Helicity Amplitudes for Charmonium Production in Hadron-Hadron and Photon-Hadron Collisions (2007)
Meijer, M. M., Smith, J., Van Neerven, W. L.
We present the gluon-gluon and photon-gluon helicity amplitudes for color singlet and octet charmonium production in polarized and unpolarized hadron-hadron and photon-hadron collisions.
QCD threshold corrections to di-lepton and Higgs rapidity distributions beyond N${}^2$LO (2006)
Ravindran, V., Smith, J., Van Neerven, W. L.
We present threshold enhanced QCD corrections to rapidity distributions of di-leptons in the Drell-Yan process and of Higgs particles in both gluon fusion and bottom quark annihilation processes...
Blümlein, J., De Freitas, A., Van Neerven, W. L., Klein, S.
The logarithmic and constant contributions to the Wilson coefficient of the longitudinal heavy quark structure function to $O(\alpha_s^3)$ are calculated using mass factorization techniques in Mellin...
In the framework of the gluon-gluon fusion process for Higgs boson production there are two different prescriptions. They are given by the exact process where the gluons couple via top-quark loops to...
The difference between n-dimensional regularization and n-dimensional reduction in QCD (2004)
We discuss the difference between n-dimensional regularization and n-dimensional reduction for processes in QCD which have an additional mass scale. Examples are heavy flavour production in...
Mathews, Prakash, Ravindran, V., Sridhar, K., Van Neerven, W. L.
The first results on next-to-leading order QCD corrections to graviton-induced processes in hadron collisions in models of TeV-scale gravity are presented focusing on the case of dilepton pair...
Two-loop corrections to Higgs boson production (2004)
Ravindran, V., Smith, J., Van Neerven, W. L.
In this paper we present the complete two-loop vertex corrections to scalar and pseudo-scalar Higgs boson production for general colour factors for the gauge group ${\rm SU(N)}$ in the limit where...
NNLO Corrections to the Higgs Production Cross Section (2004)
Ravindran, V., Smith, J., Van Neerven, W. L.
We discuss the next-to-next-to-leading order (NNLO) corrections to the total cross section for (pseudo-) scalar Higgs boson production. The computation is carried out in the effective Lagrangian...
NNLO Corrections to the Polarized Drell-Yan Coefficient Function (2004)
Ravindran, V., Smith, J., Van Neerven, W. L.
We present the full next-to-next-to-leading order (NNLO) corrections to the coefficient function for the polarized cross section $d \Delta\sigma/d Q$ of the Drell-Yan process. We study the effect of...
Ravindran, V., Smith, J., Van Neerven, W. L.
We present the full next-to-next-to-leading order (NNLO) coefficient functions for the polarized cross section $d\Delta \sigma/dQ$ for the Drell-Yan process $p + p\to l^+l^- + 'X'$. Here $'X'$...
Differential Cross Sections for Higgs Production (2003)
Ravindran, V., Smith, J., Van Neerven, W. L.
We review recent theoretical progress in evaluating higher order QCD corrections to Higgs boson differential distributions at hadron-hadron colliders.
Twist-2 Heavy Flavor Contributions to the Structure Function $g_2(x,Q^2)$ (2003)
Blümlein, J., Ravindran, V., Van Neerven, W. L.
The twist--2 heavy flavor contributions to the polarized structure function $g_2(x,Q^2)$ are calculated. We show that this part of $g_2(x,Q^2)$ is related to the heavy flavor contribution to...
Higgs Production at NNLO (2003)
Ravindran, V., Smith, J., Van Neerven, W. L.
We describe the calculation of inclusive Higgs boson production at hadronic colliders at next-to-next-to-leading order (NNLO) in perturbative quantum chromodynamics. We have used the technique...
Ravindran, V., Smith, J., Van Neerven, W. L.
We present the next-to-next-to-leading order (NNLO) corrections to the total cross section for (pseudo-) scalar Higgs boson production using an alternative method than those used in previous...
NLO corrections to differential cross sections for pseudo-scalar Higgs boson production (2002)
Field, B., Smith, J., Tejeda-Yeomans, M. E., Van Neerven, W. L.
We have computed the full next-to-leading (NLO) QCD corrections to the differential distributions $d^2\sigma/(dp_T~dy)$ for pseudo-scalar Higgs (A) production at large hadron colliders. This...
