We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at backward angles at Q2=0.038 (GeV/c)2. This quantity provides a determination ...of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A=-3.51+/-0.57 (stat)+/-0.58 (syst) ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also consistent with theoretical predictions.
The strangeness magnetic moment of the proton is shown to be small in the chiral quark model. The dominant loop contribution is due to kaons. The
K
∗
loop contributions are proportional to the ...difference between the strange and light constituent quark masses or
m
K
∗
−2
and therefore small. The loop fluctuations that involve radiative transitions between
K
∗
mesons and kaons are small, when the cutoff scale in the loops is taken to be close to the chiral symmetry restoration scale. The net loop amplitude contribution to the strangeness magnetic moment of the proton is about −0.05, which falls within the uncertainty range of the experimental value.
We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q2=0.15, 0.25 (GeV/c)2. The results are inconsistent ...with calculations solely using the elastic nucleon intermediate state and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A(n) provides a direct probe of the imaginary component of the 2gamma exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.
The cryogenic target for the experiment at Jefferson lab Covrig, S.D.; Beise, E.J.; Carr, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2005, Letnik:
551, Številka:
2-3
Journal Article
The cryogenic target for the G 0 experiment at Jefferson lab Covrig, S.D.; Beise, E.J.; Carr, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2005, Letnik:
551, Številka:
2
Journal Article
Recenzirano
A cryogenic horizontal single loop target has been designed, built, tested and operated for the
G
0
experiment in Hall C at Jefferson Lab. The target cell is 20
cm long, the loop volume is 6.5
l and ...the target operates with the cryogenic pump fully immersed in the fluid. The target has been designed to operate at 30
Hz rotational pump speed with either liquid hydrogen or liquid deuterium. The high-power heat exchanger is able to remove 1000
W of heat from the liquid hydrogen, while the nominal electron beam with current of
40
μ
A
and energy of 3
GeV deposits about 320
W of heat into the liquid. The increase in the systematic uncertainty due to the liquid hydrogen target is negligible on the scale of a parity violation experiment. The global normalized yield reduction for
40
μ
A
beam is about 1.5% and the target density fluctuations contribute less than 238
ppm (parts per million) to the total asymmetry width, typically about 1200
ppm, in a
Q
2
bin.
Phys.Rev. C62 (2000) 045204 The chiral quark model describes the strangeness components of the light
quarks as fluctuations into strange mesons and quarks. The single strange
pseudoscalar and vector ...meson loop fluctuations of the constituent $u$- and
$d$-quarks give rise to only very small strangeness form factors for the
proton. This result is in line with recent experimental results, given their
wide uncertainty range.
The chiral quark model describes the strangeness components of the light quarks as fluctuations into strange mesons and quarks. The single strange pseudoscalar and vector meson loop fluctuations of ...the constituent \(u\)- and \(d\)-quarks give rise to only very small strangeness form factors for the proton. This result is in line with recent experimental results, given their wide uncertainty range.
Nucl.Phys.A665:353-364,2000 The strangeness magnetic moment of the proton is shown to be small in the
chiral quark model. The dominant loop contribution is due to kaons. The K^*
loop contributions ...are proportional to the difference between the strange and
light constituent quark masses or $m_{K^*}^{-2}$ and therefore small. The loop
fluctuations that involve radiative transitions between K^* mesons and kaons
are small, when the cut-off scale in the loops is taken to be close to the
chiral symmetry restoration scale. The net loop amplitude contribution to the
strangeness magnetic moment of the proton is about -0.05, which falls within
the uncertainty range of the experimental value.
PDF
