arXiv subjects

Adam Kardos

Publications and source records attributed to Adam Kardos.

At least 19 recordsLinked to original sources

arXiv2026

Design and performance of the Fast Beam Condition Monitor for luminosity and background measurement at the CMS Experiment in LHC Run 3

The Fast Beam Condition Monitor (BCM1F) has been used at the CMS Experiment since the first LHC circulating beams in 2008. Originally meant as a beam-induced background monitor for fast beam losses detection, it showed a potential also for luminosity measurements in 2012 running, and has been used for luminosity measurements since the beginning of Run 2 data taking in 2015 as a part of the Beam Radiation, Instrumentation and Luminosity (BRIL) system. Over the years, the system has undergone various upgrades to the sensors, the front-end and back-end electronics, providing improvements in the precision of the measurements, that remain valid in the higher pileup conditions of LHC Run 3 (2022-2026). Based on the experience of all BCM1F Run 2 upgrades, the detector was completely rebuilt prior to LHC Run 3 using AC-coupled silicon-pad diodes and active cooling. This latest detector version exhibits excellent linearity with instantaneous luminosity and achieves nanosecond-level timing precision, enabling improved systematic corrections for luminosity and background measurements. This paper presents a detailed overview of the detector system for LHC Run 3, including the selection and qualification of sensors as well as a summary of the readout system. It also outlines the processing and calibration strategy for luminosity data, discussing operational hurdles and comparing BCM1F measurements to other CMS luminosity measurements to assess the system's performance as a luminometer. Lastly, the implications for the design of a future luminosity detector to be used in the envisioned HL-LHC upgrade are discussed.

physics.ins-det↗

arXiv2026

HyperFORM -- a FORM package for parametric integration with hyperlogarithms

HyperFORM brings the parametric integration of hyperlogarithms, weighted by rational prefactors, into the symbolic-manipulation system FORM. It ports the capabilities of Erik Panzer's Maple package HyperInt, capitalizing on FORM's speed with bulky algebraic input and on its ability to spread a single calculation across many processor cores. We keep the description of the method brief and concentrate instead on how the package is organized and driven: a fully self-contained program for the three-loop zigzag period serves as a worked illustration, and timing measurements for zigzags through six loops gauge its present reach. HyperFORM is released openly and applies to a broad class of problems, the evaluation of Feynman integrals prominently among them.

hep-ph↗

arXiv2026

Heavy-quark pair-production in DIS at NLO QCD matched to a parton shower

We present theoretical predictions for heavy-quark pair-production in deep-inelastic scattering (DIS) at next-to-leading order (NLO) in quantum chromodynamics (QCD), matched to a parton shower in the POWHEG framework. We revisit the NLO heavy-quark pair-production cross section and implement a consistent matching to parton-shower evolution, with careful treatment of heavy-quark mass effects and the avoidance of double counting between fixed-order and parton-shower radiation. In addition, we compare the virtual NLO corrections available in the literature to one-loop amplitudes obtained through massification in the small-mass limit. This provides an independent validation of the virtual contributions. The study is presently restricted to the gluon-initiated channel, which dominates the kinematic region of interest at the HERA collider and remains important for the future Electron-Ion Collider.

hep-ph↗

arXiv2025

HyperFORM -- a FORM package for parametric integration with hyperlogarithms

We present an implementation of algorithms for the symbolic integration of hyperlogarithms multiplied by rational functions in the computer algebra system FORM. This implementation encompasses cases where hyperlogarithms have rational letters or a rational argument. It complements the previous implementation, HyperInt, in MAPLE by Erik Panzer, utilizing the advantages of FORM in the efficient handling of large symbolic expressions. Among a wide range of applications, this approach enables the computation of many Feynman integrals.

hep-ph↗

arXiv2024

LASS, the numerics

We summarize our efforts to create a numerical implementation of the Local Analytical Subtraction Scheme (LASS) for obtaining NNLO QCD predictions in electron-positron collisions. We focus on the regularization of double-real radiation contributions, which are typically the most computationally intensive part of NNLO calculations. We describe the structure of the subtraction terms in LASS and our approach to numerically validate them. Using arbitrary precision arithmetic, we demonstrate the proper convergence of individual subtraction terms, overlap removal terms, and spurious singularity cancellations in various singular limits. We show results for the specific case of three-jet production in $e^+e^-$ collisions. Our results validate the correctness of both the LASS formalism and our numerical implementation, setting the stage for full NNLO calculations using this method.

hep-ph↗

arXiv2024

Analysis of $(n+1)$ and $n$-parton contributions for computing QCD jet cross sections in the local analytic subtraction scheme

