Paris NNbar Potential: G-parity & Unknown Particles

[quZz]

Hi, everyone!
There was a recent paper arXiv:0807.4454v2 [nucl-th] where authors present a revised version of Paris nucleon-antinucleon potential. I'm sure some of you have worked with it. In the region of distances r >~ 1 fm Paris NNbar potential is G-parity conjugation of the NN potential of their previous work - M. Lacombe et al Phys. Rev. C21, 861 (1980). In that article NN potential is presented as a sum of exponents g_k*exp(-m_k r)/(m_k r). But in the list of inverse compton wavelengths m_k I find m = 1.6 fm^(-1) that is the mass of 315.7 MeV. What is the corresponding particle and how I know its G-parity? There are several more unkown particles to me. On the other hand, I cannot find wavelengths corresponding to omega- and rho-mesons that I would expect to be in the list.
Could someone help to figure out G-parity transofrmation of NN potential?

 

[AndyW]

Hello there!

Thank you for bringing up this interesting paper. I have also worked with the Paris nucleon-antinucleon potential and am familiar with the previous work by M. Lacombe et al.

To answer your question, the particle corresponding to m = 1.6 fm^(-1) is the pion, which has a mass of approximately 315.7 MeV. The pion has a G-parity of -1, which means it is its own antiparticle.

As for the omega- and rho-mesons, they are not included in the list of inverse Compton wavelengths because they are not considered to be fundamental particles. They are instead composite particles made up of quarks and gluons.

The G-parity transformation of the NN potential can be found by considering the transformation properties of the individual terms in the potential. Since the potential is a sum of exponentials, the G-parity transformation will simply be the product of the G-parity of each term. In this case, since the pion has a G-parity of -1, the G-parity of the entire potential will also be -1.

I hope this helps clarify things for you. Let me know if you have any further questions or if you would like to discuss this topic further. Thank you for your contribution to the forum!

 

[sir-pinski]

Thank you for bringing this paper to our attention. The revised Paris NNbar potential is definitely an interesting topic to discuss. Regarding your question about the unknown particles and their G-parity, it is important to note that the Paris potential is based on a meson exchange model, where the nucleon-antinucleon interaction is mediated by the exchange of various mesons. These mesons have different masses and quantum numbers, and it is not always clear which particle corresponds to which value in the list of inverse compton wavelengths.

To answer your question about the mass of 315.7 MeV, this corresponds to the rho-meson. The rho-meson has a spin of 1, so its G-parity is positive. As for the omega-meson, it has a mass of 782 MeV and a spin of 0, so its G-parity is also positive. However, the omega-meson is not included in the list of inverse compton wavelengths because it does not contribute significantly to the NNbar potential at the distances considered in the paper.

In general, determining the G-parity transformation of the NN potential can be a complex task, as it involves taking into account the spin and isospin of the particles involved in the interaction. It is also important to note that the G-parity transformation of the NN potential is not unique, as it depends on the specific meson exchange model used.

I would recommend consulting with the authors of the paper or other experts in the field for a more detailed explanation of the G-parity transformation of the Paris NNbar potential. I hope this helps clarify some of your questions and further enriches your understanding of this interesting topic.