Annotation of ttbar/p20_taujets_note/Summary.tex, revision 1.1.1.1
1.1 uid12904 1: \section{\label{sub:xsect}Cross section}
2:
3: Having presented the preselection yelds on Section \ref{sub:Preselection} we now show the results of the
4: efficiencies for $\tau$ ID, b-tagging and trigger for all $t\bar{t}$ channels
5:
6:
7: \begin{table}[h]
8: %\begin{center}
9: \begin{tabular}{ccccc}
10: \hline
11: Selection & Relative(\%) & Cumulative(\%) \\ \hline
12: $\tau$ ID & $ 22.20 \pm 0.24 $ & $ 22.20 \pm 0.24 $ \\
13: Trigger & $ 84.54 \pm 0.55 \ $ & $ 18.77 \pm 0.22\ $ \\
14: b-tagging & $ 61.82 \pm 0.55 \ $ & $ 11.61 \pm 0.16\ $ \\ \hline
15:
16: \end{tabular}
17: \caption{$t\overline{t}\rightarrow\tau+jets$ final cut flow for taus types 1 and 2}
18: %\end{center}
19: \label{taujets_final12}
20: \end{table}
21:
22:
23: \begin{table}[h]
24: %\begin{center}
25: \begin{tabular}{ccccc}
26: \hline
27: Selection & Relative(\%) & Cumulative(\%) \\ \hline
28: $\tau$ ID & $ 12.37 \pm 0.21 $ & $ 12.37 \pm 0.21 $ \\
29: Trigger & $ 84.79 \pm 0.75 \ $ & $ 10.49 \pm 0.19\ $ \\
30: b-tagging & $ 59.63 \pm 0.75 \ $ & $ 6.26 \pm 0.13\ $ \\ \hline
31:
32: \end{tabular}
33: \caption{$t\overline{t}\rightarrow\tau+jets$ final cut flow for taus type 3}
34: %\end{center}
35: \label{taujets_final3}
36: \end{table}
37:
38:
39: \begin{table}[h]
40: %\begin{center}
41: \begin{tabular}{ccccc}
42: \hline
43: Selection & Relative(\%) & Cumulative(\%) \\ \hline
44: $\tau$ ID & $ 10.81 \pm 0.20 $ & $ 10.81 \pm 0.20 $ \\
45: Trigger & $ 83.40 \pm 0.81 \ $ & $ 9.02 \pm 0.18\ $ \\
46: b-tagging & $ 61.30 \pm 0.82 \ $ & $ 5.52 \pm 0.12\ $ \\ \hline
47:
48: \end{tabular}
49: \caption{$t\overline{t}\rightarrow e+jets$ final cut flow for taus types 1 and 2}
50: %\end{center}
51: \label{elecjets_final12}
52: \end{table}
53:
54: \begin{table}[b]
55: %\begin{center}
56: \begin{tabular}{ccccc}
57: \hline
58: Selection & Relative(\%) & Cumulative(\%) \\ \hline
59: $\tau$ ID & $ 2.25 \pm 0.11 $ & $ 2.25 \pm 0.11 $ \\
60: Trigger & $ 83.62 \pm 1.77 \ $ & $ 1.88 \pm 0.09 \ $ \\
61: b-tagging & $ 58.26 \pm 1.76 \ $ & $ 1.10 \pm 0.06\ $ \\ \hline
62:
63: \end{tabular}
64: \caption{$t\overline{t}\rightarrow e+jets$ final cut flow for taus type 3}
65: %\end{center}
66: \label{elecjets_final3}
67: \end{table}
68:
69: %\newpage
70:
71:
72: \begin{table}[b]
73: %\begin{center}
74: \begin{tabular}{ccccc}
75: \hline
76: Selection & Relative(\%) & Cumulative(\%) \\ \hline
77: $\tau$ ID & $ 3.38 \pm 0.19 $ & $ 3.38 \pm 0.19 $ \\
78: Trigger & $ 84.44 \pm 2.13 \ $ & $ 2.86 \pm 0.17\ $ \\
79: b-tagging & $ 61.25 \pm 2.16 \ $ & $ 1.75 \pm 0.11\ $ \\ \hline
80:
81: \end{tabular}
82: \caption{$t\overline{t}\rightarrow \mu +jets$ final cut flow for taus types 1 and 2.}
83: %\end{center}
84: \label{muonjets_final12}
85: \end{table}
86:
87:
88: \begin{table}[b]
89: %\begin{center}
90: \begin{tabular}{ccccc}
91: \hline
92: Selection & Relative(\%) & Cumulative(\%) \\ \hline
93: $\tau$ ID & $ 3.88 \pm 0.21 $ & $ 3.88 \pm 0.21 $ \\
94: Trigger & $ 82.79 \pm 2.04 \ $ & $ 3.21 \pm 0.18\ $ \\
95: b-tagging & $ 58.11 \pm 2.05 \ $ & $ 1.87 \pm 0.11\ $ \\ \hline
