CP violation and determination of the $bs$ "flat" unitarity triangle at FCCee

We investigate the sensitivity with which two angles of the flat unitarity triangle, defined by <math display="inline"><msubsup><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>u</mi><mi>s</mi></mrow></msub><mo>+</mo><msubsup><mi>V</mi><mrow><mi>c</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>c</mi><mi>s</mi></mrow></msub><mo>+</mo><msubsup><mi>V</mi><mrow><mi>t</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>t</mi><mi>s</mi></mrow></msub><mo>=</mo><mn>0</mn></math>, can possibly be measured directly at FCC-ee. We show that the measured errors on the angle <math display="inline"><msub><mi>α</mi><mi>s</mi></msub><mo>=</mo><mi>arg</mi><mo stretchy="false">(</mo><mo>-</mo><msubsup><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>u</mi><mi>s</mi></mrow></msub><mo stretchy="false">/</mo><msubsup><mi>V</mi><mrow><mi>t</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>t</mi><mi>s</mi></mrow></msub><mo stretchy="false">)</mo></math> and <math display="inline"><msub><mi>β</mi><mi>s</mi></msub><mo>=</mo><mi>arg</mi><mo stretchy="false">(</mo><mo>-</mo><msubsup><mi>V</mi><mrow><mi>t</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>t</mi><mi>s</mi></mrow></msub><mo stretchy="false">/</mo><msubsup><mi>V</mi><mrow><mi>c</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>c</mi><mi>s</mi></mrow></msub><mo stretchy="false">)</mo></math> should be better than 0.4° and 0.035°, respectively. These measurements, combined with the measurement of the third angle <math display="inline"><msub><mi>γ</mi><mi>s</mi></msub><mo>=</mo><mi>arg</mi><mo stretchy="false">(</mo><mo>-</mo><msubsup><mi>V</mi><mrow><mi>c</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>c</mi><mi>s</mi></mrow></msub><mo stretchy="false">/</mo><msubsup><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow><mo>*</mo></msubsup><msub><mi>V</mi><mrow><mi>u</mi><mi>s</mi></mrow></msub><mo stretchy="false">)</mo></math>, discussed in a different paper, will contribute to probing the consistency of the <math display="inline"><mi>C</mi><mi>P</mi></math> sector of the Standard Model further with an unprecedented level of accuracy.