Is the exotic 0−− glueball a pure gluon state?

Abstract

We present a new calculation of the mass and width of the exotic 0 −− glueball in the framework of the QCD sum rules. We next construct a new current which couples to a pure 0 −− gluon state and derive consistent and stable sum rules. A previously used current in this approach was shown to be inconsistent. We obtain for this state a mass MG = 6.3 +0.8 −1.1 GeV and an upper limit for the total width ΓG ≤ 235 MeV. These values can be used as an important guide for the experimental search of this exotic state. We argue that the mixing of this glueball state with 0 −− tetraquark is very small. Therefore, the exotic 0 −− glueball can be considered as a pure gluon state.

Exotic glueball 0±− states in QCD sum rules

“…The developed techniques of the helicity based current construction have been used to build new threegluon currents of minimal dimension that couple to the 0 ±− glueball states. Our previous QCD SRs results [31] on the 0 −− -glueball mass using a dimension-12 current, M G = 6.3 +0.8 −1.1 GeV, is in good agreement with our new estimation, Eq.(17). As one would expect, the current with higher dimension leads to a smaller coupling to the dimension-12 current with the glueball state [31]: F G = 67 ± 6 keV.…”

“…Our previous QCD SRs results [31] on the 0 −− -glueball mass using a dimension-12 current, M G = 6.3 +0.8 −1.1 GeV, is in good agreement with our new estimation, Eq.(17). As one would expect, the current with higher dimension leads to a smaller coupling to the dimension-12 current with the glueball state [31]: F G = 67 ± 6 keV. Therefore, the new current of minimal dimension represents the most possible configuration of 0 −− glueball.…”

“…From the new SR, we have found that the mass of the 0 −− glueball is very close to our previous result [31]. At the same time, the coupling of the new current to the glueball state has been found to be significantly larger compared to the dimension-12 current suggested in [31]. Therefore we conclude that the new current better represents the glueball state.…”

“…In our recent study [31,32] we proposed the 0 −− glueball current of dimension-12, which was used to obtain estimations of the mass, the decay constant and the width of the 0 −− glueball.…”

Mass and residue of $\Lambda (1405)$ Λ ( 1405 ) as hybrid and excited ordinary baryon

“…The hadrons with unusual internal structures, i.e. exotic resonances were classified as XY Z particles [3], glueballs [4], hybrids [5,6], meson molecules [7], tetraquarks [8], pentaquarks [9] and dibaryons [10]. Like other groups of exotic particles, an identification and classification of hybrid hadrons and calculation of their spectroscopic parameters are important for both revealing their inner organization and gaining new information on quantum chromodynamics (QCD).…”