Fri·Nov 17, 2017Friday·November 17, 2017

1. 01*

   Bottom and Charm Mass determinations from global fits to $Q\bar{Q}$ bound states at N${}^3$LO

   Vicent Mateu🇪🇸 · Pablo G. Ortega🇪🇸

   The bottomonium spectrum up to $n=3$ is studied within Non-Relativistic Quantum Chromodynamics up to N${}^3$LO. We consider finite charm quark mass effects both in the QCD potential and the $\overline{\mathrm{MS}}$-pole mass relation up to third order in the ${\rm Y}$-scheme counting. The $u=1/2$ renormalon of the static potential is canceled by expressing the bottom quark pole mass in terms of the MSR mass. A careful investigation of scale variation reveals that, while $n=1,2$ states are well behaved within perturbation theory, $n=3$ bound states are no longer reliable. We carry out our analysis in the $n_{\ell }=3$ and $n_{\ell }=4$ schemes and conclude that, as long as finite $m_c$ effects are smoothly incorporated in the MSR mass definition, the difference between the two schemes is rather small. Performing a fit to $b\bar{b}$ bound states we find ${\overline{m}}_b({\overline{m}}_b)=4.216\pm 0.039$ GeV. We extend our analysis to the lowest lying charmonium states finding ${\overline{m}}_c({\overline{m}}_c)=1.273\pm 0.054$ GeV. Finally, we perform simultaneous fits for ${\overline{m}}_b$ and ${\alpha }_s$ finding ${\alpha }_s^{(n_f=5)}(m_Z)=0.1178\pm 0.0051$. Additionally, using a modified version of the MSR mass with lighter massive quarks we are able to predict the uncalculated $\mathcal{O}({\alpha }_s^4)$ virtual massive quark corrections to the relation between the $\overline{\mathrm{MS}}$ and pole masses.

   hep-phJHEP(2018)·53 citations
2. 02*

   The Impact of LHC Jet Data on the MMHT PDF Fit at NNLO

   L. A. Harland-Lang🇬🇧 · A. D. Martin🇬🇧 · R. S. Thorne🇬🇧

   We investigate the impact of the high precision ATLAS and CMS 7 TeV measurements of inclusive jet production on the MMHT global PDF analysis at next-to-next-to-leading order (NNLO). This is made possible by the recent completion of the long-term project to calculate the NNLO corrections to the hard cross section. We find that a good description of the ATLAS data is not possible with the default treatment of experimental systematic errors, and develop a simplified solution that retains the dominant physical information of the data. We then investigate the fit quality and the impact on the gluon PDF central value and uncertainty when the ATLAS and CMS data are included in a MMHT fit. We consider both common choices for the factorization and renormalization scale, namely the inclusive jet transverse momentum, $p_{\perp }$, and the leading jet $p_{\perp }$, as well as the different jet radii for which the ATLAS and CMS data are made available. We find that the impact of these data on the gluon is relatively insensitive to these inputs, in particular the scale choice, while the inclusion of NNLO corrections tends to improve the data description somewhat, and gives a qualitatively similar though not identical impact on the gluon in comparison to NLO.

   hep-phhep-exEPJC(2018)·61 citations
3. 03*

   Exploring a Non-Minimal Sterile Neutrino Model Involving Decay at IceCube and Beyond

   Zander Moss🇺🇸 · Marjon H. Moulai🇺🇸 · Carlos A. Argüelles🇺🇸 · Janet M. Conrad🇺🇸

   We study the phenomenology of neutrino decay together with neutrino oscillations in the context of eV-scale sterile neutrinos. We review the formalism of visible neutrino decay in which one of the decay products is a neutrino that potentially can be observed. We apply the formalism developed for decay to the recent sterile neutrino search performed by IceCube with TeV neutrinos. We show that for ${\nu }_4$ lifetime ${\tau }_4/m_4\lesssim 10^{-16}\mathrm{e}{\mathrm{V}}^{-1}\mathrm{s}$, the interpretation of the high-energy IceCube analysis can be significantly changed.

