On the treatment of resonances in next-to-leading order calculations matched to a parton shower

Abstract We propose a new approach for combining next-to-leading order (NLO) and parton shower (PS) calculations so as to obtain three core features: (a) applicability to general showers, as with the MC@NLO and POWHEG methods; (b) positive-weight events, as with the KrkNLO and POWHEG methods; and (c) all showering attributed to the parton shower code, as with the MC@NLO and KrkNLO methods. This is achieved by using multiplicative matching in phase space regions where the shower overestimates the matrix element and accumulative (additive) matching in regions where the shower underestimates the matrix element, an approach that can be viewed as a combination of the MC@NLO and KrkNLO methods.

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SIMULATION OF Z BOSON pT SPECTRUM AT TEVATRON BY LEADING-ORDER EVENT GENERATORS

Modern Physics Letters A ◽

10.1142/s0217732310034122 ◽

2010 ◽

Vol 25 (36) ◽

pp. 3047-3059 ◽

Cited By ~ 7

Author(s):

SHIGERU ODAKA

Keyword(s):

Transverse Momentum ◽

Z Boson ◽

Parton Shower ◽

Event Generator ◽

Boson Production ◽

Proper Solution ◽

Leading Order

We show that the transverse momentum (pT) spectrum of Z boson production measured at Fermilab Tevatron can be well reproduced by leading-order event generators if Z + 1 jet processes are included with a proper solution for the double-count problem and if the parton shower (PS) branch kinematics are defined appropriately. The choice of the PS evolution variable does not definitely determine the low-pT behavior. Our new event generator employing the limited leading-log (LLL) subtraction and a built-in leading-log PS reproduces the spectrum very well, not only in large pT regions but also at low pT down to pT = 0.

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Next-to-next-to-leading order event generation for Z-boson pair production matched to parton shower

Physics Letters B ◽

10.1016/j.physletb.2021.136380 ◽

2021 ◽

pp. 136380

Author(s):

Simone Alioli ◽

Alessandro Broggio ◽

Alessandro Gavardi ◽

Stefan Kallweit ◽

Matthew A. Lim ◽

...

Keyword(s):

Pair Production ◽

Z Boson ◽

Parton Shower ◽

Leading Order ◽

Boson Pair ◽

Boson Pair Production ◽

Event Generation

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Fixed-order and merged parton-shower predictions for WW and WWj production at the LHC including NLO QCD and EW corrections

Journal of High Energy Physics ◽

10.1007/jhep10(2020)159 ◽

2020 ◽

Vol 2020 (10) ◽

Author(s):

Stephan Bräuer ◽

Ansgar Denner ◽

Mathieu Pellen ◽

Marek Schönherr ◽

Steffen Schumann

Keyword(s):

Cross Sections ◽

Parton Shower ◽

Higher Order ◽

Order Effects ◽

Leading Order ◽

Combined Analysis ◽

Fixed Order ◽

Higher Order Effects ◽

Inclusive Sample ◽

Electroweak Corrections

Abstract First, we present a combined analysis of pp $$ \to {\mu}^{+}{v}_{\mu }{\mathrm{e}}^{-}{\overline{v}}_{\mathrm{e}} $$ → μ + v μ e − v ¯ e and pp $$ \to {\mu}^{+}{v}_{\mu }{\mathrm{e}}^{-}{\overline{v}}_{\mathrm{e}}\mathrm{j} $$ → μ + v μ e − v ¯ e j at next-to-leading order, including both QCD and electroweak corrections. Second, we provide all-order predictions for pp $$ \to {\mu}^{+}{v}_{\mu }{\mathrm{e}}^{-}{\overline{v}}_{\mathrm{e}}+ $$ → μ + v μ e − v ¯ e + jets using merged parton-shower simulations that also include approximate EW effects. A fully inclusive sample for WW production is compared to the fixed-order computations for exclusive zero- and one-jet selections. The various higher-order effects are studied in detail at the level of cross sections and differential distributions for realistic experimental set-ups. Our study confirms that merged predictions are significantly more stable than the fixed-order ones in particular regarding ratios between the two processes.

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