https://doi.org/10.1140/epjc/s10052-017-4921-7
Regular Article - Theoretical Physics
Top–down holographic G-structure glueball spectroscopy at (N)LO in N and finite coupling
Department of Physics, Indian Institute of Technology, Roorkee, Uttaranchal, 247 667, India
* e-mail: krusldph@iitr.ac.in
Received:
25
April
2017
Accepted:
15
May
2017
Published online:
9
June
2017
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 (
)/‘MQGP’ limit of Dhuria and Misra (JHEP 1311:001, 2013) – were shown explicitly to possess a local 
-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 
(‘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 (‘
’)/horizon radius (‘
’) 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 
limits of all calculations. In this context we also calculate the 
glueball masses up to Next to Leading Order (NLO) in N and find a 
-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).
© The Author(s), 2017
