shrinking proton.

[sunshaker]

Just wanted to ask a question, old news, but from what I gather the proton is 4% smaller than previously thought,

I was wondering would this make any difference to how we calculate the protons mass?

 

Speaking today (April 13) at the April meeting of the American Physical Society, researchers said they need more data to understand why new measurements of proton size don't match old ones.

"The discrepancy is rather severe," said Randolf Pohl, a scientist at the Max Planck Institute of Quantum Optics. The question, Pohl and his colleagues said, is whether the explanation is a boring one — someone messed up the measurements — or something that will generate new physics theories.http://www.livescience.com/28707-shrinking-proton-puzzle-new-experiments.html

 

[swansont]

Mass? No. Size and mass are different things.

 

Also, we're not sure which measurement is correct

[Strange]

It is not that it is smaller than previously thought, but using a different way of measuring it gives a different (and unexpected) value. Previous measurements were done using electrons, the measurements in this article used muons. As the article says, there are several possible explanations. The most likely (?) is that QED, despite its success, is "wrong". But as we have very few clues as to what a better model would be ...

 

 

I was wondering would this make any difference to how we calculate the protons mass?

 

I can't see why.

 

"One way to measure the mass, say, of a proton, is to put it in a mass spectrometer. Accelerating it in a known electric field gives it an amount of kinetic energy proportional to its charge. Causing the proton to move in a circular path in a uniform, well-calibrated magnetic field allows the momentum to be measured quite precisely."

https://van.physics.illinois.edu/qa/listing.php?id=1209

[truedeity]

Mass is calculated using electron volts as its units. In the case of proton/neutron/electron its (Megaelectron volts), so mass is not related with size its related with energy content. Below are masses of the bunch-

Neutron = 939.56563 MeV
Proton = 938.27231 MeV
Electron = 0.51099906 MeV

[MigL]

Given that a proton is essentially a 'bag' containing three possibly dimensionless ( or close to it ) fundamental particles, scattering experiments or orbital determination would only have established a maximum size or extent.

 

And as there are going to be interactions at extremely close range between quarks and electrons/muons ( they all have charge ), I would think the measuring particle may affect the 'size' of the measured composite particle.

[swansont]

Given that a proton is essentially a 'bag' containing three possibly dimensionless ( or close to it ) fundamental particles, scattering experiments or orbital determination would only have established a maximum size or extent.

 

And as there are going to be interactions at extremely close range between quarks and electrons/muons ( they all have charge ), I would think the measuring particle may affect the 'size' of the measured composite particle.

But the physics that might explain this is lacking in some way. The different measurements + theory are something like seven sigma apart