NLO corrections to the polarized Drell-Yan cross section in proton-proton collisions (2002)
We present the full next-to-leading order (NLO) corrected inclusive cross section for massive lepton pair production in longitudinally polarized proton-proton collisions. All QCD partonic...
Ravindran, V., Smith, J., Van Neerven, W. L.
We present the full next-to-leading order (NLO) corrected inclusive cross section $d^3\Delta \sigma/dQ^2/dy/dp_T$ for massive lepton pair production in longitudinally polarized proton-proton...
Ravindran, V., Smith, J., Van Neerven, W. L.
We present the full next-to-leading order corrected differential distributions $d^2\sigma/dp_T/dy$, $d\sigma/dp_T$ and $d\sigma/dy$ for the semi-inclusive process $p + p\to H + 'X'$. Here $X$ denotes...
Production of Heavy Quarks in Deep-Inelastic Lepton-Hadron Scattering scattering (2001)
We will give a review of the computation of exact next-to-leading order corrections to heavy quark production in deep inelastic lepton-hadron scattering and discuss the progress made in this field...
Parton densities and structure functions at next-to-next-to-leading order and beyond (2001)
We summarize recent results on the evolution of unpolarized parton densities and deep-inelastic structure functions in massless perturbative QCD. Due to last year's extension of the integer-moment...
Non-singlet structure functions beyond the next-to-next-to leading order (2001)
We study the evolution of the flavour non-singlet deep-inelastic structure functions F_{2,NS} and F_3 at the next-to-next-to-next-to-leading order (N^3LO) of massless perturbative QCD. The present...
QCD and power corrections to sum rules in deep-inelastic lepton-nucleon scattering (2001)
Ravindran, V., Van Neerven, W. L.
In this paper we study QCD and power corrections to sum rules which show up in deep inelastic lepton-hadron scattering. Furthermore we will make a distinction between fundamental sum rules which can...
The Drell-Levy-Yan Relation: ep vs $e^+e^-$ Scattering to $O(\alpha_s^2)$ (2001)
Blümlein, J., Ravindran, V., Van Neerven, W. L.
We study the validity of a relation by Drell, Levy and Yan (DLY) connecting the deep inelastic structure (DIS) functions and the single-particle fragmentation functions in $e^+e^-$ annihilation which...
Improved Approximations for the Three-Loop Splitting Functions in QCD (2000)
We update our approximate parametrizations of the three-loop splitting functions for the evolution of unpolarized parton densities in perturbative QCD. The new information taken into account is given...
Parton densities and structure functions beyond the next-to-leading order (2000)
We briefly discuss recent results on the evolution of unpolarized parton densities and structure functions in massless perturbative QCD. Present partial results on the next-to-next-to-leading order...
NNLO evolution of deep-inelastic structure functions: the singlet case (2000)
We study the next-to-next-to-leading order (NNLO) evolution of flavour singlet parton densities and structure functions in massless perturbative QCD. Present information on the corresponding...
QCD corrections up to order alpha_s^2 to polarized quark production in e^+ e^- -annihilation (2000)
Ravindran, V., Van Neerven, W. L.
The revised version contains two additional references i.e. [13], [14] w.r.t. to the original paper. Furthermore Eq. (33) in [11] at the end of the paragraph below (3.17) must be Eq. (33) in [10]....
Catani, S, Dittmar, Michael, Soper, Davison Eugene, Stirling, William James, Tapprogge, Stefan, Alekhin, S I, ...
We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics,...
Catani, S., Dittmar, M., Soper, D., Stirling, W. J., Tapprogge, S., Alekhin, S., ...
We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics,...
On the Drell-Levy-Yan Relation to $O(\alpha_s^2)$ (2000)
Blümlein, J., Ravindran, V., Van Neerven, W. L.
We study the validity of a relation by Drell, Levy and Yan (DLY) connecting the deep inelastic structure (DIS) functions and the single-particle fragmentation functions in e^+e^- annihilation which...
Higher Order Corrections in Perturbative Quantum Chromo Dynamics (2000)
We present some techniques which have been developed recently or in the recent past to compute Feynman graphs beyond one-loop order. These techniques are useful to compute the three-loop splitting...
