77 research outputs found
Deformed integrable σ-models, classical R-matrices and classical exchange algebra on Drinfel’d doubles
We describe a unifying framework for the systematic construction of integrable deformations of integrable σ-models within the Hamiltonian formalism. It applies equally to both the 'Yang–Baxter' type as well as 'gauged WZW' type deformations which were considered recently in the literature. As a byproduct, these two families of integrable deformations are shown to be Poisson–Lie T-dual of one anotherPeer reviewedFinal Accepted Versio
Scale invariance of the eta-deformed AdS5 x S5 superstring, T-duality and modified type II equations
We consider the ABF background underlying the eta-deformed AdS5 x S5 sigma
model. This background fails to satisfy the standard IIB supergravity equations
which indicates that the corresponding sigma model is not Weyl invariant, i.e.
does not define a critical string theory in the usual sense. We argue that the
ABF background should still correspond to UV finite theory on a flat 2d
world-sheet, implying that the eta-deformed model is scale invariant. This
property follows from the formal relation via T-duality between the
eta-deformed model and the one defined by an exact type IIB supergravity
solution that has 6 isometries albeit broken by a linear dilaton. We find that
the ABF background satisfies candidate type IIB scale invariance conditions
which for the R-R field strengths are of the second order in derivatives.
Surprisingly, we also find that the this background obeys an interesting
modification of the standard IIB supergravity equations that are first order in
derivatives of R-R fields. These modified equations explicitly depend on
Killing vectors of the ABF background and, although not universal, imply the
universal scale invariance conditions. Moreover, we show that it is precisely
the non-isometric dilaton of the T-dual solution that leads, after the
T-duality, to a modification of type II equations from their standard form. We
conjecture that the modified equations should follow from kappa-symmetry of the
eta-deformed model. All our observations apply also to eta-deformations of AdS3
x S3 and AdS2 x S2 models.Comment: 40 pages; v2: comments added and typos corrected, 41 page
Beta function of k deformed AdS5 × S 5 string theory
We calculate the one loop beta function for the would-be marginal coupling on
the world sheet of the k deformed sigma models associated to a quantum group
with q=exp(i pi/k). This includes the bosonic principal chiral models and
symmetric space sigma models but also the k deformed semi-symmetric space sigma
model describing strings in a deformation of AdS_5 x S^5. The world sheet sigma
model is a current-current deformation of the gauged WZW model for the
supergroup PSU(2,2|4) with level k. In the string theory context the beta
function is shown to vanish because of the vanishing of the Killing form of
PSU(2,2|4) which is another piece of evidence that the k deformed theories
define consistent string theories.Comment: 26 pages, some typos correcte
Giant magnons of string theory in the lambda background
The analogues of giant magnon configurations are studied on the string world
sheet in the lambda background. This is a discrete deformation of the
AdS(5)xS(5) background that preserves the integrability of the world sheet
theory. Giant magnon solutions are generated using the dressing method and
their dispersion relation is found. This reduces to the usual dyonic giant
magnon dispersion relation in the appropriate limit and becomes relativistic in
another limit where the lambda model becomes the generalized sine-Gordon theory
of the Pohlmeyer reduction. The scattering of giant magnons is then shown in
the semi-classical limit to be described by the quantum S-matrix that is a
quantum group deformation of the conventional giant magnon S-matrix. It is
further shown that in the small g limit, a sector of the S-matrix is related to
the XXZ spin chain whose spectrum matches the spectrum of magnon bound states.Comment: 53 pages, 6 figures, final version to appear in JHE
D-branes in λ-deformations
We show that the geometric interpretation of D-branes in WZW models as twisted conjugacy classes persists in the --deformed theory. We obtain such configurations by demanding that a monodromy matrix constructed from the Lax connection of the --deformed theory continues to produce conserved charges in the presence of boundaries. In this way the D-brane configurations obtained correspond to ``integrable'' boundary configurations. We illustrate this with examples based on and , and comment on the relation of these D-branes to both non-Abelian T-duality and Poisson-Lie T-duality. We show that the D2 supported by D0 charge in the --deformed theory map, under analytic continuation together with Poisson-Lie T-duality, to D3 branes in the -deformation of the principal chiral model
Environmental and genetic influences on early attachment
Attachment theory predicts and subsequent empirical research has amply demonstrated that individual variations in patterns of early attachment behaviour are primarily influenced by differences in sensitive responsiveness of caregivers. However, meta-analyses have shown that parenting behaviour accounts for about one third of the variance in attachment security or disorganisation. The exclusively environmental explanation has been challenged by results demonstrating some, albeit inconclusive, evidence of the effect of infant temperament. In this paper, after reviewing briefly the well-demonstrated familial and wider environmental influences, the evidence is reviewed for genetic and gene-environment interaction effects on developing early attachment relationships. Studies investigating the interaction of genes of monoamine neurotransmission with parenting environment in the course of early relationship development suggest that children's differential susceptibility to the rearing environment depends partly on genetic differences. In addition to the overview of environmental and genetic contributions to infant attachment, and especially to disorganised attachment relevant to mental health issues, the few existing studies of gene-attachment interaction effects on development of childhood behavioural problems are also reviewed. A short account of the most important methodological problems to be overcome in molecular genetic studies of psychological and psychiatric phenotypes is also given. Finally, animal research focusing on brain-structural aspects related to early care and the new, conceptually important direction of studying environmental programming of early development through epigenetic modification of gene functioning is examined in brief
Wellbeing and resilience:Mechanisms of transmission of health and risk in parents with complex mental health problems and their offspring—The WARM Study
The WARM study is a longitudinal cohort study following infants of mothers with schizophrenia, bipolar disorder, depression and control from pregnancy to infant 1 year of age.
Background:
Children of parents diagnosed with complex mental health problems including schizophrenia, bipolar disorder and depression, are at increased risk of developing mental health problems compared to the general population. Little is known regarding the early developmental trajectories of infants who are at ultra-high risk and in particular the balance of risk and protective factors expressed in the quality of early caregiver-interaction.
Methods/Design:
We are establishing a cohort of pregnant women with a lifetime diagnosis of schizophrenia, bipolar disorder, major depressive disorder and a non-psychiatric control group. Factors in the parents, the infant and the social environment will be evaluated at 1, 4, 16 and 52 weeks in terms of evolution of very early indicators of developmental risk and resilience focusing on three possible environmental transmission mechanisms: stress, maternal caregiver representation, and caregiver-infant interaction.
Discussion:
The study will provide data on very early risk developmental status and associated psychosocial risk factors, which will be important for developing targeted preventive interventions for infants of parents with severe mental disorder
Integrable λ-deformations: squashing coset CFTs and AdS5 × S 5
Abstract: We examine integrable λ-deformations of SO(n + 1)/SO(n) coset CFTs and their analytic continuations. We provide an interpretation of the deformation as a squashing of the corresponding coset σ-model’s target space. We realise the λ-deformation for n = 5 case as a solution to supergravity supported by non-vanishing five-form and dilaton. This interpolates between the coset CFT SO(4, 2)/SO(4, 1) × SO(6)/SO(5) constructed as a gauged WZW model and the non-Abelian T-dual of the AdS5 × S5 spacetime. © 2015, The Author(s)
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