How strange is pion electroproduction?

Gorchtein, Mikhail; Spiesberger, Hubert; Zhang, Xilin

doi:10.1016/j.physletb.2015.11.038

Title: How strange is pion electroproduction?

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Abstract

We consider pion production in parity-violating electron scattering (PVES) in the presence of nucleon strangeness in the framework of partial wave analysis with unitarity. Using the experimental bounds on the strange form factors obtained in elastic PVES, we study the sensitivity of the parity-violating asymmetry to strange nucleon form factors. For forward kinematics and electron energies above 1 GeV, we observe that this sensitivity may reach about 20% in the threshold region. With parity-violating asymmetries being as large as tens p.p.m., this study suggests that threshold pion production in PVES can be used as a promising way to better constrain strangeness contributions. Using this model for the neutral current pion production, we update the estimate for the dispersive γZ-box correction to the weak charge of the proton. In the kinematics of the Qweak experiment, our new prediction reads Re^V_γZ(E = 1.165 GeV) = (5.58 ±1.41) ×10^–3, an improvement over the previous uncertainty estimate of ±2.0 ×10^–3. Our new prediction in the kinematics of the upcoming MESA/P2 experiment reads Re^V_γZ(E = 0.155 GeV) = (1.1 ±0.2) ×10^–3.

Authors:: Gorchtein, Mikhail; Spiesberger, Hubert; Zhang, Xilin

Publication Date:: Fri Jan 01 00:00:00 EST 2016

Research Org.:: Univ. of Washington, Seattle, WA (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1226388

Alternate Identifier(s):: OSTI ID: 1238794

Grant/Contract Number:: FG02-97ER-41014; FG02-97ER41014

Resource Type:: Published Article

Journal Name:: Physics Letters B

Additional Journal Information:: Journal Name: Physics Letters B Journal Volume: 752 Journal Issue: C; Journal ID: ISSN 0370-2693

Publisher:: Elsevier

Country of Publication:: Netherlands

Language:: English

Subject:: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats


                    Gorchtein, Mikhail, Spiesberger, Hubert, and Zhang, Xilin. How strange is pion electroproduction?.  Netherlands: N. p., 2016. 
Web.  doi:10.1016/j.physletb.2015.11.038.

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                    Gorchtein, Mikhail, Spiesberger, Hubert, & Zhang, Xilin. How strange is pion electroproduction?.  Netherlands.  https://doi.org/10.1016/j.physletb.2015.11.038

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                    Gorchtein, Mikhail, Spiesberger, Hubert, and Zhang, Xilin. Fri .  
"How strange is pion electroproduction?".  Netherlands.  https://doi.org/10.1016/j.physletb.2015.11.038.

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@article{osti_1226388,

  title        = {How strange is pion electroproduction?},

  author       = {Gorchtein, Mikhail and Spiesberger, Hubert and Zhang, Xilin},

  abstractNote = {We consider pion production in parity-violating electron scattering (PVES) in the presence of nucleon strangeness in the framework of partial wave analysis with unitarity. Using the experimental bounds on the strange form factors obtained in elastic PVES, we study the sensitivity of the parity-violating asymmetry to strange nucleon form factors. For forward kinematics and electron energies above 1 GeV, we observe that this sensitivity may reach about 20% in the threshold region. With parity-violating asymmetries being as large as tens p.p.m., this study suggests that threshold pion production in PVES can be used as a promising way to better constrain strangeness contributions. Using this model for the neutral current pion production, we update the estimate for the dispersive γZ-box correction to the weak charge of the proton. In the kinematics of the Qweak experiment, our new prediction reads ReVγZ(E = 1.165 GeV) = (5.58 ±1.41) ×10–3, an improvement over the previous uncertainty estimate of ±2.0 ×10–3. Our new prediction in the kinematics of the upcoming MESA/P2 experiment reads ReVγZ(E = 0.155 GeV) = (1.1 ±0.2) ×10–3.},

  doi          = {10.1016/j.physletb.2015.11.038},

  journal      = {Physics Letters B},

  number       = C,

  volume       = 752,

  place        = {Netherlands},

  year         = {Fri Jan 01 00:00:00 EST 2016},

  month        = {Fri Jan 01 00:00:00 EST 2016}

}

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