Fri·Aug 23, 2019Friday·August 23, 2019

1. 01*

   The phase diagram of the Polyakov Nambu Jona-Lasinio approach for finite chemical potentials

   David Fuseau🇫🇷 · Thorsten Steinert🇩🇪 · Joerg Aichelin🇫🇷

   We extend the SU(3) (Polyakov) Nambu Jona-Lasinio in two ways: We introduce the next to leading order contribution (in $N_c$) in the partition function. This contribution contains explicit mesonic terms. We introduce a coupling between the gluon field and the quark degrees of freedom which goes beyond a simple rescaling of the critical temperature. With both these improvements we can reproduce, for vanishing chemical potentials, the lattice results for the thermal properties of a strongly interacting system like pressure, energy density, entropy density, interaction measure and the speed of sound. Also the expansion parameter towards small but finite chemical potentials agrees with the lattice results. Extending the calculations to finite chemical potentials (what does not require any new parameter) we find a first order phase transition up to a critical end point of $T_{CEP}=110MeV$ and ${\mu }_q=320MeV$. For very large chemical potentials, we find agreement with pQCD calculations. We calculate the mass of mesons and baryons as a function of temperature and chemical potential and the transition between the hadronic and the chirally restored phase. These calculations provide an equation of state in the whole $T,\mu$ plane an essential ingredient for dynamical calculations of ultra-relativistic heavy ion collisions but also for the physics of neutron stars and neutron star collisions.

   hep-phhep-thPRC(2020)·18 citations
2. 02*

   Flavoured leptogenesis and ${\mathrm{CP}}^{\mu \tau }$ symmetry

   Rome Samanta🇬🇧 · Manibrata Sen🇺🇸

   We present a systematic study of leptogenesis in neutrino mass models with $\mu \tau$-flavoured CP symmetry. In addition to the strong hierarchical $N_1$-dominated scenario ($N_1$DS) in the `two flavour regime' of leptogenesis, we show that one may choose the right-handed (RH) neutrino mass hierarchy as mild as $M_2\simeq 4.7M_1$ for a perfectly valid hierarchical $N_1$DS. This in turn reduces the lower bound on the allowed values of $M_1$, compared to what is stated in the literature. The consideration of flavour effects due to the heavy neutrinos also translate into an upper bound on $M_1$. It is only below this bound that the observed baryon-to-photon ratio can be realized for a standard $N_1$ domination, else a substantial part of the parameter space is also compatible with $N_2$DS. We deduce conditions under which the baryon asymmetry produced by the second RH neutrino plays an important role. Finally, we discuss another interesting scenario where lepton asymmetry generated by $N_2$ in the two flavour regime faces washout by $N_1$ in the three flavour regime. Considering a hierarchical light neutrino mass spectrum, which is now favoured by cosmological observations, we show that at the end of $N_1$-leptogenesis, the asymmetry generated by $N_2$ survives only in the electron flavour and around $33\%$ of the parameter space is consistent with a pure $N_2$-leptogenesis.

   hep-phJHEP(2020)·16 citations
3. 03*

   Boosted $W/Z$ Tagging with Jet Charge and Deep Learning

   Yu-Chen Janice Chen🇹🇼 · Cheng-Wei Chiang🇹🇼 · Giovanna Cottin🇹🇼 · David Shih🇺🇸

   We demonstrate that the classification of boosted, hadronically-decaying weak gauge bosons can be significantly improved over traditional cut-based and BDT-based methods using deep learning and the jet charge variable. We construct binary taggers for $W^{+}$ vs. $W^{-}$ and $Z$ vs. $W$ discrimination, as well as an overall ternary classifier for $W^{+}$/$W^{-}$/$Z$ discrimination. Besides a simple convolutional neural network (CNN), we also explore a composite of two CNNs, with different numbers of layers in the jet $p_T$ and jet charge channels. We find that this novel structure boosts the performance particularly when considering the $Z$ boson as signal. The methods presented here can enhance the physics potential in SM measurements and searches for new physics that are sensitive to the electric charge of weak gauge bosons.

