Quasinormal modes for quarkonium in a plasma with magnetic fields

Abstract

Heavy vector mesons detected after a heavy ion collision are important sources of information about the quark gluon plasma. The fraction of such particles that survive the plasma phase and reach the detectors is related to the dissociation degree inside the thermal medium. A consistent picture for the thermal behavior of charmonium and bottomonium quasi-states in a thermal medium was obtained recently using a holographic bottom up model. This model captures the heavy flavour spectroscopy of masses and decay constants in the vacuum (zero temperature) and is consistently extended to finite temperature. The spectral functions that emerge provide a description of the dissociation process in terms of the broadening of the quasi-state peaks with temperature. The holographic approach makes it possible to determine also the quasinormal modes. They are gravity solutions representing the quasi-particle states in the thermal medium, with complex frequencies related to the thermal mass and width. The quasinormal modes for charmonium and bottomonium have been studied very recently and a consistent description of the dissociation process was found.An additional factor can affect the dissociation process: strong magnetic fields are expected to be present when the plasma is formed by non-central heavy ion collisions. So, it is important to understand the effect of such fields on the heavy meson dissociation scenario. Here we extend the holographic determination of quasinormal modes for the case when magnetic fields are present. The real and imaginary parts of the mode frequencies are determined for different values of background eB field. The associated dispersion relations for heavy quarks moving inside the plasma are also investigated for both cc and bb . *

Thermal properties of light mesons from holography

“…A more straightforward method, which maps the pole mass and thermal width to the real and imaginary parts of the complex frequency of the corresponding quasi-normal mode (QNM) [80,81], was discussed in ref. [82] and applied in holographic QCD [83][84][85][86]. There are also discussions about Debye screening masses extracted from the spatial correlation functions of CT -odd operator TrF µνF µν [87,88], the pseudo-scalar glueballs [89] and the Polyakov loops [90].…”

Different approach to decay constants in AdS/QCD models

“…In the paper [31], authors discuss a deformed version of static quadratic soft wall model dilaton to address masses and decay constants for the heavy vector quarkonium. The proposed dilaton has the form…”

“…In this approach, authors study the effect of a dilaton field TABLE I. Comparative of the calculated decay constants using the Braga-Ferreira proposal [31] with the formula (22). The first column shows the experimental results obtained from [32].…”

Effects of beta function on mass and melting temperature for scalar glueballs in AdS/QCD models at finite temperature

“…This was an advance in relation to hard wall models because in this case the model produced linear Regge trajectories for the mass spectrum of light mesons, but later it was necessary to introduce improvements to describe other hadron properties, or to include baryons correctly. Common extensions to soft wall models considers different asymptotically AdS metrics and/or dilatons beyond the quadratic one (e.g., see [17][18][19][20][21]), but some authors have also considered bulk masses depending on the holographic coordinate (e.g., see [22][23][24][25][26][27]). The later alternative has been particularly useful in soft wall models to study barionic sector [26,27], because in this case the dilaton is decoupled in equation of motions [28],…”