2,019 research outputs found
Cobb-Douglas Production Function For Measuring Efficiency in Indian Agriculture: A Region-wise Analysis
The paper examines the production efficiency of agricultural system in four regions of India categorized as eastern, western, northern and southern regions using state level data for the period 2005-06 to 2013-14. Stochastic production frontier model using panel data, as proposed by Battese and Coelli (1995), has been used for estimating the efficiency variations taking an integrated effect model into consideration. State level mean efficiency estimates of regions ranges from 0.8824 to 0.3759 for 2005-06 to 2013-14. The statistically significant variables explaining inefficiencies in the agricultural production are total state road length per unit of area and share of agricultural NSDP to state NSDP. The major inputs were institutional credit, net irrigated area and consumption of both fertilizers and pesticide
Boundary Quantum Field Theories with Infinite Resonance States
We extend a recent work by Mussardo and Penati on integrable quantum field
theories with a single stable particle and an infinite number of unstable
resonance states, including the presence of a boundary. The corresponding
scattering and reflection amplitudes are expressed in terms of Jacobian
elliptic functions, and generalize the ones of the massive thermal Ising model
and of the Sinh-Gordon model. In the case of the generalized Ising model we
explicitly study the ground state energy and the one-point function of the
thermal operator in the short-distance limit, finding an oscillating behaviour
related to the fact that the infinite series of boundary resonances does not
decouple from the theory even at very short-distance scales. The analysis of
the generalized Sinh-Gordon model with boundary reveals an interesting
constraint on the analytic structure of the reflection amplitude. The roaming
limit procedure which leads to the Ising model, in fact, can be consistently
performed only if we admit that the nature of the bulk spectrum uniquely fixes
the one of resonance states on the boundary.Comment: 18 pages, 11 figures, LATEX fil
Boundary states for a free boson defined on finite geometries
Langlands recently constructed a map that factorizes the partition function
of a free boson on a cylinder with boundary condition given by two arbitrary
functions in the form of a scalar product of boundary states. We rewrite these
boundary states in a compact form, getting rid of technical assumptions
necessary in his construction. This simpler form allows us to show explicitly
that the map between boundary conditions and states commutes with conformal
transformations preserving the boundary and the reality condition on the scalar
field.Comment: 16 pages, LaTeX (uses AMS components). Revised version; an analogy
with string theory computations is discussed and references adde
Form-factors computation of Friedel oscillations in Luttinger liquids
We show how to analytically determine for the "Friedel
oscillations" of charge density by a single impurity in a 1D Luttinger liquid
of spinless electrons.Comment: Revtex, epsf, 4pgs, 2fig
String Theory near a Conifold Singularity
We demonstrate that type II string theory compactified on a singular
Calabi-Yau manifold is related to string theory compactified at the
self-dual radius. We establish this result in two ways. First we show that
complex structure deformations of the conifold correspond, on the mirror
manifold, to the problem of maps from two dimensional surfaces to . Using
two dimensional QCD we show that this problem is identical to string
theory. We then give an alternative derivation of this correspondence by
mapping the theory of complex structure deformations of the conifold to
Chern-Simons theory on . These results, in conjunction with similar
results obtained for the compactification of the heterotic string on , provide strong evidence in favour of S-duality between type II strings
compactified on a Calabi-Yau manifold and the heterotic string on .Comment: 10 pages, harvmac. Some changes to manuscript and a reference adde
Exact solutions for models of evolving networks with addition and deletion of nodes
There has been considerable recent interest in the properties of networks,
such as citation networks and the worldwide web, that grow by the addition of
vertices, and a number of simple solvable models of network growth have been
studied. In the real world, however, many networks, including the web, not only
add vertices but also lose them. Here we formulate models of the time evolution
of such networks and give exact solutions for a number of cases of particular
interest. For the case of net growth and so-called preferential attachment --
in which newly appearing vertices attach to previously existing ones in
proportion to vertex degree -- we show that the resulting networks have
power-law degree distributions, but with an exponent that diverges as the
growth rate vanishes. We conjecture that the low exponent values observed in
real-world networks are thus the result of vigorous growth in which the rate of
addition of vertices far exceeds the rate of removal. Were growth to slow in
the future, for instance in a more mature future version of the web, we would
expect to see exponents increase, potentially without bound.Comment: 9 pages, 3 figure
Edge Critical Behaviour of the 2-Dimensional Tri-critical Ising Model
Using previous results from boundary conformal field theory and
integrability, a phase diagram is derived for the 2 dimensional Ising model at
its bulk tri-critical point as a function of boundary magnetic field and
boundary spin-coupling constant. A boundary tri-critical point separates phases
where the spins on the boundary are ordered or disordered. In the latter range
of coupling constant, there is a non-zero critical field where the
magnetization is singular. In the former range, as the temperature is lowered,
the boundary undergoes a first order transition while the bulk simultaneously
undergoes a second order transition.Comment: 6 pages, RevTex, 3 postscript figure
Direct Calculation of Breather S Matrices
We formulate a systematic Bethe-Ansatz approach for computing bound-state
(``breather'') S matrices for integrable quantum spin chains. We use this
approach to calculate the breather boundary S matrix for the open XXZ spin
chain with diagonal boundary fields. We also compute the soliton boundary S
matrix in the critical regime.Comment: 23 pages, LaTeX, 1 eps figur
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