Analyzing Lam-Tung Relation Violation Using Soft Gluon Resummation
Session Number
3
Advisor(s)
Dr. Paul Reimer, Argonne National Laboratory
Location
A113
Discipline
Physical Science
Start Date
15-4-2026 2:15 PM
End Date
15-4-2026 3:00 PM
Abstract
The internal structure of the proton is impossible to directly probe using traditional methods. Indirect methods, primarily observing the proton’s interactions with other particles, are used instead. One of the most common such methods is the Drell-Yan (DY) process. In this interaction, two hadrons collide, and a quark from one hadron and an antiquark from the other annihilate into a virtual photon. The virtual photon instantly decays into two leptons that can be analyzed to determine the cross-section of the DY process. The cross section can be theoretically calculated using empirically determined Parton Distribution Functions. One component of the DY cross section is the angular distribution of the dimuons in the Collins-Soper frame. In this frame, the angular contributions to the DY cross-section are constrained by the Lam-Tung relation. This relation holds for leading order calculations, but experiments show that the Lam-Tung relation is violated. However, calculations at higher order are still in agreement with Lam-Tung. We aim to apply soft gluon resummation (SGR) to theoretical calculations of DY to determine if including SGR resolves the discrepancy between theoretical and experimental results. SGR considers the large contributions to the DY cross-section made by the release of low transverse momentum gluons.
Analyzing Lam-Tung Relation Violation Using Soft Gluon Resummation
A113
The internal structure of the proton is impossible to directly probe using traditional methods. Indirect methods, primarily observing the proton’s interactions with other particles, are used instead. One of the most common such methods is the Drell-Yan (DY) process. In this interaction, two hadrons collide, and a quark from one hadron and an antiquark from the other annihilate into a virtual photon. The virtual photon instantly decays into two leptons that can be analyzed to determine the cross-section of the DY process. The cross section can be theoretically calculated using empirically determined Parton Distribution Functions. One component of the DY cross section is the angular distribution of the dimuons in the Collins-Soper frame. In this frame, the angular contributions to the DY cross-section are constrained by the Lam-Tung relation. This relation holds for leading order calculations, but experiments show that the Lam-Tung relation is violated. However, calculations at higher order are still in agreement with Lam-Tung. We aim to apply soft gluon resummation (SGR) to theoretical calculations of DY to determine if including SGR resolves the discrepancy between theoretical and experimental results. SGR considers the large contributions to the DY cross-section made by the release of low transverse momentum gluons.