claudioc/OSNote2010/eventsel.tex

\section{Event Preselection}
\label{sec:eventSel}
%{\color{red} This needs to be fixed up -- probably many mistakes present.}\\
As mentioned in the introduction, the preselection is based on the 
$t\bar{t}$ analysis.  We select events with two opposite sign isolated
leptons ($ee$, $e\mu$, or $\mu\mu$); one of the leptons must 
have $P_T > 20$ GeV,
the other one must have $P_T > 10$ GeV. Events consistent with $Z$ are rejected.
In case of events with 
more than two such leptons, we select the pair that maximizes the scalar 
sum of lepton $P_T$'s.
There must be two JPT
jets of $P_T > 30$ GeV and $|\eta| < 2.5$; the scalar sum of the 
$P_T$ of all such jets must exceed 100 GeV; jets must pass
{\tt caloJetId} and be separated by $\Delta R >$ 0.4 from any 
lepton passing the selection.
Finally $\met > 50$ GeV (we use tcMet). More details are given in the subsections below.

\subsection{Event Cleanup}
\label{sec:cleanup}
\begin{itemize}
\item Scraping cut: if there are $\geq$ 10 tracks, require at
least 25\% of them to be high purity.
\item Require at least one good vertex:
\begin{itemize}
\item not fake
\item ndof $>$ 4
\item $|\rho| < 2$ cm
\item $|z| < 24$ cm.  
\end{itemize}
\end{itemize}


\subsection{Muon Selection}
\label{sec:muon}

Muon candidates are RECO muon objects passing the following
requirements:
\begin{itemize}

\item $|\eta| < 2.4$.

\item Global Muon and Tracker Muon.

\item $\chi^2$/ndof of global fit $<$ 10.

\item At least 11 hits in the tracker fit.

\item Transverse impact parameter with respect to the beamspot $<$ 200 $\mu$m.

\item $Iso \equiv $ $E_T^{\rm iso}$/Max(20 GeV, $P_T$) $<$ 0.15.  
$E_T^{\rm iso}$
is defined as the sum of transverse energy/momentum deposits in ecal,
hcal, and tracker, in a cone of 0.3.

\item At least one of the hits from the 
standalone muon must be used in the global fit.

\item Require tracker $\Delta P_T/P_T < 0.1$. This cut was not in the original top analysis.
It is motivated by the observation of
poorly measured muons in data with large
relative $P_T$ uncertainty, giving significant contributions to the \met.
%{\color{red} This is not applied to the 11 pb iteration.}


\end{itemize}


\subsection{Electron Selection}
\label{sec:electron}

Electron candidates are RECO GSF electrons passing the following
requirements:

\begin{itemize}

\item $P_T > 10$ GeV.  (The $t\bar{t}$ analysis uses 20 GeV but for
completeness we calculate FR down to 10 GeV).

\item $|\eta| < 2.5$.

\item SuperCluster $E_T > 10$ GeV.  

\item The electron must be ecal seeded.

\item VBTF90 identification\cite{ref:vbtf}.

\item Transverse impact parameter with respect to the beamspot $<$ 400 $\mu$m.

\item $Iso \equiv $ $E_T^{\rm iso}$/Max(20 GeV, $P_T$) $<$ 0.15.  
$E_T^{\rm iso}$
is defined as the sum of transverse energy/momentum deposits in ecal,
hcal, and tracker, in a 
cone of 0.3.  A 1 GeV pedestal is subtracted from the ecal energy 
deposition in the EB, however the ecal energy is never allowed to 
go negative.

\item Electrons with a tracker or global muon within $\Delta R$ of 
0.1 are vetoed.

\item The number of missing expected inner hits must be less than 
two\cite{ref:conv}.

\item Conversion removal via partner track finding: any electron
where an additional GeneralTrack is found with $Dist < 0.02$ cm 
and $\Delta \cot \theta < 0.02$ is vetoed\cite{ref:conv}.

