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Articles de revues sur le sujet « NNLO calculation »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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1

FERROGLIA, ANDREA. « QCD CORRECTIONS TO THE RADIATIVE DECAY $\bar{B}\to X_s\gamma$ ». Modern Physics Letters A 23, no 37 (7 décembre 2008) : 3123–40. http://dx.doi.org/10.1142/s021773230802879x.

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In this short review, the calculation of the next-to-next-to-leading order QCD corrections to the inclusive radiative decay [Formula: see text] is described. We summarize the salient features of the calculational framework adopted, discuss the results obtained in the last few years, and indicate the technical tools that made the NNLO calculations possible. We conclude by comparing the current NNLO theoretical estimate for the branching ratio with the experimental measurement and by briefly discussing the size and origin of the residual theoretical uncertainty.
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Giménez, Vicent, Leonardo Giusti, Guido Martinelli et Federico Rapuano. « NNLO unquenched calculation of the b quark mass ». Journal of High Energy Physics 2000, no 03 (13 mars 2000) : 018. http://dx.doi.org/10.1088/1126-6708/2000/03/018.

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Gimenéz, V. « NNLO unquenched calculation of the b quark mass ». Nuclear Physics B - Proceedings Supplements 83-84, no 1-3 (mars 2000) : 286–88. http://dx.doi.org/10.1016/s0920-5632(00)00254-1.

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Giménez, V., L. Giusti, F. Rapuano et G. Martinelli. « NNLO unquenched calculation of the b quark mass ». Nuclear Physics B - Proceedings Supplements 83-84 (avril 2000) : 286–88. http://dx.doi.org/10.1016/s0920-5632(00)91649-9.

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Contogouris, A. P., et G. Grispos. « Approximate calculation of corrections at NLO and NNLO ». Nuclear Physics B - Proceedings Supplements 96, no 1-3 (avril 2001) : 94–97. http://dx.doi.org/10.1016/s0920-5632(01)01115-x.

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WANG, JIAN, GUOMING CHEN et WEIMIN WU. « THE IMPACT OF LO, NLO AND NNLO FOR THE HIGGS SEARCHING AT $\sqrt{s} = 7$ TeV OF LHC ». Modern Physics Letters A 25, no 36 (30 novembre 2010) : 3027–31. http://dx.doi.org/10.1142/s0217732310034146.

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Most of current Monte Carlo studies on the Higgs searching are based on LO, or NLO calculation. However, in recent years, the next-to-next-to-leading order (NNLO) corrections have been computed for some physics process, and found that the cross section increases the kinematics changes. As the results, the analysis results could be impacted by these high order QCD corrections. We use standard Monte Carlo generator for LO, as well as MC@NLO for NLO and ResBos for NNLO at 7 TeV of LHC to evaluate this impact for physics channel of the Higgs, mass at 165 GeV, to WW, then W decay to lepton and neutrino as the final states. We found the signal rate could be effected by ratio of 1:2.6:3.4 for LO, NLO and NNLO using the same standard H→WW→lνlν searching analysis process.6
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Santiago, J., et F. J. Ynduráin. « Calculation of electroproduction to NNLO and precision determination of αs ». Nuclear Physics B 563, no 1-2 (décembre 1999) : 45–62. http://dx.doi.org/10.1016/s0550-3213(99)00441-1.

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Canko, D. D., A. Kardos, C. G. Papadopoulos, A. V. Smirnov, N. Syrrakos et C. Wever. « Progress on Feynman Integrals for 2 → 3 scattering at NNLO ». Journal of Physics : Conference Series 2105, no 1 (1 novembre 2021) : 012009. http://dx.doi.org/10.1088/1742-6596/2105/1/012009.

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Abstract We present recent results on two-loop five-point Feynman Integrals with one off-shell leg that are relevant to the study of many 2 → 3 scattering processes of interest at the LHC, especially for the leading-colour W + 2 jets production. The calculation is based on the Simplified Differential Equations approach.
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HARLANDER, ROBERT, et WILLIAM KILGORE. « HIGGS PRODUCTION IN GLUON FUSION TO ${\mathcal O} (\alpha^4_s)$ ». International Journal of Modern Physics A 16, supp01a (octobre 2001) : 305–7. http://dx.doi.org/10.1142/s0217751x01006760.

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The calculation of the NNLO QCD corrections to the partonic process gg → H is outlined. For the coupling of the Higgs boson to the gluons we use an effective Lagrangian in the limit of a heavy top quark. The focus is on the evaluation of the virtual two-loop corrections. It is shown that the leading ole terms are in agreement with general formula by Catani.
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10

Ferrera, Giancarlo, Massimiliano Grazzini et Francesco Tramontano. « Associated ZH production at hadron colliders : The fully differential NNLO QCD calculation ». Physics Letters B 740 (janvier 2015) : 51–55. http://dx.doi.org/10.1016/j.physletb.2014.11.040.

