Conveners
Nuclear, Particle and Radiation Physics-2
- Mpho Gololo (University of Johannesburg)
Nuclear, Particle and Radiation Physics-2
- Edward Nkadimeng (NRF-iThemba LABS)
Nuclear, Particle and Radiation Physics-2
- Edith Zinhle Buthelezi (NRF-iThemba LABS)
Nuclear, Particle and Radiation Physics-2
- Rachid Mazini (School of Physics and Institute for Collider Particle Physics, University of the Witwatersrand)
Nuclear, Particle and Radiation Physics-2
- Bruce Mellado Garcia (University of the Witwatersrand)
Nuclear, Particle and Radiation Physics-2
- Mukesh Kumar (University of the Witwatersrand)
Nuclear, Particle and Radiation Physics-2
- Mukesh Kumar (University of the Witwatersrand)
Nuclear, Particle and Radiation Physics-2
- Mpho Gololo (University of Johannesburg)
Nuclear, Particle and Radiation Physics-2
- Sifiso Ntshangase
- Mukesh Kumar (University of the Witwatersrand)
Nuclear, Particle and Radiation Physics-2
- Srimoy Bhattacharya (University of Witwatersrand)
Nuclear, Particle and Radiation Physics-2
- There are no conveners in this block
Edith Zinhle Buthelezi for the ALICE Collaboration
Heavy quarks or heavy flavours (charm and beauty) are produced mainly in initial hard-scattering processes of hadron-hadron collisions. Due to their large masses, their production cross sections are predicted via perturbative quantum chromodynamics (pQCD) models. They offer a unique perspective to study quark fragmentation and...
We compute the production spectra for high-momentum light quarks and gluons in high-energy hadron collisions at a variety of center-of-mass energies, some of which are previously unstudied. These spectra provide the foundation for making quantitative predictions of parton energy loss in high-multiplicity hadronic collisions at RHIC and the LHC. Thus these spectra are necessary in order to use...
While searches for physics beyond the Standard Model (BSM) have yet to yield conclusive discoveries, they continue to motivate the development of more flexible, data-driven strategies. At the ATLAS experiment at the Large Hadron Collider (LHC), trigger systems are used to rapidly select potentially interesting protonโproton collisions for further analysis. Traditional triggers rely on...
Precision luminosity measurements are crucial for determining the fundamental properties of physics processes at the Large Hadron Collider (LHC). In the ATLAS experiment, luminosity uncertainties often represent one of the leading sources of systematic uncertainty in cross-section measurements, directly impacting sensitivity to new physics searches and background estimations.
Since the...
The High-Luminosity Large Hadron Collider (HL-LHC) is scheduled to begin operation in 2030. While the increased luminosity presents exciting opportunities for new scientific discoveries, it also introduces significant technical challenges for the ATLAS detector systems. To meet these demands, the ATLAS Hadronic Tile Calorimeter (TileCal) will undergo a comprehensive Phase-II upgrade during the...
The Large Hadron Collider (LHC) is undergoing a high-luminosity upgrade to increase its luminosity, affecting the ATLAS detector and, consequently, its hadronic Tile-Calorimeter (TileCal). As part of the ATLAS Phase-II Upgrade to adapt to the new high-luminosity environment, the TileCal is upgrading its low-voltage power supplies (LVPS) that power its on-detector front-end (FE) electronics....
The performance and longevity of photomultiplier tubes in high-radiation environments, specifically the Tile Calorimeter, are crucial to the ATLAS detectorโs efficiency. This research is part of an ongoing investigation into the electron emission yield and electronic properties of various materials to be used in the dynode chain, the main component of the photomultiplier tubes. This study aims...
The ATLAS experiment at the High-Luminosity Large Hadron Collider (HL-LHC) will require advanced reconstruction techniques, particularly in the forward region, to cope with increased pile-up. This work presents a Particle Flow Algorithm (PFA) development for the ITk detector, focusing on tower clusters rather than traditional topological clusters in the ฮท = โจ0 โ 1.5โฉ region. The forward region...
The increase of the particle flux (pile-up) at the HL-LHC with instantaneous luminosity up to $L โ 7.5 ร 10^{34} cm^{โ2}.s^{โ1}$ will have a severe impact on the ATLAS detector reconstruction and trigger performance. The end-cap and forward region where the liquid Argon calorimeter has coarser granularity and the inner tracker has poorer momentum resolution will be particularly affected. A...
