Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules

Abstract

Chiral symmetry and its spontaneous breaking play an important role both in the light hadron and heavy hadron systems. In this work, we shall review the investigations on the chiral corrections to the properties of the heavy mesons and baryons within the framework of the chiral perturbation theory (χPT). We will also review the scatterings of the light pseudoscalar mesons and heavy hadrons. Moreover, the modern nuclear force was built upon the chiral effective field theory (χEFT). In the past decades many new hadron states were observed experimentally. A large group of these states are near-threshold resonances, such as the charged charmoniumlike Z c and Z cs states, bottomoniumlike Z b states, hidden-charm pentaquark P c and P cs states and the doubly charmed T cc state etc. They are very good candidates of the loosely bound molecular states composed of a pair of charmed hadrons. The same chiral dynamics not only governs the nuclei and forms the deuteron, but also dictates the above shallow bound states or resonances. We will perform an extensive review on the progress on the heavy hadronic molecular states within the framework of χEFT.

$Σ_cΣ_c$ interactions in chiral effective field theory

“…However, since the discoveries of the D * s0 (2317) [3] and X(3872) [4] in 2003, a large number of states that cannot be classified into conventional hadrons are continuously reported [5]. Different pictures have been proposed to understand the nature of these exotic states, such as the compact multiquark states, loosely bound hadronic molecules, and kinetic effects, etc [6][7][8][9][10][11][12][13][14][15]. Many exotic states are near the thresholds of a pair of heavy hadrons from several to several tens MeVs, which makes the hadronic molecular picture the popular one.…”

“…The chiral effective field theory (χEFT) has been widely applied to describe the nuclear forces (see [93][94][95][96][97] for reviews), as well as the D s (2317) [98], T cc [99], P c [26,32], and P cs [37] states (see the recent review [15]). In the framework of χEFT, we include the leading order (LO) contact term, onepion exchange (OPE), and two-pion exchange (TPE) contributions to account for the short-, long-, and intermediate-range interactions of the doubly charmed di-baryon systems, respectively.…”

Fully-charm and -bottom pentaquarks in a Lattice-QCD inspired quark model

“…Very detailed reviews have been published on the current state of the subject; see for instance Refs. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In the last few years, more tetraquark candidates have been reported such as the charged charmonium-like tetraquark with strangeness X 0,1 (2900) [19,20]; X(2600) [21]; X(1835), X(2120) and X(2370) [22]; Z cs (3985) [23]; Z cs (4000), Z cs (4220), X(4630) and X(4685) [24]; Y (4230) and Y (4500) [25]; the hidden charm structure ψ 2 (3823) [26,27]; and the doubly charmed tetraquark T + cc [28,29].…”

Heavy-light hybrid mesons with different spin-parities

“…In the past two decades, with the development of experimental facilities, starting with the observation of the X(3872) [1], we witness the observations of many exotic hadrons (for more information see for instance Refs. [2][3][4][5][6][7][8][9][10][11]).…”