   hep-phhep-exPRD(2018)·56 citations
4. 04*

   The new $a_1(1420)$ state: structure, mass and width

   H. Sundu🇹🇷 · S. S. Agaev🇦🇿 · K. Azizi🇹🇷

   The structure, spectroscopic parameters and width of the resonance with quantum numbers $J^{PC}=1^{++}$ discovered by the COMPASS Collaboration and classified as the $a_1(1420)$ meson are examined in the context of QCD sum rule method. In the calculations the axial-vector meson $a_1(1420)$ is treated as a four-quark state with the diquark-antidiquark structure. The mass and current coupling of $a_1(1420)$ are evaluated using QCD two-point sum rule approach. Its observed decay mode $a_1(1420)\to f_0(980)\pi$, and kinematically allowed ones, namely $a_1\to K^{\ast \pm }{K}^{\mp }$, $a_1\to K^{\ast 0}{\bar{K}}^0$ and $a_1\to {\bar{K}}^{\ast 0}{K}^0$ channels are studied employing QCD sum rules on the light-cone. Our prediction for the mass of the $a_1(1420)$ state $m_{a_1}=1416_{-79}^{+81}\mathrm{MeV}$ is in excellent agreement with the experimental result. Width of this state $\Gamma =145.52\pm 20.79\mathrm{MeV}$ within theoretical and experimental errors is also in accord with the COMPASS data.

   hep-phhep-exhep-latPRD(2018)·15 citations
5. 05*

   Photoproduction of Upsilon in Ultraperipheral Collisions at LHC Run2 energies

   Dipanwita Dutta🇮🇳 · Ruchi Chudasama🇮🇳

   The exclusive ${\rm Y}$ photoproduction in ultraperipheral proton-nucleus and nucleus-nucleus collisions at LHC energies is being investigated using pQCD framework which constrain the gluon distribution in the proton and nuclei at low $x$. Rapidity distributions of ${\rm Y}$ photoproduction with different gluon distribution parameterization and gluon shadowing for nuclear PDFs including photon flux suppression for strong interaction, are being presented at LHC energies. Predictions done for ultraperipheral collisions at $\sqrt{s}$=$8.16$ TeV in pPb, and at $\sqrt{s}$=$5.02$ TeV in PbPb collisions which are LHC Run 2 Heavy Ion collision scenario and measurements of cross-section will be available soon.

   hep-ph0 citations
6. 06*

   Quasi-PDFs and pseudo-PDFs

   Anatoly Radyushkin🇺🇸

   We discuss the physical nature of quasi-PDFs, especially the reasons for the strong nonperturbative evolution pattern which they reveal in actual lattice gauge calculations. We argue that quasi-PDFs may be treated as hybrids of PDFs and the rest-frame momentum distributions of partons. The latter is also responsible for the transverse momentum dependence of TMDs. The resulting convolution structure of quasi-PDFs necessitates using large probing momenta $p_3\gtrsim 3$ GeV to get reasonably close to the PDF limit. To deconvolute the rest-frame distribution effects, we propose to use a method based directly on the coordinate representation. We treat matrix elements $M(z_3,p_3)$ as distributions $\mathcal{M}(\nu ,z_3^2)$ depending on the Ioffe-time $\nu =p_3{z}_3$ and the distance parameter $z_3^2$. The rest-frame spatial distribution is given by $\mathcal{M}(0,z_3^2)$. Using the reduced Ioffe function $\mathfrak{M}(\nu ,z_3^2)\equiv \mathcal{M}(\nu ,z_3^2)/\mathcal{M}(0,z_3^2)$ we divide out the rest frame effects,including the notorious link renormalization factors. The $\nu$-dependence remains intact and determines the shape of PDFs in the small $z_3$ region. The residual $z_3^2$ dependence of the $\mathfrak{M}(\nu ,z_3^2)$ is governed by perturbative evolution. The Fourier transform of $\mathcal{M}(\nu ,z_3^2)$ produces pseudo-PDFs $\mathcal{P}(x,z_3^2)$ that generalize the light-front PDFs onto spacelike intervals. On the basis of these findings we propose a new method for extraction of PDFs from lattice calculations.