   hep-phhep-exPRD(2020)·51 citations
4. 04*

   Electroweak-QCD interference in hadronic vector bosons at LHC

   Cathy Ding · Ben Fuller · Eleanor Jones🇬🇧 · Aran Martin · William Murray🇬🇧

   The analysis of hadronic vector boson decays at LHC does not normally allow for interference with QCD production. These effects are studied here using the Sherpa package and can move by several GeV/c 2 the peak positions experiments would reconstruct. However, their impact depends strongly on the kinematics involved. The shifts expected in boosted W and Z bosons, which have been the subject of experimental study, are explored for the first time. The effects in the channels examined are all very small or negligible, but this may not true if lower transverse momenta are analysed, for example in the experimental trigger systems.

   hep-phEPJC(2020)·4 citations
5. 05*

   Intrinsic three-body nuclear interaction from a constituent quark model

   Aaron Park🇰🇷 · Su Houng Lee🇰🇷

   We study the short distance part of the intrinsic three-nucleon interaction in a constituent quark model with color-spin interaction. For that purpose we first calculate the transformation coefficient between the tribaryon configuration and their corresponding three baryon basis. Using a formula for the intrinsic three-body interaction in terms of a tribaryon configuration, we find that after subtracting the corresponding two-baryon contributions, the intrinsic three-body interaction vanishes in flavor SU(3) symmetric limit for all quantum numbers for the three nucleon states. We further find that the intrinsic three-body interaction also vanishes for flavor-spin type of quark interaction.

   hep-phnucl-thPRC(2019)·6 citations
6. 06*

   CIMBA: fast Monte Carlo generation using cubic interpolation

   Philip Ilten🇬🇧

   Monte Carlo generation of high energy particle collisions is a critical tool for both theoretical and experimental particle physics, connecting perturbative calculations to phenomenological models, and theory predictions to full detector simulation. The generation of minimum bias events can be particularly computationally expensive, where non-perturbative effects play an important role and specific processes and fiducial regions can no longer be well defined. In particular scenarios, particle guns can be used to quickly sample kinematics for single particles produced in minimum bias events. CIMBA (Cubic Interpolation for Minimum Bias Approximation) provides a comprehensive package to smoothly sample predefined kinematic grids, from any general purpose Monte Carlo generator, for all particles produced in minimum bias events. These grids are provided for a number of beam configurations including those of the Large Hadron Collider.

   hep-phhep-exComput.Phys.Commun.(2021)·4 citations
7. 07*

   Towards the meV limit of the effective neutrino mass in neutrinoless double-beta decays

   Jun Cao🇨🇳 · Guo-yuan Huang🇨🇳 · Yu-Feng Li🇨🇳 · Yifang Wang🇨🇳 · Liang-Jian Wen🇨🇳 · Zhi-zhong Xing🇨🇳 · Zhen-hua Zhao🇨🇳 · Shun Zhou🇨🇳

   In this paper, we emphasize why it is important for future neutrinoless double-beta ($0\nu \beta \beta$) decay experiments to reach the sensitivity to the effective neutrino mass $|m_{\beta \beta }^{}|\approx 1\mathrm{meV}$. Assuming such a sensitivity and the precisions on neutrino oscillation parameters after the JUNO experiment, we fully explore the constrained regions of the lightest neutrino mass $m_1^{}$ and two Majorana-type CP-violating phases $\{\rho ,\sigma \}$. The implications for the neutrino mass spectrum, the effective neutrino mass $m_{\beta }^{}$ in beta decays and the sum of three neutrino masses $\Sigma \equiv m_1^{}+m_2^{}+m_3^{}$ relevant for cosmological observations are also discussed.

