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Presentations / DIS2015 / CPV / mchrzasz.tex
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\title[Recent BaBar results on CP violation in B-meson decays]{ Recent BaBar results on CP violation in B-meson decays}        
\author{Marcin Chrz\k{a}szcz$^{1}$ \\ \footnotesize{on behalf of the BaBar collaboration}}   
\institute{$^1$~University of Zurich \\{~}\\  Deep-Inelastic Scattering 2015 }              
\date{\today}                                                                               
\begin{document}                                                                            
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\frame[plain]{\titlepage}                                                                   
\author{Marcin Chrz\k{a}szcz}                                                               
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\institute{~(UZH)}                                                                          



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\section{BaBar Detector}
\begin{frame}\frametitle{BaBar Detector}

\begin{columns}
\column{2.5in}
\begin{itemize}
\item PEP-II, an asymmetric $\Pelectron \APelectron$ collider.
\item Operating mostly at $\PUpsilon(4S)$ threshold.
\end{itemize}
\includegraphics[width=0.95\textwidth]{images/bbr_det.png}
\column{2.5in}
\includegraphics[width=0.95\textwidth]{images/bbr_lumi.png}

\end{columns}
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\end{frame}

\begin{frame}\frametitle{B factories}

\begin{columns}
\column{2.5in}

\includegraphics[width=0.95\textwidth]{images/upsilon1.png}\\
\includegraphics[width=0.95\textwidth]{images/topo.png}
\column{2.5in}
\begin{itemize}
\item $\PB$ mesons produced in a clean environment.
\item Just above the $m(\PB \PB)$ threshold.
\end{itemize}
\includegraphics[width=0.95\textwidth]{images/ee_col.png}

\end{columns}
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\end{frame}
       
\section{CP violation in $\PB \APB$ mixing}       
       
\begin{frame}\frametitle{$\PBzero \APBzero$ mixing}

\begin{itemize}
\item Neutral mesons couple to their anti particles via weak interactions.

\end{itemize}

\begin{columns}
\column{3.4in}

\begin{itemize}
\item $\PBzero \Leftrightarrow \APBzero$, $\PB s\Leftrightarrow \APBs$, $\PK \Leftrightarrow \APK$.
\item We can writhe the weak eigenstates as:
\end{itemize}
\begin{equation*}
\ket{B_{L/H}} = \dfrac{1}{\sqrt{p^2+q^2}} (p \ket{\PBzero} \pm q \ket{\APBzero})
\end{equation*}
\begin{itemize}
\item Then the CP asymmetry can can be written as:
\end{itemize}
\begin{equation*}
A_{CP} = \dfrac{\mathcal{P}(\APBzero \to \PBzero) - \mathcal{P}(\PBzero \to \APBzero) }{\mathcal{P}(\APBzero \to \PBzero) + \mathcal{P}(\PBzero \to \APBzero)}\approx 2(1-|\frac{q}{p}|)
\end{equation*}
\column{1.5in}
\begin{center}
\includegraphics[width=0.99\textwidth]{images/Bmixing_dia.png}
\end{center}

\end{columns}
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\begin{itemize}
\item $\PUpsilon(4S)$ has an anti-symmetric state: $\dfrac{1}{\sqrt{2}} (\PBzero(t_1) \APBzero(t_2) -  \APBzero(t_1) \PBzero(t_2)$
\item One $\PB$ is a specific flavour state tags the other one.
\end{itemize}

\end{frame}      
       
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\begin{frame}\frametitle{Inclusive dilepton measurement}
\begin{itemize}
\item $\PB$ mesons decay in $\sim 10\%$ semileptonicaly. 
\item Charge of lepton determines the $\PB$ meson flavour.
\item If one observes same sign leptons $\to$ mixing occurred:
\end{itemize}
\begin{columns}

\column{0.5in}
{~}
\column{2.5in}
\begin{itemize}
\item $\Plepton^- \Plepton^{+}$: no mixing
\item $\Plepton^- \Plepton^{-}$: $\PBzero \to \APBzero$.
\item $\Plepton^+ \Plepton^{+}$: $\APBzero \to \PBzero$.
\end{itemize}
\column{2in}
\includegraphics[width=0.65\textwidth]{images/semillep.png}

\end{columns}
\begin{itemize}
\item Writing down the mixing provabilities~(time integrated):
\end{itemize}
\begin{equation*}
\mathcal{P}^{\pm \pm} \propto (1 \pm A_{CP}) \chi_d
\end{equation*}
\begin{equation*}
\mathcal{P}^{\pm \mp} \propto (1 -\chi_d)
\end{equation*}