   hep-phhep-latPoS(2017)·17 citations
7. 07*

   Revisiting the high-scale validity of Type-II seesaw model with novel LHC signature

   Dilip Kumar Ghosh🇮🇳 · Nivedita Ghosh🇮🇳 · Ipsita Saha🇮🇹 · Avirup Shaw🇮🇳

   The Type-II seesaw model is a well-motivated new physics scenario to address the origin of the neutrino mass issue. We show that this model can easily accommodate an absolutely stable vacuum until the Planck scale, however with strong limit on the exotic scalar masses and the corresponding mixing angle. We examine the model prediction at the current and future high luminosity run of the Large Hadron Collider (LHC) for the scalar masses and mixing angles fixed at such high-scale valid region. Specifically, we device the associated and pair production of the charged scalars as a new probe of the model at the LHC. We show that for a particular signal process the model can be tested with $5\sigma$ signal significance even at the present run of the LHC.

   hep-phPRD(2018)·57 citations
8. 08*

   The adaptive Monte Carlo toolbox for phase space integration and generation

   R. A. Kycia🇵🇱 · J. Turnau🇵🇱 · J. J. Chwastowski🇵🇱 · R. Staszewski🇵🇱 · M. Trzebiński🇵🇱

   An implementation of the Monte Carlo (MC) phase space generators coupled with adaptive MC integration/simulation program FOAM is presented. The first program is a modification of the classic phase space generator GENBOD interfaced with the adaptive sampling integrator/generator FOAM. On top of this tool the algorithm suitable for generation of the phase space for an reaction with two leading particles is presented (double-peripheral process with central production of particles). At the same time it serves as an instructive example of construction of a self-adaptive phase space generator/integrator with a modular structure for specialized particle physics calculations.

   hep-phCommun.Comput.Phys.(2019)·13 citations
9. 09*

   Variations on Photon Vacuum Polarization

   Fred Jegerlehner🇩🇪

   I provide updates for the theoretical predictions of the muon and electron anomalous magnetic moments, for the shift in the fine structure constant $\alpha (M_Z)$ and for the weak mixing parameter ${\sin }^2{\Theta }_W(M_Z)$. Phenomenological results for Euclidean time correlators, the key objects in the lattice QCD approach to hadronic vacuum polarization, are briefly considered. Furthermore, I present a list of isospin breaking and electromagnetic corrections for the lepton moments, which may be used to supplement lattice QCD results obtained in the isospin limit and without the e.m. corrections.

   hep-phEPJ Web Conf.(2019)·84 citations
10. 10*

    Zimmermann's Forest Formula, Infrared Divergences and the QCD Beta Function

    Franz Herzog🇳🇱

    We review Zimmermann's forest formula, which solves Bogoliubov's recursive $R$-operation for the subtraction of ultraviolet divergences in perturbative Quantum Field Theory. We further discuss a generalisation of the $R$-operation which subtracts besides ultraviolet also Euclidean infrared divergences. This generalisation, which goes under the name of the $R^{\ast }$-operation, can be used efficiently to compute renormalisation constants. We will discuss several results obtained by this method with focus on the QCD beta function at five loops as well as the application to hadronic Higgs boson decay rates at N${}^4$LO. This article summarizes a talk given at the Wolfhart Zimmermann Memorial Symposium.