96:
97: \end{tabular}
98: \caption{$t\overline{t}\rightarrow \mu +jets$ final cut flow for taus type 3}
99: %\end{center}
100: \label{muonjets_final3}
101: \end{table}
102:
103:
104: \begin{table}[b]
105: %\begin{center}
106: \begin{tabular}{ccccc}
107: \hline
108: Selection & Relative(\%) & Cumulative(\%) \\ \hline
109: $\tau$ ID & $ 21.18 \pm 0.37 $ & $ 21.18 \pm 0.37 $ \\
110: Trigger & $ 79.56 \pm 0.90 \ $ & $ 16.85 \pm 0.34 \ $ \\
111: b-tagging & $ 62.83 \pm 0.92 \ $ & $ 10.59 \pm 0.25\ $ \\ \hline
112:
113: \end{tabular}
114: \caption{$t\overline{t}\rightarrow dilepton$ final cut flow for taus types 1 and 2}
115: %\end{center}
116: \label{dilep_final12}
117: \end{table}
118:
119:
120: \clearpage
121:
122: \begin{table}[t]
123: %\begin{center}
124: \begin{tabular}{ccccc}
125: \hline
126: Selection & Relative(\%) & Cumulative(\%) \\ \hline
127: $\tau$ ID & $ 14.73 \pm 0.34 $ & $ 14.73 \pm 0.34 $ \\
128: Trigger & $ 78.78 \pm 1.08 \ $ & $ 11.60 \pm 0.30\ $ \\
129: b-tagging & $ 63.62 \pm 1.11 \ $ & $ 7.38 \pm 0.22\ $ \\ \hline
130:
131: \end{tabular}
132: \caption{$t\overline{t}\rightarrow dilepton$ final cut flow for taus type 3.}
133: %\end{center}
134: \label{dilep_final3}
135: \end{table}
136:
137: %\newpage
138:
139:
140:
141: After having computed all efficiencies it is worthy to summarize all of them (in \%) for the different tau types:
142:
143: \begin{table}[h]
144: %\begin{center}
145: \begin{tabular}{ccccc}
146: \hline
147: Channel &Preselection & $\tau$ ID & Trigger & b-tag \\ \hline
148: $t\overline{t}\rightarrow\tau+jets$ & $ 3.70 \pm 0.02 $ & $ 22.20 \pm 0.24 $ & $ 18.77 \pm 0.22 $ & $ 11.61 \pm 0.16 $\\
149: $t\overline{t}\rightarrow e+jets$ & $ 3.54 \pm 0.02 $ & $ 10.80 \pm 0.20 $ & $ 9.02 \pm 0.18 $ & $ 5.53 \pm 0.12 $\\
150: $t\overline{t}\rightarrow \mu +jets$ & $ 1.67 \pm 0.01 $ & $ 3.38 \pm 0.19 $ & $ 2.86 \pm 0.17 $ & $ 1.75 \pm 0.11 $\\
151: $t\overline{t}\rightarrow dilepton$ & $ 1.36 \pm 0.01 $ & $ 21.18 \pm 0.37 $ & $ 16.85 \pm 0.34 $ & $ 10.59 \pm 0.25 $\\ \hline
152: \end{tabular}
153: \caption{Summary of all selections for taus type 1 \& 2.}
154: %\end{center}
155: \label{summary12}
156: \end{table}
157:
158:
159: \begin{table}[h]
160: %\begin{center}
161: \begin{tabular}{ccccc}
162: \hline
163: Channel &Preselection & $\tau$ ID & Trigger & b-tag \\ \hline
164: $t\overline{t}\rightarrow\tau+jets$ & $ 3.70 \pm 0.02 $ & $ 12.37 \pm 0.21 $ & $ 10.49 \pm 0.19 $ & $ 6.26 \pm 0.13 $\\
165: $t\overline{t}\rightarrow e+jets$ & $ 3.54 \pm 0.02 $ & $ 2.25 \pm 0.11 $ & $ 1.88 \pm 0.09 $ & $ 1.10 \pm 0.06 $\\
166: $t\overline{t}\rightarrow \mu +jets$ & $ 1.67 \pm 0.01 $ & $ 3.88 \pm 0.21 $ & $ 3.21 \pm 0.18 $ & $ 1.87 \pm 0.11 $\\
167: $t\overline{t}\rightarrow dilepton$ & $ 1.36 \pm 0.01 $ & $ 14.73 \pm 0.34 $ & $ 11.60 \pm 0.30 $ & $ 7.38 \pm 0.22 $\\ \hline
168: \end{tabular}
169: \caption{Summary of all selections for taus type 3.}
170: %\end{center}
171: \label{summary3}
172: \end{table}
173:
174: %\clearpage
175:
176: Table below summarizes the number of events in each channel after final selection.
