The Factorized S-Matrix of CFT/AdS

We argue that the recently discovered integrability in the large-N CFT/AdS system is equivalent to diffractionless scattering of the corresponding hidden elementary excitations. This suggests that, perhaps, the key tool for finding the spectrum of this system is neither the gauge theory's dilatation operator nor the string sigma model's quantum Hamiltonian, but instead the respective factorized S-matrix. To illustrate the idea, we focus on the closed fermionic su(1|1) sector of the N=4 gauge theory. We introduce a new technique, the perturbative asymptotic Bethe ansatz, and use it to extract this sector's three-loop S-matrix from Beisert's involved algebraic work on the three-loop su(2|3) sector. We then show that the current knowledge about semiclassical and near-plane-wave quantum strings in the su(2), su(1|1) and sl(2) sectors of AdS_5 x S^5 is fully consistent with the existence of a factorized S-matrix. Analyzing the available information, we find an intriguing relation between the three associated S-matrices. Assuming that the relation also holds in gauge theory, we derive the three-loop S-matrix of the sl(2) sector even though this sector's dilatation operator is not yet known beyond one loop. The resulting Bethe ansatz reproduces the three-loop anomalous dimensions of twist-two operators recently conjectured by Kotikov, Lipatov, Onishchenko and Velizhanin, whose work is based on a highly complex QCD computation of Moch, Vermaseren and Vogt.Comment: 38 pages, LaTeX, JHEP3.cl

From Gravitons to Giants

We discuss exact quantization of gravitational fluctuations in the half-BPS sector around AdS$_5 \times$S$^5$ background, using the dual super Yang-Mills theory. For this purpose we employ the recently developed techniques for exact bosonization of a finite number $N$ of fermions in terms of $N$ bosonic oscillators. An exact computation of the three-point correlation function of gravitons for finite $N$ shows that they become strongly coupled at sufficiently high energies, with an interaction that grows exponentially in $N$. We show that even at such high energies a description of the bulk physics in terms of weakly interacting particles can be constructed. The single particle states providing such a description are created by our bosonic oscillators or equivalently these are the multi-graviton states corresponding to the so-called Schur polynomials. Both represent single giant graviton states in the bulk. Multi-particle states corresponding to multi-giant gravitons are, however, different, since interactions among our bosons vanish identically, while the Schur polynomials are weakly interacting at high enough energies.Comment: v2-references added, minor changes and typos corrected; 24 pages, latex, 3 epsf figure

On thermodynamics of N=6 superconformal Chern-Simons theory

We study thermodynamics of N=6 superconformal Chern-Simons theory by computing quantum corrections to the free energy. We find that in weakly coupled ABJM theory on R(2) x S(1), the leading correction is non-analytic in the 't Hooft coupling lambda, and is approximately of order lambda^2 log(lambda)^3. The free energy is expressed in terms of the scalar thermal mass m, which is generated by screening effects. We show that this mass vanishes to 1-loop order. We then go on to 2-loop order where we find a finite and positive mass squared m^2. We discuss differences in the calculation between Coulomb and Lorentz gauge. Our results indicate that the free energy is a monotonic function in lambda which interpolates smoothly to the N^(3/2) behaviour at strong coupling.Comment: 29 pages. v2: references added. v3: minor changes, references added, published versio

Being the next of kin of an older person living in a nursing home : an interview study about quality of life.

BACKGROUND: The length of stay in nursing homes before death in Sweden has significantly decreased, and nearly one-third of people die within 6 weeks of entering a nursing home. Support for the next of kin is one of the cornerstones of palliative care, but the principles are not always adhered to as recommended when caring for the elderly, which can affect the quality of life of their next of kin. The aim of this study was to explore the experiences of quality of life among the next of kin of older persons who live in nursing homes before an educational intervention of palliative care. METHODS: This is an explorative qualitative interview study with 40 next of kin using qualitative content analysis performed at baseline before the implementation of the principles of palliative care in nursing homes. RESULTS: The next of kin's experiences of quality of life were expressed in three themes: Orientation to the new life situation, Challenges in their relationship and the Significance of the quality of care in the nursing home. The next of kin experienced a sense of relief, although the older person was constantly on their minds, and they could feel lonely. The difference in the couple'slife situations was experienced as burdensome by the next of kin. The challenges in the relationship were described as stressful, related to a guilty conscience and the older person's vulnerability. The nursing home could be a context facilitating good relations. The perceptions of quality of care in terms of person-centredness affected the quality of life of the next of kin. CONCLUSIONS: The findings show that four factors are decisive for the quality of life of next of kin: the relationships within the family, the degree of relief that nursing home care entails as compared to home care, the older person's health status and whether the care is person-centred. Increased knowledge and education regarding palliative care in nursing homes are needed to better meet the needs of next of kin. Implementation of palliative care should take into account the need for support for next of kin