Glueball Spectroscopy Research Articles

Glueball spectroscopy in lattice QCD using gradient flow

Removing ultraviolet noise from the gauge fields is necessary for glueball spectroscopy in lattice QCD. It is known that the Yang-Mills gradient flow method is an alternative approach instead of link smearing or link fuzzing in various aspects. In this work we study the application of the gradient flow technique to the construction of the extended glueball operators. We examine a simple application of the gradient flow method, which has some problems in glueball mass calculations at large flow time because of its nature of diffusion in space-time. To avoid this problem, the spatial links are evolved by the ``spatial gradient flow'', that is defined to restrict the diffusion to spatial directions only. We test the spatial gradient flow in calculations of glueball two-point functions and Wilson loops as a new smearing method, and then discuss its efficiency in comparison with the original gradient flow method and the conventional method. Furthermore, to demonstrate the feasibility of our proposed method, we determine the masses of the three lowest-lying glueball states, corresponding to the $0^{++}$, $2^{++}$ and $0^{-+}$ glueballs, in the continuum limit in the pure Yang-Mills theory.

Meson and glueball spectroscopy within the graviton soft-wall model

In this contribution we present results of the calculations of several hadronic spectra within the holographic graviton soft-wall (GSW) model. In particular, we studied and compared with data for the ground state and excitations of: glueballs, scalar, vector, axial and pseudo-scalar mesons. The GSW model is found to be capable to describe these observable with only few parameters.

Meson and glueball spectroscopy within the graviton soft wall model

The graviton soft wall (GSW) model provides a unified description of the scalar glueball and meson spectra with a unique energy scale. This success has led us to extend the analysis to the description of the spectra of other hadrons. We use this model to calculate masses of the odd and even ground states of glueballs for various spins, and show that the GSW model is able to reproduce the Regge trajectory of these systems. In addition, the spectra of the $\ensuremath{\rho}$, ${a}_{1}$ and $\ensuremath{\eta}$ mesons will be addressed. Results are in excellent agreement with current experimental data. Furthermore such an achievement is obtained without any additional parameters. Indeed, the only two parameters appearing in these spectra are those that were previously fixed by the light scalar meson and glueball spectra. Finally, in order to describe the $\ensuremath{\pi}$ meson spectrum, a suitable modification of the dilaton profile function has been included in the analysis to properly take into account the Goldstone realization of chiral symmetry. The present investigation confirms that the GSW model provides an excellent description of the spectra of mesons and glueballs with only a small number of parameters unveiling a relevant predicting power.

Top\u2013down holographic G-structure glueball spectroscopy at (N)LO in N and finite coupling

The top–down type IIB holographic dual of large-N thermal QCD as constructed in Mia et al. (Nucl Phys B 839:187, 2010) involving a fluxed resolved warped deformed conifold, its delocalized type IIA Strominger–Yau–Zaslow-mirror (SYZ-mirror) as well as its M-theory uplift constructed in Dhuria and Misra (JHEP 1311:001, 2013) – both in the finite coupling (g_smathop {sim }limits ^{<}1)/‘MQGP’ limit of Dhuria and Misra (JHEP 1311:001, 2013) – were shown explicitly to possess a local SU(3)/G_2-structure in Sil and Misra (Nucl Phys B 910:754, 2016). Glueballs spectra in the finite-gauge-coupling limit (and not just large ’t Hooft coupling limit) – a limit expected to be directly relevant to strongly coupled systems at finite temperature such as QGP (Natsuume in String theory and quark–gluon plasma, 2007) – has thus far been missing in the literature. In this paper, we fill this gap by calculating the masses of the 0^{++}, 0^{-+},0^{{-}{-}}, 1^{++}, 2^{++} (‘glueball’) states (which correspond to fluctuations in the dilaton or complexified two-forms or appropriate metric components) in the aforementioned backgrounds of G-structure in the ‘MQGP’ limit of Dhuria and Misra (JHEP 1311:001, 2013). We use WKB quantization conditions on one hand and impose Neumann/Dirichlet boundary conditions at an IR cut-off (‘r_0’)/horizon radius (‘r_h’) on the solutions to the equations of motion on the other hand. We find that the former technique produces results closer to the lattice results. We also discuss the r_h=0 limits of all calculations. In this context we also calculate the 0^{++}, 0^{{-}{-}},1^{++}, 2^{++} glueball masses up to Next to Leading Order (NLO) in N and find a frac{g_sM^2}{N}(g_sN_f)-suppression similar to and further validating semi-universality of NLO corrections to transport coefficients, observed in Sil and Misra (Eur Phys J C 76(11):618, 2016).

