Download or read book Heavy Quark Production in Gluon Fusion at Two Loops in QCD written by Michal Czakon and published by . This book was released on 2007 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Two loop Virtual QCD Corrections to Higgs Boson Pair Production in the Standard Model written by and published by . This book was released on 2016 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, we compute the next-to-leading order virtual QCD corrections to Higgs-pair production via gluon fusion. We also present analytic results for the two-loop contributions to the spin-0 and spin-2 form factors in the amplitude. The reducible contributions, given by the double-triangle diagrams, are evaluated exactly while the two-loop irreducible diagrams are evaluated by an asymptotic expansion in heavy top-quark mass up to and including terms of O(1/m$8\atop{t}$). We estimate that mass effects can reduce the hadronic cross section by at most 10 %, assuming that the finite top-quark mass effects are of similar size in the entire range of partonic energies.

Download or read book Heavy Quark Production Processes in QCD written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have identified two novel effects in QCD, each of which acts to enhance the production of heavy quark and supersymmetric particles beyond what is conventionally expected from gluon fusion. Both effects are present in QED, but are compounded in QCD because of the increased number of diagrams and the much larger coupling constant. The intrinsic charm quark distribution in the nucleon could account for the observed enhancements of the charm structure function at large x and features of the charm production data but this mechanism is relatively suppressed for heavier systems. Prebinding distortion of the fusion cross section is, however, likely to be significant for the production at low p/sub T/ of all particles containing heavy colored constituents. At this stage the QCD calculations are highly model dependent although they agree with the general properties which can be inferred from the operator product expansion in the heavy quark mass. Much more theoretical analysis of these effects is clearly needed. It is also clear that much more experimental work is necessary to extend and confirm the reported anomalous heavy quark signals. 22 references.

Download or read book QCD Corrections to ZZ Production in Gluon Fusion at the LHC written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We compute the next-to-leading-order QCD corrections to the production of two Z-bosons in the annihilation of two gluons at the LHC. Being enhanced by a large gluon flux, these corrections provide a distinct and, potentially, the dominant part of the N3LO QCD contributions to Z-pair production in proton collisions. The gg → ZZ annihilation is a loop-induced process that receives the dominant contribution from loops of five light quarks, that are included in our computation in the massless approximation. We find that QCD corrections increase the gg → ZZ production cross section by O(50%-100%) depending on the values of the renormalization and factorization scales used in the leading-order computation and the collider energy. Furthermore, the large corrections to the gg → ZZ channel increase the pp → ZZ cross section by about 6% to 8%, exceeding the estimated theoretical uncertainty of the recent next-to-next-to-leading-order QCD calculation.

Download or read book Heavy quark Pair Production at Two Loops in QCD written by Sven-Olaf Moch and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two Loop Amplitudes for Gluon Fusion Into Two Photons written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the two-loop matrix elements for the scattering of two gluons into two photons in QCD. These matrix elements will enter into improved estimates of the QCD background to Higgs production at the LHC when the Higgs decays into two photons. The photon mode is especially important if M[sub H]

