scholarly journals $${t {{\bar{t}}}H}$$ production at NNLO: the flavour off-diagonal channels

2021 ◽  
Vol 81 (6) ◽  
Author(s):  
Stefano Catani ◽  
Ignacio Fabre ◽  
Massimiliano Grazzini ◽  
Stefan Kallweit
Keyword(s):  
Transverse Momentum ◽  
Perturbative Expansion ◽  
Complete Agreement ◽  
Leading Order ◽  
Hadron Colliders ◽  
Fully Differential ◽  
Associated Production ◽  
Fixed Order ◽  
Heavy Quark Pair ◽  
First Time

AbstractWe consider QCD radiative corrections to the associated production of a heavy-quark pair ($$Q{{\bar{Q}}}$$ Q Q ¯ ) with a generic colourless system F at hadron colliders. We discuss the resummation formalism for the production of the $$Q{{\bar{Q}}}F$$ Q Q ¯ F system at small values of its total transverse momentum $$q_T$$ q T . We present the results of the corresponding resummation coefficients at next-to-leading and, partly, next-to-next-to-leading order. The perturbative expansion of the resummation formula leads to the explicit ingredients that can be used to apply the $$q_T$$ q T subtraction formalism to fixed-order calculations for this class of processes. We use the $$q_T$$ q T subtraction formalism to perform a fully differential perturbative computation for the production of a top-antitop quark pair and a Higgs boson. At next-to-leading order we compare our results with those obtained with established subtraction methods and we find complete agreement. We present, for the first time, the results for the flavour off-diagonal partonic channels at the next-to-next-to-leading order.

scholarly journals Transverse-momentum resummation for boson plus jet production at hadron colliders

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
Luca Buonocore ◽  
Massimiliano Grazzini ◽  
Jürg Haag ◽  
Luca Rottoli
Keyword(s):  
Higgs Boson ◽  
Transverse Momentum ◽  
Perturbative Expansion ◽  
Leading Order ◽  
Hadron Colliders ◽  
Azimuthal Correlations ◽  
Associated Production ◽  
Hadronic Collisions ◽  
Logarithmic Accuracy ◽  
Exact Dependence

AbstractWe consider the associated production of a vector or Higgs boson with a jet in hadronic collisions. When the transverse momentum $$q_T$$ q T of the boson-jet system is much smaller than its invariant mass Q, the QCD perturbative expansion is affected by large logarithmic terms that must be resummed to all orders. We discuss the all-order resummation structure of the logarithmically enhanced contributions up to next-to-leading logarithmic accuracy. Resummation is performed at the differential level with respect to the kinematical variables of the boson-jet system. Soft-parton radiation produces azimuthal correlations that are fully accounted for in our framework. We present explicit analytical results for the resummation coefficients up to next-to-leading order and next-to-leading logarithmic accuracy, that include the exact dependence on the jet radius.

scholarly journals Three-loop soft function for energetic electroweak boson production at hadron colliders

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Ze Long Liu ◽  
Maximilian Stahlhofen
Keyword(s):  
Transverse Momentum ◽  
Cross Sections ◽  
Hadron Collider ◽  
Boson Production ◽  
Leading Order ◽  
Large Transverse Momentum ◽  
Hadron Colliders ◽  
Soft Function ◽  
Electroweak Boson ◽  
First Time

Abstract We calculate the three-loop soft function for the production of an electroweak boson (Higgs, γ, W±, Z) with large transverse momentum at a hadron collider. It is the first time a soft function for a three-parton process is computed at next-to-next-to-next-to-leading order (N3LO). As a technical novelty, we perform the calculation in terms of forward-scattering-type loop diagrams rather than evaluating phase space integrals. Our three-loop result contains color-tripole contributions and explicitly confirms predictions on the universal infrared structure of QCD scattering amplitudes with three massless parton legs. The soft function is a central ingredient in the factorized cross section for electroweak boson production near the kinematic endpoint (threshold), where the invariant mass of the recoiling hadronic radiation is small compared to its transverse momentum. Our result is required for predictions of the near-threshold cross sections at N3LO and for the resummation of threshold logarithms at primed next-to-next-to-next-to-leading logarithmic (N3LL′) accuracy.

