2025/03/17 by Miesch, Nicholas, Shuryak, Edward, Zahed, Ismail
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2503.13273
The standard description of the nucleon in the non-relativistic quark model is an 1S,L=0 state without orbital motion. Yet, there are several indications from phenomenology that an admixture of states with nonzero orbital motion maybe substantial. In this paper we focus on the ``second shell" of the nucleon excitations (D-shell), for which we give a modern description of the wave functions. We follow it by investigating what we call a ``maximal mixing" scenario, assuming a hypothetical long-range tensor force. We give the explicit wave functions for all states, before and after mixing, and re-assess many predictions such as the magnetic moments, the standard and transitional form-factors from the nucleon to N^*. Unexpectedly, in this scenario we can reproduce the long-puzzling features of the Roper resonance N^*( 1440). But even in this extreme case, the admixture of the 1D,L=2 state to a nucleon remains significantly smaller than expected from phenomenology.