[en] We are planning an experiment at JLab to measure parity-violation in deep inelastic scattering to high precision over a broad kinematic range. The goal of the experiment is to test the Standard Model, search for charge symmetry violation at the quark level, and to search for higher twist effects due to quark-quark interactions. We will also be able to measure the d/u ratio for the nucleon and search for nuclear effects in deep inelastic scattering.

[en] 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 35degree. A possible design for a solenoidal spectrometer that meets this requirement is suggested.

[en] An experiment designed to measure parity violation in the deep inelastic scattering of electrons from deuterium by using a novel solenoidal spectrometer (SoLID) has recently been approved at JLab. The main goal of the experiment is to make a precise measurement of the parity-violating coupling of the electron to the axial current of the quark. By covering a broad range of kinematics, the experiment will also search for charge symmetry violation in the structure functions. In addition the experiment is sensitive to di-quarks.

[en] Experiments at JLab, Mainz, and MIT-Bates are probing weak nucleon form factors by measuring the parity-violating asymmetry in the scattering of polarized electrons from nucleons. The goal of this work is the extraction of the contribution of strange quarks to nucleon form factors. (author)

[en] Parity violation in the scattering of polarized electrons is a unique tool for nuclear and particle physics that is presently being exploited at JLab, Mainz, MIT-Bates, and SLAC. One focus of these experiments is the measurement of the contribution of strange quarks to the elastic form factors of the nucleon. Recently, results on this topic from MIT-Bates and JLab have been reported. Future experiments, motivated by the search for strange form factors as well as testing the Standard Model and measuring the radius of the neutron distribution, are described

[en] Recent experiments at JLab and MIT-Bates measuring the parity-violating asymmetry in the scattering of polarized electrons from nucleons have provided new, precise measurements of weak nucleon form factors. The focus of these experiments is the extraction of the contribution of strange quarks to nucleon form factors

[en] This contribution, together with the following one by E. J. Beise, will cover the topic of experiments using polarized electrons to study the parity-violating electroweak interference effects. The role of Bates in the evolution of the field is emphasized. The initial motivation of these experimental efforts was tests of the Standard Model. Examples that I will describe include deep inelastic scattering from deuterium at SLAC and elastic scattering from ¹²C at Bates. Recently, the focus has shifted to the search for strange form factors in the elastic scattering from hydrogen. I will present recent results on the subject from the HAPPEX collaboration at JLab. Finally, future experiments that will measure very small asymmetries at SLAC and JLab are described

[en] A green laser (CW, 532 nm) based Fabry-Perot cavity for high precision Compton Polarimetry is under development in Hall A of the Jefferson Laboratory. In this paper, we present the principle and the preliminary studies for our test cavity.