Bottom quark electroproduction in variable flavor number schemes (2000)
Chuvakin, A., Smith, J., Van Neerven, W. L.
Two variable flavor number schemes are used to describe bottom quark production in deep inelastic electron-proton scattering. In these schemes the coefficient functions are derived from mass...
Heavy Flavor Contributions to QCD Sum Rules and the Running Coupling Constant (1999)
We have calculated first and second order corrections to several sum rules measured in deep inelastic lepton-hadron scattering. These corrections, which are due to heavy flavors only, are compared...
Comparison between variable flavor number schemes for charm quark electroproduction (1999)
Chuvakin, A., Smith, J., Van Neerven, W. L.
Where appropriate, the abbreviation 'VFNS' is replaced by 'CSN' to indicate the scheme using massive heavy quark coefficient functions proposed in this paper. The text below Eq. (2.13) and between...
NNLO evolution of deep-inelastic structure functions: the non-singlet case (1999)
We study the next-to-next-to-leading order (NNLO) evolution of flavour non-singlet quark densities and structure functions in massless perturbative QCD. Present information on the corresponding...
Deep inelastic lepton-hadron scattering as a test of perturbative QCD (1999)
Exploration of the small $x$ kinematic region by the HERA experiments led to a revival of some models which existed before the advent of Quantum Chromo Dynamics (QCD) as the theory of the strong...
Relations among Higher Order QCD corrections (1999)
Blümlein, J., Ravindran, V., Van Neerven, W. L.
We study the scheme transformation of next to leading order QCD corrections to various processes. An interesting relation by Drell, Levy and Yan (DLY) among space like and time like processes is...
Relations among QCD corrections beyond leading order (1998)
Blümlein, J., Ravindran, V., Van Neerven, W. L.
The status of various relations among higher order QCD corrections is discussed. In particular, Drell-Levy-Yan relation and Supersymmetric relation are studied at the two-loop level. We have also...
Less Singular Terms and Small x Evolution in a Soluble Model (1998)
Blümlein, J., Van Neerven, W. L.
We calculate the effect of the less singular terms at small x on the evolution of the coefficient function in \phi^3 theory in six dimensions, which result from a complete solution of the ladder...
Heavy flavour contributions to the deep inelastic sum rules (1998)
Bluemlein, J., Van Neerven, W. L.
We have calculated the first and second order corrections to several deep inelastic sum rules which are due to heavy flavour contributions. A comparison is made with the existing perturbation series...
Ravindran, V., Van Neerven, W. L.
The sentence, 7th line below Eq. (28), starting with "Further we exclude all interference terms ...." is wrong and has been corrected. Eq. (33) : f_k^{l,(i)} -> h_k^{l,(i)} i=0,1 Second line below...
Second order QCD corrections to the forward-backward asymmetry in e^+e^- - collisions (1998)
Ravindran, V., Van Neerven, W. L.
The sentence, 11th line below Eq. (30), starting with "Further in [14] one has included all interference terms ...." is wrong and has been corrected. Second line below Eq. (40) m_bar(m)=m is replaced...
The Unpolarized Gluon Anomalous Dimension at Small x (1998)
Blümlein, J., Ravindran, V., Van Neerven, W. L., Vogt, A.
We discuss the quantitative consequences of the resummation of the small-x contributions to the anomalous dimensions beyond next-to-leading order in alpha_s and up to next order in ln(1/x) (NLx) in a...
On the Gluon Regge Trajectory in $O(\alpha_s^2)$ (1998)
Blümlein, J., Ravindran, V., Van Neerven, W. L.
We recalculate the gluon Regge trajectory in next-to-leading order to clarify a discrepancy between two results in the literature on the constant part. We confirm the result obtained by Fadin et...
Relations among polarized and unpolarized splitting functions beyond leading order (1998)
Blümlein, J., Ravindran, V., Van Neerven, W. L.
The role of various symmetries in the evaluation of splitting functions and coefficient functions is discussed. The scale invariance in hard processes is known to be a guiding tool to understand the...
Higher order QCD Corrections to Fragmentation Functions in e^+~e^- Annihilation (1998)
We analyze the second order QCD corrections to the fragmentation functions F_^H_k(x,Q^2) (k=T,L,A) which are measured in e^+~e^- annihilation From these fragmentation functions one can derive the...
