Measurement of the $\frac{F_2^n}{F_2^p}$ ratio in the JLab MARATHON experiment

The $\frac{F_2^n}{F_2^p}$ structure function ratio has been measured previously from Deep Inelastic Scattering, using proton and deuterium targets to extract the $F_2^p$ $F_2^n$ structure functions respectively as well as the$\frac{d}{u}$ quark distribution function ratio. The lack of a free neutron target has made the extraction of $F_2^n$ challenging due to nuclear corrections, which result in large uncertainties in the $\frac{F_2^n}{F_2^p}$ and $\frac{d}{u}$ quark distribution function in the high x region. Likewise, various theory predictions based on SU(6) symmetry, pQCD, and the diquark model make different predictions for both ratios in the limit x $\rightarrow$ 1, all of which fit within the present uncertainty of $\frac{F_2^n}{F_2^p}$ at large x. To avoid the issues related with extracting $F_2^n$, MARATHON, a experiment currently running in Hall A at Jefferson Lab, used $^3He$ and $^3H$, to extract $\frac{F_2^n}{F_2^p}$ and thus $\frac{d}{u}$ by exploiting the isospin symmetry of the A=3 mirror nuclei. This will result in the determination of the $\frac{F_2^n}{F_2^p}$ and $\frac{d}{u}$ ratios with minimal theoretical uncertainties. This work is supported by NSF Grants PHY-1405814 and PHY-1714809 (Kent State University), and DOE Contract DE-AC05-06OR23177 (JLab)