Black hole scattering from monodromy Castro, Alejandra; Lapan, Joshua M; Maloney, Alexander ...
Classical and quantum gravity,
08/2013, Letnik:
30, Številka:
16
Journal Article
Recenzirano
Odprti dostop
We study scattering coefficients in black hole spacetimes using analytic properties of complexified wave equations. For a concrete example, we analyse the singularities of the Teukolsky equation and ...relate the corresponding monodromies to scattering data. These techniques, valid in full generality, provide insights into complex-analytic properties of greybody factors and quasinormal modes. This leads to new perturbative and numerical methods which are in good agreement with previous results.
A
bstract
The two-dimensional supersymmetric gauged linear sigma model (GLSM) with abelian gauge groups and matter fields has provided many insights into string theory on Calabi-Yau manifolds of a ...certain type: complete intersections in toric varieties. In this paper, we consider two GLSM constructions with nonabelian gauge groups and charged matter whose infrared CFTs correspond to string propagation on determinantal Calabi-Yau varieties, furnishing another broad class of Calabi-Yau geometries in addition to complete intersections. We show that these two models — which we refer to as the PAX and the PAXY model — are dual descriptions of the same low-energy physics. Using GLSM techniques, we determine the quantum Kähler moduli space of these varieties and find no disagreement with existing results in the literature.
A quantum system will stay near its instantaneous ground state if the Hamiltonian that governs its evolution varies slowly enough. This quantum adiabatic behavior is the basis of a new class of ...algorithms for quantum computing. We tested one such algorithm by applying it to randomly generated hard instances of an NP-complete problem. For the small examples that we could simulate, the quantum adiabatic algorithm worked well, providing evidence that quantum computers (if large ones can be built) may be able to outperform ordinary computers on hard sets of instances of NP-complete problems.
Many
N
=
(
2
,
2
)
two-dimensional nonlinear sigma models with Calabi–Yau target spaces admit ultraviolet descriptions as
N
=
(
2
,
2
)
gauge theories (gauged linear sigma models). We conjecture that ...the two-sphere partition function of such ultraviolet gauge theories—recently computed via localization by Benini et al. and Doroud et al.—yields the exact Kähler potential on the quantum Kähler moduli space for Calabi–Yau threefold target spaces. In particular, this allows one to compute the genus zero Gromov–Witten invariants for any such Calabi–Yau threefold without the use of mirror symmetry. More generally, when the infrared superconformal fixed point is used to compactify string theory, this provides a direct method to compute the spacetime Kähler potential of certain moduli (e.g., vector multiplet moduli in type IIA), exactly in α′. We compute these quantities for the quintic and for Rødland’s Pfaffian Calabi–Yau threefold and find agreement with existing results in the literature. We then apply our methods to a codimension four determinantal Calabi–Yau threefold in
P
7
, recently given a nonabelian gauge theory description by the present authors, for which no mirror Calabi–Yau is currently known. We derive predictions for its Gromov–Witten invariants and verify that our predictions satisfy nontrivial geometric checks.
We investigate aspects of holographic duals to time-like warped
AdS
3
space-times — which include Gödel’s universe — in string theory. Using worldsheet techniques similar to those that have been ...applied to
AdS
3
backgrounds, we are able to identify space-time symmetry algebras that act on the dual boundary theory. In particular, we always find at least one Virasoro algebra with computable central charge. Interestingly, there exists a dense set of points in the moduli space of these models in which there is actually a second commuting Virasoro algebra, typically with different central charge than the first. We analyze the supersymmetry of the backgrounds, finding related enhancements, and comment on possible interpretations of these results. We also perform an asymptotic symmetry analysis at the level of supergravity, providing additional support for the world sheet analysis.
Perturbative Corrections to Kähler Moduli Spaces Halverson, James; Jockers, Hans; Lapan, Joshua M. ...
Communications in mathematical physics,
02/2015, Letnik:
333, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We propose a general formula for perturbative-in-α′ corrections to the Kähler potential on the quantum Kähler moduli space of Calabi–Yau
n
-folds, for any
n
, in their asymptotic large volume regime. ...The knowledge of such perturbative corrections provides an important ingredient needed to analyze the full structure of this Kähler potential, including nonperturbative corrections such as the Gromov–Witten invariants of the Calabi–Yau
n
-folds. We argue that the perturbative corrections take a universal form, and we find that this form is encapsulated in a specific additive characteristic class of the Calabi–Yau
n
-fold which we call the log Gamma class, and which arises naturally in a generalization of Mukai’s modified Chern character map. Our proposal is inspired heavily by the recent observation of an equality between the partition function of certain supersymmetric, two-dimensional gauge theories on a two-sphere, and the aforementioned Kähler potential. We further strengthen our proposal by comparing our findings on the quantum Kähler moduli space to the complex structure moduli space of the corresponding mirror Calabi–Yau geometry.
We compute the massless spectra of a set of flux vacua of the heterotic string. The vacua we study include well-known non-Kähler
T
2
-fibrations over
K
3 with SU(3) structure and intrinsic torsion. ...Following gauged linear sigma models of these vacua into phases governed by asymmetric Landau-Ginzburg orbifolds allows us to compute the spectrum using generalizations of familiar LG-orbifold techniques. We study several four- and six-dimensional examples with spacetime
supersymmetry in detail.
Linear Models for Flux Vacua Adams, Allan; Ernebjerg, Morten; Lapan, Joshua M.
Advances in theoretical and mathematical physics,
2008, Letnik:
12, Številka:
4
Journal Article
A
bstract
We discuss a marginal deformation of the SL(2, R) × SU(2) × U(1)
4
WZW model, which describes string theory on AdS3 × S
3
× T
4
, that corresponds to warping the S
3
factor. This ...deformation breaks part of the
= (4, 4) supersymmetry of the undeformed dual CFT to
= (0, 4) supersymmetry. In the spirit of work by Giveon, Kutasov, and Seiberg, we construct the asymptotic spacetime symmetry algebra from worldsheet operators and find a restoration of (4, 4) supersymmetry at discrete values of the deformation parameter. We explain this result from various perspectives: the worldsheet, supergravity, and from the singular D1-D5 CFT. The supergravity analysis includes an asymptotic symmetry computation of the level of the affine SU(2) R-symmetry, which arises purely from B-field contributions.
Fu and Yau constructed the first smooth family of gauge bundles over a class of non-Kähler, complex 3-folds that are solutions to Strominger’s system, the heterotic supersymmetry constraints with ...non-zero H-flux. In this paper, we begin the study of the massless spectrum arising from compactification using this construction by counting zero modes of the
linearized equations of motion for the gaugino in the supergravity approximation. We rephrase the question in terms of a cohomology problem and show that for a trivial gauge bundle, this cohomology reduces to the Dolbeault cohomology of the 3-fold, which we then compute.
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