[en] This Conceptual Design Report (CDR) presents the compelling scientific case for upgrading the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab to 12 GeV. Such a facility will make profound contributions to the study of hadronic matter. In particular, it will allow breakthrough programs to be launched in four main areas: (1) The experimental study of gluonic excitations in order to understand the funda- mentally new dynamics that underpins all of nuclear physics: the confinement of quarks. Theoretical conjectures, now strengthened by lattice QCD simulations, indicate that the most spectacular new prediction of QCD - quark confinement - occurs through the formation of a string-like 'flux tube' between quarks. This conclusion (and proposed mechanisms of flux tube formation) can be tested by determining the spectrum of the gluonic excitations of mesons. (2) The Fundamental Structure of the Nuclear Building Blocks. A vast improvement in our knowledge of the fundamental structure of the proton and neutron can be achieved. Not only can existing 'deep inelastic scattering' cross sections be extended for the first time to cover the critical region where their basic three-quark structure dominates, but also measure- ments of new 'deep exclusive scattering' cross sections will open the door to a comprehensive characterization of these wavefunctions using the framework of the Generalized Parton Distributions; these data will provide access to information on the correlations among the quarks. These studies will be complemented by detailed measurements of elastic and transition form factors, determining the dynamics underlying the quark-gluon structure through measurements of their high-momentum-transfer behavior and providing essential constraints on their description. (3) The Physics of Nuclei. A broad and diversified program of measurements that (taken together with the hadron studies outlined above) aims to provide a firm intellectual under-pinning for all of nuclear physics by answering the question 'How does the phenomenological description of nuclei as nucleons interacting via an effective interaction parameterized using meson exchange arise from the underlying dynamics of quarks and gluons?' It has two main components: The emergence of nuclei from QCD. Experiments aimed at understanding how the description of nuclei in terms of nucleons interacting via the N - N force arises from the more fundamental QCD description. It includes the investigation of the partonic structure of nuclei, of short range structures in nuclei, and of the modification of the quark-gluon structure of the nucleons and mesons by the nuclear environment. Fundamental QCD processes in the nuclear arena. Experiments aimed at understanding how hadron-hadron interactions arise from the underlying quark-gluon structure of QCD. (4) Tests of the Standard Model of electro-weak interactions and the determination of fundamental parameters of this model. Precision, parity-violating electron scattering experiments made feasible by the 12 GeV Upgrade have the sensitivity to search for deviations from the Standard Model that could signal the presence of new physics. Precision measurements of the two-photon decay widths and transition form factors of the three neutral pseudoscalar mesons π⁰, η, and η' via the Primakoff effect will lead to a significant improvement on our knowledge of chiral symmetry in QCD, in particular on the ratios of quark masses and on chiral anomalies. This science program has expanded significantly since the project was first presented to the Nuclear Sciences Advisory Committee (NSAC) in the form of a White Paper [WP01] produced as part of the 2001-2002 NSAC Long Range Planning Process and since the pre-Conceptual Design Report (pCDR) produced in June 2004 to document the Upgrade science and experimental equipment plans [pCDR]. While focusing on science, this document also provides a brief description of the required detector and accelerator upgrades so that it can serve as an overview of the entire plan for the 12 GeV project. This CDR was developed from the documentation presented in the pCDR [pCDR] and further discussions within the community since that document was released. We acknowledge here the many contributions of the entire JLab community, and note that the author list at the end of the pCDR includes the names of all contributors to the effort known to us. Many of them commented extensively on the earlier drafts, resulting in a much-improved document. This document would have been impossible without their intelligence, enthusiasm, time, and just plain hard work.

[en] We describe the research and development work for the P2 experiment which aims for a high precision determination of the weak mixing angle sin² θ_W to a precision of 0.15% at a four-momentum transfer of 4.5 x 10^-3 GeV². This accuracy, comparable to existing measurements at the Z pole, allows for a sensitive test of the Standard Model up to a mass scale of 50 TeV, extendable to 60 TeV. The weak mixing angle is connected to the weak charge of the proton which will be extracted from a measurement of the parity violating cross section asymmetry -39.94 x 10^-9 in elastic electron-proton scattering. A total accuracy of 0.57 x 10^-9 is achievable in a measurement time of 11000 h using a 150 μA polarized electron beam impinging on a 60 cm liquid hydrogen target. The P2 asymmetry is smaller than any asymmetry measured so far in electron scattering with an unprecedented goal for the accuracy. The use of a solenoid spectrometer with 100% φ-acceptance as well as an atomic hydrogen trap polarimeter are new features, which have never before been used in parity-violation experiments. In order to collect the enormous statistics required for this measurement, the new Mainz Energy-Recovering Superconducting Accelerator (MESA) is under construction. Plans for the associated beam control system and the polarimetry are described in this article as well. A liquid hydrogen high-power target with an extremely low noise level of 10 ppm needs to be designed and constructed. We report in addition on the conceptual design of the P2 spectrometer, its Cherenkov detectors, the integrating read-out electronics as well as the ultra-thin, fast tracking detectors. The physics program of the MESA facility comprises indirect, high precision search for physics beyond the Standard Model, measurement of the neutron distribution in nuclear physics, single-spin asymmetries, and a possible future extension to the measurement of hadronic parity violation. (orig.)