Download or read book A Precision Measurement of Parity Violation in Moller Scattering written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports on E158, an experiment located in End Station A at the Stanford Linear Accelerator Center (SLAC). E158 has made the first observation of the parity violating right-left asymmetry (A[sub PV]) in fixed-target low-Q[sup 2] Moeller scattering. At tree level, A[sub PV] (expected to be around -150 ppb) is directly proportional to 1/4 - sin[sup 2] [theta][sub W]. A precision measurement of A[sub PV] at low Q[sup 2] allows the running of sin[sup 2] [theta][sub W] to be compared to the Standard Model prediction. Disagreements between the two might provide evidence for new physics at the TeV scale. This thesis presents the first physics data from E158, taken in the spring of 2002. The data were taken by scattering longitudinally polarized electrons at 45.0 and 48.3 GeV off a liquid hydrogen target at a Q[sup 2] of 0.027 GeV[sup 2]. A 60 meter long spectrometer/collimator system and a cooper-quartz calorimeter were used to detect the Moeller signal electrons. Both devices will be described in detail. The right-left parity violating asymmetry in Moeller scattering has been measured to be -152.3 [+-] 29.0(stat) [+-] 30.9(syst) ppb. The value of sin[sup 2] [theta][sub W] derived from this measurement is 0.2370 [+-] 0.0025(stat) [+-] 0.0026(syst), in comparison with the Standard Model prediction of 0.2387 [+-] 0.0007.
Download or read book A Precision Measurement of Parity Violation in M ller Scattering written by David R. Relyea and published by . This book was released on 2003 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Precision Measurement of the Weak Mixing Angle in Moller Scattering at Low Q 2 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The electroweak theory has been probed to a high level of precision at the mass scale of the Z° through the joint contributions of LEP at CERN and the SLC at SLAC. The E158 experiment at SLAC complements these results by measuring the weak mixing angle at a Q2 of 0.026 (GeV/c)2, far below the weak scale. The experiment utilizes a 48 GeV longitudinally polarized electron beam on unpolarized atomic electrons in a target of liquid hydrogen to measure the parity-violating asymmetry A{sup PV} in Moeller scattering. The tree-level prediction for A{sup PV} is proportional to 1-4 sin2 [theta]{sub W}. Since sin2 [theta]{sub W} ≈ 0.25, the effect of radiative corrections is enhanced, allowing the E158 experiment to probe for physics effects beyond the Standard Model at the TeV scale. This work presents the results from the first two physics runs of the experiment, covering data collected in the year 2002. The parity-violating asymmetry A{sup PV} was measured to be A{sup PV} = -158 ppb ± 21 ppb (stat) ± 17 ppb (sys). The result represents the first demonstration of parity violation in Moeller scattering. The observed value of A{sup PV} corresponds to a measurement of the weak mixing angle of sin2 [theta]{sub W}{sup eff} = 0.2380 ± 0.0016(stat) ± 0.0013(sys), which is in good agreement with the theoretical prediction of sin2 [theta]{sub W}{sup eff} = 0.2385 ± 0.0006 (theory).
Download or read book Precision Measurement of the Weak Mixing Angle in Moller Scattering written by and published by . This book was released on 2005 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Moeller) scattering: A{sub PV} = ( -131 ± 14 (stat.) ± 10 (syst.)) x 10−9, leading to the determination of the weak mixing angle sin2 [theta]{sub W}{sup eff} = 0.2397 ± 0.0010 (stat.) ± 0.0008 (syst.), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2 [theta]{sub W}{sup eff} at the Z° pole, the running of the weak mixing angle is observed with over 6[sigma] significance. The measurement sets constraints on new physics effects at the TeV scale.
Download or read book SLAC E158 written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The E158 experiment at SLAC will make the first measurement of parity violation in Moller scattering. The left-right cross-section asymmetry (ALR) in the elastic scattering of a 45-GeV polarized electron beam with unpolarized electrons in a liquid hydrogen target will be measured. This will give a precise measurement of the weak mixing angle, with delta(sin2 theta{sub W}{sup eff}) (approximately) 0.0008 (at Q2 = 0.03GeV2).