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11

Bondarenko, S., et S. Pozdnyakov. « NNLO classical solution for Lipatov’s effective action for reggeized gluons ». International Journal of Modern Physics A 34, no 20 (20 juillet 2019) : 1950111. http://dx.doi.org/10.1142/s0217751x19501112.

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We consider the formalism of small-[Formula: see text] effective action for reggeized gluons[Formula: see text] and, following the approach developed in Refs. 11–17, calculate the classical gluon field to NNLO precision with fermion loops included. It is demonstrated that for each perturbative order, the self-consistency of the equations of motion is equivalent to the transversality conditions applied to the solution of the equations, these conditions allow to construct the general recursive scheme for the solution’s calculation. The one fermion loop contribution to the classical solutions and application of the obtained results are also discussed.
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12

Su, Nan. « Recent progress in hard-thermal-loop QCD thermodynamics and collective excitations ». International Journal of Modern Physics A 30, no 09 (25 mars 2015) : 1530025. http://dx.doi.org/10.1142/s0217751x15300252.

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I review recent developments in QCD thermodynamics and collective excitations from the hard-thermal-loop effective theory. I begin by motivating the discussion with open questions from heavy-ion collisions. I then discuss a finite-temperature and density calculation of QCD thermodynamics at NNLO from the hard-thermal-loop perturbation theory. Finally, I discuss a recent exploration of generalizing the hard-thermal-loop framework to the (chromo)magnetic scale g2T, from which a novel massless mode is uncovered.
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13

Rana, Narayan. « Mixed QCD-EW two-loop amplitudes for neutral current Drell-Yan production ». Journal of Physics : Conference Series 2438, no 1 (1 février 2023) : 012145. http://dx.doi.org/10.1088/1742-6596/2438/1/012145.

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Abstract We present the mixed QCD-EW two-loop virtual amplitudes for the neutral current Drell-Yan production. The evaluation of the two-loop amplitudes is one of the bottlenecks for the complete calculation of the NNLO mixed QCD-EW corrections. We present the computational details, especially the evaluation of all the relevant two-loop Feynman integrals using analytical and semi-analytical methods. We perform the subtraction of universal infrared singularities and present the numerical evaluation of the hard function.
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14

Fan, Zhouyou, Rui Zhang et Huey-Wen Lin. « Nucleon gluon distribution function from 2 + 1 + 1-flavor lattice QCD ». International Journal of Modern Physics A 36, no 13 (28 avril 2021) : 2150080. http://dx.doi.org/10.1142/s0217751x21500809.

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The parton distribution functions (PDFs) provide process-independent information about the quarks and gluons inside hadrons. Although the gluon PDF can be obtained from a global fit to experimental data, it is not constrained well in the large-[Formula: see text] region. Theoretical gluon-PDF studies are much fewer than those of the quark PDFs. In this work, we present the first lattice-QCD results that access the [Formula: see text]-dependence of the gluon unpolarized PDF of the nucleon. The lattice calculation is carried out with nucleon momenta up to 2.16 GeV, lattice spacing [Formula: see text] fm, and with valence pion masses of 310 and 690 MeV. We use reduced Ioffe-time distributions to cancel the renormalization and implement a one-loop perturbative pseudo-PDF gluon matching. We neglect mixing of the gluon operator with the quark singlet sector. Our matrix-element results in coordinate space are consistent with those obtained from the global PDF fits of CT18 NNLO and NNPDF3.1 NNLO. Our fitted gluon PDFs at both pion masses are consistent with global fits in the [Formula: see text] region.
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15

Eskola, K. J., V. J. Kolhinen, P. V. Ruuskanen et R. L. Thews. « Effects of Shadowing on Drell–Yan Dilepton Production in High Energy Nuclear Collisions ». International Journal of Modern Physics E 12, no 02 (avril 2003) : 197–209. http://dx.doi.org/10.1142/s0218301303001260.

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We compute cross sections for the Drell–Yan process in nuclear collisions at next-to-leading order (NLO) in αs. The effects of shadowing on the normalization and on the mass and rapidity dependence of these cross sections are presented. An estimate of higher order corrections is obtained from next-to-next-to-leading order (NNLO) calculation of the rapidity-integrated mass distribution. Variations in these predictions resulting from choices of parton distributions sets are discussed. Numerical results for mass distributions at NLO are presented for RHIC and LHC energies, using appropriate rapidity intervals. The shadowing factors in the dilepton mass range 2 < M < 10 GeV are predicted to be substantial, typically 0.5 - 0.7 at LHC, 0.7 - 0.9 at RHIC, and approximately independent of the choice of parton distribution sets and the order of calculation.
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16

SALAM, GAVIN P. « DEVELOPMENTS IN PERTURBATIVE QCD ». International Journal of Modern Physics A 21, no 08n09 (10 avril 2006) : 1778–91. http://dx.doi.org/10.1142/s0217751x06032757.

