Search for New Particles Decaying to Dijets at CDF

Abstract

We have used 106 pb^-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at the 95% confidence level models containing the following new particles: axigluons and flavor universal colorons with mass between 200 and 980 GeV/c, excited quarks with mass between 80 and 570 GeV/c^2 and between 580 and 760 GeV/c^2, color octet technirhos with mass between 260 and 480 GeV/c^2, W' bosons with mass between 300 and 420 GeV/c^2, and E_6 diquarks with mass between 290 and 420 GeV/c^2.

Figures (4)

• Figure 1: The dijet mass distribution (circles) compared to a QCD simulation (boxes) and fit to a smooth parameterization (solid curve). Also shown are simulations of excited quark signals in the CDF detector (dashed curves). In the data and simulations we require that both jets have pseudorapidity $|\eta|<2.0$ and that the dijet system satisfies $|\cos\theta^*|<2/3$.
• Figure 2: The fractional difference between the dijet mass distribution (points) and a smooth background fit (solid line) is compared to simulations of excited quark signals in the CDF detector (dashed curves). The inset shows the systematic uncertainty for a new particle signal (see text).
• Figure 3: The upper limit on the cross section times branching ratio for new particles decaying to dijets (points) is compared to theoretical predictions for axigluons ref_axi, flavor universal colorons ref_coloron, excited quarks ref_qstar, color octet technirhos ref_trho, new gauge bosons $W^{\prime}$ and $Z^{\prime}$ref_gauge, and $E_6$ diquarks ref_diquark. The limit and theory curves require that both jets have pseudorapidity $|\eta|<2.0$ and that the dijet system satisfies $|\cos\theta^*|<2/3$.
• Figure 4: The region of the coupling vs. mass plane excluded by previous CDF measurements ref_dijet_prl_1aref_qstar_prl in the $q^*\rightarrow q\gamma$ and $q^*\rightarrow qW$ channels (clear hatched region) and $q^*\rightarrow qg$ channels (shaded hatched region on left) in run 1A is extended by this $q^*\rightarrow qg$ search in run 1A plus run 1B (shaded hatched region on right). The CDF excluded regions are compared to the regions excluded by LEP I and UA2 (shaded regions) ref_other.