Download or read book Measurement of the Weak Mixing Angle in Moller Scattering written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The weak mixing parameter, sin2 [theta]{sub w}, is one of the fundamental parameters of the Standard Model. Its tree-level value has been measured with high precision at energies near the Z° pole; however, due to radiative corrections at the one-loop level, the value of sin2 [theta]{sub w} is expected to change with the interaction energy. As a result, a measurement of sin2 [theta]{sub w} at low energy (Q2 “m{sub Z}, where Q2 is the momentum transfer and m{sub Z} is the Z boson mass), provides a test of the Standard Model at the one-loop level, and a probe for new physics beyond the Standard Model. One way of obtaining sin2 [theta]{sub w} at low energy is from measuring the left-right, parity-violating asymmetry in electron-electron (Moeller) scattering: A{sub PV} = [sigma]{sub R}-[sigma]{sub L}/[sigma]{sub R}+[sigma]{sub L}, where [sigma]{sub R} and [sigma]{sub L} are the cross sections for right- and left-handed incident electrons, respectively. The parity violating asymmetry is proportional to the pseudo-scalar weak neutral current coupling in Moeller scattering, g{sub ee}. At tree level g{sub ee} = (1/4 -sin2 [theta]{sub w}). A precision measurement of the parity-violating asymmetry in Moeller scattering was performed by Experiment E158 at the Stanford Linear Accelerator Center (SLAC). During the experiment, H"0 GeV longitudinally polarized electrons scattered off unpolarized atomic electrons in a liquid hydrogen target, corresponding to an average momentum transfer Q2 H"0.03 (GeV/c)2. The tree-level prediction for A{sub PV} at such energy is H"00 ppb. However one-loop radiative corrections reduce its value by H"0%. This document reports the E158 results from the 2002 data collection period. The parity-violating asymmetry was found to be A{sub PV} = -160 ± 21 (stat.) ± 17 (syst.) ppb, which represents the first observation of a parity-violating asymmetry in Moeller scattering. This value corresponds to a weak mixing angle at Q2 = 0.026 (GeV/c)2 of sin2 [theta]{sub w{ovr MS}} = 0.2379 ± 0.0016 (stat.) ± 0.0013 (syst.), which is -0.3 standard deviations away from the Standard Model prediction: sin2 [theta]{sub w{ovr MS}}{sup predicted} = 0.2385 ± 0.0006 (theory). The E158 measurement of sin2 [theta]{sub w} at a precision of [delta](sin2 [theta]{sub w}) = 0.0020 provides new physics sensitivity at the TeV scale.
Download or read book Observation of Parity Nonconservation in Moller Scattering written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors report a measurement of the parity-violating asymmetry in fixed target electron-electron (Moeller) scattering: A{sub PV} = ( -175 ± 30 (stat.) ± 20 (syst.)) x 10−9. This first direct observation of parity nonconservation in Moeller scattering leads to a measurement of the electron's weak charge at low energy Q{sub W}{sup e} = -0.053 ± 0.011. This is consistent with the Standard Model expectation at the current level of precision: sin2 [theta]{sub W} (M{sub Z}){sub {ovr MS}} = 0.0024 (stat.) ± 0.0016 (syst.) ± 0.0006 (theory).
Download or read book From Parity Violation to Hadronic Structure and more written by Serge Kox and published by Springer Science & Business Media. This book was released on 2007-06-07 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Almost 50 years after the proposal of Lee and Young in 1956 to test the hypothesis of parity violation in weak interactions and the subsequent experimental verification of parity violation by C. S. Wu, parity violation has today become a useful property of weak interactions. This is due to the fact that the focus nowadays has changed: parity violation in weak interactions is no more a topic of investigation but is used as a tool in many different fields ranging from nuclear physics to the search for the hidden extra dimensions requested by string theory. For our first workshop which took place June 5-8, 2002, at the Institut fiir Ke- physik of the Johannes Gutenberg-Universitat Mainz, we concentrated on the in vestigation of the strangeness contribution in the nucleon. This book contains the refereed and selected papers of the second workshop "From Parity Violation to Hadron Structure and more (Part II)", which took place June 8-11, in the Labo- toire de Physique Subatomique et de Cosmologie, in Grenoble. These papers appear in EPJAdirect, the electronic-only part of EPJA, and they are accessible without restrictions. They will also appear in printed form and can be ordered through Springer. The excellent presentations show the dramatic and steady progress in the accuracy of measured parity violating asymmetries over the last few years.
Download or read book Parity Violation In Electron Scattering Proceedings Of The Workshop written by E J Beise and published by World Scientific. This book was released on 1990-08-23 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings cover the recent progress and future directions of parity violation in electron scattering. Both experimental and theoretical issues are discussed, such as those of hadronic structure, radiative corrections, and tests of the standard model. There are three sessions, the first of which serves as a general overview of theory and experiment. The second session deals with the technical aspects of making a measurement of the parity violating asymmetry in electron scattering, including not only detector design but polarized electron beams and beam polarimeters.. The remaining session covers the corrections to lowest order parity violating cross sections.
Download or read book From Parity Violation to Hadronic Structure and more written by K. de Jager and published by Springer Science & Business Media. This book was released on 2008-06-21 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Parity Violation In Atoms And In Polarized Electron Scattering written by Marie-anne Bouchiat and published by World Scientific. This book was released on 1999-07-13 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last few years there has been considerable progress in improving the accuracy of parity violation experiments in electron scattering at high energy and in atomic physics. Recent results are a challenge to the standard electroweak theory and our understanding of hadron structure. This book is an extensive review of the advances in this field. The theoretical framework is presented at a pedagogical level, experiments and future projects are reviewed, and the results and their interpretation are discussed in depth.