    hep-phhep-thNPB(2018)·16 citations
11. 11*

    Double heavy tri-hadron bound state via delocalized $\pi$ bond

    Li Ma🇩🇪 · Qian Wang🇩🇪 · Ulf-G. Meißner🇩🇪

    The number of exotic candidates which are beyond the conventional quark model has grown dramatically during the last decades. Some of them could be viewed as analogues of the deuteron. Similarly, the existence of the triton indicates that bound states formed by three hadrons could also exist. To illustrate this possibility, we study the $D{D}^{\ast }K$ and $B{B}^{\ast }\bar{K}$ systems by using the Born-Oppenheimer Approximation. To leading order, only one-pion exchange potentials are considered, which means that the three constitutes share one virtual pion. That is similar to the role of the delocalized $\pi$ bond for the formation of Benzene in chemistry. After solving the Schrödinger equation, we find two three-body $D{D}^{\ast }K$ and $B{B}^{\ast }\bar{K}$ bound states with masses $4317.92_{-4.32}^{+3.66}\mathrm{MeV}$ and $11013.65_{-8.84}^{+8.49}\mathrm{MeV}$, respectively. The masses of their $D{\bar{D}}^{\ast }K$ and $B{\bar{B}}^{\ast }\bar{K}$ analogues are $4317.92_{-6.55}^{+6.13}\mathrm{MeV}$ and $11013.65_{-9.02}^{+8.68}\mathrm{MeV}$. From the experimental side, the $D{\bar{D}}^{\ast }K$ bound state could be found by analyzing the current world data of the $B\to J/\psi \pi \pi K$ process by focusing on the $J/\psi \pi K$ channel. Its confirmation could also help to understand the formation of kaonic nuclei in nuclear physics.

    hep-phnucl-thCPC(2019)·35 citations
12. 12*

    The photon polarization tensor in pulsed Hermite- and Laguerre-Gaussian beams

    Felix Karbstein🇩🇪 · Elena A. Mosman🇷🇺

    In this article, we provide analytical expressions for the photon polarization tensor in pulsed Hermite- and Laguerre-Gaussian laser beams. Our results are based on a locally constant field approximation of the one-loop Heisenberg-Euler effective Lagrangian for quantum electrodynamics. Hence, by construction they are limited to slowly varying electromagnetic fields, varying on spatial and temporal scales significantly larger than the Compton wavelength/time of the electron. The latter criterion is fulfilled by all laser beams currently available in the laboratory. Our findings will, e.g., be relevant for the study of vacuum birefringence experienced by probe photons brought into collision with a high-intensity laser pulse which can be represented as a superposition of either Hermite- or Laguerre-Gaussian modes.

    hep-phPRD(2017)·29 citations
13. 13*

    Can one ever prove that neutrinos are Dirac particles?

    Martin Hirsch🇪🇸 · Rahul Srivastava🇪🇸 · José W. F. Valle🇪🇸

    According to the "Black Box" theorem the experimental confirmation of neutrinoless double beta decay ($0\nu 2\beta$) would imply that at least one of the neutrinos is a Majorana particle. However, a null $0\nu 2\beta$ signal cannot decide the nature of neutrinos, as it can be suppressed even for Majorana neutrinos. In this letter we argue that if the null $0\nu 2\beta$ decay signal is accompanied by a $0\nu 4\beta$ quadruple beta decay signal, then at least one neutrino should be a Dirac particle. This argument holds irrespective of the underlying processes leading to such decays.

    hep-phhep-exnucl-exnucl-thPLB(2018)·58 citations
14. 14*

    General Continuum Clockwork

    Kiwoon Choi🇰🇷 · Sang Hui Im🇩🇪 · Chang Sub Shin🇰🇷

    The continuum clockwork is an extra-dimensional set-up to realize certain features of the clockwork mechanism generating exponentially suppressed or hierarchical couplings of light particles. We study the continuum clockwork in a general scheme in which large volume, warped geometry, and localization of zero modes in extra dimension are described by independent parameters. For this, we propose a generalized 5-dimensional linear dilaton model which can realize such set-up as a solution of the model, and examine the KK spectrum and the couplings of zero modes and massive KK modes to boundary-localized operators for the bulk graviton, Abelian gauge bosons and periodic scalar fields. We discuss how those KK spectra and couplings vary as a function of the volume, warping and localization parameters, and highlight the behavior in the parameter region corresponding to the clockwork limit. We discuss also the field range of 4-dimensional axions originating from either 5-dimensional periodic scalar field or the 5-th component of an Abelian gauge field, and comment on the limitations of continuum clockwork compared to the discrete clockwork.

    hep-phhep-thJHEP(2018)·27 citations
15. 15*

    Can One have Significant Deviations from Leptonic $3\times 3$ Unitarity in the Framework of Type I Seesaw Mechanism?

