%%    TEMPLATE for articles submitted to the full-tex econf proceedings
%%     
%%
%%     Please do not remove lines commented out with %+
%%           these are for the editors' use.
%%
%%     Questions?  Send email to :  mpeskin@slac.stanford.edu
%%   

\documentclass[12pt]{article}
\usepackage{epsfig}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  Do not change these:
\textwidth=6.0in  \textheight=8.25in

%%  Adjust these for your printer:
\leftmargin=-0.3in   \topmargin=-0.20in


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%  personal abbreviations and macros
%    the following package contains macros used in this document:
\input econfmacros.tex
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  To include an item in the INDEX of the conference volume,
%           flag it with    \index{<item name>}
%  The use of this macro is illustrated in the text.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\def\Title#1{\begin{center} {\Large {\bf #1} } \end{center}}

\begin{document}

\Title{Search for Supersymmetry in Final States with a Single Lepton, B-jets and
Missing Transverse Energy at the CMS Experiment}

\bigskip\bigskip

%+\addtocontents{toc}{{\it D. Reggiano}}
%+\label{ReggianoStart}

\begin{raggedright}  

{\it Niklas Pietsch\index{Pietsch, N.}\\
Department of Experimental Physics\\
University of Hamburg\\
D-22761 Hamburg, GERMANY}
\bigskip\bigskip
\end{raggedright}

\section{Introduction}

Searches for new physics in states with third generation quarks at the Large
Hadron Collider are motivated by various extensions of the Standard Model (SM).
Among these, supersymmetric models are regarded as attractive as they resolve
the hierarchy problem and may yield the unification of the electroweak and strong interactions.
Supersymmetry (SUSY) (see e.g.~\cite{Martin:1997ns}) predicts that for each Standard Model particle there exists a
partner particle (sparticle) with identical gauge quantum numbers, but a spin
differing by 1/2. Assuming $R$-parity conservation, sparticles are produced in pairs
and their decay chains terminate with the lightest supersymmetric particle (LSP), which is stable.
In proton-proton collisions predominantly colored sparticles will be
produced. In scenarios with light top and bottom squarks this may result in an excess of events
with a large b-jet multiplicity.\\
The analysis outlined in the following is based on data recorded at the CMS experiment in proton-proton
collisions at a center of mass energy of of $\sqrt{s}=7\,\textmd{TeV}$ during 2011, corresponding to an integrated
luminosity of $4.96~\textmd{fb}^{-1}$. The complete CMS publication and a description of the CMS
detector can be found elsewhere \cite{SUS11028,Chatrchyan:2008aa}.

\section{Event Selection and Background Estimation}

Events with exactly one isolated muon or electron with a transverse momentum of $p_{T}>20\,\textmd{GeV}$
and at least four jets with $p_{T}>40\,\textmd{GeV}$ reconstructed with the anti-$k_{T}$ algorithm with
a distance parameter of 0.5 are selected. In addition the missing transverse energy
($E_{T}^{miss}$) is required to be larger than 60\,GeV and $H_{T}$, which is defined as the scalar
sum of the $p_{T}$ of the selected jets, to be larger than 375\,GeV. Jets are identified as b-jets
if they have at least two tracks with an impact parameter significance greater than 3.3 \cite{BTV11004}.
The decay of colored sparticles is expected to result in a large hadronic activity (as measured by $H_{T}$)
and a significant amount of $E_{T}^{miss}$, which can be quantified by $Y_{MET}\equiv E_{T}^{miss}/\sqrt{H_{T}}$.
As for the main background, $t\bar{t}$ events, $H_{T}$ and $Y_{MET}$ are nearly uncorrelated,
the number of background events in a signal region at large values of $E_{T}^{miss}$ and $Y_{MET}$ is
estimated from data in background enriched control regions at low values of $E_{T}^{miss}$ or $Y_{MET}$ using a
factorization method. 

\section{Results and Interpretation}

No excess of events has been observed. The obtained results are used to set limits upon the parameters of different SUSY
models using the CLs technique \cite{Read:2002hq}. Limits for the Constrained Minimal Supersymmetric 
Standard Model (cMSSM) with $\tan\beta=10$, $A_{0}=0$, and $\mu>0$ and a heavy flavor simplified model after the
additional requirement of at least one b-jet and at least three b-jets, respectively, are shown in Fig.~\ref{fig:limits}.
The simplified model covers the pair production of gluon partner particles that decay into a $t\bar{t}$ pair and the LSP.
\begin{figure}[htb]
\begin{center}
\epsfig{file=CMSSM.eps,height=2in}
\epsfig{file=T1tttt.eps,height=2in}
\caption{The 95\% CL limits for the cMSSM and a heavy flavor simplified model.}
\label{fig:limits}
\end{center}
\end{figure}

\begin{thebibliography}{99}
\bibitem{Martin:1997ns} 
  S.~P.~Martin,
  ``A Supersymmetry primer,''
  arXiv:hep-ph/9709356v6.
\bibitem{SUS11028}
  CMS Collaboration,
  PAS SUS-11-028 (2012).
\bibitem{Chatrchyan:2008aa} 
  CMS Collaboration,
  ``The CMS experiment at the CERN LHC,''
  JINST {\bf 3}, S08004 (2008).
\bibitem{BTV11004}
  CMS Collaboration,
  PAS BTV-11-004 (2012).
\bibitem{Read:2002hq} 
  A.~L.~Read,
  J.\ Phys.\ G G {\bf 28}, 2693 (2002).
\end{thebibliography}
 
\end{document}

