A non-rational CFT with c=1 as a limit of minimal models

We investigate the limit of minimal model conformal field theories where the central charge approaches one. We conjecture that this limit is described by a non-rational CFT of central charge one. The limiting theory is different from the free boson but bears some resemblance to Liouville theory. Explicit expressions for the three point functions of bulk fields are presented, as well as a set of conformal boundary states. We provide analytic and numerical arguments in support of the claim that this data forms a consistent CFT.Comment: latex2e, 37 pages, 4 figure

Spatial clusters of gonorrhoea in England with particular reference to the outcome of partner notification: 2012 and 2013

Background: This study explored spatial-temporal variation in diagnoses of gonorrhoea to identify and quantify endemic areas and clusters in relation to patient characteristics and outcomes of partner notification (PN) across England, UK. Methods: Endemic areas and clusters were identified using a two-stage analysis with Kulldorff’s scan statistics (SaTScan). Results Of 2,571,838 tests, 53,547 diagnoses were gonorrhoea positive (positivity = 2.08%). The proportion of diagnoses in heterosexual males was 1.5 times that in heterosexual females. Among index cases, men who have sex with men (MSM) were 8 times more likely to be diagnosed with gonorrhoea than heterosexual males (p<0.0001). After controlling for age, gender, ethnicity and deprivation rank, 4 endemic areas were identified including 11,047 diagnoses, 86% of which occurred in London. 33 clusters included 17,629 diagnoses (34% of total diagnoses in 2012 and 2013) and spanned 21 locations, some of which were dominated by heterosexually acquired infection, whilst others were MSM focused. Of the 53,547 diagnoses, 14.5% (7,775) were the result of PN. The proportion of patients who attended services as a result of PN varied from 0% to 61% within different age, gender and sexual orientation cohorts. A third of tests resulting from PN were positive for gonorrhoea. 25% of Local Authorities (n = 81, 95% CI: 20.2, 29.5) had a higher than expected proportion for female PN diagnoses as compared to 16% for males (n = 52, 95% CI: 12.0, 19.9). Conclusions: The English gonorrhoea epidemic is characterised by spatial-temporal variation. PN success varied between endemic areas and clusters. Greater emphasis should be placed on the role of PN in the control of gonorrhoea to reduce the risk of onward transmission, re-infection, and complications of infection

Detection of K+ mesons in segmented electromagnetic calorimeters

The combination of the CrystalBall and TAPS electromagnetic calorimeters were installed in the MAMI A2 hall in 2003. Here they are able to detect the reaction products from photo-induced reactions in combination with the Glasgow photon tagger. In the last two years the MAMI facility was upgraded from 885 MeV to 1.5 GeV, the A2 photon tagger underwent a similar upgrade crossing the threshold for strangeness photoproduction. For the CrystalBall this created a new challenge, to identify K+ mesons above the large background from other charged hadrons, in a situation where the detector setup does not benefit from a magnetic field to help separate particle species. These proceedings outline a novel technique which uses the decay products of the K+ as a strangeness tag

