Symbiotic soybean in acidified soil

Thermal relics in cosmology with bulk viscosity

“…The origin of the baryon number asymmetry in the Universe is still an unsolved problem [64,[82][83][84][85][86][87][88][89]. The success of the big bang nucleosynthesis [90,91] and the observations of Cosmic Microwave Background anisotropies (combined with the large structure of the Universe [92,93]) show that the parameter characterizing such an asymmetry is of the order…”

The Cosmological Constant Problem and Nonlocal Quantum Gravity

“…One possible explanation for the accelerating expansion of the universe is a small cosmological constant corresponding to a vacuum energy density, ρ vac ∼ (2.4 × 10 −3 eV) 4 . There have been many attempts to solve the cosmological constant problem (CCP).…”

“…Weinberg's theorem [3] disallows all adjustment models involving extra fields such as a dynamical scalar field. Higher-dimensional models of the brane-bulk type with finite volume extra-dimensions do not avoid finetuning [4].…”

Model of the universe including dark energy accounted for by both a quintessence field and a (negative) cosmological constant

“…In a deSitter space the presence of an event horizon, signifying causally disconnected regions of space, implies the absence of asymptotic particle states which are needed to define transition amplitudes [9,10]. Due to the above there is a renewed interest in exponential quintessence, because in several scenarios exponential potentials can reproduce the present acceleration and predict future deceleration, so again string theory has well defined asymptotic states [10,11].…”

“…Worthwhile to notice that exponential quintessence had been so far overlooked on fine tuning arguments, but several authors have recently pointed out that the degree of fine tuning needed in these scenarios is no more than in others usually accepted [10][11][12].…”