59713563
A summary of the work done using the HPD 1
60484075
Notes on automatic data handling in United States laboratories visited in September 1966, pt 1
117116734
An assessment of the first bubble chamber experiment processed with the HPD at CERN
115543079
Bubble chamber picture measurement
133664820
CHANGES IN MIST
117918920
Procedure for the adjustement of the HPD I optics
119275153
Optimizing future experimental probes of inflation
The discovery of many novel realizations of the inflationary universe paradigm has led to a degeneracy problem: many different inflationary Lagrangians generate the same perturbation spectra. Resolving this problem requires the future discovery of additional observables beyond the scalar adiabatic and tensor two-point functions on CMB scales. One important source of degeneracy arises in models where the density perturbation is generated by a noninflationary degree of freedom, for example, through curvatons or modulated reheating. We consider the curvaton scenario as representative of this class, and analyze the degeneracy with single field, canonical inflation that results if the curvaton goes undetected by future observations. We perform Monte Carlo potential reconstructions in the absence of distinguishing observables, such as non-Gaussiantities or isocurvature modes. The resulting degeneracy is considerable and the improved measurements of spectral parameters from future probes like CMBPol offer little to better the situation. Given a degeneracy-breaking observation, the observables must still be inverted to obtain the inflationary potential, with different observations resulting in reconstructions of varying quality. We find that a future detection of isocurvature modes or a precision measurement of the tensor spectral index will enable the most successful reconstructions in the presence of curvatons.
54917997
Tensor tilt from primordial B modes
A primordial cosmic microwave background B mode is widely considered a ‘smoking gun’ signature of an early period of inflationary expansion. However, competing theories of the origin of structure, including string gases (SG) and bouncing cosmologies, also produce primordial tensor perturbations that give rise to a B mode. These models can be differentiated by the scale dependence of their tensor spectra: inflation predicts a red tilt (nT 0), while a non-singular matter bounce gives a zero tilt (nT = 0). We perform a Bayesian analysis to determine how far |nT| must deviate from zero before a tilt can be detected with current and future B-mode experiments. We find that Planck in conjunction with Q/U Imaging Experiment II will decisively detect nT � 0i f |nT| > 0.3, too large to distinguish either single-field inflation or SG from the case nT = 0. While a future mission like CMBPol will offer improvement, only an ideal satellite mission will be capable of providing sufficient Bayesian evidence to distinguish between each model considered.
118690762
Cosmological constraints on rapid roll inflation
We obtain cosmological constraints on models of inflation which exhibit rapid roll solutions. Rapid roll attractors exist for potentials with large mass terms and are thus of interest for inflationary model building within string theory. We constrain a general ansatz for the power spectrum arising from rapid roll inflation that, in the small field limit, can be associated with tree level hybrid potentials with variable mass terms and nonminimal gravitational coupling ?R2. We consider perturbations generated through modulated reheating and/or curvaton mechanisms in place of the observationally unacceptable primary spectra generated by inflaton fluctuations in these models. The lack of a hierarchy amongst higher-order k-dependencies of the power spectrum results in models with potentially large runnings, allowing us to impose tight constraints on such models using CMB and LSS data. In particular, we find ns < 1 and |?| < 0.01. We conclude with a concrete realization of rapid roll inflation within warped throat brane inflation that is in good agreement with current data.
119273003
Observational signatures of gravitational couplings in DBI inflation
In scalar-tensor theories the scalar fields generically couple nontrivially to gravity. We study the observable properties of inflationary models with nonminimally coupled inflaton and Dirac-Born-Infeld (DBI) kinetic term. Within the assumptions of the priors of our Monte-Carlo simulations we find these models can generate new interesting observable signatures. Our discussion focuses on string theory inspired phenomenological models of relativistic D-brane inflation. While successful string theory constructions of ultraviolet DBI brane inflation remain elusive, we show that in suitable regions of the parameter space it is possible to use cosmological observables to probe the nonminimal coupling. Fortunately, the most observationally promising range of parameters include models yielding intermediate levels of non-Gaussianity in the range consistent with WMAP 5-year data, and to be constrained further by the Planck satellite.
24800285
Identifying the inflaton with primordial gravitational waves.
We explore the ability of experimental physics to uncover the underlying structure of the gravitational Lagrangian describing inflation. While the observable degeneracy of the inflationary parameter space is large, future measurements of observables beyond the adiabatic and tensor two-point functions, such as non-gaussianity or isocurvature modes, might reduce this degeneracy. We show that, even in the absence of such observables, the range of possible inflaton potentials can be reduced with a precision measurement of the tensor spectral index, as might be possible with a direct detection of primordial gravitational waves.