Bayesian analysis of light-front models and the nucleon's charmed sigma term

We present the results of a recent analysis to study the nucleon's charm sigma term, σ_{c c ¯}. We construct a minimal model in terms of light-front variables and constrain the range of possibilities using extant knowledge from deeply inelastic scattering (DIS) and Bayesian parameter estimation, ultimately computing σ_{c c ¯} in an explicitly covariant manner. We find a close correlation between a possible nonperturbative component of the charm structure function, F₂^{,IC c c ¯} , and σ_{c c ¯}. Independent of the prescription for the covariant relativistic quark-nucleon vertex, we determine σ_{c c ¯} under several different scenarios for the magnitude of intrinsic charm in DIS, namely ⟨x ⟩c_{+c ¯}=0.1 %, 0.35%, and 1%, obtaining for these σ_{c c ¯}=4 ±4 , 12 ±13 , and 32 ±34 MeV , respectively. These results imply the existence of a reciprocity between the intrinsic charm parton distribution function and σ_{c c ¯} such that new information from either DIS or improved determinations of σ_{c c ¯} could significantly impact constraints to the charm sector of the proton wave function.