All-orders resummation for diphoton production at hadron colliders

Abstract

We present a QCD calculation of the transverse momentum distribution of photon pairs produced at hadron colliders, including all-orders soft-gluon resummation valid at next-to-next-to-leading logarithmic accuracy. We specify the region of phase space in which the calculation is most reliable, compare our results with data from the Fermilab Tevatron, and make predictions for the Large Hadron Collider. The uncertainty of predictions for production of diphotons from fragmentation of final-state quarks is examined.

Figures (3)

• Figure 1: (a) Invariant mass and (b) transverse momentum distributions of diphotons. Data from the CDF Run-2 measurement Acosta:2004sn are compared to our calculation (RESBOS) and the DIPHOX calculation.
• Figure 2: (a) Distribution over the azimuthal separation $\Delta\varphi$ between the two photons. Data from the CDF Run-2 measurement Acosta:2004sn are compared with our calculation (RESBOS) and the DIPHOX calculation for different isolation parameters; (b) same as (a), with an additional cut $Q_{T}<Q$ on the diphoton momentum. Our cross sections are evaluated with the factorization scales $\mu_{F}=Q$ (lower curve) and 0.5 $Q$ (upper curve) in the finite-order contribution.
• Figure 3: Resummed transverse momentum distributions of photon pairs in various $\gamma \gamma$ invariant mass ($Q$) bins at (a) the Tevatron and (b) the LHC. The curves are calculated with the cuts specified in the text. The cross sections are normalized to the total cross section in each bin of $Q$. We note that our predictions are most reliable in the region $Q_T < Q$, but we plot the curves over the full range of $Q_T$, using the procedure described in the text to switch from the resummed to the finite-order perturbative results for $Q_T > Q$.