\begin{titlepage}
   {\noindent HU-EP-10/43 \hfill \raggedleft TTP10-33\\
   DO-TH 10/05 \hfill \raggedleft SFB/CPP-10-68\\
   LPT-ORSAY/10-59   \hfill \raggedleft CPT-P040-2010\\
  }
  \vskip 2em
  {\centering \Huge \bf Anatomy of New Physics \\ in
    $\boldsymbol{B}$--$\boldsymbol{\overline{B}}$ mixing \\}
  \vskip 2.5em
  {\centering
    \large 
    A.~Lenz$^{a,b}$, U.~Nierste$^c$\\[0.6em]
    and \\[0.6em]
    J.~Charles$^d$, S.~Descotes-Genon$^e$, A.~Jantsch$^f$, C.~Kaufhold$^g$, H.~Lacker$^h$, S.~Monteil$^i$, V.~Niess$^i$\\[0.2em]
    [CKMfitter Group]\\
  }
    \vskip 2em \noindent
{\small \em $^{a}$Institut f\"ur Physik, Technische Universit\"at Dortmund, 
                   D-44221 Dortmund, Germany}\\[0.2cm]
{\small \em $^{b}$Institut f\"ur Theoretische Physik, Universit\"at Regensburg, 
                   D-93949 Regensburg, Germany,
                {e-mail: Alexander.Lenz@physik.uni-regensburg.de}} \\[0.2cm]
{\small \em $^{c}$Institut f\"ur Theoretische Teilchenphysik, Universit\"at Karlsruhe, Karlsruhe Insitute of Technology, 
                   D-76128 Karlsruhe, Germany,
                {e-mail: nierste@particle.uni-karlsruhe.de}} \\[0.2cm]
{\small \em $^{d}$Centre de Physique Th\'eorique, 
                   Campus de Luminy, 
                   Case 907, F-13288 Marseille Cedex 9, France
                   (UMR 6207 du CNRS associ\'ee aux
                   Universit\'es d'Aix-Marseille I et II et
                   Universit\'e du Sud Toulon-Var; laboratoire
                   affili\'e \`a la FRUMAM-FR2291),
                {e-mail: charles@cpt.univ-mrs.fr}} \\[0.2cm]
{\small \em $^{e}$Laboratoire de Physique Theorique d'Orsay,
                  UMR8627, CNRS/Univ. Paris-Sud 11, 91405 Orsay Cedex, France,
                {email: sebastien.descotes-genon@th.u-psud.fr}} \\[0.2cm]
{\small \em $^{f}$Max-Planck-Institut f\"ur Physik 
                   (Werner-Heisenberg-Institut),
		   F\"ohringer Ring 6, 80805 M\"un\-chen, Germany,
                {e-mail: jantsch@mppmu.mpg.de}} \\[0.2cm]
{\small \em $^{g}$Laboratoire d'Annecy-Le-Vieux de Physique des Particules, 
                   9 Chemin de Bellevue, BP 110, F-74941
                   Annecy-le-Vieux Cedex, France
                   (UMR 5814 du CNRS-IN2P3 associ\'ee \`a
                   l'Universit\'e de Savoie),
                {e-mail: kaufhold@lapp.in2p3.fr}} \\[0.2cm]
{\small \em $^{h}$Humboldt-Universit\"at zu Berlin,
                   Institut f\"ur Physik,
                   Newtonstr. 15,
                   D-12489 Berlin, Germany,
                {e-mail: lacker@physik.hu-berlin.de}}\\[0.2cm]
{\small \em $^{i}$Laboratoire de Physique Corpusculaire de Clermont-Ferrand,
                  Universit\'e Blaise Pascal,
                  24 Avenue des Landais F-63177 Aubiere Cedex,
		  (UMR 6533 du CNRS-IN2P3 associ\'ee \`a
                   l'Universit\'e Blaise Pascal),
		  {e-mail: monteil@clermont.in2p3.fr, niess@clermont.in2p3.fr}}

 \newpage\thispagestyle{plain} 
  {\centerline{\textbf{\Large Abstract}}
  \vskip 2em
    \noindent
  We analyse 
  three different New Physics scenarios for 
  $\Delta F=2$ flavour-changing neutral currents in the quark sector in the light
  of recent data on neutral-meson mixing. 
  We parametrise generic New Physics contributions to  
  \bbmq, $q\!=\!d,s$, in terms of one complex 
  quantity $\Delta_q$, while three parameters $\Delta_K^{tt}$,
  $\Delta_K^{ct}$ and
  $\Delta_K^{cc}$ are needed to describe \kkm.  
  In Scenario I, we consider uncorrelated 
  New Physics contributions in the $B_{d}$, $B_{s}$, and $K$ sectors. 
  In this scenario, it is only possible to constrain 
  the parameters $\Delta_d$ and $\Delta_s$ whereas there are no non-trivial
  constraints on the kaon parameters.
  In Scenario II, we study the case of 
  Minimal Flavour Violation (MFV)
  and  
  small bottom Yukawa coupling, where
  $\Delta\equiv\Delta_d=\Delta_s=\Delta_K^{tt}$. We show that
  $\Delta$ must then be real, so that no new CP phases can be accomodated,
  and express the remaining parameters $\Delta_K^{cc}$ and $\Delta_K^{ct}$
  in terms of $\Delta$ in this scenario.
%  In addition, 
%  $\Delta_K^{cc}$ is very close to the Standard Model value 
%  $\Delta_K^{cc}=1$ and $\Delta_K^{ct}$ 
%  can be approximately expressed in terms of $\Delta_K^{tt}$.  
  Scenario III is the generic MFV case with
  large bottom Yukawa couplings. 
  In this case, the Kaon sector is uncorrelated to the $B_d$ and 
  $B_s$ sectors.  As in the second scenario 
  one has $\Delta_d=\Delta_s\equiv\Delta$, however, 
  now with a complex parameter $\Delta$. 
  Our quantitative analyses consist of global CKM fits within the Rfit frequentist statistical approach, 
  determining the Standard Model parameters and the
  new physics parameters of the studied scenarios simultaneously. 
We find that the recent
measurements indicating discrepancies with the Standard Model are well
accomodated in Scenarios I and III with new mixing phases, 
with a slight preference for Scenario I
%However, Scenario III
%is slightly disfavoured with respect to the first one 
that permits 
different new CP phases in the $B_d$ and $B_s$ systems. 
Within our statistical framework, we find that 
the Standard-Model hypothesis $\Delta_d=\Delta_s=1$ is disfavoured 
with p-values of $3.4\sigma$ and $3.1\sigma$ in Scenarios I and III respectively.} 
    

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