arXiv subjects

S. J. Puglia

Publications and source records attributed to S. J. Puglia.

8 recordsLinked to original sources

arXiv2007

Effective Field Theory for Dilute Fermions with Pairing

Effective field theory (EFT) methods for a uniform system of fermions with short-range, natural interactions are extended to include pairing correlations, as part of a program to develop a systematic Kohn-Sham density functional theory (DFT) for medium and heavy nuclei. An effective action formalism for local composite operators leads to a free-energy functional that includes pairing by applying an inversion method order by order in the EFT expansion. A consistent renormalization scheme is demonstrated for the uniform system through next-to-leading order, which includes induced-interaction corrections to pairing.

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arXiv2002

Density Functional Theory for a Confined Fermi System with Short-Range Interaction

Effective field theory (EFT) methods are applied to density functional theory (DFT) as part of a program to systematically go beyond mean-field approaches to medium and heavy nuclei. A system of fermions with short-range, natural interactions and an external confining potential (e.g., fermionic atoms in an optical trap) serves as a laboratory for studying DFT/EFT. An effective action formalism leads to a Kohn-Sham DFT by applying an inversion method order-by-order in the EFT expansion parameter. Representative results showing the convergence of Kohn-Sham calculations at zero temperature in the local density approximation (LDA) are compared to Thomas-Fermi calculations and to power-counting estimates.

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arXiv2002

What Do We Know About the Strange Magnetic Radius?

We analyze the q^2-dependence of the strange magnetic form factor, \GMS(q^2), using heavy baryon chiral perturbation theory (HBChPT) and dispersion relations. We find that in HBChPT a significant cancellation occurs between the O(p^2) and O(p^3) loop contributions. Consequently, the slope of \GMS at the origin displays an enhanced sensitivity to an unknown O(p^3) low-energy constant. Using dispersion theory, we estimate the magnitude of this constant, show that it may have a natural size, and conclude that the low-q^2 behavior of \GMS could be dominated by nonperturbative physics. We also discuss the implications for the interpretation of parity-violating electron scattering measurements used to measure \GMS(q^2).

hep-ph↗

arXiv2000

Octet Baryon Charge Radii, Chiral Symmetry and Decuplet Intermediate States

We compute the octet baryon charge radii to O(1/Heavy^3) in heavy baryon chiral perturbation theory. We examine the effect of including the decuplet of spin-3/2 baryons explicitly. We find that it does no t improve the level of agreement between the HBchiPT and experimental values for the Sigma^- charge radius.

hep-ph↗

arXiv2000

Chiral Symmetry and the Parity-Violating $NNπ$ Yukawa Coupling

We construct the complete SU(2) parity-violating (PV) $π, N, Δ$ interaction Lagrangian with one derivative, and calculate the chiral corrections to the PV Yukawa $NNπ$ coupling constant $h_π$ through ${\cal O}(1/Λ_χ^3)$ in the leading order of heavy baryon expansion. We discuss the relationship between the renormalized $\hpi$, the measured value of $\hpi$, and the corresponding quantity calculated microscopically from the Standard Model four-quark PV interaction.

hep-ph↗

arXiv2000

The Nucleon Anapole Moment and Parity-Violating ep Scattering

Parity-violating (PV) interactions among quarks in the nucleon induce a PV $γNN$ coupling, or anapole moment (AM). We compute electroweak gauge-independent contributions to the AM through ${\cal O}(1/\lamchis)$ in chiral perturbation theory. We estimate short-distance PV effects using resonance saturation. The AM contributions to PV electron-proton scattering slightly enhance the axial vector radiative corrections, R_A^p, over the scale implied by the Standard Model when weak quark-quark interactions are neglected. We estimate the theoretical uncertainty associated with the AM contributions to R_A^p to be large, and discuss the implications for the interpretation PV of ep scattering.

hep-ph↗

arXiv1999

Baryon Octet magnetic moments in $χ$PT: More on the importance of the Decuplet

We address the impact of treating the decuplet of spin-3/2 baryons as an explicit degree of freedom in the chiral expansion of the magnetic moments of the octet of spin-1/2 baryons. We carry out a complete calculation of the octet moments to O(1/\lamchic), including decuplet contributions to the chiral loops. In contrast to results of previous analyses, we find that inclusion of the decuplet preserves the convergence behavior of the chiral expansion implied by power counting arguments.

hep-ph↗

arXiv1996

Anomalous Chiral Action from the Path-Integral

By generalizing the Fujikawa approach, we show in the path-integral formalism: (1) how the infinitesimal variation of the fermion measure can be integrated to obtain the full anomalous chiral action; (2) how the action derived in this way can be identified as the Chern-Simons term in five dimensions, if the anomaly is consistent; (3) how the regularization can be carried out, so as to lead to the consistent anomaly and not to the covariant anomaly. Our method uses Schwinger's ``proper-time'' representation of the Green's function and the gauge invariant point-splitting technique. We find that the consistency requirement and the point-splitting technique allow both an anomalous and a non-anomalous action. In the end, the nature of the vacuum determines whether we have an anomalous theory, or, a non-anomalous theory

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