| 1 |
|
\section{Search in the Same-sign Dilepton Final State} |
| 2 |
|
\label{sec:ss} |
| 3 |
|
|
| 4 |
+ |
\begin{figure*}[!ht] |
| 5 |
+ |
\centering |
| 6 |
+ |
%\begin{center} |
| 7 |
+ |
\begin{tabular}{cc} |
| 8 |
+ |
\subfloat[] {\includegraphics[width=0.5\textwidth]{HCPPlots/SS_B1.pdf}} & |
| 9 |
+ |
\subfloat[] {\includegraphics[width=0.4\textwidth]{HCPPlots/T2bb_interpretation.pdf}} \\ |
| 10 |
+ |
\end{tabular} |
| 11 |
+ |
\caption{ |
| 12 |
+ |
Interpretation of the results of the search in (a) the same-sign dilepton final state for |
| 13 |
+ |
bottom squark pair production with $\tilde{b}\to t\chim$ depicted in Fig.~\ref{fig:diagrams}(d), and (b) |
| 14 |
+ |
the all-hadronic final state for bottom squark pair production with $\tilde{b}\to b\lsp$ depicted in Fig.~\ref{fig:diagrams}(c). |
| 15 |
+ |
\label{fig:ss_interpretation} |
| 16 |
+ |
} |
| 17 |
+ |
%\end{center} |
| 18 |
+ |
\end{figure*} |
| 19 |
+ |
|
| 20 |
|
This section presents a search in the same-sign (SS) dilepton final state, based on 10.5 fb$^{-1}$. |
| 21 |
< |
A wide variety of new physics processes may produce events with SS leptons, which provide a very clean |
| 21 |
> |
A wide variety of new physics scenarios may produce events with SS leptons, which provide a very clean |
| 22 |
|
final state due to low SM background expectations. In particular, this final state is sensitive to |
| 23 |
< |
direct pair production of bottom squarks with $\tilde{b}\to t \chi^{\pm}\to t W \lsp$ depicted in Fig.~\ref{fig:diagrams}(d), |
| 23 |
> |
direct pair production of bottom squarks with $\tilde{b}\to t \chim \to t W \lsp$ depicted in Fig.~\ref{fig:diagrams}(d), |
| 24 |
|
as well as to gluino-mediated production of top and bottom squarks. |
| 25 |
|
|
| 26 |
|
We select events with two leptons (e or $\mu$) with \pt\ $>$ 20 GeV and dilepton invariant mass $m_{\ell\ell}>8$ GeV. |
| 34 |
|
b-tagged jets (using CSVM). The requirement that both b-jets are identified and well-separated from the selected leptons |
| 35 |
|
reduces the \ttljets\ background by an order of magnitude. |
| 36 |
|
|
| 37 |
+ |
|
| 38 |
|
There are three sources of SM background passing the above preselection. |
| 39 |
|
The first background source is referred to as ``fake leptons'' and includes leptons from heavy-flavor decay, |
| 40 |
|
misidentified hadrons, muons from meson decay in flight, or electrons from unidentified photon conversions. |
| 44 |
|
on studies of fake |
| 45 |
|
leptons in jet events. The second background, estimated from MC, consists of rare SM processes and is dominated |
| 46 |
|
by $t\bar{t}$W and $t\bar{t}$Z. The systematic uncertainty on both the fake lepton and rare backgrounds is 50\%. |
| 47 |
< |
A third, small background contributions is from ``charge flips'' and consists of events with opposite-sign leptons |
| 48 |
< |
where one of the leptons is an electron whose charge is misreconstructed. This background is based on MC predictions, |
| 49 |
< |
which are validated using a sample of Z$\to e^+e^-$ events. |
| 47 |
> |
A third, small background contribution is from ``charge flips'' and consists of events with opposite-sign (OS) leptons |
| 48 |
> |
where one of the leptons is an electron whose charge is misreconstructed. |
| 49 |
> |
