scholarly journals Two-particle contributions and nonlocal effects in the QCD sum rules for the axial vector tetraquark candidate Zc(3900)

2020 ◽  
Vol 35 (24) ◽  
pp. 2050138 ◽  
Author(s):  
Zhi-Gang Wang
Keyword(s):  
Sum Rules ◽  
Axial Vector ◽  
Feynman Diagrams ◽  
Spatial Distance ◽  
Particle Scattering ◽  
Nonlocal Effects ◽  
Qcd Sum Rules ◽  
Small Width ◽  
Scattering State ◽  
A Minor

In this article, we study the [Formula: see text] with the QCD sum rules in details by including the two-particle scattering state contributions and nonlocal effects between the diquark and antidiquark constituents. The two-particle scattering state contributions cannot saturate the QCD sum rules at the hadron side, the contribution of the [Formula: see text] plays an unsubstitutable role, we can saturate the QCD sum rules with or without the two-particle scattering state contributions. If there exists a repulsive barrier or spatial distance between the diquark and antidiquark constituents, the Feynman diagrams can be divided into the factorizable and nonfactorizable diagrams. The factorizable diagrams consist of two-colored clusters and lead to a stable tetraquark state. The nonfactorizable Feynman diagrams correspond to the tunneling effects, which play a minor important role in the QCD sum rules, and are consistent with the small width of the [Formula: see text]. It is feasible to apply the QCD sum rules to study the tetraquark states, which begin to receive contributions at the order [Formula: see text], not at the order [Formula: see text].

scholarly journals Finite Temperature QCD Sum Rules: A Review

2017 ◽  
Vol 2017 ◽  
pp. 1-24 ◽  
Author(s):  
Alejandro Ayala ◽  
C. A. Dominguez ◽  
M. Loewe
Keyword(s):  
Finite Temperature ◽  
Chemical Potential ◽  
Sum Rules ◽  
Light Quark ◽  
Axial Vector ◽  
Heavy Ion ◽  
Qcd Sum Rules ◽  
Rho Meson ◽  
Ion Collisions ◽  
Rule Method

The method of QCD sum rules at finite temperature is reviewed, with emphasis on recent results. These include predictions for the survival of charmonium and bottonium states, at and beyond the critical temperature for deconfinement, as later confirmed by lattice QCD simulations. Also included are determinations in the light-quark vector and axial-vector channels, allowing analysing the Weinberg sum rules and predicting the dimuon spectrum in heavy-ion collisions in the region of the rho-meson. Also, in this sector, the determination of the temperature behaviour of the up-down quark mass, together with the pion decay constant, will be described. Finally, an extension of the QCD sum rule method to incorporate finite baryon chemical potential is reviewed.

scholarly journals Analysis of the Zc(4200) as axial-vector molecule-like state

2015 ◽  
Vol 30 (30) ◽  
pp. 1550168 ◽  
Author(s):  
Zhi-Gang Wang
Keyword(s):  
Experimental Data ◽  
Sum Rules ◽  
Axial Vector ◽  
Vector Current ◽  
Axial Vector Current ◽  
Qcd Sum Rules ◽  
Color Octet ◽  
Type Molecule

In this paper, we assume the [Formula: see text] as the color octet–octet type axial-vector molecule-like state, and construct the color octet–octet type axial-vector current to study its mass and width with the QCD sum rules. The numerical values [Formula: see text] and [Formula: see text] are consistent with the experimental data [Formula: see text] and [Formula: see text], and support assigning the [Formula: see text] to be the color octet–octet type molecule-like state with [Formula: see text]. Furthermore, we discuss the possible assignments of the [Formula: see text], [Formula: see text] and [Formula: see text] as the diquark–antidiquark type tetraquark states with [Formula: see text].

scholarly journals Assignments of the X 4140 , X 4500 , X 4630 , and X 4685 Based on the QCD Sum Rules

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhi-Gang Wang
Keyword(s):  
Excited State ◽  
Sum Rules ◽  
Molecular State ◽  
Tetraquark State ◽  
Qcd Sum Rules ◽  
Scattering States ◽  
Scattering State ◽  
Good Agreement

In this article, we take into account our previous calculations based on the QCD sum rules, and tentatively assign the X 4630 as the D s ∗ D ¯ s 1 − D s 1 D ¯ s ∗ tetraquark molecular state or c s P c ¯ s ¯ A + c s A c ¯ s ¯ P tetraquark state with the J P C = 1 − + , and assign the X 3915 and X 4500 as the 1S and 2S c s A c ¯ s ¯ A tetraquark states, respectively, with the J P C = 0 + + . Then, we extend our previous works to investigate the LHCb’s new tetraquark candidate X 4685 as the first radial excited state of the X 4140 with the QCD sum rules and obtain the mass M X = 4.70 ± 0.12   GeV , which is in very good agreement with the experimental value 4684 ± 7 − 16 + 13   MeV . Furthermore, we investigate the two-meson scattering state contributions in details and observe that the two-meson scattering states alone cannot saturate the QCD sum rules, the contributions of the tetraquark states play an unsubstitutable role, and we can saturate the QCD sum rules with or without the two-meson scattering states.

TWIST-THREE DISTRIBUTION AMPLITUDES AND OCTET CURRENT DECAY CONSTANTS OF η AND η': A QCD SUM RULE APPROACH

2009 ◽  
Vol 18 (05n06) ◽  
pp. 1318-1323
Author(s):  
J. P. SINGH
Keyword(s):  
Sum Rules ◽  
Light Quark ◽  
Axial Vector ◽  
Vector Current ◽  
Axial Vector Current ◽  
Qcd Sum Rules ◽  
Sum Rule ◽  
Decay Constants ◽  
Current Decay ◽  
Rule Approach

We investigate twist-three distribution amplitudes (DAs) of η and η' using QCD sum rules. Zeroth moments of light quark DAs of η and η' are evaluated and compared with those found in other approaches. The decay constants of the octet axial vector current in the η and η' system are also estimated.

scholarly journals Axial vector (JPC= 1++) charmonium and bottomonium hybrid mass predictions with QCD sum-rules

2012 ◽  
Vol 39 (12) ◽  
pp. 125003 ◽  
Author(s):  
D Harnett ◽  
R T Kleiv ◽  
T G Steele ◽  
Hong-ying Jin
Keyword(s):  
Sum Rules ◽  
Axial Vector ◽  
Qcd Sum Rules

scholarly journals ANALYSIS OF MASS MODIFICATIONS OF THE VECTOR AND AXIAL VECTOR HEAVY MESONS IN THE NUCLEAR MATTER WITH THE QCD SUM RULES

2013 ◽  
Vol 28 (14) ◽  
pp. 1350049 ◽  
Author(s):  
ZHI-GANG WANG
Keyword(s):  
Nuclear Matter ◽  
Sum Rules ◽  
Axial Vector ◽  
Vector Mesons ◽  
Qcd Sum Rules ◽  
Heavy Mesons ◽  
Scattering Lengths ◽  
Mass Shifts

In this paper, we calculate the mass modifications of the vector and axial vector mesons D*, B*, D1 and B1 in the nuclear matter with the QCD sum rules, and obtain the mass-shifts δMD* = -71 MeV , δMB* = -380 MeV , δMD1 = 72 MeV , δMB1 = 264 MeV , and the scattering lengths aD* = -1.07 fm , aB* = -7.17 fm , aD1 = 1.15 fm and aB1 = 5.03 fm for the D*N, B*N, D1N and B1N interactions, respectively.

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