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A brief review of key recent developments and ongoing projects in perturbative QCD theory, with emphasis on conceptual advances that have the potential for impact on LHC studies. Topics covered include: twistors and new recursive calculational techniques; automation of one-loop predictions; developments concerning NNLO calculations; the status of Monte Carlo event generators and progress in matching to fixed order; analytical resummation including the push to NNLL, automation and gap between jets processes; and progress in the understanding of saturation at small x.
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17

Santiago, J., et F. J. Ynduráin. « Improved calculation of F2 in electroproduction and xF3 in neutrino scattering to NNLO and determination of αs ». Nuclear Physics B 611, no 1-3 (septembre 2001) : 447–66. http://dx.doi.org/10.1016/s0550-3213(01)00328-5.

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18

Ocalan, Kadir. « Accurate prediction of the Drell-Yan ϕη* distribution in wide dilepton mass and rapidity ranges in pp collisions through NNLO+N3LL ». Physica Scripta 96, no 12 (1 décembre 2021) : 125323. http://dx.doi.org/10.1088/1402-4896/ac3e19.

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Abstract This paper presents high-accuracy predictions for the differential cross ss as a function of the key observable ϕ η * of the neutral-current Drell-Yan (DY) dilepton production in proton-proton (pp) collisions. The differential distributions for the ϕ η * are presented by using the state-of-the-art predictions from the combined calculations of fixed-order perturbative quantum chromodynamics (QCD) corrections at next-to-next-to-leading order (NNLO) accuracy and resummation of large logarithmic terms at next-to-next-to-leading logarithmic (NNLL) and next-to-NNLL (N3LL) accuracies, i.e., NNLO+NNLL and NNLO+N3LL, respectively. The predicted distributions are reported for a thorough set of the DY dilepton invariant mass m ll ranges, spanning a wide kinematic region of 50 < m ll < 1000 GeV both near and away from the Z-boson mass peak, and rapidity y ll ranges in the central detector acceptance region of ∣y ll ∣ < 2.4. The differential ϕ η * distributions in the wide m ll and y ll ranges offer stringent tests to assess the reliability of the predictions, where the m ll and y ll are closely correlated with the parton distribution functions (PDFs) of the incoming partons. The matched predictions through NNLO+N3LL are observed to provide good description of the 13 TeV pp collision data for the ϕ η * (including the dilepton transverse momentum p T ll as well) distributions in almost the entire m ll and y ll ranges, apart from the intermediate- to high- ϕ η * region in the lowest mass range 50–76 GeV which is assessed to constitute a challenge for the presented predictions. The predictions at NNLO+N3LL are also reported at 14 TeV for the upcoming high-luminosity running era of the Large Hadron Collider (LHC), in which increasing amount of data is expected to require more accurate and precise theoretical description. The most recent PDF models MSHT20 and CT18, in addition to the NNPDF3.1, are tested for the first time for the matched predictions of the ϕ η * distribution. The differential distributions by the combined predictions through NNLO QCD+NLO EW are finally provided to enable assessment of the impact of the EW corrections for the ϕ η * .
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19

Santiago, J., et F. J. Ynduráin. « NNLO calculation of DIS ; Precision determination of the strong coupling constant, extraction of the gluon density, and comments on “hidden” gluinos ». Nuclear Physics B - Proceedings Supplements 86, no 1-3 (juin 2000) : 69–73. http://dx.doi.org/10.1016/s0920-5632(00)00544-2.

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20

Becher, Thomas, et Matthias Neubert. « Toward a NNLO calculation of the B¯→Xsγ decay rate with a cut on photon energy : I. Two-loop result for the soft function ». Physics Letters B 633, no 6 (février 2006) : 739–47. http://dx.doi.org/10.1016/j.physletb.2006.01.006.

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Becher, Thomas, et Matthias Neubert. « Toward a NNLO calculation of the B¯→Xsγ decay rate with a cut on photon energy : II. Two-loop result for the jet function ». Physics Letters B 637, no 4-5 (juin 2006) : 251–59. http://dx.doi.org/10.1016/j.physletb.2006.04.046.

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KIDONAKIS, NIKOLAOS. « A UNIFIED APPROACH TO NNLO SOFT AND VIRTUAL CORRECTIONS IN ELECTROWEAK, HIGGS, QCD, AND SUSY PROCESSES ». International Journal of Modern Physics A 19, no 11 (30 avril 2004) : 1793–821. http://dx.doi.org/10.1142/s0217751x04018294.