177:
178:
179: \begin{table}[h]
180: \caption{Final number of events in the two analysis channels.}
181: %\begin{ruledtabular}
182: \begin{tabular}{cccccc}
183: \hline
184: &$\tau$ type I,II
185: &$\tau$ type I,II (fitted)
186: &$\tau$ type III
187: &$\tau$ type III (fitted)&\\
188: \hline
189: data&
190: 386 &
191: &
192: 459 &
193: &\\
194: $t\overline{t}\rightarrow\tau+jets$&
195: 72.04 $\pm$ 0.53&
196: &
197: 38.82 $\pm$ 0.39&\\
198: $t\overline{t}\rightarrow e+jets$&
199: 38.35 $\pm$ 0.36&
200: &
201: 6.52 $\pm$ 0.16&
202: &\\
203: $t\overline{t}\rightarrow\mu+jets$&
204: 4.81 $\pm$ 0.14&
205: &
206: 5.14 $\pm$ 0.14&
207: &\\
208: $t\overline{t}\rightarrow l+l$&
209: 6.02 $\pm$ 0.07&
210: &
211: 4.20 $\pm$ 0.06&
212: &\\
213: $t\overline{t}$ total MC&
214: &
215: 121.22 $\pm$ 0.43&
216: &
217: 54.68 $\pm$ 0.20&\\
218: $t\overline{t}$ total fitted&
219: &
220: 133.04 $\pm$ 17.09&
221: &
222: 33.12 $\pm$ 15.04&\\
223: $W$+jets&
224: 17.82 $\pm$ 0.33&
225: &
226: 11.26 $\pm$ 0.23&
227: &\\
228: $Z$+jets&
229: 2.78 $\pm$ 0.14&
230: &
231: 2.39 $\pm$ 0.12&
232: &\\
233: QCD&
234: &
235: 232.35 $\pm$ 17.09&
236: &
237: 412.22 $\pm$ 15.04\\
238: Signal significance&
239: &
240: 6.77&
241: &
242: 1.54
243: &\\
244: S/B ratio&
245: &
246: 0.52&
247: &
248: 0.08\\
249: \end{tabular}
250: %\end{ruledtabular}
251: \label{event yeild summary}
252: \end{table}
253: %
254:
255: \clearpage
256:
257: %The cross section is defined as
258: %$\sigma=\frac{Number\, of\, signal\, events}{\varepsilon(t\bar{t})\cdot BR(t\bar{t}\rightarrow \tau+jets)\cdot Luminosity}$.
259: %However, we are not simply doing a `counting experiment`, but want to utilize the entire range of NN output.
260: The cross section was measured by minimizing the sum of
261: the negative log-likelihood functions for each bin of both the types 1 and 2 channel and the type 3 $\tau$ channel.
262: These are functions used by MINUIT to perform fits shown in Figs \ref{fig:nnout_type2} and \ref{fig:nnout_type3}
263: in Section \ref{sub:NN-variables}. But there $L$ was function of $f(QCD)$ and now we want to use it to measure the cross
264: section, so we must express it in terms of $\sigma(\ttbar)$:
265: \begin{center}
266: \begin{equation}
267: L(\sigma, \tilde{N}_{i}, N^{obs}_{i}) \equiv -log(\prod_{i} \frac{\tilde{N}^{N^{obs}_{i}}_{i}}{N^{obs}_{i}!} e^{-\tilde{N}_{i}})
268: \end{equation}
269: \end{center}
270:
271: \noindent where \(\tilde{N}_{i} = \sigma \times BR \times \mathcal{L} \times \epsilon(t\bar{t})_{i} + N_{bkg}\) is number
272: events predicted in bin i of the data NN distribution and \(N^{obs}_{i}\) is the actual count observed in that bin.
