Abstract
In this letter, we evaluate the potential of linear e+e− colliders to measure the top quark mass in radiative events and in a suitable short-distance scheme. We present a calculation of the differential cross section for production of a top quark pair in association with an energetic photon from initial state radiation, as a function of the invariant mass of the tt¯ system. This matched calculation includes the QCD enhancement of the cross section around the tt¯ production threshold and remains valid in the continuum well above the threshold. The uncertainty in the top mass determination is evaluated in realistic operating scenarios for the Compact Linear Collider (CLIC) and the International Linear Collider (ILC), including the statistical uncertainty and the theoretical and experimental systematic uncertainties. With this method, the top quark mass can be determined with a precision of 110 MeV in the initial stage of CLIC, with 1 ab−1 at s=380 GeV, and with a precision of approximately 150 MeV at the ILC, with L=4 ab−1 at s=500 GeV. Radiative events allow measurements of the top quark mass at different renormalization scales, and we demonstrate that such a measurement can yield a statistically significant test of the evolution of the MSR mass mtMSR(R) for scales R<mt.
Highlights
The top quark plays an important role in the Standard Model (SM) and in many of its extensions
We study the potential for a top quark mass measurement in two concrete scenarios, the Compact Linear Collider (CLIC) [19,20] initial-stage run colliding at a center-of-mass energy of 380 GeV and the International Linear Collider (ILC) [21,22] run at 500 GeV
Examples of pseudo-experiments are shown in Fig. 4 for CLIC and the ILC
Summary
The top quark plays an important role in the Standard Model (SM) and in many of its extensions. Boronat et al / Physics Letters B 804 (2020) 135353 duces the invariant mass available for top-antitop pair production, and the spectrum develops a strong dependence on the top quark mass, as the invariant mass of the ttpair approaches the strong interaction production threshold Such a measurement can be performed in continuum ttγ production at any center-of-mass energy above the ttproduction threshold and does not require a dedicated ttthreshold run of the experiment. The method offers a rigorous interpretation of the extracted top quark mass in terms of short-distance renormalization schemes, as the differential cross section can be calculated with high precision and the measurement is inclusive in the top quark decay products. We study the impact of the luminosity spectrum on this measurement in detail
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