Related papers: Primordial helium recombination II: two-photon pro…
We measure the effective optical depth of HeII Ly\alpha\ absorption \tau$_\mathsf{eff,HeII}$ at 2.3<z<3.5 in 17 UV-transmitting quasars observed with UV spectrographs on the Hubble Space Telescope (HST). The median \tau$_\mathsf{eff,HeII}$…
An introduction to nucleosynthesis, the creation of the elements in the big bang, in interstellar matter and in stars is given. The two--step process $^4$He(2n,$\gamma$)$^6$He and the reverse photodisintegration $^6$He($\gamma$,2n)$^4$He…
The CMB bispectrum generated by second-order effects at recombination can be calculated analytically when one of the three modes has a wavelength much longer than the other two and is outside the horizon at recombination. This was pointed…
Interfacial charge separation and recombination at heterojunctions of monolayer transition metal dichalcogenides (TMDCs) are of interest to two dimensional optoelectronic technologies. These processes can involve large changes in parallel…
It is shown that taking into account a recoil for radiation scattering in the Ly-alpha line can lead to a noticable acceleration of primordial hydrogen recombination. Thus for LambdaCDM model a decrease of ionization degree exceeds 1% for…
Coherent control of interfering one- and two-photon processes has for decades been the subject of research to achieve the redirection of photocurrent. The present study develops two-pathway coherent control of ground state helium atom…
A key assumption of the standard cosmological model is that the temperature of the cosmic microwave background (CMB) radiation scales with cosmological redshift $z$ as $T_{\rm CMB}(z) \propto (1+z)$ at all times after recombination at…
The intergalactic helium became fully ionized by the end of cosmic noon ($z\sim2$). Similarly to the reionization of hydrogen, helium reionization is expected to be patchy, driven by luminous quasars that ionize the intergalactic gas in…
Stimulated by a recent measurement of coherent control in photoionization of atomic barium, we have calculated one- and two-photon ionization cross sections of the aligned 6s6p^1P_1 state of barium in the energy range between the 5d_{3/2}…
Two-photon absorption is theoretically analyzed within the semiclassical formalism of radiation-matter interaction. We consider an ensemble of inhomogeneously broadened three-level atoms subjected to the action of two counterpropagating…
The perturbations in the electron number density during recombination contributes to the Cosmic Microwave Background bispectrum through second order terms. Perturbations in the electron density can be a factor of ~5 larger than the baryon…
Non-thermal photons deriving from radiative transitions among the internal ladder of atoms and molecules are an important source of photons in addition to thermal and stellar sources in many astrophysical environments. In the present work…
The interference of two independent single-photon pulses impinging on a beam splitter is analysed in a generalised time-resolved manner. Different aspects of the phenomenon are elaborated using different representations of the single-photon…
We present the results of several collisional-radiative models describing optically-thin emissivities of the main lines in neutral helium formed by recombination, for a grid of electron temperatures and densities, typical of H II regions…
The first search for the $B_s^0\rightarrow K^-\pi^+\gamma$ decay in the range $796<m(K^-\pi^+)<1800\,\text{MeV/}c^2$ is performed using data from proton-proton collisions collected by the LHCb experiment at centre-of-mass energies of 7, 8,…
We have combined the detailed He I recombination model of Smits with the collisional transitions of Sawey & Berrington in order to produce new accurate helium emissivities that include the effects of collisional excitation from both the 2…
Feasibility of a measurement of the partial decay width of the intermediate-mass Higgs boson into two photons at a photon-photon collider is studied by a simulation. The QCD radiative correction for quark pair background processes is taken…
There are few data available with which to constrain the thermal history of the intergalactic medium (IGM) following global recombination. Thus far, most constraints flow from analyses of the Cosmic Microwave Background and optical…
When modelling the ionisation of gas in the intergalactic medium after reionisation, it is standard practice to assume a uniform radiation background. This assumption is not always appropriate; models with radiative transfer show that…
We show that dark matter annihilation around the time of recombination can lead to growing ionization fraction perturbations, that track the linear collapse of matter over-densities. This amplifies small scale cosmological perturbations to…