Table 12.

Summary of model-independent upper limits for the five signal regions, in the below-Z region ($20<m_{\ell \ell }<70$ $\mathrm{GeV}$ for SR-loose, $20<m_{\ell \ell }<80$ $\mathrm{GeV}$ for all other signal regions), in the combined $ee+\mathit{\mu }\mathit{\mu }$ and individual ee and $\mathit{\mu }\mathit{\mu }$ channels. Left to right: the observed yield ($N_{\mathrm{data}}$), total expected background ($N_{\mathrm{bkg}}$), 95 % CL upper limits on the visible cross section (${⟨\mathit{ϵ}\mathit{\sigma }⟩}_{\mathrm{obs}}^{95}$) and on the number of signal events ($S_{\mathrm{obs}}^{95}$ ). The fifth column ($S_{\exp }^{95}$) shows the 95 % CL upper limit on the number of signal events, given the expected number (and $\pm 1\mathit{\sigma }$ excursions on the expectation) of background events. The last two columns indicate the $C{L}_B$ value, i.e. the confidence level observed for the background-only hypothesis, and the discovery p-value ($p(s=0)$). For an observed number of events lower than expected, the discovery p-value has been truncated at 0.5

Signal region	Channel	$N_{\mathrm{data}}$	$N_{\mathrm{bkg}}$	${⟨\mathit{ϵ}\mathit{\sigma }⟩}_{\mathrm{obs}}^{95}$ (fb)	$S_{\mathrm{obs}}^{95}$	$S_{\exp }^{95}$	$C{L}_B$	$p(s=0)$
SR-2j-bveto	$ee+\mathit{\mu }\mathit{\mu }$	54	$50\pm 8\pm 5$	1.38	28.0	${24}_{-5}^{+8}$	0.66	0.35
	ee	30	$26\pm 4\pm 3$	0.99	20.1	${18}_{-5}^{+3}$	0.73	0.28
	$\mathit{\mu }\mathit{\mu }$	24	$24\pm 3\pm 3$	0.88	17.8	${18}_{-6}^{+3}$	0.50	0.50
SR-2j-btag	$ee+\mathit{\mu }\mathit{\mu }$	79	$104\pm 11\pm 7$	0.98	19.8	${30}_{-9}^{+10}$	0.06	0.50
	ee	40	$49\pm 6\pm 4$	0.85	17.2	${20}_{-3}^{+8}$	0.19	0.50
	$\mathit{\mu }\mathit{\mu }$	39	$56\pm 6\pm 5$	0.63	12.8	${20}_{-3}^{+9}$	0.06	0.50
SR-4j-bveto	$ee+\mathit{\mu }\mathit{\mu }$	6	$8.2\pm 3.1\pm 1.4$	0.38	7.7	${8.3}_{-1.6}^{+3.2}$	0.37	0.50
	ee	1	$4.7\pm 1.6\pm 1.1$	0.19	3.9	${5.4}_{-1.4}^{+2.0}$	0.08	0.50
	$\mathit{\mu }\mathit{\mu }$	5	$3.6\pm 1.5\pm 1.0$	0.41	8.4	${6.5}_{-1.1}^{+2.9}$	0.75	0.26
SR-4j-btag	$ee+\mathit{\mu }\mathit{\mu }$	31	$38\pm 6\pm 3$	0.85	17.3	${19}_{-4}^{+7}$	0.25	0.50
	ee	14	$18\pm 3\pm 2$	0.51	10.3	${13}_{-2}^{+6}$	0.30	0.50
	$\mathit{\mu }\mathit{\mu }$	17	$20\pm 4\pm 2$	0.54	10.9	${15}_{-5}^{+4}$	0.33	0.50
SR-loose	$ee+\mathit{\mu }\mathit{\mu }$	1133	$1190\pm 40\pm 70$	6.82	138.4	${170}_{-40}^{+50}$	0.28	0.50
	ee	509	$510\pm 20\pm 40$	4.88	99.0	${100}_{-30}^{+40}$	0.51	0.48
	$\mathit{\mu }\mathit{\mu }$	624	$680\pm 20\pm 50$	4.10	83.3	${110}_{-30}^{+40}$	0.18	0.50