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Book A Precision Measurement of the Weak Mixing Angle in Moller Scattering at Low Q 2

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).

Book Measurement of the Weak Mixing Angle in Moller Scattering

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.

Book Precision Measurement of the Weak Mixing Angle in Moller Scattering

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.

Book Antiquit s pr cieuses

Download or read book Antiquit s pr cieuses written by and published by . This book was released on 1922 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book A Search for New Physics at the TeV Scale Via a Precise Measurement of the Weak Mixing Angle in Moller Scattering

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:

Book Die r misch katholische Kirche

Download or read book Die r misch katholische Kirche written by and published by . This book was released on 1941 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book From Parity Violation to Hadronic Structure and more

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.

Book The Qweak Experiment A Search for New Physics at the TeV Scale

Download or read book The Qweak Experiment A Search for New Physics at the TeV Scale written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A new precision measurement of the parity violating analyzing power in longitudinally polarized electron scattering from the proton at very low Q^2 at an incident energy of 1.16 GeV is in the final stages of preparation for execution at Jefferson Laboratory (JLab). A 2200 hour measurement of the parity violating asymmetry in elastic electron-proton scattering at Q^2 = 0.03 (GeV/c)^2 employing 180 microamp of 85% polarized beam on a 0.35 m long liquid hydrogen target will determine the weak charge of the proton, Q_w = 1 - 4sin^2(theta_W), with 4% combined statistical and systematic errors. The Standard Model makes a firm prediction of Q_w, based on the 'running' of the weak mixing angle sin^2(theta_W) from the Z-pole down to lower energies. Any significant deviation of sin^2(theta_W) from its Standard Model prediction at low Q^2 would constitute a signal of new physics. In the absence of new physics, the envisaged experiment will provide a 0.3% determination of sin^2(theta_W), making this a very competitive measurement of the weak mixing angle. Complementary to the present experiment is a measurement of the weak charge of the electron in parity violating Moller scattering at 11 GeV, currently under consideration, with the upgraded CEBAF at JLab. The objective of that experiment would be a measurement of sin2(theta_W) with a precision comparable to or better than any individual measurement at the Z-pole.

Book Hadron Structure in Electroweak Precision Measurements

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.

Book Calorimetry In Particle Physics Proceedings Of The Tenth International Conference Calor02

Download or read book Calorimetry In Particle Physics Proceedings Of The Tenth International Conference Calor02 written by Ren-yuan Zhu and published by World Scientific. This book was released on 2003-01-16 with total page 921 pages. Available in PDF, EPUB and Kindle. Book excerpt: The International Conference on Calorimetry in Particle Physics is the major forum for the state-of-the-art developments of calorimetry technologies. The Tenth Conference was attended by more than 150 physicists from 16 countries and covered all aspects of calorimetric particle detection and measurements, with emphasis on high energy physics and astrophysics experiments.The proceedings contain three parts: introductory papers, contributed papers and perspective papers. The introduction starts with a historical review of calorimetry developments, and continues with overviews of the current status of calorimetry in high energy physics and astrophysics, which are followed by discussions on calorimetry in future accelerator facilities, such as linear colliders and the Super B factories. A “hot” technology regarding the “energy flow concept” is also discussed. The contributed papers are organized in 11 sessions. The perspective papers summarize the physics and limitation of calorimeter applications in high energy physics, astrophysics and medical industries.

Book From Parity Violation to Hadronic Structure and more

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.

Book Intersections of Particle and Nuclear Physics

Download or read book Intersections of Particle and Nuclear Physics written by Tony M. Liss and published by American Institute of Physics. This book was released on 2006-12-13 with total page 790 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a conference that explores areas of common interest between nuclear physicists, high energy (particle) physicists, and astrophysicists. These areas range from studies of the strong interactions that bind the nuclei together, to physics of the very early Universe. They include such topics as the detailed behavior of neutrinos and searches for "new physics", that is phenomena that cannot be accounted for by our current theories.