scholarly journals Subleading contributions to the nuclear scalar isoscalar current

2020 ◽  
Vol 56 (9) ◽  
Author(s):  
H. Krebs ◽  
E. Epelbaum ◽  
U.-G. Meißner
Keyword(s):  
Effective Field Theory ◽  
Quark Mass ◽  
Axial Vector ◽  
Effective Field ◽  
Current Operator ◽  
Nuclear Forces ◽  
Chiral Effective Field Theory ◽  
Zero Momentum ◽  
Quark Mass Dependence ◽  
Scalar Current

Abstract We extend our recent analyses of the nuclear vector, axial-vector and pseudoscalar currents and derive the leading one-loop corrections to the two-nucleon scalar current operator in the framework of chiral effective field theory using the method of unitary transformation. We also show that the scalar current operators at zero momentum transfer are directly related to the quark mass dependence of the nuclear forces.

scholarly journals Nuclear currents in chiral effective field theory

2020 ◽  
Vol 56 (9) ◽  
Author(s):  
Hermann Krebs
Keyword(s):  
Field Theory ◽  
Chiral Symmetry ◽  
Effective Field Theory ◽  
Unitary Transformation ◽  
Axial Vector ◽  
Vector Current ◽  
Effective Field ◽  
Axial Vector Current ◽  
Leading Order ◽  
Chiral Effective Field Theory

Abstract In this article, we review the status of the calculation of nuclear currents within chiral effective field theory. After formal discussion of the unitary transformation technique and its application to nuclear currents we give all available expressions for vector, axial-vector currents. Vector and axial-vector currents are discussed up to order Q with leading-order contribution starting at order $$Q^{-3}$$ Q - 3 . Pseudoscalar and scalar currents will be discussed up to order $$Q^0$$ Q 0 with leading-order contribution starting at order $$Q^{-4}$$ Q - 4 . This is a complete set of expressions in next-to-next-to-next-to-leading-order (N$$^3$$ 3 LO) analysis for nuclear scalar, pseudoscalar, vector and axial-vector current operators. Differences between vector and axial-vector currents calculated via transfer-matrix inversion and unitary transformation techniques are discussed. The importance of a consistent regularization is an additional point which is emphasized: lack of a consistent regularization of axial-vector current operators is shown to lead to a violation of the chiral symmetry in the chiral limit at order Q. For this reason a hybrid approach at order Q, discussed in various publications, is non-applicable. To respect the chiral symmetry the same regularization procedure needs to be used in the construction of nuclear forces and current operators. Although full expressions of consistently regularized current operators are not yet available, the isoscalar part of the electromagnetic charge operator up to order Q has a very simple form and can be easily regularized in a consistent way. As an application, we review our recent high accuracy calculation of the deuteron charge form factor with a quantified error estimate.

NUCLEAR FORCES AND FEW NUCLEON SYSTEMS IN CHIRAL EFFECTIVE FIELD THEORY

2009 ◽  
Vol 24 (11n13) ◽  
pp. 921-930
Author(s):  
HERMANN KREBS
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Degrees Of Freedom ◽  
Effective Field ◽  
Chiral Expansion ◽  
Light Nuclei ◽  
Nuclear Forces ◽  
Chiral Effective Field Theory ◽  
Promising Tool ◽  
Many Body Systems

Using chiral effective field theory (EFT) with explicit Δ degrees of freedom we calculated nuclear forces up to next-to-next-to-leading order (N2LO). We find a much improved convergence of the chiral expansion in all peripheral partial waves. We also present a novel lattice EFT method developed for systems with larger number of nucleons. Combining Monte Carlo lattice simulations with EFT allows one to calculate the properties of light nuclei, neutron and nuclear matter. Accurate description of two-nucleon phase-shifts and ground state energy ratio of dilute neutron matter up to corrections of higher orders show that lattice EFT is a promising tool for quantitative studies of low-energy few- and many-body systems.

CHIRAL EFFECTIVE POTENTIAL WITH DELTA DEGREES OF FREEDOM

2009 ◽  
Vol 24 (02n03) ◽  
pp. 511-514
Author(s):  
H. KREBS ◽  
E. EPELBAUM ◽  
ULF-G. MEIßNER
Keyword(s):  
Effective Field Theory ◽  
Degrees Of Freedom ◽  
Effective Field ◽  
Chiral Expansion ◽  
Leading Order ◽  
Nuclear Forces ◽  
Charge Symmetry Breaking ◽  
Chiral Effective Field Theory ◽  
Charge Symmetry ◽  
Full Theory

Using chiral effective field theory (EFT) with explicit Δ degrees of freedom we calculated nuclear forces up to next-to-next-to-leading order (NNLO). We found much better convergence of the chiral expansion in all peripheral partial waves. We also observe strong cancellations between charge-symmetry-breaking (CSB) contributions due to nucleon- and Δ-mass splittings in the two-pion-exchange potentials. The CSB potentials appear to be weaker in the Δ-full theory.

scholarly journals Power counting for nuclear forces in chiral effective field theory

2016 ◽  
Vol 25 (05) ◽  
pp. 1641006 ◽  
Author(s):  
Bingwei Long
Keyword(s):  
Field Theory ◽  
Renormalization Group ◽  
Effective Field Theory ◽  
Present Note ◽  
Effective Field ◽  
Power Counting ◽  
Point Of View ◽  
Nuclear Forces ◽  
Chiral Effective Field Theory ◽  
Group Invariance

The present note summarizes the discourse on power counting issues of chiral nuclear forces, with an emphasis on renormalization-group invariance. Given its introductory nature, I will lean toward narrating a coherent point of view on the concepts, rather than covering comprehensively the development of chiral nuclear forces in different approaches.

scholarly journals Chiral effective field theory and nuclear forces

2011 ◽  
Vol 503 (1) ◽  
pp. 1-75 ◽  
Author(s):  
R. Machleidt ◽  
D.R. Entem
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Effective Field ◽  
Nuclear Forces ◽  
Chiral Effective Field Theory
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