2,593 research outputs found
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
Four-nucleon force in chiral effective field theory
We derive the leading contribution to the four-nucleon force within the
framework of chiral effective field theory. It is governed by the exchange of
pions and the lowest-order nucleon-nucleon contact interaction and includes
effects due to the nonlinear pion-nucleon couplings and the pion self
interactions constrained by the chiral symmetry of QCD. The resulting
four-nucleon force does not contain any unknown parameters and can be tested in
few- and many-nucleon studies.Comment: 4 pages, 4 figure
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
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
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
Regularization, renormalization and "peratization" in effective field theory for two nucleons
We discuss conceptual aspects of renormalization in the context of effective
field theories for the two-nucleon system. It is shown that, contrary to
widespread belief, renormalization scheme dependence of the scattering
amplitude can only be eliminated up to the order the calculations are
performed. We further consider an effective theory for an exactly solvable
quantum mechanical model which possesses a long- and short-range interaction to
simulate pionful effective field theory. We discuss the meaning of low-energy
theorems in this model and demonstrate their validity in calculations with a
finite cutoff as long as it is chosen of the order of the hard scale
in the problem. Removing the cutoff by taking the limit
yields a finite result for the scattering amplitude but violates the low-energy
theorems and is, therefore, not compatible with the effective field theory
framework.Comment: 22 pages, 2 figures, to appear in Eur. Phys. J.
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