119418730
Large-Nc quark distributions in the delta and chiral logarithms in quark distributions of the nucleon
Abstract In a world with two quark flavors and a large number of colors ( N c ), the polarized and unpolarized quark distributions in the delta are completely determined by those in the nucleon up to relative O (1/N c 2 ) . In particular, we find q Δ (x)=[(1±2T z )u N (x)+(1∓2T z )d N (x)]/2(1+ O (1/N c 2 )) and Δq Δ (x)=[(5±2T z )Δu N (x)+(5∓2T z )Δd N (x)]/10(1+ O (1/N c 2 )) , where q = u , d and T z the charge state of a delta. The result can be used to estimate the leading chiral-logarithmic corrections to the quark distributions in the nucleon.
118576689
{pi}{pi} scattering in twisted mass chiral perturbation theory
In this report we describe both I=2 and I=0 {pi}{pi} scattering for twisted mass lattice QCD utilizing twisted mass chiral perturbation theory at next-to-leading order. Focusing on the lattice spacing (b) corrections, we demonstrate that in the exotic I=2, I{sub 3}={+-}2 channels ({pi}{sup {+-}}{pi}{sup {+-}}), the leading scaling violations of {pi}{pi} scattering at maximal twist begin at O(m{sub {pi}}{sup 2}b{sup 2}). This is not the case in any other isospin channel, for which the scaling violations at maximal twist begin at O(b{sup 2}). Furthermore, we demonstrate the existence of a mixing between the I=2, I{sub 3}=0 and I=0 scattering channels due to the breaking of isospin symmetry by the twisted mass term. The mixing term, although formally next-to-leading order, is relatively large, thus necessitating the use of a coupled channel analysis. We argue that this mixing likely renders the computation of the I=0 channel impractical with twisted mass lattice QCD.
123742236
Effective Field Theory in Nuclear Astrophysics
118840350
Universality of the EMC effect
Using effective field theory, we investigate nuclear modification of nucleon parton distributions (for example, the EMC effect). We show that the universality of the shape distortion in nuclear parton distributions (the factorisation of the Bjorken x and atomic number (A) dependence) is model independent and emerges naturally in effective field theory. We then extend our analysis to study the analogous nuclear modifications in isospin and spin-dependent parton distributions and generalised parton distributions.
119342728
Deuteron Compton scattering in effective field theory : Spin-dependent cross sections and asymmetries
Polarized Compton scattering on the deuteron is studied in nuclear effective field theory. A set of tensor structures is introduced to define 12 independent Compton amplitudes. The scalar and vector amplitudes are calculated up to next-to-next-to-leading order in low-energy power counting. Significant contribution to the vector amplitudes is found to come from the spin-orbit type of relativistic corrections. A double-helicity-dependent cross section {delta}{sub 1}d{sigma}/d{omega}=(d{sigma}{sub +1-1}-d{sigma}{sub +1+1})/2d{omega} is calculated to the same order, and the effect of the nucleon isoscalar spin-dependent polarizabilities is found to be smaller than the effect of isoscalar spin-independent ones. Contributions of spin-independent polarizabilities are investigated in various asymmetries, one of which has an effect as large as 12% (26%) at the center-of-mass photon energy 30 (50) MeV.
115761963
Comment on "Subleading Corrections to Parity Violating Pion Photoproduction"
In a recent preprint, hep-ph/0012253, Zhu et al. calculated a part of the next-to-leading order corrections to parity-violating pion photoproduction (pol)gamma p-> pi^+ n in heavy-baryon chiral perturbation theory. They claim they have found the contribution as large as the leading-order. If correct, the process will not be a clean way to extract the longest range PV pion-nucleon coupling constant h_{\pi NN}^(1), as was asserted in our previous publications (hep-ph/0011230, nucl-th/0011100). In this comment we show that there is no solid evidence to support Zhu et al.'s claim. Moreover, we show that the subleading parity-violating coupling h_V cannot be extracted from observables at the order of interest based on the formalism of effective field theory.
121652117
The L-G Phase Transition and the Nucleon–Nucleon Interaction Potential within QHD-I Model
The nucleon–nucleon interaction potential in hot/dense nuclear matter is studied within the QHD-I model. We find that a Yukawa potential, which contains attractive and repulsive terms, acting between nucleons is modified by the variation of the Debye mass. In particular, a nucleon system described by this Yukawa potential will be unbound at some critical T and μ. The critical point is very close to that of the L-G phase transition given in the literatures.
118394652
Dust, Ice, and Gas In Time (DIGIT) Herschel program first results A full PACS-SED scan of the gas line emission in protostar DK Chamaeleontis
Aims. We aim to study the composition and energetics of the circumstellar material of DK Cha, an intermediate-mass star in transition from an 
embedded configuration to a star plus disk stage, during this pivotal stage of its evolution. 
Methods. Using the range scan mode of PACS on the Herschel Space Observatory, we obtained a spectrum of DK Cha from 55 to 210 μm as part 
of the DIGIT key program. 
Results. Almost 50 molecular and atomic lines were detected, many more than the 7 lines detected in ISO-LWS. Nearly the entire ladder of CO 
from J = 14–13 to 38–37 (E_u/k = 4080 K), water from levels as excited as J_(K−1 K+1) = 7_(07) (E_u/k = 843 K), and OH lines up to E_u/k = 290 K were 
detected. 
Conclusions. The continuum emission in our PACS SED scan matches the flux expected by a model consisting of a star, a surrounding disk of 
0.03 M_⊙, and an envelope of a similar mass, supporting the suggestion that the object is emerging from its main accretion stage. Molecular, atomic, 
and ionic emission lines in the far-infrared reveal the outflow’s influence on the envelope. The inferred hot gas may be photon-heated, but some 
emission may be caused by C-shocks in the walls of the outflow cavity.
119453402
1S0 pairing correlation in symmetric nuclear matter with Debye screening effects
Abstract The 1 S 0 pairing of symmetric nuclear matter is discussed in the framework of relativistic nuclear theory with Dyson–Schwinger equations (DSEs). The in-medium nucleon and meson propagators are treated in a more self-consistent way through meson polarizations. The screening effects on mesons due to in-medium nucleon excitation are found to reduce the 1 S 0 pairing gap and shift remarkably the gap peak to low density region.
15079524
NON-ABELIAN MEDIUM EFFECTS IN QUARK–GLUON PLASMA
Based on the kinetic theory, the non-Abelian medium property of hot Quark–Gluon Plasma is investigated. The nonlinearity of the plasma comes from two aspects: The nonlinear wave–wave interaction and self-interaction of color field. The non-Abelian color permittivity is obtained by expanding the kinetic equations to third order. As an application, the nonlinear Landau damping rate and the nonlinear eigen frequency shift are calculated in the longwave length limit.
125746382
Heuristic approach to Unusual photon isospin mixing effects on the thermodynamics of compact nuclear matter