   hep-phhep-exCPC(2020)·53 citations
8. 08*

   Renormalization group improved pressure for cold and dense QCD

   Jean-Loïc Kneur🇫🇷 · Marcus Benghi Pinto🇧🇷 · Tulio Eduardo Restrepo🇧🇷

   We apply the renormalization group optimized perturbation theory (RGOPT)to evaluate the QCD (matter) pressure at the two-loop level considering three flavors of massless quarks in a dense and cold medium. Already at leading order (${\alpha }_s^0$), which builds on the simple one loop (RG resummed) term, our technique provides a non-trivial non-perturbative approximation which is completely renormalization group invariant. At the next-to-leading order the comparison between the RGOPT and the pQCD predictions shows that the former method provides results which are in better agreement with the state-of-the-art $higherorder$ perturbative results, which include a contribution of order ${\alpha }_s^3{\ln }^2{\alpha }_s$. At the same time one also observes that the RGOPT predictions are less sensitive to variations of the arbitrary $\overline{\mathrm{MS}}$ renormalization scale than those obtained with pQCD. These results indicate that the RGOPT provides an efficient resummation scheme which may be considered as an alternative to lattice simulations at high baryonic densities.

   hep-phhep-thnucl-thPRD(2019)·20 citations
9. 09*

   How to include exclusive $J/\psi$ production data in global PDF analyses

   Chris A. Flett🇬🇧 · Stephen P. Jones🇨🇭 · Alan D. Martin🇬🇧 · Misha G. Ryskin🇬🇧 · Thomas Teubner🇬🇧

   We compare the cross section for exclusive $J/\psi$ photoproduction calculated at NLO in the collinear factorization approach with HERA and LHCb data. Using the optimum scale formalism together with the subtraction of the low $k_t<Q_0$ contribution from the NLO coefficient function to avoid double counting we show that the existing global parton distribution functions (PDFs) are consistent with the data within their uncertainties. However, at low $x$ the uncertainties of the present global PDFs are large. On the other hand, the accuracy of the LHCb data are rather good. Therefore, these data provide the possibility to directly measure the gluon PDF over the very large interval of $x$, $10^{-6}<x<10^{-2}$, at a fixed low scale.

   hep-phPRD(2020)·47 citations
10. 10*

    Phenomenology of $keV$ sterile neutrino in minimal extended seesaw

    Pritam Das🇮🇳 · Mrinal Kumar Das🇮🇳

    We explore the possibility of a single generation of $keV$ scale sterile neutrino ($m_S$) as a dark matter candidate within the minimal extended seesaw (MES) framework and it's influence in neutrinoless double beta decay ($0\nu \beta \beta$) study. Three hierarchical right-handed neutrinos were considered to explain neutrino mass. We also address baryogenesis via the mechanism of thermal leptogenesis considering the decay of the lightest RH neutrino to a lepton and Higgs doublet. A generic model based on $A_4\times Z_4\times Z_3$ flavor symmetry is constructed to explain both normal and inverted hierarchy mass pattern of neutrinos. Significant results on effective neutrino masses are observed in presence of sterile mass ($m_S$) and active-sterile mixing (${\theta }_S$) in $0\nu \beta \beta$. Results from $0\nu \beta \beta$ give stringent upper bounds on the active-sterile mixing matrix element. To establish sterile neutrino as dark matter within this model, we checked decay width and relic abundance of the sterile neutrino, which restricted sterile mass ($m_S$) within some definite bounds. Constrained regions on the CP-phases and Yukawa couplings are obtained from $0\nu \beta \beta$ and baryogenesis results. Co-relations among these observable are also established and discussed within this framework.

    hep-phInt.J.Mod.Phys.A(2020)·10 citations
11. 11*

    Nucleon-antinucleon annihilation at LEAR

    Claude Amsler🇦🇹

    This report is a historical review of the salient results in low energy antiproton-proton and antineutron-proton annihilation obtained at the Low Energy Antiproton Ring (LEAR), which was operated at CERN between 1983 and 1996. The intention is to provide guidelines for future experiments at the CERN AD/ELENA complex and elsewhere. In the spirit of this workshop, hadron spectroscopy - one of the cornerstones at LEAR - is briefly mentioned, while emphasis is put on the annihilation mechanism on one and two nucleons, the final state multiplicity distributions and the contributions from quarks, in particular in annihilation channels involving strangeness.