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I present a unified approach to calculating the next-to-next-to-leading order (NNLO) soft and virtual QCD corrections to cross-sections for electroweak, Higgs, QCD, and SUSY processes. I derive master formulas that can be used for any of these processes in hadron–hadron and lepton–hadron collisions. The formulas are based on a unified threshold resummation formalism and can be applied to both total and differential cross-sections for processes with either simple or complex color flows and for various factorization schemes and kinematics. As a test of the formalism, I rederive known NNLO results for Drell–Yan and Higgs production, deep inelastic scattering, and W+γ production, and I obtain expressions for several two-loop anomalous dimensions and other quantities needed in next-to-next-to-leading-logarithm (NNLL) resummations. I also present new results for the production of supersymmetric charged Higgs bosons; massive electroweak vector bosons; photons; heavy quarks in lepton–hadron and hadron–hadron collisions and in flavor-changing neutral current processes; jets; and squarks and gluinos. The NNLO soft and virtual corrections are often dominant, especially near threshold, and they reduce the scale dependence of the cross-section. Thus, a unified approach to these corrections is important in the search for new physics at present and future colliders.
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BEDNYAKOV, A. V. « ON THE TWO-LOOP DECOUPLING CORRECTIONS TO τ-LEPTON AND b-QUARK RUNNING MASSES IN THE MSSM ». International Journal of Modern Physics A 25, no 12 (10 mai 2010) : 2437–56. http://dx.doi.org/10.1142/s0217751x10048494.

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Masses of heavy Standard Model (SM) fermions (top-quark, bottom-quark and tau-lepton) play an important role in the analysis of theories beyond the SM. They serve as low-energy input and reduce the parameter space of such theories. In this paper Minimal supersymmetric extension of the SM is considered and two-loop relations between known SM values of fermion masses and running parameters of the MSSM are studied within the effective theory approach. Both b-quark and τ-lepton have the same quantum numbers with respect to SU(2) group and in the MSSM acquire their masses due to interactions with the same Higgs doublet. As a consequence, for large values of tan β parameter corresponding Yukawa couplings also become large and together with tan β can significantly enhance radiative corrections. In the case of b-quark two-loop [Formula: see text] contribution to the relation between running bottom-quark mass in QCD and MSSM is known in literature. This paper is devoted to calculation of the NNLO corrections proportional to Yukawa couplings. For the τ-lepton obtained contribution can be considered as a good approximation to the full two-loop result. For the b-quark numerical analysis given in the paper shows that only the sum of strong and Yukawa corrections can play such a role.
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KIDONAKIS, NIKOLAOS, et RAMONA VOGT. « THEORETICAL STATUS OF THE TOP QUARK CROSS SECTION ». International Journal of Modern Physics A 20, no 14 (10 juin 2005) : 3171–73. http://dx.doi.org/10.1142/s0217751x05026054.

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We discuss the most recent calculations of the top quark total cross section and transverse momentum distributions at the Tevatron and the LHC. These calculations include the soft-gluon corrections at next-to-next-to-leading order (NNLO). The soft NNLO corrections stabilize the scale dependence of the cross section.
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25

Heinrich, Gudrun. « A numerical method for NNLO calculations ». Nuclear Physics B - Proceedings Supplements 116 (mars 2003) : 368–72. http://dx.doi.org/10.1016/s0920-5632(03)80201-3.

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Glover, E. W. N. « Progress in NNLO calculations for scattering processes ». Nuclear Physics B - Proceedings Supplements 116 (mars 2003) : 3–7. http://dx.doi.org/10.1016/s0920-5632(03)80133-0.

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Gehrmann-De Ridder, A., T. Gehrmann et E. W. N. Glover. « Antenna subtraction method for jet calculations at NNLO ». Nuclear Physics B - Proceedings Supplements 157, no 1 (juillet 2006) : 32–36. http://dx.doi.org/10.1016/j.nuclphysbps.2006.03.006.

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Grazzini, M. « Steps towards NNLO QCD calculations : collinear factorization at ″(αS2) ». Nuclear Physics B - Proceedings Supplements 79, no 1-3 (octobre 1999) : 441–43. http://dx.doi.org/10.1016/s0920-5632(99)00747-1.

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Poncelet, R. « NNLO QCD Calculations with the Sector-improved Residue Subtraction Scheme ». Acta Physica Polonica B 51, no 6 (2020) : 1503. http://dx.doi.org/10.5506/aphyspolb.51.1503.

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Dilsiz, Kamuran, et Emrah Tiras. « Inclusive W boson QCD predictions and lepton charge asymmetry in proton–proton collisions at = 14 TeV ». Canadian Journal of Physics 96, no 9 (septembre 2018) : 1029–33. http://dx.doi.org/10.1139/cjp-2017-0635.

