William & Mary ScholarWorks

Welcome! William & Mary ScholarWorks preserves and provides access to the research and creative output of William & Mary's faculty, staff, and students.

UPDATE 18th JUNE 2025: Our repository has migrated from Digital Commons to Open Repository DSpace as of this summer. Additional updates and improvements will continue through the Fall semester. Thank you for your patience during this transition.

Recent Submissions

Open Access
Is there an A(y) problem in low-energy neutron–proton scattering?
(2008) Gross, Franz; Stadler, Alfred; Data science
We calculate Ay in neutron–proton scattering for the interactions models WJC-1 and WJC-2 in the Covariant Spectator Theory. We find that the recent 12 MeV measurements performed at TUNL are in better agreement with our results than with the Nijmegen Phase Shift Analysis of 1993, and after reviewing the low-energy data, conclude that there is no Ay problem in low-energy np scattering.
Open Access
Using baryon octet magnetic moments and masses to fix the pion cloud contribution
(2010) Gross, Franz; Ramalho, G.; Tsushima, K.; Data science
Using SU(3) symmetry to constrain the πBB′ couplings, assuming SU(3) breaking comes only from one- loop pion cloud contributions, and using the covariant spectator theory to describe the photon coupling to the quark core, we show how the experimental masses and magnetic moments of the baryon octet can be used to constrain the strength of the pion cloud contributions to the octet, and hence the nucleon, form factors at Q² = 0. Keywords: Baryon octet, Magnetic moments, Pion cloud
Open Access
Making the case for Jefferson Lab
(2011) Gross, Franz; Data science
This chapter is a personal account of the initial planning and competition for a new laboratory, which eventually became known as the Thomas Jefferson National Accelerator Facility, with the official nickname "Jefferson Lab." The period covered starts as far back as 1964, with the introduction of quarks, and extends up to the late 1980s after the initial team was assembled, the superconducting design was in place, and construction was well underway. I describe some of the major experiments that were proposed to justify the laboratory, reflect on the present status of those initially proposed experiments, and very briefly outline some of the new ideas that emerged after the laboratory was constructed. The science is presented in a simple manner intended for a lay audience, with some of the ideas illustrated by cartoons that were often used in popular lectures given during this period.
Open Access
Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory
(2016) Biernat, Elmar; Peña, M. T.; Ribeiro, J. E.; Stadler, A.; Gross, Franz; Data science
Weproposeamodelforthequark-antiquarkinteractioninMinkowskispace using the Covariant Spectator Theory. We show that with an equal-weighted scalar- pseudoscalar structure for the confining part of our interaction kernel the axial-vector Ward-Takahashi identity is preserved and our model complies with the Adler-zero con- straint for π-π-scattering imposed by chiral symmetry.
Open Access
Precise calculations of the deuteron quadrupole moment
(2015) Gross, Franz; Data science
Recently, two calculations of the deuteron quadrupole moment have have given predictions that agree with the measured value to within 1%, resolving a long-standing discrepancy. One of these uses the covariant spectator theory (CST) and the other chiral effective field theory (χEFT). In this talk I will first briefly review the foundations and history of the CST, and then compare these two calculations with emphasis on how the same physical processes are being described using very different language. The comparison of the two methods gives new insights into the dynamics of the low energy NN interaction.