Thu·May 7, 2020Thursday·May 7, 2020

1. 01*

   Chiral molecules as sensitive probes for direct detection of $\mathcal{P}$-odd cosmic fields

   Konstantin Gaul🇩🇪 · Mikhail G. Kozlov🇷🇺 · Timur A. Isaev🇷🇺 · Robert Berger🇩🇪

   Particular advantages of chiral molecules for direct detection of the time-dependence of pseudoscalar and the timelike-component of pseudovector cosmic fields are highlighted. Such fields are invoked in different models for cold dark matter or in the Lorentz-invariance violating standard model extensions and thus are signatures of physics beyond the standard model. The sensitivity of a twenty year old experiment with the molecule CHBrClF to pseudovector cosmic fields as characterized by the parameter $|b_0^{\mathrm{e}}|$ is estimated to be $\mathcal{O}(10^{-12}\mathrm{GeV})$ and allows to predict the sensitivity of future experiments with favorable choices of chiral molecular probes to be $\mathcal{O}(10^{-17}\mathrm{GeV})$, which will be an improvement of the present best limits by at least two orders of magnitude.

   hep-phphysics.atom-phphysics.chem-phPRL(2020)·27 citations
2. 02*

   Quantum black holes in the horizon quantum mechanics model at the Large Hadron Collider

   Douglas M. Gingrich🇨🇦 · Brennan Undseth🇨🇦

   Quantum black hole production at the Large Hadron Collider is investigated using the horizon quantum mechanics model. This model has novel implications for how black holes might be observed in collider experiments. Black hole production is predicted to be possible below the Planck scale, thus leading to the intriguing possibility that black holes could be produced even if the Planck scale is slightly above the collider centre of mass energy. In addition, the usual anticipated resonance in the black hole mass distribution is significantly widened in this model. For values of the Planck scale above the current lower limits, the shape of the black hole mass distribution is almost independent of the Planck scale and depends more on the number of extra dimensions. These model features suggest the need for alternative search strategies in collider experiments.

   hep-phgr-qchep-exhep-thPRD(2020)·2 citations
3. 03*

   Role of transverse gluon in SSA

   G.P.Zhang🇨🇳

   It is known the single transverse spin asymmetry in semi-inclusive deep inelastic scattering can be factorized by a twist-3 distribution function $T_F$, which contains a gluon field strength tensor. With transverse gluon included in the power expansion, we find the gluon field strength tensor can be recovered definitely in soft-gluon-pole contribution at leading order of ${\alpha }_s$ expansion. This conclusion holds in Feynman and light-cone gauges.

   hep-ph1 citation
4. 04*

   Potential Model for ${\Sigma }_u^{-}$ Hybrid Meson State

   Nosheen Akbar🇵🇰 · Saba Noor🇵🇰

   In this paper, lattice simulations are used to propose a potential model for gluonic excited ${\Sigma }_u^{-}$ states of bottomonium meson . This proposed model is used to calculate radial wave functions, masses and radii of ${\Sigma }_u^{-}$ bottomonium hybrid mesons. Here, gluonic field between a quark and an antiquark is treated as in the Born-Oppenheimer expansion, and Schr$\ddot{o}$dinger equation is numerically solved employing shooting method. Results of calculated masses for ${\Sigma }_u^{-}$ state are in quite good agreement with the lattice simulations.