The High Granularity Timing Detector (HGTD) demonstrator was developed to validate the design and performance of its components. The setup included a printed circuit board (PEB), 54 modules, flex tails, a cooling system, and a data acquisition (DAQ) server. Tasks performed involved connecting flex tails, conducting alignment and I2C tests, and performing scanning tests to check bump...
Shortly after the Big Bang, the universe was in an incredibly hot and dense state, with particles moving at nearly the speed of light. During this brief period, lasting only a few microseconds, quarks and gluons were the dominant components. Due to the extremely high temperatures, these quarks and gluonsโcollectively known as partonsโwere only loosely bound and could move freely, forming a...
In recent years, the ``multilepton anomalies'' have emerged, consisting of several persistent tensions in channels with multiple electrons and/or muons in the final states, with missing transverse energy and ($b$-) jets. These anomalies have prompted growing interest in the possibility of a new scalar particle beyond the Standard Model (SM).
In this context, excesses have been observed in...
The statistical significance of the "multi-lepton anomalies"โthe discrepancies in the channels with multiple leptons, missing energy, and potentially ($b$)jets in the final states with the SM predictionโindicates the production of a scalar with a mass between 145 GeV and 155 GeV that is beyond the standard model. The associated production of a narrow scalar resonance of mass $\approx$ 152...
We investigate the anomalous tt̅X couplings for neutral charged gauge boson X=Z/γ in the Standard Model (SM) and measure their precision beyond the SM in future electron-proton collider environments. The tt̅ quark pairs are produced in the neutral currents channel through the process e- p → e- t t̅ , for electron...
Recent studies (arXiv:2109.02650, 2306.17209, 2503.16245) have identified growing excesses in scalar resonances with di-photon at the Large Hadron Collider (LHC), suggesting the presence of scalar particles beyond the Standard Model. These scalar resonances are motivated by the multi-lepton anomalies at the LHC which indicate a potential new scalar particle $S$ with a mass of approximately...
A Monte Carlo generation campaign has been submitted under the HBSM subgroup to study a simplified model featuring the resonant production of scalar particles at the electroweak scale. The process under consideration is $ gg \rightarrow H \rightarrow SS' $, where the scalar $ S $ (with a mass of approximately 150 GeV) decays to a diphoton final state $( \gamma\gamma )$, and the accompanying...
Searches for di-photon resonances at the ATLAS experiment have primarily focused on the mass range of $200$โ$3000\,\mathrm{GeV}$. However, phenomenological studies based on Run 1 data have reported excesses-commonly referred to as multi-lepton anomalies-suggesting the possible existence of a scalar resonance with a mass of $150 \pm 5\,\mathrm{GeV}$. Further investigations of $\gamma\gamma$ ...
The search for new scalar resonances at the Large Hadron Collider (LHC) is motivated by beyond the Standard Model (BSM) scenarios such as the Two-Higgs-Doublet Model with an additional scalar singlet (2HDM+S) and the Real Higgs Triplet Model. The 2HDM+S and Triplet model BSM frameworks is being used to study new scalar particles that may decay into final states involving photons and leptons....
The Multi-lepton anomalies at the LHC are indicative of a scalar resonance with a mass around $150 \pm 5$\,GeV in the $\gamma \gamma$ and $Z \gamma$ spectra in association with leptons and jets with a global significance of $5.4 \sigma$. This provides a compelling avenue for exploring new physics beyond the Standard Model using the di-photon channel. This project investigates the hypothesized...
The field of collider particle physics is at a pivotal juncture, with global debates intensifying over the direction of future accelerators and large-scale international collaborations. As the scientific landscape continues to evolve, it is imperative for the global particle physics community to refine its strategic priorities and align around shared goals. The European Strategy for Particle...
The European Strategy for Particle Physics stimulated the preparation of the European Detector Roadmap document in 2021 by the European Committee for Future Accelerators ECFA. This roadmap, defined during a bottom-up process by the community, outlines nine technology domains for HEP instrumentation and pinpoints urgent R&D topics, known as Detector R&D Themes (DRDTs). Task forces were set for...
