Effective Field Theory and Isospin Violation in Few-Nucleon Systems

I discuss the leading and subleading isospin--breaking three--nucleon forces in the chiral effective field theory framework.Comment: 5 pages, 2 figures. Invited lead talk at the 19th European Conference on Few-Body Problems in Physics, Groningen, The Netherlands, August 23-27, 200

Chiral dynamics of few-nucleon systems

I discuss some recent developments in chiral effective field theory for few-nucleon systems.Comment: 8 pages, 6 figures, invited talk, International Nuclear Physics Conference (INPC 2007), Tokyo, Japan, June 3-8, 200

Chiral effective field theory for few-nucleon systems

Some recent developments in the description of nuclear forces and few--nucleon systems within the effective field theory approach are reviewed.Comment: 9 pages, 6 figures, plenary talk at 17th International IUPAP Conference on Few-body Problems in Physics, June 5-10, 2003, Durham, North Carolina, US

Nuclear forces with Delta-excitations up to next-to-next-to-leading order I: peripheral nucleon-nucleon waves

We study the two-nucleon force at next-to-next-to-leading order in a chiral effective field theory with explicit Delta degrees of freedom. Fixing the appearing low-energy constants from a next-to-leading order calculation of pion-nucleon threshold parameters, we find an improved convergence of most peripheral nucleon-nucleon phases compared to the theory with pions and nucleons only. In the delta-full theory, the next-to-leading order corrections are dominant in most partial waves considered.Comment: 16 pages, 10 figure

Neutral pion photoproduction off 3H and 3He in chiral perturbation theory

We calculate electromagnetic neutral pion production off three-nucleon bound states (3H, 3He) at threshold to leading one-loop order in the framework of chiral nuclear effective field theory. In addition, we analyze the dependence of the nuclear S-wave amplitude E_{0+} on the elementary neutron amplitude E_{0+}^{pi0 n} which in the case of 3He provides a stringent test of the prediction based on chiral perturbation theory. Uncertainties from higher order corrections are estimated.Comment: 6 pages, 3 figures, version accepted for publication in Phys. Lett. B, improved discussion of higher-order corrections, results unchange

Fluctuations of the initial color fields in high energy heavy ion collisions

In the Color Glass Condensate approach to the description of high energy heavy ion collisions, one needs to superimpose small random Gaussian distributed fluctuations to the classical background field, in order to resum the leading secular terms that result from the Weibel instability, that would otherwise lead to pathological results beyond leading order. In practical numerical simulations, one needs to know this spectrum of fluctuations at a proper time $\tau \ll Q_s^{-1}$ shortly after the collision, in the Fock-Schwinger gauge $A^\tau=0$. In this paper, we derive these fluctuations from first principles, by solving the Yang-Mills equations linearized around the classical background, with plane wave initial conditions in the remote past. We perform the intermediate steps in light-cone gauge, and we convert the results to the Fock-Schwinger gauge at the end. We obtain simple and explicit formulas for the fluctuation modes.Comment: 36 pages, 5 figures (final version, includes a brief discussion of the numerical implementation