Search for $W$ and $Z$ bosons in the reaction $\overline{p}p\to \mathrm{two}\mathrm{jets}+\gamma$ at $\sqrt{s}=1.8\mathrm{TeV}$

We present a study of the dijet invariant mass distribution for the reaction $\overline{p}p\to \mathrm{two}\mathrm{jets}+\gamma +X$, at a center of mass energy of 1.8 TeV, using data collected by the CDF experiment. We compare the data to predictions for the production of a photon with two jets, together with the resonant processes $\overline{p}p\to W/Z+\gamma +X$, in which the $W$ and $Z$ bosons decay hadronically. A fit is made to the dijet invariant mass distribution combining the nonresonant background and resonant processes. We use the result to establish a limit for the inclusive production cross section of $W/Z+\gamma$ with hadronic decay of the $W$ and $Z$ bosons.

Figure 1

Photon $E_T$ distribution from $\gamma +\mathrm{two}\mathrm{\text{−}}\mathrm{jet}$ events.

Figure 2

The $E_T$ and $\eta$ distributions for the two leading jets.

Figure 3

Dijet mass spectrum from $\mathrm{two}\mathrm{\text{−}}\mathrm{jet}+\gamma$ data. There are 2656 events in the $m_{jj}$ region from 60 to $126\mathrm{GeV}/c^2$. The solid fit corresponds to the background $+$ signal fit as described in Sec. 6.

Figure 4

The invariant mass distributions of the two leading jets from the LO $W\gamma$ and $Z\gamma$ simulations, together with their sum (solid line). The combined invariant mass was fit with a double Gaussian as described in Sec. 5.

Figure 5

Combined background of $\mathrm{two}\mathrm{\text{−}}\mathrm{jet}+\gamma$ events and three-jet events in which one jet is identified as a photon. The distributions are mixed in the ratio 60% to 40%. The exponential fit is presented with a solid line.

Figure 6

Posterior density (likelihood function multiplied by Gaussian priors for $\mathcal{L}$ and ${ϵ}_{W/Z\gamma }$) integrated over $\mathcal{L}$ and ${ϵ}_{W/Z\gamma }$, versus $\sigma$.