Maximizing the physics potential of B±→π±μ+μ</mml:…

We present a method that maximizes the experimental sensitivity to new physics contributions in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>B</a:mi><a:mo>±</a:mo></a:msup><a:mo stretchy="false">→</a:mo><a:mrow><a:msup><a:mi>π</a:mi><a:mo>±</a:mo></a:msup><a:msup><a:mi>μ</a:mi><a:mo>+</a:mo></a:msup><a:msup><a:mi>μ</a:mi><a:mo>−</a:mo></a:msup></a:mrow></a:math> decays. This method relies on performing an unbinned maximum likelihood fit to both the measured dimuon <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:msup><d:mi>q</d:mi><d:mn>2</d:mn></d:msup></d:math> distribution of <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:msup><f:mi>B</f:mi><f:mo>±</f:mo></f:msup><f:mo stretchy="false">→</f:mo><f:mrow><f:msup><f:mi>π</f:mi><f:mo>±</f:mo></f:msup><f:msup><f:mi>μ</f:mi><f:mo>+</f:mo></f:msup><f:msup><f:mi>μ</f:mi><f:mo>−</f:mo></f:msup></f:mrow></f:math> decays, and theory calculations at spacelike <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msup><i:mi>q</i:mi><i:mn>2</i:mn></i:msup></i:math>, where QCD predictions are most reliable. Using known properties of the decay amplitude we employ a dispersion relation to describe the nonlocal hadronic contributions across spacelike and timelike <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:msup><k:mi>q</k:mi><k:mn>2</k:mn></k:msup></k:math> regions. The fit stability and the sensitivity to new physics couplings and new sources of <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>C</m:mi><m:mi>P</m:mi></m:math>-violation are studied for current and future data-taking scenarios, with the LHCb experiment as an example. The proposed method offers a precise and reliable way to search for new physics in these decays.