Search for Excited and Exotic Electrons in the $e\gamma$ Decay Channel in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We present a search for excited and exotic electrons ($e^{*}$) decaying to an electron and a photon, both with high transverse momentum. We use $202{\mathrm{pb}}^{-1}$ of data collected in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ with the Collider Detector at Fermilab II detector. No signal above standard model expectation is seen for associated $e{e}^{*}$ production. We discuss the $e^{*}$ sensitivity in the parameter space of the excited electron mass $M_{e^{*}}$ and the compositeness energy scale $\Lambda$. In the contact interaction model, we exclude $132\mathrm{GeV}/c^2<M_{e^{*}}<879\mathrm{GeV}/c^2$ for $\Lambda =M_{e^{*}}$ at 95% confidence level (C.L.). In the gauge-mediated model, we exclude $126\mathrm{GeV}/c^2<M_{e^{*}}<430\mathrm{GeV}/c^2$ at 95% C.L. for the phenomenological coupling $f/\Lambda \approx {10}^{-2}{\mathrm{GeV}}^{-1}$.

Figure 1

The cumulative $e\gamma$ mass distribution for all backgrounds. Integrating over all masses, the total expected number of $e\gamma$ entries is $6.5\pm 0.1(\mathrm{stat}{)}_{-0.7}^{+0.9}(\mathrm{syst})$.

Figure 2

The experimental $\mathrm{\text{cross section}}\times \mathrm{\text{branching ratio}}$ limits for the CI and GM models from this analysis, compared to the CI model prediction for $\Lambda =M_{e^{*}}$ and the GM model prediction for $\Lambda /f=M_{e^{*}}$. The mass limits are indicated.

Figure 3

The 2D parameter space regions excluded by this analysis for (a) the GM model, along with the current world limits, and (b) the CI model.