273: The cross-section is then the minimum value of each function. But, as stressed out in Section \ref{sub:Results-of-the},
274: we have to take
275: into account both signal ($\ttbar$) and electroweak contamination in the loose-tight sample we
276: use to model QCD in the high NN region used for
277: the measurement. The electroweak component is small and therefore it is kept fixed during the fit and
278: subtracted from the loose-tight sample.
279: However, as dicussed before, the numbers for signal contamination are 5.4\% and 3.0\% for taus types
280: 1 and 2 and type 3 respectively
281: when we assumed a $t\bar{t}$ cross section of 7.46 pb. This means that 5.4\% (12.55 events) of 232.35 QCD
282: events for taus types 1 and 2 are actually $\ttbar$ events and 3.0\% (12.37 events) of 412.22 QCD events
283: for taus type 3 are actually $\ttbar$
284: events. 12.55 and 12.37 events represent increases of 9.43\% and 37.35\% on the number of signal events for types 1 and 2
285: and type 3 respectively. However this is not the final measurement yet since the cross-section
286: measurement only makes sense if the cross-section we measure in the and is the same as the one we have assumed
287: to normalize $t\bar{t}$ MC samples. This means that we had to iterate back
288: by normalizing the signal samples until we found a convergence of the cross-section. Table XXIII summarizes
289: the iteration process.
290:
291: \begin{table}[htbp]
292: \label{est}
293: \begin{center}
294: \begin{tabular}{|c|r|r|r|} \hline
295: Assumed $\sigma(\ttbar)$ (pb) & signal contamination for types 1 \& 2 (\%) & signal contamination for type
296: 3 (\%) & measured $\sigma(\ttbar)$ (pb) \\ \hline
297:
298: \hline
299:
300: \multicolumn{1}{|c|}{7.46} & \multicolumn{1}{c|}{5.4} & \multicolumn{1}{c|}{3.0} & \multicolumn{1}{c|}{8.37} \\ \hline
301:
302: %$t\bar{t} \rightarrow \mbox{dilepton}$ & \multicolumn{1}{c|}{1.4} \\ \hline
303:
304: \multicolumn{1}{|c|}{8.37} & \multicolumn{1}{c|}{6.1} & \multicolumn{1}{c|}{3.3} & \multicolumn{1}{c|}{8.42} \\ \hline
305:
306: \multicolumn{1}{|c|}{8.42} & \multicolumn{1}{c|}{6.2} & \multicolumn{1}{c|}{3.4} & \multicolumn{1}{c|}{8.46} \\ \hline
307:
308:
309: \multicolumn{1}{|c|}{8.46} & \multicolumn{1}{c|}{6.2} & \multicolumn{1}{c|}{3.4} & \multicolumn{1}{c|}{8.46} \\ \hline
310:
311: \end{tabular}
312: \caption{Cross-section iteration process.}
313: \end{center}
314: \label{iteration1}
315: \end{table}
316:
317: Table above shows that when we assumed a cross-section of 8.46 pb we measured the exact same value, which means that we had to take
318: into account signal contaminations of 6.2\% (14.40 events) and 3.4\% (14.02 events) for taus types 1 and 2 and 3 respectively.
319: This represents an increase in the number of signal events of 10.82\% for types 1 and 2 and 42.33\% for type 3.
320: By considering such events as part of the signal $\ttbar$ sample we measure for the cross-sections:
321:
322: %\newpage
323:
324:
325: \begin{center}$\tau$+jets types 1 and 2 cross section: \[\sigma (t\overline{t}) =
326: 8.83\;\;_{-1.12}^{+1.14}\;\;({\textrm{stat}})\;\;_{-0.94}^{+0.89}\;\;({\textrm{syst}})\;\;\pm 0.3\;\;({\textrm{lumi}})\;\; \rm{pb,}\]
327: \par\end{center}
328:
329: \begin{center}$\tau$+jets type 3 cross section: \[\sigma (t\overline{t}) =
330: 6.06\;\;_{-2.62}^{+2.77}\;\;({\textrm{stat}})\;\;_{-0.99}^{+0.94}\;\;({\textrm{syst}})\;\;\pm 0.3\;\;({\textrm{lumi}})\;\; \rm{pb,}\]
331: \par\end{center}
332:
333:
334:
335: \begin{center}Combined cross section: \[\sigma (t\overline{t}) =
336: 8.46\;\;_{-1.04}^{+1.06}\;\;({\textrm{stat}})\;\;_{-0.88}^{+0.92}\;\;({\textrm{syst}})\;\;\pm 0.3\;\;({\textrm{lumi}})\;\; \rm{pb.}\]
337: \par\end{center}
338:
339: \noindent The correspondent likelihoods of these measurements are shown in Figures \ref{fig:type2_llhood}, \ref{fig:type3_llhood}
340: and \ref{fig:type123_llhood}. Figures \ref{fig:xsec_pres2_llhood}, \ref{fig:xsec_pres3_llhood}
341: and \ref{fig:xsec_pres123_llhood} show zoomed in graphs of the same likelihood functions described above.