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Inclusive W ([Formula: see text]) boson QCD predictions and lepton charge asymmetry in proton–proton collisions at [Formula: see text] = 14 TeV is performed in this study. Total and fiducial cross section predictions are obtained up to next to next to leading order (NNLO) QCD corrections using Monte Carlo for FeMtobarn processes (MCFM) MC generator. To validate the predictions, a detailed comparison of NNLO QCD calculations with 8 TeV CMS results is performed. To discuss the advantage of the higher order QCD predictions on the scale uncertainty, a scale dependence study is presented based on the choice of renormalization (μR) and factorization (μF) scale variations. W boson – lepton charge asymmetry and differential cross section as a function of lepton pseudorapidity at [Formula: see text] = 14 TeV are further performed in 11 |η| regions.
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ELLIS, JOHN. « SUMMARY OF ICHEP 2004 ». International Journal of Modern Physics A 20, no 22 (10 septembre 2005) : 5297–315. http://dx.doi.org/10.1142/s0217751x05028806.

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Aspects of ICHEP 2004 are summarized from a theoretical point of view. QCD works, new NNLO calculations are becoming available and new string calculational tools are emerging, but no conclusions can yet be drawn about the discovery of the quark-gluon plasma or pentaquarks. The small upward shift in the experimental value of mt raises somewhat the central value of the Higgs mass extracted from a global electroweak fit, and the CKM model describes well the data from the B factories. The Super-Kamiokande, KamLAND and K2K experiments have evidence for oscillation dips in their neutrino data. Little Higgs models are interesting alternatives to low-energy supersymmetry for stabilizing the electroweak scale. Convincing experimental evidence for dark matter particles is still lacking. The LHC is on its way, the technology choice clarifies the roadmap for the ILC, and a multi-TeV CLIC would also have rich physics agenda.
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CONTOGOURIS, A. P., et Z. MEREBASHVILI. « APPROXIMATE NEXT-TO-LEADING ORDER AND NEXT-TO-NEXT-TO-LEADING ORDER CORRECTIONS ». International Journal of Modern Physics A 18, no 06 (10 mars 2003) : 957–66. http://dx.doi.org/10.1142/s0217751x03013983.

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For processes involving structure functions and/or fragmentation functions, arguments that over a range of a proper kinematic variable, there is a part that dominates the next-to-leading order (NLO) corrections, are briefly reviewed. The arguments are tested against more recent NLO and in particular complete next-to-next-to-leading order (NNLO) calculations. A critical examination of when these arguments may not be useful is also presented.
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Potluru, Vamsi. « Frugal Coordinate Descent for Large-Scale NNLS ». Proceedings of the AAAI Conference on Artificial Intelligence 26, no 1 (20 septembre 2021) : 2451–52. http://dx.doi.org/10.1609/aaai.v26i1.8432.

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The Nonnegative Least Squares (NNLS) formulation arises in many important regression problems. We present a novel coordinate descent method which differs from previous approaches in that we do not explicitly maintain complete gradient information. Empirical evidence shows that our approach outperforms a state-of-the-art NNLS solver in computation time for calculating radiation dosage for cancer treatment problems.
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NEKRASOV, M. L. « MODIFIED PERTURBATION THEORY FOR ANGULAR DISTRIBUTION IN W-PAIR PRODUCTION ». Modern Physics Letters A 27, no 32 (11 octobre 2012) : 1250195. http://dx.doi.org/10.1142/s0217732312501957.

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We examine the capabilities of the modified perturbation theory (MPT) for description of W-pair production and decay in e+ e- annihilation. In a model with Dyson-resummed propagators of unstable particles, we calculate even and odd contributions to the distribution in the cosine of the W- production angle relative to the e- beam. On comparing the results of calculations in the NNLO approximation of MPT with the exact results in the model, a coincidence of outcomes at the ILC energies is detected at the per-mille level.
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NEKRASOV, M. L. « MODIFIED PERTURBATION THEORY FOR PAIR PRODUCTION AND DECAY OF FUNDAMENTAL UNSTABLE PARTICLES ». International Journal of Modern Physics A 24, no 32 (30 décembre 2009) : 6071–103. http://dx.doi.org/10.1142/s0217751x09047673.

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We construct an asymptotic expansion in powers of the coupling constant directly of the cross-section for pair production and decay of fundamental unstable particles. The resonant and kinematic singularities arising in the expansion we treat in the sense of distributions. This mode allows us to transform formally divergent integrals into absolutely convergent ones with keeping the asymptotic property of the expansion. The appropriate procedure is elaborated up to an arbitrary order of the expansion. The peculiarity of application of the procedure in the threshold region is analyzed. The scheme of the calculations within the NNLO approximation is explicitly discussed.
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36

Soldatov, E. Yu. « Standard Model physics at ATLAS ». EPJ Web of Conferences 222 (2019) : 01002. http://dx.doi.org/10.1051/epjconf/201922201002.

