Sub-GeV $U(1{)}_R$ gauge boson to address the proton radius discrepancy

Abstract

We propose a Standard Model extension by a $U(1{)}_R$ gauge symmetry where only right-handed chiral fermions can carry a non-trivial charge. Here we show that the simplest anomaly-free solution to accommodate the proton charge radius discrepancy takes right-handed muons ${\mu }_R$ and first generation quarks, $u_R$ and $d_R$. Consistency with the latest muon's $(g-2)$ measurements is achieved through an extra light scalar, which itself must lie in the tens of MeV mass range to be viable.

14 pages, 6 figures, 2 tables. v2: typos corrected, references added. Matches published version in PRD

References in corpus (11)

• Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
• Test of lepton universality in beauty-quark decays
• The Proton Radius Puzzle
• The proton charge radius
• New Parity-Violating Muonic Forces
• Magnetic Field Measurement and Analysis for the Muon g-2 Experiment at Fermilab
• The light U boson as the mediator of a new force, coupled to a combination of Q, B, L and dark matter
• New Physics in Rare B Decays after Moriond 2021
• The anomalous magnetic moment of the muon: status of Lattice QCD calculations
• On the Flavour Structure of Anomaly-free Hidden Photon Models
• Probing the flavor-specific scalar mediator for the muon $(g-2)$ deviation, the proton radius puzzle and the light dark matter production

Cited by in corpus (1)

• Chiral $Z^{\prime }$ in FASER, FASER2, DUNE, and ILC beam dump experiments