   hep-phActa Phys.Polon.B(2021)·3 citations
5. 05*

   Description of the newly observed ${\Xi }_c^0$ states as molecular states

   HongQiang Zhu🇨🇳 · NaNa Ma🇨🇳 · Yin Huang🇨🇳

   Very recently, three new structures ${\Xi }_c(2923{)}^0$, $\Xi (2938{)}^0$, and $\Xi (2964{)}^0$ at the invariant mass spectrum of ${\Lambda }_c^{+}{K}^{-}$ observed by the LHCb Collaboration triggers a hot discussion about their inner structure. In this work, we study the strong decay mode of the newly observed ${\Xi }_c$ assuming that the ${\Xi }_c$ is a $\bar{D}\Lambda -\bar{D}\Sigma$ molecular state. With the possible quantum numbers $J^p=1/2^{\pm }$ and $3/2^{\pm }$, the partial decay widths of the $\bar{D}\Lambda -\bar{D}\Sigma$ molecular state into the ${\Lambda }_c^{+}{K}^{-}$, ${\Sigma }_c^{+}{K}^{-}$,and ${\Xi }_c^{+}{\pi }^{-}$ final states through hadronic loop are calculated with the help of the effective Lagrangians. By comparison with the LHCb observation, the current results of total decay width support the $\Xi (2923{)}^0$ as $\bar{D}\Lambda -\bar{D}\Sigma$ molecule while the decay width of the ${\Xi }_c(2938{)}^0$ and $\Xi (2964{)}^0$ can not be well reproduced in the molecular state picture. In addition, the calculated partial decay widths with $S$ wave $\bar{D}\Lambda -\bar{D}\Sigma$ molecular state picture indicate that allowed decay modes, ${\Xi }_c^{+}{\pi }^{-}$, may have the biggest branching ratios for the ${\Xi }_c(2923)$. The experimental measurements for this strong decay process could be a crucial test for the molecule interpretation of the ${\Xi }_c(2923)$.

   hep-phnucl-thEPJC(2020)·18 citations
6. 06*

   Tau decay into ${\nu }_{\tau }$ and $a_1(1260)$, $b_1(1235)$, and two $K_1(1270)$

   L. R. Dai🇨🇳 · L. Roca🇪🇸 · E. Oset🇪🇸

   We study the $\tau \to {\nu }_{\tau }A$ decay, with $A$ an axial-vector meson. We produce the $a_1(1260)$ and $b_1(1235)$ resonances in the Cabibbo favored mode and two $K_1(1270)$ states in the Cabibbo suppressed mode. We take advantage of previous chiral unitary approach results where these resonances appear dynamically from the vector and pseudoscalar meson interaction in s-wave. Actually two different poles were obtained associated to the $K_1(1270)$ quantum numbers. We find that the unmeasured rates for $b_1(1235)$ production are similar to those of the $a_1(1260)$ and for the two $K_1$ states we suggest to separate the present information on the $\bar{K}\pi \pi$ invariant masses into ${\bar{K}}^{\ast }\pi$ and $\rho K$ modes, the channels to which these two resonances couple most strongly, predicting that these modes peak at different energies and have different widths. These measurements should shed light on the existence of these two $K_1$ states.

   hep-phEPJC(2020)·10 citations
7. 07*

   The global geometrical property of jet events in high-energy nuclear collisions

   Shi-Yong Chen🇨🇳 · Wei Dai🇨🇳 · Shan-Liang Zhang🇨🇳 · Qing Zhang🇨🇳 · Ben-Wei Zhang🇨🇳

   We present the first theoretical study of medium modifications of the global geometrical pattern, i.e., transverse sphericity ($S_{\perp }$) distribution of jet events with parton energy loss in relativistic heavy-ion collisions. In our investigation, POWHEG+PYTHIA is employed to make an accurate description of transverse sphericity in the p+p baseline, which combines the next-to-leading order (NLO) pQCD calculations with the matched parton shower (PS). The Linear Boltzmann Transport (LBT) model of the parton energy loss is implemented to simulate the in-medium evolution of jets. We calculate the event normalized transverse sphericity distribution in central Pb+Pb collisions at the LHC, and give its medium modifications. An enhancement of transverse sphericity distribution at small $S_{\perp }$ region but a suppression at large $S_{\perp }$ region are observed in A+A collisions as compared to their p+p references, which indicates that in overall the geometry of jet events in Pb+Pb becomes more pencil-like. We demonstrate that for events with 2 jets in the final-state of heavy-ion collisions, the jet quenching makes the geometry more sphere-like with medium-induced gluon radiation. However, for events with $\ge 3$~jets, parton energy loss in the QCD medium leads to the events more pencil-like due to jet number reduction, where less energetic jets may lose their energies and then fall off the jet selection kinematic cut. These two effects offset each other and in the end result in more jetty events in heavy-ion collisions relative to that in p+p.

