2,667 research outputs found
Small Landau-Ginzburg theories
We classify (0,2) Landau-Ginzburg theories that can flow to compact IR fixed
points with equal left and right central charges strictly bounded by 3. Our
result is a (0,2) generalization of the ADE classification of (2,2)
Landau-Ginzburg theories that flow to N=2 minimal models. Unitarity requires
the right-moving supersymmetric sector to fall into the standard N=2 minimal
model representations, but the left-moving sector need not have supersymmetry.
The Landau-Ginzburg realizations provide a simple way to compute the chiral
algebra and other characteristics of these fixed points. While our results
pertain to isolated superconformal theories, tensor products lead to (0,2)
superconformal theories with higher central charge, and the Landau-Ginzburg
realization provides a model for a class of marginal and relevant deformations
of such theories.Comment: 22 pages; typos fixed, added discussion on chiral algebr
Two-loop planar master integrals for the production of off-shell vector bosons in hadron collisions
We describe the calculation of all planar master integrals that are needed
for the computation of NNLO QCD corrections to the production of two off-shell
vector bosons in hadron collisions. The most complicated representatives of
integrals in this class are the two-loop four-point functions where two
external lines are on the light-cone and two other external lines have
different invariant masses. We compute these and other relevant integrals
analytically using differential equations in external kinematic variables and
express our results in terms of Goncharov polylogarithms. The case of two equal
off-shellnesses, recently considered in Ref. [1], appears as a particular case
of our general solution.Comment: 28 pages, many figures; ancillary files included with arXiv
submissio
Supersymmetric Boundary Conditions for the N=2 Sigma Model
We clarify the discussion of N=2 supersymmetric boundary conditions for the
classical d=2, N=(2,2) Non-Linear Sigma Model on an infinite strip. Our
conclusions about the supersymmetric cycles match the results found in the
literature. However, we find a constraint on the boundary action that is not
satisfied by many boundary actions used in the literature.Comment: 23 pages, no figures. minor changes in text, a reference adde
Accidents in (0,2) Landau-Ginzburg theories
We study the role of accidental symmetries in two-dimensional (0,2)
superconformal field theories obtained by RG flow from (0,2) Landau-Ginzburg
theories. These accidental symmetries are ubiquitous, and, unlike in the case
of (2,2) theories, their identification is key to correctly identifying the IR
fixed point and its properties. We develop a number of tools that help to
identify such accidental symmetries in the context of (0,2) Landau-Ginzburg
models and provide a conjecture for a toric structure of the SCFT moduli space
in a large class of models. We also give a self-contained discussion of aspects
of (0,2) conformal perturbation theory.Comment: 37 pages; expanded conformal perturbation theory discussion in v2;
fixed an accident in section 3.5 in v
Modulation of gyrosynchrotron emission in solar and stellar flares by slow magnetoacoustic oscillations
Gyrosynchrotron emission generated by non-thermal electrons in solar and stellar coronal flares can be efficiently modulated by slow magnetoacoustic oscillations in the flaring loops. The modulation mechanism is based upon perturbation of the efficiency in the Razin suppression of optically thin gyrosynchrotron emission. Modulation of the emission is in anti-phase with the density perturbation in the slow wave. The observed emission modulation depth can be up to an order of magnitude higher than the slow wave amplitude. This effect is more pronounced at lower frequencies. Observations with spatial resolution, together with analysis of the modulation frequency, are shown to be sufficient for providing the information needed to identify the mode
- …