View Full Version : Asymmetric fusion

2003-Apr-07, 03:53 PM
IU scientists first to detect rare nuclear fusion violating charge symmetry (http://www.spaceref.com/news/viewpr.html?pid=11174)

Is this the same asymmetry that results in there being more matter than antimatter, or is that something else entirely?

Kaptain K
2003-Apr-07, 04:51 PM
OK, admitting my ignorance here. :oops: How does the collision of two deuterium nuclei (1 proton+1 neutron each - total charge=+2) to form one helium nucleus and a neutral pion (2 protons+2 neutrons + pi 0 - total charge=+2) violate charge symmetry? :-?

Eta C
2003-Apr-07, 07:04 PM
My thought is that in the press release, the writer simplified things by omitting the somewhat more arcane concept of parity. What the process probably violates is Charge-Parity (or CP) symmetry. Parity inversions are similar to reflections. A process that obeys CP symmetry would look the same if all of the particles were changed to anti-particles and the entire reaction reflected (x to -x, y to -y). Processes that violate CP symmetry are rare as they are mediated by the weak nuclear force. Strong nuclear and electromagnetic processes all obey CP. I need to go back to my refs and see what the CP state of the two duterons and the final alpha and pi0 are. Haven't had to mess with that much since grad school.

Eta C
2003-Apr-17, 04:07 PM
Just found more info on this one. http://www.aip.org/enews/physnews/2003/split/633-2.html
It has nothing to do with CP symmetry. In nuclear reactions the proton and neutron should be indistinguisable since the stron nuclear force doesn't care what their electric charge is. What the experiment observes is a shift in the angular distribution of the pion that shouldn't occur if the charge symmetry were observed.