   hep-phnucl-exnucl-thEPJC(2020)·9 citations
8. 08*

   Axionlike-particle generation by laser-plasma interaction

   Shan Huang🇨🇳 · Baifei Shen🇨🇳 · Zhigang Bu🇨🇳 · Xiaomei Zhang🇨🇳 · Liangliang Ji🇨🇳 · Shuhua Zhai🇨🇳

   The hypothetical axion and axion-like particles, feebly coupled with photon, have not yet been found in any experiment. With the improvement of laser technique, much stronger but shorter quasi-static electric and magnetic fields can be created in laboratory using laser-plasma interaction, compared to the fields of large magnets, to help the search of axion. In this article, we discuss the feasibility of ALPs exploration using planarly or cylindrically symmetric laser-plasma fields as background and an x-ray free-electron laser as probe. Both the probe and the background fields are polarized such that the existence of ALPs in the corresponding parameter space will cause polarization rotation of the probe, which can be detected with high accuracy. Besides, a structured field in the plasma creates a tunable transverse profile for the interaction and improves the signal-to-noise ratio via phase-matching mechanism. The ALP mass discussed in this article ranges from $10^{-3}$ eV to 1 keV. Some simple schemes and estimations on ALP production and polarization rotation of probe photon are given, which reveals the possibility of future laser-plasma ALP source in laboratory.

   hep-phphysics.opticsphysics.plasm-phPhys.Scripta(2022)·14 citations
9. 09*

   Freeze-in Dirac neutrinogenesis: thermal leptonic CP asymmetry

   Shao-Ping Li🇨🇳 · Xin-Qiang Li🇨🇳 · Xin-Shuai Yan🇨🇳 · Ya-Dong Yang🇨🇳

   We present a freeze-in realization of the Dirac neutrinogenesis in which the decaying particle that generates the lepton-number asymmetry is in thermal equilibrium. As the right-handed Dirac neutrinos are produced non-thermally, the lepton-number asymmetry is accumulated and partially converted to the baryon-number asymmetry via the rapid sphaleron transitions. The necessary CP-violating condition can be fulfilled by a purely thermal kinetic phase from the wavefunction correction in the lepton-doublet sector, which has been neglected in most leptogenesis-based setup. Furthermore, this condition necessitates a preferred flavor basis in which both the charged-lepton and neutrino Yukawa matrices are non-diagonal. To protect such a proper Yukawa structure from the basis transformations in flavor space prior to the electroweak gauge symmetry breaking, we can resort to a plethora of model buildings aimed at deciphering the non-trivial Yukawa structures. Interestingly, based on the well-known tri-bimaximal mixing with a minimal correction from the charged-lepton or neutrino sector, we find that a simultaneous explanation of the baryon-number asymmetry in the Universe and the low-energy neutrino oscillation observables can be attributed to the mixing angle and the CP-violating phase introduced in the minimal correction.

   hep-phhep-exEPJC(2020)·12 citations
10. 10*

    Evading the Grossman-Nir bound with $\Delta I=3/2$ new physics

    Xiao-Gang He🇹🇼 · Xiao-Dong Ma🇹🇼 · Jusak Tandean🇹🇼 · German Valencia🇦🇺

    Rare kaon decays with missing energy, $K\to \pi$+$E_{\mathrm{miss}}$, have received considerable attention because their rates can be calculated quite precisely within the standard model (SM), where the missing energy is carried away by an undetected neutrino-antineutrino pair. Beyond the SM, clean theoretical predictions can also be made regarding these processes. One such prediction is the so-called Grossman-Nir (GN) bound, which states that the branching fractions of the $K_L$ and $K^{+}$ modes must satisfy the relation $\mathcal{B}(K_L\to {\pi }^0$+$E_{\mathrm{miss}})\lesssim 4.3\mathcal{B}(K^{+}\to {\pi }^{+}$+$E_{\mathrm{miss}})$ and applies within and beyond the SM, as long as the hadronic transitions change isospin by $\Delta I=1/2$. In this paper we extend the study of these modes to include new-physics scenarios where the missing energy is due to unobserved lepton-number-violating neutrino pairs, invisible light new scalars, or pairs of such scalars. The new interactions are assumed to arise above the electroweak scale and described by an effective field theory. We explore the possibility of violating the GN bound through $\Delta I=3/2$ contributions to the $K\to \pi$ transitions within these scenarios and find that large violations are only possible in the case where the missing energy is due to an invisible light new scalar.

