117824383
Violation of equivalence principle in Brans-Dicke theory
We show that quantum fluctuations should violate the weak equivalence principle in the Brans - Dicke theory, which implies that the Jordan frame can no longer be interpreted as physical. In the Pauli frame the violation of the equivalence principle could be attributed to the existence of the dilatonic fifth force. We argue that the present fifth force experiments could put a much more stringent constraint on the Brans - Dicke coupling constant than accepted so far.
12520342
DIRAC QUANTIZATION OF RESTRICTED QCD
We discuss the quantization of the restricted gauge theory of SU(2) QCD regarding it as a second-class constraint system, and construct the BRST symmetry of the constrained system in the framework of the improved Dirac quantization scheme. Our analysis tells that one could efficiently quantize the restricted QCD under the BRST symmetry as if it is a first-class constraint system.
16229635
Dilatonic dark matter and unified cosmology: a new paradigm
We study the possibility that the dilaton - the fundamental scalar field which exists in all existing unified field theories - plays the role of the dark matter of the universe. We find that the condition for the dilaton to be the dark matter strongly restricts its mass to be around 0.5 keV or 270 MeV. For the other mass ranges, the dilaton either undercloses or overcloses the universe. The 0.5 keV dilaton has a free-streaming distance of about 1.4 Mpc and becomes an excellent candidate for warm dark matter, while the 270 MeV one has a free-streaming distance of about 7.4 pc and becomes cold dark matter. We discuss the possible ways to detect the dilaton experimentally.
119290148
Vacuum tunneling in gravity
Topologically non-trivial vacuum structures in gravity models with Cartan variables (vielbein and contortion) are considered. We study the possibility of vacuum spacetime tunneling in Einstein gravity assuming that the vielbein may play a fundamental role in quantum gravitational phenomena. It has been shown that in the case of RP3 space topology, the tunneling between non-trivial topological vacuums can be realized by means of Eguchi?Hanson gravitational instanton. In the Riemann?Cartan geometric approach to quantum gravity, the vacuum tunneling can be provided by means of contortion quantum fluctuations. We define a double self-duality condition for the contortion and give explicit self-dual configurations which can contribute to vacuum tunneling amplitude.
12642120
Anti-de Sitter Black Holes, Thermal Phase Transition and Holography in Higher Curvature Gravity
We study anti\char21{}de Sitter black holes in the Einstein-Gauss-Bonnet and the generic ${R}^{2}$ gravity theories, evaluate different thermodynamic quantities, and also examine the possibilities of Hawking-Page\char21{}type thermal phase transitions in these theories. In the Einstein theory, with a possible cosmological term, one observes a Hawking-Page phase transition only if the event horizon is a hypersurface of positive constant curvature $(k=1).$ But, with the Gauss-Bonnet and/or the $(\mathrm{Riemann}{)}^{2}$ interaction terms, there may occur a similar phase transition for a horizon of negative constant curvature $(k=\ensuremath{-}1).$ We examine the finite coupling effects, and find that $Ng5$ could trigger a Hawking-Page phase transition in the latter theory. For the Gauss-Bonnet black holes, one relates the entropy of the black hole to a variation of the geometric property of the horizon based on the first law and Noether charge. With a $(\mathrm{Riemann}{)}^{2}$ term, however, we can do this only approximately, and the two results agree when ${r}_{H}\ensuremath{\gg}L,$ the size of the horizon is much bigger than the AdS curvature scale. We establish some relations between bulk data associated with the AdS black hole and boundary data defined on the horizon of the AdS geometry. Following a heuristic approach, we estimate the difference between Hubble entropy $({\mathcal{S}}_{H})$ and Bekenstein-Hawking entropy $({\mathcal{S}}_{\mathrm{BH}})$ with a $(\mathrm{Riemann}{)}^{2}$ term, which, for $k=0$ and $k=\ensuremath{-}1,$ implies ${\mathcal{S}}_{\mathrm{BH}}l~{\mathcal{S}}_{H}.$
121597932
Gravitating 't Hooft Monopoles
The 't Hooft magnetic monopole solution of the SO(3) Higgs model generates, when coupled to gravity, a geometry which for large distances is of the Reissner--Nordstroem form corresponding to a (magnetic) charge 1/e. The Higgs fields can contribute a cosmological term. In the absence of scalar fields the corresponding Wu--Yang solution of the SO(3) gauge theory still generates the Reissner--Nordstroem geometry. (AIP)
121563333
C-projection and monopole condensation in QCD
We show that the monopole condensation is responsible for the confinement. To demonstrate this we present a new gauge invariant integral expression of the one-loop QCD effective action which has no infra-red divergence, and show that the color reflection invariance ("the C-projection") assures the gauge invariance and the stability of the monopole condensation.
121443233
MONOPOLE CONDENSATION AND MASS GAP IN SU(3) QCD
We demonstrate the monopole condensation in SU(3) QCD. We first discuss the gauge independent and Weyl symmetric Abelian (Cho-Duan-Ge) decomposition of the SU(3) QCD, and present a new gauge invariant integral expression of the one-loop effective action which has no infrared divergence. Integrating it gauge invariantly imposing the color reflection invariance ("the C-projection") we show that the effective potential generates the stable monopole condensation which generates the mass gap.