Measurement of the CKM angle γ and $$ {B}_s^0\hbox{-} {\overline{B}}_s^0 $$ mixing frequency with $$ {B}_s^0\to {D}_s^{\mp }{h}^{\pm }{\pi}^{\pm }{\pi}^{\mp } $$ decays



Aaij, R, Abellán Beteta, C, Ackernley, T, Adeva, B, Adinolfi, M, Afsharnia, H, Aidala, CA, Aiola, S, Ajaltouni, Z, Akar, S
et al (show 963 more authors) (2021) Measurement of the CKM angle γ and $$ {B}_s^0\hbox{-} {\overline{B}}_s^0 $$ mixing frequency with $$ {B}_s^0\to {D}_s^{\mp }{h}^{\pm }{\pi}^{\pm }{\pi}^{\mp } $$ decays. Journal of High Energy Physics, 2021 (3).

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Abstract

<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>The CKM angle <jats:italic>γ</jats:italic> is measured for the first time from mixing-induced <jats:italic>CP</jats:italic> violation between <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {B}_s^0\to {D}_s^{\mp }{K}^{\pm }{\pi}^{\pm }{\pi}^{\mp } $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> <mml:mo>→</mml:mo> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>∓</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>±</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>±</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>∓</mml:mo> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula> and <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {\overline{B}}_s^0\to {D}_s^{\pm }{K}^{\mp }{\pi}^{\mp }{\pi}^{\pm } $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mover> <mml:mi>B</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>s</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> <mml:mo>→</mml:mo> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>±</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>∓</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>∓</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>±</mml:mo> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula> decays reconstructed in proton-proton collision data corresponding to an integrated luminosity of 9 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> recorded with the LHCb detector. A time-dependent amplitude analysis is performed to extract the <jats:italic>CP</jats:italic>-violating weak phase <jats:italic>γ</jats:italic> − 2<jats:italic>β</jats:italic><jats:sub><jats:italic>s</jats:italic></jats:sub> and, subsequently, <jats:italic>γ</jats:italic> by taking the <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {B}_s^0\hbox{-} {\overline{B}}_s^0 $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> <mml:mo>‐</mml:mo> <mml:msubsup> <mml:mover> <mml:mi>B</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>s</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math></jats:alternatives></jats:inline-formula> mixing phase <jats:italic>β</jats:italic><jats:sub><jats:italic>s</jats:italic></jats:sub> as an external input. The measurement yields <jats:italic>γ</jats:italic> = (44 ± 12)° modulo 180°, where statistical and systematic uncertainties are combined. An alternative model-independent measurement, integrating over the five-dimensional phase space of the decay, yields <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \gamma =\left({44}_{-13}^{+20}\right){}^{\circ} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>γ</mml:mi> <mml:mo>=</mml:mo> <mml:mfenced> <mml:msubsup> <mml:mn>44</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>13</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>20</mml:mn> </mml:mrow> </mml:msubsup> </mml:mfenced> <mml:mo>°</mml:mo> </mml:math></jats:alternatives></jats:inline-formula> modulo 180°. Moreover, the <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {B}_s^0\hbox{-} {\overline{B}}_s^0 $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> <mml:mo>‐</mml:mo> <mml:msubsup> <mml:mover> <mml:mi>B</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>s</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math></jats:alternatives></jats:inline-formula> oscillation frequency is measured from the flavour-specific control channel <jats:inline-formula><jats:alternatives><jats:tex-math>$$ {B}_s^0\to {D}_s^{-}{\pi}^{+}{\pi}^{+}{\pi}^{-} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> <mml:mo>→</mml:mo> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>−</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>−</mml:mo> </mml:msup> </mml:math></jats:alternatives></jats:inline-formula> to be ∆<jats:italic>m</jats:italic><jats:sub><jats:italic>s</jats:italic></jats:sub> = (17<jats:italic>.</jats:italic>757 ± 0<jats:italic>.</jats:italic>007(stat) ± 0<jats:italic>.</jats:italic>008(syst)) ps<jats:sup><jats:italic>−</jats:italic>1</jats:sup>, consistent with and more precise than the current world-average value.</jats:p>

Item Type: Article
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 21 Apr 2021 10:27
Last Modified: 02 Dec 2021 08:18
DOI: 10.1007/jhep03(2021)137
Open Access URL: https://link.springer.com/content/pdf/10.1007/JHEP...
URI: https://livrepository.liverpool.ac.uk/id/eprint/3120044