    hep-phhep-exJHEP(2020)·31 citations
11. 11*

    Renormalization and Scale Evolution of the Soft-Quark Soft Function

    Ze Long Liu (LANL)🇺🇸 · Bianka Mecaj (U. Mainz)🇩🇪 · Matthias Neubert (U. Mainz & Cornell)🇩🇪 · Xing Wang (U. Mainz)🇩🇪 · Sean Fleming (U. Mainz & U. Arizona)🇺🇸

    Soft functions defined in terms of matrix elements of soft fields dressed by Wilson lines are central components of factorization theorems for cross sections and decay rates in collider and heavy-quark physics. While in many cases the relevant soft functions are defined in terms of gluon operators, at subleading order in power counting soft functions containing quark fields appear. We present a detailed discussion of the properties of the soft-quark soft function consisting of a quark propagator dressed by two finite-length Wilson lines connecting at one point. This function enters in the factorization theorem for the Higgs-boson decay amplitude of the $h\to \gamma \gamma$ process mediated by light-quark loops. We perform the renormalization of this soft function at one-loop order, derive its two-loop anomalous dimension and discuss solutions to its renormalization-group evolution equation in momentum space, in Laplace space and in the "diagonal space", where the evolution is strictly multiplicative.

    hep-phhep-thJHEP(2020)·48 citations
12. 12*

    Predictions for $\mathrm{Z}$-boson production in association with a $\mathrm{b}$-jet at $\mathcal{O}({\alpha }_s^3)$

    R. Gauld🇳🇱 · A. Gehrmann-De Ridder🇨🇭 · E. W. N. Glover🇬🇧 · A. Huss🇨🇭 · I. Majer🇨🇭

    Precise predictions are provided for the production of a $\mathrm{Z}$-boson and a $\mathrm{b}$-jet in hadron-hadron collisions within the framework of perturbative QCD, at $\mathcal{O}({\alpha }_s^3)$. To obtain these predictions we perform the first calculation of a hadronic scattering process involving the direct production of a flavoured-jet at next-to-next-to-leading order accuracy in massless QCD, and extend techniques to also account for the impact of finite heavy-quark mass effects. The predictions are compared to CMS data obtained in $\mathrm{pp}$ collisions at a centre-of-mass energy of $8\mathrm{TeV}$, which are the most precise data from Run I of the LHC for this process, where a good description of the data is achieved. To allow this comparison we have performed an unfolding of the data, which overcomes the long-standing issue that the experimental and theoretical definitions of jet flavour are incompatible.

    hep-phhep-exPRL(2020)·47 citations
13. 13*

    Probing neutrino quantum decoherence at reactor experiments

    André de Gouvêa🇺🇸 · Valentina De Romeri🇪🇸 · Christoph A. Ternes🇪🇸

    We explore how well reactor antineutrino experiments can constrain or measure the loss of quantum coherence in neutrino oscillations. We assume that decoherence effects are encoded in the size of the neutrino wave-packet, $\sigma$. We find that the current experiments Daya Bay and the Reactor Experiment for Neutrino Oscillation (RENO) already constrain $\sigma >1.0\times 10^{-4}$ nm and estimate that future data from the Jiangmen Underground Neutrino Observatory (JUNO) would be sensitive to $\sigma <2.1\times 10^{-3}$ nm. If the effects of loss of coherence are within the sensitivity of JUNO, we expect $\sigma$ to be measured with good precision. The discovery of nontrivial decoherence effects in JUNO would indicate that our understanding of the coherence of neutrino sources is, at least, incomplete.

    hep-phhep-exJHEP(2020)·54 citations
14. 14*

    A Measurable Angular Distribution for $\bar{B}\to D^{\ast }{\tau }^{-}{\bar{\nu }}_{\tau }$ Decays

