Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at $$\sqrt{s}=7\,\text {TeV} $$ s = 7 TeV

Abstract

A measurement of differential cross sections for the production of a pair of isolated photons in proton–proton collisions at is presented. The data sample corresponds to an integrated luminosity of 5.0 collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25 respectively, in the pseudorapidity range , and with an angular separation , is . Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins–Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.

GR@PPA 2.9: Radiation matching for simulating photon production processes in hadron collisions

“…Furthermore, it was recently found that the next-to-next-to-leading order (NNLO) correction that includes the effects of associated two-parton production is also large, as in the direct photon production [15,16]. Hence, this order of correction is necessary to be included in order to realistically reproduce the non-resonant diphoton production [17,18], although we still do not have any reasonable explanation on this large correction. Here, we note that the large NNLO correction is not predominantly caused by the emergence of new processes, e.g., gg → γγqq, but mainly originates from ordinary gluon-radiation corrections to one-parton production processes [15].…”

Photon pair production in gluon fusion: top quark effects at NLO with threshold matching

“…We do not include resummation effects in the real-radiation because it is suppressed by a factor of β. The M (0) OC and M (1) OC (µ) denote the LO and NLO double-counted part of the amplitude as we discussed above. Note that the explicit dependence of M OC to respectively O(β 3 ) and O(β 2 ) using the expressions stated in Section 3.1.…”

“…The production of pairs of photons in hadronic collisions has attracted interest from both the experimental and the theory side for several decades. Most prominently, the diphoton final state served as one of the key discovery channels for the Higgs boson [1,2], which can decay into two photons. As a very clean experimental channel, it is also well suited for precision studies of the Standard Model (SM) and in particular the Higgs sector.…”

“…Another interesting aspect of diphoton production is the possibility of measuring the top quark mass via the top quark pair production threshold effects manifest in the diphoton invariant mass spectrum [13,14]. While current LHC measurements [1,2] are not yet able to provide the necessary statistics for such a threshold scan, the feasibility at the High-Luminosity LHC, and even more so at a future 100 TeV collider, is worth investigating.…”

Electroweak corrections to diphoton plus jets

“…It played an essential role in the discovery of the Higgs boson [1,2] and in further refined measurements of fiducial cross sections and differential observables [3][4][5][6][7]. Due to its clean experimental signal, diphoton production in hadron collisions offers a testing ground for perturbative quantum chromodynamics and has been widely studied at the LHC [8][9][10][11][12]. This process is also an important search channel for new physics (see [13][14][15][16][17][18][19][20] for recent experimental searches).…”