level 7
能联系到cp破缺，具体不懂
直接ISI里搜Upsilon(4S)吧
2012年02月16日 15点02分
level 1
level 8
I'm no expert on this, so I can only make some guesses.
The parton here may probably be referred to as the propagator,
which by definition is an off-shell (virtual) particle.
So, you can express the 4-momentum of this virtual particle as , e.g (E,P)
and calculate Q^2 = E^2 - P^2. (I guess the sign convention is like this here,
the other being -E^2 +P^2 ).
If Q^2 = 0, it might be called "null", just as ds^2 = 0 in special relativity.
If Q^2 >> 0, it might be called "highly time-like".
If Q^2 << 0 , it might refer to "highly space-like". ...
2012年03月13日 21点03分
8
The parton here may probably be referred to as the propagator,
which by definition is an off-shell (virtual) particle.
So, you can express the 4-momentum of this virtual particle as , e.g (E,P)
and calculate Q^2 = E^2 - P^2. (I guess the sign convention is like this here,
the other being -E^2 +P^2 ).
If Q^2 = 0, it might be called "null", just as ds^2 = 0 in special relativity.
If Q^2 >> 0, it might be called "highly time-like".
If Q^2 << 0 , it might refer to "highly space-like". ...
