79,719 research outputs found
Tentative Detection of Deuterated Methane toward the Low-Mass Protostar IRAS 04368+2557 in L1527
The millimeter-wave rotational transition line () of
deuterated methane CHD has tentatively been detected toward the low-mass
Class 0 protostar IRAS 04368+2557 in L1527 with the Heinrich Hertz
Submillimeter Telescope. This is the first detection of CHD in interstellar
clouds, if confirmed. The column density and fractional abundance of CHD
are determined to be cm and , respectively, where we assume the rotational temperature of 25
K. The column density and fractional abundance of the gaseous CH are
estimated to be cm and , respectively, by adopting the molecular D/H ratios of 2--7% reported
for various molecules in L1527. The fractional abundance of CH is higher
than or comparable to that found in high-mass star-forming cores by infrared
observations. It is sufficiently high for triggering the efficient production
of various carbon-chain molecules in a lukewarm region near the protostar,
which supports the picture of the warm carbon-chain chemistry.Comment: 13 page
Lace expansion for the Ising model
The lace expansion has been a powerful tool for investigating mean-field
behavior for various stochastic-geometrical models, such as self-avoiding walk
and percolation, above their respective upper-critical dimension. In this
paper, we prove the lace expansion for the Ising model that is valid for any
spin-spin coupling. For the ferromagnetic case, we also prove that the
expansion coefficients obey certain diagrammatic bounds that are similar to the
diagrammatic bounds on the lace-expansion coefficients for self-avoiding walk.
As a result, we obtain Gaussian asymptotics of the critical two-point function
for the nearest-neighbor model with d>>4 and for the spread-out model with d>4
and L>>1, without assuming reflection positivity.Comment: 54 pages, 12 figure
A note on higher spin symmetry in the IIB matrix model with the operator interpretation
We study the IIB matrix model in an interpretation where the matrices are
differential operators defined on curved spacetimes. In this interpretation,
coefficients of higher derivative operators formally appear to be massless
higher spin fields. In this paper, we examine whether the unitary symmetry of
the matrices includes appropriate higher spin gauge symmetries. We focus on
fields that are bosonic and relatively simple in the viewpoint of the
representation of Lorentz group. We find that the additional auxiliary fields
need to be introduced in order to see the higher spin gauge symmetries
explicitly. At the same time, we point out that a part of these extra fields
are gauged-away, and the rest of part can be written in terms of a totally
symmetric tensor field. The transformation to remove its longitudinal
components exists as well. As a result, we observe that the independent
physical DoF are the transverse components of that symmetric field, and that
the theory describes the corresponding higher spin field. We also find that the
field is not the Fronsdal field, rather the generalization of curvature.Comment: 1+14 pages, 1 figure; discussion on EOM added, Version to appear in
NPB (v2
Topological string amplitudes for the local half K3 surface
We study topological string amplitudes for the local half K3 surface. We
develop a method of computing higher-genus amplitudes along the lines of the
direct integration formalism, making full use of the Seiberg-Witten curve
expressed in terms of modular forms and E_8-invariant Jacobi forms. The
Seiberg-Witten curve was constructed previously for the low-energy effective
theory of the non-critical E-string theory in R^4 x T^2. We clarify how the
amplitudes are written as polynomials in a finite number of generators
expressed in terms of the Seiberg-Witten curve. We determine the coefficients
of the polynomials by solving the holomorphic anomaly equation and the gap
condition, and construct the amplitudes explicitly up to genus three. The
results encompass topological string amplitudes for all local del Pezzo
surfaces.Comment: 35 pages, v2: several clarifications made, an equation and references
added, v3: published versio
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