Polarized NLO EW [formula omitted] cross section calculations with ReneSANCe-v1.0.0

Renat Sadykov,Vitaly Yermolchyk

doi:10.1016/j.cpc.2020.107445

Renat Sadykov, Vitaly Yermolchyk

Open Access

https://doi.org/10.1016/j.cpc.2020.107445

Copy DOI

Abstract

In this paper we present a new Monte Carlo event generator ReneSANCe for simulation of processes at electron–positron colliders. In the current release of the generator the Bhabha scattering (e+e−→e−e+) and Higgs-strahlung (e+e−→ZH) process are implemented. Based on the SANC (Support for Analytic and Numeric Calculations for experiments at colliders) modules, the new generator takes into account complete one-loop and some higher-order electroweak radiative corrections with finite particle masses and polarizations. The new generator effectively operates in the collinear region and at the ZH production threshold. It is constructed in such a way that new processes can be easily added. The paper contains a theoretical description of the SANC approach, numerical validations and manual. Program summaryProgram Title: ReneSANCe-v1.0.0Program Files doi:http://dx.doi.org/10.17632/wp36f7t3ft.1Licensing provisions: GPLv3Programming language: Fortran, C, C++Supplementary material: Looptools [1], FOAM [2]Nature of problem: Theoretical calculations at next-to-leading order in perturbation theory allow to compute higher precision amplitudes for Standard Model processes and decays, provided proper treatments of UV divergences and IR singularities are performed.Solution method: Numerical integration of the precomputed differential expressions for cross sections of certain processes implemented as SANC modules [3,4].Restrictions: The list of processes is limited to e+e−→e−e+ and e+e−→ZH.

Highlights

The construction of high-precision theoretical predictions and their comparison with experimental data play a crucial role in solving the problem of applicability of the Standard Model and justifying its structure on the basis of fundamental principles
This paper describes the Monte Carlo event generator ReneSANCe (Renewed SANC Monte Carlo event generator), which provides a next-to-leading order (NLO) accurate electroweak (EW) description of some important processes at electron-positron colliders with respect to polarization effects
According to the SANC agreement, trivial integration over φ3 for the 2 → 2 processes and over φ5 for the 2 → 3 processes is performed in the corresponding module for the differential cross section, so we need to take it into account to prevent double counting

Summary

Introduction

The construction of high-precision theoretical predictions and their comparison with experimental data play a crucial role in solving the problem of applicability of the Standard Model and justifying its structure on the basis of fundamental principles. Monte Carlo event generators are used to account for detector effects in experimental data and obtain predictions with which these experimental data will be compared They can be used to obtain histograms of complex observables and pseudo-observables without rerunning and rewriting the code. An additional option of existing theoretical prediction tools should be the consideration of the beam polarization of future electron-positron accelerators Provided that both beams are polarized, experimental tests can be performed with unprecedented accuracy, either at the Z pole, or at the WW threshold, or at the peak of the ZH process, as well as at the ttthreshold. This paper describes the Monte Carlo event generator ReneSANCe (Renewed SANC Monte Carlo event generator), which provides a next-to-leading order (NLO) accurate electroweak (EW) description of some important processes at electron-positron colliders with respect to polarization effects.

NLO EW corrections with polarization in SANC framework

ReneSANCe structure

Configuration

Persistency

Numerical results