scholarly journals Next-to-leading-order QCD corrections and parton-shower effects for weakino+squark production at the LHC

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Julien Baglio ◽  
Gabriele Coniglio ◽  
Barbara Jäger ◽  
Michael Spira
Keyword(s):  
Production Process ◽  
Parton Shower ◽  
Leading Order ◽  
Hadron Colliders ◽  
Perturbative Calculations ◽  
The Real ◽  
Decay Products ◽  
Production Processes ◽  
Fixed Order ◽  
Real Emission

Abstract We present a calculation of the next-to-leading order QCD corrections to weakino+squark production processes at hadron colliders and their implementation in the framework of the POWHEG-BOX, a tool for the matching of fixed-order perturbative calculations with parton-shower programs. Particular care is taken in the subtraction of on-shell resonances in the real-emission corrections that have to be assigned to production processes of a different type. In order to illustrate the capabilities of our code, representative results are shown for selected SUSY parameter points in the pMSSM11. The perturbative stability of the calculation is assessed for the pp →$$ {\tilde{\upchi}}_1^0{\tilde{d}}_L $$ χ ˜ 1 0 d ˜ L process. For the squark+chargino production process pp →$$ {\upchi}_1^{-}{\tilde{u}}_L $$ χ 1 − u ˜ L distributions of the chargino’s decay products are provided with the help of the decay feature of PYTHIA 8.

scholarly journals Erratum: Diphoton Production at Hadron Colliders: A Fully Differential QCD Calculation at Next-to-Next-to-Leading Order [Phys. Rev. Lett.108, 072001 (2012)]

2016 ◽  
Vol 117 (8) ◽  
Author(s):  
Stefano Catani ◽  
Leandro Cieri ◽  
Daniel de Florian ◽  
Giancarlo Ferrera ◽  
Massimiliano Grazzini
Keyword(s):  
Leading Order ◽  
Hadron Colliders ◽  
Fully Differential

scholarly journals Jet angularities in Z+jet production at the LHC

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Simone Caletti ◽  
Oleh Fedkevych ◽  
Simone Marzani ◽  
Daniel Reichelt ◽  
Steffen Schumann ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Transverse Momentum ◽  
Parton Shower ◽  
Phenomenological Study ◽  
State Of The Art ◽  
Leading Order ◽  
Associate Production ◽  
Fixed Order ◽  
The Impact ◽  
Logarithmic Accuracy

Abstract We present a phenomenological study of angularities measured on the highest transverse-momentum jet in LHC events that feature the associate production of a Z boson and one or more jets. In particular, we study angularity distributions that are measured on jets with and without the SoftDrop grooming procedure. We begin our analysis exploiting state-of-the-art Monte Carlo parton shower simulations and we quantitatively assess the impact of next-to-leading order (NLO) matching and merging procedures. We then move to analytic resummation and arrive at an all-order expression that features the resummation of large logarithms at next-to-leading logarithmic accuracy (NLL) and is matched to the exact NLO result. Our predictions include the effect of soft emissions at large angles, treated as a power expansion in the jet radius, and non-global logarithms. Furthermore, matching to fixed-order is performed in such a way to ensure what is usually referred to as NLL′ accuracy. Our results account for realistic experimental cuts and can be easily compared to upcoming measurements of jet angularities from the LHC collaborations.

scholarly journals Diphoton Production at Hadron Colliders: A Fully Differential QCD Calculation at Next-to-Next-to-Leading Order

2012 ◽  
Vol 108 (7) ◽  
Author(s):  
Stefano Catani ◽  
Leandro Cieri ◽  
Daniel de Florian ◽  
Giancarlo Ferrera ◽  
Massimiliano Grazzini
Keyword(s):  
Leading Order ◽  
Hadron Colliders ◽  
Fully Differential

scholarly journals Associated production of gauginos and gluinos at hadron colliders in next-to-leading order SUSY-QCD

