Amplitude analysis of B0→KS0K+K− decays in a quasi-two-body QCD factorization approach

The <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>B</a:mi><a:mn>0</a:mn></a:msup><a:mo stretchy="false">→</a:mo><a:msubsup><a:mi>K</a:mi><a:mi>S</a:mi><a:mn>0</a:mn></a:msubsup><a:msup><a:mi>K</a:mi><a:mo>+</a:mo></a:msup><a:msup><a:mi>K</a:mi><a:mo>−</a:mo></a:msup></a:math> decay amplitude is derived within a quasi-two-body QCD factorization framework in terms of kaon form factors and <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:msup><d:mi>B</d:mi><d:mn>0</d:mn></d:msup></d:math> to two-kaon-transition functions. The final state kaon-kaon interactions in the <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mi>S</f:mi></f:math>, <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mi>P</h:mi></h:math>, and <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:mi>D</j:mi></j:math> waves are taken into account. The unitarity constraints are satisfied for the two kaons in scalar states. It is shown that with few terms of the full decay amplitude one may reach a fair agreement with the total branching fraction and Dalitz-plot projections published in 2010 by the Belle Collaboration and in 2012 by the Collaboration. With 13 free parameters, our model fits the corresponding 422 data with a <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:msup><l:mi>χ</l:mi><l:mn>2</l:mn></l:msup></l:math> of 583.6 which leads to a <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"><n:msup><n:mi>χ</n:mi><n:mn>2</n:mn></n:msup></n:math> per degree of freedom equal to 1.43. The dominant branching fraction arises from the <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline"><p:msub><p:mi>f</p:mi><p:mn>0</p:mn></p:msub><p:mo stretchy="false">(</p:mo><p:msup><p:mi>K</p:mi><p:mo>+</p:mo></p:msup><p:msup><p:mi>K</p:mi><p:mo>−</p:mo></p:msup><p:mo stretchy="false">)</p:mo><p:msubsup><p:mi>K</p:mi><p:mi>S</p:mi><p:mn>0</p:mn></p:msubsup></p:math> mode with 83.0% of the total branching. The next important mode is dominated by <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mi>ϕ</t:mi><t:msubsup><t:mi>K</t:mi><t:mi>S</t:mi><t:mn>0</t:mn></t:msubsup></t:math> plus small <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:mi>ω</v:mi><v:msubsup><v:mi>K</v:mi><v:mi>S</v:mi><v:mn>0</v:mn></v:msubsup></v:math> and <x:math xmlns:x="http://www.w3.org/1998/Math/MathML" display="inline"><x:msup><x:mi>ρ</x:mi><x:mn>0</x:mn></x:msup><x:msubsup><x:mi>K</x:mi><x:mi>S</x:mi><x:mn>0</x:mn></x:msubsup></x:math> modes with 18.3% of the total. Then follows the <z:math xmlns:z="http://www.w3.org/1998/Math/MathML" display="inline"><z:msubsup><z:mi>a</z:mi><z:mn>0</z:mn><z:mo>±</z:mo></z:msubsup><z:msup><z:mi>K</z:mi><z:mo>∓</z:mo></z:msup></z:math> mode with 6.2%. Adding the other smaller modes, the total percentage sum is 107.7% which indicates a small interference contribution. In most regions of the Dalitz plot, our model gives rather small <bb:math xmlns:bb="http://www.w3.org/1998/Math/MathML" display="inline"><bb:mi>C</bb:mi><bb:mi>P</bb:mi></bb:math> asymmetry, but in some parts its values can be large and positive or negative. Its predicted total value is equal to <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:mo>−</db:mo><db:mn>0.11</db:mn><db:mo>%</db:mo></db:math>. The calculated time dependent <fb:math xmlns:fb="http://www.w3.org/1998/Math/MathML" display="inline"><fb:mrow><fb:mi>C</fb:mi><fb:mi>P</fb:mi></fb:mrow></fb:math>-asymmetry parameters agree, within errors, with those obtained by the analysis. Our model amplitude can be the basis for a parametrization in experimental Dalitz plot analyses of LHCb and Belle II Collaborations.