalculated coefficients in the NRQCD Lagrangian are different at order $1/m^3$ and new at order $1/m^4$ and $1/m^5$, where $m$ is the heavy quark mass.

    hep-phhep-thPRD(2020)·2 citations
14. 14*

    Gravity-Matter Feynman Rules for any Valence

    David Prinz🇩🇪

    This article derives and presents the Feynman rules for (effective) Quantum General Relativity coupled to the Standard Model for any vertex valence and with general gauge parameter $\zeta$. The results are worked out for the metric decomposition $g_{\mu \nu }={\eta }_{\mu \nu }+\varkappa h_{\mu \nu }$, a linearized de Donder gauge fixing and four dimensions of spacetime. To this end, we calculate the Feynman rules for gravitons, graviton-ghosts and for the couplings of gravitons to scalars, spinors, gauge bosons and gauge ghosts.

    ↳ hep-thgr-qchep-phClass.Quant.Grav.(2021)·31 citations
15. 15*

    Toward a unified equation of state for multi-messenger astronomy

    Michał Marczenko🇵🇱 · David Blaschke🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

    We present a first step in developing a benchmark equation-of-state (EoS) model for multi-messenger astronomy that unifies the thermodynamics of quark and hadronic degrees of freedom. A Lagrangian approach to the thermodynamic potential of quark-meson-nucleon (QMN) matter was used. In this approach, dynamical chiral-symmetry breaking is described by the scalar mean-field dynamics coupled to quarks and nucleons and their chiral partners, whereby its restoration occurs in the hadronic phase by parity doubling, as well as in the quark phase. Quark confinement was achieved by an auxiliary scalar field that parametrizes a dynamical infrared cutoff in the quark sector, serving as an ultraviolet cutoff for the nucleonic phase space. The gap equations were solved for the isospin-symmetric case, as well as for neutron star (NS) conditions. We also calculated the mass-radius (MR) relation of NSs and their tidal deformability parameter. The obtained EoS is in accordance with nuclear matter properties at saturation density and with the flow constraint from heavy ion collision experiments. For isospin-asymmetric matter, a sequential occurrence of light quark flavors is obtained, allowing for a mixed phase of chirally-symmetric nucleonic matter with deconfined down quarks. The MR relations and TDs for compact stars fulfill the constraints from the latest astrophysical observations for PSR J0740+6620, PSR J0030+0451, and the NS merger GW170817, whereby the tension between the maximum mass and compactness constraints rather uniquely fixes the model parameters. The model predicts the existence of stars with a core of chirally restored but purely hadronic (confined) matter for masses beyond $1.8M_{\odot }$. Stars with pure-quark matter cores are found to be unstable against the gravitational collapse. This instability is shifted to even higher densities if repulsive interactions between quarks are included.

    ↳ astro-ph.HEhep-phnucl-thAstron.Astrophys.(2020)·49 citations
16. 16*

    On the Symmetries of Cosmological Perturbations

    Daniel Green🇺🇸 · Enrico Pajer🇬🇧

    The space of inflationary models is vast, containing wide varieties of mechanisms, symmetries, and spectra of particles. Consequently, the space of observational signatures is similarly complex. Hence, it is natural to look for boundaries of the space of models and their signatures. In this paper, we explore the possible symmetries associated with the primordial cosmological perturbations and their correlators in the asymptotic future. Assuming the observed homogeneity, isotropy and (approximate) scale invariance, we prove three main results. First, correlation functions of scalar metric fluctuations are uniquely characterized by soft theorems and are free from ambiguity under field redefinitions. Second, whatever the particle content and interactions, when the standard soft theorems apply, invariance under de Sitter boosts (linearly realized conformal invariance) is only possible if all connected correlators vanish identically, i.e. if the theory is free. Third, conformal invariance is the largest set of linearly realized (bosonic) symmetries of the correlators of any single scalar, irrespectively of any soft theorems or particle content.

