Measurements of triple-differential cross sections for inclusive isolated-photon+jet events in p p collisions at s = 8 TeV

Abstract

Measurements are presented of the triple-differential cross section for inclusive isolated-photon+jet events in $pp$ collisions at $\sqrt{s}=8$ TeV as a function of photon transverse momentum ( $p_T^{\gamma }$ ), photon pseudorapidity ( ${\eta }^{\gamma }$ ), and jet pseudorapidity ( ${\eta }^{\text{jet}}$ ). The data correspond to an integrated luminosity of $19.7{\text{fb}}^{-1}$ that probe a broad range of the available phase space, for $|{\eta }^{\gamma }|<1.44$ and $1.57<|{\eta }^{\gamma }|<2.50$ , $|{\eta }^{\text{jet}}|<2.5$ , $40<p_T^{\gamma }<1000$ $\text{GeV}$ , and jet transverse momentum, $p_T^{\text{jet}}$ , > 25 $\text{GeV}$ . The measurements are compared to next-to-leading order perturbative quantum chromodynamics calculations, which reproduce the data within uncertainties.

Fig. 1

An example fit of candidate boosted-decision-tree distribution with a composite template (blue histogram). The signal (background) template is shown by the green (red) solid (hatched) region. The bottom panel shows the mean of the fit values for 500 templates varied within the signal and background shape uncertainties (F) subtracted from data (D) divided by the data

Fig. 2

Purity estimates as a function of $p_{\mathrm{T}}^{\mathrm{\gamma }}$ for different photon and jet pseudorapidity regions. The values are offset by 0.3, 0.6 and 0.9 for $0.8<|{\eta }^{\text{jet}}|<1.5$, $1.5<|{\eta }^{\text{jet}}|<2.1$, and $2.1<|{\eta }^{\text{jet}}|<2.5$ respectively. The total uncertainties are shown as error bars

Fig. 3

Measured triple-differential cross section distributions as a function of $p_{\mathrm{T}}^{\mathrm{\gamma }}$ in different bins of $|{\eta }^{\text{jet}}|$ for photons in the barrel region. Note that the distributions are multiplied by a factor of ${10}^2$, ${10}^4$ and ${10}^6$ for $0.8<|{\eta }^{\text{jet}}|<1.5$, $1.5<|{\eta }^{\text{jet}}|<2.1$, and $2.1<|{\eta }^{\text{jet}}|<2.5$ respectively. The statistical (systematic) uncertainties are shown as error bars (color bands)

Fig. 4

Measured triple-differential cross section distributions as a function of $p_{\mathrm{T}}^{\mathrm{\gamma }}$ in different bins of $|{\eta }^{\text{jet}}|$ for photons in the endcap region. Note that the distributions are multiplied by a factor of ${10}^2$, ${10}^4$ and ${10}^6$ for $0.8<|{\eta }^{\text{jet}}|<1.5$, $1.5<|{\eta }^{\text{jet}}|<2.1$, and $2.1<|{\eta }^{\text{jet}}|<2.5$ respectively. The statistical (systematic) uncertainties are shown as error bars (color bands)

Fig. 5

Ratio of triple-differential cross sections as a function of $p_{\mathrm{T}}^{\mathrm{\gamma }}$ measured in data over the corresponding GamJet NLO theoretical prediction (obtained with the CJ15 PDFs) in different bins of $|{\eta }^{\text{jet}}|$ for $|{\eta }^{\mathrm{\gamma }}|<0.8$. Error bars on the data are statistical uncertainties, and blue bands represent the systematic uncertainties

Fig. 6

Ratio of triple-differential cross sections as a function of $p_{\mathrm{T}}^{\mathrm{\gamma }}$ measured in data over the corresponding GamJet NLO theoretical prediction (obtained with the CJ15 PDFs) in different bins of $|{\eta }^{\text{jet}}|$ for $0.80<|{\eta }^{\mathrm{\gamma }}|<1.44$. Error bars on the data are statistical uncertainties, and blue bands represent the systematic uncertainties

Fig. 7

Ratio of triple-differential cross sections as a function of $p_{\mathrm{T}}^{\mathrm{\gamma }}$ measured in data over the corresponding GamJet NLO theoretical prediction (obtained with the CJ15 PDFs) in different bins of $|{\eta }^{\text{jet}}|$ for $1.56<|{\eta }^{\mathrm{\gamma }}|<2.10$. Error bars on the data are statistical uncertainties, and blue bands represent the systematic uncertainties

Fig. 8

Ratio of triple-differential cross sections as a function of $p_{\mathrm{T}}^{\mathrm{\gamma }}$ measured in data over the corresponding GamJet NLO theoretical prediction (obtained with the CJ15 PDFs) in different bins of $|{\eta }^{\text{jet}}|$ for $2.1<|{\eta }^{\mathrm{\gamma }}|<2.5$. Error bars on the data are statistical uncertainties, and blue bands represent the systematic uncertainties