23,550 research outputs found
Chiral Boson Theory on the Light-Front
The {\it front form} framework for describing the quantized theory of chiral
boson is discussed. It avoids the conflict with the requirement of the
principle of microcausality as is found in the conventional equal- time
treatment. The discussion of the Floreanini-Jackiw model and its modified
version for describing the chiral boson becomes very transparent on the
light-front.Comment: 9 pages, plain Late
Perspectives of Light-Front Quantized Field Theory: Some New Results
Some basic topics in the light-front (LF) quantization of relativistic field
theory are reviewed. It is argued that the LF quantization is equally
appropriate as the conventional one and that they lead, assuming the micro-
causality principle, to the same physical content. This is confirmed in the
studies on the LF of the spontaneous symmetry breaking (SSB), of the degenerate
vacua in Schwinger model (SM) and Chiral SM (CSM), of the chiral boson theory,
and of the QCD in covariant gauges among others. The discussion on the LF is
more economical and more transparent. In the context of the Dyson-Wick pertur-
bation theory the relevant popagators in the front form theory are causal. The
Wick rotation can then be performed to employ the Euclidean space integrals in
momentum space. The lack of manifest covariance becomes tractable, and still
more so if we employ, as discussed in the text, the Fourier transform of the
fermionic field based on a special construction of the LF spinor. The fact that
the hyperplanes constitute characteristic surfaces of the hyper-
bolic partial differential equation is found irrelevant in the quantized
theory.Comment: 50 pages, plain Latex, Invited article for "Saga of Field Theory:
From Points to Strings", Eds., A.N. Mitra et al., Indian National Science
Academy-INSA, Indi
Acceleration and Deceleration in Curvature Induced Phantom Model of the Late and Future Universe, Cosmic Collapse as Well as its Quantum Escape
Here, cosmology of the late and future universe is obtained from
-gravity with non-linear curvature terms and ( being the
Ricci scalar curvature). It is different from -dark enrgy models, where
non-linear curvature terms are taken as gravitational alternative of dark
energy. In the present model, neither linear nor no-linear curvature terms are
taken as dark energy. Rather, dark energy terms are induced by curvature terms
in the Friedmann equation derived from -gravitational equations. It has
advantage over - dark energy models in the sense that the present model
satisfies WMAP results and expands as during matter-dominance.
So, it does not have problems due to which -dark energy models are
criticized. Curvature-induced dark energy, obtained here, mimics phantom.
Different phases of this model, including acceleration and deceleration during
phantom phase, are investigated here.It is found that expansion of the universe
will stop at the age ( being the present
age of the universe) and after this epoch, it will contract and collapse by the
time . Further,it is shown that universe will
escape predicted collapse (obtained using classical mechanics) on making
quantum gravity corrections relevant near collapse time due to extremely high
energy density and large curvature analogous to the state of very early
universe. Interestingly, cosmological constant is also induced here, which is
very small in classical domain, but very high in quantum domain.Comment: 33 page
- …