Off-shell transport

Testing off-shell transport

To test the off-shell transport we propagate a particle, being represented by 200.000 test-particles, through space and time. The collision term is being switched off - therefore, there is just the propagation due to mean fields and the off-shell potential based on the momentum and position dependend width of the particle.

While we choose the position and momentum of all test-particles to be the same at the initial time, the masses are distributed according to the spectral function which depends on the initial momentum and position. We consider six different initial conditions:

1. A nucleon is initialized with momentum 0.5 GeV at the center of a Calcium nucleus.	(job card)
2. A nucleon is initialized with momentum 1.5 GeV at the center of a Calcium nucleus.	(job card)
3. A Delta is initialized with momentum 0.5 GeV at the center of a Calcium nucleus.	(job card)
4. A Delta is initialized with momentum 1.5 GeV at the center of a Calcium nucleus.	(job card)
5. A Delta is initialized with momentum (0.5,0,0) GeV at (-8,1,0) in front of a Calcium nucleus.	(job card)
6. A Delta is initialized with momentum (1.5,0,0) GeV at (-8,1,0) in front of a Calcium nucleus.	(job card)

For the initial conditions 1-2 we expect that the nucleon propagates to its on-shell value of 0.938 GeV, while for the initial conditions 3-4 we expect just a less broad mass disribution of the test-particles at the end of the propagation. Finally, for initial conditions 5-6 we expect the spectral function to be the same after the propagation through the nucleus as the initial ones. The final results for each initial condition is shown in figures 1-6. The left plot shows the distribution of the test-particles as function of its mass and absolute position, i.e. the radius. And the right one shows just the distribution according to its mass. From those figures we conclude that our expectations are very well fulfilled and that besides some numerical noise the off-shell transport seems to work properly.

Figure 1

A nucleon with 0.5 GeV momentum is propagating from the center of a Calcium nucleus outwards.

Figure 2

A nucleon with 1.5 GeV momentum is propagating from the center of a Calcium nucleus outwards.

Figure 3

A Delta with 0.5 GeV momentum is propagating from the center of a Calcium nucleus outwards.

Figure 4

A Delta with 1.5 GeV momentum is propagating from the center of a Calcium nucleus outwards.

Figure 5

A Delta with 0.5 GeV momentum is propagating through a Calcium nucleus.

Figure 6

A Delta with 1.5 GeV momentum is propagating through a Calcium nucleus.