92 research outputs found
Area Distribution of Elastic Brownian Motion
We calculate the excursion and meander area distributions of the elastic
Brownian motion by using the self adjoint extension of the Hamiltonian of the
free quantum particle on the half line. We also give some comments on the area
of the Brownian motion bridge on the real line with the origin removed. We will
stress on the power of self adjoint extension to investigate different possible
boundary conditions for the stochastic processes.Comment: 18 pages, published versio
Universal logarithmic correction to Rényi (Shannon) entropy in generic systems of critical quadratic fermions
The R\'enyi (Shannon) entropy, i.e. , of the ground state of
quantum systems in local bases normally show a volume-law behavior. For a
subsystem of quantum chains at critical point there is an extra logarithmic
subleading term with a coefficient which is universal. In this paper we study
this coefficient for generic time-reversal translational invariant quadratic
critical free fermions. These models can be parameterized by a complex function
which has zeros on the unit circle. When the zeros on the unit circle do not
have degeneracy and there is no zero outside of the unit circle we are able to
classify the coefficient of the logarithm. In particular, we numerically
calculate the R\'enyi (Shannon) entropy in configuration basis for wide variety
of these models and show that there are two distinct classes. For systems with
symmetry the coefficient is proportional to the central charge, i.e. one
half of the number of points that one can linearize the dispersion relation of
the system; for all the values of with transition point at .
For systems without this symmetry, when this coefficient is again
proportional to the central charge. However, the coefficient for
is a new universal number. Finally, by using the discrete version of
Bisognano-Wichmann modular Hamiltonian of the Ising chain we show that these
coefficients are universal and dependent on the underlying CFT.Comment: v2: 16 pages, 10 figures published versio
Population abundance of pomegranate aphid, Aphis punicae (Homoptera: Aphididae), predators in Southwest of Iran
Pomegranate aphid, Aphis punicae Passarini (Hom., Aphididae) is an important pest of pomegranate in Iran. Predators play critical role in natural control of the pest. In this study, seasonal population dynamics of the aphid predators were investigated during two years (2016/2017) in Ilam province, southwest of Iran. Samplings were bi-weekly performed in an experimental pomegranate orchard. Four insect predators, Coccinella septempunctata L., Oenopia congelobata L. (Col., Coccinellidae), Xanthogramma pedisseguum Haris (Dip., Syrphidae) and Chrysoperla carnea Stephens (Neu., Chryspidae) were identified as predators of A. punicae in Ilam. The natural enemies occurred during March to May in both years. The highest and the lowest densities were belong to X. pedisseguum and O. congelobata, respectively. Results of the study can be used for developing integrated pest management program of A. punicae in pomegranate orchards
Evaluation of various diets and oviposition substrates for rearing Orius albidipennis Reuter
A suitable diet and oviposition substrate are two basic needs for successful mass rearing of Orius spp. and this may reduce their production costs. The effect of various foods containing eggs of Ephestia kuehniella and Sitotroga cerealella with various pollens were investigated on the biological parameters of O. albidipennis in the laboratory. Moreover, survival, hatching rate and fecundity of the predatory bug on various natural substrates were compared. Nymphal developmental time of the bug on diets including E. kuehniella and S. cerealella varied from 13 to 14.2 and 14 to 15.3 days, respectively. The nymph and adult survival and consumption rate were not significantly affected by the dietary treatments. Because of a more rapid development with food containing eggs of E. kuehniella, they are the best nymphal diets for mass rearing of O. albidipennis. It must be noted that S. cerealella eggs are six times cheaper than E. kuehniella eggs. Therefore, the foods containing eggs of S. cerealella may be more economic for mass rearing of the bug despite a slower development of nymphs that fed on them. Also, composition of S. cerealella and date palm pollen is the most suitable diet for mass rearing of O. albidipennis adults due to a higher fecundity and longevity of the adults and lower costs of the diet. Female longevity, total eggs and hatching percentage of the predatory bug on Sedum ternatum were significantly higher than other natural substrates. These results may have practical implications for mass rearing of O. albidipennis as part of a biological control program
