Triphoton production at hadron colliders in NNLO QCD

Abstract

We present next-to-next-to-leading-order (NNLO) QCD corrections to the production of three isolated photons in hadronic collisions at the fully differential level. We employ qT subtraction within MATRIX and an efficient implementation of analytic two-loop amplitudes in the leading-colour approximation to achieve the first on-the-fly calculation for this process at NNLO accuracy. Numerical results are presented for proton-proton collisions at energies ranging from 7 TeV to 100 TeV. We find full agreement with the 8 TeV results of arXiv:1911.00479 and confirm that NNLO corrections are indispensable to describe ATLAS 8 TeV data. In addition, we demonstrate the significance of NNLO corrections for future precision studies of triphoton production at higher collision energies.

Figures (8)

• Figure 1: Feynman diagrams for the production of three isolated photons: (a) LO diagram in the quark-annihilation channel; (b) vanishing loop-induced diagram in the gluon-fusion channel; (c,d) first non-vanishing loop-induced contributions. Closed quark loops are included for all massive and massless flavours here, i.e. $q'=d,u,s,c,b,t$.
• Figure 2: Dependence of the NNLO cross section for $pp\rightarrow \gamma\gamma\gamma+X$ on the slicing parameter $r_{\mathrm{cut}}$ (red points with numerical error bars), the extrapolated cross section for $r_{\mathrm{cut}}\rightarrow0$ (orange, solid) and comparison to the results from Ref. Chawdhry:2019bji (blue, dashed).
• Figure 3: Impact of different contributions to the two-loop hard function of the $u\bar{u}\rightarrow \gamma\gamma$ process as functions of the (dimensionless) momentum transfer. The main frame shows the leading-colour approximation $H^{(2,0)}$, a separate curve for the combination of $H^{(2,0)}$ with each of the three subleading corrections in Eq. (\ref{['eq:h2contributions']}), and the full result. The lower frame shows the relative differences with respect to $H^{(2,0)}$.
• Figure 4: Fiducial cross sections for $pp\rightarrow \gamma\gamma\gamma+X$ as a function of the centre-of-mass energy at LO (black dotted), at NLO (red dashed), and at NNLO (blue, solid) The green data point at 8 TeV corresponds to the cross section measured by ATLAS in Ref. Aaboud:2017lxm.
• Figure 5: Invariant-mass distribution of the three-photon system (top left plot) and of each photon pair compared to 8 TeV ATLAS data Aaboud:2017lxm. The colour coding corresponds to Figure \ref{['fig:cs']}.