    hep-phnucl-exnucl-th17 citations
12. 12*

    Dynamical resolution scale in transverse momentum distributions at the LHC

    F. Hautmann🇧🇪 · L. Keersmaekers🇧🇪 · A. Lelek🇧🇪 · A. M. van Kampen🇧🇪

    The QCD evolution of transverse momentum dependent (TMD) distribution functions has recently been formulated in a parton branching (PB) formalism. In this approach, soft-gluon coherence effects are taken into account by introducing the soft-gluon resolution scale and exploiting the relation between transverse-momentum recoils and branching scales. In this work we investigate the implications of dynamical, i.e., branching scale dependent, resolution scales. We present both analytical studies and numerical solution of PB evolution equations in the presence of dynamical resolution scales. We use this to compare PB results with other approaches in the literature, and to analyze predictions for transverse momentum distributions in $Z$-boson production at the Large Hadron Collider (LHC).

    hep-phNPB(2019)·69 citations
13. 13*

    Hydro+ in Action: Understanding the Out-of-Equilibrium Dynamics Near a Critical Point in the QCD Phase Diagram

    Krishna Rajagopal🇺🇸 · Gregory Ridgway🇺🇸 · Ryan Weller🇺🇸 · Yi Yin🇺🇸

    Upcoming experimental programs will look for signatures of a possible critical point in the QCD phase diagram in fluctuation observables. To understand and predict these signatures, one must account for the fact that the dynamics of any critical fluctuations must be out-of-equilibrium: because of critical slowing down, the fluctuations cannot stay in equilibrium as the droplet of QGP produced in a collision expands and cools. Furthermore, their out-of-equilibrium dynamics must also influence the hydrodynamic evolution of the cooling droplet. The recently developed Hydro+ formalism allows for a consistent description of both the hydrodynamics and the out-of-equilibrium fluctuations, including the feedback between them. We shall explicitly demonstrate how this works, setting up a Hydro+ simulation in a simplified setting: a rapidity-independent fireball undergoing radial flow with an equation of state in which we imagine a critical point close to the ${\mu }_B=0$ axis of the phase diagram. Within this setup, we show that we can quantitatively capture non-equilibrium phenomena, including critical fluctuations over a range of scales and memory effects. Furthermore, we illustrate the interplay between the dynamics of the fluctuations and the hydrodynamic flow of the fireball: as the fluid cools and flows, the dynamical fluctuations lag relative to how they would evolve if they stayed in equilibrium; there is then a backreaction on the flow itself due to the out-of-equilibrium fluctuations; and, in addition, the radial flow transports fluctuations outwards by advection. Within our model, we find that the backreaction from the out-of-equilibrium fluctuations does not yield dramatically large effects in the hydrodynamic variables. Further work will be needed in order to check this quantitative conclusion in other settings but, if it persists, this will considerably simplify future modelling.

    hep-phnucl-thPRD(2020)·81 citations
14. 14*

    Exploring the Space of Jets with CMS Open Data

    Patrick T. Komiske🇺🇸 · Radha Mastandrea🇺🇸 · Eric M. Metodiev🇺🇸 · Preksha Naik🇺🇸 · Jesse Thaler🇺🇸

    We explore the metric space of jets using public collider data from the CMS experiment. Starting from 2.3/fb of 7 TeV proton-proton collisions collected at the Large Hadron Collider in 2011, we isolate a sample of 1,690,984 central jets with transverse momentum above 375 GeV. To validate the performance of the CMS detector in reconstructing the energy flow of jets, we compare the CMS Open Data to corresponding simulated data samples for a variety of jet kinematic and substructure observables. Even without detector unfolding, we find very good agreement for track-based observables after using charged hadron subtraction to mitigate the impact of pileup. We perform a range of novel analyses, using the "energy mover's distance" (EMD) to measure the pairwise difference between jet energy flows. The EMD allows us to quantify the impact of detector effects, visualize the metric space of jets, extract correlation dimensions, and identify the most and least typical jet configurations. To facilitate future jet studies with CMS Open Data, we make our datasets and analysis code available, amounting to around two gigabytes of distilled data and one hundred gigabytes of simulation files.