\item Cleaning for ECAL spike (aka Swiss-Cross cleaning) has been applied
at the reconstruction level (CMSSW 38x).

\end{itemize}

\subsection{Invariant mass requirement}
\label{sec:zveto}

We remove $e^+e^-$ and $\mu^+ \mu^-$ events with invariant 
mass between 76 and 106 GeV.  We also remove events
with invariant mass $<$ 10 GeV, since this kinematical region is 
not well reprodced in CMS Monte Carlos.

In addition, we remove $Z \to \mu\mu\gamma$
candidates with the $\gamma$ collinear with one of the muons.  This is
done as follows:
if the ecal energy associated with one of the muons is greater than 6 GeV,
we add this energy to the momentum of the initial muon, and we recompute
the $\mu\mu$ mass.  If this mass is between 76 and 106 GeV, the event is rejected.


\subsection{Trigger Selection}
\label{sec:trigSel}

Because most of the triggers implemented in the 2nd half of the
2010 run were not implemented in the Monte Carlo, no trigger
selection is applied on Monte Carlo data.  As discussed in 
Section~\ref{sec:trgEff}, a trigger efficiency weight is applied
to each event, based on the trigger efficiencies measured on data.
Trigger efficiency weights are very close to 1.

%For data, we require the logical OR of all (or most?) unprescaled
%single and double lepton triggers that were deployed during the 2010
%run.  These are:
%{\color{red} Here we need to list the triggers, somehow.}

For data, we use a cocktail of unprescaled single 
and double lepton triggers. An event
in the $ee$ final state is required to pass at least 1 
single- or double-electron trigger, a
$\mu\mu$ event is required to pass at least 1 single 
or double-muon trigger, while an $e\mu$ event
is required to pass at least 1 single-muon, single-electron, 
or $e-\mu$ cross trigger. 
% We currently
% do not require MC events to pass any triggers.


