Explaining the Proton Radius Puzzle with Disformal Scalars

Abstract

We analyse the consequences of a disformal interaction between a massless scalar and matter particles in the context of atomic physics. We focus on the displacement of the atomic energy levels that it induces, and in particular the change in the Lamb shift between the 2s and 2p states. We find that the correction to the Lamb shift depends on the mass of the fermion orbiting around the nucleus, implying a larger effect for muonic atoms. Taking the cut-off scale describing the effective scalar field theory close to the QCD scale, we find that the disformal interaction can account for the observed difference in the proton radius of muonic versus electronic Hydrogen. Explaining the proton radius puzzle is only possible when the scalar field is embedded in non-linear theories which alleviate constraints from collider and stellar physics. Short distance properties of the Galileon where non-perturbative effects in vacuum are present ensure that unitarity is preserved in high energy particle collisions. In matter, the chameleon mechanism alleviates the constraints on disformal interactions coming from the burning rates for stellar objects. We show how to combine these two properties in a single model which renders the proposed explanation of the proton radius puzzle viable.

arXiv comment17 pages, typos corrected and references added

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Cited by in corpus (18)

• Disformal Theories of Gravity: From the Solar System to Cosmology
• Relativistic stars in scalar-tensor theories with disformal coupling
• Cosmological disformal invariance
• Disformal Gravity Theories: A Jordan Frame Analysis
• Disformal dark energy at colliders
• Solar System Constraints on Disformal Gravity Theories
• Probing new physics using Rydberg states of atomic hydrogen
• Experiments towards resolving the proton charge radius puzzle
• K-mouflage effects on clusters of galaxies
• Is the proton radius puzzle evidence of extra dimensions?
• Deuterium spectroscopy for enhanced bounds on physics beyond the Standard Model
• Can Galileons solve the muon problem?
• Reduced Theoretical Error for QED Tests with 4He+ Spectroscopy
• More about scalar gravity
• Stars disformally coupled to a shift-symmetric scalar field
• Standard Electroweak Interactions in Gravitational Theory with Chameleon Field and Torsion
• Applying Bayesian Inference to Galileon Solutions of the Muon Problem
• The Muon Experimental Anomalies Are Explained by a New Interaction Proportional to Charge