Nuclear Theory·nucl-th

Wednesday·September 25, 2019

5 papers—1 primary·4 cross-listed

02
Pion and kaon condensation at zero temperature in three-flavor $χ$ PT at nonzero isospin and strange chemical potentials at next-to-leading order
Prabal Adhikari🇺🇸 · Jens O. Andersen🇳🇴
We consider three-flavor chiral perturbation theory ( $χ$ PT) at zero temperature and nonzero isospin ( $μ_{I}$ ) and strange ( $μ_{S}$ ) chemical potentials. The effective potential is calculated to next-to-leading order (NLO) in the $π^{\pm}$ -condensed phase, the $K^{\pm}$ -condensed phase, and the $K^{0} / K ˉ^{0}$ -condensed phase. It is shown that the transitions from the vacuum phase to these phases are second order and take place when, $∣ μ_{I} ∣ = m_{π}$ , $∣ \frac{1}{2} μ_{I} + μ_{S} ∣ = m_{K}$ , and $∣ - \frac{1}{2} μ_{I} + μ_{S} ∣ = m_{K}$ , respectively at tree level and remains unchanged at NLO. The transition between the two condensed phases is first order. The effective potential in the pion-condensed phase is independent of $μ_{S}$ and in the kaon-condensed phases, it only depends on the combinations $\pm \frac{1}{2} μ_{I} + μ_{S}$ and not separately on $μ_{I}$ and $μ_{S}$ . We calculate the pressure, isospin density and the equation of state in the pion-condensed phase and compare our results with recent $(2 + 1)$ -flavor lattice QCD data. We find that the three-flavor $χ$ PT results are in good agreement with lattice QCD for $μ_{I} < 200$ MeV, however for larger values $χ$ PT produces values for observables that are consistently above lattice results. For $μ_{I} > 200$ MeV, the two-flavor results are in better agreement with lattice data. Finally, we consider the observables in the limit of very heavy $s$ -quarks, where they reduce to their two-flavor counterparts with renormalized couplings. The disagreement between the predictions of two and three flavor $χ$ PT can largely be explained by the differences in the experimental values of the low-energy constants.
↳ hep-phnucl-thJHEP(2020)·25 citations
03
Precision Model-Independent Bounds from Global Analysis of $b \to c ℓ ν$ Form Factors
Thomas D. Cohen🇺🇸 · Henry Lamm🇺🇸 · Richard F. Lebed🇺🇸
We present a model-independent global analysis of hadronic form factors for the semileptonic decays $b \to c ℓ ν$ that exploits lattice-QCD data, dispersion relations, and heavy-quark symmetries. The analysis yields predictions for the relevant form factors, within quantifiable bounds. These form factors are used to compute the semileptonic ratios $R (H_{c})$ and various decay-product polarizations. In particular, we find $R (D_{s}^{*}) = 0.20 (3)$ and $R (J / ψ) = 0.25 (3)$ , predictions that can be compared to results of upcoming LHCb measurements. In developing this treatment, we obtain leading-order NRQCD results for the nonzero-recoil relations between the $B_{c}^{+} \to {J / ψ, η_{c}}$ form factors.
↳ hep-phhep-exhep-latnucl-thPRD(2019)·30 citations
04
Nucleon strange electromagnetic form factors
C. Alexandrou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · S. Bacchio (The Cyprus Inst.)🇨🇾 · M. Constantinou (Temple Univ.)🇺🇸 · J. Finkenrath (The Cyprus Inst.)🇨🇾 · K. Hadjiyiannakou (The Cyprus Inst.)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · G. Koutsou (The Cyprus Inst.)🇨🇾
The role of the strange quarks on the low-energy interactions of the proton can be probed through the strange electromagnetic form factors. Knowledge of these form factors provides essential input for parity-violating processes and contributes to the understanding of the sea quark dynamics. We determine the strange electromagnetic form factors of the nucleon within the lattice formulation of Quantum Chromodynamics using simulations that include light, strange and charm quarks in the sea all tuned to their physical mass values. We employ state-of-the-art techniques to accurately extract the form factors for values of the momentum transfer square up to 0.8~GeV $^{2}$ . We find that both the electric and magnetic form factors are statistically non-zero. We obtain for the strange magnetic moment $μ^{s} = - 0.017 (4)$ , the strange magnetic radius $⟨ r_{M}^{2} ⟩^{s} = - 0.015 (9)$ ~fm $^{2}$ , and the strange charge radius $⟨ r_{E}^{2} ⟩^{s} = - 0.0048 (6)$ ~fm $^{2}$ .
↳ hep-lathep-phnucl-exnucl-thPRD(2020)·40 citations
05
Suppression of quarkonia in PbPb collisions at $s_{N N}$ = 5.02 TeV
Vineet Kumar🇮🇳 · Prashant Shukla🇮🇳 · Abhijit Bhattacharyya🇮🇳
We study different processes responsible for the modification of quarkonia yields in the medium produced in PbPb collisions at $s_{N N}$ = 5.02 TeV. The quarkonia and heavy flavour cross sections are estimated using the measurements in pp collisions at LHC energies and shadowing corrections are obtained using the EPS09 parametrizations. A kinetic model is used which incorporates quarkonia suppression inside the Quark Gluon Plasma (QGP), suppression due to hadronic comovers, and regeneration from recombination of heavy quark pairs. The quarkonia dissociation cross section due to gluon collisions, including both color-electric dipole and color-magnetic dipole transitions, has been employed. The regeneration rate is obtained using the principle of detailed balance. The effect of these processes on the nuclear modification factors for both $\Jpsi$ and $Υ$ in different ranges of transverse momentum $\pT$ and rapidity has been studied for PbPb collisions at $\sNN =$ 5.02 TeV. The calculations are compared with the available results from LHC experiments. Both the suppression and regeneration due to a QGP are effective in the low and intermediate $\pT$ range. The large observed suppression of $\Jpsi$ at $\pT >$ 10 GeV/ $c$ is larger than the suppression expected due to gluon dissociation.
↳ hep-phnucl-exnucl-thJ.Phys.G(2020)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Pion and kaon condensation at zero temperature in three-flavor χPT at nonzero isospin and strange chemical potentials at next-to-leading order

Precision Model-Independent Bounds from Global Analysis of b→cℓν Form Factors

Nucleon strange electromagnetic form factors

Suppression of quarkonia in PbPb collisions at sNN​​ = 5.02 TeV

Affiliations

Pion and kaon condensation at zero temperature in three-flavor $χ$ PT at nonzero isospin and strange chemical potentials at next-to-leading order

Precision Model-Independent Bounds from Global Analysis of $b \to c ℓ ν$ Form Factors

Suppression of quarkonia in PbPb collisions at $s_{N N}$ = 5.02 TeV