\begin{itemize}
\item single-muon triggers
  \begin{itemize}
  \item \verb=HLT_Mu5=
  \item \verb=HLT_Mu7=       
  \item \verb=HLT_Mu9=        
  \item \verb=HLT_Mu11=      
  \item \verb=HLT_Mu13_v1=    
  \item \verb=HLT_Mu15_v1=    
  \item \verb=HLT_Mu17_v1=    
  \item \verb=HLT_Mu19_v1=    
  \end{itemize}
\item double-muon triggers
  \begin{itemize}
  \item \verb=HLT_DoubleMu3=
  \item \verb=HLT_DoubleMu3_v2=
  \item \verb=HLT_DoubleMu5_v1=
  \end{itemize}
\item single-electron triggers
  \begin{itemize}
  \item \verb=HLT_Ele10_SW_EleId_L1R=
  \item \verb=HLT_Ele10_LW_EleId_L1R=
  \item \verb=HLT_Ele10_LW_L1R=
  \item \verb=HLT_Ele10_SW_L1R=
  \item \verb=HLT_Ele15_SW_CaloEleId_L1R=
  \item \verb=HLT_Ele15_SW_EleId_L1R=
  \item \verb=HLT_Ele15_SW_L1R=
  \item \verb=HLT_Ele15_LW_L1R=
  \item \verb=HLT_Ele17_SW_TightEleId_L1R=
  \item \verb=HLT_Ele17_SW_TighterEleId_L1R_v1=
  \item \verb=HLT_Ele17_SW_CaloEleId_L1R=
  \item \verb=HLT_Ele17_SW_EleId_L1R=
  \item \verb=HLT_Ele17_SW_LooseEleId_L1R=
  \item \verb=HLT_Ele17_SW_TighterEleIdIsol_L1R_v2=
  \item \verb=HLT_Ele20_SW_L1R=
  \item \verb=HLT_Ele22_SW_TighterEleId_L1R_v2=
  \item \verb=HLT_Ele32_SW_TightCaloEleIdTrack_L1R_v1=
  \item \verb=HLT_Ele32_SW_TighterEleId_L1R_v2=
  \item \verb=HLT_Ele27_SW_TightCaloEleIdTrack_L1R_v1=
  \item \verb=HLT_Ele22_SW_TighterCaloIdIsol_L1R_v2=
  \item \verb=HLT_Ele22_SW_TighterEleId_L1R_v3=
  \item \verb=HLT_Ele22_SW_TighterCaloIdIsol_L1R_v2=
  \end{itemize}
\item double-electron triggers
  \begin{itemize}
  \item \verb=HLT_DoubleEle15_SW_L1R_v1=                
  \item \verb=HLT_DoubleEle17_SW_L1R_v1=  
  \item \verb=HLT_Ele17_SW_TightCaloEleId_Ele8HE_L1R_v1=
  \item \verb=HLT_Ele17_SW_TightCaloEleId_SC8HE_L1R_v1=
  \item \verb=HLT_DoubleEle10_SW_L1R=
  \item \verb=HLT_DoubleEle5_SW_L1R=
  \end{itemize}
\item e-$\mu$ cross triggers
  \begin{itemize}
  \item \verb=HLT_Mu5_Ele5_v1=
  \item \verb=HLT_Mu5_Ele9_v1=
  \item \verb=HLT_Mu11_Ele8_v1=
  \item \verb=HLT_Mu8_Ele8_v1=
  \item \verb=HLT_Mu5_Ele13_v2=
  \item \verb=HLT_Mu5_Ele17_v1=
  \end{itemize}
\end{itemize}
Revision:	1.11
Committed:	Thu Nov 11 12:34:17 2010 UTC (14 years, 6 months ago) by claudioc
Content type:	application/x-tex
Branch:	MAIN
Changes since 1.10:	+26 -12 lines
Log Message:	changes after talking to Ben
#	Content
1	\section{Event Preselection}
2	\label{sec:eventSel}
3	%{\color{red} This needs to be fixed up -- probably many mistakes present.}\\
4	As mentioned in the introduction, the preselection is based on the
5	$t\bar{t}$ analysis. We select events with two opposite sign isolated
6	leptons ($ee$, $e\mu$, or $\mu\mu$); one of the leptons must
7	have $P_T > 20$ GeV,
8	the other one must have $P_T > 10$ GeV. Events consistent with $Z$ are rejected.
9	In case of events with
10	more than two such leptons, we select the pair that maximizes the scalar
11	sum of lepton $P_T$'s.
12	There must be two JPT
13	jets of $P_T > 30$ GeV and $\|\eta\| < 2.5$; the scalar sum of the
14	$P_T$ of all such jets must exceed 100 GeV; jets must pass
15	{\tt caloJetId} and be separated by $\Delta R >$ 0.4 from any
16	lepton passing the selection.
17	Finally $\met > 50$ GeV (we use tcMet). More details are given in the subsections below.
18
19	\subsection{Event Cleanup}
20	\label{sec:cleanup}
21	\begin{itemize}
22	\item Scraping cut: if there are $\geq$ 10 tracks, require at