    Bhubanjyoti Bhattacharya🇺🇸 · Alakabha Datta🇺🇸 · Saeed Kamali🇺🇸 · David London🇨🇦

    At present, the measurements of $R_{D^{(\ast )}}$ and $R_{J/\psi }$ hint at new physics (NP) in $b\to c{\tau }^{-}\bar{\nu }$ decays. The angular distribution of $\bar{B}\to D^{\ast }(\to D\pi ){\tau }^{-}{\bar{\nu }}_{\tau }$ would be useful for getting information about the NP, but it cannot be measured. The reason is that the three-momentum ${\vec{p}}_{\tau }$ cannot be determined precisely since the decay products of the ${\tau }^{-}$ include an undetected ${\nu }_{\tau }$. In this paper, we construct a measurable angular distribution by considering the additional decay ${\tau }^{-}\to {\pi }^{-}{\nu }_{\tau }$. The full process is $\bar{B}\to D^{\ast }(\to D{\pi }^{\prime }){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$, which includes three final-state particles whose three-momenta can be measured: $D$, ${\pi }^{\prime }$, ${\pi }^{-}$. The magnitudes and relative phases of all the NP parameters can be extracted from a fit to this angular distribution. One can measure CP-violating angular asymmmetries. If one integrates over some of the five kinematic parameters parametrizing the angular distribution, one obtains (i) familiar observables such as the $q^2$ distribution and the $D^{\ast }$ polarization, and (ii) new observables associated with the ${\pi }^{-}$ emitted in the $\tau$ decay: the forward-backward asymmetry of the ${\pi }^{-}$ and the CP-violating triple-product asymmetry.

    hep-phhep-exJHEP(2020)·41 citations
15. 15*

    Sterile neutrino dark matter: Impact of active-neutrino opacities

    Dietrich Bodeker🇩🇪 · Alexander Klaus🇩🇪

    The resonant production of keV sterile-neutrino dark matter mainly takes place during the QCD epoch of the early universe. It has been argued that it could be strongly affected by the opacities (or damping rates) of active neutrinos, which receive non-perturbative QCD-contributions. We find that for lepton asymmetries $n_{L_{\alpha }}/s$ below $10^{-6}$ the opacities significantly affect the sterile-neutrino yield, but that for larger asymmetries, which are necessary for producing a significant fraction of the dark matter, the yield is insensitive to changes of the opacities. Thus non-perturbative QCD contributions to the opacities at temperatures around 160 MeV will not affect this dark matter scenario. We obtain larger sterile-neutrino yields than previous studies, and thus weaker lower limits on the active-sterile mixing angle from Big Bang Nucleosynthesis.

    hep-phJHEP(2020)·16 citations
16. 16*

    Convex Geometry Perspective to the (Standard Model) Effective Field Theory Space

    Cen Zhang🇨🇳 · Shuang-Yong Zhou🇨🇳

    We present a convex geometry perspective to the Effective Field Theory (EFT) parameter space. We show that the second $s$ derivatives of the forward EFT amplitudes form a convex cone, whose extremal rays are closely connected with states in the UV theory. For tree-level UV-completions, these rays are simply theories with all UV particles living in at most one irreducible representation of the symmetries of the theory. In addition, all the extremal rays are determined by the symmetries and can be systematically identified via group theoretical considerations. The implications are twofold. First, geometric information encoded in the EFT space can help reconstruct the UV-completion. In particular, we will show that the dim-8 operators are important in reverse-engineering the UV physics from the Standard Model EFT, and thus deserve more theoretical and experimental investigations. Second, theoretical bounds on the Wilson coefficients can be obtained by identifying the boundaries of the cone and are in general stronger than the current positivity bounds. We show explicit examples of these new bounds, and demonstrate that they originate from the scattering amplitudes corresponding to entangled states.

