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Parity violating elastic electron-nucleus scattering provides an accurate and model independent measurement of neutron densities, because the $Z^0$ couples primarily to neutrons. Coulomb distortion corrections to the parity violating…

Nuclear Theory · Physics 2009-09-25 C. J. Horowitz

The parity-violating spin asymmetry Apv for elastic electron scattering from spin-zero nuclei, together with its QED corrections, is evaluated non-perturbatively within the phase-shift analysis. Dispersion corrections, taking into account…

Nuclear Theory · Physics 2026-03-30 D. H. Jakubassa-Amundsen , X. Roca-Maza

We present a new dispersive formulation of the gamma-Z box radiative corrections to weak charges of bound protons and neutrons in atomic parity violation (APV) measurements on heavy nuclei such as 133-Cs and 213-Ra. We evaluate for the…

High Energy Physics - Phenomenology · Physics 2013-11-26 P. G. Blunden , W. Melnitchouk , A. W. Thomas

We calculate the two-boson-exchange (TBE) corrections to the parity asymmetry of the elastic electron-proton scattering in a model using the formalism of generalized parton distributions (GPDs).

Nuclear Theory · Physics 2009-08-20 Yu Chun Chen , Chung Wen Kao

It has been suggested that two-photon exchange corrections could explain the discrepancy between Rosenbluth extractions of the proton form factors and recent polarization transfer measurements. We propose a precise comparison of…

The parity-violating longitudinal analyzing power, Az, has been measured in pp elastic scattering at an incident proton energy of 221 MeV. The result obtained is Az =(0.84 +/- 0.29 (stat.) +/- 0.17 (syst.)) x 10^{-7}. This experiment is…

Nuclear Experiment · Physics 2009-11-07 A. R. Berdoz , TRIUMF E497 Collaboration

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The kinematic point (theta_lab = 12.3 degrees and Q^2=0.48 (GeV/c)^2) is chosen to provide sensitivity, at a level…

Nuclear Experiment · Physics 2010-05-27 HAPPEX Collaboration , K. A. Aniol

Precision electroweak physics can provide fertile ground for uncovering new physics beyond the Standard Model (SM). One area in which new physics can appear is in so-called "oblique corrections", i.e., next-to-leading order expansions of…

High Energy Physics - Phenomenology · Physics 2015-03-17 Timothy Hobbs , Jonathan L. Rosner

Parity violating electron nucleus scattering is a clean and powerful tool for measuring the spatial distributions of neutrons in nuclei with unprecedented accuracy. Parity violation arises from the interference of electromagnetic and weak…

Nuclear Theory · Physics 2014-11-18 C. J. Horowitz , S. J. Pollock , P. A. Souder , R. Michaels

We review the progress made in the determination of the weak charge, Q\_w, of the cesium nucleus which raises the status of Atomic Parity Violation measurements to that of a precision electroweak test. Not only is it necessary to have a…

Atomic Physics · Physics 2016-08-16 Jocelyne Guéna , Michel Lintz , Marie-Anne Bouchiat

We apply a subtracted dispersion relation formalism with the aim to improve predictions for the two-photon exchange corrections to elastic electron-proton scattering observables at finite momentum transfers. We study the formalism on the…

High Energy Physics - Phenomenology · Physics 2016-01-29 O. Tomalak , M. Vanderhaeghen

We evaluate the two-photon exchange correction to the unpolarized cross section in the elastic muon-proton scattering within dispersion relations. One of the six independent invariant amplitudes requires a subtraction. We fix the…

High Energy Physics - Phenomenology · Physics 2024-10-28 Oleksandr Tomalak , Marc Vanderhaeghen

Systematic differences in the the proton's charge radius, as determined by ordinary atoms and muonic atoms, have caused a resurgence of interest in elastic lepton scattering measurements. The proton's charge radius, defined as the slope of…

A new analysis of parity violation in atomic cesium has led to the improved value of the weak charge, $Q_W({\rm Cs}) = -72.06 \pm 0.46$. The implications of this result for constraining the Peskin-Takeuchi parameters S and T and for guiding…

High Energy Physics - Phenomenology · Physics 2008-11-26 Jonathan L. Rosner

A forthcoming experiment of low-energy elastic electron proton scattering at the new MESA facility in Mainz is planned to provide a high-precision measurement of the parity-violating polarisation asymmetry. This experiment is expected to…

High Energy Physics - Phenomenology · Physics 2016-07-01 R. Bucoveanu , M. Gorchtein , H. Spiesberger

We report on a calculation of one-loop weak corrections to polarized quark-gluon scattering and the corresponding crossed channels. Such contributions are suppressed formally by one power of alpha_s relative to W- or Z-mediated quark-quark…

High Energy Physics - Phenomenology · Physics 2009-11-07 John Ellis , Stefano Moretti , Douglas Ross

We report the most precise measurement to date of a parity-violating asymmetry in elastic electron-proton scattering. The measurement was carried out with a beam energy of 3.03 GeV and a scattering angle <theta_lab>=6 degrees, with the…

Nuclear Experiment · Physics 2012-08-27 The HAPPEX Collaboration

We present the dispersion relation approach based on unitarity and analyticity to evaluate the two-photon exchange contribution to elastic electron-proton scattering. The leading elastic and first inelastic $\pi N$ intermediate state…

High Energy Physics - Phenomenology · Physics 2018-07-04 Oleksandr Tomalak

Measurement of the parity-violating electron scattering asymmetry from ${}^{208}$Pb has demonstrated a new opportunity at Jefferson Lab to measure the weak charge distribution and hence pin down the neutron radius in nuclei in a relatively…

Nuclear Experiment · Physics 2015-10-21 Robert Michaels