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The latest advances in Standard Model measurements performed by the ATLAS experiment at the LHC are discussed. Vector-boson scattering processes have been observed in several final states (ZZ, WZ, same-sign WW), and evidence has been reached in the Zγ final state. The experimental precision of QCD measurements has reached the same order as the theoretical uncertainties on the NNLO calculations. Evidence for the triboson WVV final state has been achieved. The latest results on V+jets, Zγ, W+W− and direct photons production are presented. New results on jet substructure and forward proton tagging program are also discussed.
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37

Moch, S., J. A. M. Vermaseren et A. Vogt. « Onγ5in higher-order QCD calculations and the NNLO evolution of the polarized valence distribution ». Physics Letters B 748 (septembre 2015) : 432–38. http://dx.doi.org/10.1016/j.physletb.2015.07.027.

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38

Alioli, Simone, Alessandro Broggio, Alessandro Gavardi, Stefan Kallweit, Matthew A. Lim, Riccardo Nagar, Davide Napoletano et Luca Rottoli. « Precise predictions for photon pair production matched to parton showers in GENEVA ». Journal of High Energy Physics 2021, no 4 (avril 2021). http://dx.doi.org/10.1007/jhep04(2021)041.

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Abstract We present a new calculation for the production of isolated photon pairs at the LHC with $$ {\mathrm{NNLL}}_{{\mathcal{T}}_0}^{\prime } $$ NNLL T 0 ′ +NNLO accuracy. This is the first implementation within the Geneva Monte Carlo framework of a process with a nontrivial Born-level definition which suffers from QED singularities. Throughout the computation we use a smooth-cone isolation algorithm to remove such divergences. The higher-order resummation of the 0-jettiness resolution variable $$ {\mathcal{T}}_0 $$ T 0 is based on a factorisation formula derived within Soft-Collinear Effective Theory which predicts all of the singular, virtual and real NNLO corrections. Starting from this precise parton-level prediction and by employing the Geneva method, we provide fully showered and hadronised events using Pythia8, while retaining the NNLO QCD accuracy for observables which are inclusive over the additional radiation. We compare our final predictions to LHC data at 7 TeV and find good agreement.
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39

Alioli, Simone, Alessandro Broggio, Alessandro Gavardi, Stefan Kallweit, Matthew A. Lim, Riccardo Nagar, Davide Napoletano et Luca Rottoli. « Resummed predictions for hadronic Higgs boson decays ». Journal of High Energy Physics 2021, no 4 (avril 2021). http://dx.doi.org/10.1007/jhep04(2021)254.

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Abstract We present the NNLL′ resummed 2-jettiness distribution for decays of the Standard Model Higgs boson to a b$$ \overline{b} $$ b ¯ -quark pair and to gluons. The calculation exploits a factorisation formula derived using Soft-Collinear Effective Theory, in which large logarithms of the 2-jettiness are resummed by renormalisation group evolution of the hard, soft and jet contributions to the differential decay rate. We match the resummed predictions to the fixed-order NNLO result using the Geneva framework, extending the validity of the results to all values of the resolution variable and providing a fully exclusive NNLO event generator matched to the Pythia8 parton shower.
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40

Lombardi, Daniele, Marius Wiesemann et Giulia Zanderighi. « Advancing MıNNLOPS to diboson processes : Zγ production at NNLO+PS ». Journal of High Energy Physics 2021, no 6 (juin 2021). http://dx.doi.org/10.1007/jhep06(2021)095.

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Abstract We consider Zγ production in hadronic collisions and present the first computation of next-to-next-to-leading order accurate predictions consistently matched to parton showers (NNLO+PS). Spin correlations, interferences and off-shell effects are included by calculating the full process pp → ℓ+ℓ−γ. We extend the recently developed MiNNLOPS method to genuine 2 → 2 hard scattering processes at the LHC, which paves the way for NNLO+PS simulations of all diboson processes. This is the first 2 → 2 NNLO+PS calculation that does not require an a-posteriori multi-differential reweighting. We find that both NNLO corrections and matching to parton showers are crucial for an accurate simulation of the Zγ process. Our predictions are in very good agreement with recent ATLAS data.
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41

Campbell, John, Tobias Neumann et Zack Sullivan. « Single-top-quark production in the t-channel at NNLO ». Journal of High Energy Physics 2021, no 2 (février 2021). http://dx.doi.org/10.1007/jhep02(2021)040.

