Search for New Particles Decaying to Dijets, Bottom Quarks, and Top Quarks at CDF

TL;DR

This paper reports on three searches for new particles decaying into dijets, bottom quarks, and top quarks at CDF, setting mass limits and observing fluctuations that could hint at new physics beyond the standard model.

Contribution

First search for hadronic decays of axigluons, excited quarks, technirhos, W', Z', and diquarks at CDF with new mass limits; second for b-anti-b resonances; third for top-antitop resonances, providing the most stringent limits to date.

Findings

No significant evidence for new particles was found.

Upward fluctuations observed are not statistically significant.

Mass limits approaching 600 GeV for certain new particles.

Abstract

We present three searches for new particles at CDF. First, using 70 pb^-1 of data we search the dijet mass spectrum for resonances. There is an upward fluctuation near 550 GeV (2.6 sigma) with an angular distribution that is adequately described by either QCD alone or QCD plus 5% signal. There is insufficient evidence to claim a signal, but we set the most stringent mass limits on the hadronic decays of axigluons, excited quarks, technirhos, W', Z', and E6 diquarks. Second, using 19 pb^-1 of data we search the b-tagged dijet mass spectrum for b anti-b resonances. Again, an upward fluctuation near 600 GeV (2 sigma) is not significant enough to claim a signal, so we set the first mass limits on topcolor bosons. Finally, using 67 pb^-1 of data we search the top quark sample for t anti-t resonances like a topcolor Z'. Other than an insignificant shoulder of 6 events on a background of 2.4 in the mass region 475-550 GeV, there is no evidence for new particle production. Mass limits, currently in progress, should be sensitive to a topcolor Z' near 600 GeV. In all three searches there is insufficient evidence to claim new particle production, yet there is an exciting possibility that the upward fluctuations are the first signs of new physics beyond the standard model.