Resummation of Large Logarithms in the Charm Structure Function (1998)
We show how one can resum the large logarithms which occur in the charm component of the structure function F_{k,c}(x,Q^2,m_c^2) (k=2,L) taken at three light flavours, in the limit Q^2 \gg m_c^2....
Matiounine, Y., Smith, J., Van Neerven, W. L.
We present the two-loop corrected operator matrix elements contributing to the scale evolution of the longitudinal spin structure function $g_1(x,Q^2)$ calculated up to finite terms which survive in...
Second order QCD contributions to polarized spacelike and timelike processes (1998)
We will give an outline of the computation of the QCD corrections to the spin structure function g_1(x,Q^2) and the spin fragmentation function g_1^H(x,Q^2) which are measured in deep inelastic...
Two-loop operator matrix elements calculated up to finite terms (1998)
Matiounine, Y., Smith, J., Van Neerven, W. L.
We present the two-loop corrected operator matrix elements calculated in N-dimensional regularization up to the finite terms which survive in the limit $\epsilon = N - 4 \to 0 $. The anomalous...
Rijken, P. J., Van Neerven, W. L.
Misprints in the C_F^2 part of the splitting function \Delta P_{gq}^(1) Eq. (3.29) are corrected. Due to a minus sign error between the C_F^2- 1/2 C_A C_F piece and the remaining part of Eq. (A.4),...
We discuss the order alpha_s^2 corrections to the longitudinal spin structure function g_1(x,Q^2,m^2) which are due to heavy flavour contributions. Here Q denotes the virtuality of the photon and m...
Charm Production in Deep Inelastic Lepton-Hadron Scattering (1997)
A review is given of the QCD corrections to charm quark production in deep inelastic electron-proton scattering. An outline of the computation of the virtual photon-parton subprocesses, from which...
Comparison between the various descriptions for charm electroproduction and the HERA-data (1997)
Buza, M., Matiounine, Y., Smith, J., Van Neerven, W. L.
We examine the charm component F_{2,c}(x,Q^2,m^2) of the proton structure function F_2(x,Q^2) in three different schemes and compare the results with the data in the x and Q^2 region explored by the...
Order alphas**2 Contributions to the Fragmentation Functions in e+ e- Annihilation (1997)
We present the higher order QCD corrections to the fragmentation functions and the corresponding cross sections.
The most important part of the order $\alpha_s^2$ corrections to the charm component of the charged-current structure functions $F_2(x,Q^2)$ and $F_3(x,Q^2)$ have been calculated. This calculation is...
Buza, M., Matiounine, Y., Smith, J., Van Neerven, W. L.
Starting from fixed-order perturbation theory (FOPT) we derive expressions for the heavy-flavour components of the deep-inelastic structure functions FL and F2 in the variable-flavour number scheme...
Deep-inelastic production of heavy quarks (1996)
Laenen, Eric, Buza, M, Harris, B W, Matiounine, Y, Migneron, R, Riemersma, S, ...
Deep-inelastic production of heavy quarks at HERA, especially charm, is an excellent signal to measure the gluon distribution in the proton at small $x$ values. By measuring various differential...
A Detailed Comparison of NLO QCD Evolution Codes (1996)
Blümlein, J., Botje, M., Pascaud, C., Riemersma, S., Van Neerven, W. L., Vogt, A., ...
Seven next-to-leading order QCD evolution programs are compared. The deviations of the results due to different theoretical prescriptions for truncating the perturbative series are clarified, and a...
Rijken, P. J., Van Neerven, W. L.
We present the calculation of the order $\alpha_s^2$ corrections to the coefficient functions contributing to the longitudinal ($F_L(x,Q^2)$) and transverse fragmentation functions ($F_T(x,Q^2)$)...
Rijken, P. J., Van Neerven, W. L.
The order \alpha_s^2 contributions to the coefficient functions corresponding to the asymmetric fragmentation function $F_A(x,Q^2)$ in $e^+e^-$ annihilation are calculated. From this calculation we...
Deep-inelastic production of heavy quarks (1996)
Laenen, E., Buza, M., Harris, B. W., Matiounine, Y., Migneron, R., Riemersma, S., ...
