110,500 research outputs found
Interpolating Action for Strings and Membranes - a Study of Symmetries in the Constrained Hamiltonian Approach
A master action for bosonic strings and membranes, interpolating between the
Nambu--Goto and Polyakov formalisms, is discussed. The role of the gauge
symmetries vis-\`{a}-vis reparametrization symmetries of the various actions is
analyzed by a constrained Hamiltonian approach. This analysis reveals the
difference between strings and higher branes, which is essentially tied to a
degree of freedom count. The cosmological term for membranes follows naturally
in this scheme. The conncetion of our aproach with the Arnowitt--Deser--Misner
representation in general relativity is illuminated.Comment: LaTex, 23 pages; discussion on ADM representation included and new
references adde
Hamiltonian embedding of the massive Yang-Mills theory and the generalized St\"uckelberg formalism
Using the general notions of Batalin, Fradkin, Fradkina and Tyutin to convert
second class systems into first class ones, we present a gauge invariant
formulation of the massive Yang-Mills theory by embedding it in an extended
phase space. The infinite set of correction terms necessary for obtaining the
involutive constraints and Hamiltonian is explicitly computed and expressed in
a closed form. It is also shown that the extra fields introduced in the
correction terms are exactly identified with the auxiliary scalars used in the
generalized St\"uckelberg formalism for converting a gauge noninvariant
Lagrangian into a gauge invariant form.Comment: 31 pages, Latex, very minor changes, a concluding paragraph inserted,
version to appear in Nucl. Phys.
A Study on the structure of proton
The structure function of the proton has been investigated and has been found
to possess the power law behaviour in conformity with the empirical fits to the
experimental findings. We have estimated F(x, Q)/F(x,
Q) with the anomalous dimension D predicted from the
statistical model as an input and the result is found to be in good agreement
with the recent data available in the deep inelastic region.Comment: 3 page
Generalised Hamiltonian embedding of the Proca model
We convert the second class Proca model into a first class theory by using
the generalised prescription of Batalin, Fradkin and Tyutin. We then show how a
basic set of gauge invariant fields in the embedded model can be identified
with the fundamental fields in the proca model as well as with the observables
in the St\"uckelberg model or in the model involving the interaction of an
abelian 2-form field with the Maxwell field. The connection of these models
with the massive Kalb-Ramond model is also elucidated within a path integral
approach.Comment: 11 pages, Latex, No figur
Saturated-absorption spectroscopy: Eliminating crossover resonances using co-propagating beams
We demonstrate a new technique for saturated-absorption spectroscopy using
co-propagating beams that does not have the problem of crossover resonances.
The pump beam is locked to a transition and its absorption signal is monitored
while the probe beam is scanned. As the probe comes into resonance with another
transition, the pump absorption is reduced and the signal shows a Doppler-free
dip. We use this technique to measure hyperfine intervals in the line of
Rb with a precision of 70 kHz, and to resolve hyperfine levels in the
line of K that are less than 10 MHz apart.Comment: 3 pages, 4 figures. To appear in Optics Letter
Batalin-Tyutin Quantization of the (2+1) dimensional nonabelian Chern-Simons field theory
The (2+1) dimensional nonabelian Chern-Simons theory coupled to complex
scalar fields is quantized by using the Batalin-Tyutin canonical Hamiltonian
method which systematically embeds second-class constraint system into
first-class one. We obtain the gauge-invariant nonabelian Wess-Zumino type
action in the extended phase space.Comment: 11 pages, SNUTP 94-32, SOGANG-HEP 189/94, LaTe
The BFT Method With Chain Structure
We have constructed a modified BFT method that preserves the chain structure
of constraints. This method has two advantages: first, it leads to less number
of primary constraints such that the remaining constraints emerge
automatically; and second, it gives less number of independent gauge
parameters. We have applied the method for bosonized chiral Schwiger model. We
have constructed a gauge invariant embedded Lagrangian for this model.Comment: To appear in Phys. Lett.
Nonlinear behavior of vibrating molecules on suspended graphene waveguides
Suspended graphene waveguides were deposited on micron-scale periodic metal
(plasmonic) structures. Raman scattering of test molecules (B. Megaterium),
deposited on the waveguides' surface, exhibited azimuthal cycles upon rotation:
at these micron scales, spontaneous Raman ought to be independent of phase
matching conditions. In addition, we observed angular-selective quadratic
intensity dependence contrary to the typical linear behavior of spontaneous
Raman. The effects were observed at very modest pump laser intensities (<10
MW/cm2 at the sample surface, oftenly used in Raman experiments). We attributed
these observations to nonlinear coupling between the vibrating molecules and
surface plasmon polariton (SPP) modes at the molecular vibration frequency. It
was assessed that the polariton mode propagates through fairly long distances
(over 100 microns).Comment: 18 pages; 3 figures; a journal pape
Quantisation of second class systems in the Batalin-Tyutin formalism
We review the Batalin-Tyutin approach of quantising second class systems
which consists in enlarging the phase space to convert such systems into first
class. The quantisation of first class systems, it may be mentioned, is already
well founded. We show how the usual analysis of Batalin-Tyutin may be
generalised, particularly if one is dealing with nonabelian theories. In order
to gain a deeper insight into the formalism we have considered two specific
examples of second class theories-- the massive Maxwell theory (Proca model)
and its nonabelian extension. The first class constraints and the involutive
Hamiltonian are explicitly constructed. The connection of our Hamiltonian
approach with the usual Lagrangian formalism is elucidated. For the Proca model
we reveal the importance of a boundary term which plays a significant role in
establishing an exact identification of the extra fields in the Batalin-Tyutin
approach with the St\"uckelberg scalar. Some comments are also made concerning
the corresponding identification in the nonabelian example.Comment: 26 pages, Latex file, e-mail [email protected] SINP-TNP/94-
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