Explicit Renormalization Group for D=2 random bond Ising model with long-range correlated disorder
We investigate the explicit renormalization group for fermionic field
theoretic representation of two-dimensional random bond Ising model with
long-range correlated disorder. We show that a new fixed point appears by
introducing a long-range correlated disorder. Such as the one has been observed
in previous works for the bosonic () description. We have calculated
the correlation length exponent and the anomalous scaling dimension of
fermionic fields at this fixed point. Our results are in agreement with the
extended Harris criterion derived by Weinrib and Halperin.Comment: 5 page
Area distribution and the average shape of a L\'evy bridge
We consider a one dimensional L\'evy bridge x_B of length n and index 0 <
\alpha < 2, i.e. a L\'evy random walk constrained to start and end at the
origin after n time steps, x_B(0) = x_B(n)=0. We compute the distribution
P_B(A,n) of the area A = \sum_{m=1}^n x_B(m) under such a L\'evy bridge and
show that, for large n, it has the scaling form P_B(A,n) \sim n^{-1-1/\alpha}
F_\alpha(A/n^{1+1/\alpha}), with the asymptotic behavior F_\alpha(Y) \sim
Y^{-2(1+\alpha)} for large Y. For \alpha=1, we obtain an explicit expression of
F_1(Y) in terms of elementary functions. We also compute the average profile <
\tilde x_B (m) > at time m of a L\'evy bridge with fixed area A. For large n
and large m and A, one finds the scaling form = n^{1/\alpha}
H_\alpha({m}/{n},{A}/{n^{1+1/\alpha}}), where at variance with Brownian bridge,
H_\alpha(X,Y) is a non trivial function of the rescaled time m/n and rescaled
area Y = A/n^{1+1/\alpha}. Our analytical results are verified by numerical
simulations.Comment: 21 pages, 4 Figure
Integrability as a consequence of discrete holomorphicity: the Z_N model
It has recently been established that imposing the condition of discrete
holomorphicity on a lattice parafermionic observable leads to the critical
Boltzmann weights in a number of lattice models. Remarkably, the solutions of
these linear equations also solve the Yang-Baxter equations. We extend this
analysis for the Z_N model by explicitly considering the condition of discrete
holomorphicity on two and three adjacent rhombi. For two rhombi this leads to a
quadratic equation in the Boltzmann weights and for three rhombi a cubic
equation. The two-rhombus equation implies the inversion relations. The
star-triangle relation follows from the three-rhombus equation. We also show
that these weights are self-dual as a consequence of discrete holomorphicity.Comment: 11 pages, 7 figures, some clarifications and a reference adde
Bessel Process and Conformal Quantum Mechanics
Different aspects of the connection between the Bessel process and the
conformal quantum mechanics (CQM) are discussed. The meaning of the possible
generalizations of both models is investigated with respect to the other model,
including self adjoint extension of the CQM. Some other generalizations such as
the Bessel process in the wide sense and radial Ornstein- Uhlenbeck process are
discussed with respect to the underlying conformal group structure.Comment: 28 Page
Positivity, entanglement entropy, and minimal surfaces
The path integral representation for the Renyi entanglement entropies of
integer index n implies these information measures define operator correlation
functions in QFT. We analyze whether the limit , corresponding
to the entanglement entropy, can also be represented in terms of a path
integral with insertions on the region's boundary, at first order in .
This conjecture has been used in the literature in several occasions, and
specially in an attempt to prove the Ryu-Takayanagi holographic entanglement
entropy formula. We show it leads to conditional positivity of the entropy
correlation matrices, which is equivalent to an infinite series of polynomial
inequalities for the entropies in QFT or the areas of minimal surfaces
representing the entanglement entropy in the AdS-CFT context. We check these
inequalities in several examples. No counterexample is found in the few known
exact results for the entanglement entropy in QFT. The inequalities are also
remarkable satisfied for several classes of minimal surfaces but we find
counterexamples corresponding to more complicated geometries. We develop some
analytic tools to test the inequalities, and as a byproduct, we show that
positivity for the correlation functions is a local property when supplemented
with analyticity. We also review general aspects of positivity for large N
theories and Wilson loops in AdS-CFT.Comment: 36 pages, 10 figures. Changes in presentation and discussion of
Wilson loops. Conclusions regarding entanglement entropy unchange
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