Related papers: Orthopositronium Decay Spectrum using NRQED
We calculate the radiative corrections to the unpolarized and the four polarized spectrum and rate functions in the leptonic decay of a polarized $ \mu $ into a polarized electron. The new feature of our calculation is that we keep the mass…
The $\alpha$ phase of $Ga_{2}O_{3}$ is an ultra-wideband semiconductor with potential power electronics applications. In this work, we calculate the low field electron mobility in $\alpha-Ga_{2}O_{3}$ from first principles. The 10 atom unit…
We consider a Hamiltonian with cutoffs describing the weak decay of spin one massive bosons into the full family of leptons. The Hamiltonian is a self-adjoint operator in an appropriate Fock space with a unique ground state. We prove a…
The neutron-neutron fusion process, $nn\to de\nu$, at very low neutron energies is studied in the framework of pionless effective field theory that incorporates dibaryon fields. The cross section and electron energy spectrum for this…
In this work, we illustrate the recently introduced concept of the cavity Born-Oppenheimer approximation for correlated electron-nuclear-photon problems in detail. We demonstrate how an expansion in terms of conditional electronic and…
We study the decays $\pi^{+}\to l^{+}\nu_{l}$ in the presence of a background electromagnetic plane wave with circular polarization. We find that, in the presence of this background, the number of hadronic form factors required to describe…
The interaction of charged particles and photons with intense electromagnetic fields gives rise to multi-photon Compton and Breit-Wheeler processes. These are usually described in the framework of the external field approximation, where the…
Rare decays of light mesons may be a discovery window for a new weakly coupled forces hidden at low energy QCD scale. BES-III Collaboration reported the observation of the rare decay $\eta'\rightarrow\pi^0\gamma\gamma$. The observed decay…
We consider a system of $N$ nonrelativistic particles which form a near-threshold resonance. Assuming no subset of these particles can form a bound state, the resonance can only decay through an "explosion" into $N$ particles. We show that…
For systems of $N$ charged fermions (e.g. electrons) interacting with longitudinal optical quantized lattice vibrations of a polar crystal we derive upper and lower bounds on the minimal energy within the model of H. Fr\"ohlich. The only…
Taking into account mixings among neutrino states, the end of the energy spectrum of the electron in the tritium beta decay is investigated. It is shown that for real energy resolutions of a spectrometer, $ \Delta E > 0.08$ eV, the…
We present the design and experimental proof of principle of a low threshold optical parametric oscillator (OPO) that continuously oscillates over a large bandwidth allowed by phase matching. The large oscillation bandwidth is achieved with…
The shape of the electron energy spectrum in 3H beta-decay permits a direct assay of the absolute scale of the neutrino mass; a highly accurate theoretical description of the electron energy spectrum is necessary to the empirical task. We…
The low lying spectrum of the O(n) effective field theory is calculated in the delta-regime in 3 and 4 space-time dimensions using lattice regularization to NNL order. It allows, in particular, to determine, using numerical simulations in…
We investigate the effects of colour-octet contributions to the radiative $\Upsilon$ decay within the Bodwin, Braaten and Lepage NRQCD factorization framework. Photons coming both from the coupling to hard processes (`direct') and by…
We analyze $h\to 4\ell$ decays in the kinematical region where the dilepton pair of low invariant mass ($m_{34}$) is not far from QCD resonances ($\Psi$ and $\Upsilon$ states). On the one hand, we present precise predictions of the spectrum…
The results of a new search for positronium decays into invisible final states are reported. Convincing detection of this decay mode would be a strong evid ence for new physics beyond the Standard Model (SM): for example the existence of…
The motion of electrons under homogeneously applied electric fields in low-dimensional systems with non-zero off-diagonal effective mass (ODEM) is studied. The equation describing the time evolution of a probability coefficient of finding…
In a general framework that has been labeled the ``gauging of equations method'', we study the diagrams that contribute to Compton scattering off a relativistic composite system. These contributions can be derived for $N$--particle bound…
We consider the structure-dependent amplitude of the decay $B_s \to l^+ l^- \gamma$ $(l=e,\mu)$ in a model based on the effective Hamiltonian for $b \bar{s} \to l^+ l^-$ containing the Wilson coefficients $C_7,C_9$ and $C_{10}$. The form…