Framework Convention on Climate Change

Author Ray Pawson presents a devastating critique of the dominant approach to systematic review namely the 'meta-analytic' approach as sponsored by the Cochrane and Campbell collaborations. In its place is commended an approach that he terms 'realist synthesis'. On this vision, the real purpose of systematic review is better to understand program theory, so that policies Author Ray Pawson presents a devastating critique of the dominant approach to systematic review namely the 'meta-analytic' approach as sponsored by the Cochrane and Campbell collaborations. In its place is commended an approach that he terms 'realist synthesis'. On this vision, the real purpose of systematic review is better to understand program theory, so that policies can be properly targeted and developed to counter an ever-changing landscape of social problems. The book will be essential reading for all those who loved (or loathed) the arguments developed in Realistic Evaluation (Sage, 1997). It offers a complete blueprint for research synthesis, supported by detailed illustrations and worked examples from across the policy waterfront.

Evidence-based Policy: A Realist Perspective

We construct a cubic field theory which provides all genus amplitudes of the topological A-model for all non-compact toric Calabi-Yau threefolds. The topology of a given Feynman diagram encodes the topology of a fixed Calabi-Yau, with Schwinger parameters playing the role of Kahler classes of the threefold. We interpret this result as an operatorial computation of the amplitudes in the B-model mirror which is the quantum Kodaira-Spencer theory. The only degree of freedom of this theory is an unconventional chiral scalar on a Riemann surface. In this setup we identify the B-branes on the mirror Riemann surface as fermions related to the chiral boson by bosonization.

/pdf/the-topological-vertex-3lrad1kwkt.pdf

The Topological Vertex

We discuss systematic approaches to the classification of string/M theory vacua, and physical questions this might help us resolve. To this end, we initiate the study of ensembles of effective Lagrangians, which can be used to precisely study the predictive power of string theory, and in simple examples can lead to universality results. Using these ideas, we outline an approach to estimating the number of vacua of string/M theory which can realize the Standard Model.

https://iopscience.iop.org/article/10.1088/1126-6708/2003/05/046/pdf

The statistics of string/M theory vacua

This paper is devoted to recent progress made towards the understanding of closed bosonic and fermionic string perturbation theory, formulated in a Lorentz-covariant way on Euclidean space-time. Special emphasis is put on the fundamental role of Riemann surfaces and supersurfaces. The differential and complex geometry of their moduli space is developed as needed. New results for the superstring presented here include the supergeometric construction of amplitudes, their chiral and superholomorphic splitting and a global formulation of supermoduli space and amplitudes.

The Geometry of String Perturbation Theory

We compute all string tree level correlation functions of vertex operators in $c<1$ string theory. This is done by using the ring structure of the theory. In order to study the multicritical behaviour, we calculate the correlation functions after perturbation by physical vertex operators. We show that the $(2k-1,2)$ models can be obtained from the $(1,2)$ model and the minimal models can be obtained from the $(1,p)$ model by perturbing the action by appropriate physical operators. Our results are consistent with known results from matrix models.

Correlation Functions and Multicritical Flows in $c<1$ String Theory

We point out that the equivalent-photon approximation (EPA) for processes with massive spin-1 particles in the final state would have validity in a more restricted kinematic domain than for processes where it is commonly applied, viz., those with spin-1/2 or spin-0 particles in the final state. We obtain the criterion for the validity ofEPA for the two-photon production of a pair of charged, massive, point-like spin-1 particlesV
 ±, each of massM and with a standard magnetic moment (κ=1). In a process in which one of the photons is real and the other virtual with four-momentumq, the condition for the validity ofEPA is |q
 2|≪M
 2, in addition to the usual condition |q
 2|≪W
 2,W being theV
 +
 V
 − invariant mass. In a process in which both photons are virtual (with four-momentaq andq′), our condition is |q
 2||q′2|W
 4 ≪ 16M
 8, in addition to |q
 2| ≪M
 2, |q′2| ≪M
 2 and |q
 2| ≪W
 2, |q′2| ≪W
 2. Even when these extra conditions permitting the use ofEPA are not fulfilled, convenient approximate expressions may still be obtained assuming merely |q
 2| ≪W
 2 and |q′2| ≪W
 2. We also discuss how the extra conditions are altered when the vector bosons are incorporated in a spontaneously broken gauge theory. Examples ofW boson production in Weinberg-Salam model are considered for which the condition |q
 2||q′2|W
 4 ≪ 16M
 8 is shown to be removed.

Validity of the equivalent-photon approximation for the production of massive spin-1 particles

We show that the process pp (pp-bar)..--> gamma..+..gamma..+X is a powerful test to distinguish between gauged integer-charged-quark models (ICQM's) and fractionally-charged-quark models (FCQM's). We study the ratio of the two-photon production cross section to the lepton-pair production cross section. Below color threshold the ICQM value for this ratio ranges from 30 to 130 in pp collisions (and 10--35 in pp-bar collisions) in the kinematic range of the CERN ISR experiment, whereas the FCQM value is 1.6. The single experimental result available so far appears to disfavor the ICQM.

Two-photon production in pp and pp-bar collisions.

We systematically study and obtain the large-volume analogues of fractional two-branes on resolutions of orbifolds C^3/Z_n. We study a generalisation of the McKay correspondence proposed in hep-th/0504164 called the quantum McKay correspondence by constructing duals to the fractional two-branes. Details are explicitly worked out for two examples -- the crepant resolutions of C^3/Z_3 and C^3/Z_5.

T. Jayaraman

Papers

Correlation Functions and Multicritical Flows in $c<1$ String Theory

Validity of the equivalent-photon approximation for the production of massive spin-1 particles

Two-photon production in pp and pp-bar collisions.

Fractional two-branes, toric orbifolds and the quantum McKay correspondence

Agricultural Science in Colonial India: An Introductory Note