342:
343:
344: All associated systematics concerning this measurement can be seen in Table \ref{cap:Syst1}.
345:
346: %\newpage
347:
348: \begin{figure}[h]
349: \includegraphics[scale=0.38]{plots2/type2_llhood.eps}
350: \caption{The log likelihood function for type 1 and 2 $\tau$ channel}
351: \label{fig:type2_llhood}
352: \end{figure}
353:
354: %\newpage
355:
356: \begin{figure}[h]
357: \includegraphics[scale=0.38]{plots2/type3_llhood.eps}
358: \caption{The log likelihood function for type 3 $\tau$ channel}
359: \label{fig:type3_llhood}
360: \end{figure}
361:
362:
363: \begin{figure}[b]
364: \includegraphics[scale=0.38]{plots2/type123_llhood.eps}
365: \caption{The log likelihood function for all three types combined}
366: \label{fig:type123_llhood}
367: \end{figure}
368:
369: \clearpage
370:
371: \begin{figure}[h]
372: \includegraphics[scale=0.38]{plots2/xsec12_pres.eps}
373: \caption{Zoom in of the log likelihood function for type 1 and 2 $\tau$ channel}
374: \label{fig:xsec_pres2_llhood}
375: \end{figure}
376:
377: %\newpage
378:
379: \begin{figure}[h]
380: \includegraphics[scale=0.38]{plots2/xsec3_pres.eps}
381: \caption{Zoom in of the log likelihood function for type 3 $\tau$ channel}
382: \label{fig:xsec_pres3_llhood}
383: \end{figure}
384:
385:
386: \begin{figure}[b]
387: \includegraphics[scale=0.38]{plots2/xsecall_pres.eps}
388: \caption{Zoom in of the log likelihood function for all three types combined}
389: \label{fig:xsec_pres123_llhood}
390: \end{figure}
391:
392: \clearpage
393:
394:
395: After measuring the combined cross section we observed a significant higher statistical uncertainty value if
396: compared to the one we expected to see based on the fact that we have approximately 5 times more
397: data than in p17, where the signal contamination was not taken into account (see Appendix \ref{app:xsec_nocont}).
398: Further investigation showed that the cut NNelec $>$ 0.9 applied to taus type 2 only was responsible for such
399: discrepancy. Below we show the same measurement as done above but now with no NNelec cut applied.
400:
401:
402: Table below summarizes the number of events in each channel after final selection.
