强子对撞机上的强光子与强夸克对产生的电弱校正
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Physics Letters B 766 (2017) 102–106
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Electroweak corrections to top quark pair production in association
with a hard photon at hadron colliders
Peng-Fei Duan
a
, Yu Zhang
b,a,∗
, Yong Wang
c
, Mao Song
d
, Gang Li
d
a
City College, Kunming University of Science and Technology, Kunming, Yunnan 650051, China
b
School of Physics, Nanjing University, Nanjing, Jiangsu 210093, China
c
Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
d
School of Physics and Material Science, Anhui University, Hefei, Anhui 230039, China
a r t i c l e i n f o a b s t r a c t
Article history:
Received
1 December 2016
Accepted
31 December 2016
Available
online 5 January 2017
Editor:
J. Hisano
We present the next-to-leading order (NLO) electroweak (EW) corrections to the top quark pair produc-
tion
associated with a hard photon at the current and future hadron colliders. The dependence of the
leading order (LO) and NLO EW corrected cross sections on the photon transverse momentum cut are in-
vestigated.
We also provide the LO and NLO EW corrected distributions of the transverse momentum of
final top quark and photon and the invariant mass of top quark pair and top–antitop-photon system. The
results show that the NLO EW corrections are significant in high energy regions due to the EW Sudakov
effect.
© 2017 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
In the standard model (SM), the top quark is a very special
particle. Because its mass is much larger than any other SM ele-
mentary
particles (except Higgs boson), the top quark is speculated
to play a special role in electroweak symmetry breaking (EWSB).
Since its unique properties have long been believed of potentially
carrying important information to solve some of the paramount
open questions in particle physics, precise measurements of the
cross sections and properties of top quark production channels are
significant. With the measurement of the cross section of top quark
pair production in association with a hard photon, the strength of
the electromagnetic coupling of the top quark and photon can be
probed directly.
Experimentally, measurements of the production rate of t
¯
tγ
have been performed in p
¯
p collisions at the Tevatron by the CDF
Collaboration at
√
s = 1.96 TeV [1] and in pp collisions at the LHC
by the ATLAS Collaboration at
√
s = 7TeV [2] and by the CMS Col-
laboration
at
√
s = 8TeV [3]. From the theoretical point of view,
the calculation of the cross section of t
¯
tγ production at hadron
colliders beyond the leading order (LO) used to be a very chal-
lenging
problem. The calculation of NLO QCD corrections to the
*
Corresponding author.
E-mail
address: dayu@nju.edu.cn (Y. Zhang).
production of t
¯
t pair and a hard photon at the Tevatron and the
LHC have been performed in Refs. [4–6], which has a strong phe-
nomenological
motivation due to the large K -factor.
With
both the energy and luminosity increment in Run II of
the LHC compared with Run I and future hadron colliders whose
energy can be up to 100 TeV [7,8] planed to be built, the need
to increase the precision of the perturbative predictions becomes
important and urgent. At fixed order, there are two ways [9,10]:
computing either the next-to-next-to-leading order (NNLO) QCD
or the NLO electroweak (EW) corrections, which are believed to
be comparable numerically. Although the NLO EW correction is
normally suppressed by the smallness of the coupling constant
α and nominally subdominant with respect to the QCD contri-
butions,
the NLO EW correction can become significant in the
high-energy domain due to the appearance of Sudakov logarithms
[11–13] that result from the virtual exchange of soft or collinear
massive weak gauge boson. In this paper, we aim at the NLO
EW corrections for the t
¯
tγ production at the LHC and at future
higher energy hadron colliders and present the results for the first
time.
The
rest of the paper is organized as follows: In section 2, we
provide a general setup of our calculation. In section 3, we present
the numerical results and discussions for the LO and NLO EW cor-
rected
integrated and differential cross sections. Finally, a short
summary is given in section 4.
http://dx.doi.org/10.1016/j.physletb.2016.12.061
0370-2693/
© 2017 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.
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