Deep-inelastic production of heavy quarks at HERA, especially charm, is an excellent signal to measure the gluon distribution in the proton at small $x$ values. By measuring various differential...
Review of higher order QCD corrections to structure functions (1996)
A review is presented on all higher order QCD corrections to deep inelastic structure functions. The implications of these corrections for polarized and unpolarized deep inelastic lepton-hadron...
Blümlein, J., Riemersma, S., Van Neerven, W. L., Vogt, A.
The differences are discussed between various next-to-leading order prescriptions for the QCD evolution of parton densities and structure functions. Their quantitative impact is understood to an...
$O(\alpha_s^2)$ corrections to polarized heavy flavour production at $Q^2\gg m^2$ (1996)
Buza, M., Matiounine, Y., Smith, J., Van Neerven, W. L.
We present analytic formulae for the heavy flavour coefficient functions for polarized deep inelastic lepton-hadron scattering. The expressions are valid in the kinematical regime $Q^2\gg m^2$ where...
Van Neerven, W. L., Buza, M., Matiounine, Y., Smith, J., Migneron, R.
Using renormalization group techniques we have derived analytic formulae for the next-to-leading order heavy-quark coefficient functions in deep inelastic lepton hadron scattering. These formulae are...
Rijken, P. J., Van Neerven, W. L.
We present the order $\alpha_s^2$ contributions to the coefficient functions corresponding to the longitudinal fragmentation function $F_L(x,Q^2)$. A comparison with the leading order $\alpha_s$...
Heavy quark coefficient functions at asymptotic values $Q^2 \gg m^2$ (1996)
Buza, M., Matiounine, Y., Smith, J., Migneron, R., Van Neerven, W. L.
In this paper we present the analytic form of the heavy-quark coefficient functions for deep-inelastic lepton-hadron scattering in the kinematical regime $Q^2 \gg m^2$ . Here $Q^2$ and $m^2$ stand...
The Calculation of the Two-Loop Spin Splitting Functions $P_{ij}^{(1)}(x)$ (1995)
Mertig, R., Van Neerven, W. L.
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...
Heavy flavor contributions to the Drell-Yan cross section (1995)
Rijken, P. J., Van Neerven, W. L.
We investigate the effect of heavy flavor contributions to vector boson ($V$ = $\gamma$, $Z$, $W$) production which is described by the Drell-Yan mechanism. All reactions with bottom and top quarks...
Rates for Inclusive Deep-Inelastic Electroproduction of Charm Quarks at HERA (1994)
Riemersma, S., Smith, J., Van Neerven, W. L.
The coefficient functions for heavy-flavour production in deeply inelastic electron-hadron scattering have been calculated previously. Analytic expressions are impossible to publish due to their...
Order $\alpha_s^{2}$ contributions to the Drell-Yan cross section at fixed target energies (1994)
Rijken, P. J., Van Neerven, W. L.
{}From the literature one infers that the bulk of the order $\alpha_{s}$ corrections to the Drell-Yan cross sections $d\sigma/dm$ and $m^{3}d^{2}\sigma/dmdx_{F}$ is constituted by the soft plus...
Top Quark Production Cross Section (1993)
Laenen, E., Smith, J., Van Neerven, W. L.
The production rate for top quarks at the Fermilab Tevatron is presented using the exact order $\alpha_s^3$ corrected cross section and the resummation of the leading soft gluon corrections in all...
Laenen, E., Riemersma, S., Smith, J., Van Neerven, W. L.
We present the complete NLO QCD analysis of the photon structure functions $F_2^\gamma(x,Q^2)$ and $F_L^\gamma(x,Q^2)$ for a real photon target. In particular we study the heavy flavor content of the...
Laenen, E., Riemersma, S., Smith, J., Van Neerven, W. L.
We examine the QCD corrections to the structure functions $F_2^\gamma(x,Q^2)$ and $F_L^\gamma(x,Q^2)$ for a real photon target. The pointlike photon contributions from light and heavy quarks are...
Summary and theoretical basis (1991)
Reya, E, Zerwas, Peter M, Berends, F A, Bordes, G, Cavanna, F, Del Águila, F, ...
Forward-backward asymmetries (1990)
Böhm, M, Hollik, Wolfgang F L, Bardin, Dimitri Yuri, Beenakker, W, Berends, F A, Bilenky, S M, ...