Nuclear Theory·nucl-th

Wednesday·September 20, 2017

6 papers—1 primary·5 cross-listed

02
[Submitted on 18 Sept 2017] (cross-list from hep-ph)
Spectroscopy of Exotic Hadrons Formed from Dynamical Diquarks
Richard F. Lebed🇺🇸
The dynamical diquark picture asserts that exotic hadrons can be formed from widely separated colored diquark or triquark components. We use the Born-Oppenheimer (BO) approximation to study the spectrum of states thus constructed, both in the basis of diquark spins and in the basis of heavy quark-antiquark spins. We develop a compact notation for naming these states, and use the results of lattice simulations for hybrid mesons to predict the lowest expected BO potentials for both tetraquarks and pentaquarks. We then compare to the set of exotic candidates with experimentally determined quantum numbers, and find that all of them can be accommodated. Once decay modes are also considered, one can develop selection rules of both exact ( $J^{P C}$ conservation) and approximate (within the context of the BO approximation) types and test their effectiveness. We find that the most appealing way to satisfy both sets of selection rules requires including additional low-lying BO potentials, a hypothesis that can be checked on the lattice.
Comments:
14 pages. Version accepted for publication in Phys. Rev D. Includes a new section discussing alternate multiquark approaches
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1709.06097 [pdf]
PRD(2017)·50 citations
03
[Submitted on 19 Sept 2017] (cross-list from hep-ph)
Dissipative Properties and Isothermal Compressibility of Hot and Dense Hadron Gas using Non-extensive Statistics
Swatantra Kumar Tiwari🇮🇳 · Sushanta Tripathy🇮🇳 · Raghunath Sahoo🇮🇳 · Nilotpal Kakati🇮🇳
We evaluate the transport properties such as shear viscosity ( $η$ ), bulk viscosity ( $ζ$ ) and their ratios over entropy density ( $s$ ) for hadronic matter using relativistic non-extensive Boltzmann transport equation (NBTE) in relaxation time approximation (RTA). In NBTE, we argue that the system far from equilibrium may not reach to an equilibrium described by extensive (Boltzmann-Gibbs (BG)) statistics but to a $q$ -equilibrium defined by Tsallis non-extensive statistics after subsequent evolution, where $q$ denotes the degree of non-extensivity. We observe that $η / s$ and $ζ / s$ decrease rapidly with temperature ( $T$ ) for various $q$ -values. As $q$ increases, the magnitudes of $η / s$ and $ζ / s$ decrease with $T$ . We also show the upper mass cutoff dependence of these ratios for a particular $q$ and find that they decrease with the increase in mass cutoff of hadrons. Further, we present the first estimation of isothermal compressibility ( $κ_{T}$ ) using non-extensive Tsallis statistics at finite baryon chemical potential ( $μ_{B}$ ). It is observed that, $κ_{T}$ changes significantly with the degree of non-extensivity. We also study the squared speed of sound ( $c_{s}^{2}$ ) as a function of temperature at finite baryon chemical potential for various $q$ and upper mass cutoffs. It is noticed that there is a strong impact of $q$ and mass cutoff on the behaviour of $c_{s}^{2}$ .
Comments:
Same as published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1709.06352 [pdf]
EPJC(2018)·17 citations
04
[Submitted on 19 Sept 2017] (cross-list from hep-ph)
Elliptic Flow in Pb+Pb Collisions at $s_{NN}$ = 2.76 TeV at the LHC Using Boltzmann Transport Equation with Non-extensive Statistics
Sushanta Tripathy🇮🇳 · Swatantra Kumar Tiwari🇮🇳 · Mohammed Younus🇮🇳 · Raghunath Sahoo🇮🇳
