Two pT shifts enter this systematic :

1) Particle jets with UE=on -> Beyond leading order jets with UE=on

2) Beyond leading order jets with UE=on -> Beyond leading order jet with UE=off

These shifts go in opposite directions and are estimated in one fell swoop  for the final systematic. Figures 1A+1B show the absolute size of the combined shift and how it changes for quark and gluon jets.

Figure 1A:   R=0.4  2005 cuts                                                        Figure 1B:  R=0.7  2006 cuts

The total shift for R=0.4 is positive and this means you lose energy out of the particle cone and therefore would have to increase the particle jet pT to reflect this. Note the average shift here is ~4% which is what was quoted in the 2005 PRL.

The total shift for R=0.7 is negative for low pT and then goes very slightly positive for higher pT. At high pT this means we lose much less energy out of the cone due to fragmentation compared to the R=0.4 radius. At low pT this trend is reversed due to contributions from the UEon -> UE off shift.  I discussed in previous blogs that I believe this is due to splitting that occurs when the underlying event is turned on.

Figure 2:

Details of spectra which go into the correction for R=0.4 2005 cut jets

Figure 3:  R=0.7 2006 cuts