23	least 25\% of them to be high purity.
24	\item Require at least one good vertex:
25	\begin{itemize}
26	\item not fake
27	\item ndof $>$ 4
28	\item $\|\rho\| < 2$ cm
29	\item $\|z\| < 24$ cm.
30	\end{itemize}
31	\end{itemize}
32
33
34	\subsection{Muon Selection}
35	\label{sec:muon}
36
37	Muon candidates are RECO muon objects passing the following
38	requirements:
39	\begin{itemize}
40
41	\item $\|\eta\| < 2.4$.
42
43	\item Global Muon and Tracker Muon.
44
45	\item $\chi^2$/ndof of global fit $<$ 10.
46
47	\item At least 11 hits in the tracker fit.
48
49	\item Transverse impact parameter with respect to the beamspot $<$ 200 $\mu$m.
50
51	\item $Iso \equiv $ $E_T^{\rm iso}$/Max(20 GeV, $P_T$) $<$ 0.15.
52	$E_T^{\rm iso}$
53	is defined as the sum of transverse energy/momentum deposits in ecal,
54	hcal, and tracker, in a cone of 0.3.
55
56	\item At least one of the hits from the
57	standalone muon must be used in the global fit.
58
59	\item Require tracker $\Delta P_T/P_T < 0.1$. This cut was not in the original top analysis.
60	It is motivated by the observation of
61	poorly measured muons in data with large
62	relative $P_T$ uncertainty, giving significant contributions to the \met.
63	%{\color{red} This is not applied to the 11 pb iteration.}
64
65
66	\end{itemize}
67
68
69
70	\subsection{Electron Selection}
71	\label{sec:electron}
72
73	Electron candidates are RECO GSF electrons passing the following
74	requirements:
75
76	\begin{itemize}
77
78	\item $P_T > 10$ GeV. (The $t\bar{t}$ analysis uses 20 GeV but for
79	completeness we calculate FR down to 10 GeV).
80
81	\item $\|\eta\| < 2.5$.
82
83	\item SuperCluster $E_T > 10$ GeV.
84
85	\item The electron must be ecal seeded.
86
87	\item VBTF90 identification\cite{ref:vbtf}.
88
89	\item Transverse impact parameter with respect to the beamspot $<$ 400 $\mu$m.
90
91	\item $Iso \equiv $ $E_T^{\rm iso}$/Max(20 GeV, $P_T$) $<$ 0.15.
92	$E_T^{\rm iso}$
93	is defined as the sum of transverse energy/momentum deposits in ecal,
94	hcal, and tracker, in a
95	cone of 0.3. A 1 GeV pedestal is subtracted from the ecal energy
96	deposition in the EB, however the ecal energy is never allowed to
97	go negative.
98
99	\item Electrons with a tracker or global muon within $\Delta R$ of
100	0.1 are vetoed.
101
102	\item The number of missing expected inner hits must be less than
103	two\cite{ref:conv}.
104
105	\item Conversion removal via partner track finding: any electron
106	where an additional GeneralTrack is found with $Dist < 0.02$ cm
107	and $\Delta \cot \theta < 0.02$ is vetoed\cite{ref:conv}.
108
109	\item Cleaning for ECAL spike (aka Swiss-Cross cleaning) has been applied
110	at the reconstruction level (CMSSW 38x).
111
112	\end{itemize}
113
114	\subsection{Invariant mass requirement}
115	\label{sec:zveto}
116
117	We remove $e^+e^-$ and $\mu^+ \mu^-$ events with invariant
118	mass between 76 and 106 GeV. We also remove events
119	with invariant mass $<$ 10 GeV, since this kinematical region is
120	not well reprodced in CMS Monte Carlos.
121
122	In addition, we remove $Z \to \mu\mu\gamma$
123	candidates with the $\gamma$ collinear with one of the muons. This is
124	done as follows:
125	if the ecal energy associated with one of the muons is greater than 6 GeV,
126	we add this energy to the momentum of the initial muon, and we recompute
127	the $\mu\mu$ mass. If this mass is between 76 and 106 GeV, the event is rejected.
