Non-central nature of nuclear force?

[Reshma]

Nuclear forces are said to be non-central. By definition of central force, angular momentum is constant. It is usually found in spherical bodies. How do the electric quadruple moments indicate the non-spherical structure of the nucleus? How is the nucleus stable if the angular momentum is not constant?

 

[Reshma]

Hello? Can someone help me here?

 

[marlon]

How do the electric quadruple moments indicate the non-spherical structure of the nucleus?

Based upon the sign of the electric quadrupolemoment, you know the shape of the charge distribution around the nucleus. It kind of expresses the electrical dipole you have because of a non-sferical structure (like oblate/prolate-ellipsoids)

Quadrupole moment

marlon

 

[Haelfix]

Take classical Yukawa theory, and expand it. Its pretty clear that its not a central potential.

 

[reilly]

Haelfix -- not for the usual scalar interation often used to explain the Yukawa potential. For nucleons and pions. The interaction includes "gamma5". Pions have negative parity, the gamma5 allows parity to be conserved, and provides a spin-dependent interaction.
Regards,
Reilly Atkinson

 

[Haelfix]

Yea I realized I misworded my response pretty badly.

The Yukawa potential *is* a central potential, but to see why the nuclear force is *not* it more or less suffices to look at the former and see where it must break down.

Qualitatively in Nuclear physics in many reactions you will get some small angular momentum state mixing that will depart from the Yukawa potential. Typically what is done is you add in these error terms and build a model around it by comparing to experiment. So for instance in pion exchange models you will get a central potential term like the Yukawa force (or Woods Saxon form) and something tensor like. From there its all phenomonology.