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Abstract We present a calculation of t-channel single-top-quark production and decay in the five-flavor scheme at NNLO. Our results resolve a disagreement between two previous calculations of this process that found a difference in the inclusive cross section at the level of the NNLO coefficient itself. We compare in detail with the previous calculations at the inclusive, differential and fiducial level including b-quark tagging at a fixed scale μ = mt. In addition, we advocate the use of double deep inelastic scattering (DDIS) scales (μ2 = Q2 for the light-quark line and μ2 = Q2 + $$ {m}_t^2 $$ m t 2 for the heavy-quark line) that maximize perturbative stability and allow for robust scale uncertainties. All NNLO and NLO⊗NLO contributions for production and decay are included in the on-shell and vertex-function approximation. We present fiducial and differential results for a variety of observables used in Standard Model and Beyond Standard Model analyses, and find an important difference between the NLO and NNLO predictions of exclusive t + n-jet cross sections. Overall we find that NNLO corrections are crucial for a precise identification of the t-channel process.
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42

Mondini, Roberto, et Ciaran Williams. « Bottom-induced contributions to Higgs plus jet at next-to-next-to-leading order ». Journal of High Energy Physics 2021, no 5 (mai 2021). http://dx.doi.org/10.1007/jhep05(2021)045.

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Abstract We present a next-to-next-to-leading order (NNLO) QCD calculation of the bottom-induced contributions to the production of a Higgs boson plus a jet, i.e. the process pp → H + j to $$ \mathcal{O}\left({y}_b^2{\alpha}_s^3\right) $$ O y b 2 α s 3 . We work in the five-flavor scheme (5FS) in which the bottom quark mass is retained only in the coupling to the Higgs boson. Our calculation uses N-jettiness slicing to regulate infrared divergences, allowing for fully-differential predictions for collider observables. After extensively validating the methodology, we present results for the 13 TeV LHC. Our NNLO predictions show a marked improvement in the overall renormalization and factorization scale dependence, the latter of which proves to be particularly troublesome for 5FS calculations at lower orders. In addition, using the same methodology we present a NNLO computation of $$ b\overline{b} $$ b b ¯ → H. Our results are implemented into MCFM.
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43

Bell, Guido, Kevin Brune, Goutam Das et Marcel Wald. « The NNLO quark beam function for jet-veto resummation ». Journal of High Energy Physics 2023, no 1 (16 janvier 2023). http://dx.doi.org/10.1007/jhep01(2023)083.

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Abstract We consider the quark beam function that describes collinear initial-state radiation that is constrained by a veto on reconstructed jets. As the veto is imposed on the transverse momenta of the jets, the beam function is subject to rapidity divergences, and we use the collinear-anomaly framework to extract the perturbative matching kernels to next-to-next-to-leading order (NNLO) in the strong-coupling expansion. Our calculation is based on a novel framework that automates the computation of beam functions in Mellin space and it provides the ingredients to extend jet-veto resummations for quark-initiated processes to NNLL′ accuracy.
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44

Broggio, A., T. Engel, A. Ferroglia, M. K. Mandal, P. Mastrolia, M. Rocco, J. Ronca et al. « Muon-electron scattering at NNLO ». Journal of High Energy Physics 2023, no 1 (20 janvier 2023). http://dx.doi.org/10.1007/jhep01(2023)112.

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Abstract We present the first calculation of the complete set of NNLO QED corrections for muon-electron scattering. This includes leptonic, non-perturbative hadronic, and photonic contributions. All fermionic corrections as well as the photonic subset that only corrects the electron or the muon line are included with full mass dependence. The genuine four-point two-loop topologies are computed as an expansion in the small electron mass, taking into account both, logarithmically enhanced as well as constant mass effects using massification. A fast and stable implementation of the numerically delicate real-virtual contribution is achieved by combining OpenLoops with next-to-soft stabilisation. All matrix elements are implemented in the McMule framework, which allows for the fully-differential calculation of any infrared-safe observable. This calculation is to be viewed in the context of the MUonE experiment requiring a background prediction at the level of 10 ppm. Our results thus represent a major milestone towards this ambitious precision goal.
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45

Lombardi, Daniele, Marius Wiesemann et Giulia Zanderighi. « W+W− production at NNLO+PS with MINNLOPS ». Journal of High Energy Physics 2021, no 11 (novembre 2021). http://dx.doi.org/10.1007/jhep11(2021)230.

