Speaker
Description
In ultra-relativistic heavy-ion collisions, large rates of γγ processes arise from the intense electromagnetic fields generated by the colliding nuclei. These γγ interactions provide a powerful laboratory to study reactions that may be sensitive to physics beyond the Standard Model.
This talk presents the first differential fiducial measurements of γγ→τ+τ− production using 1.93 nb$^{−1}$ of Pb+Pb data at $\sqrt{s_{NN}}$=5.02 TeV recorded by ATLAS. Events where both nuclei remain intact and no neutrons are emitted are used for the analysis.
Differential cross-sections are measured for seven observables in three fiducial regions and compared with state-of-the-art theoretical predictions. The data are also used to constrain the electromagnetic properties of the τ-lepton through a fit to the muon transverse-momentum spectrum. The resulting 95% confidence level intervals are −0.057<a_τ<0.035 and ∣d_τ∣<2.7×10−16 e cm providing the first heavy-ion constraint on the τ-lepton electric dipole moment.
| Is this an experimental talk? | Yes |
|---|---|
| Is this on behalf of a collaboration? | Yes |
| Which collaboration? | ATLAS |
| Are you willing to present as a poster if it is not selected for oral presentation? | Yes |