Download or read book Higher Order QCD Corrections to Single Top Quark Production written by Mohammad Assadsolimani and published by disserta Verlag. This book was released on 2014-08 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is known that the LHC has a considerable discovery potential because of its large centre-of-mass energy (vs =14 TeV) and the high design luminosity. In addition, the two experiments ATLAS and CMS perform precision measurements for numerous models in physics. The increasing experimental precision demands an even higher level of accuracy on the theoretical side. For a more precise prediction of outcomes, one has to consider the corrections obtained typically from Quantum Chromodynamics (QCD). The calculation of these corrections in the high energy regime is described by perturbation theory. In the present study, multi-loop calculations in QCD, including in particular two-loop corrections for single top quark production, are considered. There are several phenomenological motivations to study single top quark production: Firstly, the process is sensitive to the electroweak Wtb-vertex; moreover, non-standard couplings can hint at physics beyond the Standard Model. Secondly, the t-channel cross section measurement provides information on the b-quark Parton Distribution Functions (PDF). Finally, single top quark production enables us to directly measure the Cabibbo-Kobayashi-Maskawa(CKM) matrix element Vtb. The next-to-next-to-leading-order (NNLO) calculation of the single top quark production has many building blocks. In this study, two blocks will be presented: one-loop corrections squared and two-loop corrections interfered with Born. Initially, the one-loop squared contribution at NNLO for single top quark production will be calculated. Before we begin with the calculation of the two-loop corrections to single top quark production, we calculate the QCD form factors of heavy quarks at NNLO, along with the axial vector coupling as a first independent check. A comparison with the relevant literature suggests that this approach is in line with generally accepted procedure. This consistency check provides a proof of the validity of our setup. In the next step, the two-loop corrections to single top quark production will be calculated. After reducing all occurring tensor integrals to scalar integrals, we apply the integration by parts method (IBP) to find the master integrals. This step is a major challenge compared to all similar calculations because of the number of variables in the problem (two Mandelstam variables s and t, the dimension d and the mass of the top quark mt as well as the mass of the W boson mw). Finally, the calculation of the three kinds of topologies – vertex corrections, double boxes and non-planar double boxes – in the two-loop contribution at NNLO calculation will be presented.

Download or read book Heavy quark Pair Production in Gluon Fusion at Next to next to leading O a4s Order One loop Squared Contributions written by and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heavy Quark Production in Massless Quark Scattering at Two Loops in QCD written by Michal Czakon and published by . This book was released on 2007 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heavy Quark Pair Production in Gluon Fusion at Next to next to leading O63 1hn4 1tns omicron alpha 4 S Order written by and published by . This book was released on 2008 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heavy Quark Pair Production in Gluon Fusion at Next to next to leading 4s omicron alpha 4 S Order written by and published by . This book was released on 2008 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book QCD and Collider Physics written by R. K. Ellis and published by Cambridge University Press. This book was released on 2003-12-04 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed overview of the physics of high-energy colliders emphasising the role of QCD.

Download or read book The Higgs Hunter s Guide written by John F. Gunion and published by CRC Press. This book was released on 2018-03-05 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Higgs Hunter's Guide is a definitive and comprehensive guide to the physics of Higgs bosons. In particular, it discusses the extended Higgs sectors required by those recent theoretical approaches that go beyond the Standard Model, including supersymmetry and superstring-inspired models.

Download or read book Heavy Quark Production in QCD written by and published by . This book was released on 1988 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The 9th International Workshop on Deep Inelastic Scattering DIS 2001 written by G. Bruni and published by World Scientific. This book was released on 2002 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proceedings of DIS 2001 present the most updated status of deep inelastic scattering (DIS) physics. Topics like structure function measurements and phenomenology, QCD studies in DIS and photoproduction, spin physics and diffractive interactions are reviewed in detail, with emphasis on those studies that push the test of QCD and the Standard Model to the limits of their present range of validity, towards both the very high and the very low four-momentum transfers in the lepton-proton scattering. Moreover, this workshop coincided with the transition between the first period of experimentation at the HERA ep collider at DESY and the start of the updated HERA II operation -- allowing a review of what has been learned up to now and a discussion on the main future directions of research in this field.

Download or read book Basics of Perturbative QCD written by Yuri Dokshitzer and published by Atlantica Séguier Frontières. This book was released on 1991 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Physics With New Experiments Proceedings Of Xvi Kazimierz Meeting On Elementary Particle Physics written by Zygmunt Ajduk and published by World Scientific. This book was released on 1994-06-21 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume gives an up-to-date, useful review of the recent results and new ideas concerning the following topics: precision tests of the standard model, search for Higgs bosons, CP violation, flavour physics, neutrino physics, testing extensions of the standard model, supersymmetry, particle physics, cosmology and new results in strong interactions.