    ↳ hep-thastro-ph.COhep-phJCAP(2020)·71 citations
17. 17*

    CHY Theory for Several Fields

    C.S. Lam🇨🇦

    The Cachazo-He-Yuan (CHY) formula was originally proposed to describe on-shell scattering of particles from a single massless field. We present a method to modify it to include several interacting scalar fields, all possessing different masses and possibly off-shell momenta. The method is applied to Yukawa interactions between a number of scalar nucleons and pions, and to the ${\text{f}}_1{\text{f}}_2{\text{f}}_3$ coupling of three different scalar fields. Composite models constructed from existing theories can be used to broaden the scope of the method. The modification is applied to describe Compton scattering from a massive particle, and to photon bremsstrahlung. It is also employed to generalize the disk function $Z$ and the sphere function $J$.

    ↳ hep-thhep-phPRD(2020)·3 citations
18. 18*

    Anomaly in decay of 8Be and 4He -- can an observed light boson mediate low energy nucleon-nucleon interactions ?

    M. Veselsky🇨🇿 · V. Petousis🇨🇿 · J. Leja🇸🇰

    We present a hypothesis that the anomaly in the folding angle distribution of electron-positron pairs, emitted in the decay of the excited levels of nucleus ${}^8$Be and ${}^4$He can be related to the cluster structure of the decaying state. Furthermore, we present a hypothesis that the potentially observed boson with re st mass $m_X$=17 MeV can mediate the nucleon-nucleon interaction at the low-energy regime of QCD, in particular in the weakly bound cluster state p+${}^7$Li,${}^3$H. We present a possible equations of state of symmetric nuclear matter corresponding to the vector meson mass $m_v$=17 MeV, obtained using relativistic mean field theory of nuclear force, QHD-I in particular, with physically relevant incompessibility K${}_0$=240-260 MeV and the values of couplings $g_v$, $g_s$ lower than unity. Based on concepts of chiral symmetry breaking, we show that reduction of the rest mass of pseudoscalar particle from physical value $m_{\pi }$=135 MeV to $m_X$=17 MeV is equivalent to reduction of the quark mass from dynamical value around 310 MeV down to current quark mass around 5 MeV ($\frac{m_X^2}{m_{q,curr}}\simeq \frac{m_{\pi }^2}{m_{q,dyn}}$). Corresponding version of Goldberger-Treiman relation leads to the value of coupling close to the results from relativistic mean field theory of nuclear force. Both model approaches thus point towards apparent restoration of chiral symmetry in nucleon-nucleon interaction at large distances, possibly via bounce into false instanton vacuum. Observation of boson with rest mass $m_X$=17 MeV in the decay of high lying excited states of ${}^8$Be and ${}^4$He can possibly resolve one of the longest lasting open questions in nuclear physics.

    ↳ nucl-thhep-phnucl-exJ.Phys.G(2021)·10 citations
19. 19*

    Skewness of mean transverse momentum fluctuations in heavy-ion collisions

    Giuliano Giacalone🇫🇷 · Fernando G. Gardim🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Jean-Yves Ollitrault🇫🇷

    We propose the skewness of mean transverse momentum, $⟨p_t⟩$, fluctuations as a fine probe of hydrodynamic behavior in relativistic nuclear collisions. We describe how the skewness of the $⟨p_t⟩$ distribution can be analyzed experimentally, and we use hydrodynamic simulations to predict its value. We predict in particular that $⟨p_t⟩$ fluctuations have positive skew, which is significantly larger than if particles were emitted independently. We elucidate the origin of this result by deriving generic formulas relating the fluctuations of $⟨p_t⟩$ to the fluctuations of the early-time thermodynamic quantities. We postulate that the large positive skewness of $⟨p_t⟩$ fluctuations is a generic prediction of hydrodynamic models.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2021)·51 citations
20. 20*

    New approach to search for parity-even and parity-odd time-reversal violation beyond the Standard Model in a storage ring

    N.N. Nikolaev🇷🇺 · F. Rathmann🇩🇪 · A.J. Silenko🇷🇺 · Yu. Uzikov🇷🇺

    Time-reversal breaking and parity-conserving millistrong interactions, suggested in 1965, still remain a viable mechanism of CP-violation beyond the Standard Model. One of its possible manifestations is the T-odd asymmetry in the transmission of tensor-polarized deuterons through a vector-polarized hydrogen gas target. Upon the rotation of the deuteron polarization from the vertical direction into the ring plane, the T-odd asymmetries, odd against the reversal of the proton polarization in the target, will continuously oscillate with first or second harmonics of the spin precession frequency. The Fourier analysis of the oscillating T-odd asymmetries allows for an easy separation from background persistent in conventional experiments employing static vector and tensor polarizations.