We analyze and implement the Local Analytic Sector Subtraction (LASS) scheme for handling infrared singularities in next-to-next-to-leading order (NNLO) calculations in perturbative QCD. We examine the key aspects of the scheme including sector function construction, singular limit parametrization, subtraction counterterm derivation, and integration techniques. As a proof-of-concept, we numerically implement LASS for the process $e^+e^- \rightarrow 3$ jets. In this study we examine the limiting behavior of subtraction terms for real-virtual contribution and explicitly demonstrate the pole cancellation of the double-virtual contribution. Differential cross sections are computed for several event shape observables, showing the stability and efficiency of LASS scheme. This work lays the foundation for developing an automated tool for NNLO QCD calculations using this promising scheme.

hep-ph↗

arXiv2022

Two-loop non-planar hexa-box integrals with one massive leg

Based on the Simplified Differential Equations approach, we present results for the two-loop non-planar hexa-box families of master integrals. We introduce a new approach to obtain the boundary terms and establish a one-dimensional integral representation of the master integrals in terms of Generalised Polylogarithms, when the alphabet contains non-factorisable square roots. The results are relevant to the study of NNLO QCD corrections for $W,Z$ and Higgs-boson production in association with two hadronic jets.

hep-ph↗

arXiv2021

Particle physics facing a pandemic

Our ordinary life changed quite a bit in March of 2020 due to the global Covid-19 pandemic. While spring time in general well awaited and regarded as a synonym for rejuvenation the spring of 2020 brought lock-down, curfew, home office and digital education to the lives of many. The particle physics community was not an exception: research institutes and universities introduced home office and digital lecturing and all workshops, conferences and summer schools were canceled, got postponed or took place online. Using publicly available data from the INSPIRE and arXiv databases we investigate the effects of this dramatic change of life to the publishing trends of the high-energy physics community with an emphasis on particle phenomenology and theory. To get insights we gather information about publishing trends in the last 20 years, and analyse it in detail.

physics.soc-ph↗

arXiv2021

Determination of $\alpha_{S}$ beyond $NNLO$ using the event shape averages

In this proceedings we discuss a prescription to extract the QCD strong coupling constant at $N^{3}LO$ precision in perturbative QCD using a combination of ${\cal{O}}(\alpha_{S}^{3})$ calculations in pQCD and estimations of the ${\cal{O}}(\alpha_{S}^{4})$ corrections from the data. The method is applied to a set of event shape averages measured in experiments at the LEP, PETRA, PEP and TRISTAN colliders. In our analysis we account for hadronization effects with models from modern Monte Carlo event generators and analytic hadronization models. We conclude that the precision of the $\alpha_{S}$ extraction cannot be improved significantly only with pQCD predictions of higher orders, and further progress in these studies requires a significant advances in the studies and modeling of hadronization process.

hep-ph↗

arXiv2020

Determination of $\alpha_{S}$ beyond NNLO using event shape averages

We consider a method for determining the QCD strong coupling constant using fits of perturbative predictions for event shape averages to data collected at the LEP, PETRA, PEP and TRISTAN colliders. To obtain highest accuracy predictions we use a combination of perturbative ${\cal{O}}(\alpha_{S}^{3})$ calculations and estimations of the ${\cal{O}}(\alpha_{S}^{4})$ perturbative coefficients from data. We account for non-perturbative effects using modern Monte Carlo event generators and analytic hadronization models. The obtained results show that the total precision of the $\alpha_{S}$ determination cannot be improved significantly with the higher order perturbative QCD corrections alone, but primarily requires a deeper understanding of the non-perturbative effects.

hep-ph↗

arXiv2020

Two- and Three-Loop Data for Groomed Jet Mass

We discuss the status of resummation of large logarithmic contributions to groomed event shapes of hadronic final states in electron-positron annihilation. We identify the missing ingredients needed for next-to-next-to-next-to-leading logarithmic (NNNLL) resummation of the mMDT groomed jet mass in $e^+e^-$ collisions: the low-scale collinear-soft constants at two-loop accuracy, $c_{S_c}^{(2)}$, and the three-loop non-cusp anomalous dimension of the global soft function, $\gamma_S^{(2)}$. We present a method for extracting those constants using fixed-order codes: the EVENT2 program to obtain the color coefficients of $c_{S_c}^{(2)}$, and MCCSM for extracting $\gamma_S^{(2)}$. We present all necessary formulae for resummation of the mMDT groomed heavy jet mass distribution at NNNLL accuracy.

