Nuclear Theory·nucl-th

Wednesday·May 15, 2019

8 papers—3 primary·5 cross-listed

04
The Photon and Light $1^{--}$ Mesons
R.S. Longacre🇺🇸
In this paper we look into the world data related to the photon and the connection to light mesons with the same spin parity quantum number as the photon $J^{p} = 1^{-}$ .
↳ hep-phnucl-th0 citations
05
Hyperon I: Study of the $Λ (1405)$
A.V. Anisovich🇩🇪 · A.V. Sarantsev🇩🇪 · V.A. Nikonov🇩🇪 · V. Burkert🇺🇸 · R.A. Schumacher🇺🇸 · U. Thoma🇩🇪 · E. Klempt🇩🇪
Low-energy data on the three charge states in $γ p \to K^{+} (Σ π)$ from CLAS at JLab, on $K^{-} p \to π^{0} π^{0} Λ$ and $π^{0} π^{0} Σ$ from the Crystal Ball at BNL, bubble chamber data on $K^{-} p \to π^{-} π^{+} π^{\pm} Σ^{\mp}$ , low-energy total cross sections on $K^{-}$ induced reactions, and data on the $K^{-} p$ atom are fitted with the BnGa partial-wave-analysis program. We find that the data can be fitted well with just one isoscalar spin-1/2 negative-parity pole, the $Λ (1405)$ , and background contributions.
↳ nucl-exnucl-th8 citations
06
Compton Scattering off Pions and Electromagnetic Polarizabilities
Murray Moinester🇮🇱 · Stefan Scherer🇩🇪
The electric ( $α_{π}$ ) and magnetic ( $β_{π}$ ) Compton polarizabilities of both the charged and the neutral pion are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD). Pion polarizabilities affect the shape of the $γ π \to γ π$ Compton scattering angular distribution at back scattering angles and $γ γ \to π π$ absolute cross sections. Theory derivations are given of the $γ π \to γ π$ Compton scattering differential cross section, dispersion relations, and sum rules in terms of the polarizabilities. We review experimental charged and neutral polarizability studies and theoretical predictions. The $π^{0}$ polarizabilities were deduced from DESY Crystal Ball $γ γ \to π^{0} π^{0}$ data, but with large uncertainties. The charged pion polarizabilities were deduced most recently from (1) radiative pion Primakoff scattering $π^{-} Z \to π^{-} Z γ$ at CERN COMPASS, (2) two-photon pion pair production $γ γ \to π^{+} π^{-}$ at SLAC Mark II, and (3) radiative pion photoproduction $γ p \to γ π^{+} n$ from the proton at MAMI in Mainz. A stringent test of chiral perturbation theory (ChPT) is possible based on comparisons of precision experimental charged pion polarizabilities with ChPT predictions. Only the CERN COMPASS charged pion polarizability measurement has acceptably small uncertainties. Its value $α_{π^{\pm}} - β_{π^{\pm}} = (4.0 \pm 1.8) \times 1 0^{- 4} fm^{3}$ agrees well with the two-loop ChPT prediction $α_{π^{\pm}} - β_{π^{\pm}} = (5.7 \pm 1.0) \times 1 0^{- 4} fm^{3}$ , strengthening the identification of the pion with the Goldstone boson of chiral symmetry breaking in QCD.
↳ hep-phhep-exnucl-exnucl-thInt.J.Mod.Phys.A(2019)·24 citations
07
Heavy quarkonium suppression beyond the adiabatic limit
Jacob Boyd🇺🇸 · Thomas Cook🇺🇸 · Ajaharul Islam🇺🇸 · Michael Strickland🇺🇸
Many prior studies of in-medium quarkonium suppression have implicitly made use of an adiabatic approximation in which it was assumed that the heavy quark potential is a slowly varying function of time. In the adiabatic limit, one can separately determine the in-medium breakup rate and the medium time evolution, folding these together only at the end of the calculation. In this paper, we relax this assumption by solving the 3d Schrodinger equation in real-time in order to compute quarkonium suppression dynamically. We compare results obtained using the adiabatic approximation with real-time calculations for both harmonic oscillator and realistic complex heavy quark potentials. Using the latter, we find that, for the Upsilon(1s), the difference between the adiabatic approximation and full real-time evolution is at the few percent level, however, for the Upsilon(2s), we find that the correction can be as large as 18% in low temperature regions. For the J/Psi, we find a larger difference between the dynamical evolution and the adiabatic approximation, with the error reaching approximately 36%.
↳ hep-phnucl-thPRD(2019)·24 citations
08
Hadronization within the Non-Extensive Approach and the Evolution of the Parameters
Keming Shen🇭🇺 · Gergely Gábor Barnaföldi🇭🇺 · Tamás Sándor Biró🇭🇺
We review transverse momentum distributions of various identified charged particles stemming from high energy collisions fitted by various non-extensive distributions as well as by the usual Boltzmann-Gibbs statistics. We investigate the best-fit formula with the obtained $χ^{2} / n df$ values. We find that the physical mass and $s$ scaling become more explicit with heavier produced hadrons in both proton-proton and heavy-ion collisions. The spectral shape parameters, in particular the temperature $T$ and the non-extensive Tsallis parameter $q$ , do exhibit an almost linear dependence with the centrality-dependence in heavy-ion collisions.
↳ hep-phnucl-thEPJA(2019)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE

The Photon and Light 1−− Mesons

Hyperon I: Study of the Λ(1405)

Compton Scattering off Pions and Electromagnetic Polarizabilities

Heavy quarkonium suppression beyond the adiabatic limit

Hadronization within the Non-Extensive Approach and the Evolution of the Parameters

Affiliations

The Photon and Light $1^{--}$ Mesons

Hyperon I: Study of the $Λ (1405)$