33 research outputs found
Twist operators in N=4 beta-deformed theory
In this paper we derive both the leading order finite size corrections for
twist-2 and twist-3 operators and the next-to-leading order finite-size
correction for twist-2 operators in beta-deformed SYM theory. The obtained
results respect the principle of maximum transcendentality as well as
reciprocity. We also find that both wrapping corrections go to zero in the
large spin limit. Moreover, for twist-2 operators we studied the pole structure
and compared it against leading BFKL predictions.Comment: 17 pages; v2: minor changes, references adde
Quantum folded string and integrability: from finite size effects to Konishi dimension
Using the algebraic curve approach we one-loop quantize the folded string
solution for the type IIB superstring in AdS(5)xS(5). We obtain an explicit
result valid for arbitrary values of its Lorentz spin S and R-charge J in terms
of integrals of elliptic functions. Then we consider the limit S ~ J ~ 1 and
derive the leading three coefficients of strong coupling expansion of short
operators. Notably, our result evaluated for the anomalous dimension of the
Konishi state gives 2\lambda^{1/4}-4+2/\lambda^{1/4}. This reproduces correctly
the values predicted numerically in arXiv:0906.4240. Furthermore we compare our
result using some new numerical data from the Y-system for another similar
state. We also revisited some of the large S computations using our methods. In
particular, we derive finite--size corrections to the anomalous dimension of
operators with small J in this limit.Comment: 20 pages, 1 figure; v2: references added, typos corrected; v3: major
improvement of the references; v4: Discussion of short operators is
restricted to the case n=1. This restriction does not affect the main results
of the pape
Integrable Wilson loops
The generalized quark-antiquark potential of N=4 supersymmetric Yang-Mills
theory on S^3 x R calculates the potential between a pair of heavy charged
particles separated by an arbitrary angle on S^3 and also an angle in flavor
space. It can be calculated by a Wilson loop following a prescribed path and
couplings, or after a conformal transformation, by a cusped Wilson loop in flat
space, hence also generalizing the usual concept of the cusp anomalous
dimension. In AdS_5 x S^5 this is calculated by an infinite open string. I
present here an open spin-chain model which calculates the spectrum of
excitations of such open strings. In the dual gauge theory these are cusped
Wilson loops with extra operator insertions at the cusp. The boundaries of the
spin-chain introduce a non-trivial reflection phase and break the bulk symmetry
down to a single copy of psu(2|2). The dependence on the two angles is captured
by the two embeddings of this algebra into \psu(2|2)^2, i.e., by a global
rotation. The exact answer to this problem is conjectured to be given by
solutions to a set of twisted boundary thermodynamic Bethe ansatz integral
equations. In particular the generalized quark-antiquark potential or cusp
anomalous dimension is recovered by calculating the ground state energy of the
minimal length spin-chain, with no sites. It gets contributions only from
virtual particles reflecting off the boundaries. I reproduce from this
calculation some known weak coupling perturtbative results.Comment: 40 pages, 11 figures; v2-some formulas corrected, results unchange
Integrability, spin-chains and the AdS3/CFT2 correspondence
Building on arXiv:0912.1723, in this paper we investigate the AdS3/CFT2
correspondence using integrability techniques. We present an all-loop Bethe
Ansatz (BA) for strings on AdS_3 x S^3 x S^3 x S^1, with symmetry
D(2,1;alpha)^2, valid for all values of alpha. This construction relies on a
novel, alpha-dependent generalisation of the Zhukovsky map. We investigate the
weakly-coupled limit of this BA and of the all-loop BA for strings on AdS_3 x
S^3 x T^4. We construct integrable short-range spin-chains and Hamiltonians
that correspond to these weakly-coupled BAs. The spin-chains are alternating
and homogenous, respectively. The alternating spin-chain can be regarded as
giving some of the first hints about the unknown CFT2 dual to string theory on
AdS_3 x S^3 x S^3 x S^1. We show that, in the alpha to 1 limit, the integrable
structure of the D(2,1;alpha) model is non-singular and keeps track of not just
massive but also massless modes. This provides a way of incorporating massless
modes into the integrability machinery of the AdS3/CFT2 correspondence.Comment: LaTeX, 38 pages. v2: Corrected misprints in section 6.
Bacteriophage-Resistant Mutants in Yersinia pestis: Identification of Phage Receptors and Attenuation for Mice
Background: Bacteriophages specific for Yersinia pestis are routinely used for plague diagnostics and could be an alternative to antibiotics in case of drug-resistant plague. A major concern of bacteriophage therapy is the emergence of phageresistant mutants. The use of phage cocktails can overcome this problem but only if the phages exploit different receptors. Some phage-resistant mutants lose virulence and therefore should not complicate bacteriophage therapy. Methodology/Principal Findings: The purpose of this work was to identify Y. pestis phage receptors using site-directed mutagenesis and trans-complementation and to determine potential attenuation of phage-resistant mutants for mice. Six receptors for eight phages were found in different parts of the lipopolysaccharide (LPS) inner and outer core. The receptor for R phage was localized beyond the LPS core. Most spontaneous and defined phage-resistant mutants of Y. pestis were attenuated, showing increase in LD 50 and time to death. The loss of different LPS core biosynthesis enzymes resulted in the reduction of Y. pestis virulence and there was a correlation between the degree of core truncation and the impact on virulence. The yrbH and waaA mutants completely lost their virulence. Conclusions/Significance: We identified Y. pestis receptors for eight bacteriophages. Nine phages together use at least seven different Y. pestis receptors that makes some of them promising for formulation of plague therapeutic cocktails. Most phage-resistant Y. pestis mutants become attenuated and thus should not pose a serious problem for bacteriophag