75 research outputs found
The Heterotic Dyonic Instanton
The static Yang-Mills-Higgs dyonic instanton is shown to have a
non-vanishing, but anti-self-dual, angular momentum 2-form with skew
eigenvalues equal to the electric charge; for large charge the angular momentum
causes the instanton to expand into a hyper-spherical shell. A class of exact
multi dyonic instantons is then found and then generalized to a new class of
1/4 supersymmetric, non-singular, stationary, exact solutions of the
ten-dimensional supergravity/Yang-Mills theory. These self-gravitating dyonic
instantons yield new heterotic string solitons, to leading order in the inverse
string tension.Comment: 18 pages, LaTeX, no figures. Previous revision was to include exact
multi-solitons. Third version corrects typos and ADM energy formul
Stringy effects for spinning strings and the Bethe ansatz
The one-loop worldsheet corrections to spinning strings in the sl(2) subsector of AdS5 Ă S5 are compared to the quantum string Bethe ansatz. The evaluation of the energy shift is performed in two regimes: a) in the large limit, using zeta-function regularization and b) in the limit of large winding number. The first computation agrees with the Bethe ansatz in the first three orders while the second computation leads to a disagreement with the string Bethe ansatz prediction at leading order. Careful analysis of the zeta-function regularization shows, that in this approach perturbative as well as non-perturbative terms in the string sums are missed. Hence, this together with the result b), implies that the proposed quantum string Bethe equations do not reproduce all terms in the exact string result
Phases of kinky holographic nuclear matter
Holographic QCD at finite baryon number density and zero temperature is studied within the five-dimensional Sakai-Sugimoto model. We introduce a new approximation that models a smeared crystal of solitonic baryons by assuming spatial homogeneity to obtain an effective kink theory in the holographic direction. The kink theory correctly reproduces a first order phase transition to lightly bound nuclear matter. As the density is further increased the kink splits into a pair of half-kink constituents, providing a concrete realization of the previously suggested dyonic salt phase, where the bulk soliton splits into constituents at high density. The kink model also captures the phenomenon of baryonic popcorn, in which a first order phase transition generates an additional soliton layer in the holographic direction. We find that this popcorn transition takes place at a density below the dyonic salt phase, making the latter energetically unfavourable. However, the kink model predicts only one pop, rather than the sequence of pops suggested by previous approximations. In the kink model the two layers produced by the single pop form the surface of a soliton bag that increases in size as the baryon chemical potential is increased. The interior of the bag is filled with abelian electric potential and the instanton charge density is localized on the surface of the bag. The soliton bag may provide a holographic description of a quarkyonic phase
Linking BĂ€cklund and monodromy charges for strings on AdS<sub>5</sub> x S<sup>5</sup>
We find an explicit relation between the two known ways of generating an infinite set of local conserved charges for the string sigma model on AdS5 Ă S5: the BĂ€cklund and monodromy approaches. We start by constructing the two-parameter family of BĂ€cklund transformations for the string with an arbitrary world-sheet metric. We then show that only for a special value of one of the parameters the solutions generated by this transformation are compatible with the Virasoro constraints. By solving the BĂ€cklund equations in a non-perturbative fashion, we finally show that the generating functional of the BĂ€cklund conservation laws is equal to a certain sum of the quasi-momenta. The positions of the quasi-momenta in the complex spectral plane are uniquely determined by the real parameter of the BĂ€cklund transform
Geometry of the Nonabelian DBI Dyonic Instanton
We introduce a calculus of the Lie algebra valued functions present in
Tseytlin's proposal for the nonabelian DBI action, and apply it to show that
the recently found dyonic instanton is a solution of the full nonabelian DBI
action. The geometry of this solution exhibits a new effect of ``blowing-up''
of the brane, which was not present in the case of the brane realisation of
monopoles. We interpret this solution as the superposition of the D0 brane and
fundamental string F1 which connects two separated D4 branes. Both F1 and D0
are delocalised in the ``blown-up'' region between two separated D4 branes.Comment: 14 pages, 3 figures; v2: minor changes and added reference
Finite energy Dirac-Born-Infeld monopoles and string junctions
It is shown that the world volume field theory of a single D3-brane in a supergravity D3-brane background admits finite energy, and non-singular, Abelian monopoles and dyons preserving 1/2 or 1/4 of the N=4 supersymmetry and saturating a Bogomolnyi-type bound. The 1/4 supersymmetric solitons provide a world volume realization of string-junction dyons. We also discuss the dual M-theory realization of the 1/2 supersymmetric dyons as finite tension self-dual strings on the M5-brane, and of the 1/4 supersymmetric dyons as their intersections
On the maximal superalgebras of supersymmetric backgrounds
In this note we give a precise definition of the notion of a maximal
superalgebra of certain types of supersymmetric supergravity backgrounds,
including the Freund-Rubin backgrounds, and propose a geometric construction
extending the well-known construction of its Killing superalgebra. We determine
the structure of maximal Lie superalgebras and show that there is a finite
number of isomorphism classes, all related via contractions from an
orthosymplectic Lie superalgebra. We use the structure theory to show that
maximally supersymmetric waves do not possess such a maximal superalgebra, but
that the maximally supersymmetric Freund-Rubin backgrounds do. We perform the
explicit geometric construction of the maximal superalgebra of AdS_4 x S^7 and
find that is isomorphic to osp(1|32). We propose an algebraic construction of
the maximal superalgebra of any background asymptotic to AdS_4 x S^7 and we
test this proposal by computing the maximal superalgebra of the M2-brane in its
two maximally supersymmetric limits, finding agreement.Comment: 17 page
Coordinate Bethe Ansatz for the String S-Matrix
We use the coordinate Bethe ansatz approach to derive the nested Bethe
equations corresponding to the recently found S-matrix for strings in AdS5 x
S5, compatible with centrally extended su(2|2) symmetry.Comment: 25 Pages, plain LaTeX, 4 Figures. Mostly added references, fixed
typo
Tachyon condensation on brane sphalerons
We consider a sphaleron solution in field theory that provides a toy model
for unstable D-branes of string theory. We investigate the tachyon condensation
on a Dp-brane. The localized modes, including a tachyon, arise in the spectrum
of a sphaleron solution of a \phi^4 field theory on M^{p+1}\times S^1. We use
these modes to find a multiscalar tachyon potential living on the sphaleron
world-volume. A complete cancelation between brane tension and the minimum of
the tachyon potential is found as the size of the circle becomes small.Comment: To appear in JHEP, 13 pages, 2 eps figures, minor changes and
references adde
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