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Title: New Physics and the Proton Radius Problem

Abstract

Background: The recent disagreement between the proton charge radius extracted from Lamb shift measurements of muonic and electronic hydrogen invites speculation that new physics may be to blame. Several proposals have been made for new particles that account for both the Lamb shift and the muon anomalous moment discrepancies. Purpose: We explore the possibility that new particles' couplings to the muon can be fine-tuned to account for all experimental constraints. Method: We consider two fine-tuned models, the first involving new particles with scalar and pseudoscalar couplings, and the second involving new particles with vector and axial couplings. The couplings are constrained by the Lamb shift and muon magnetic moments measurements while mass constraints are obtained by kaon decay rate data. Results: For the scalar-pseudoscalar model, masses between 100 to 200 MeV are not allowed. For the vector model, masses below about 200 MeV are not allowed. The strength of the couplings for both models approach that of electrodynamics for particle masses of about 2 GeV. Conclusions: New physics with fine tuned couplings may be entertained as a possible explanation for the Lamb shift discrepancy.

Authors:
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1057558
Report Number(s):
JLAB-THY-12-1662; DOE/OR/23177-2404; arXiv:1206.3587
Journal ID: 1550-2368; NSF Grant PHY-0855618
DOE Contract Number:  
AC05-06OR23177
Resource Type:
Journal Article
Journal Name:
Phys.Rev. D
Additional Journal Information:
Journal Volume: 86; Journal Issue: 03
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Carl E. Carlson, Benjamin C. Rislow. New Physics and the Proton Radius Problem. United States: N. p., 2012. Web. doi:10.1103/PhysRevD.86.035013.
Carl E. Carlson, Benjamin C. Rislow. New Physics and the Proton Radius Problem. United States. doi:10.1103/PhysRevD.86.035013.
Carl E. Carlson, Benjamin C. Rislow. Wed . "New Physics and the Proton Radius Problem". United States. doi:10.1103/PhysRevD.86.035013.
@article{osti_1057558,
title = {New Physics and the Proton Radius Problem},
author = {Carl E. Carlson, Benjamin C. Rislow},
abstractNote = {Background: The recent disagreement between the proton charge radius extracted from Lamb shift measurements of muonic and electronic hydrogen invites speculation that new physics may be to blame. Several proposals have been made for new particles that account for both the Lamb shift and the muon anomalous moment discrepancies. Purpose: We explore the possibility that new particles' couplings to the muon can be fine-tuned to account for all experimental constraints. Method: We consider two fine-tuned models, the first involving new particles with scalar and pseudoscalar couplings, and the second involving new particles with vector and axial couplings. The couplings are constrained by the Lamb shift and muon magnetic moments measurements while mass constraints are obtained by kaon decay rate data. Results: For the scalar-pseudoscalar model, masses between 100 to 200 MeV are not allowed. For the vector model, masses below about 200 MeV are not allowed. The strength of the couplings for both models approach that of electrodynamics for particle masses of about 2 GeV. Conclusions: New physics with fine tuned couplings may be entertained as a possible explanation for the Lamb shift discrepancy.},
doi = {10.1103/PhysRevD.86.035013},
journal = {Phys.Rev. D},
number = 03,
volume = 86,
place = {United States},
year = {2012},
month = {8}
}