arXiv subjects

Scott A. Yost

Publications and source records attributed to Scott A. Yost.

15 recordsLinked to original sources

arXiv2026

Phenomenology of Matching Exponentiated Photonic Radiation to a Parton Shower in KKMChh

KKMChh adapts the soft photon exponentiation of the program KKMC, initially for electron-positron annihilation, to hadron collisions, where it must interface to a parton shower and parton distribution functions (PDFs) which may already include effects of QED radiation. We describe the NISR (Negative Initial State Radiation) algorithm developed to consistently interface with PDFs including QED effects, and present results on its effect on some distributions of phenomenological interest.

hep-ph↗

arXiv2026

Bhabha scattering at future colliders with BHLUMI/BHWIDE

In this paper, we briefly present the Monte Carlo event generators BHLUMI and BHWIDE for small and large angle Bhabha scattering, respectively, and discuss possible ways of their improvements in order to satisfy precision needs of future electron-positron colliders.

hep-ph↗

arXiv2024

KKMCee: Multi-photon MC for lepton and quark pair production at lepton colliders

We present an overview of the Monte Carlo event generator KKMCee for lepton and quark pair production in the high energy electron-positron annihilation process. We note that it is still the most sophisticated event generator for such processes. Its entire source code has been rewritten in C++. We have verified that the new version, KKMCee 5.00, reproduces the benchmarks of the older code in FORTRAN 77. We discuss a number of improvements in the MC algorithm and its interfaces.

hep-ph↗

arXiv2024

Phenomenology of matching exponentiated photonic radiation to a QED-corrected parton shower in KKMChh

KKMChh is a precision Monte Carlo program for photonic and electroweak radiative corrections to hadron scattering, implementing the amplitude-level exponentiation originally developed for electron-positron scattering at the quark level, modeling initial and final state QED radiation as well as initial-final interference to all orders in a soft-photon approximation, adding hard photon corrections through second order next-to-leading logarithm. A previous ICHEP talk introduced a matching procedure NISR (negative initial-state radiation) to match the exponentiated photon radiation from the quarks to a QED-corrected parton shower. Here, we describe its effect on forward-backward asymmetry calculations of interest for a precise determination of the electroweak mixing angle.

hep-ph↗

arXiv2020

KKMC-hh for Precision Electroweak Phenomenology at the LHC

We describe the program KKMC-hh, which calculates Z boson processes in hadronic collisions using coherent exclusive exponentiation (CEEX) with exact second-order photonic corrections at next-to-leading log and first-order weak vertex corrections, including initial and final state photonic radiation and initial-final interference. We describe current applications to precision forward-backward asymmetry calculations for the measurement of the electroweak mixing angle at the LHC.

hep-ph↗

arXiv2018

Recent IR-Improved results for LHC/FCC physics

We present recent developments in the theory and application of IR-improved QED$\otimes$QCD resummation methods, realized by MC event generator methods, for LHC and FCC physics scenarios.

hep-ph↗

arXiv2013

HERWIRI2: Exponentiated Electroweak Corrections in a Hadronic Event Generator

Reaching the desired precision level for W and Z processes at the LHC will require a mixture of higher-order QCD and electroweak corrections. HERWIRI2 is a step in implementing QED x QCD exponentiation in a hadronic event generator. This program implements leading electroweak corrections and coherent exclusive exponentiation in a HERWIG environment. We discuss the status of the program, recent tests, and future developments.

hep-ph↗

arXiv2010

Theoretical Uncertainties in Electroweak Boson Production Cross Sections at 7, 10, and 14 TeV at the LHC

We present an updated study of the systematic errors in the measurements of the electroweak boson cross-sections at the LHC for various experimental cuts for a center of mass energy of 7, 10 and 14 TeV. The size of both electroweak and NNLO QCD contributions are estimated, together with the systematic error from the parton distributions. The effects of new versions of the MSTW, CTEQ, and NNPDF PDFs are considered.

hep-ph↗

arXiv2008

Evaluation of the Theoretical Uncertainties in the W to Lepton and Neutrino Cross Sections at the LHC

We study the sources of systematic errors in the measurement of the W to lepton and neutrino cross-sections at the LHC. We consider the systematic errors in both the total cross-section and acceptance for anticipated experimental cuts. We include the best available analysis of QCD effects at NNLO in assessing the effect of higher order corrections and PDF and scale uncertainties on the theoretical acceptance. In addition, we evaluate the error due to missing NLO electroweak corrections and propose which MC generators and computational schemes should be implemented to best simulate the events.

hep-ph↗

arXiv2008

Evaluation of the Theoretical Uncertainties in the Z to ll Cross Sections at the LHC

We study the sources of systematic errors in the measurement of the Z to ll cross-sections at the LHC. We consider the systematic errors in both the total cross-section and acceptance for anticipated experimental cuts. We include the best available analysis of QCD effects at NNLO in assessing the effect of higher order corrections and PDF and scale uncertainties on the theoretical acceptance. In addition, we evaluate the error due to missing NLO electroweak corrections and propose which MC generators and computational schemes should be implemented to best simulate the events.

hep-ph↗

arXiv2006

Virtual Corrections to Bremsstrahlung in High-Energy Collider Physics: LHC and e+ e- Colliders

We describe radiative corrections to bremsstrahlung and their application to high energy collider physics, focusing on the applications to luminosity measurement, fermion pair production and radiative return. We review the status of one loop radiative corrections in BHLUMI and the KKMC, including cross checks with newer results developed independently for radiative return. We outline a YFS-exponentiated approach to the Drell-Yan process for LHC physics, including a discussion of the relevant radiative corrections.

hep-ph↗

arXiv2005

Radiative Corrections to Bremsstrahlung in Radiative Return

Radiating a photon from the initial state provides a useful tool for studying a range of low energy physics using a high-energy e+ e- accelerator. Accurate results require careful calculation of the first order virtual photon corrections. We compare exact results for initial state radiative corrections, finding agreement to an order of 10^{-5} or better as a fraction of the Born cross-section for most of the range of photon energies, at CMS energies relevant in both high-energy collision and radiative return experiments.

hep-ph↗

arXiv2004

Precision Electro-Weak and Hadronic Luminosity Calculations

We have used YFS Monte Carlo techniques to obtain per-mil level accuracy for the Bhabha scattering cross section used in the luminosity monitor in electro-weak scattering experiments. We will describe techniques for extending these methods for use in the W production luminosity cross section for hadron colliders.

hep-ph↗

arXiv1991

Charged Black Holes in Two-Dimensional String Theory

We discuss two dimensional string theories containing gauge fields introduced either via coupling to open strings, in which case we get a Born-Infeld type action, or via heterotic compactification. The solutions to the modified background field equations are charged black holes which exhibit interesting space-time geometries. We also compute their masses and charges.

hep-th↗

arXiv1991

Supermatrix Models

Random matrix models based on an integral over supermatrices are proposed as a natural extension of bosonic matrix models. The subtle nature of superspace integration allows these models to have very different properties from the analogous bosonic models. Two choices of integration slice are investigated. One leads to a perturbative structure which is reminiscent of, and perhaps identical to, the usual Hermitian matrix models. Another leads to an eigenvalue reduction which can be described by a two component plasma in one dimension. A stationary point of the model is described.

hep-th↗