Speaker
Ioannis Polychronakos
(Lund University)
Description
The quarks and gluons inside a proton are expected to have an intrinsic momentum proportional to $\Lambda_{QCD}$ due to Fermi motion. In Monte Carlo event generators, primordial $k_T$ acts as an effective parameter that absorbs a broader range of unresolved physics, such as soft emissions below the parton shower cut-off. We present the evolution of the primordial $k_T$ width as a function of the hard scattering scale ($Q$) and the center of mass energy ($\sqrt{s}$) extracted by systematically tuning it to Drell-Yan dilepton production data. We demonstrate the need for a new parametrization for primordial $k_T$ and take steps towards a new global and more principled tune for PYTHIA 8.
Author
Ioannis Polychronakos
(Lund University)
Co-author
Christian Bierlich
(Lund University (SE))