Top Yukawa coupling measurement at the muon collider
Miranda Chen, Da Liu
Abstract
We have presented a detailed study about the prospects for the measurement of the top Yukawa coupling in the vector boson fusion production of a top quark pair at high energy muon colliders. By employing the effective <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>W</a:mi></a:math> approximation and the high energy limit for the helicity amplitudes of the subprocess <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msup><c:mi>W</c:mi><c:mo>+</c:mo></c:msup><c:msup><c:mi>W</c:mi><c:mo>−</c:mo></c:msup><c:mo stretchy="false">→</c:mo><c:mi>t</c:mi><c:mover accent="true"><c:mi>t</c:mi><c:mo stretchy="false">¯</c:mo></c:mover></c:math>, we have derived the energy scaling of the statistical signal significance in the presence of the anomalous couplings by focusing on the interference term only. The sensitivity on the top Yukawa coupling decreases as the bin energy increases. For the anomalous triple gauge boson couplings and the gauge-boson-fermion couplings with <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:msup><h:mi>E</h:mi><h:mn>2</h:mn></h:msup></h:math> energy growing behavior, the signal significance has mild increase at the beginning and starts to decrease for <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:msub><j:mover accent="true"><j:mi>s</j:mi><j:mo stretchy="false">^</j:mo></j:mover><j:mrow><j:mi>t</j:mi><j:mover accent="true"><j:mi>t</j:mi><j:mo stretchy="false">¯</j:mo></j:mover></j:mrow></j:msub><j:mo>∼</j:mo><j:mn>0.2</j:mn><j:msub><j:mi>s</j:mi><j:mrow><j:msup><j:mi>μ</j:mi><j:mo>+</j:mo></j:msup><j:msup><j:mi>μ</j:mi><j:mo>−</j:mo></j:msup></j:mrow></j:msub></j:math>. The 95% CL on the anomalous top Yukawa coupling is projected to be 5.6% (1.7%) at a 10 (30) TeV muon collider, which is comparable to the sensitivity of 2% at the 100 TeV collider. Published by the American Physical Society 2024