Publications

Order by: publication date number of citations

• Sub-TeV hadronic interaction model differences and their impact on air showers

  Michael Schmelling, Álvaro Pastor-Gutiérrez, Harm Schorlemmer, Robert Daniel Parsons

  SciPost Phys. Proc. 15, 015 (2024) · published 2 April 2024 | Toggle abstract · pdf

  In the sub-TeV regime, the most widely used hadronic interaction models disagree significantly in their predictions of particle spectra from cosmic ray induced air showers. We investigate the nature and impact of model uncertainties, focussing on air shower primaries with energies around the transition between high and low energy hadronic interaction models, where the dissimilarities are largest and which constitute the bulk of the interactions in air showers.

• The role of the underlying event in the charm-baryon enhancement observed in pp collisions at LHC energies

  Zoltán Varga, Anett Misák, Róbert Vértesi

  SciPost Phys. Proc. 15, 014 (2024) · published 2 April 2024 | Toggle abstract · pdf

  We study the enhanced production of $\Lambda_c$ charmed baryons relative to that of charmed $D^0$ mesons in proton–proton collisions at LHC energies. We simulated collision events with the enhanced color-reconnection model in PYTHIA 8 MC generator and propose measurements based on the comparative use of different event-activity classifiers to identify the source of the charmed-baryon enhancement. We demonstrate that in this enhanced color-reconnection scenario the excess production is primarily linked to the underlying event and not to the production of high-momentum jets.

• ATLAS results on exotic hadronic resonances

  Yue Xu

  SciPost Phys. Proc. 15, 013 (2024) · published 2 April 2024 | Toggle abstract · pdf

  Recent results from the proton-proton collision data taken by the ATLAS experiment on exotic resonances are presented. A search for $J/\psi p$ resonances in $\Lambda_{b}→ J/\psi p K$ decays with large $p K$ invariant masses is reported. A search for exotic resonances in the four-muon final state is shown.

• Intermittency analysis of charged hadrons generated in Pb-Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV and 5.02 TeV

  Salman Khurshid Malik, Ramni Gupta

  SciPost Phys. Proc. 15, 012 (2024) · published 2 April 2024 | Toggle abstract · pdf

  Local density fluctuations are expected to scale as a universal power-law when the system approaches critical point. Such power-law fluctuations are studied within the framework of intermittency through the measurement of normalized factorial moments in ($\eta$, $\phi$) phase space. Observations and results from the intermittency analysis performed for charged particles in Pb-Pb collisions using PYTHIA8/Angantyr at 2.76 TeV and 5.02 TeV are reported. We observe no scaling behaviour in the particle generation for any of the centrality studied in narrow p$_T$ bins. The scaling exponent $\nu$ shows no dependence on the centrality ranges.

• Recent ATLAS results on forward physics and diffraction

  Rafał Staszewski

  SciPost Phys. Proc. 15, 011 (2024) · published 2 April 2024 | Toggle abstract · pdf

  The ATLAS detector at the LHC is equipped with dedicated systems designed for the detection of forward protons produced in diffractive and photon-induced processes. These detectors significantly extend the ATLAS physics reach. Recent measurements performed using these forward proton detectors: elastic proton-proton scattering, exclusive charged pion-pair production, and two-photon production of lepton pairs are presented.

• Intermittency analysis of charged particles generated in Xe-Xe~collisions at $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV using the AMPT model

  Zarina Banoo, Ramni Gupta

  SciPost Phys. Proc. 15, 010 (2024) · published 2 April 2024 | Toggle abstract · pdf

  The multiplicity fluctuations are sensitive to QCD phase transition and to the presence of critical point in QCD phase diagram. At critical point a system undergoing phase transition is characterized by large fluctuations in the observables which is an important tool to understand the dynamics of particle production in heavy-ion interactions and phase changes. Multiplicity fluctuations of produced particles is an important observable to characterize the evolving system. Using scaling exponent obtained from the normalized factorial moments of the number of charged hadrons in the two dimensional ($\eta,\phi$) phase space, one can learn about the dynamics of system created in these collisions. Events generated using Xe-Xe collisions at $\sqrt{s_{\rm{NN}}} = 5.44 $ TeV with string-melting (SM) version of the AMPT model are analyzed and the scaling exponent $(\nu)$ for various $p_T$ intervals is determined. It is observed that the calculated value of $\nu$ is larger than the universal value 1.304, as is obtained from Ginzburg-Landau theory for second order phase transition. Here we will also present the results of the dependence of the scaling exponent on the transverse momentum bin width.

• Recent LHCb results on forward physics and diffraction

  Luke McConnell

  SciPost Phys. Proc. 15, 009 (2024) · published 2 April 2024 | Toggle abstract · pdf

  The LHCb detector at the LHC offers unique coverage of forward rapidities for studies of Central Exclusive Production (CEP) and soft QCD. CEP measurements allow the investigation of the nature of pomerons, and provide constraints on low-x gluon phenomenology, probing potential saturation effects. Moreover LHCb can test phenomenological models of soft QCD processes, by measuring the production of forward hadrons in pp collisions. In this talk the latest results from the LHCb experiment will be presented.

• Forward proton measurements with ATLAS

  Mustafa Schmidt

  SciPost Phys. Proc. 15, 008 (2024) · published 2 April 2024 | Toggle abstract · pdf

  The ALFA subdetector is designed to measure elastic proton-proton scattering from which the total cross section and $\rho$-parameter are determined. In 2016, special runs at a center-of-mass energy of $\sqrt{s}$ = 13 TeV and with $\beta^\star$ = 2.5 km were recorded.

• Amplitude and colour evolution

  Simon Plätzer

  SciPost Phys. Proc. 15, 007 (2024) · published 2 April 2024 | Toggle abstract · pdf

  Colour evolution and parton branching at the amplitude level have become important theoretical frameworks to improve parton showers, and are algorithms in their own right: They complement shower development by resummation algorithms capable of including interference effects and subleading colour contributions at an unprecedented level. I summarize recent development in the field, focusing on soft gluon evolution, hadronization, and the CVolver framework.

• Towards better discrimination and improved modelling of dark-sector showers

  Andy Buckley, Deepak Kar, Sukanya Sinha

  SciPost Phys. Proc. 15, 006 (2024) · published 2 April 2024 | Toggle abstract · pdf

  As no evidence for classic WIMP-based signatures of dark matter have been found at the LHC, several phenomenological studies have raised the possibility of accessing a strongly-interacting dark sector through new collider-event topologies. If dark mesons exist, their evolution and hadronization procedure are currently little constrained. They could decay promptly and result in QCD-like jet structures, even though the original decaying particles are dark sector ones; they could behave as semi-visible jets; or they could behave as completely detector-stable hadrons, in which case the final state is just the missing transverse momentum. In this contribution we will introduce a study performed to explore use of jet substructure methods to distinguish dark-sector from QCD jets in the first two scenarios, using observables in a IRC-safe linear basis, and discuss ways forward for this approach to dark-matter at the LHC.