[PDF] Parity Violation Inelastic Scattering Experiments At 6 Gev And 12 Gev Jefferson Lab eBook

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Release : 2015
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We report on the measurement of parity-violating asymmetries in the deep inelastic scattering and nucleon resonance regions using inclusive scattering of longitudinally polarized electrons from an unpolarized deuterium target. The effective weak couplings C$_{2q}$ are accessible through the deep-inelastic scattering measurements. Here we report a measurement of the parity-violating asymmetry, which yields a determination of 2C$_{2u}$ - C$_{2d}$ with an improved precision of a factor of five relative to the previous result. This result indicates evidence with 95% confidence that the 2C$_{2u}$ - C$_{2d}$ is non-zero. This experiment also provides the first parity-violation data covering the whole resonance region, which provide constraints on nucleon resonance models. Finally, the program to extend these measurements at Jefferson Lab in the 12 GeV era using the Solenoidal Large Intensity Device was also discussed.

Author : Xiaochao Zheng
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Page : pages
File Size : 43,69 MB
Release : 2006
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The parity-violating asymmetry in e-$^2$H deep inelastic scattering (DIS) can be used to extract the weak neutral-current coupling constants $C_{2q}$. A measurement of this asymmetry at two $Q^2$ values is planned at Jefferson Lab. Results from this experiment will provide a value of $2C_{2u}-C_{2d}$ to a precision of $\pm 0.03$, a factor of eight improvement over our current knowledge. If all hadronic effects can be understood, this results will provide information on possible extensions of the Standard Model, complementary to other experiments dedicated to new physics searches. Presented here are the physics motivation, experimental setup, potential hadronic effects and their implications, and the future of PV DIS at Jefferson Lab.

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File Size : 10,8 MB
Release : 1998
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Experiments on parity violation in electron scattering measure the asymmetry A =?{sub R} -?{sub L}/?{sub R} +?{sub L} where?{sub R(L)} is the cross section for Right(Left) handed longitudinally polarized electrons. This asymmetry arises, in first order, from the interference between photon and Z-boson exchange amplitudes. Experiments make two basic uses of the Z-boson as a probe in electron-quark or electron-nucleon scattering. Historically the first usage was to test the electroweak theory in regions of kinematics where the hadronic structure is sufficiently understood. They discuss the application of higher energies at Jefferson Lab to repeat the SLAC e-D deep inelastic parity violation experiment [1] at a level of precision ≈ 0.5% in sin2?{sub W} which would be a useful constrain on extensions of the Standard Model [2]. The second, more recent usage of the Z-boson probe is to assume the Standard Model is correct at about the 1% level and use this as a unique method to address fundamental issues of nucleon structure, such as: (1) are the strange quarks an important component of the nucleon [3]; (2) In deep inelastic scattering, are the high momentum quarks u or d quarks? To address the first question, they discuss the feasibility of extending the HAPPEX experiment to higher Q2. For the second question, they discuss a possible measurement of the ratio of valence quarks d/u in the proton using deep inelastic parity violation.

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Page : 180 pages
File Size : 47,78 MB
Release : 2013
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The parity-violating asymmetry in deep inelastic scattering (PVDIS) offers us a useful tool to study the weak neutral couplings and the hadronic structure of the nucleon, and provides high precision tests on the Standard Model. During the 6 GeV PVDIS experiment at the Thomas Jefferson National Accelerator Facility, the parity-violating asymmetries A{sub PV} of a polarized electron beam scattering off an unpolarized deuteron target in the deep inelastic scattering region were precisely measured at two Q2 values of 1.1 and 1.9 (GeV/c)2. The asymmetry at Q2=1.9 (GeV/c)2 can be used to extract the weak coupling combination 2C2u - C2d, assuming the higher twist effect is small. The extracted result from this measurement is in good agreement with the Standard Model prediction, and improves the precision by a factor of five over previous data. In addition, combining the asymmetries at both Q2 values provides us extra knowledge on the higher twist effects. The parity violation asymmetries in the resonance region were also measured during this experiment. These results are the first APV data in the resonance region beyond the [Delta] (1232). They provide evidence that the quark hadron duality works for APV at the (10-15)% level, and set constraints on nucleon resonance models that are commonly used for background calculations to other parity-violating electron scattering measurements.