1999 ◽  
Vol 459 (1-3) ◽  
pp. 165-170 ◽  
Author(s):  
Edmond L Berger ◽  
Michael Klasen ◽  
Tim Tait
Keyword(s):  
Leading Order ◽  
Hadron Colliders ◽  
Associated Production

scholarly journals Bottom-quark production at hadron colliders: fully differential predictions in NNLO QCD

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Stefano Catani ◽  
Simone Devoto ◽  
Massimiliano Grazzini ◽  
Stefan Kallweit ◽  
Javier Mazzitelli
Keyword(s):  
Bottom Quark ◽  
Theoretical Description ◽  
Experimental Results ◽  
Radiative Corrections ◽  
Leading Order ◽  
Hadron Colliders ◽  
Quark Pairs ◽  
Fully Differential ◽  
Quark Production ◽  
Infrared Singularities

Abstract We report on the first fully differential calculation of the next-to-next-to-leading-order (NNLO) QCD radiative corrections to the production of bottom-quark pairs at hadron colliders. The calculation is performed by using the qT subtraction formalism to handle and cancel infrared singularities in real and virtual contributions. The computation is implemented in the Matrix framework, thereby allowing us to efficiently compute arbitrary infrared-safe observables in the four-flavour scheme. We present selected predictions for bottom-quark production at the Tevatron and at the LHC at different collider energies, and we perform some comparisons with available experimental results. We find that the NNLO corrections are sizeable, typically of the order of 25–35%, and they lead to a significant reduction of the perturbative uncertainties. Therefore, their inclusion is crucial for an accurate theoretical description of this process.

scholarly journals NNLO QCD corrections for Drell-Yan p ZT and $$ {\phi}_{{}^{\eta}}^{\ast } $$ observables at the LHC

2016 ◽  
Vol 2016 (11) ◽  
Author(s):  
A. Gehrmann-De Ridder ◽  
T. Gehrmann ◽  
E.W.N. Glover ◽  
A. Huss ◽  
T.A. Morgan
Keyword(s):  
Transverse Momentum ◽  
Cross Sections ◽  
Vector Boson ◽  
Substantial Improvement ◽  
Atlas Collaboration ◽  
Leading Order ◽  
Lepton Pairs ◽  
Approximate Relationship ◽  
Fixed Order ◽  
8 Tev

Abstract Drell-Yan lepton pairs with finite transverse momentum are produced when the vector boson recoils against (multiple) parton emission(s), and is determined by QCD dynamics. At small transverse momentum, the fixed order predictions break down due to the emergence of large logarithmic contributions. This region can be studied via the p T Z distribution constructed from the energies of the leptons, or through the $$ {\phi}_{{}^{\eta}}^{\ast } $$ ϕ η ∗ distribution that relies on the directions of the leptons. For sufficiently small transverse momentum, the $$ {\phi}_{{}^{\eta}}^{\ast } $$ ϕ η ∗ observable can be measured experimentally with better resolution. We study the small p T Z and $$ {\phi}_{{}^{\eta}}^{\ast } $$ ϕ η ∗ distributions up to next-to-next-to-leading order (NNLO) in perturbative QCD. We compute the $$ {\phi}_{{}^{\eta}}^{\ast } $$ ϕ η ∗ distributions for the fully inclusive production of lepton pairs via Z/γ∗ to NNLO and normalise them to the NNLO cross sections for inclusive Z/γ∗ production. We compare our predictions with the $$ {\phi}_{{}^{\eta}}^{\ast } $$ ϕ η ∗ distribution measured by the ATLAS collaboration during LHC operation at 8 TeV. We find that at moderate to large values of $$ {\phi}_{{}^{\eta}}^{\ast } $$ ϕ η ∗ , the NNLO effects are positive and lead to a substantial improvement in the theory-data comparison compared to next-to-leading order (NLO). At small values of p T Z and $$ {\phi}_{{}^{\eta}}^{\ast } $$ ϕ η ∗ , the known large logarithmic enhancements emerge through and we identify the region where resummation is needed. We find an approximate relationship between the values of p T Z and $$ {\phi}_{{}^{\eta}}^{\ast } $$ ϕ η ∗ where the large logarithms emerge and find perturbative consistency between the two observables.

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