575 research outputs found
Bounds on quantum gravity parameter from the NJL effective model of QCD
Existence of a minimal measurable length, as an effective cutoff in the
ultraviolet regime, is a common feature of all approaches to the quantum
gravity proposal. It is widely believed that this length scale will be of the
order of the Planck length , where
is a dimensionless parameter that should be
fixed only by the experiments. This issue can be taken into account through the
deformed momentum spaces with compact topologies. In this paper, we consider
minimum length effects on the physical quantities related to three parameters
of the Nambu-Jona-Lasinio effective model of QCD by means of the
deformed measure which is defined on compact momentum space with topology. This measure is suggested by the doubly special relativity
theories, Snyder deformed spaces, and the deformed algebra that is obtained in
the light of the stability theory of Lie algebras. Using the current
experimental data of the particle physics collaboration, we constraint quantum
gravity parameter and we compare our results with bounds that are
arisen from the other experimental setups.Comment: 10 pages, no figure, accepted for publication in Europhysics Letter
Gravity's rainbow: a bridge between LQC and DSR
The doubly special relativity (DSR) theories are investigated in order to
take into account an observer-independent length scale in special relativity
framework. It is widely believed that any quantum theory of gravity would
reduce to a DSR model at the flat limit when purely gravitational and quantum
mechanical effects are negligible. Gravity's rainbow is a simple generalization
of DSR theories to incorporate gravity. In this paper, we show that the
effective Friedmann equations that are suggested by loop quantum cosmology
(LQC) can be exactly reobtained in rainbow cosmology setup. The deformed
geometry of LQC then completely fixes the modified dispersion relation and
results in unique DSR model. In comparison with standard LQC scenario where
only the geometry is modified, both of the geometry and matter parts get
modifications in our setup. In this respect, we find that the total number of
microstates for the universe is finite which suggests the statistical origin
for the energy and entropy density bounds. These results explicitly show that
the DSR theories are appropriate candidates for the flat limit of loop quantum
gravity.Comment: 10 pages, 4 figures, Refs. adde
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