    ↳ nucl-thhep-exhep-phnucl-ex+1PLB(2020)·19 citations
21. 21*

    Dark Energy, Dark Matter and Baryogenesis from a Model of a Complex Axion Field

    Robert Brandenberger🇨🇦 · Jürg Fröhlich (McGill Univ. and ETH Zurich)🇨🇭

    We introduce and study a model designed to simultaneously shed light on the mysteries connected with Baryogenesis, Dark Matter and Dark Energy. The model describes a self-interacting complex axion field whose imaginary part, a pseudo-scalar axion, couples to the instanton density of gauge fields including the hypermagnetic field. This coupling may give rise to baryogenesis in the early universe. After tracing out the gauge and matter degrees of freedom, a non-trivial effective potential for the angular component of the axion field is obtained. It is proposed that oscillations of this component around a minimum of its effective potential can be interpreted as Dark Matter. The absolute value of the axion field rolls slowly towards $0$. At late times, it can give rise to Dark Energy.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2021)·17 citations
22. 22*

    Area covered by disks in small-bounded continuum percolating systems: An application to the string percolation model

    J. E. Ramírez🇪🇸 · C. Pajares🇪🇸

    In string percolation model, the study of colliding systems at high energies is based on a continuum percolation theory in two dimensions where the number of strings distributed in the surface of interest is strongly determined by the size and the energy of the colliding particles. It is also expected that the surface where the disks are lying be finite, defining a system without periodic boundary conditions. In this work, we report modifications to the fraction of the area covered by disks in continuum percolating systems due to a finite number of disks and bounded by different geometries: circle, ellipse, triangle, square and pentagon, which correspond to the first Fourier modes of the shape fluctuation of the initial state after the particle collision. We find that the deviation of the fraction of area covered by disks from its corresponding value in the thermodynamic limit satisfies a universal behavior, where the free parameters depend on the density profile, number of disks and the shape of the boundary. Consequently, it is also found that the color suppression factor of the string percolation model is modified by a damping function related to the small-bounded effects. Corrections to the temperature and the speed of sound defined in string systems are also shown for small and elliptically bounded systems.

    ↳ cond-mat.stat-mechhep-phPRE(2019)·10 citations
23. 23*

    Linear response theory of relativistic hydrodynamics with spin

    David Montenegro🇧🇷 · Giorgio Torrieri🇧🇷

    We use linear response techniques to develop the previously proposed relativistic ideal fluid limit with a non-negligible spin density. We confirm previous results and obtain expressions for the microscopic transport coefficients using Kubo-like formulae and buld up the effective field theory from the computed correlation functions. We also confirm that polarization makes vortices aquire an effective mass via a mechanism similar to the Anderson-Higgs mechanism in superconductors. As speculated earlier, this could stabilize the ideal hydrodynamic limit against fluctuation-driven vortices

    ↳ hep-thhep-phPRD(2020)·103 citations
24. 24*

    Primordial Intermediate Mass Black Holes as Dark Matter

    Paul H. Frampton🇮🇹

    Among particle theory candidates for the dark matter constituents. axions and WIMPs are the most popular. In this talk we discuss these then focus on our preferred astrophysical candidate, the Primordial Intermediate Mass Black Holes in the acronym $DM=PIMBHs$. The earliest experimental confirmation may come from microlensing of the Magellanic Clouds at the LSST 8m telescope in the mid-2020s, or possibly a few years earlier in 2021 from work being pursued, using DECam data from the smaller Blanco 4m tescope, at LLNL.

    ↳ astro-ph.GAhep-phInt.J.Mod.Phys.A(2020)·3 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.