119058989
Measuring CMB polarization with Boomerang
Boomerang is a balloon-borne telescope designed for long duration (LDB) flights around Antarctica. The second LDB flight of Boomerang took place in January 2003. The primary goal of this flight was to measure the polarization of the CMB. The receiver uses polarization sensitive bolometers at 145 GHz. Polarizing grids provide polarization sensitivity at 245 and 345 GHz. We describe the Boomerang telescope noting changes made for 2003 LDB flight, and discuss some of the issues involved in the measurement of polarization with bolometers. Lastly, we report on the 2003 flight and provide an estimate of the expected results.
15621530
Constraining large–scale structure theories with the cosmic background radiation
The case is strong that cosmic microwave background (CMB) and large scale structure (LSS) observations can be combined to determine the theory of structure formation and the cosmological parameters that define it. We review: the relevant (10+) parameters associated with the inflation model of fluctuation generation and the matter content of the universe; the relation between LSS and primary and secondary CMB anisotropy probes as a function of wavenumber; how COBE constraints on energy injection rule out explosions as a dominant source of LSS; and how current anisotropy band–powers in multipole–space, at levels ca. 10−5)2, strongly support the gravitational instability theory and suggest the universe could not have reionized too early. We use Bayesian analysis methods to determine what current CMB and CMB+LSS data imply for inflation–based Gaussian fluctuations in tilted &Lgr;CDM, &Lgr;hCDM and oCDM model sequences with cosmological age 11 – 15 Gyr, consisting of mixtures of baryons, cold ‘c’ (and possibly hot ‘h’) dark matter, vacuum energy &Lgr;, and curvature energy ‘o’ in open cosmologies. For example, we find the slope of the initial spectrum is within about 5% of the (preferred) scale–invariant form when just the CMB data are used, and for &Lgr;CDM when LSS data are combined with CMB; with both, a non–zero value of Ω&Lgr; is strongly preferred (ca. ⅔ for a 13 Gyr sequence, similar to the value from SNIa). The oCDM sequence prefers Ωtot < 1, but is overall much less likely than the flat Ω&Lgr; ≠ 0 sequence with CMB+LSS. We also review the rosy forecasts of angular power spectra and parameter estimates from future balloon and satellite experiments when foreground and systematic effects are ignored to show where cosmic parameter determination can go with CMB information alone.
119408227
CMB likelihood functions for beginners and experts
Although the broad outlines of the appropriate pipeline for cosmological likelihood analysis with CMB data has been known for several years, only recently have we had to contend with the full, large-scale, computationally challenging problem involving both highly-correlated noise and extremely large datasets (N>1000). In this talk we concentrate on the beginning and end of this process. First, we discuss estimating the noise covariance from the data itself in a rigorous and unbiased way; this is essentially an iterated minimum-variance mapmaking approach. We also discuss the unbiased determination of cosmological parameters from estimates of the power spectrum or experimental bandpowers.
17460509
Simultaneous Estimation of Noise and Signal in Cosmic Microwave Background Experiments
To correctly analyse data sets from current microwave detection technology, one is forced to estimate the sky signal and experimental noise simultaneously. Given a time-ordered data set we propose a formalism and method for estimating the signal and associated errors without prior knowledge of the noise power spectrum. We derive the method using a Bayesian formalism and relate it to the standard methods; in particular we show how this leads to a change in the estimate of the noise covariance matrix of the sky signal. We study the convergence and accuracy of the method on two mock observational strategies and discuss its application to a currently-favoured calibration procedure.
119468667
Gravitational Waves Probe the Coalescence Rate of Massive Black Hole Binaries
We calculate the expected nHz-μHz gravitational wave (GW) spectrum from coalescing massive black hole (MBH) binaries resulting from mergers of their host galaxies. We consider detection of this spectrum by precision pulsar timing and a future pulsar timing array. The spectrum depends on the merger rate of massive galaxies, the demographics of MBHs at low and high redshift, and the dynamics of MBH binaries. We apply recent theoretical and observational work on all of these fronts. The spectrum has a characteristic strain hc(f) ~ 10-15(f/yr-1)-2/3, just below the detection limit from recent analysis of precision pulsar timing measurements. However, the amplitude of the spectrum is still very uncertain owing to approximations in the theoretical formulation of the model, to our lack of knowledge of the merger rate and MBH population at high redshift, and to the dynamical problem of removing enough angular momentum from the MBH binary to reach a GW-dominated regime.
122687802
Imaging the early universe with the BOOMERanG Experiment
The BOOMERanG experiment has recently detected temperature fluctuations the Cosmic Microwave Background (CMB), the otherwise isotropic radiation coming from the early Universe. These anisotropies have a low contrast (about 30 ppm) and feature a peculiar angular power spectrum at angles corresponding to sub-horizon scales at recombination. In the current cosmological model, these structures result from acoustic oscillations in the primeval plasma. In the framework of the Hot Big Bang theory with the inflationary hypothesis, the statistical properties of the image of the CMB allow us to measure most of the cosmological parameters.
118568324
Classical Gauge Theories and Their Quantum Role
The classical Euclidean variational equations (δA= 0, where A is the action functional, play two important roles. First, in dimension d ≤ 3 they provide time independent solutions to classical four-dimensional physics. In that way, for example, the Ginzburg-Landau model has proved important in the theory of superconductivity. The second role of Euclidean stationary points of the action is to provide a starting point for classical approximations to quantum fields. We make some remarks on these two topics; for classical gauge theories we restrict attention to the Higgs model.
118881742
Constructive Field Theory, Phase II
It now appears possible to study a realm of problems in CFT which, two years ago, appeared an order of magnitude too difficult to tackle. The finishing touches have just been put on the first paper of this sort1, and in this talk I will describe some of the basic ideas; these ideas are simple, although the details of the paper are complicated. The main question that I will discuss today has been around as long as field theory: Namely how does an interacting field model react to perturbations by an external source? Such perturbations of \(\textup{P}\left (\phi \right )_{2}\), or in fact any reasonable local perturbations of the \(\textup{P}\left (\phi \right )_{2}\) model, have been shown to be regular by James Glimm and myself1. As a consequence, (i) further properties of the original model have been established1, (ii) some new breakthroughs are being made2 and (iii) these methods appear promising for use in the study of more singular models than \(\textup{P}\left (\phi \right )_{2}\).
120239182
Quantum Field Theory Models
Quantum fields are believed to provide a correct description of the interactions between particles. In the case of quantum electrodynamics, calculations based on perturbation theory provide exact agreement between theory and experiment within the limits of experimental accuracy. These calculations rely on infinite renormalizations and therefore reveal that quantum fields are highly singular. In these lectures, we will be concerned with the qualitative structure of quantum fields. Given a classical Lagrangian, we seek a mathematically complete construction of the corresponding quantum fields. Because of the difficulty of this problem, we have restricted ourselves to two space time dimensions. With this restriction, the program has been successful. Quantum fields have been constructed for the o2n and Yukawa interactions in two dimensions. Many properties of the fields have been verified for these models, and the o2n theory obeys all the Haag-Kastler axioms. Two major unanswered questions are: 
 
