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A Mathematica based Version of the CKMfitter Package

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44 Chapter 5. Probing <strong>the</strong> Standard Model<br />

In addition to <strong>the</strong> Standard Global CKM Fit, several fits for different classes <strong>of</strong><br />

constraints have been performed in this <strong>the</strong>sis. Each plot <strong>of</strong> Figure 5.8 shows <strong>the</strong><br />

95 % CL belts for <strong>the</strong> individual constraints and <strong>the</strong> allowed area from <strong>the</strong> combined<br />

fits.<br />

In <strong>the</strong> first row, <strong>the</strong> fit results, obtained from <strong>the</strong> CP-violating observables α, sin 2β,<br />

γ and |ɛK| are compared with those obtained from <strong>the</strong> CP-conserving constraints<br />

|Vub|, ∆md and ∆md & ∆ms. An important observation is that a non-real CKM<br />

matrix with ¯η �= 0 and thus CP violation is also obtained from CP-conserving constraints.<br />

The crucial input in this constraint is <strong>the</strong> recent measurement <strong>of</strong> ∆ms by<br />

CDF, presented at <strong>the</strong> winter conferences 2006.<br />

The second row shows <strong>the</strong> impact <strong>of</strong> <strong>the</strong>oretical uncertainties. The allowed area from<br />

<strong>the</strong> fit using only <strong>the</strong> UT angle constraints α, sin 2β and γ is much smaller than <strong>the</strong><br />

area obtained from <strong>the</strong> constraints |Vub|, |ɛK|, ∆md and ∆md & ∆ms which depend<br />

on additional QCD parameters.<br />

The left figure <strong>of</strong> <strong>the</strong> third row shows <strong>the</strong> fit results from constraints which are<br />

dominated by tree-level contributions. Beside |Vub|, a combined constraint from α<br />

and β is used which allows to extract γ. Assuming no New Physics contributions to<br />

<strong>the</strong> ∆I = 3/2 part <strong>of</strong> b → d transitions in <strong>the</strong> extraction <strong>of</strong> α leads in combination<br />

with β, measured in tree-level B → Mc¯c transitions, to a cancellation <strong>of</strong> a possible<br />

New Physics mixing phase ϑd (see Chapter 6). That gives a determination <strong>of</strong><br />

γ = π − β − α independent from possible New Physics in B 0 - ¯ B 0 mixing. Compared<br />

to that, <strong>the</strong> right plot shows constraints from <strong>the</strong> loop-dominated observables sin 2β,<br />

|ɛK|, ∆md and ∆md & ∆ms.<br />

Since all fits are consistent with <strong>the</strong> Standard Global CKM Fit and <strong>the</strong> allowed<br />

(¯ρ,¯η) range is quite small, <strong>the</strong> space for possible New Physics effects is significantly<br />

constrained. A more detailed discussion <strong>of</strong> possible NP contributions in B 0 - ¯ B 0<br />

mixing is described in <strong>the</strong> next chapter.

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