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Nuclear Theory·nucl-th

Thursday·January 21, 2016

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 08

    Factorization and Resummation for Generic Hierarchies between Jets

    Piotr Pietrulewicz🇩🇪 · Frank J. Tackmann🇩🇪 · Wouter J. Waalewijn🇳🇱

    Jets are an important probe to identify the hard interaction of interest at the LHC. They are routinely used in Standard Model precision measurements as well as in searches for new heavy particles, including jet substructure methods. In processes with several jets, one typically encounters hierarchies in the jet transverse momenta and/or dijet invariant masses. Large logarithms of the ratios of these kinematic jet scales in the cross section are at present primarily described by parton showers. We present a general factorization framework called SCET, which is an extension of Soft-Collinear Effective Theory (SCET) and allows for a systematic higher-order resummation of such kinematic logarithms for generic jet hierarchies. In SCET additional intermediate soft/collinear modes are used to resolve jets arising from additional soft and/or collinear QCD emissions. The resulting factorized cross sections utilize collinear splitting amplitudes and soft gluon currents and fully capture spin and color correlations. We discuss how to systematically combine the different kinematic regimes to obtain a complete description of the jet phase space. To present its application in a simple context, we use the case of 3 jets. We then discuss in detail the application to N-jet processes at hadron colliders, considering representative classes of hierarchies from which the general case can be built. This includes in particular multiple hierarchies that are either strongly ordered in angle or energy or not.

    ↳ hep-phnucl-thJHEP(2016)·49 citations
  2. 09

    Bottomonium spectrum revisited

    Jorge Segovia🇩🇪 · Pablo G. Ortega🇨🇭 · David R. Entem🇪🇸 · Francisco Fernández🇪🇸

    We revisit the bottomonium spectrum motivated by the recently exciting experimental progress in the observation of new bottomonium states, both conventional and unconventional. Our framework is a nonrelativistic constituent quark model which has been applied to a wide range of hadronic observables from the light to the heavy quark sector and thus the model parameters are completely constrained. Beyond the spectrum, we provide a large number of electromagnetic, strong and hadronic decays in order to discuss the quark content of the bottomonium states and give more insights about the better way to determine their properties experimentally.

    ↳ hep-phhep-exhep-latnucl-thPRD(2016)·151 citations
  3. 10

    Glueball dynamics in the hot plasma

    Nikolai Kochelev🇷🇺

    We discuss the glueball contribution to the equation of state (EoS) of hot gluon matter below and above . It is shown that the strong changing of masses of scalar and pseudoscalar glueballs near plays very important role in the thermodynamics of gauge theory. In particular, we give the arguments that these glueballs become massless at and this phenomenon is crucial in understanding of the mystery in the behavior of trace anomaly founded in the lattice calculation.

    ↳ hep-phhep-exnucl-exnucl-thEPJA(2016)·1 citation
  4. 11

    Indication of a Differential Freeze-out in Proton-Proton and Heavy-Ion Collisions at RHIC and LHC energies

    Dhananjaya Thakur🇮🇳 · Sushanta Tripathy🇮🇳 · Prakhar Garg🇮🇳 · Raghunath Sahoo🇮🇳 · Jean Cleymans🇿🇦

    The experimental data from the RHIC and LHC experiments of invariant pT spectra in A+A and p + p collisions are analysed with Tsallis distributions in different approaches. The information about the freeze-out surface in terms of freeze-out volume, temperature, chemical potential and radial flow velocity for different particle species are obtained. Further, these parameters are studied as a function of the mass of the secondary particles. A mass-dependent differential freeze-out is observed which does not seem to distinguish between particles and their antiparticles. Further a mass-hierarchy in the radial flow is observed, meaning heavier particles suffer lower radial flow. Tsallis distribution function at finite chemical potential is used to study the mass dependence of chemical potential. The peripheral heavy-ion and proton-proton collisions at the same energies seem to be equivalent in terms of the extracted thermodynamic parameters.

    ↳ hep-phnucl-exnucl-thAdv.High Energy Phys.(2016)·75 citations
  5. 12

    Rotating neutron stars with exotic cores: masses, radii, stability

    P. Haensel🇵🇱 · M. Bejger🇵🇱 · M. Fortin🇵🇱 · J.L. Zdunik🇵🇱

    A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation frequency (716 Hz) and the maximum measured mass (). Present status of measuring the radii of neutron stars is described. The theory of rigidly rotating stars in general relativity is reviewed and limitations of the slow rotation approximation are pointed out. Mass-radius relations for rotating neutron stars with hyperon and quark cores are illustrated using several models. Problems related to the non-uniqueness of the crust-core matching are mentioned. Limits on rigid rotation resulting from the mass-shedding instability and the instability with respect to the axisymmetric perturbations are summarized. The problem of instabilities and of the back-bending phenomenon are discussed in detail. Metastability and instability of a neutron star core in the case of a first-order phase transition, both between pure phases, and into a mixed-phase state, are reviewed. The case of two disjoint families (branches) of rotating neutron stars is discussed and generic features of neutron-star families and of core-quakes triggered by the instabilities are considered.

    ↳ astro-ph.HEastro-ph.SRnucl-thEPJA(2016)·53 citations

Affiliations

first authorsco-authorsvia INSPIRE