Search for Large Extra Dimensions in the $\mathrm{\text{Monojet}}+{\mathrm{E̸}}_T$ Channel with the DØ Detector

We present a search for large extra dimensions (ED) in $p\overline{p}$ collisions at a center-of-mass energy of 1.8 TeV using data collected by the DØ detector at the Fermilab Tevatron in 1994–1996. Data corresponding to $78.8\pm 3.9{\mathrm{p}\mathrm{b}}^{-1}$ are examined for events with large missing transverse energy, one high-$p_T$ jet, and no isolated muons. There is no excess observed beyond expectation from the standard model, and we place lower limits on the fundamental Planck scale of 1.0 and 0.6 TeV for 2 and 7 ED, respectively.

Figure 1

(a) Comparison of data (points with error bars) with expected background (dashed histogram), and the sum of background and signal for $n=2$, $M_D=800\mathrm{G}\mathrm{e}\mathrm{V}$ (dotted histogram), as a function of ${\mathrm{E̸}}_T$, for $E_T(j_1)>150\mathrm{G}\mathrm{e}\mathrm{V}$, ${\mathrm{E̸}}_T>150\mathrm{G}\mathrm{e}\mathrm{V}$, and $E_T(j_2)<50\mathrm{G}\mathrm{e}\mathrm{V}$; and (b) comparison of ${\mathrm{E̸}}_T$ for data with $E_T(j_1)>115\mathrm{G}\mathrm{e}\mathrm{V}$, ${\mathrm{E̸}}_T>115\mathrm{G}\mathrm{e}\mathrm{V}$, and $E_T(j_2)<40\mathrm{G}\mathrm{e}\mathrm{V}$ with expected background.

Figure 2

The $95\%$ C.L. exclusion contours on the fundamental Planck scale ($M_D$) and number of extra dimensions ($n$) for monojet production at DØ (solid lines). The dashed curves correspond to limits from LEP, and the dotted curve is the limit from CDF, both for $\gamma +G_{\mathrm{K}\mathrm{K}}$ production.