arXiv subjects

Marina Shmakova

Publications and source records attributed to Marina Shmakova.

24 records · Page 2Linked to original sources

arXiv2000

Excision of Singularities by Stringy Domain Walls

We study supersymmetric domain walls on S_1/Z_2 orbifolds. The supergravity solutions in the bulk are given by the attractor equation associated with Calabi-Yau spaces and have a naked space-time singularity at some |y_s|. We are looking for possibilities to cut off this singularity with the second wall by a stringy mechanism. We use the collapse of the CY cycle at |y_c| which happens before and at a finite distance from the space-time singularity. In our example with three Kahler moduli the second wall is at the end of the moduli space at |y_c| where also the enhancement of SU(2) gauge symmetry takes place so that |y_e|=|y_c|< |y_s|. The physics of the excision of a naked singularity via the enhancon in the context of domain wall has an interpretation on the heterotic side related to R -> 1/R duality. The position of the enhancon is given by the equation R(|y_e|)=1.

hep-th↗

arXiv1999

Supersymmetric Multiple Basin Attractors

We explain that supersymmetric attractors in general have several critical points due to the algebraic nature of the stabilization equations. We show that the critical values of the cosmological constant of the adS_5 vacua are given by the topological (moduli independent) formulae analogous to the entropy of the d=5 supersymmetric black holes. We present conditions under which more than one critical point is available (for black hole entropy as well as to the cosmological constant) so that the system tends to its own locally stable attractor point. We have found several families of Z_2-symmetric critical points where the central charge has equal absolute values but opposite signs in two attractor points. We present examples of interpolating solutions and discuss their generic features.

hep-th↗

arXiv1999

One-loop corrections to the D3 brane action

We calculate one-loop corrections to the effective Lagrangian for the D3 brane. We perform the gauge-fixing of the kappa-symmetric Born-Infeld D3 brane action in the flat background using Killing gauge. The linearized supersymmetry of the gauge-fixed action coincides with that of the N=4 Yang-Mills theory. We use the helicity amplitude and unitarity technique to calculate the one-loop amplitudes at order alpha^4. The counterterms and the finite 1-loop corrections are of the form (dF)^4 and their supersymmetric generalization. This is to be contrasted with the Born-Infeld action which contains (F)^4 and other terms which do not depend on derivatives of the vector field strength.

hep-th↗

arXiv1996

Calabi-Yau Black Holes

We have found the entropy of N=2 extreme black holes associated with general Calabi-Yau moduli space. We show that for arbitrary d_{ABC} and black hole charges the entropy-area formula depends on combinations of these charges and parameters d_{ABC}. These combinations are the solutions of the simple system of algebraic equations. We gave a few examples of particular Calabi-Yau moduli space for which this system has an explicit solution. For special case when one of black hole charges is equal to zero (p^0=0) the solution always exists.

hep-th↗

arXiv1996

Freezing of Moduli by N=2 Dyons

In N=2 ungauged supergravity we have found the most general double-extreme dyonic black holes with arbitrary number n_v of constant vector multiplets and n_h of constant hypermultiplets. They are double-extreme: 1) supersymmetric with coinciding horizons, 2) the mass for a given set of quantized charges is extremal. The spacetime is of the Reissner-Nordstrom form and the vector multiplet moduli depend on dyon charges. As an example we display n_v complex moduli as functions of 2(n_v+1) electric and magnetic charges in a model related to a classical Calabi-Yau moduli space. A specific case includes the complex S, T, U moduli depending on 4 electric and 4 magnetic charges of 4 U(1) gauge groups.

hep-th↗

arXiv1996

STU Black Holes and String Triality

We find double-extreme black holes associated with the special geometry of the Calabi-Yau moduli space with the prepotential F=STU. The area formula is STU-moduli independent and has ${[SL(2,Z)]}^3$ symmetry in space of charges. The dual version of this theory without prepotential treats the dilaton S asymmetric versus T,U-moduli. We display the dual relation between new (STU) black holes and stringy (S|TU) black holes using particular Sp(8, Z) transformation. The area formula of one theory equals that of the dual theory when expressed in terms of dual charges. We analyse the relation between (STU) black holes to string triality of black holes: (S|TU), (T|US), (U|ST) solutions. In the democratic STU-symmetric version we find that all three S and T and U duality symmetries are non-perturbative and mix electric and magnetic charges.

hep-th↗