\end{frame}      
        
      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%5
\begin{frame}\frametitle{Detector effects}
\begin{footnotesize}


\begin{itemize}
\item Detector is not a perfect device $\to$ Introduced charge asymmetries $a_{\Plepton_j}$ for each $\Plepton_j$.
\item $\PUpsilon(4S)$ also goes to $\PBplus \PBminus$. Contribution: $r_B = N_{\PB^+ \PB^-}/N_{\PBzero \APBzero}$.
\item Time integrated probability gets modified:

\begin{align*}
\mathcal{P}^{\pm \pm} \propto (1 \pm a_{\Plepton_1} \pm a_{\Plepton_2} \pm A_{CP}) \chi_d \\
\mathcal{P}^{\pm \mp} \propto (1 -\chi_d + r_B)(1 \pm a_{\Plepton_1} \mp a_{\Plepton_2} )
\end{align*}
\item Summing over all events in $\Plepton_1 \Plepton_2 \in \lbrace \Pe \Pe, \Pe \Pmu, \Pmu \Pe, \Pmu \Pmu \rbrace$ categories:

\begin{align*}
N^{\pm \pm}_{\Plepton_1 \Plepton_2} = 1/2 N^0_{\Plepton_1 \Plepton_2} (1 \pm a_{\Plepton_1} \pm a_{\Plepton_2} \pm A_{CP}) \chi_d^{\Plepton_1 \Plepton_2}\\
N^{\pm \mp}_{\Plepton_1 \Plepton_2}= 1/2 N^0_{\Plepton_1 \Plepton_2} (1 -\chi_d^{\Plepton_1 \Plepton_2} + r_B)(1 \pm a_{\Plepton_1} \mp a_{\Plepton_2} )
\end{align*}

\item We got 16 observables, and 13 unknowns. $a_{\Plepton_j}$ highly correlated.
\item Adding events containing only single electron for $a_{\Pe}$ constrain.
\item 17 observables as input to $\chi^2$ fit, extracting: $A_{CP}$, 4 signal yields,\\ 4 efficiency asymmetries,  4 mixing probabilities.
\end{itemize}




\end{footnotesize}

\end{frame}      
         
       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%5
\begin{frame}\frametitle{Fit results}
\begin{center}
\begin{footnotesize}

\begin{tabular}{c c c c}
\hline \hline  
\multicolumn{2}{c}{$A_{CP} = (-3.9 \pm 3.5)\times 10^{-3}$} & \multicolumn{2}{c}{ \includegraphics[height=0.5cm]{images/Babar_with_banner.jpg}~\href{http://arxiv.org/abs/1411.1842}{PRL 114, 081801 (2015)} }\\ \hline %\hline
$N^0_{\Pe\Pe}$ & $N^0_{\Pe\Pmu}$ & $N^0_{\Pmu\Pe}$ & $N^0_{\Pmu\Pmu}$ \\ 
$430875 \pm 515$ & $365343 \pm 429$ & $458200 \pm 480$ & $268077 \pm 381$ \\
$\chi_d^{\Pe\Pe}$ & $\chi_d^{\Pe\Pmu}$ & $\chi_d^{\Pmu\Pe}$ & $\chi_d^{\Pmu\Pmu}$ \\ 
$0.2248 \pm 0.0006$ & $0.1769 \pm 0.0006$ & $0.1754 \pm 0.0005$ &  $0.2032 \pm 0.0007$ \\
$a^{\Pe 1}$ & $a^{\Pe 2}$ & $a^{\Pmu 1}$ & $a^{\Pmu 2}$ \\ 
$0.0034 \pm 0.0006$ & $0.0030 \pm 0.006$ & $-0.0056 \pm 0.0011$ & $-0.0065 \pm 0.0011$ \\ \hline
\end{tabular}
{~}\\
\begin{columns}
\column{0.5in}{~}
\column{2.5in}
\includegraphics[width=0.75\textwidth]{images/pull.png}
\begin{itemize}
\item Result $A_{CP} = (-3.9 \pm 3.5 \pm 1.9 )\times 10^{-3}$ in agreement with SM.
\end{itemize}
\column{2.5in}
\includegraphics[width=0.76\textwidth]{images/hfag.png}
\end{columns}

\end{footnotesize}
\end{center}


\end{frame}             
       
      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%5
\begin{frame}\frametitle{Flavour-changing neutral current}
\begin{itemize}
\item CKM structure in SM allows only the charged interactions to change flavour.
\item One can escape the CKM structure and produce $\Pbottom \to \Pstrange$ and $\Pbottom \to \Pdown$ only at loop level.
\begin{itemize}
\item This kind of processes are suppressed by the GIM in SM $\to$~Rare decays.
\end{itemize}
\item LHCb already sees a $3.7~\sigma$ deviation in the angular observables in $\PBzero \to \PKstar \Pmuon \APmuon$. See my talk LINK.
\item Here we present CP observables in $b \to s \Pphoton$ and $b \to s \Plepton \Plepton$ decays.
\end{itemize}
      
      
  \end{frame}    
  
  
      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%5
\begin{frame}\frametitle{Flavour-changing neutral current}
\begin{itemize}
\item CKM structure in SM allows only the charged interactions to change flavour.
\item One can escape the CKM structure and produce $\Pbottom \to \Pstrange$ and $\Pbottom \to \Pdown$ only at loop level.
\begin{itemize}
\item This kind of processes are suppressed by the GIM in SM $\to$~Rare decays.
\end{itemize}
\item LHCb already sees a $3.7~\sigma$ deviation in the angular observables in $\PBzero \to \PKstar \Pmuon \APmuon$. See my talk LINK.
\item Here we present CP observables in $b \to s \Pphoton$ and $b \to s \Plepton \Plepton$ decays.
\end{itemize}
      
      
  \end{frame}     
  
  
  
  
  
  
  
              
\end{document}