Models which accelerate the expansion of the universe through the addition of a function of the Ricci scalar f(R) leave a characteristic signature in the large-scale structure of the universe at the Compton wavelength scale of the extra scalar degree of freedom. We search for such a signature in current cosmological data sets: the WMAP cosmic microwave background (CMB) power spectrum, SNLS supe...

This article investigates into the feasibility of using gamma radiation Compton backscatter spectra as a means of material characterization, with the view to developing a portable, hand held probe for investigative purposes such as searching for illicit substances hidden in wall or car door cavities.

In this paper we calculate the cross section for Virtual Compton Scattering off nuclei in the delta resonance region. We also calculate the background for the process from Coherent Bremsstrahlung in nuclei and explore the regions where the Virtual Compton Scattering cross section dominates. The study also shows that it is possible to extract the cross section for Real Compton Scattering from th...

Recent observations of gamma-ray bursts (GRBs) have provided growing evidence for collimated outflows and emission, and strengthened the connection between GRBs and supernovae. If massive stars are the progenitors of GRBs, the hard photon pulse will propagate in the pre-burst, dense environment. Circumstellar material will Compton scatter the prompt GRB radiation and give rise to a reflection e...

Free electrons deplete photons from type Ia supernovae through the (inverse) Compton scattering. This Compton dimming increases with redshift and reaches 0.004 mag at z = 1 and 0.01 mag at z = 2. Although far from sufficient to invalidate the existence of dark energy, it can bias constraint on dark energy at a level non-negligible for future supernova surveys. This effect is correctable and sho...

We present a new theoretical approach to attosecond laser-assisted photoand Compton ionization. Attosecond x-ray absorption and scattering are described by Ŝ (1,2)-matrices, which are coherent superpositions of ‘monochromatic’ Ŝ(1,2)-matrices in a laser-modified Furry representation. Besides refining the existing theory of the soft x-ray photoelectron attosecond streak camera and spectral phase...

Virtual Compton scattering in the ∆-resonance region is considered in the case of a target nucleus. The discussion involves generalized polar-izabilities and is developed for zero-spin nuclei, focusing on the new information coming from virtual Compton scattering in comparison with real Compton scattering.

A quantum field theoretic treatment of the leading light–cone part of the virtual Compton amplitude is presented. The twist–decomposition of the operators is performed by a group–theoretic procedure respecting the Lorentz group O(3, 1). The twist–2 contributions to the Compton amplitude are calculated and it is shown that the electromagnetic current is conserved for these terms. Relations betwe...

The Compton positron source of a future linear collider must obtain the target bunch population by accumulating a large number of positron packets, arriving either in a number of bursts from a ‘Compton ring’, with intermediate damping of the scattering electron beam, or quasicontinually from a ‘Compton energy recovery linac’. We present simulation results for the longitudinal stacking of Compto...

Recent x-ray Compton scattering experiments in ice have provided useful information about the quantum nature of the interaction between H2O monomers. The hydrogen bond is characterized by a certain amount of charge transfer which could be determined in a Compton experiment. We use ab initio simulations to investigate the hydrogen bond in H2O structures by calculating the Compton profile and rel...