We present a search for excited or exotic electrons decaying to
  an electron and a photon with high transverse momentum. 
  An oppositely charged electron is produced in association
 with the excited electron,  yielding a final state dielectron + photon
 signature.  The discovery of excited electrons would be a
 first indication of lepton compositeness.

  We use $\sim$202 pb$^{-1}$ of data collected in
 {\mbox{$p\bar p$}}\ collisions at {\mbox{$\sqrt{s}$ =\ 1.96\ TeV }}
 with the Collider Detector at Fermilab during March 2001 
 through September 2003.  The data are consistent with standard 
 model expectations.  Upper limits are set  on the 
 experimental cross-section $\sigma(\bar p p
 \rightarrow e e^* \rightarrow e e \gamma)$ at the 95\% 
 confidence level in a contact-interaction model and a 
 gauge-mediated interaction model. Limits are also
 presented as exclusion regions in the parameter space of 
 the excited electron mass ($M_{e^*}$) and
 the compositeness energy scale ($\Lambda$). In the 
 contact-interaction model, for which there are no 
 previously published limits, we find $M_{e^*}<906$ GeV is 
 excluded for $M_{e^*} = \Lambda$. In the gauge-mediated 
 model, the exclusion region in the $M_{e^*}$ versus 
 the phenomenological coupling $f/\Lambda$
 parameter space is extended to $M_{e^*} < 430$ GeV 
 for $f/\Lambda \sim 10^{-2}\ {\rm GeV^{-1}}$.  In comparison, other
 experiments have excluded $M_{e^*} < 280$ GeV for 
 $f/\Lambda \sim 10^{-2}\ {\rm GeV^{-1}}$.


Posted to /cdf/pub/thesis/cdf7547_Gerberich_thesis.ps
    http://www-cdf.fnal.gov/thesis/cdf7547_Gerberich_thesis.ps

Posted by hkg@fcdfwww