Why the discrepancy in muonic H Bohr radius? 285 fm or 256 fm?

[seattle.truth]

Some places say (including this paper) claim the bohr radius of muonic hydrogen is 285http://ethesis.unifr.ch/theses/downloads.php?file=LudhovaL.pdf

Many more peer reviewed papers say it is 256 fm, or 255 fm though. (search for '256 fm muonic' in teh googlez).

So who is right? And more importantly, why is there such a massive descripancy?

Any help will be greatly appreciated. Thanks.

 

[fermi]

Some places say (including this paper) claim the bohr radius of muonic hydrogen is 285http://ethesis.unifr.ch/theses/downloads.php?file=LudhovaL.pdf

Many more peer reviewed papers say it is 256 fm, or 255 fm though. (search for '256 fm muonic' in teh googlez).

So who is right? And more importantly, why is there such a massive descripancy?

Any help will be greatly appreciated. Thanks.

They are both correct under different contexts. 256 fm is the correct Bohr radius for an infinitely heavy nucleus. 285fm is the Bohr radius for a proton-muon atom. This is because the reduced mass of muon when it forms an atom with a proton is 0.89879 times its rest mass. The first value is constant (but it is not accurate for a real system), while the second value is physical and accurate, but it is only valid for a proton nucleus. The physical value is different from 285 for a Deutoron for example (and it is in between 256 and 285, because the reduced muon mass is larger.)

 

[seattle.truth]

Thank you very much, sir.

I didn't know about reduced mass in Newtonian physics.

Now I'm enlightened (after doing a bit more research).

 

[Avodyne]

http://en.wikipedia.org/wiki/Reduced_mass