This background is estimated from an OS dilepton data sample, weighted by the electron charge misreconstruction probability, |
| 50 |
> |
which is extracted from studies of Z$\to$ee events in data and MC. |
| 51 |
> |
%This background is based on MC predictions, which are validated using a sample of Z$\to e^+e^-$ events. |
| 52 |
|
|
| 53 |
|
Signal regions are defined by placing additional requirements on the jet multiplicity, b-tagged jet multiplicity, |
| 54 |
< |
\met, and $H_T$, defined as the scalar sum of the transverse momenta of selected jets. The observed data yields |
| 55 |
< |
in these signal regions are compared to the SM background expectations in |
| 56 |
< |
Table~\ref{tab:ss}. Good agreement is observed between the data and the expected background in all signal regions. |
| 57 |
< |
|
| 58 |
< |
In Fig.~\ref{fig:ss_interpretation}(a),tThe results are interpreted using the model of bottom squark pair |
| 59 |
< |
production with $\tilde{b}\to t \chi^{\pm}$ depicted in Fig.~\ref{fig:diagrams}(d). |
| 60 |
< |
The most sensitive signal region in most of the model parameter space is SR3 (see Table~\ref{tab:ss}). |
| 61 |
< |
These results probe bottom squarks with masses up to 450 GeV. |
| 62 |
< |
The constraint on the bottom squark mass from naturalness is similar to that on the top squark, requiring |
| 63 |
< |
a mass less than 500-700~GeV. Several additional interpretations for models with gluino-mediated top and |
| 54 |
> |
\met, and $H_T$, defined as the scalar sum of the transverse momenta of selected jets. |
| 55 |
> |
The observed data yields in all signal regions are in good agreement with the SM background expectations; |
| 56 |
> |
see Ref.~\cite{ref:ss} for the full quantitative results. The signal region that is most sensitive to |
| 57 |
> |
bottom squark pair production with $\tilde{b}\to t \chim$ depicted in Fig.~\ref{fig:diagrams}(d) |
| 58 |
> |
has at least four jets, \met\ $>$ 120 GeV and |
| 59 |
> |
$H_T$ $>$ 200 GeV. In this region we observe 1 event in data and predict 2.22 $\pm$ 0.96 events. |
| 60 |
> |
The results are used to exclude a region of the model parameter space in Fig.~\ref{fig:ss_interpretation}(a), |
| 61 |
> |
which demonstrates that our search probes bottom squarks with masses up to 450 GeV. |
| 62 |
> |
Naturalness considerations favor a bottom squark with mass not exceeding 500--700 GeV, similar to the constraint |
| 63 |
> |
on the top squark mass. |
| 64 |
> |
Several additional interpretations for models with gluino-mediated top and |
| 65 |
|
bottom squark production are presented in Ref.~\cite{ref:ss}. |
| 66 |
|
|
| 67 |
< |
\begin{figure*} |
| 48 |
< |
\centering |
| 49 |
< |
%\begin{center} |
| 50 |
< |
\begin{tabular}{cc} |
| 51 |
< |
\subfloat[] {\includegraphics[width=0.5\textwidth]{HCPPlots/SS_B1.pdf}} & |
| 52 |
< |
\subfloat[] {\includegraphics[width=0.4\textwidth]{HCPPlots/T2bb_interpretation.pdf}} \\ |
| 53 |
< |
\end{tabular} |
| 54 |
< |
\caption{ |
| 55 |
< |
Interpretation of the results of the search in (a) the same-sign dilepton final state for |
| 56 |
< |
bottom squark pair production with $\tilde{b}\to t\chip$ depicted in Fig.~\ref{fig:diagrams}(d), and (b) |
| 57 |
< |
the all-hadronic final state for bottom squark pair production with $\tilde{b}\to b\lsp$ depicted in Fig.~\ref{fig:diagrams}(c). |