    hep-phhep-thPRL(2020)·118 citations
17. 17*

    Exceptional Unification of Families and Forces

    Alfredo Aranda🇲🇽 · Francisco J. de Anda🇲🇽 · Stephen F. King🇬🇧

    This work considers the remarkable suggestion that the three families of quarks and leptons may be unified, together with the Higgs and gauge fields of the Standard Model (SM), into a single "particle", namely the $\text{248}$ vector superfield of a ten-dimensional $E_8$ super Yang Mills (SYM) theory. Towards a realistic model along these lines, a class of orbifoldings based on $T^6/({\mathbb{Z}}_N\times {\mathbb{Z}}_M)$ are proposed and explored, that can in principle break $E_8$ SYM down to the minimal supersymmetric standard model (MSSM), embedded in a larger group such as $E_6$, $SO(10)$ or $SU(5)$, together with other gauge group factors which can be broken by Wilson lines. A realistic model based on $T^6/({\mathbb{Z}}_6\times {\mathbb{Z}}_2)$ is presented. The orbifold breaks $E_8$ SYM down to a Pati-Salam gauge group in 4d, together with other gauge groups, which are further broken to the SM by Wilson lines in the right-handed sneutrino directions, yielding proto-realistic fermion mass matrices, and experimental signals associated with a low Pati-Salam gauge group breaking scale.

    hep-phNPB(2020)·9 citations
18. 18*

    The Smallest SU($N$) Hadrons

    Stefano Profumo🇺🇸

    If new physics contains new, heavy strongly-interacting particles belonging to irreducible representations of SU(3) different from the adjoint or the (anti)fundamental, it is a non-trivial question to calculate what is the minimum number of quarks/antiquarks/gluons needed to form a color-singlet bound state ("hadron"), or, perturbatively, to form a gauge-invariant operator, with the new particle. Here, I prove that for an SU(3) irreducible representation with Dynkin label $(p,q)$, the minimal number of quarks needed to form a product that includes the (0,0) representation is $2p+q$. I generalize this result to SU($N$), with $N>3$. I also calculate the minimal total number of quarks/antiquarks/gluons that, bound to a new particle in the $(p,q)$ representation, give a color-singlet state, or, equivalently, the smallest-dimensional gauge-invariant operator that includes quark/antiquark/gluon fields and the new strongly-interacting matter field. Finally, I list all possible values of the electric charge of the smallest hadrons containing the new exotic particles, and discuss constraints from asymptotic freedom both for QCD and for grand unification embeddings thereof.

    ↳ hep-thastro-ph.HEhep-phPRD(2020)·3 citations
19. 19*

    Deep Learning and AdS/QCD

    Tetsuya Akutagawa🇯🇵 · Koji Hashimoto🇯🇵 · Takayuki Sumimoto🇯🇵

    We propose a deep learning method to build an AdS/QCD model from the data of hadron spectra. A major problem of generic AdS/QCD models is that a large ambiguity is allowed for the bulk gravity metric with which QCD observables are holographically calculated. We adopt the experimentally measured spectra of $\rho$ and $a_2$ mesons as training data, and perform a supervised machine learning which determines concretely a bulk metric and a dilaton profile of an AdS/QCD model. Our deep learning (DL) architecture is based on the AdS/DL correspondence (arXiv:1802.08313) where the deep neural network is identified with the emergent bulk spacetime.

    ↳ hep-thcond-mat.dis-nnhep-phPRD(2020)·61 citations
20. 20*

    Search for Axionlike and Scalar Particles with the NA64 Experiment

    D. Banerjee🇨🇭 · J. Bernhard🇨🇭 · V.E. Burtsev🇷🇺 · A.G. Chumakov🇷🇺 · D. Cooke🇬🇧 · P. Crivelli🇨🇭 · E. Depero🇨🇭 · A.V. Dermenev🇷🇺 · S.V. Donskov🇷🇺 · R.R. Dusaev🇷🇺 · T. Enik🇷🇺 · N. Charitonidis🇨🇭 and 43 other authors

    We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by the nuclei of the dump. The a(s) would penetrate the downstream HCAL module, serving as shielding, and would be observed either through their $a(s)\to \gamma \gamma$ decay in the rest of the HCAL detector or as events with large missing energy if the a(s) decays downstream of the HCAL. This method allows for the probing the a(s) parameter space, including those from generic axion models, inaccessible to previous experiments. No evidence of such processes has been found from the analysis of the data corresponding to $2.84\times 10^{11}$ electrons on target allowing to set new limits on the $a(s)\gamma \gamma$-coupling strength for a(s) masses below 55 MeV.