Glueball spectroscopy in a relativistic many-body approach to hadronic structure.

A comprehensive, relativistic many-body approach to hadron structure is advanced based on the Coulomb gauge QCD Hamiltonian. Our method incorporates standard many-body techniques which render the approximations amenable to systematic improvement. Using BCS variational methods, dynamic chiral symmetry breaking naturally emerges and both quarks and gluons acquire constituent masses. Gluonia are studied both in the valence and in the collective, random phase approximations. Using representative values for the strong coupling constant and string tension, calculated quenched glueball masses are found to be in remarkable agreement with lattice gauge theory.

Glueball and baryon production in parton showers.

We propose a topological model for the confining-phase transition based on string formation. Our glueball is a string loop, our baryon a ssY-shaped junction. If ${\mathit{f}}_{2}$(1720) is a glueball, we estimate its production rate to be of order a few percent in the cc\ifmmode\bar\else\textasciimacron\fi{} system and \ensuremath{\sim}5% for inclusive decay of the bb\ifmmode\bar\else\textasciimacron\fi{} system. A numerical simulation shows that glueball and baryon production depend strongly on the shape of the parton shower. These shape dependences may prove useful as diagnostics for jetiness. If our model is correct, ${\mathrm{\ensuremath{\chi}}}_{\mathit{c}}$, \ensuremath{\psi}(2S), and \ensuremath{\Upsilon} will be excellent sources for studying glueball spectroscopy.

Glueball spectroscopy from strong coupling expansions in hamiltonian lattice QCD

Abstract Masses of all the glueballs which are created by 6- or 7-link operators are calculated to order g−8 in pure SU(3) hamiltonian lattice gauge theory. Several low-lying states are found with masses m(0 ++∗ )∼ 1.4 m s , m(0 ++∗∗ ) ∼ 1.7 m s (∗ and ∗∗ stand for radial excitations and ms is the mass of the lowest 0++ state), m(0 −− ) ∼ 2.2 m s , m(1 +−∗ ) ∼ m(1.6 m s , m(1 −+ ) ∼ 1.8 m s , m(1 −−) ∼ 2.2 m s and m(2 ++ ) ∼ 1.3 m s . These values are obtained at the point g−2 ≅ 0.8, which lies near the scaling region.

Glueball spectroscopy in strongly coupled lattice gauge theories

We study the mass spectrum up to −7 (1−ε) logβ of pure three-dimensional lattice gauge theories with action β $$\mathop \sum \limits_P$$ χ(g P) for real irreducible χ and small β. Besides the lowest excitationm 0∼−4logβ, we find two nearly degenerate excited statesm 1,m 2 withm i∼−6logβ (i=1, 2) and (m 1−m 2) at leastO(β).

Glueball spectroscopy in 4d SU(3) lattice gauge theory (I)

We give a complete classification of states that can be constructed from spacelike Wilson loop operators up to length 8. This set of operators is considered in a Monte Carlo variational calculation. In part I of this paper we report Monte Carlo results from an 4 3.8 lattice, relying on Wilson loops up to length 6. We find a scaling window for the 0 ++ state, but no scaling for any other state.