Graviton plus vector boson production to NLO in QCD at the LHC

We present the next-to-leading order QCD corrections to the associated production of the vector gauge boson (Z/W^±$Z/W^{\pm }$) and the graviton in the large extra dimension model at the LHC. We estimate the impact of the QCD corrections on the total cross sections as well as the differential distributions of the gauge bosons and find that they are significant. We also study the dependence of the cross sections on the arbitrary factorization scale and show the reduction in the scale uncertainties at NLO level. Further, we discuss the ultraviolet sensitivity of the theoretical predictions.     

Non-leading QCD contributions in W boson production

We calculate the transverse momentum distribution of decay-leptons from W bosons produced in p$\text{p}$ scattering. It is shown that the inclusion of non-leading QCD contributions induces a remarkable change on the shape of the jacobian peak. We propose the use of the complete QCD formula to make a meaningful analysis of the experimental data.     

Low Q^2 jet production at HERA in next-to-leading order QCD

We present next-to-leading order calculations of one- and two-jet production in eP collisions at HERA for photon virtualities in the range GeV. Soft and collinear singularities are extracted using the phase space slicing method. Numerical results are presented for HERA conditions with the Snowmass jet definition. The transition between photoproduction and deep-inelastic scattering is investigated in detail. We compare two approaches, the usual deep-inelastic theory, where the virtual photon couples only directly to quarks and antiquarks, and the photoproduction approach, where the photon couples either in the direct way or in the resolved way via the parton constituents of the virtual photon with the proton constituents. Finally we compare with recent H1 data of the dijet rate obtained for various photon virtualities with special attention to the region, in which two jets have equal transverse momenta. Received: 23 April 1998 / Published online: 26 August 1998     

On the zero mass boson in QCD2

The zero-mass boson in QCD₂ is shown to gain mass in the next to leading order in $\text{1}\text{N}$ expansion, in agreement with Coleman's Theorem.     

Higgs boson production on protons within the QCD semihard approach

Higgs boson (H) production in proton-proton collisions via the mechanism of gluon-gluon fusion is considered within the QCD semihard (k _T-factorization) approach. Results are presented that were obtained by calculating the total and differential cross sections for inclusive Higgs boson production in \(p\bar p \to H + X\) processes at the Tevatron collider and LHC energies. It is shown that, even in the leading order, the QCD semihard approach makes it possible to study processes involving the associated production of Higgs bosons and one or two hadron jets. Various azimuthal correlations arising in such processes between the transverse momenta of final particles are analyzed. The dependence of all calculated quantities on the choice of unintegrated gluon distribution in the proton is examined.     

Inclusive jet production with virtual photons in next-to-leading order QCD

We present a next-to-leading order calculation for the virtual photoproduction of one and two jets inep collisions. Soft and collinear singularities are extracted using the phase space slicing method. The collinear photon initial state singularity depends logarithmically on the mass of the virtual photon and is absorbed into the virtual photon structure function. An $\overline {MS} $ factorization scheme is defined similarly to the real photon case. Numerical results are presented for HERA conditions using the Snowmass jet definition for inclusive single jet and dijet cross sections. We study the dependence of these cross sections on the transverse energies and rapidities of the jets. Finally, we compare the ratio of the experimentally defined resolved and direct cross sections with recent ZEUS data as a function of the photon virtualityP ².     

On inclusive gluon jet production off the nucleus in perturbative QCD

In the perturbative QCD approach single and double inclusive cross-sections for gluon production off the nucleus are studied by the relevant reggeized gluon diagrams. Various terms corresponding to emission of gluons from the triple pomeron vertex are found. Among them the term derived by Kovchegov and Tuchin emerges as a result of the transition from the diffractive to effective high-energy vertex. However it does not exhaust all the vertex contributions to the inclusive cross-section. In the double inclusive cross-section a contribution violating the naive AGK rules is found in which one gluon is emitted from the vertex and the other from one of the two pomerons below the vertex. But then this contribution is subdominant at high energies and taking it into account seems to be questionable.Received: 6 March 2005, Revised: 5 May 2005, Published online: 8 June 2005     

Large-PT jet production in QCD

The contribution from qq → qq + X scattering to the large-P_T jet cross section in hadronic collisions is calculated in quantum chromodynamics to order O(g⁶). The result finds a suggestive interpretation in the Parisi-Altarelli parton model, which yields also the general formula, including all quark-gluon subprocesses.     

Next-to-leading-order QCD corrections to WW + jet production at hadron colliders

We report on the calculation of the next-to-leading-order QCD corrections to the production of W-boson pairs in association with a hard jet at the Fermilab Tevatron and CERN Large Hadron Collider, which is an important source of background for Higgs boson and new-physics searches. The corrections stabilize the leading-order prediction for the cross section considerably, in particular, if a veto against the emission of a second hard jet is applied.     

Glauber shadowing in jet and particle production in nucleus-nucleus collisions within perturbative QCD

Inclusive cross sections for jet and hadron production in nucleus-nucleus collisions are computed within perturbative QCD with allowance for multiple parton rescattering. Nuclear shadowing due to parton rescattering is negligible at the RHIC energies, but it becomes significant at the LHC energy.     

Electroweak Higgs boson production in the standard model effective field theory beyond leading order in QCD

We study the impact of dimension-six operators of the standard model effective field theory relevant for vector-boson fusion and associated Higgs boson production at the LHC. We present predictions at the next-to-leading order accuracy in QCD that include matching to parton showers and that rely on fully automated simulations. We show the importance of the subsequent reduction of the theoretical uncertainties in improving the possible discrimination between effective field theory and standard model results, and we demonstrate that the range of the Wilson coefficient values allowed by a global fit to LEP and LHC Run I data can be further constrained by LHC Run II future results.