128
129
130	\subsection{Trigger Selection}
131	\label{sec:trigSel}
132
133	Because most of the triggers implemented in the 2nd half of the
134	2010 run were not implemented in the Monte Carlo, no trigger
135	selection is applied on Monte Carlo data. As discussed in
136	Section~\ref{sec:trgEff}, a trigger efficiency weight is applied
137	to each event, based on the trigger efficiencies measured on data.
138	Trigger efficiency weights are very close to 1.
139
140	%For data, we require the logical OR of all (or most?) unprescaled
141	%single and double lepton triggers that were deployed during the 2010
142	%run. These are:
143	%{\color{red} Here we need to list the triggers, somehow.}
144
145	For data, we use a cocktail of unprescaled single
146	and double lepton triggers. An event
147	in the $ee$ final state is required to pass at least 1
148	single- or double-electron trigger, a
149	$\mu\mu$ event is required to pass at least 1 single
150	or double-muon trigger, while an $e\mu$ event
151	is required to pass at least 1 single-muon, single-electron,
152	or $e-\mu$ cross trigger.
153	% We currently
154	% do not require MC events to pass any triggers.
155
156
157
158
159
160
161
162
163
164	\begin{itemize}
165	\item single-muon triggers
166	\begin{itemize}
167	\item \verb=HLT_Mu5=
168	\item \verb=HLT_Mu7=
169	\item \verb=HLT_Mu9=
170	\item \verb=HLT_Mu11=
171	\item \verb=HLT_Mu13_v1=
172	\item \verb=HLT_Mu15_v1=
173	\item \verb=HLT_Mu17_v1=
174	\item \verb=HLT_Mu19_v1=
175	\end{itemize}
176	\item double-muon triggers
177	\begin{itemize}
178	\item \verb=HLT_DoubleMu3=
179	\item \verb=HLT_DoubleMu3_v2=
180	\item \verb=HLT_DoubleMu5_v1=
181	\end{itemize}
182	\item single-electron triggers
183	\begin{itemize}
184	\item \verb=HLT_Ele10_SW_EleId_L1R=
185	\item \verb=HLT_Ele10_LW_EleId_L1R=
186	\item \verb=HLT_Ele10_LW_L1R=
187	\item \verb=HLT_Ele10_SW_L1R=
188	\item \verb=HLT_Ele15_SW_CaloEleId_L1R=
189	\item \verb=HLT_Ele15_SW_EleId_L1R=
190	\item \verb=HLT_Ele15_SW_L1R=
191	\item \verb=HLT_Ele15_LW_L1R=
192	\item \verb=HLT_Ele17_SW_TightEleId_L1R=
193	\item \verb=HLT_Ele17_SW_TighterEleId_L1R_v1=
194	\item \verb=HLT_Ele17_SW_CaloEleId_L1R=
195	\item \verb=HLT_Ele17_SW_EleId_L1R=
196	\item \verb=HLT_Ele17_SW_LooseEleId_L1R=
197	\item \verb=HLT_Ele17_SW_TighterEleIdIsol_L1R_v2=
198	\item \verb=HLT_Ele20_SW_L1R=
199	\item \verb=HLT_Ele22_SW_TighterEleId_L1R_v2=
200	\item \verb=HLT_Ele32_SW_TightCaloEleIdTrack_L1R_v1=
201	\item \verb=HLT_Ele32_SW_TighterEleId_L1R_v2=
202	\item \verb=HLT_Ele27_SW_TightCaloEleIdTrack_L1R_v1=
203	\item \verb=HLT_Ele22_SW_TighterCaloIdIsol_L1R_v2=
204	\item \verb=HLT_Ele22_SW_TighterEleId_L1R_v3=
205	\item \verb=HLT_Ele22_SW_TighterCaloIdIsol_L1R_v2=
206	\end{itemize}
207	\item double-electron triggers
208	\begin{itemize}
209	\item \verb=HLT_DoubleEle15_SW_L1R_v1=
210	\item \verb=HLT_DoubleEle17_SW_L1R_v1=
211	\item \verb=HLT_Ele17_SW_TightCaloEleId_Ele8HE_L1R_v1=
212	\item \verb=HLT_Ele17_SW_TightCaloEleId_SC8HE_L1R_v1=
213	\item \verb=HLT_DoubleEle10_SW_L1R=
214	\item \verb=HLT_DoubleEle5_SW_L1R=
215	\end{itemize}
216	\item e-$\mu$ cross triggers
217	\begin{itemize}
218	\item \verb=HLT_Mu5_Ele5_v1=
219	\item \verb=HLT_Mu5_Ele9_v1=
220	\item \verb=HLT_Mu11_Ele8_v1=
221	\item \verb=HLT_Mu8_Ele8_v1=
222	\item \verb=HLT_Mu5_Ele13_v2=
223	\item \verb=HLT_Mu5_Ele17_v1=
224	\end{itemize}
225	\end{itemize}