    Nuno Rosa Agostinho🇪🇸 · G. C. Branco🇵🇹 · Pedro M. F. Pereira🇵🇹 · M. N. Rebelo🇵🇹 · J. I. Silva-Marcos🇵🇹

    We address the question of deviations from $3\times 3$ unitarity of the leptonic mixing matrix showing that, contrary to conventional wisdom, one may have significant deviations from unitarity in the framework of type I seesaw mechanism. In order for this scenario to be feasible, at least one of the heavy neutrinos must have a mass at the TeV scale, while the other two may have much larger masses. We present specific examples where deviations from $3\times 3$ unitarity are sufficiently small to conform to all the present stringent experimental bounds but are sufficiently large to have the potential for being detectable at the next round of experiments.

    hep-phEPJC(2018)·41 citations
16. 16*

    Effect of the chromo-electromagnetic field fluctuations on heavy quark propagation at the LHC energies

    Ashik Ikbal Sheikh🇮🇳 · Zubayer Ahammed🇮🇳 · Prashant Shukla🇮🇳 · Munshi G. Mustafa🇮🇳

    We consider the effect of the chromo-electromagnetic field fluctuations in addition to the collisional as well as the radiative energy loss suffered by heavy quarks while propagating through the hot and densed deconfined medium of quarks and gluons created in relativistic heavy ion collisions. The chromo-electromagnetic field fluctuations play an important role as it leads to an energy gain of heavy quarks of all momentum, significantly effective at the lower momentum region. With this, we have computed, for the first time, the nuclear modification factor (R_{AA}) of heavy mesons, viz., D-mesons and B-mesons and compared with the those experimental measurements in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV and \sqrt{s_{NN}} = 5.02 TeV by the CMS and ALICE experiments at the LHC. Our results are found to be in very good agreement with those available data measured by CMS and ALICE experiments.

    hep-phnucl-thPRC(2018)·8 citations
17. 17*

    Cosmological Axion and Quark Nugget Dark Matter Model

    Shuailiang Ge🇨🇦 · Xunyu Liang🇨🇦 · Ariel Zhitnitsky🇨🇦

    We study a dark matter (DM) model offering a very natural explanation of two (naively unrelated) problems in cosmology: the observed relation ${\Omega }_{\mathrm{DM}}\sim {\Omega }_{\mathrm{visible}}$ and the observed asymmetry between matter and antimatter in the Universe, known as the "baryogenesis" problem. In this framework, both types of matter (dark and visible) have the same QCD origin, form at the same QCD epoch, and both proportional to one and the same dimensional parameter of the system, ${\Lambda }_{\mathrm{QCD}}$, which explains how these two, naively distinct, problems could be intimately related, and could be solved simultaneously within the same framework. More specifically, the DM in this model is composed by two different ingredients: the (well- studied) DM axions and (less-studied) the quark nuggets made of matter or antimatter. The focus of the present work is the quantitative analysis of the relation between these two distinct components contributing to the dark sector of the theory determined by ${\Omega }_{\mathrm{DM}}\equiv [{\Omega }_{\mathrm{DM}}(\mathrm{nuggets})+{\mathrm{\Omega }}_{\mathrm{DM}}(\mathrm{axion})]$. We argue that the nugget's DM component always traces the visible matter density, i.e. ${\Omega }_{\mathrm{DM}}(\mathrm{nuggets})\sim {\mathrm{\Omega }}_{\mathrm{visible}}$ and this feature is not sensitive to the parameters of the system such as the axion mass $m_a$ or the misalignment angle ${\theta }_0$. It should be contrasted with conventional axion production mechanism due to the misalignment when ${\Omega }_{\mathrm{DM}}(\mathrm{axion})$ is highly sensitive to the axion mass $m_a$ and the initial misalignment angle ${\theta }_0$. We also discuss the constraints on this model related to the inflationary scale $H_I$, non-observation of the isocurvature perturbations, $r_T<0.12$, and also, varies axions search experiments.

