61 research outputs found
Gravitational waves generated from the cosmological QCD phase transition within AdS/QCD
We study the gravitational waves produced by the collision of the bubbles as
a probe for the cosmological first order QCD phase transition, considering
heavy static quarks. Using AdS/QCD and the correspondence between a first order
Hawking-Page phase transition and confinement-deconfinement phase transition,
we find the spectrum and the strain amplitude of the gravitational wave within
the hard and soft wall models. We postulate the duration of the phase
transition corresponds to the evaporation time of the black hole in the five
dimensional dual gravity space, and thereby obtain a bound on the string length
in the space and correspondingly on the duration of the QCD phase transition.
We also show that IPTA and SKA detectors will be able to detect these
gravitational waves, which can be an evidence for the first order deconfinement
transition.Comment: v2: The effects of sound waves and the magnetohydrodynamic turbulence
on the GW spectrum have been studied. Version published in PL
The cosmic QCD phase transition with dense matter and its gravitational waves from holography
Consistent with cosmological constraints, there are scenarios with the large
lepton asymmetry which can lead to the finite baryochemical potential at the
cosmic QCD phase transition scale. In this paper, we investigate this
possibility in the holographic models. Using the holographic renormalization
method, we find the first order Hawking-Page phase transition, between
Reissner-Nordstrm AdS black hole and thermal charged AdS space,
corresponding to the de/confinement phase transition. We obtain the
gravitational wave spectra generated during the evolution of bubbles for a
range of the bubble wall velocity and examine the reliability of the scenarios
and consequent calculations by gravitational wave experiments.Comment: 18 pages , 4 figures, references and new discussions added, accepted
to be published in Phys. Lett.
Jets in a strongly coupled anisotropic plasma
In this paper, we study the dynamics of the light quark jet moving through
the static, strongly coupled , anisotropic plasma with and
without charge. The light quark is presented by a point-like initial condition
falling string in the context of the AdS/CFT. We calculate the stopping
distance of the light quark in the anisotropic medium and compare it with its
isotropic value. By studying the falling string in the beam direction and
transverse direction, we find that the jet quenching increases in both
directions. Although, the enhancement of quenching is larger in the beam
direction. Also, the suppression of stopping distance is more prominent when
the anisotropic plasma have the same temperature as the isotropic plasma.Comment: Minor misprints corrected, some references added, and some figures
change
Holographic energy loss in non-relativistic backgrounds
In this paper, we study some aspects of energy loss in non-relativistic
theories from holography. We analyze the energy lost by a rotating heavy point
particle along a circle of radius with angular velocity in
theories with general dynamical exponent and hyperscaling violation
exponent . It is shown that this problem provides a novel perspective
on the energy loss in such theories. A general computation at zero and finite
temperature is done and it is shown that how the total energy loss rate depends
non-trivially on two characteristic exponents . We find that at
zero temperature there is a special radius where the energy loss is
independent of different values of . Also at zero temperature,
there is a crossover between a regime in which the energy loss is dominated by
the linear drag force and by the radiation because of the acceleration of the
rotating particle. We find that the energy loss of the particle decreases by
increasing and . We note that, unlike in the zero temperature,
there is no special radius at finite temperature case.Comment: 16 pages, major revision of finite temperature analysi
Towards a holographic quark-hadron continuity
We study dense nuclear and quark matter within a single microscopic approach,
namely the holographic Sakai-Sugimoto model. Nuclear matter is described via
instantons in the bulk, and we show that instanton interactions are crucial for
a continuous connection of chirally broken and chirally symmetric phases. The
continuous path from nuclear to quark matter includes metastable and unstable
stationary points of the potential, while the actual chiral phase transition
remains of first order, as in earlier approximations. We show that the model
parameters can be chosen to reproduce low-density properties of nuclear matter
and observe a non-monotonic behavior of the speed of sound as a function of the
baryon chemical potential, as suggested by constraints from QCD and
astrophysics.Comment: 28+19 pages, 5 figures; v2: clarifications and references added,
version to appear in JHE
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