Speaker
Description
The proton radius puzzle began in 2010 when the CREMA Collaboration released their measurement of the proton radius (Pohl et. al (2010)) from muonic hydrogen spectroscopy: rp=0.84184(67) fm, This was five standard deviations smaller that the accepted CODATA value at that time (0.8768(69) fm), and sparked an enduring and intriguing puzzle. This puzzle has been addressed in repeated electron scattering measurements seeking to go lower in Q2, such as PRad at Jefferson Lab, and the Mainz Initial State Radiation experiment. There has also been a plethora of new atomic hydrogen spectroscopy experiments, and some more muonic atom spectroscopy. The results of these measurements have served to further add to the puzzle, with even CODATA saying that more and different measurements are needed. New experiments are planned and underway which seek to address this challenge in new ways. We will summarize the current status and future outlook of proton radius investigations.