hep-ph↗

arXiv2020

Groomed jet mass at high precision

We present predictions of the distribution of groomed heavy jet mass in electron-positron collisions at the next-to-next-to-leading order accuracy matched with the resummation of large logarithms to next-to-next-to-next-to-leading logarithmic accuracy. Resummation at this accuracy is possible through extraction of necessary two-loop constants and three-loop anomalous dimensions from fixed-order codes.

hep-ph↗

arXiv2019

High precision determination of $\alpha_s$ from a global fit of jet rates

We present state-of-the-art extractions of the strong coupling based on N$^3$LO+NNLL accurate predictions for the two-jet rate in the Durham clustering algorithm at $e^+e^-$ collisions, as well as a simultaneous fit of the two- and three-jet rates taking into account correlations between the two observables. The fits are performed on a large range of data sets collected at LEP and PETRA colliders, with energies spanning from $35$ GeV to $207$ GeV. Owing to the high accuracy of the predictions used, the perturbative uncertainty is considerably smaller than that due to hadronization. Our best determination at the $Z$ mass is $\alpha_s(M_Z) = 0.11881 \pm 0.00063(exp.) \pm 0.00101(hadr.) \pm 0.00045(ren.) \pm 0.00034(res.)$, which is in agreement with the latest world average and has a comparable total uncertainty.

hep-ph↗

arXiv2018

A new reduction strategy for special negative sectors of planar two-loop integrals without Laporta algorithm

In planar two-loop integrals there is a dedicated sector such that when its index is zero, the two-loop integral decomposes into the product of two one-loop integrals. We show an alternative reduction strategy for these sectors when their index is negative using the Baikov representation. This reduction strategy is free from the Laporta algorithm. It follows a top-down approach and is much faster than approaches based on the brute-force, conventional integration by parts identities.

hep-ph↗

arXiv2018

Soft-drop event shapes in electron-positron annihilation at next-to-next-to-leading order accuracy

We present predictions for soft-drop event shapes of hadronic final states in electron-positron annihilation at next-to-next-to-leading order accuracy in perturbation theory obtained using the CoLoRFulNNLO subtraction method. We study the impact of the soft drop on the convergence of the perturbative expansion for the distributions of three event shape variables, the soft-drop thrust, the hemisphere jet and narrow jet invariant masses. We find that grooming generally improves perturbative convergence for these event shapes. This better perturbative stability, in conjunction with a reduced sensitivity to non-perturbative hadronization corrections makes soft-drop event shapes promising observables for the precise determination of the strong coupling at lepton colliders.

hep-ph↗

arXiv2018

CoLoRFulNNLO for LHC processes

In my talk I gave a status update on the extension of the CoLoRFulNNLO subtraction method for computing QCD jet cross sections with hadrons in the initial state. The scheme has been fully worked out previously for electron-positron collisions and recently important steps have been made towards generalizing it to be able to deliver corrections of the same order for LHC processes as well. In particular, the important bottleneck of regularizing multiple real emissions has been addressed. We demonstrate the numerical stability of the CoLoRFulNNLO method by computing the doubly real contribution for Higgs-boson production in gluon-gluon fusion and for W production.

hep-ph↗

arXiv2018

Precise determination of $\alpha_{S}(M_Z)$ from a global fit of energy-energy correlation to NNLO+NNLL predictions

We present a comparison of the computation of energy-energy correlation in $e^{+}e^{-}$ collisions in the back-to-back region at next-to-next-to-leading logarithmic accuracy matched with the next-to-next-to-leading order perturbative prediction to LEP, PEP, PETRA, SLC and TRISTAN data. With these predictions we perform an extraction of the strong coupling constant taking into account non-perturbative effects modelled with Monte Carlo event generators. The final result at NNLO+NNLL precision is $\alpha_{S}(M_{Z})=0.11750\pm 0.00018 {\text( exp.)}\pm 0.00102{\text(hadr.)}\pm0.00257{\text(ren.)}\pm 0.00078{\text(res.)}$.

hep-ph↗

arXiv2017

Energy-energy correlation in electron-positron annihilation at NNLL+NNLO accuracy

We present the computation of energy-energy correlation in $e^+e^-$ collisions in the back-to-back region at next-to-next-to-leading logarithmic accuracy matched with the next-to-next-to-leading order perturbative prediction. We study the effect of the fixed higher order corrections in a comparison of our results to LEP and SLC data. The next-to-next-to-leading order correction has a sizable impact on the extracted value of $\alpha_{\mathrm S}(M_Z)$, hence its inclusion is mandatory for a precise measurement of the strong coupling using energy-energy correlation.

hep-ph↗