    hep-phhep-exPRD(2020)·68 citations
15. 15*

    Fully-heavy tetraquarks: $bb\bar{c}\bar{c}$ and $bc\bar{b}\bar{c}$

    Xiaoyun Chen🇨🇳

    In the framework of a nonrelativistic chiral quark model, we continue to study the mass spectra of the fully-heavy $bb\bar{c}\bar{c}$ and $bc\bar{b}\bar{c}$ tetraquarks. In the present calculations, two structures, meson-meson [$\bar{Q}Q$][$\bar{Q}Q$] and diquark-antidiquark [$QQ$][$\bar{Q}\bar{Q}$] ($Q$ = $c$ or $b$), and their mixing, along with all possible color, spin configurations are considered. The calculations suggest that no bound state can be formed for $bb\bar{c}\bar{c}$ and $bc\bar{b}\bar{c}$ systems. However, resonances are possible because of the color structure. Several resonances are predicted and their stabilities are checked using the real scaling method.

    hep-phPRD(2019)·30 citations
16. 16*

    Propagation of particles on a torus

    Peng Guo🇺🇸

    In this study, based on the variational principle and Faddeev method, we present a general framework for finding the propagating solutions of multiple interacting particles on a torus. Two different versions of multiparticle secular equations are presented. Version one shows how the propagating solutions on a torus and the infinite volume dynamics are connected. The second version may be more suitable and robust for the task of lattice quantum chromodynamics data analysis. The proposed formalism may also be useful for studying the effects of few-body interactions on the electronic band structure in condensed matter physics.

    ↳ hep-latcond-mat.str-elhep-phPLB(2020)·31 citations
17. 17*

    X-ray Intra-day Variability of the TeV Blazar Mrk 421 with Suzaku

    Zhongli Zhang🇨🇳 · Alok C. Gupta🇮🇳 · Haritma Gaur🇮🇳 · Paul J. Wiita🇺🇸 · Tao An🇨🇳 · Minfeng Gu🇨🇳 · Dan Hu🇨🇳 · Haiguang Xu🇨🇳

    We present X-ray flux and spectral analyses of the three pointed Suzaku observations of the TeV high synchrotron peak blazar Mrk 421 taken throughout its complete operational duration. The observation taken on 5 May 2008 is, at 364.6 kiloseconds (i.e., 101.3 hours), the longest and most evenly sampled continuous observation of this source, or any blazar, in the X-ray energy 0.8 - 60 keV until now. We found large amplitude intra-day variability in all soft and hard bands in all the light curves. The discrete correction function analysis of the light curves in soft and hard bands peaks on zero lag, showing that the emission in hard and soft bands are cospatial and emitted from the same population of leptons. The hardness ratio plots imply that the source is more variable in the harder bands compared to the softer bands. The source is harder-when-brighter, following the general behavior of high synchrotron peak blazars. Power spectral densities of all three light curves are red noise dominated, with a range of power spectra slopes. If one assumes that the emission originates very close to the central super massive black hole, a crude estimate for its mass, of ~ 4 * 10^{8} M_{\odot}, can be made; but if the variability is due to perturbations arising there that are advected into the jet and are thus Doppler boosted, substantially higher masses are consistent with the quickest seen variations. We briefly discuss the possible physical mechanisms most likely responsible for the observed flux and spectral variability.

