Quantum Gravity May Be Able To Resolve The Proton Radius Puzzle
A proton's official radius is 0.88±0.01 femtometers (fm, or 10-15m). Both hydrogen spectroscopy and electron scattering tests,
in which an electron beam is fired at a proton and the way the electrons scatter is used to quantify the proton's size, were
utilised by the researchers to arrive at that value.
The proton's quark structure
However, recently when scientists attempted to further increase the accuracy of the proton radius value using a third experimental technique,
they obtained a value of 0.842±0.001 fm, which was 7 deviations off from the official value. Instead of using atomic hydrogen,
which has an electron orbiting the proton, these tests used muonic hydrogen, in which a negatively charged muon orbits the proton.
A muon can more precisely estimate the proton size since it orbits a proton closer than an electron because it is 200 times heavier than an electron.
The "proton radius puzzle," which refers to this discrepancy between proton radius values, has received a lot of attention recently and numerous theories
have been put out. Some of these theories involve new, non-Standard Model degrees of freedom as well as additional dimensions.
Now, researchers at quantxcer have proposed that the muonic hydrogen experiment may be offering a hint of quantum gravity in a recent work
published in EPL. They have suggested that a novel theory of quantum gravity, commonly known as "gravitoweak unification,"
which is based on the unification of gravity and the weak force can be used to solve the proton radius conundrum.