    ↳ hep-exhep-phPRL(2020)·215 citations
21. 21*

    Was GW170817 a canonical neutron star merger? Bayesian analysis with a third family of compact stars

    David Blaschke🇵🇱 · Alexander Ayriyan🇷🇺 · David Alvarez-Castillo🇵🇱 · Hovik Grigorian🇷🇺

    We investigate the possibility that GW170817 has not been the merger of two conventional neutron stars (NS) but involved at least one if not two hybrid stars with a quark matter core which might even belong to a third family of compact stars. To this end, we develop a Bayesian analysis method for selecting the most probable equation of state (EoS) under a set of constraints from compact star physics, which now also include the tidal deformability from GW170817 and the first result for the mass and radius determination for PSR J0030+0451 by NICER. We apply this method for the first time to a two-parameter family of hybrid EoS based on the DD2 model with nucleonic excluded volume for hadronic matter and the color superconducting generalized nlNJL model for quark matter. The model has a variable onset of deconfinement and can mimic the effects of pasta phases with the possibility of a third family of hybrid stars in the mass-radius ($M-R$) diagram. The main findings of this study are that: 1) the presence of multiple configurations for a given mass (twins) corresponds to a set of disconnected lines in the diagram of tidal deformabilities for binary mergers, so that merger events from the same mass range may result in a probability landscape with different peak positions; 2) the Bayesian analysis with the above observational constraints favors an early onset of the deconfinement transition, at masses of $M_{\mathrm{onset}}\le 0.8M_{\odot }$ with a $M-R$ relationship that in the range of observed neutron star masses is almost indistinguishable from that of a soft hadronic APR EoS; 3) a few yet fictitious measurements of the NICER experiment with a $1\sigma$ range that is half of the present value and different mass and radius would change the posterior likelihood so that hybrid EoS with a phase transition onset in the range $M_{\mathrm{onset}}=1.1-1.6M_{\odot }$ would be favored.

    ↳ astro-ph.HEhep-phnucl-thUniverse(2020)·84 citations
22. 22*

    Transport and hydrodynamics in the chiral limit

    Eduardo Grossi🇺🇸 · Alexander Soloviev🇺🇸 · Derek Teaney🇺🇸 · Fanglida Yan🇺🇸

    We analyze the evolution of hydrodynamic fluctuations for QCD matter below $T_c$ in the chiral limit, where the pions (the Goldstone modes) must be treated as additional non-abelian superfluid degrees of freedom, reflecting the broken $S{U}_L(2)\times S{U}_R(2)$ symmetry of the theory. In the presence of a finite pion mass $m_{\pi }$, the hydrodynamic theory is ordinary hydrodynamics at long distances, and superfluid-like at short distances. The presence of the superfluid degrees of freedom then gives specific contributions to the bulk viscosity, the shear viscosity, and diffusion coefficients of the ordinary theory at long distances which we compute. This determines, in some cases, the leading dependence of the transport parameters of QCD on the pion mass. We analyze the predictions of this computation, as the system approaches the $O(4)$ critical point.

    ↳ hep-thhep-phnucl-thPRD(2020)·50 citations
23. 23*

    Observability of Dark Matter Substructure with Pulsar Timing Correlations

    Harikrishnan Ramani🇺🇸 · Tanner Trickle🇺🇸 · Kathryn M. Zurek🇺🇸

    Dark matter substructure on small scales is currently weakly constrained, and its study may shed light on the nature of the dark matter. In this work we study the gravitational effects of dark matter substructure on measured pulsar phases in pulsar timing arrays (PTAs). Due to the stability of pulse phases observed over several years, dark matter substructure around the Earth-pulsar system can imprint discernible signatures in gravitational Doppler and Shapiro delays. We compute pulsar phase correlations induced by general dark matter substructure, and project constraints for a few models such as monochromatic primordial black holes (PBHs), and Cold Dark Matter (CDM)-like NFW subhalos. This work extends our previous analysis, which focused on static or single transiting events, to a stochastic analysis of multiple transiting events. We find that stochastic correlations, in a PTA similar to the Square Kilometer Array (SKA), are uniquely powerful to constrain subhalos as light as $\sim 10^{-13}{M}_{\odot }$, with concentrations as low as that predicted by standard CDM.

    ↳ astro-ph.COastro-ph.HEhep-phJCAP(2020)·84 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.