arXiv subjects

Miroslav Myska

Publications and source records attributed to Miroslav Myska.

12 recordsLinked to original sources

arXiv2025

Herwig 7 with the Lund String Model: Tuning and Comparative Hadronization Studies

The modelling of the formation of colour-singlet hadrons from coloured partons, known as Hadronization, is crucial for generating realistic events in Monte Carlo Event Generators. Due to limited understanding of the non-perturbative regime, physically motivated phenomenological hadronization models with tunable parameters are used and later tuned to the experimental data. Modern Monte Carlo generators primarily employ one of two hadronization models: the Lund string model, which is the default in Pythia, and the cluster model, which is the default in Herwig and Sherpa. In this work, we combine the Lund string hadronization model, as implemented in Pythia 8, with Herwig 7 using TheP8I interface. We tune the string model with Herwig 7's Angular Ordered Parton Shower (AOPS) to lepton and hadron collision data, resulting in the Les Houches Tune (LH Tune), which shows good performance across a wide range of observables. The LH Tune will be included in the Herwig 7.4 release. This development enables a direct comparative study of the two hadronization models within Herwig, both interfaced with the Angular Ordered Parton Shower, which serves as the main motivation behind this work.

hep-ph↗

arXiv2020

Parton color reconnection in Herwig 7 using a spacetime event topology

Herwig 7 is a general-purpose Monte Carlo generator of particle collisions comprising both hard perturbative as well as soft phenomenological physics. Herwig is therefore capable to describe the entire final state of hadronized particles in a collision event. A spacetime topology of a parton system entering hadronization is fully described and tested for the first time. A combination of information from particles momenta and spacetime positions is utilized to minimize a boost-invariant distance measure of the parton system. We present a reasonable agreement of the model with a selection of experimental data and conclude that spacetime event topology can be meaningfully used in the further development.

hep-ph↗

arXiv2020

Confronting same-sign W-boson production with parton correlations

The future runs of LHC offer a unique opportunity to measure correlations between two partons inside the proton, which have never been experimentally detected. The process of interest is the production of two positively charged W-bosons decaying in the muon channel. We present a detailed analysis of proton-proton collisions at $\sqrt{s}$ = 13 TeV, where we combine Monte Carlo event generators with our calculations of parton correlations. We carefully compare double parton scattering to relevant background processes and trace a path towards a clean signal sample. Several observables are constructed to demonstrate the effect of parton correlations with respect to clear benchmark values for uncorrelated scatterings. We find that especially spin correlations can be responsible for large effects in the variables we study, because of their direct relation with the parton angular momentum and, therefore, the directions of the muon momenta. We estimate the significance of the measurements as a function of the integrated luminosity and conclude that the LHC has the potential to detect, or put strong limits on, parton correlations in the near future.

hep-ph↗

arXiv2019

Spacetime Colour Reconnection in Herwig 7

We present a model for generating spacetime coordinates in the Monte Carlo event generator Herwig 7, and perform colour reconnection by minimizing a boost-invariant distance measure of the system. We compare the model to a series of soft physics observables. We find reasonable agreement with the data, suggesting that $pp$-collider colour reconnection may be able to be applied in larger systems.

hep-ph↗

arXiv2019

A spin on same-sign W-boson pair production

We demonstrate that the LHC will be sensitive to quantum correlations between two quarks inside the proton. Same-sign W-boson pair production is the most promising channel for clear measurements of double parton scattering. The left-handed nature of the coupling between quarks and W-bosons makes it a prime probe to measure parton spin correlations. We perform a detailed analysis of double parton scattering, including relevant backgrounds. The analysis reveals that measurements comparing the rate at which two muons from W boson decays are produced in the same compared to opposite hemispheres are especially sensitive to spin correlations between two quarks inside the proton. We provide estimates of the significance of the measurements as a function of the integrated luminosity.

hep-ph↗

arXiv2016

Towards Diffraction in Herwig

We propose changes to the colour reconnection model in the Monte Carlo event generator Herwig in order to remove the quasi diffractive events from the soft multiple parton interactions. We then implement explicitly soft diffraction and show some preliminary results.

hep-ph↗

arXiv2013

Measurement of hard double-parton interactions with the ATLAS detector

The production of W boson in association with two jets in proton-proton collisions at the LHC with a centre-of-mass energy of $\sqrt{s}$ = 7 TeV has been investigated using data collected with the ATLAS detector. The fraction of events arising from double-parton scattering has been measured through the transverse momentum balance between the two jets. The measurement provides new information on the scaling of the rate of double-parton scattering processes and constraints on proton transverse profile modeling.

hep-ex↗

arXiv2013

Extracting sigma_effective from the CDF gamma+3jets measurement

In their 1997 paper, CDF measured sigma_effective, the normalization factor that relates the cross section for double parton scattering to the product of the inclusive cross sections of the two individual scatters, in a model in which they are assumed to be independent. In his 2007 paper, Treleani pointed out that CDF used a non-standard definition, in which the double parton scattering cross section corresponds to exactly two scatters, rather than the more conventional one in which it is the inclusive two-scatter cross section. He also estimated the correction from one definition to the other, to give a corrected value of sigma_effective. Treleani's form would be correct under the assumption that CDF were able to uniquely identify and count the number of scatters in an event, which is certainly not the case. In this publication we consider CDF's event definition in more detail to provide an improved correction.

hep-ph↗

arXiv2012

Searches for Double Parton Scattering at the LHC

Searches for the kinematic selection criteria for estimation of multiple parton interaction fraction in 14 TeV pp collisions are presented using the eikonalization of the cross section implemented in the Herwig++ Monte Carlo event generator. W+ boson pair production is studied in the muon decay channel. Four types of the main background processes are discussed and analyzed. These include W+W+ jj, W+Z, ZZ, and tt' productions of the positively charged muon pairs. The double parton scattering contribution to the requested di-muon final state is found to be around 25 per cent with the production cross section of 0.94 fb.

hep-ph↗

arXiv2012

Double Parton Scattering Contribution to pp -> W+W+

This study searches for the kinematic selection criteria for estimation of measurable MPI fraction in p-p collisions at \sqrt{s} = 14 TeV. The process under study is the Monte-Carlo production of pair of W+ gauge bosons decaying leptonically into a pair of same-sign muons. Specifically, the pseudo-rapidity asymmetry is evaluated in order to demonstrate the MPI behavior against the other physics background processes.

hep-ph↗

arXiv2012

Kinematical Signatures of W+ Pair Production

The underlying event measurement may be crucial for the new physics searches at high energies at LHC. This study presents the influence of double parton scattering on the same-sign di-muon production, where only the positive charge is taken into account for now. The signal production cross section is found to be 0.94 fb within the kinematic range of the ATLAS detector. This creates around 25 per cent of the total cross section for the searched final state.

hep-ex↗

arXiv2011

Study of Double Drell-Yan Process

This study focuses on the multiple parton scattering theory as a background for the new measurement of the inclusive cross section of the vector boson pair production at the LHC energies. The process under study is the double Drell-Yan annihilation. In this case, two quark-antiquark annihilations occur independently in one proton-proton annihilation. The final state with two pairs of leptons (electron or muon pair) is investigated while the intermedial vector boson can be both gamma and Z.

hep-ex↗