Related papers: Resummation in (F)APT
We present an approximate NNLO evaluation of the QCD form factor resumming large logarithmic perturbative contributions in semi-inclusive heavy flavour decays.
After reviewing basic facts about large-order behaviour of perturbation expansions in various fields of physics, I consider several alternatives to the Borel summation method and discuss their relevance to different physical situations.…
We have recently presented the complete O(alpha_s^2) corrections to the semileptonic decay width of the b quark at maximal recoil. Here we discuss various technical aspects of that calculation and further applications of similar methods. In…
We compute the decoupling function of the MSbar renormalized fine-structure constant up to four-loop order in perturbative QCD. The results are used in order to determine the related top-quark contributions to the Higgs-boson decay into two…
Within the nonrelativistic QCD (NRQCD) factorization framework, we compute the order-$\alpha_s^3$ perturbative corrections to the leptonic decay of the $\Upsilon$ and $J/\psi$ with high numerical accuracy, at the lowest order in velocity…
We revisit the power counting of the Higgs Effective Field Theory (HEFT) from first principles, by requiring that predictions for physical observables follow a series expansion in small, dimensionless quantities. Depending on whether HEFT…
We study the applicability of Pade Approximants (PA) to estimate a "sum" of asymptotic series of the type appearing in QCD. We indicate that one should not expect PA to converge for positive values of the coupling constant and propose to…
I briefly review some recent results on soft-gluon resummation and present applications to heavy-quark and jet production in hadron collisions.
We analyze the dark matter power spectrum at three-loop order in standard perturbation theory of large scale structure. We observe that at late times the loop expansion does not converge even for large scales (small momenta) well within the…
We present a detailed analysis of the non-analytic structure of the free energy for the itinerant ferromagnet near the quantum critical point in two and three dimensions. We analyze a model of electrons with an isotropic dispersion…
In this article, we recalculate the contributions of all vacuum condensates up to dimension-6, in particular the one-loop corrections to the quark condensates $\alpha_s<\bar{q}q>$ and partial one-loop corrections to the four-quark…
The process $H \to J/\psi + \gamma$, where $H$ is the Higgs particle, provides a way to probe the size and the sign of the Higgs-charm coupling. In order to improve the theoretical control of the decay rate, we compute order $v^4$…
We calculate the full electroweak one-loop corrections to the decay of the CP-odd Higgs boson A^0 into scalar fermions in the minimal supersymmetric extension of the Standard Model. For this purpose many parameters of the MSSM have to be…
In this contribution, we present our recent study on the second-order corrections of pseudo-scalar($A$) Higgs decay to three partons, at higher orders in the dimensional regulator. We have studied the one and two-loop amplitudes for…
We present an analytical calculation of additional real or virtual radiation of the light fermion pair in the fermionic decay of the Higgs boson $ H \to f_1\bar f_1$ for arbitrary ratios of the Higgs boson mass to the $f_1$ fermion mass.…
We discuss Pad\'e-improvement of known four-loop order results based upon an asymptotic three-parameter error formula for Pad\'e-approximants. We derive an explicit formula estimating the next-order coefficient $R_4$ from the previous…
Different choices exist for the renormalisation group resummation in the determination of $\alpha_s$ from hadronic $\tau$ decays: namely fixed-order (FOPT) and contour-improved perturbation theory (CIPT). The two approaches lead to…
The O(alpha_s) SUSY QCD corrections to the decays of the MSSM Higgs bosons into bottom quarks and squarks can be very large for large tan beta in the on--shell renormalization scheme. We improve the calculation by a careful choice of the…
We compute the QCD form factor resumming threshold logarithms in B --> X_c + l + nu_l decays to next-to-leading logarithmic approximation. We present an interpolation formula including soft as well as collinear effects softened by the…
Within the complete heavy quark effective field theory (HQEFT), the QCD sum rule approach is used to evaluate the decay constants including 1/m_Q corrections and the Isgur-Wise function and other additional important wave functions…