    hep-phastro-ph.COPRD(2018)·55 citations
18. 18*

    Heavy quark radiation in NLO+PS POWHEG generators

    L. Buonocore🇮🇹 · P. Nason🇨🇭 · F. Tramontano🇮🇹

    In this paper we deal with radiation from heavy quarks in the context of next-to-leading order calculations matched to parton shower generators. A new algorithm for radiation from massive quarks is presented that has considerable advantages over the one previously employed. We implement the algorithm in the framework of the $\mathtt{POWHEG}-\mathtt{BOX}$, and compare it with the previous one in the case of the $\mathtt{hvq}$ generator for bottom production in hadronic collisions, and in the case of the $bb4l$ generator for top production and decay.

    hep-phEPJC(2018)·15 citations
19. 19*

    Impact of Beauty and Charm H1-ZEUS Combined Measurements on PDFs and Determination of the Strong Coupling

    A. Vafaee🇮🇷 · A. Khorramian🇮🇷

    In this QCD analysis, we investigate the impact of recent measurements of heavy-flavor charm and beauty cross sections data sets on the simultaneous determination of Parton Distribution Functions (PDFs) and the strong coupling, ${\alpha }_s(M_Z^2)$. We perform three different fits based on Variable-Flavour Number Scheme (VFNS) at the Leading Order (LO) and Next-to-Leading Order (NLO) and choose the full HERA run I and II combined data as a new measurement of inclusive Deep Inelastic Scattering (DIS) cross sections for our base data set. We show that including charm and beauty cross sections data reduces the uncertainty of gluon distribution and improves the fit quality up to 4.1\% from leading order to next-to-leading order and up to 1.7\% for only NLO without and with beauty and charm data contributions.

    hep-phEPJA(2017)·7 citations
20. 20*

    Towards a non-perturbative calculation of Weak Hamiltonian Wilson coefficients

    Mattia Bruno🇺🇸 · Christoph Lehner🇺🇸 · Amarjit Soni🇺🇸

    We propose a method to compute the Wilson coefficients of the weak effective Hamiltonian to all orders in the strong coupling constant using Lattice QCD simulations. We perform our calculations adopting an unphysically light weak boson mass of around $2\mathrm{GeV}$. We demonstrate that systematic errors for the Wilson coefficients $C_1$ and $C_2$, related to the current-current four-quark operators, can be controlled and present a path towards precise determinations in subsequent works.

    ↳ hep-lathep-phPRD(2018)·5 citations
21. 21*

    Cosmological magnetic fields in turbulent matter

    Maxim Dvornikov (IZMIRAN, Tomsk State University)🇷🇺

    We study the evolution of magnetic fields in turbulent hot plasma of the early Universe accounting for the chiral magnetic effect. The magnetohydrodynamic turbulence is modeled by replacing the matter velocity in the advection term in the Faraday equation with the Lorentz force. The system of the kinetic equations for the spectra of the densities of the magnetic helicity and the magnetic energy, as well as for the chiral imbalance, is derived. The amplification of the magnetic field is shown to result from the presence of the chiral magnetic effect solely. The system of the kinetic equations is solved numerically in primordial plasma after the electroweak phase transition. The influence of the matter turbulence on the magnetic field evolution is examined for different seed magnetic fields.

    ↳ astro-ph.COhep-phphysics.plasm-phJ.Phys.Conf.Ser.(2017)·0 citations
22. 22*

    $SU(2N_F)$ symmetry of confinement in QCD and its observation at high temperature

    L. Ya. Glozman🇦🇹

    In this talk we first overview lattice results that have led to the observation of new SU(2)_{CS} and SU(2N_F) symmetries upon artificial truncation of the near-zero modes of the Dirac operator at zero temperature and at high temperature without any truncation. These symmetries are larger than the chiral symmetry of the QCD Lagrangian and contain chiral symmetries SU(N_F)_L \times SU(N_F)_R and U(1)_A as subgroups. In addition to the standard chiral transformations the SU(2)_{CS} and SU(2N_F) transformations mix the right- and left-handed components of the quark fields. It is a symmetry of the confining chromo-electric interaction while the chromo-magnetic interaction manifestly breaks it. Emergence of these symmetries upon truncation of the near-zero modes of the Dirac operator at T=0 means that all effects of the chromo-magnetic interaction are located exclusively in the near-zero modes, while confining chromo-electric interaction is distributed among all modes. Appearance of these symmetries at high T, where the temperature suppresses the near-zero modes, has radical implications because these symmetries are incompatible with the asymptotically free deconfined quarks at increasing temperature. The elementary objects in the high-temperature phase of QCD should be quarks bound by the pure chromo-electric field that is not accompanied by the chromo-magnetic effects.