403:
404:
405: \begin{table}[h]
406: \caption{Final number of events in the two analysis channels.}
407: %\begin{ruledtabular}
408: \begin{tabular}{cccccc}
409: \hline
410: &$\tau$ type I,II
411: &$\tau$ type I,II (fitted)
412: &$\tau$ type III
413: &$\tau$ type III (fitted)&\\
414: \hline
415: data&
416: 583 &
417: &
418: 459 &
419: &\\
420: $t\overline{t}\rightarrow\tau+jets$&
421: 85.46 $\pm$ 0.58&
422: &
423: 38.82 $\pm$ 0.39&\\
424: $t\overline{t}\rightarrow e+jets$&
425: 175.23 $\pm$ 0.85&
426: &
427: 6.52 $\pm$ 0.16&
428: &\\
429: $t\overline{t}\rightarrow\mu+jets$&
430: 8.98 $\pm$ 0.19&
431: &
432: 5.14 $\pm$ 0.14&
433: &\\
434: $t\overline{t}\rightarrow l+l$&
435: 12.62 $\pm$ 0.10&
436: &
437: 4.18 $\pm$ 0.06&
438: &\\
439: $t\overline{t}$ total MC&
440: &
441: 282.27 $\pm$ 1.05&
442: &
443: 54.67 $\pm$ 0.41&\\
444: $t\overline{t}$ total fitted&
445: &
446: 260.71 $\pm$ 20.74&
447: &
448: 35.73 $\pm$ 15.28&\\
449: $W$+jets&
450: 39.65 $\pm$ 0.50&
451: &
452: 11.26 $\pm$ 0.25&
453: &\\
454: $Z$+jets&
455: 4.56 $\pm$ 0.10&
456: &
457: 2.38 $\pm$ 0.11&
458: &\\
459: QCD&
460: &
461: 278.04 $\pm$ 20.74&
462: &
463: 409.62 $\pm$ 15.28\\
464: Signal significance&
465: &
466: 10.80&
467: &
468: 1.67
469: &\\
470: S/B ratio&
471: &
472: 0.80&
473: &
474: 0.08\\
475: \end{tabular}
476: %\end{ruledtabular}
477: \label{event yeild summary}
478: \end{table}
479: %
480:
481: Table below shows the iteration process in this case and and the cross section measurement follows:
482:
483: \begin{table}[htbp]
484: \label{est}
485: \begin{center}
486: \begin{tabular}{|c|r|r|r|} \hline
487: Assumed $\sigma(\ttbar)$ (pb) & signal contamination for types 1 \& 2 (\%) & signal contamination for type
488: 3 (\%) & measured $\sigma(\ttbar)$ (pb) \\ \hline
489:
490: \hline
491:
492: \multicolumn{1}{|c|}{7.46} & \multicolumn{1}{c|}{6.0} & \multicolumn{1}{c|}{3.0} & \multicolumn{1}{c|}{6.84} \\ \hline
493:
494: %$t\bar{t} \rightarrow \mbox{dilepton}$ & \multicolumn{1}{c|}{1.4} \\ \hline
495:
496: \multicolumn{1}{|c|}{6.84} & \multicolumn{1}{c|}{5.4} & \multicolumn{1}{c|}{2.7} & \multicolumn{1}{c|}{6.91} \\ \hline
497:
498: \multicolumn{1}{|c|}{6.91} & \multicolumn{1}{c|}{5.5} & \multicolumn{1}{c|}{2.8} & \multicolumn{1}{c|}{6.92} \\ \hline
499:
500:
501: \multicolumn{1}{|c|}{6.92} & \multicolumn{1}{c|}{5.5} & \multicolumn{1}{c|}{2.8} & \multicolumn{1}{c|}{6.92} \\ \hline
502:
503: \end{tabular}
504: \caption{Cross-section iteration process.}
505: \end{center}
506: \label{iteration}
507: \end{table}
508:
509:
510: %\newpage
511:
512:
513: \begin{center}$\tau$+jets types 1 and 2 cross section: \[\sigma (t\overline{t}) =
514: 7.03\;\;_{-0.56}^{+0.54}\;\;({\textrm{stat}})\;\;_{-0.61}^{+0.65}\;\;({\textrm{syst}})\;\;\pm 0.3\;\;({\textrm{lumi}})\;\; \rm{pb,}\]
515: \par\end{center}
516:
517: \begin{center}$\tau$+jets type 3 cross section: \[\sigma (t\overline{t}) =
518: 4.36\;\;_{-2.50}^{+2.62}\;\;({\textrm{stat}})\;\;_{-0.61}^{+0.62}\;\;({\textrm{syst}})\;\;\pm 0.3\;\;({\textrm{lumi}})\;\; \rm{pb,}\]
519: \par\end{center}
520:
521:
522:
523: \begin{center}Combined cross section: \[\sigma (t\overline{t}) =
524: 6.92\;\;_{-0.54}^{+0.54}\;\;({\textrm{stat}})\;\;_{-0.60}^{+0.62}\;\;({\textrm{syst}})\;\;\pm 0.3\;\;({\textrm{lumi}})\;\; \rm{pb,}\]
525: \par\end{center}
526:
527:
528: As we can see the statistical uncertainty decreases to 0.54 pb which is in a good agreement to what we would expect if compared
529: to 1.2 pb measured in p17. Appendix \ref{app:xsec_nocont} shows cross sections measurements when signal contamination is not
530: taken into account for both NNelec $>$ 0.9 and no NNelec cut applied. Once again we observed a discrepancy when NNelec is applied
531: and the expected value when NNelec is not applied.
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