    ↳ astro-ph.HEhep-ph19 citations
18. 18*

    Electron-positron pair production in frequency modulated laser fields

    C. Gong🇨🇳 · Z. L. Li🇨🇳 · B. S. Xie🇨🇳 · Y. J. Li🇨🇳

    The momentum spectrum and the number density of created electron-positron pairs in a frequency modulated laser field are investigated using quantum kinetic equation. It is found that the momentum spectrum presents obvious interference pattern. This is an imprint of the frequency modulated field on the momentum spectrum, because the momentum peaks correspond to the pair production process by absorbing different frequency component photons. Moreover, the interference effect can also be understood qualitatively by analyzing turning point structures. The study of the pair number density shows that the number density is very sensitive to modulation parameters and can be enhanced by over two orders of magnitude for certain modulation parameters, which may provide a new way to increase the number of created electron-positron pairs in future experiments.

    ↳ quant-phhep-phPRD(2020)·31 citations
19. 19*

    Dark matter searches with the IceCube Upgrade

    Sebastian Baur (for the IceCube Collaboration)🇧🇪

    Weakly Interacting Massive Particles (WIMPs) are well-motivated candidates for Dark Matter (DM). WIMP models often include self-annihilation into Standard Model particles such as neutrinos which could potentially be detected by the IceCube Neutrino Observatory. Various searches for a dark matter induced signal have been performed with the existing IceCube detector. However, since there is so far no evidence for WIMPs at TeV scales, more attention is brought to DM candidates at GeV masses, for which the IceCube detector is not sensitive due to its energy threshold. The IceCube collaboration is currently preparing the construction of the IceCube Upgrade which is planned to be deployed in the 2022/2023 South Pole summer season. The IceCube Upgrade will consist of 7 new in-ice strings with about 700 additional optical sensors. This dense sensor array inside the IceCube-DeepCore volume will enhance the reconstruction capability of few-GeV neutrinos. We present first studies on the potential improvements of this upgrade on IceCube's sensitivity to Dark Matter annihilating in the Galactic Center.

    ↳ astro-ph.HEhep-phPoS(2020)·20 citations
20. 20*

    A generator of forward neutrons for ultra-peripheral collisions: \textbf{n\mathbf{_O^O}n}

    M. Broz🇨🇿 · J. G. Contreras🇨🇿 · J. D. Tapia Takaki🇺🇸

    The study of photon-induced reactions in collisions of heavy nuclei at RHIC and the LHC has become an important direction of the research program of these facilities in recent years. In particular, the production of vector mesons in ultra-peripheral collisions (UPC) has been intensively studied. Owing to the intense photon fluxes, the two nuclei participating in such processes undergo electromagnetic dissociation producing neutrons at beam rapidities. Here, we introduce the \textbf{n\mathbf{_O^O}n} (pronounced noon) Monte Carlo program, which generates events containing such neutrons. \textbf{n\mathbf{_O^O}n} is a ROOT based program that can be interfaced with existing generators of vector meson production in UPC or with theoretical calculations of such photonuclear processes. \textbf{n\mathbf{_O^O}n} can also be easily integrated with the simulation programs of the experiments at RHIC and the LHC.

    ↳ nucl-thhep-phComput.Phys.Commun.(2020)·60 citations
21. 21*

    Multi-messenger tests of cosmic-ray acceleration in radiatively inefficient accretion flows

    Shigeo S. Kimura🇺🇸 · Kohta Murase🇺🇸 · Peter Mészáros🇺🇸

    The cores of active galactic nuclei (AGNs) have been suggested as the sources of IceCube neutrinos, and recent numerical simulations have indicated that hot AGN coronae of Seyfert galaxies and radiatively inefficient accretion flows (RIAFs) of low-luminosity AGNs (LLAGNs) may be promising sites of ion acceleration. We present detailed studies on detection prospects of high-energy multi-messenger emissions from RIAFs in nearby LLAGNs. We construct a model of RIAFs that can reproduce the observational features of the current X-ray observations of nearby LLAGNs. We then calculate the high-energy particle emissions from nearby individual LLAGNs, including MeV gamma rays from thermal electrons, TeV--PeV neutrinos produced by non-thermal protons, and sub-GeV to sub-TeV gamma rays from proton-induced electromagnetic cascades. We find that, although these are beyond the reach of current facilities, proposed future experiments such as e-ASTROGAM and IceCube-Gen2 should be able to detect the MeV gamma rays and the neutrinos, respectively, or else they can place meaningful constraints on the parameter space of the model. On the other hand, the detection of high-energy gamma rays due to the electromagnetic cascades will be challenging with the current and near-future experiments, such as Fermi and Cherenkov Telescope Array. In an accompanying paper, we demonstrate that LLAGNs can be a source of the diffuse soft gamma-ray and TeV--PeV neutrino backgrounds, whereas in the present paper, we focus on the prospects for multi-messenger tests which can be applied to reveal the nature of the high-energy neutrinos and photons from LLAGNs.

