7 research outputs found
Recent results from the G(0) experiment
We have measured parity violating asymmetries in elastic electron-proton and quasi-elastic electrondeuteron scattering at backward electron angle. These measurements have been done at two momentum transfers : Q2 = 0.22 and 0.63 (GeV/c)2 . Together with our previous forward angle measurement [1], we can extract strange quark contributions to the electromagnetic form factors of the nucleon, as well as nucleon axial form factor coming from the neutral weak interaction. The results indicate a strange quark magnetic contribution close to zero at these Q2 , and a possible non zero strange quark electric contribution for the high Q2 . The ïŹrst Q2 behavior measurement of the nucleon axial form factor in elastic electron scattering shows a good agreement with radiative corrections calculated at Q2 = 0 and with a dipole form using the axial mass determined in neutrino scattering
Recommended from our members
Measurement of the beam-normal single-spin asymmetry for elastic electron scattering from C12 and Al27
We report measurements of the parity-conserving beam-normal single-spin
elastic scattering asymmetries on C and Al, obtained with
an electron beam polarized transverse to its momentum direction. These
measurements add an additional kinematic point to a series of previous
measurements of on C and provide a first measurement on Al.
The experiment utilized the Qweak apparatus at Jefferson Lab with a beam energy
of 1.158 GeV. The average lab scattering angle for both targets was 7.7
degrees, and the average for both targets was 0.02437 GeV (Q=0.1561
GeV). The asymmetries are = -10.68 0.90 stat) 0.57 (syst) ppm
for C and = -12.16 0.58 (stat) 0.62 (syst) ppm for
Al. The results are consistent with theoretical predictions, and are
compared to existing data. When scaled by Z/A, the Q-dependence of all the
far-forward angle (theta < 10 degrees) data from H to Al can be
described by the same slope out to GeV. Larger-angle data from
other experiments in the same Q range are consistent with a slope about twice
as steep
Recommended from our members
The MOLLER Experiment: An Ultra-Precise Measurement of the Weak Mixing Angle Using MĂžller Scattering
The physics case and an experimental overview of the MOLLER (Measurement Of a
Lepton Lepton Electroweak Reaction) experiment at the 12 GeV upgraded Jefferson
Lab are presented. A highlight of the Fundamental Symmetries subfield of the
2007 NSAC Long Range Plan was the SLAC E158 measurement of the parity-violating
asymmetry in polarized electron-electron (M{\o}ller) scattering. The
proposed MOLLER experiment will improve on this result by a factor of five,
yielding the most precise measurement of the weak mixing angle at low or high
energy anticipated over the next decade. This new result would be sensitive to
the interference of the electromagnetic amplitude with new neutral current
amplitudes as weak as from as yet undiscovered dynamics
beyond the Standard Model. The resulting discovery reach is unmatched by any
proposed experiment measuring a flavor- and CP-conserving process over the next
decade, and yields a unique window to new physics at MeV and multi-TeV scales,
complementary to direct searches at high energy colliders such as the Large
Hadron Collider (LHC). The experiment takes advantage of the unique opportunity
provided by the upgraded electron beam energy, luminosity, and stability at
Jefferson Laboratory and the extensive experience accumulated in the community
after a round of recent successfully completed parity-violating electron
scattering experiment