Related papers: The double fermionic contribution to the four-loop…
We study perturbative and non-perturbative aspects of heavy-quark fragmentation into hadrons, emphasizing the large-x region, where x is the energy fraction of the detected hadron. We first prove that when the moment index N and the quark…
We report on the status of the calculation of deep-inelastic structure functions at three loops in perturbative QCD. The method employed allows to calculate the Mellin moments of structure functions analytically as a general function of N.…
We present a first study of gluonic twist-four corrections to the deep inelastic structure function F_2 at small x and small Q^2. The calculations are based upon the double logarithmic approximation of the coupled twist-four evolution…
The scale evolution of parton distributions is governed by splitting functions. We compute the four-loop splitting functions in perturbative QCD that control the evolution of quark non-singlet distributions. We confirm previous partial…
We compute the virtual O(alpha_s^2) fermionic contributions to the charm quark mass dependent matrix elements of the B -> X_s gamma decay. In the case of a massless quark loop insertion into the gluon propagator, our result obtained as an…
The contributions of scalars and fermions to the null polygonal bosonic Wilson loops/gluon MHV scattering amplitudes in $\mathcal{N} = 4$ SYM are considered. We first examine the re-summation of scalars at strong coupling. Then, we…
We give explicit formulae for the O(eps) and O(eps^2) contributions to the unrenormalised three loop QCD corrections to quark and gluon form factors. These contributions have at most transcendentality weight eight. The O(eps) terms of the…
We shown the general approach for Q2 evolution of parton densities and fragmentation functions at low x based on the diagonalization. The diagonalization leads to the two components in the Q2 evolution, each of which contains a…
We analyze the iterative structure of unfactorized partonic structure functions in the large-x limit, and derive all-order expressions for the leading-logarithmic off-diagonal splitting functions P_gq and P_qg and the corresponding…
We investigate the properties of composite fermions with four attached flux quanta through tilted field experiments near Landau level filling factor nu = 3/4. The observed collapse of fractional quantum Hall gaps in the vicinity of this…
The next-to-next-to-leading order (NNLO) corrections in massless perturbative QCD are derived for the parton distributions of the photon and the deep inelastic structure functions F_1^gamma and F_2^gamma. We present the full photonic…
We study the transverse-momentum spectrum of quarkonium production from single light-parton fragmentation mechanism. In the case of semi-inclusive deep inelastic scattering, we observe that there are two possible initiating processes,…
We apply finite-size recursion techniques based on the Schrodinger functional formalism to determine the renormalization group running of four-fermion operators which appear in the Delta S=2 effective weak Hamiltonian of the Standard Model.…
Low- and intermediate mass Higgs bosons decay preferably into fermion pairs. The one-loop electroweak corrections to the respective decay rates are dominated by a flavour-independent term of ${\cal O}(G_Fm_t^2)$. We calculate the two-loop…
We present results for the non-perturbative renormalisation of four-fermion operators with two flavours of dynamical quarks. We consider both fully relativistic left current-left current operators, and a full basis for $\Delta B=2$…
We compute the eighth-order fermionic corrections involving two and three closed massless fermion loops to the anomalous magnetic moment of the muon. The required four-loop on-shell integrals are classified and explicit analytical results…
Using Schroedinger Functional methods, we compute the non-perturbative renormalisation and renormalisation group running of several four-fermion operators, in the framework of lattice simulations with two dynamical Wilson quarks. Two…
We present the calculation of the two-loop spin splitting functions $P_{ij}^{(1)}(x)\; (i,j = q,g)$ contributing to the next-to-leading order corrected spin structure function $g_1(x,Q^2)$. These splitting functions, which are presented in…
I present results for the resummation of soft and collinear gluon contributions to QCD hard-scattering cross sections at two loops. This requires the calculation of UV and IR divergences through two loops and the construction of soft…
We perform a perturbative QCD analysis of the nucleon's Pauli form factor $F_2(Q^2)$ in the asymptotically large $Q^2$ limit. We find that the leading contribution to $F_2(Q^2)$ has a $1/Q^6$ power behavior, consistent with the well-known…