Search for Resonant Pair Production of Neutral Long-Lived Particles Decaying to $b\overline{b}$ in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We report on a first search for resonant pair production of neutral long-lived particles (NLLP) which each decay to a $b\overline{b}$ pair, using $3.6{\mathrm{fb}}^{-1}$ of data recorded with the D0 detector at the Fermilab Tevatron collider. We search for pairs of displaced vertices in the tracking detector at radii in the range 1.6–20 cm from the beam axis. No significant excess is observed above background, and upper limits are set on the production rate in a hidden-valley benchmark model for a range of Higgs boson masses and NLLP masses and lifetimes.

Figure 1

Material map in the plane transverse to the beam line, generated using SVs with three attached tracks, in events passing the initial selection. The structure of the silicon detector and supports are clearly seen.

Figure 2

The minimum mass of the two SVs, for data, background MC, and signal MC events with $M_H=120\mathrm{GeV}$, $m_{\mathrm{HV}}=15\mathrm{GeV}$, and $L_d=5\mathrm{cm}$. The hatched region shows the uncertainty on the background MC events.

Figure 3

The maximum collinearity of the two SVs, for data, background MC, and signal MC with $M_H=120\mathrm{GeV}$, $m_{\mathrm{HV}}=40\mathrm{GeV}$, and $L_d=5\mathrm{cm}$. The hatched region shows the uncertainty on the background MC.

Figure 4

The expected and observed 95% C.L. limits on $\sigma (H+X)\times \mathrm{BR}(H\to \mathrm{HV}\mathrm{HV})\times {\mathrm{BR}}^2(\mathrm{HV}\to b\overline{b})$ for each $M_H$ studied, $m_{\mathrm{HV}}=15$, 40 GeV, and various values of $v$-hadron $L_d$. The band shows $\pm 1$ standard deviation on the expected limit. The reference Higgs boson cross section from the SM [11] is shown, which assumes 100% for $\mathrm{BR}(H\to \mathrm{HV}\mathrm{HV})$ and $\mathrm{BR}(\mathrm{HV}\to b\overline{b})$.