An extraction of the top quark Yukawa coupling ($Y_{t}$) from top quark pair production is presented using proton-proton collisions at $\sqrt{s} = $ 13 TeV, corresponding to an integrated luminosity of 140 $fb^{-1}$, recorded by the ATLAS experiment. Corrections from a Higgs boson exchange between the top quark and top anti-quark can produce non-negligible modifications to differential...
The $tWZ$ production is a rare and unobserved Standard Model process which refers to the production of a single top quark with an associated W boson and Z boson. The $tWZ$ process is sensitive to top-electroweak couplings and thus it will be an important input into global Standard Model Effective Field Theory (SMEFT) fits. Additionally, this process can be used as a background in other top...
The top quark, the heaviest known elementary particle ($m_t \approx 172.52\,$GeV), plays a crucial role in probing the Standard Model (SM) at high energies. At the Large Hadron Collider (LHC), top quark pair production ($t\bar{t}$) is the dominant mechanism for top production. The top quark predominantly decays to a $b$-quark and a $W^+$ boson, the latter of which decays either leptonically or...
Many extensions to the Standard Model (SM) introduce a hidden or a dark sector rising from an additional $U(1)_d$ gauge symmetry, to provide candidates for dark matter in the universe and a possible explanation to astrophysical observations such as the positron excess observed in the cosmic radiation flux. The gauge boson of the dark sector would be either a massless or a massive dark photon...
Given the discovery of the Standard Model Higgs boson in 2012 by both ATLAS and CMS experiments at the Large Hardon Collider at CERN, further properties of the Higgs boson are important to be explored. The search for Higgs decaying to invisible particles is a potential portal to look for physics beyond the Standard Model. Among all Higgs production channels at the LHC, vector boson fusion...
We present a search for a spin-1 boson together with a spin-0 scalar wherer the additional scalar decays into a four lepton final state $(\ell = \mu$~or $e )$ via two intermediate dark vector bosons in the folllowing decay channel $S \rightarrow Z_d Z_d \rightarrow 4\ell$. In this scenario, the targeted additional scalar ($S$) mass ranges is between 20 GeV and 1 TeV where we exclude the Higgs...
The charged vector boson (W$^\pm$) is produced in the hard partonic scattering of relativistic hadronic collisions, where its production cross-section can be calculated theoretically from perturbation theory and the relevant hadronic parton distribution functions (PDFs). Since it does not interact strongly and decays leptonically, the W boson serves as an ideal probe of the initial state of...
The lepton flavor universality ratios $R(D)$ and $R(D^{*})$, defined as $R_{D^{(*)}} \equiv \mathcal{B}(\bar{B}\to D^{(*)} \tau^{-} \bar{\nu}_{\tau})/\mathcal{B}(\bar{B} \to D^{(*)} \ell^{-} \bar{\nu}_{\ell})$ where$(\ell = e, \mu)$, are measured in semi-leptonic $B$ decays and serve as sensitive probes of new physics beyond the Standard Model (SM). Recent experimental averages, $R(D) = 0.342...
The ATLAS and CMS collaborations have jointly reported the first evidence of the Higgs boson ($h$) decay into a $Z$ boson and a photon, with a statistical significance of $3.4\sigma$. The observed signal strength, $2.2 \pm 0.7$ times the Standard Model (SM) expectation, exceeds the SM prediction even when next-to-leading order (NLO) QCD corrections and signal-background interference are taken...
Building on the ATLAS and CMS discovery of the Higgs boson decaying into a $Z$-boson and a photon (with a 3.4$\sigma$ significance), the current Standard Model (SM) predictions for the $h \to Z\gamma$ signal rate exceed the measured value by $2.4 \pm 0.9$, indicating possible new physics effects or systematic uncertainties that warrant further investigation. This analysis investigates this...
Monte Carlo (MC) simulated data are essential for modeling events in the ATLAS Inner Detector. However, full Geant4-based simulations have become increasingly computationally demanding, with approximately 80% of the processing time attributed to shower simulation and detailed ATLAS detector geometry modeling. To address this, the new ATLAS Fast Simulation (AF3) framework provides a...
The hidden abelian Higgs model is used for a search for an additional scalar decaying to two Z-dark bosons (Zd) to two leptons, two neutrinos (2l2v) . The search uses ๐๐ collision data collected with the ATLAS detector at the LHC with an integrated luminosity of 139 fbโปยน at a centre-of-mass energy โs= 13 TeV . This is a follow up to the study of the 4l final states [1]. In our 2l2v channel...