Elliptic flow in heavy-ion collisions is an important signature of a possible de-confinement transition from hadronic phase to partonic phase. In the present work, we use non-extensive statistics, which has been used for transverse momentum ( $p_{T}$ ) distribution in proton+proton ( $p + p$ ) collisions, as the initial particle distribution function in Boltzmann Transport Equation (BTE). A Boltzmann-Gibbs Blast Wave (BGBW) function is taken as an equilibrium function to get the final distribution to describe the particle production in heavy-ion collisions. In this formalism, we try to estimate the elliptic flow in Pb+Pb collisions at $s_{NN}$ = 2.76 TeV at the LHC for different centralities. The elliptic flow ( $v_{2}$ ) of identified particles seems to be described quite well in the available $p_{T}$ range. An approach, which combines the non-extensive nature of particle production in $p + p$ collisions through an evolution in kinetic theory using BTE, with BGBW equilibrium distribution is successful in describing the spectra and elliptic flow in heavy-ion collisions.
Comments:
9 pages and 12 Figures, Published version in EPJA
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1709.06354 [pdf]
EPJA(2018)·21 citations
05
[Submitted on 19 Sept 2017] (cross-list from hep-ph)
Role of Multi-Parton Interactions on $J / ψ$ production in $p + p$ collisions at LHC Energies
Dhananjaya Thakur🇮🇳 · Sudipan De🇮🇳 · Raghunath Sahoo🇮🇳 · Soumya Dansana🇮🇳
The production mechanism of quarkonia states in hadronic collisions is still to be understood by the scientific community. In high-multiplicity $p + p$ collisions, Underlying Event (UE) observables are of major interest. The Multi-Parton Interactions (MPI) is a UE observable, where several interactions occur at the partonic level in a single $p + p$ event. This leads to dependence of particle production on event multiplicity. If the MPI occurs in a harder scale, there will be a correlation between the yield of quarkonia and total charged particle multiplicity. The ALICE experiment at the Large Hadron Collider (LHC) in $p + p$ collisions at $s$ = 7 and 13 TeV has observed an approximate linear increase of relative $J / ψ$ yield ( $\frac{d N _{J / ψ} / d y}{< d N _{J / ψ} / d y >}$ ) with relative charged particle multiplicity density ( $\frac{d N _{c h} / d y}{< d N _{c h} / d y >}$ ). In our present work we have performed a comprehensive study of the production of charmonia as a function of charged particle multiplicity in $p + p$ collisions at LHC energies using pQCD-inspired multiparton interaction model, PYTHIA8 tune 4C, with and without Color Reconnection (CR) scheme. A detail multiplicity and energy dependent study is performed to understand the effects of MPI on $J / ψ$ production. The ratio of $ψ (2 S)$ to $J / ψ$ is also studied as a function of charged particle multiplicity at LHC energies.
Comments:
Version accepted for publication in Physical Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1709.06358 [pdf]
PRD(2018)·44 citations
06
[Submitted on 19 Sept 2017] (cross-list from hep-ph)
Hyperfine splitting in ordinary and muonic hydrogen
Oleksandr Tomalak🇩🇪
We provide an accurate evaluation of the two-photon exchange correction to the hyperfine splitting of S energy levels in muonic hydrogen exploiting the corresponding measurements in electronic hydrogen. The proton structure uncertainty in the calculation of $α^{5}$ contribution is sizably reduced.
Comments:
5 pages, 4 figures, update in radiative corrections, the resulting HFS is provided, version published in Eur. Phys. J. A 54: 3 (2018)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
1709.06544 [pdf]
EPJA(2018)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE

Spectroscopy of Exotic Hadrons Formed from Dynamical Diquarks

Dissipative Properties and Isothermal Compressibility of Hot and Dense Hadron Gas using Non-extensive Statistics

Elliptic Flow in Pb+Pb Collisions at sNN​​ = 2.76 TeV at the LHC Using Boltzmann Transport Equation with Non-extensive Statistics

Role of Multi-Parton Interactions on J/ψ production in p+p collisions at LHC Energies

Hyperfine splitting in ordinary and muonic hydrogen

Affiliations

Elliptic Flow in Pb+Pb Collisions at $s_{NN}$ = 2.76 TeV at the LHC Using Boltzmann Transport Equation with Non-extensive Statistics

Role of Multi-Parton Interactions on $J / ψ$ production in $p + p$ collisions at LHC Energies