    ↳ hep-lathep-phhep-thnucl-thEPJ Web Conf.(2018)·2 citations
23. 23*

    Double inflation as a single origin of primordial black holes for all dark matter and LIGO observations

    Keisuke Inomata🇯🇵 · Masahiro Kawasaki🇯🇵 · Kyohei Mukaida🇩🇪 · Tsutomu T. Yanagida🇯🇵

    Primordial Black Hole (PBH) is one of the leading non-particle candidates for dark matter (DM). Although several observations severely constrain the amount of PBHs, it is recently pointed out that there is an uncertainty on the microlensing constraints below $\sim 10^{-10}{M}_{\odot }$ which was ignored originally but may weaken the constraints significantly. In this paper, facing this uncertainty, we investigate the possibility that PBHs can make up all DM in a broad mass spectrum. Moreover, we propose a concrete inflation model which can simultaneously produce PBHs for all DM in a broad mass spectrum around $\mathcal{O}(10^{-13})M_{\odot }$ and PBHs for LIGO events in a sharp mass spectrum at $\mathcal{O}(10)M_{\odot }$.

    ↳ astro-ph.COhep-phPRD(2018)·170 citations
24. 24*

    Holographic compact stars meet gravitational wave constraints

    Eemeli Annala🇫🇮 · Christian Ecker🇦🇹 · Carlos Hoyos🇪🇸 · Niko Jokela🇫🇮 · David Rodríguez Fernández🇪🇸 · Aleksi Vuorinen🇫🇮

    We investigate a simple holographic model for cold and dense deconfined QCD matter consisting of three quark flavors. Varying the single free parameter of the model and utilizing a Chiral Effective Theory equation of state (EoS) for nuclear matter, we find four different compact star solutions: traditional neutron stars, strange quark stars, as well as two non-standard solutions we refer to as hybrid stars of the second and third kind (HS2 and HS3). The HS2s are composed of a nuclear matter core and a crust made of stable strange quark matter, while the HS3s have both a quark mantle and a nuclear crust on top of a nuclear matter core. For all types of stars constructed, we determine not only their mass-radius relations, but also tidal deformabilities, Love numbers, as well as moments of inertia and the mass distribution. We find that there exists a range of parameter values in our model, for which the novel hybrid stars have properties in very good agreement with all existing bounds on the stationary properties of compact stars. In particular, the tidal deformabilities of these solutions are smaller than those of ordinary neutron stars of the same mass, implying that they provide an excellent fit to the recent gravitational wave data GW170817 of LIGO and Virgo. The assumptions underlying the viability of the different star types, in particular those corresponding to absolutely stable quark matter, are finally discussed at some length.

    ↳ astro-ph.HEgr-qchep-phhep-th+1JHEP(2018)·75 citations
25. 25*

    There is No Missing Satellites Problem

    Stacy Y. Kim🇺🇸 · Annika H. G. Peter🇺🇸 · Jonathan R. Hargis🇺🇸

    A critical challenge to the cold dark matter (CDM) paradigm is that there are fewer satellites observed around the Milky Way than found in simulations of dark matter substructure. We show that there is a match between the observed satellite counts corrected by the detection efficiency of the Sloan Digital Sky Survey (for luminosities $L\gtrsim$ 340 L${}_{\odot }$) and the number of luminous satellites predicted by CDM, assuming an empirical relation between stellar mass and halo mass. The "missing satellites problem", cast in terms of number counts, is thus solved. We also show that warm dark matter models with a thermal relic mass smaller than 4 keV are in tension with satellite counts, putting pressure on the sterile neutrino interpretation of recent X-ray observations. Importantly, the total number of Milky Way satellites depends sensitively on the spatial distribution of satellites, possibly leading to a "too many satellites" problem. Measurements of completely dark halos below $10^8$ M${}_{\odot }$, achievable with substructure lensing and stellar stream perturbations, are the next frontier for tests of CDM.

