Fragmentation Uncertainties in Hadronic Observables for Top-quark Mass Measurements

Abstract

We study the Monte Carlo uncertainties due to modeling of hadronization and showering in the extraction of the top-quark mass from observables that use exclusive hadronic final states in top decays, such as $t\to \text{anything+J/}\psi$ or $t\to \text{anything}+(B\to \text{charged tracks})$, where $B$ is a $B$-hadron. To this end, we investigate the sensitivity of the top-quark mass, determined by means of a few observables already proposed in the literature as well as some new proposals, to the relevant parameters of event generators, such as HERWIG 6 and PYTHIA 8. We find that constraining those parameters at $\mathcal{O}(1\%-10\%)$ is required to avoid a Monte Carlo uncertainty on $m_t$ greater than 500 MeV. For the sake of achieving the needed accuracy on such parameters, we examine the sensitivity of the top-quark mass measured from spectral features, such as peaks, endpoints and distributions of $E_B$, $m_{B\ell }$, and some $m_{T2}$-like variables. We find that restricting oneself to regions sufficiently close to the endpoints enables one to substantially decrease the dependence on the Monte Carlo parameters, but at the price of inflating significantly the statistical uncertainties. To ameliorate this situation we study how well the data on top-quark production and decay at the LHC can be utilized to constrain the showering and hadronization variables. We find that a global exploration of several calibration observables, sensitive to the Monte Carlo parameters but very mildly to $m_t$, can offer useful constraints on the parameters, as long as such quantities are measured with a 1% precision.

35 pages, 9 figures, 11 tables

References in corpus (11)

• An Introduction to PYTHIA 8.2
• Using Subsystem MT2 for Complete Mass Determinations in Decay Chains with Missing Energy at Hadron Colliders
• An NLO+PS generator for $t\bar{t}$ and $Wt$ production and decay including non-resonant and interference effects
• Beyond Standard Model calculations with Sherpa
• Top Quark Mass Calibration for Monte Carlo Event Generators
• A study of the b-quark fragmentation function with the DELPHI detector at LEP I and an averaged distribution obtained at the Z Pole
• Measurement of the top quark mass with the template method in the top antitop -> lepton + jets channel using ATLAS data
• RECO level \sqrt{s}_{min} and subsystem \sqrt{s}_{min}: improved global inclusive variables for measuring the new physics mass scale in missing energy events at hadron colliders
• Measurement of the mass of the top quark in decays with a J/psi meson in pp collisions at 8 TeV
• Hadronization systematics and top mass reconstruction
• Top Quark Production and Decay in Herwig 7.1

Cited by in corpus (16)

• What is the Top Quark Mass?
• On the Cutoff Dependence of the Quark Mass Parameter in Angular Ordered Parton Showers
• A theoretical study of top-mass measurements at the LHC using NLO+PS generators of increasing accuracy
• Parton Shower and Matching Uncertainties in Top Quark Pair Production with Herwig 7
• Boosted Top Quarks in the Peak Region with N${}^3$LL Resummation
• Study of the underlying event in top quark pair production in pp collisions at 13 TeV
• NLO and off-shell effects in top quark mass determinations
• Top quark mass studies with $t\bar{t}j$ at the LHC
• Measurement of $b$-quark fragmentation properties in jets using the decay $B^{\pm }\to J/\psi K^{\pm }$ in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Measurement of the top-quark mass using a leptonic invariant mass in $pp$ collisions at $\sqrt{s}=13\text{TeV}$ with the ATLAS detector
• Towards a data-driven model of hadronization using normalizing flows
• Cutoff dependence of the thrust peak position in the dipole shower
• Single-top quark physics at the LHC: from precision measurements to rare processes and top quark properties
• Top-mass observables: all-orders behaviour, renormalons and NLO + Parton Shower effects
• The collider landscape: which collider for establishing the SM instability?
• Energy-peak based method to measure top quark mass via B-hadron decay lengths