A Mathematica based Version of the CKMfitter Package

Chapter 6
New Physics Beyond the
Standard Model
The Standard Model describes successfully all the present data from flavor physics
experiments. Nevertheless, there are still many reasons to believe in physics beyond
the SM. For example, evidences for unobserved “dark matter” and “dark energy”
from cosmic microwave background radiation measurements are not described by
the SM. Furthermore, the strength of CP violation in the CKM matrix, expressed
through the Jarlskog invariant, is significantly to weak and the electroweak phase
transition is not intens enough to generate the observed baryon asymmetry in the
universe.
In the following, two extensions of the Standard Model are discussed. First of all a
model independent description of NP contributions to B 0 - ¯ B 0 mixing and secondly,
charged Higgs contributions to the leptonic decay width of charged B mesons in
Two Higgs Doublet Models (2HDM).
6.1 New Physics in B 0 - ¯B 0 Oscillations
B 0 - ¯ B 0 oscillation occurs in the SM through |∆B| = 2 transitions. A model independent
description of New Physics contributions introduces two additional parameters,
the relative amplitude r 2 d and the relative phase 2ϑd between the mixing
matrix elements including SM and NP contributions compared to SM contributions
only [65, 66]:
� B 0 � �H SM+NP � � ¯ B 0 �
� B 0 |H SM | ¯ B 0 � = r2 d ei2ϑd . (6.1)
The Standard Model is referred to as r 2 d = 1 and 2ϑd = 0. Additional assumptions
are a unitary 3 × 3 CKM matrix and no NP contributions to tree level dominated
processes (which means Γ12 = ΓSM 12 ). More specifically, decay transitions with four
flavor changes (i.e. b → q1¯q2q3, q1 �= q2 �= q3) are dominated by the SM [4]. The
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