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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 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 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 A NEW MEASUREMENT OF THE WEAK MIXING ANGLE

Download or read book A NEW MEASUREMENT OF THE WEAK MIXING ANGLE written by and published by . This book was released on 2004 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The E158 experiment at SLAC has made the first measurement of parity violation in electron-electron (Moeller) scattering. The authors report a preliminary result using 50% of the accumulated data sample for the right-left parity-violating cross-section asymmetry (A{sub PV}) in the elastic scattering of 45 and 48 GeV polarized electron beams with unpolarized electrons in a liquid hydrogen target. They find A{sub PV} = ( -160 ± 21(stat.) ± 17(syst.)) · 10−9, with a significance of 6.3[sigma] for observing parity violation. In the context of the Standard Model, this yields a measurement of the weak mixing angle, sin2 [theta]{sub W}{sup {ovr MS}} (Q2 = 0.026GeV2) = 0.2379 ± 0.0016(stat.) ± 0.0013(syst.). They also present preliminary results for the first observation of a single-spin transverse asymmetry in Moeller scattering.

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 Lepton Photon Interactions At High Energies Lepton Photon 2017 Proceedings Of The 28th International Symposium

Download or read book Lepton Photon Interactions At High Energies Lepton Photon 2017 Proceedings Of The 28th International Symposium written by Wang Wei and published by World Scientific. This book was released on 2020-02-27 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: The latest of the 'Lepton Photon' symposium, one of the well-established series of meetings in the high-energy physics community, was successfully organized at the South Campus of Sun Yat-sen University, Guangzhou, China, from August 7-12, 2017, where physicists around the world gathered to discuss the latest advancements in the research field.This proceedings volume of the Lepton Photon 2017 collects contributions by the plenary session speakers and the posters' presenters, which cover the latest results in particle physics, nuclear physics, astrophysics, cosmology, and plans for future facilities.

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 A Precision Measurement of Parity Violation in Moller Scattering

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 93 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-Q2 Moeller scattering. At tree level, A{sub PV} (expected to be around -150 ppb) is directly proportional to 1/4 - sin2 [theta]{sub W}. A precision measurement of A{sub PV} at low Q2 allows the running of sin2 [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 Q2 of 0.027 GeV2. 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 sin2 [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.

Book Observation of Parity Nonconservation in Moller Scattering

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).