Physics Letters B 781 (2018) 601–606
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Magnetic moments of the lowest-lying singly heavy baryons
Ghil-Seok Yang
a
, Hyun-Chul Kim
b,c,d,∗
a
Department of Physics, Soongsil University, Seoul 06978, Republic of Korea
b
Department of Physics, Inha University, Incheon 22212, Republic of Korea
c
Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047, Japan
d
School of Physics, Korea Institute for Advanced Study (KIAS), Seoul 02455, Republic of Korea
a r t i c l e i n f o a b s t r a c t
Article history:
Received
15 February 2018
Received
in revised form 19 March 2018
Accepted
23 April 2018
Available
online 25 April 2018
Editor:
J.-P. Blaizot
Keywords:
Heavy
baryons
Pion
mean fields
Chiral
quark-soliton model
Magnetic
moments
A light baryon is viewed as N
c
valence quarks bound by meson mean fields in the large N
c
limit. In much
the same way a singly heavy baryon is regarded as N
c
−1valence quarks bound by the same mean fields,
which makes it possible to use the properties of light baryons to investigate those of the heavy baryons.
A heavy quark being regarded as a static color source in the limit of the infinitely heavy quark mass,
the magnetic moments of the heavy baryon are determined entirely by the chiral soliton consisting of a
light-quark pair. The magnetic moments of the baryon sextet are obtained by using the parameters fixed
in the light-baryon sector. In this mean-field approach, the numerical results of the magnetic moments
of the baryon sextet with spin 3/2are just 3/2 larger than those with spin 1/2. The magnetic moments
of the bottom baryons are the same as those of the corresponding charmed baryons.
© 2018 The Authors. 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
Very recently, Ref. [1]showed that when the number of col-
ors
(N
c
) goes to infinity singly heavy baryons can be described
as N
c
− 1valence quarks bound by the meson mean fields that
also have portrayed light baryons as N
c
valence quarks bound by
the same mean fields [2,3], being motivated by Diakonov [4]. The
masses of the lowest-lying singly heavy baryons were well repro-
duced
in both the charmed and bottom sectors, and the mass of
the
b
was predicted within this framework. Using the method
developed in Ref. [1], we were able to interpret two narrow
c
resonances as exotic baryons belonging to the anti-decapentaplet
(15)[5]among five
c
s found by the LHCb Collaboration [6].
This mean-field approach is called the chiral quark-soliton model
(χ QSM) [7](for a review, see Refs. [8,9] and references therein).
Very recently, the model has also described successfully strong de-
cays
of heavy baryons [10] including those of the newly found two
narrow
c
s.
The magnetic moments of the heavy baryons have been al-
ready
investigated within various different approaches such as
quark models [11–13], the MIT bag model [14], the quark potential
model [15,16], the Skyrme models in bound-state approaches [17,
18],
a relativistic quark model [19], lattice QCD [20–22], heavy-
*
Corresponding author.
E-mail
addresses: ghsyang @ssu .ac .kr (G.-S. Yang), hchkim @inha .ac .kr (H.-C. Kim).
baryon chiral perturbation theories [23,24], and QCD sum rules [25,
26],
and so on. Since there are no experimental data available yet,
it is of great interest to compare the results with those from sev-
eral
different approaches. Since the baryon anti-triplet (3) consists
of the light-quark pair with the total light-quark spin J = 0, the
corresponding magnetic moment vanishes in the present mean-
field
approach with the infinitely heavy-quark mass limit consid-
ered.
Thus, in the present work, we want to employ the χ QSM
to compute the magnetic moments of the lowest-lying singly
heavy baryons, in particular, the baryon sextet (6) with both spin
J
=1/2 and J
=3/2. The magnetic moments of the light baryons
were already studied within the χ QSM [27,28]. A merit of this
approach is that we can deal with light and heavy baryons on
the same footing. All the dynamical parameters required for the
present analysis were determined in Ref. [29]based on the ex-
perimental
data on the magnetic moments of the baryon octet,
we have no additional free parameter to handle for those of the
heavy baryons. We obtain the results for the magnetic moments
of the baryon sextet and compare them with those from other
models and lattice QCD. The results turn out to be consistent
with those from the other works, in particular, with those from
Ref. [19]. Compared with the results from the lattice QCD [20–22],
the present ones are consistently larger than them except for the
++
c
magnetic moment.
The structure of the present work is sketched as follows: In
Section 2, we briefly review the general formalism of the χ QSM in
https://doi.org/10.1016/j.physletb.2018.04.042
0370-2693/
© 2018 The Authors. 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
.