Tuning pythia for forward physics experiments

Abstract

Event generators like play an important role in physics studies at the Large Hadron Collider (LHC). While they make accurate predictions in the central region, i.e., at pseudorapidities <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>η</a:mi><a:mo>&lt;</a:mo><a:mn>5</a:mn></a:math>, a disagreement between and measurements in the forward region <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>η</c:mi><c:mo>&gt;</c:mo><c:mn>7</c:mn></c:math> has been observed. We introduce a dedicated forward physics tune for the event generator to be used for forward physics studies at the LHC, which uses a more flexible modeling of beam remnant hadronization and is tuned to available particle spectra measured by LHCf. Furthermore, we provide an uncertainty estimate on the new tune in a data-driven way which can be used as a means of flux uncertainty for future forward physics studies. We demonstrate an application of our tune by showing the updated neutrino and dark photon spectra at the FASER experiment. Published by the American Physical Society 2024