Parameter estimation and the statistics of nonlinear cosmic fields

The large scale distribution of matter in the universe contains valuable information about fundamental cosmological parameters, the properties of dark matter and the formation processes of galaxies. The best hope of retrieving this information lies in providing a statistical description of the matter distribution that may be used for comparing models with observation. Unfortunately much of the important information lies on scales below which nonlinear gravitational effects have taken hold, complicating both models and statistics considerably. This thesis deals with the distribution of matter - mass and galaxies - on such scales. The aim is to develop new statistical tools that make use of the nonlinear evolution for the purposes of constraining cosmological models.A new derivation for the 1 -point probability distribution function (PDF) for density inhomogeneities is presented first. The calculation is based upon an exact statistical treatment, using the Chapman -Kolmogorov equation and second order Eulerian perturbation theory to propagate the initial density field into the nonlinear regime. The analysis yields the generating function for moments, allowing for a straightforward derivation of the skewness. A new dependance upon the perturbation spectrum is found for the skewness at second order. The results of the analysis are compared against other methods for deriving the 1 -point PDF and against data from numerical N -body simulations. Good agreement is found in both cases.The 1 -point PDF for galaxies is derived next, taking into account nonlinear biasing of the density field and the distorting effects associated with working in redshift space. Once again perturbation theory is used to evolve the density field into the nonlinear regime and the Chapman -Kolmogorov equation to propagate the initial probabilities. Transformation of the dark matter density to a biased galaxy distribution is done through an Eulerian biasing prescription, expanding the nonlinear bias function to second order. An advantage of the Chapman- Kolmogorov approach is the natural way that different initial conditions and biasing models may be incorporated. It is shown that the method is general enough to allow a non -deterministic (hidden variable) bias. The dependance on cosmological parameters of the evolution of the galaxy 1 -point PDF is demonstrated and a method for differentiating between degenerate models in linear theory is presented. A new derivation of the skewness for a biased density field in red - shift space is also given and shown to depend significantly on the density and bias parameters. The results are compared favourably with those of numerical simulations.Finally a new, general formalism for analysing parameter information from non - Gaussian cosmic fields is developed. The method is general enough for application to a range of problems including the measurement of parameters from galaxy redshift surveys, weak lensing surveys and velocity field surveys. It may also be used to test for non -Gaussianity in the Cosmic Microwave Background. Generalising maximum likelihood analysis to second order, the non -Gaussian Fisher information matrix is derived and the detailed shapes of likelihood surfaces in parameter space are explored via a parameter entropy function. Concentrating on non -Gaussianity due to nonlinear evolution under gravity, the generalised Fisher analysis is applied to a model of a Galaxy redshift survey, including the effects of biasing, redshift space distortions and shot noise. Incorporating second order moments into the parameter estimation is found to have a large effect, breaking all of the degeneracies between parameters. The results indicate that using nonlinear likelihood analysis may yield parameter uncertainties around the few percent level from forthcoming large galaxy redshift surveys

Thermodynamic limit of the first-order phase transition in the Kuramoto model

In the Kuramoto model, a uniform distribution of the natural frequencies leads to a first-order (i.e., discontinuous) phase transition from incoherence to synchronization, at the critical coupling parameter $K_c$. We obtain the asymptotic dependence of the order parameter above criticality: $r-r_c \propto (K-K_c)^{2/3}$. For a finite population, we demonstrate that the population size $N$ may be included into a self-consistency equation relating $r$ and $K$ in the synchronized state. We analyze the convergence to the thermodynamic limit of two alternative schemes to set the natural frequencies. Other frequency distributions different from the uniform one are also considered.Comment: 6 page

Finite size effects in perturbed boundary conformal field theories

We discuss the finite-size properties of a simple integrable quantum field theory in 1+1 dimensions with non-trivial boundary conditions. Novel off-critical identities between cylinder partition functions of models with differing boundary conditions are derived.Comment: 7 pages, 11 figures, JHEP proceedings style. Uses epsfig, amssymb. Talk given at the conference `Nonperturbative Quantum Effects 2000', Pari

Magnetar giant flare high-energy emission

High energy ($> 250$ keV) emission has been detected persisting for several tens of seconds after the initial spike of magnetar giant flares. It has been conjectured that this emission might arise via inverse Compton scattering in a highly extended corona generated by super-Eddington outflows high up in the magnetosphere. In this paper we undertake a detailed examination of this model. We investigate the properties of the required scatterers, and whether the mechanism is consistent with the degree of pulsed emission observed in the tail of the giant flare. We conclude that the mechanism is consistent with current data, although the origin of the scattering population remains an open question. We propose an alternative picture in which the emission is closer to that star and is dominated by synchrotron radiation. The $RHESSI$ observations of the December 2004 flare modestly favor this latter picture. We assess the prospects for the Fermi Gamma-Ray Space Telescope to detect and characterize a similar high energy component in a future giant flare. Such a detection should help to resolve some of the outstanding issues.Comment: 20 pages, 14 figure