    ↳ astro-ph.COastro-ph.GAhep-phPRL(2018)·267 citations
26. 26*

    Brane-world extra dimensions in light of GW170817

    Luca Visinelli🇸🇪 · Nadia Bolis🇨🇿 · Sunny Vagnozzi🇸🇪

    The search for extra dimensions is a challenging endeavor to probe physics beyond the Standard Model. The joint detection of gravitational waves (GW) and electromagnetic (EM) signals from the merging of a binary system of compact objects like neutron stars (NS), can help constrain the geometry of extra dimensions beyond our 3+1 spacetime ones. A theoretically well-motivated possibility is that our observable Universe is a 3+1-dimensional hypersurface, or brane, embedded in a higher 4+1-dimensional Anti-de Sitter (AdS${}_5$) spacetime, in which gravity is the only force which propagates through the infinite bulk space, while other forces are confined to the brane. In these types of brane-world models, GW and EM signals between two points on the brane would, in general, travel different paths. This would result in a time-lag between the detection of GW and EM signals emitted simultaneously from the same source. We consider the recent near-simultaneous detection of the GW event GW170817 from the LIGO/Virgo collaboration, and its EM counterpart, the short gamma-ray burst GRB170817A detected by the Fermi Gamma-ray Burst Monitor and the INTEGRAL Anti-Coincidence Shield spectrometer. Assuming the standard $\Lambda$-Cold Dark Matter ($\Lambda$CDM) scenario and performing a likelihood analysis which takes into account astrophysical uncertainties associated to the measured time-lag, we set an upper limit of $\ell \lesssim 0.535$Mpc at $68\%$ confidence level on the AdS${}_5$ radius of curvature $\ell$. Although the bound is not competitive with current Solar System constraints, it is the first time that data from a multi-messenger GW-EM measurement is used to constrain extra-dimensional models. Thus, our work provides a proof-of-principle for the possibility of using multi-messenger astronomy for probing the geometry of our space-time.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2018)·165 citations
27. 27*

    Laminar and turbulent dynamos in chiral magnetohydrodynamics. II. Simulations

    Jennifer Schober🇸🇪 · Igor Rogachevskii🇮🇱 · Axel Brandenburg🇺🇸 · Alexey Boyarsky🇳🇱 · Juerg Froehlich🇨🇭 · Oleg Ruchayskiy🇩🇰 · Nathan Kleeorin🇮🇱

    Using direct numerical simulations (DNS), we study laminar and turbulent dynamos in chiral magnetohydrodynamics (MHD) with an extended set of equations that accounts for an additional contribution to the electric current due to the chiral magnetic effect (CME). This quantum phenomenon originates from an asymmetry between left- and right-handed relativistic fermions in the presence of a magnetic field and gives rise to a chiral dynamo. We show that the magnetic field evolution proceeds in three stages: (1) a small-scale chiral dynamo instability; (2) production of chiral magnetically driven turbulence and excitation of a large-scale dynamo instability due to a new chiral effect (alpha_mu effect); and (3) saturation of magnetic helicity and magnetic field growth controlled by a conservation law for the total chirality. The ${\alpha }_{\mu }$ effect becomes dominant at large fluid and magnetic Reynolds numbers and is not related to kinetic helicity. The growth rate of the large-scale magnetic field and its characteristic scale measured in the numerical simulations agree well with theoretical predictions based on mean-field theory. The previously discussed two-stage chiral magnetic scenario did not include stage (2) during which the characteristic scale of magnetic field variations can increase by many orders of magnitude. Based on the findings from numerical simulations, the relevance of the CME and the chiral effects revealed in the relativistic plasma of the early universe and of proto-neutron stars are discussed.

    ↳ physics.flu-dynastro-ph.COastro-ph.HEhep-ph+1ApJ(2018)·72 citations

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