相关论文: Box diagram contribution to the axial two-nucleon …
Quantum Monte Carlo calculations of electromagnetic moments and transitions are reported for A <= 9 nuclei. The realistic Argonne v18 two-nucleon and Illinois-7 three-nucleon potentials are used to generate the nuclear wave functions.…
We compute next-to-next-to-leading order perturbative corrections to the decay width difference of mass eigenstates and the charge-parity asymmetry $a_{\rm fs}$ in flavour-specific decays of neutral $B$ mesons. In our calculation we take…
We report on the recent developments of a new effective field theory for nuclear matter [1,2,3]. We present first the nuclear matter chiral power counting that takes into account both short-- and long--range inter-nucleon interactions. It…
The next-to-leading-order contribution to the amplitude of a two-body decay process is a triangle-shaped diagram in which the unstable state is exchanged by the emitted particles. In this work we calculate this diagram in the framework of a…
We compute the leading non-analytic contributions of the form m_q Log(m_q) to matrix elements of twist-2 operators in the nucleon and pion using effective field theory. Previously omitted one-loop contributions that are related to…
Working in the linear sigma model with quarks, we compute the finite-temperature effective potential in the presence of a weak magnetic field, including the contribution of the pion ring diagrams and considering the sigma as a classical…
Recent results on the entirely analytic calculation of second order corrections to massive quark pair production vertices induced by light quark flavours are reviewed. Based on the method presented in this talk the second order effects of…
We work out a specific class of three-loop diagrams (of order $\alpha_s^2$) contributing to the decay amplitude for $b \to s \gamma$ associated with the current-current operators $O_1$ and $O_2$ at the physical value of the charm-quark mass…
We present the two-pion exchange contributions to the nucleon-nucleon interaction up to next-to-next-to-next-to leading order (N$^3$LO) in covariant baryon chiral perturbation theory. Both one-loop and two-loop diagrams are calculated with…
We estimate the correction to the Cooper-pair box energy level splitting due to the quantum motion of a coupled micromechanical gate electrode. While the correction due to zero-point motion is very small, it should be possible to observe…
We calculate in baryon chiral perturbation theory the relativistic $1/M^2$-corrections to the leading order two-pion exchange diagrams. We give explicit expressions for the corresponding one-loop NN-amplitudes in momentum space. The…
We discuss in detail the derivation of the leading four-nucleon force in chiral effective field theory using the method of unitary transformation. The resulting four-nucleon force is given in both momentum and configuration space. It does…
We study the nucleon-nucleon interaction up to next-to-next-to-leading order using time-ordered perturbation theory in the framework of manifestly Lorentz-invariant chiral effective field theory. We present the two-pion exchange…
We perform an analysis of triangle- and box-loop contributions to the generalized potential in the scattering of Goldstone bosons off the J^P= 0^- and 1^- charmed mesons. Particular emphasis is put on the use of on-shell mass parameters in…
In this paper, we generalize the unitarity method to two-loop diagrams and use it to discuss the integral bases of reduction. To test out method, we focus on the four-point double-box diagram as well as its related daughter diagrams, i.e.,…
Recently, we have derived a two--nucleon potential and consistent nuclear electromagnetic currents in chiral effective field theory with pions and nucleons as explicit degrees of freedom. The calculation of the currents has been carried out…
A new approach is presented to evaluate multi-loop integrals, which appear in the calculation of cross-sections in high-energy physics. It relies on a fully numerical method and is applicable to a wide class of integrals with various mass…
We consider the counter-term describing isoscalar axial two-body currents in the nucleon-nucleon interaction, L1A, in the effective field theory approach. We determine this quantity using the solar neutrino data. We investigate the…
We investigate the reaction pn -> dpipi in the framework of Chiral Perturbation Theory. For the first time a complete calculation of the leading order contributions is presented. We identify various diagrams that are of equal importance as…
The problem of the higher-loop contributions to the axial anomaly is reexamined by a new method. We demonstrate that these contributions depend on the order of the calculations. If the divergence of the axial current by nonperturbative…