a) 
 
Can the existence of local quantum fields be extended to three space time dimensions? 
 
 
 
 
b) 
 
For the two dimensional models, can detailed properties of the fields be established in order to describe elementary particles and their bound states? Is standard perturbation theory asymptotic to the exact solution of the models? Do standard dispersion relations hold for the cross sections?
123634325
HIGH-ENERGY BEHAVIOR IN QUANTUM FIELD THEORY. I. STRICTLY LOCALIZABLE FIELDS.
We introduce the notion of a field which is strictly localizable within a region of space-time. We investigate what restrictions strict localizability imposes on the high-energy behavior of fields, and we find that it leads to an upper bound on the growth of a field in momentum space. This bound allows the off-mass-shell vacuum expectation values to grow in momentum space faster than any polynomial. Furthermore, it turns out that no maximum rate of growth exactly saturates our bound. In addition, strictly localizable fields need not be Schwartz distributions. However, the usual distribution fields are strictly localizable fields of a special type. We formulate a strictly local field theory in precise mathematical terms. Finally, we discuss simple examples of strictly localizable fields that are not distributions.
119653427
Quark Trapping for Lattice U(1) Gauge Fields
Abstract We show for lattice U(1) gauge fields in d = 3 dimensions, that 〈exp(i∮ C A d x )〉 ⩽ exp (− const. T ln L ), where C is a rectangle of dimension T × L , T ⩾ L . This indicates quark trapping, by a potential at least as strong as Coulomb.