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Measurement of the differential cross sections for isolated direct photon pair production in pp collisions at

Research output: Contribution to Journal/MagazineJournal articlepeer-review

<mark>Journal publication date</mark>9/08/2013
<mark>Journal</mark>Physics Letters B
Issue number1-3
Number of pages9
Pages (from-to)6-14
Publication StatusPublished
<mark>Original language</mark>English


We present measurements of direct photon pair production cross sections using 8.5 fb−1 of data collected with the D0 detector at the Fermilab Tevatron collider. The results are presented as differential distributions of the photon pair invariant mass dσ/dMγγ, pair transverse momentum , azimuthal angle between the photons dσ/dΔϕγγ, and polar scattering angle in the Collins–Soper frame . Measurements are performed for isolated photons with transverse momenta for the leading (next-to-leading) photon in pT, pseudorapidities |ηγ|<0.9, and a separation in η–ϕ space ΔRγγ>0.4. We present comparisons with the predictions from Monte Carlo event generators diphox and resbos implementing QCD calculations at next-to-leading order, 2γnnlo at next-to-next-to-leading order, and sherpa using matrix elements with higher-order real emissions matched to parton shower.