Mass spectrum of the hidden-charm pentaquarks in the compact diquark model

• Published in: The journal of high energy physics Vol. 2019; no. 10; pp. 1 - 57
• Main Authors: Ali, Ahmed, Ahmed, Ishtiaq, Aslam, M. Jamil, Parkhomenko, Alexander Ya, Rehman, Abdur
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-10-2019; Springer Nature B.V; SpringerOpen
• Subjects: Baryons; Charm (particle physics); Classical and Quantum Gravitation; Decay; Elementary Particles; Flavor (particle physics); Hadrons; High energy physics; Phenomenological Models; Physics; Physics and Astronomy; QCD Phenomenology; Quantum Field Theories; Quantum Field Theory; Quantum numbers; Quantum Physics; Quarks; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Tensors; Phenomenological Models; QCD Phenomenology
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP10(2019)256

A
bstract
The LHCb collaboration have recently updated their analysis of the resonant
J/ 𝜓 p
mass spectrum in the decay
Λ
b
0
→ J/𝜓 p K
−
, making use of their combined Run 1 and Run 2 data. In the updated analysis, three narrow states,
P
c
(4312)
+
,
P
c
(4440)
+
, and
P
c
(4457)
+
, are observed. The spin-parity assignments of these states are not yet known. We interpret these narrow resonances as compact hidden-charm diquark-diquark- antiquark pentaquarks. Using an effective Hamiltonian, based on constituent quarks and diquarks, we calculate the pentaquark mass spectrum for the complete SU (3)
F
lowest
S
- and
P
-wave multiplets, taking into account dominant spin-spin, spin-orbit, orbital and tensor interactions. The resulting spectrum is very rich and we work out the quark flavor compositions, masses, and
J
P
quantum numbers of the pentaquarks. However, heavy quark symmetry restricts the observable states in Λ
b
-baryon, as well as in the decays of the other weakly-decaying
b
-baryons, Ξ
b
and Ω
b
. In addition, some of the pentaquark states are estimated to lie below the
J/ 𝜓 p
threshold in Λ
b
-decays (and corresponding thresholds in Ξ
b
- and Ω
b
-decays). They decay via
c
c
¯
annihilation into light hadrons or a dilepton pair, and are expected to be narrower than the
P
c
-states observed. We anticipate their discovery, as well as of the other pentaquark states present in the spectrum at the LHC, and in the long-term future at a Tera-
Z
factory.