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Register a new userScalar and Tensor Glueballs as Gravitons
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The bottom-up approach of the AdS/CFT correspondence leads to the study of field equations in an $AdS_5$ background and from their solutions to the determination of the hadronic mass spectrum. We extend the study to the equations of $AdS_5$ gravitons and determine from them the glueball spectrum. We propose an original presentation of the results which facilitates the comparison of the various models with the spectrum obtained by lattice QCD. This comparison allows to draw some phenomenological conclusions.
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The graviton solutions for the glueball spectrum of ref. cite{Rinaldi:2017wdn} interpreted in a different manner lead to very interesting results which we describe in this comment.
This compact review about gluonium focuses on a slate of theoretical efforts; among the many standing works, I have selected several that are meant to assist in the identification, among ordinary mesons, of the few Yang-Mills glueball configurations that populate the energy region below 3 GeV. This includes $J/psi$ radiative and vector-meson decays, studies of scalar meson mixing, of high-energy cross sections via the Pomeron and the odderon, glueball decays, etc. The weight of accumulated evidence seems to support the $f_0(1710)$ as having a large (and the largest) glueball component among the scalars, although no single observable by itself is conclusive. Further tests would be welcome, such as exclusive $f_J$ production at asymptotically high $s$ and $t$. No clear experimental candidates for the pseudoscalar or tensor glueball stand out yet, and continuing investigations trying to sort them out will certainly teach us much more about mesons.
We discovered a chiral enhancement in the production cross-sections of massive spin-2 gravitons, below the electroweak symmetry breaking scale, that makes them ideal dark matter candidates for the freeze-in mechanism. The result is independent on the physics at high scales, and points towards masses in the MeV range. The graviton is, therefore, a warm dark matter particle, as favoured by the small scale galaxy structures. We apply the novel calculation to a Randall-Sundrum model with three branes, showing a significant parameter space where the first two massive gravitons saturate the dark matter relic density.
We study two- and three-gluon glueballs of $C=+$ using the method of QCD sum rules. We systematically construct their interpolating currents, and find that all the spin-1 currents of $C=+$ vanish. This suggests that the ground-state spin-1 glueballs of $C=+$ do not exist within the relativistic framework. We calculate masses of the two-gluon glueballs with $J^{PC} = 0^{pm+}/2^{pm+}$ and the three-gluon glueballs with $J^{PC} = 0^{pm+}/2^{pm+}$. We propose to search for the $J^{PC} = 0^{-+}/2^{-pm}/3^{pm-}$ three-gluon glueballs in their three-meson decay channels in future BESIII, GlueX, LHC, and PANDA experiments.
Inflation is often described through the dynamics of a scalar field, slow-rolling in a suitable potential. Ultimately, this inflaton must be identified as the expectation value of a quantum field, evolving in a quantum effective potential. The shape of this potential is determined by the underlying tree-level potential, dressed by quantum corrections from the scalar field itself and the metric perturbations. Following [1], we compute the effective scalar field equations and the corrected Friedmann equations to quadratic order in both scalar field, scalar metric and tensor perturbations. We identify the quantum corrections from different sources at leading order in slow-roll, and estimate their magnitude in benchmark models of inflation. We comment on the implications of non-minimal coupling to gravity in this context.
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