Download or read book A Search for New Physics at the TeV Scale Via a Precise Measurement of the Weak Mixing Angle in Moller Scattering written by Waled S. Emam and published by . This book was released on 2004 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Discrete Symmetries and CP Violation written by Marco Sozzi and published by Oxford University Press. This book was released on 2008-01-24 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book takes a fresh approach to the teaching of discrete symmetries which are central to fundamental physics: mirror symmetry, matter/anti-matter symmetry, and time reversal. It is self-contained and includes detailed discussions of relevant experiments - conveying some of the fascination and intellectual challenges of experimental physics.
Download or read book Parity Violation in Electron Scattering written by E. J. Beise and published by World Scientific Publishing Company. This book was released on 1990 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings cover the recent progress and future directions of parity violation in electron scattering. Both experimental and theoretical issues are discussed, such as those of hadronic structure, radiative corrections, and tests of the standard model. There are three sessions, the first of which serves as a general overview of theory and experiment. The second session deals with the technical aspects of making a measurement of the parity violating asymmetry in electron scattering, including not only detector design but polarized electron beams and beam polarimeters.. The remaining session covers the corrections to lowest order parity violating cross sections.
Download or read book Hadron Structure in Electroweak Precision Measurements written by Nathan L. Hall and published by Springer. This book was released on 2015-07-24 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis examines the γZ box contribution to the weak charge of the proton. Here, by combining recent parity-violating electron-deuteron scattering data with our current understanding of parton distribution functions, the author shows that one can limit this model dependence. The resulting construction is a robust model of the γγ and γZ structure functions that can also be used to study a variety of low-energy phenomena. Two such cases are discussed in this work, namely, the nucleon’s electromagnetic polarizabilities and quark-hadron duality. By using phenomenological information to constrain the input structure functions, this important but previously poorly understood radiative correction is determined at the kinematics of the parity-violating experiment, QWEAK, to a degree of precision more than twice that of the previous best estimate. A detailed investigation into available parametrizations of the electromagnetic and interference cross-sections indicates that earlier analyses suffered from the inability to correctly quantify their model dependence.
Download or read book GEANT4 Simulation of Detector Properties in the MOLLER Experiment written by Christopher R. Haufe and published by . This book was released on 2015 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: To explore the existence of new physics beyond the scope of the electroweak theory, international collaborations of nuclear physicists have constructed several precision-measurement experiments. One of these is the MOLLER experiment---a low-energy parity violation experiment that will utilize the 12 GeV upgrade of Jefferson Lab's CEBAF accelerator. The motivation of this experiment is to measure the parity violating asymmetry of Møller scattering in a liquid hydrogen target. This measurement would allow for a more precise determination of the electron's weak charge and the weak mixing angle. While still in its planning stages, the MOLLER experiment requires a detailed simulation framework in order to determine how the project should be run in the future. The simulation framework for MOLLER, called "remoll", is written in C++ and uses the GEANT4 framework and libraries. It has recently been updated to include the full detector geometry of the experiment. The viability of the detector geometry in the real experiment will rely on a detailed analysis of the detector's properties through simulation. The first part of this analysis assesses the impact of particle crosstalk in the design.
Download or read book A Measurement of the Parity Violating Asymmetry in Aluminum and Its Contribution to a Measurement of the Proton s Weak Charge written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Q_weak experiment, which ran at the Thomas Jefferson National Accelerator Facility, made a precision measurement of the proton's weak charge, Q^p_W. The weak charge is extracted via a measurement of the parity-violating asymmetry in elastic electron-proton scattering from hydrogen at low momentum transfer (Q^2=0.025 GeV^2). This result is directly related to the electroweak mixing angle, sin^2(Theta_W), a fundamental parameter in the Standard Model of particle physics. This provides a precision test sensitive to new, as yet unknown, fundamental physics. This dissertation focuses on two central corrections to the Q_weak measurement: the target window contribution and sub-percent determination of the electron beam polarization. The aluminum target windows contribute approximately 30% of the measured asymmetry. Removal of this background requires precise measurements of both the elastic electron-aluminum scattering rate and its parity-violating asymmetry. The results reported here are the most precise measurement of the Q_weak target dilution and asymmetry to date. The parity-violating asymmetry for the aluminum alloy was found to be 1.6174 +/- 0.0704 (stat.) +/- 0.0113 (sys.) parts-per-million. The first sub-percent precision polarization measurements made from the Hall C Moller polarimeter are also reported, with systematic uncertainties of 0.84%.
