Search for High Mass Resonances Decaying to Muon Pairs in $\sqrt{s}=1.96\mathrm{TeV}$ $p\overline{p}$ Collisions

We present a search for a new narrow, spin-1, high mass resonance decaying to ${\mu }^{+}{\mu }^{-}+X$, using a matrix-element-based likelihood and a simultaneous measurement of the resonance mass and production rate. In data with $4.6{\mathrm{fb}}^{-1}$ of integrated luminosity collected by the CDF detector in $p\overline{p}$ collisions at $\sqrt{s}=1960\mathrm{GeV}$, the most likely signal cross section is consistent with zero at 16% confidence level. We therefore do not observe evidence for a high mass resonance and place limits on models predicting spin-1 resonances, including $M>1071\mathrm{GeV}/c^2$ at 95% confidence level for a $Z^{\prime }$ boson with the same couplings to fermions as the $Z$ boson.

Figure 1

Top: The distributions of $M_{\mu \mu }$ for data with $4.6{\mathrm{fb}}^{-1}$ of integrated luminosity (triangles) and expected SM backgrounds (histograms) with two example $Z_{\mathrm{SM}}^{\prime }$ signals. Bottom: The relative difference between observed and expected data, as a function of dimuon mass. Error bars show statistical uncertainty.

Figure 2

Observed 95% C.L. limits in 1D raster scan (top) and 2D intervals (bottom) for the data with $4.6{\mathrm{fb}}^{-1}$ of integrated luminosity. The solid circle indicates the best-fit value $(\widehat{M},\widehat{s})$; in regions below each line, 25%, 50%, 68%, 95%, and 99% of pseudoexperiments drawn from the point $(M,s)$ yield a likelihood ratio $L(M,s)/L(\widehat{M},\widehat{s})$ greater than or equal to the observed ratio in the data. A 16% region (not shown) is the smallest region that still includes the standard model.

Figure 3

Observed 95% C.L. limits for the data with $4.6{\mathrm{fb}}^{-1}$ of integrated luminosity expressed as limits on the up- and down-type charges $c_u$ and $c_d$ [4]. The solid and dotted lines show possible models in the $U(1{)}_{B-XL}$ and $U(1{)}_{10+x\overline{5}}$ groups, respectively. The dashed lines show the range for models in the $U(1{)}_{q+xu}$ group.