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Abstract We consider W+W− production in hadronic collisions and present the computation of next-to-next-to-leading order accurate predictions consistently matched to parton showers (NNLO+PS) using the MiNNLOPS method. Spin correlations, interferences and off-shell effects are included by calculating the full process pp → e+νeμ−$$ \overline{\nu} $$ ν ¯ μ. This is the first NNLO+PS calculation for W+W− production that does not require an a-posteriori multi-differential reweighting. The evaluation time of the two-loop contribution has been reduced by more than one order of magnitude through a four-dimensional cubic spline interpolation. We find good agreement with the inclusive and fiducial cross sections measured by ATLAS and CMS. Both NNLO corrections and matching to parton showers are important for an accurate simulation of the W+W− signal, and their matching provides the best description of fully exclusive W+W− events to date.
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46

Poncelet, Rene, et Andrei Popescu. « NNLO QCD study of polarised W+W− production at the LHC ». Journal of High Energy Physics 2021, no 7 (juillet 2021). http://dx.doi.org/10.1007/jhep07(2021)023.

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Abstract Longitudinal polarisation of the weak bosons is a direct consequence of Electroweak symmetry breaking mechanism providing an insight into its nature, and is instrumental in searches for physics beyond the Standard Model. We perform a polarisation study of the diboson production in the pp →$$ {\mathrm{e}}^{+}{v}_{\mathrm{e}}{\mu}^{-}{\overline{v}}_{\mu } $$ e + v e μ − v ¯ μ process at NNLO QCD in the fiducial setup inspired by experimental measurements at ATLAS. This is the first polarisation study at NNLO. We employ the double-pole approximation framework for the polarised calculation, and investigate NNLO effects arising in differential distributions.
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47

Sotnikov, Vasily. « Double Virtual Contributions for Massless 2 -> ; 3 Scattering in NNLO QCD ». SciPost Physics Proceedings, no 7 (20 juin 2022). http://dx.doi.org/10.21468/scipostphysproc.7.002.

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We review the recent advances in the calculation of two-loop QCD corrections for massless five-point scattering that paved the way for their broad phenomenological applications in calculation of NNLO QCD predictions. We first discuss the construction of a transcendental function basis which facilitates derivation of compact analytic representations for two-loop amplitudes and enables their fast and stable numerical evaluation over physical phase space. We then present the recent calculations of the leading-color two-loop corrections for hadroproduction of three photons and three jets.
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48

Chen, X., T. Gehrmann, E. W. N. Glover et J. Mo. « Antenna subtraction for jet production observables in full colour at NNLO ». Journal of High Energy Physics 2022, no 10 (6 octobre 2022). http://dx.doi.org/10.1007/jhep10(2022)040.

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Abstract We describe the details of the calculation of the full colour NNLO QCD corrections to jet production observables at the LHC with antenna subtraction. All relevant matrix elements for the process pp → jj at NNLO in full colour are colour-decomposed and given in a Nc and nf expansion, making identification of leading and subleading colour contributions transparent. The colour-ordered antenna subtraction method has previously successfully been used to construct the NNLO subtraction terms for processes with up to five partons or in the leading colour approximation. However, it is challenged by the more involved subleading colour structure of the squared matrix elements in processes with six or more partons. Here, we describe the methods needed to successfully construct the NNLO subtraction terms for the subleading colour contributions to dijet production within the antenna subtraction formalism.
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49

Czakon, Michał, Terry Generet, Alexander Mitov et Rene Poncelet. « B-hadron production in NNLO QCD : application to LHC t$$ \overline{t} $$ events with leptonic decays ». Journal of High Energy Physics 2021, no 10 (octobre 2021). http://dx.doi.org/10.1007/jhep10(2021)216.

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Abstract We calculate, for the first time, the NNLO QCD corrections to identified heavy hadron production at hadron colliders. The calculation is based on a flexible numeric framework which allows the calculation of any distribution of a single identified heavy hadron plus jets and non-QCD particles. As a first application we provide NNLO QCD predictions for several differential distributions of B hadrons in t$$ \overline{t} $$ t ¯ events at the LHC. Among others, these predictions are needed for the precise determination of the top quark mass. The extension of our results to other processes, like open or associated B and charm production is straightforward. We also explore the prospects for extracting heavy flavor fragmentation functions from LHC data.
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50

Chawdhry, Herschel A., Michał Czakon, Alexander Mitov et Rene Poncelet. « NNLO QCD corrections to diphoton production with an additional jet at the LHC ». Journal of High Energy Physics 2021, no 9 (septembre 2021). http://dx.doi.org/10.1007/jhep09(2021)093.

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Abstract We calculate the NNLO QCD corrections to diphoton production with an additional jet at the LHC. Our calculation represents the first NNLO-accurate prediction for the transverse momentum distribution of the diphoton system. The improvement in the accuracy of the theoretical prediction is significant, by a factor of up to four relative to NLO QCD as estimated through scale variations. Our calculation is exact except for the finite remainder of the two-loop amplitude which is included at leading color. The numerical impact of this approximated contribution is small. The results of this work are expected to further our understanding of the Higgs boson sector and of the behavior of higher-order corrections to LHC processes.
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