Nuclear Theory·nucl-th

Tuesday·February 14, 2017

10 papers—6 primary·4 cross-listed

07
Feasibility Studies for Single Transverse-Spin Asymmetry Measurements at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC)
Daniel Kikoła🇵🇱 · Miguel García Echevarria🇪🇸 · Cynthia Hadjidakis🇫🇷 · Jean-Philippe Lansberg🇫🇷 · Cedric Lorcé🇫🇷 · Laure Massacrier🇫🇷 · Catarina Marques Quintans🇵🇹 · Andrea Signori🇺🇸 · Barbara Trzeciak🇳🇱
The measurement of Single Transverse-Spin Asymmetries, $A_{N}$ , for various quarkonium states and Drell-Yan lepton pairs can shed light on the orbital angular momentum of quarks and gluons, a fundamental ingredient of the proton-spin puzzle. The AFTER@LHC proposal combines a unique kinematic coverage and large luminosities thanks to the Large Hadron Collider beams to deliver precise measurements, complementary to the knowledge provided by collider experiments such as at RHIC. In this paper, we report on sensitivity studies for $J / ψ$ , $Υ$ and Drell-Yan $A_{N}$ done using the performance of LHCb-like or ALICE-like detectors, combined with polarised gaseous hydrogen and helium-3 targets. In particular, such analyses will provide us with new insights and knowledge about transverse-momentum-dependent parton distribution functions for quarks and gluons and on twist-3 collinear matrix elements in the proton and the neutron.
↳ hep-exhep-phnucl-exnucl-thFew Body Syst.(2017)·44 citations
08
Heavy Flavours in Quark-Gluon Plasma
Seyong Kim🇰🇷
Recent progresses in lattice studies of heavy quark and quarkonium at non-zero temperature are discussed. Formulating a tail of spectral functions as a transport coefficient allows lattice determination of momentum diffusion coefficient ( $κ$ ) for charm quark in the heavy quark mass limit and lattice determination of heavy quark/heavy anti-quark chemical equilibration rate in NRQCD. Quenched lattice study on a large volume gives $κ / T^{3} = 1.8 \dots 3.4$ in the continuum limit. A recent study with $N_{f} = 2 + 1$ configurations estimates the charmonium chemical equilibration rate $Γ_{chem}$ . At $T = 400$ MeV with $M \sim 1.5$ GeV, $Γ_{chem}^{- 1} \sim 150$ fm/c. Earlier results from the two studies (with different lattice setups and with different Bayesian priors) which calculate bottomonium correlators using NRQCD and employ Bayesian method to calculate spectral functions are summarized: $Υ (1 S)$ survives upto $T \sim 1.9 T_{c}$ and excited states of $Υ$ are sequentially suppressed. The spectral functions of $χ_{b 1}$ channel shows a Bayesian prior dependence of its thermal behavior: the $χ_{b 1}$ spectral function with MEM prior shows melting above $T_{c}$ but that with a new Bayesian prior hints survival of $χ_{b 1}$ upto $\sim 1.6 T_{c}$ . Preliminary results from the efforts to understand the difference in the behavior of $χ_{b 1}$ spectral function is given.
↳ hep-lathep-phnucl-thPoS(2017)·3 citations
09
The $1/ N_{c}$ expansion in hadron effective field theory
Guo-Ying Chen🇨🇳
We study the $N_{c}$ scalings of pion-nucleon and nucleon-nucleon scatterings and find that a consistent large $N_{c}$ counting can be established if we assume Witten's counting rules are applied to matrix elements or scattering amplitudes which use the relativistic normalization for the nucleons. With the pionless effective field theory, we also find that the $S$ -wave nucleon-nucleon interaction is so strong that it should be treated nonperturbatively at the leading order in the $1/ N_{c}$ expansion. By summing all the leading order diagrams, we find that the deuteron binding energy is of order $1/ N_{c}$ . In contrast, meson-meson interaction is so weak that loosely-bound meson-meson molecular states may not exist in the large $N_{c}$ limit.
↳ hep-phnucl-thCommun.Theor.Phys.(2018)·4 citations
10
On the solution of linearized (linear in S-matrix) Balitsky-Kovchegov equation
Raktim Abir🇮🇳 · Mariyah Siddiqah🇮🇳
We revisited solution of a linearized form of leading order Balitsky-Kovchegov equation (linear in S-matrix for dipole-nucleus scattering). Here we adopted dipole transverse width dependent cutoff in order to regulate the dipole integral. We also have taken care of all the higher order terms (higher order in the cutoff) that have been reasonably neglected before. The solution reproduces both McLerran-Venugopalan type initial condition (Gaussian in scaling variable) and Levin-Tuchin solution (Gaussian in logarithm of scaling variable) in the appropriate limits. It also connects this two opposite limits smoothly with better accuracy for sets of rescaled rapidity when compared to numerical solutions of full leading order Balitsky-Kovchegov equation.
↳ hep-phhep-thnucl-thPRD(2017)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Feasibility Studies for Single Transverse-Spin Asymmetry Measurements at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC)

Heavy Flavours in Quark-Gluon Plasma

The 1/Nc​ expansion in hadron effective field theory

On the solution of linearized (linear in S-matrix) Balitsky-Kovchegov equation

Affiliations

The $1/ N_{c}$ expansion in hadron effective field theory