Physics Letters B 801 (2020) 135187
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Gluonic probe for the short range correlation in nucleus
Ji Xu
a,b,∗
, Feng Yuan
b,∗
a
Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
b
Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
a r t i c l e i n f o a b s t r a c t
Article history:
Received
7 October 2019
Received
in revised form 21 November 2019
Accepted
23 December 2019
Available
online 31 December 2019
Editor:
J. Hisano
We investigate the gluonic probe to the nucleon-nucleon short range correlation (SRC) in nucleus
through heavy flavor production in deep inelastic scattering (DIS). The relevant EMC effects of F
c
¯
c
2
structure function will provide a universality test of the SRCs which have been extensively studied in
the quark-channel. These SRCs can also be studied through the sub-threshold production of heavy flavor
in eA collisions at the intermediate energy electron-ion collider, including open Charm and J/ψ (ϒ)
production.
© 2019 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
There have been renaissance interests to investigate the short-
range
nucleon-nucleon correlation (SRC) of nucleus in recent
years [1–7]. The SRC describes the probability that the two nucle-
ons
are close in coordinate space, as a result of nontrivial nucleon-
nucleon
interactions in nucleus. Especially, the experiment efforts
made at JLab have stimulated much of the research activities in
the field. The connection between the SRC and the well-known
EMC effects in nuclear structure function measurements have been
extensively investigated with compelling evidences [8–18]. Since
the EMC effects concerns the parton distribution functions through
short distance physics while the SRC represents the wave function
information of nucleons inside the nucleus, this relation, if finally
established rigorously, shall provide a unique method to study nu-
clear
structure physics and help to answer the long standing quest
to explore nuclear structure through the first principle of strong
interaction QCD theory, see, for example, some of recent develop-
ments
in Refs. [19–21].
One
of the key aspects of the connection between the SRC and
EMC effects is the universality, where the partonic structure from
the correlated nucleon-nucleon in the nucleus contribute to both
phenomena [18–24]. Therefore, to fully establish the physics case
of the connection, we need to build a rigorous test on the uni-
versality.
In this paper, we propose a number of novel observables
for this purpose, focusing on the gluonic channel. We will tackle
this issue from two fronts, both through heavy flavor production.
*
Corresponding authors.
E-mail
address: fyuan@lbl.gov (F. Yuan).
First, we will discuss the nuclear modification of the gluon dis-
tribution
function in the EMC region. Heavy flavor production in
DIS is sensitive to the gluon distribution, and the nuclear modi-
fication
will provide crucial information on the gluon distribution
in nucleus. This can be studied by measuring the charm-structure
function: F
c
¯
c
2
and F
c
¯
c
L
. We will demonstrate the sensitivities for
an intermediate energy EIC (IEEIC), where the main kinematic fo-
cuses
are in the EMC region, i.e., 0.3 < x < 0.7[25]. Meanwhile,
the nuclear modification for the gluon distribution has been a sub-
ject
for decades’ study, and has been widely applied in high energy
processes [26–31]. The measurements at the future IEEIC and the
EIC [32–34]will provide an important contribution to constrain the
gluon distribution in nucleus.
Second,
we propose to study the SRC through the sub-threshold
heavy flavor production. This can be done by measuring either
open Charm or Charmonium production in eA collisions below
the ep threshold. This is similar to the structure function measure-
ments
beyond x
B
∼ 1.
Together
with the quark sector study, the gluonic probe pro-
vides
an important test of the universality of the SRC. In addition,
because of the isospin symmetry, the nuclear modification can be
derived directly without considering the isospin dependence as
that for the quark sector. This shall provide a crucial way to disen-
tangle
different methods, for example, to extract the nuclear EMC
effects [35,36].
The
rest of this paper is organized as follows. We first study
the charm structure function and the nuclear effects in the EMC
region. We apply the EPPS16 parameterization for the gold nu-
cleus
and demonstrate the sensitivity to study the EMC effects
in the gluonic channel. To illustrate the universality feature, we
https://doi.org/10.1016/j.physletb.2019.135187
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© 2019 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
.