arXiv subjects

Julian Lee

Publications and source records attributed to Julian Lee.

42 records · Page 3Linked to original sources

arXiv1995

Stability Analysis of the Dilatonic Black Hole in Two Dimensions

We explicitly show that the net number of degrees of freedom in the two-dimensional dilaton gravity is zero through the Hamiltonian constraint analysis. This implies that the local space-time dependent physical excitations do not exist. From the linear perturbation around the black hole background, we explicitly prove that the exponentially growing mode with time is in fact eliminated outside the horizon. Therefore, the two-dimensional dilation gravity is essentially stable.

hep-th↗

arXiv1995

Hawking Radiation and Energy Conservation in an Evaporating Black Hole

We define the Bondi energy for two-dimensional dilatonic gravity theories by generalizing the known expression of the ADM energy. We show that our definition of the Bondi energy is exactly the ADM energy minus the radiation energy at null infinity. An explicit calculation is done for the evaporating black hole in the RST model with the Strominger's ghost decoupling term. It is shown that the infalling matter energy is completely recovered through the Hawking radiation and the thunderpop.

hep-th↗

arXiv1995

ADM, Bondi mass, and energy conservation in two-dimensional dilaton gravities

We show how a stress-energy pseudotensor can be constructed in two-dimensional dilatonic gravity theories (classical, CGHS and RST) and derive the expression for the ADM mass in these theories from it. We define the Bondi mass for these theories by using the pseudotensor formalism. The resulting expression is the generalization of the expression for the ADM mass. The boundary condition needed for the energy conservation is also investigated. It is shown that under appropriate boundary conditions, our definition of the Bondi mass is exactly the ADM mass minus the matter radiation energy at null infinity.

hep-th↗

arXiv1994

Perturbative Calculations in the Effective Lagrangian and $2D$ Closed String Field Theory

This paper is devoted to the study of closed string field theory in two dimensions. We compare two different approaches: BRST closed string field theory and the string effective Lagrangian. We show that the quadratic action and the pole structures of tree-level scattering amplitudes agree. We study merits and drawbacks of various gauge fixing procedures. In particular, we discuss conformal gauge in the context of the effective Lagrangian, and Siegel and Lorentz-like gauge in the general BRST approach. We discuss the ways in which discrete states survive a particular gauge fixing both by directly solving the equations of motion, and by analyzing pole structure of the scattering amplitudes.

hep-th↗

arXiv1993

Time-Dependent Backgrounds in 2D String Theory and the $S$-matrix Generating Functional

We study the time-dependent tachyon backgrounds of the string collective field theory using the formalism of the $S$-matrix generating functional. In the process we clarify the connection between two ways of calculating the $S$-matrix, the one using the Feynman rule and the other using the classical solution to the nonlinear equation of motion. We develop the formalism for general backgrounds and apply it to the gravitational sine-Gordon model in detail. We reproduce the conformal field theory calculation which was based on expanding around the static $c=1$ theory. Furthermore, we prove that the tree- level partition function of this model shows the scaling behavior corresponding to $c=0$ model in the limit $p \to 0$ of sine-Gordon `momentum' $p$.

hep-th↗

arXiv1992

Semiclassical Tunneling in 1+1 Dimensional String Theory

We describe time-dependent tunneling of massless particles in 1+1 dimensional string field theory. Polchinski's description of the classical solutions in terms of the Fermi sea is used to identify the leading instanton contribution connecting the two half-lines. The field theory lagrangian is proportional to $1/g^2$, where $g$ is the string coupling constant, but the $S$-matrix for tunneling from one half-line to the other behaves as $\exp(-C/g)$. We note the constant~$C$ involves curious boundary contributions and observe that a prescription connecting the two half-lines unifies treatments of the Fermi level above and below the barrier. We also note the relation to recent work of Brustein and Ovrut.

hep-th↗