Full electroweak radiative corrections to with GRACE-Loop

P. H. Khiem; J. Fujimoto; T. Ishikawa; T. Kaneko; K. Kato; Y. Kurihara; Y. Shimizu; T. Ueda; J. A. M. Vermaseren; Y. Yasui

doi:10.1140/epjc/s10052-013-2400-3

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Particles and Fields

Eur. Phys. J. C (2013) 73: 2400
https://doi.org/10.1140/epjc/s10052-013-2400-3

Regular Article - Theoretical Physics

Full $\mathcal{O}(\alpha)$ electroweak radiative corrections to $e^{+}e^{-} \rightarrow t \bar{t} \gamma$ with GRACE-Loop

P. H. Khiem¹^,2^*, J. Fujimoto¹, T. Ishikawa¹, T. Kaneko¹, K. Kato³, Y. Kurihara¹, Y. Shimizu¹, T. Ueda⁴, J. A. M. Vermaseren⁵ and Y. Yasui⁶

¹ KEK, Oho 1-1, Tsukuba, Ibaraki, 305-0801, Japan
² SOKENDAI University, Shonan Village, Hayama, Kanagawa, 240-0193, Japan
³ Kogakuin University, Shinjuku, Tokyo, 163-8677, Japan
⁴ Karlsruhe Institute of Technology (KIT), 76128, Karlsruhe, Germany
⁵ NIKHEF, Science Park 105, 1098 XG, Amsterdam, The Netherlands
⁶ Tokyo Management College, Ichikawa, Chiba, 272-0001, Japan

^* e-mail: khiemph@post.kek.jp

Received: 4 February 2013
Revised: 31 March 2013
Published online: 20 April 2013

Abstract

We present the full $\mathcal{O}(\alpha)$ electroweak radiative corrections to the process $e^{+}e^{-} \rightarrow t \bar{t} \gamma$ at the International Linear Collider (ILC). The computation is performed with the help of the GRACE-Loop system. We present the total cross-section and the top quark forward–backward asymmetry (A _FB) as a function of the center-of-mass energy and compare them with the process $e^{+}e^{-} \rightarrow t \bar{t}$ . We find that the value of A _FB in $t \bar{t} \gamma$ production is larger than A _FB in $t\bar{t}$ production. It is an important result for the measurement of the top quark forward–backward asymmetry at the ILC. Applying a structure function method, we also subtract the QED correction to gain the genuine weak correction in both the α scheme and the G _μ scheme ( $\delta_{W}^{G_{\mu}}$ ). We obtain numerical values for $\delta_{W}^{G_{\mu}}$ which are changing from 2 % to −24 % when we vary the center-of-mass energy from 360 GeV to 1 TeV.