| 58 |
< |
\label{fig:ss_interpretation} |
| 59 |
< |
} |
| 60 |
< |
%\end{center} |
| 61 |
< |
\end{figure*} |
| 67 |
> |
%\input{ss_table.tex} |
| 68 |
|
|
| 69 |
+ |
%compared to the SM background expectations in |
| 70 |
+ |
%Table~\ref{tab:ss}. Good agreement is observed between the data and the expected background in all signal regions. |
| 71 |
|
|
| 72 |
|
%\begin{table} |
| 73 |
|
%\centering |
| 84 |
|
%\vspace*{5cm} % with the correct table height |
| 85 |
|
%\end{table} |
| 86 |
|
|
| 79 |
– |
|
| 80 |
– |
\begin{table*} |
| 81 |
– |
\centering |
| 82 |
– |
\caption{\label{tab:ss} Summary of the results of the search in the same-sign dilepton final state. |
| 83 |
– |
Several signal regions (SR) are indicated, including the kinematic requirements, the prediction of the three background (BG) contributions, |
| 84 |
– |
the total background, and the observed yield in data. The jet multiplicity requirement in the first row includes both b-tagged and untagged jets. The uncertainty includes the statistical and systematic components.} |
| 85 |
– |
\tabcolsep 2.7pt |
| 86 |
– |
\begin{scriptsize} |
| 87 |
– |
\begin{tabular}{l|c|c|c|c|c|c|c|c|c} |
| 88 |
– |
\hline |
| 89 |
– |
\hline |
| 90 |
– |
& SR0 & SR1 & SR2 & SR3 & SR4 & SR5 & SR6 & SR7 & SR8 \\ |
| 91 |
– |
\hline |
| 92 |
– |
No. of jets & $\geq 2$ & $\geq 2$ & $\geq 2$ & $\geq 4$ & $\geq 4$ & $\geq 4$ & $\geq 4$ & $\geq 3$ & $\geq 4$ \\ |
| 93 |
– |
No. of btags & $\geq 2$ & $\geq 2$ & $\geq 2$ & $\geq 2$ & $\geq 2$ & $\geq 2$ & $\geq 2$ & $\geq 3$ & $\geq 2$ \\ |
| 94 |
– |
Lepton charges & $++/--$ & $++/--$ & $++$ & $++/--$ & $++/--$ & $++/--$ & $++/--$ & $++/--$ & $++/--$ \\ |
| 95 |
– |
\met & $> 0$ GeV & $> 30$ GeV & $> 30$ GeV & $> 120$ GeV & $> 50$ GeV & $> 50$ GeV & $> 120$ GeV & $> 50$ GeV & $> 0$ GeV \\ |
| 96 |
– |
$H_T$ & $> 80$ GeV & $> 80$ GeV & $> 80$ GeV & $> 200$ GeV & $> 200$ GeV & $> 320$ GeV & $> 320$ GeV & $> 200$ GeV & $> 320$ GeV \\ |
| 97 |
– |
\hline |
| 98 |
– |
Charge-flip BG & $3.35 \pm 0.67$ & $2.70 \pm 0.54$ & $1.35 \pm 0.27$ & $0.04 \pm 0.01$ & $0.21 \pm 0.05$ & $0.14 \pm 0.03$ & $0.04 \pm 0.01$ & $0.03 \pm 0.01$ & $0.21 \pm 0.05$\\ |
| 99 |
– |
Fake BG & $24.77 \pm 12.62$ & $19.18 \pm 9.83$ & $9.59 \pm 5.02$ & $0.99 \pm 0.69$ & $4.51 \pm 2.85$ & $2.88 \pm 1.69$ & $0.67 \pm 0.48$ & $0.71 \pm 0.47$ & $4.39 \pm 2.64$ \\ |
| 100 |
– |
Rare SM BG & $11.75 \pm 5.89$ & $10.46 \pm 5.25$ & $6.73 \pm 3.39$ & $1.18 \pm 0.67$ & $3.35 \pm 1.84$ & $2.66 \pm 1.47$ & $1.02 \pm 0.60$ & $0.44 \pm 0.39$ & $3.50 \pm 1.92$ \\ |
| 101 |
– |
\hline |
| 102 |
– |
Total BG & $39.87 \pm 13.94$ & $32.34 \pm 11.16$ & $17.67 \pm 6.06$ & $2.22 \pm 0.96$ & $8.07 \pm 3.39$ & $5.67 \pm 2.24$ & $1.73 \pm 0.77$ & $1.18 \pm 0.61$ & $8.11 \pm 3.26$ \\ |
| 103 |
– |
Event yield & 43 & 38 & 14 & 1 & 10 & 7 & 1 & 1 & 9 \\ |
| 104 |
– |
\hline |
| 105 |
– |
% $N_{{UL}}$ (13\% unc.) & 27.2 &26.0 &9.9 &3.6 &10.8 &8.6 &3.6 &3.7 &9.6 \\ |
| 106 |
– |
% $N_{{UL}}$ (20\% unc.) & 28.2 &27.2 &10.2 &3.6 &11.2 &8.9 &3.7 &3.8 &9.9 \\ |
| 107 |
– |
% $N_{{UL}}$ (30\% unc.) & 30.4 &29.6 &10.7 &3.8 &12.0 &9.6 &3.9 &4.0 &10.5 \\ |
| 108 |
– |
\hline |
| 109 |
– |
\end{tabular} |
| 110 |
– |
\end{scriptsize} |
| 111 |
– |
\end{table*} |