    ↳ astro-ph.HEhep-phPRD(2019)·44 citations
22. 22*

    Thermal Broadening of Bottomonia: Lattice Non-Relativistic QCD with Extended Operators

    Rasmus Larsen🇺🇸 · Stefan Meinel🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸

    We present lattice non-relativistic QCD calculations of bottomonium correlation functions at temperatures $T\simeq 150-350$ MeV. The correlation functions were computed using extended bottomonium operators, and on background gauge-field configurations for 2+1-flavor QCD having physical kaon and nearly-physical pion masses. We analyzed these correlation functions based on simple theoretically-motivated parameterizations of the corresponding spectral functions. The results of our analyses are compatible with significant in-medium thermal broadening of the ground state S- and P-wave bottomonia.

    ↳ hep-lathep-phnucl-thPRD(2019)·69 citations
23. 23*

    Using SPTpol, Planck 2015, and non-CMB data to constrain tilted spatially-flat and untilted non-flat $\Lambda$CDM, XCDM, and $\varphi$CDM dark energy inflation cosmologies

    Chan-Gyung Park🇰🇷 · Bharat Ratra🇺🇸

    We use six tilted spatially-flat and untilted non-flat dark energy cosmological models in analyses of South Pole Telescope polarization (SPTpol) cosmic microwave background (CMB) data, alone and in combination with Planck 2015 CMB data and non-CMB data, namely, the Pantheon Type Ia supernovae apparent magnitudes, a collection of baryon acoustic oscillation data points, Hubble parameter measurements, and growth rates. Although the cosmological models that best-fit the Planck CMB and non-CMB data do not provide good fits to the SPTpol data, with the ${\chi }^2$'s exceeding the expected value, given the uncertainties, in each model the cosmological parameter constraints from the SPTpol data and from the Planck CMB and non-CMB data are largely mutually consistent. When the smaller angular scale SPTpol data are used jointly with either the Planck data alone or with the Planck CMB and the non-CMB data to constrain untilted non-flat models, spatially-closed models remain favored over their corresponding flat limits. When used in conjunction with Planck data, non-CMB data (baryon acoustic oscillation measurements in particular, from six experiments) have significantly more constraining power than the SPTpol data.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2020)·80 citations
24. 24*

    Fractals, non-extensive statistics and QCD

    Airton Deppman🇧🇷 · Eugenio Megias🇪🇸 · Debora P. Menezes🇧🇷

    In this work we analyse how scaling properties of Yang-Mills field theory manifest as self-similarity of truncated n-point functions by scale evolution. The presence of such structures, which actually behaves as fractals, allow for recurrent non-perturbative calculation of any vertex. Some general properties are indeed independent of the perturbative order, what simplifies the non-perturbative calculations. We show that for sufficiently high perturbative orders a statistical approach can be used, the non extensive statistics is obtained, and the Tsallis index, $q$, is deduced in terms of the field theory parameters. The results are applied to QCD in the one-loop approximation, where $q$ can be calculated, resulting in a good agreement with the value obtained experimentally. We discuss how this approach allows to understand some intriguing experimental findings in high energy collisions, as the behavior of multiplicity against collision energy, long-tail distributions and the fractal dimension observed in intermittency analysis.

    ↳ hep-thhep-phnucl-thPRD(2020)·49 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.