Limitations of the heavy-baryon expansion as revealed by a pion-mass dispersion relation
Date
2012
Authors
Hall, J.
Pascalutsa, V.
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Journal article
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European Physical Journal C, 2012; 72(11):1-9
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Jonathan M.M. Hall, Vladimir Pascalutsa
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Abstract
The chiral expansion of nucleon properties such as mass, magnetic moment, and
magnetic polarizability are investigated in the framework of chiral
perturbation theory, with and without the heavy-baryon expansion. The analysis
makes use of a pion-mass dispersion relation, which is shown to hold in both
frameworks. The dispersion relation allows an ultraviolet cutoff to be
implemented without compromising the symmetries. After renormalization, the
leading-order heavy-baryon loops demonstrate a stronger dependence on the
cutoff scale, which results in weakened convergence of the expansion. This
conclusion is tested against the recent results of lattice quantum
chromodynamics simulations for nucleon mass and isovector magnetic moment. In
the case of the polarizability, the situation is even more dramatic as the
heavy-baryon expansion is unable to reproduce large soft contributions to this
quantity. Clearly, the heavy-baryon expansion is not suitable for every
quantity.
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Extent: 9p.
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© Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica 2012