Author : Paul Souder
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Page : pages
File Size : 28,89 MB
Release : 2005
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We review the program of parity violation in the scattering of polarized electrons at JLab. Results are presented from recent experiments measuring the weak form factors, which in turn measure the contribution of strange quarks to the elastic form factors. In addition, we discuss the physics of parity violation in deep inelastic scattering, which will become possible with the upgrade of the JLab energy to 12 GeV.

Author : K. de Jager
Publisher : Springer Science & Business Media
Page : 256 pages
File Size : 24,97 MB
Release : 2008-06-21
Category : Science
ISBN : 3540744134

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This book contains the proceedings of the third international workshop on From Parity Violation to Hadronic Structure and More. The many applications of parity violation are way beyond the scope of what Lee and Yang could have imagined fifty years after their proposal. For the physics topics discussed during this workshop, the application of parity violation has become a standard work horse allowing for the extraction of many physics topics in different experiments.

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File Size : 46,62 MB
Release : 2007
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The advent of the 12-GeV upgrade at JLab will present an excellent opportunity to study parity violation in deep inelastic scattering at high values of x. The physics issues in this domain include charge symmetry violation, quark-quark correlations in the nucleon, and tests of the Standard Model. This program will require a high-luminosity detector with high acceptance for scattering angles up to about 35°. A possible design for a solenoidal spectrometer that meets this requirement is suggested.

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Page : 79 pages
File Size : 23,48 MB
Release : 2013
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An experiment that measured the parity violating (PV) asymmetry Ad in e-2H deep inelastic scattering (DIS) at Q2 ~ 1.10 and 1.90 (GeV/c)2 and xB ~ 0.3 was completed in experimental Hall A at the Thomas Jefferson National Accelerator Facility. The asymmetry can be used to extract the neutral weak coupling combination (2C2u-C2d), providing a factor of five to six improvement over the current world data. To achieve this precision, asymmetries of the 10-4 level needed to be measured at event rates up to 500 kHz with high electron detection efficiency and high pion background rejection capability. A specialized scaler-based counting data acquisition system (DAQ) with hardware-based particle identification was successfully implemented. The statistical quality of the asymmetry measurement agreed with the Gaussian distribution to over five orders of magnitudes and the experimental goal of 3-4% statistical uncertainty was achieved. The design and performance of the new DAQ system is presented with the preliminary asymmetry results given in the end.

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Page : pages
File Size : 31,61 MB
Release : 2006
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Parity violating electron scattering has become a well established tool which has been used, for example, to probe the Standard Model and the strange-quark contribution to the nucleon. While much of this work has focused on elastic scattering, the RES-Parity experiment, which has been proposed to take place at Jefferson Laboratory, would focus on inelastic scattering in the low-Q2, low-W domain. RES-Parity would search for evidence of quark-hadron duality and resonance structure with parity violation in the resonance region. In terms of parity violation, this region is essentially unexplored, but the interpretation of other high-precision electron scattering experiments will rely on a reasonable understanding of scattering at lower energy and low-W through the effects of radiative corrections. RES-Parity would also study nuclear effects with the weak current. Because of the intrinsic broad band energy spectrum of neutrino beams, neutrino experiments are necessarily dependent on an untested, implicit assumption that these effects are identical to electromagnetic nuclear effects. RES-Parity is a relatively straight forward experiment. With a large expected asymmetry (~ 0.5 x 10-4) these studies may be completed with in a relatively brief period.

Author : Jacques Arvieux
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Page : 11 pages
File Size : 19,32 MB
Release : 2005
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A short history of parity violation is given, leading to the present use of parity violating electron scattering for studying the nucleon internal structure. The status of the G0 and HAPPEX experiments presently running at Jefferson Lab is discussed. Some preliminary results are shown.