15,210 research outputs found
Two-Dimensional Quantum Gravity in Temporal Gauge
We propose a new type of gauge in two-dimensional quantum gravity. We
investigate pure gravity in this gauge, and find that the system reduces to
quantum mechanics of loop length . Furthermore, we rederive the
string field theory which was discovered recently. In particular, the
pregeometric form of the Hamiltonian is naturally reproduced.Comment: 24 pages, 1 uuencoded figure, LaTeX file, YITP/K-1045. (Added
detailed explanation and references.
Analysis of (K^-,K^+) inclusive spectrum with semiclassical distorted wave model
The inclusive K^+ momentum spectrum in the 12C(K^-,K^+) reaction is
calculated by the semiclassical distorted wave (SCDW) model, including the
transition to the \Xi^- bound state. The calculated spectra with the strength
of the \Xi^--nucleus potential -50, -20, and +10 MeV are compared with the
experimental data measured at KEK with p_{K^-}=1.65 GeV/c. The shape of the
spectrum is reproduced by the calculation. Though the inclusive spectrum
changes systematically depending on the potential strength, it is not possible
to obtain a constraint on the potential from the present data. The calculated
spectrum is found to have strong emission-angle dependence. We also investigate
the incident K^- momentum dependence of the spectrum to see the effect of the
Fermi motion of the target nucleons which is explicitly treated in the SCDW
method.Comment: 7 pages, 5 figure
Twisted Elliptic Genera of N=2 SCFTs in Two Dimensions
The elliptic genera of two-dimensional N=2 superconformal field theories can
be twisted by the action of the integral Heisenberg group if their U(1) charges
are fractional. The basic properties of the resulting twisted elliptic genera
and the associated twisted Witten indices are investigated with due attention
to their behaviors in orbifoldization. Our findings are illustrated by and
applied to several concrete examples. We give a better understanding of the
duality phenomenon observed long before for certain Landau-Ginzburg models. We
revisit and prove an old conjecture of Witten which states that every ADE
Landau-Ginzburg model and the corresponding minimal model share the same
elliptic genus. Mathematically, we establish ADE generalizations of the
quintuple product identity.Comment: 28 pages; v2 refs adde
String Field Theory from IIB Matrix Model
We derive Schwinger-Dyson equations for the Wilson loops of a type IIB matrix
model. Superstring coordinates are introduced through the construction of the
loop space. We show that the continuum limit of the loop equation reproduces
the light-cone superstring field theory of type IIB superstring in the large-N
limit. We find that the interacting string theory can be obtained in the double
scaling limit as it is expected.Comment: 21 pages, Latex, 1 figur
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Neural Representations of Courtship Song in the Drosophila Brain
Acoustic communication in drosophilid flies is based on the production and perception of courtship songs, which facilitate mating. Despite decades of research on courtship songs and behavior in Drosophila, central auditory responses have remained uncharacterized. In this study, we report on intracellular recordings from central neurons that innervate the Drosophila antennal mechanosensory and motor center (AMMC), the first relay for auditory information in the fly brain. These neurons produce graded-potential (nonspiking) responses to sound; we compare recordings from AMMC neurons to extracellular recordings of the receptor neuron population [Johnston's organ neurons (JONs)]. We discover that, while steady-state response profiles for tonal and broadband stimuli are significantly transformed between the JON population in the antenna and AMMC neurons in the brain, transient responses to pulses present in natural stimuli (courtship song) are not. For pulse stimuli in particular, AMMC neurons simply low-pass filter the receptor population response, thus preserving low-frequency temporal features (such as the spacing of song pulses) for analysis by postsynaptic neurons. We also compare responses in two closely related Drosophila species, Drosophila melanogaster and Drosophila simulans, and find that pulse song responses are largely similar, despite differences in the spectral content of their songs. Our recordings inform how downstream circuits may read out behaviorally relevant information from central neurons in the AMMC
Poincar\'{e} gauge theory of gravity
A Poincar\'{e} gauge theory of (2+1)-dimensional gravity is developed.
Fundamental gravitational field variables are dreibein fields and Lorentz gauge
potentials, and the theory is underlain with the Riemann-Cartan space-time. The
most general gravitational Lagrangian density, which is at most quadratic in
curvature and torsion tensors and invariant under local Lorentz transformations
and under general coordinate transformations, is given. Gravitational field
equations are studied in detail, and solutions of the equations for weak
gravitational fields are examined for the case with a static, \lq \lq spin"less
point like source. We find, among other things, the following: (1)Solutions of
the vacuum Einstein equation satisfy gravitational field equations in the
vacuum in this theory. (2)For a class of the parameters in the gravitational
Lagrangian density, the torsion is \lq \lq frozen" at the place where \lq \lq
spin" density of the source field is not vanishing. In this case, the field
equation actually agrees with the Einstein equation, when the source field is
\lq \lq spin"less. (3)A teleparallel theory developed in a previous paper is
\lq \lq included as a solution" in a limiting case. (4)A Newtonian limit is
obtainable, if the parameters in the Lagrangian density satisfy certain
conditions.Comment: 27pages, RevTeX, OCU-PHYS-15
Heisenberg and Modular Invariance of N=2 Conformal Field Theory
We present a theta function representation of the twisted characters for the
rational N=2 superconformal field theory, and discuss the Jacobi-form like
functional properties of these characters for a fixed central charge under the
action of a finite Heisenberg group and modular transformations.Comment: 21 pages, Latex, 1 figure; minor typos corrected--Journal versio
The Boundary Conformal Field Theories of the 2D Ising critical points
We present a new method to identify the Boundary Conformal Field Theories
(BCFTs) describing the critical points of the Ising model on the strip. It
consists in measuring the low-lying excitation energies spectra of its quantum
spin chain for different boundary conditions and then to compare them with
those of the different boundary conformal field theories of the
minimal model.Comment: 7 pages, no figures. Talk given at the XXth International Conference
on Integrable Systems and Quantum Symmetries (ISQS-20). Prague, June 201
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