b-jet shape analysis using Monte Carlo methods

My MSci degree thesis.


Luke Pomfrey


The accuracy of Monte Carlo simulations in describing the shape of b-quark jets has been investigated before. Here, this is investigated more closely, comparing several tunes of pythia6 and also herwig and jimmy. Jets with transverse momentum in the range 52 to 300 $\text{GeV}/c$ are investigated, and the experimental data used is from the upgraded Collider Detector at Fermilab (CDF II) in pp collisions at a centre of mass energy $\sqrt{s} = 1.96$ TeV. The effect of the simulated quark masses in pythia6 are also investigated, and a tune of pythia6 attempted.

The results confirm the previous conclusion, that the jets produced in Monte Carlo simulations are too narrow. It can also be seen that the quark masses in pythia6 are not a factor in determining the b-jet shape. It is shown that by increasing the amount of b-quarks pythia6 produce in parton showers a better result is obtained.


L. Pomfrey. b-jet shape analysis using Monte Carlo methods. March, 2009. http://lukepomfrey.org/masters-thesis/