Thursday, June 21, 2018, 16:00
WHGA Auditorium
Greg Smith, Jefferson Lab
Abstract:
The ep elastic scattering experiment used to extract an asymmetry at
Q²=0.0248 (GeV/c)² will be described. The precision obtained
on the final result is ±9.3 ppb - the most precise ep asymmetry ever
measured. Some of the backgrounds and corrections applied in the
experiment will be explained and quantified, and some of the
experimental challenges will be described.
Several methods used to extract consistent values of the proton's weak
charge QW(p) from our asymmetry measurement will be outlined.
From the proton's weak charge, a result for the fundamental standard
model parameter sin²ϑW is obtained at the energy
scale of our experiment. We compare that to the few other determinations
of sin²ϑW available, as well as the
predicted behaviour based on SM input.
We also show the multi-TeV mass reach for beyond-the-Standard-Model
physics obtained from our determination of the proton's weak charge, and
discuss our sensitivity to specifc examples of new particles like
leptoquarks. We conclude by providing flavor-independent constraints on
all new semi-leptonic parity-violating physics obtained from our result.