Search for anomalous production of events with a photon, jet, $b$-quark jet, and missing transverse energy

We present a signature-based search for the anomalous production of events containing a photon, two jets, of which at least one is identified as originating from a $b$ quark, and missing transverse energy (${\mathrm{E̸}}_T$). The search uses data corresponding to $2.0{\mathrm{fb}}^{-1}$ of integrated luminosity from $p\overline{p}$ collisions at a center-of-mass energy of $\sqrt{s}=1.96\mathrm{TeV}$, collected with the CDF II detector at the Fermilab Tevatron. From $6.69747\times {10}^6$ events with a photon candidate with transverse energy $E_T>25\mathrm{GeV}$, we find 617 events with ${\mathrm{E̸}}_T>25\mathrm{GeV}$ and two or more jets with $E_T>15\mathrm{GeV}$, at least one identified as originating from a $b$ quark, versus an expectation of $607\pm 113$ events. Increasing the requirement on ${\mathrm{E̸}}_T$ to 50 GeV, we find 28 events versus an expectation of $30\pm 11$ events. We find no indications of non-standard-model phenomena.

Figure 1

Templates of the invariant mass of all tracks in a secondary vertex arising from bottom quarks, charm quarks, and light quarks and gluons from Monte Carlo simulations, normalized to unit area.

Figure 2

The secondary vertex mass fit in events containing standard photons, for the control sample (left panel) and the search sample (right panel). Note the uncertainties on $f_c$ and $f_b$ are correlated and purely statistical.

Figure 3

The distribution in photon $E_T$ observed (points) and from backgrounds (histogram). The KS $p$-value is 63.7%. Note that the single event in a bin that has no predicted background is due to the choice of binning and is therefore not a significant excess.

Figure 4

The distribution in the $b$-jet $E_T$ observed (points) and from backgrounds (histograms). The KS $p$-value is 59.7%.

Figure 5

The distribution in the untagged jet $E_T$ observed (points) and from backgrounds (histogram). The KS $p$-value is 10.4%. Note that the single event in a bin that has no predicted background is due to the choice of binning and is therefore not a significant excess.

Figure 6

The distribution in missing transverse energy observed (points) and from backgrounds (histogram). The KS $p$-value is 7.0%.

Figure 7

The distribution in jet multiplicity observed (points) and from backgrounds (histogram) in the logarithmic scale. The KS $p$-value is 19.0%.

Figure 8

The distribution of the scalar sum of the transverse momenta of the $\gamma$, all jets in the event, and ${\mathrm{E̸}}_T$ observed (points) and from backgrounds (histogram). The KS $p$-value is 99.7%.

Figure 9

The distribution of the mass of the $\mathrm{\text{photon}}+b$ jet observed (points) and from backgrounds (histogram). The KS $p$-value is 62.0%.

Figure 10

The distribution of the dijet mass observed (points) and from backgrounds (histogram). The KS $p$-value is 9.8%.

Figure 11

The distribution of the invariant mass of the $\gamma$, the $b$ jet, and the 2nd jet observed (points) and from backgrounds (histogram). The KS $p$-value is 99.8%.

Figure 12

The distribution of the transverse mass of the $\mathrm{\text{photon}}+{\mathrm{E̸}}_T$ observed (points) and from backgrounds (histogram). The KS $p$-value is 96.8%.

Figure 13

The distribution of the transverse mass of the $b$ jet, the 2nd jet, and missing transverse energy observed (points) and from backgrounds (histogram). The KS $p$-value is 21.1%.

Figure 14

$M(bj)$ versus $M(\gamma bj)$ for the events which satisfy the selections in Table 1, observed (big dots) and expected (small dots).