Voice of Science event "Particle Physics Engagement in Edinburgh: from Peter Higgs Legacy to LEGO and boardgames" with Jean-Christophe Denis

The CERN Library organises talks centred around science communication featuring renowned speakers who share their experience and insights into making complex scientific ideas accessible and engaging for all. The 4th talk was given by Dr Jean-Christophe Denis on "Particle Physics Engagement in Edinburgh: from Peter Higgs Legacy to LEGO and boardgames": https://indico.cern.ch/event/1501291

First kTk_{\mathrm{T}} scan of the Lund jet plane in heavy-ion collisions to test the factorization of the vacuum and medium parton shower

This note presents the first relative transverse momentum ($k_{\mathrm{T}}$) scan of the Lund jet plane for high-energy jets in lead-lead (Pb-Pb) collisions at the LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. We report the fully corrected angular distribution of the primary emissions with the highest $k_{\mathrm{T}}$ in two different ranges of $k_{\mathrm{T}}$ for anti-$k_{\mathrm{T}}$ jets with distance parameter $R=0.4$ and transverse momentum in the range $200 < p_{\mathrm{T}}^\text{jet} < 1000$ GeV. The analysis uses Pb-Pb and pp data samples with integrated luminosities of $1.7\,\text{nb}^{-1}$ and $301\,\text{pb}^{-1}$, respectively, collected with the CMS experiment in 2018 and 2017. A $k_{\mathrm{T}}$ scan of the Lund plane allows us to explore the scale dependence of jet quenching phenomena. Our measurement was designed to test the validity of the assumed factorization between the early vacuum and QGP-induced stages of jet evolution in heavy-ion collisions, which is an underlying assumption of several jet quenching models and has not yet been experimentally proven. The reported angular distribution of emissions at high $k_{\mathrm{T}}$ have a similar shape in pp and Pb-Pb, and this is consistent with the emissions being part of the early and vacuum-like regime of the jet evolution in Pb-Pb

Multiplicity dependence of f0(980)\mathbf{{\rm f}_{0}(980)} production in pp collisions at s=\mathbf{\sqrt{s}}= 13 TeV

The dependence of $\mathrm{f}_{0}$(980) production on the final-state charged-particle multiplicity is reported for proton--proton (pp) collisions at the centre-of-mass energy, $\sqrt{s}=$ 13 TeV. The production of $\mathrm{f}_{0}$(980) is measured with the ALICE detector via the $\mathrm{f}_0 (980) \rightarrow \pi^{+}\pi^{-}$ decay channel in a midrapidity region of $|y|<$~0.5. The evolution of the integrated yields and mean transverse momentum of f$_{0}$(980) as a function of charged-particle multiplicity measured in pp at $\sqrt{s}=$ 13 TeV follows the trends observed in pp at $\sqrt{s}=$ 5.02 TeV and in proton--lead (p--Pb) collisions at $\sqrt{s_{\rm{NN}}}=$ 5.02 TeV. Particle yield ratios of $\mathrm{f}_{0}$(980) to $\pi^{\pm}$ and $\mathrm{K}^{*}$(892)$^{0}$ are found to decrease with increasing charged-particle multiplicity. These particle ratios are compared with calculations from the canonical statistical thermal model as a function of charged-particle multiplicity. The thermal model calculations provide a better description of the decreasing trend of particle ratios when no strange or antistrange quark composition for f$_{0}$(980) is assumed, which suggests that the tetraquark interpretation of the f$_{0}$(980) is disfavored.The dependence of f$_0$(980) production on the final-state charged-particle multiplicity is reported for proton-proton (pp) collisions at the centre-of-mass energy, $\sqrt{s}= 13$ TeV. The production of f$_0$(980) is measured with the ALICE detector via the f$_0(980) \rightarrow π^{+}π^{-}$ decay channel in a midrapidity region of $|y| < 0.5$. The evolution of the integrated yields and mean transverse momentum of f$_{0}$(980) as a function of charged-particle multiplicity measured in pp at $\sqrt{s} = 13$ TeV follows the trends observed in pp at $\sqrt{s} = 5.02$ TeV and in proton-lead (p-Pb) collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV. Particle yield ratios of f$_{0}$(980) to $π^{\pm}$ and K$^{*}$(892)$^{0}$ are found to decrease with increasing charged-particle multiplicity. These particle ratios are compared with calculations from the canonical statistical thermal model as a function of charged-particle multiplicity. The thermal model calculations provide a better description of the decreasing trend of particle ratios when no strange or antistrange quark composition for f$_{0}$(980) is assumed, which suggests that the tetraquark interpretation of the f$_{0}$(980) is disfavored

Energy efficiency trends in HPC: what high-energy and astrophysicists need to know

The growing energy demands of HPC systems have made energy efficiency a critical concern for system developers and operators. However, HPC users are generally less aware of how these energy concerns influence the design, deployment, and operation of supercomputers even though they experience the consequences. This paper examines the implications of HPC's energy consumption, providing an overview of current trends aimed at improving energy efficiency. We describe how hardware innovations such as energy-efficient processors, novel system architectures, power management techniques, and advanced scheduling policies do have a direct impact on how applications need to be programmed and executed on HPC systems. For application developers, understanding how these new systems work and how to analyse and report the performances of their own software is critical in the dialog with HPC system designers and administrators. The paper aims to raise awareness about energy efficiency among users, particularly in the high energy physics and astrophysics domains, offering practical advice on how to analyse and optimise applications to reduce their energy consumption without compromising on performance

Searches for exotic particles in multileptonic final states with the ATLAS detector using full Run-2 data

Over the past years, the need for an extension of the Standard Model (SM) has become more and more clear, so high-energy physics experiments must explore Beyond the SM (BSM) scenarios, which now constitute an important part of the ATLAS experiment physics program. Searches for multileptonic final states have favourable signatures thanks to the low number of SM processes procuding events with high lepton multiplicity, as these would worsen the signalto- background ratio. In the context of Left-Right Symmetric Model (LRSM) and the Type-III See-Saw mechanism, New Physics events are searched for in several processes, like the production of doubly charged Higgs bosons and the production of heavy neutral or charged leptons. The final states investigated can also involve same-sign light leptons, allowing lepton-number-violation foreseen by the LRSM. ATLAS BSM searches exploring these scenarios with full LHC Run-2 data, for a total luminosity of 139 fb$^-1$ at a centre-of-mass energy of $\sqrt{s}$= 13TeV in $pp$ collisions, are here presented

Recent Higgs measurements at the ATLAS experiment

The precise measurement of Higgs boson production and decay at the LHC continues to be a central tool for testing the Standard Model (SM) and looking for signs of new physics. This talk presents a comprehensive overview of recent Higgs boson measurements performed by the ATLAS experiment, using data from Run 2 and partial Run 3 of proton-proton collisions at center-of-mass energies of 13 TeV and 13.6 TeV. Highlights include differential and inclusive cross-section measurements, studies of different production modes and measurements of Higgs coupling to heavy quarks. In addition, recent results on Higgs boson pair production provide valuable input for probing the Higgs self-coupling. These measurements and the innovative techniques used represent key steps in deepening our understanding of the Higgs sector and offer potential windows into physics beyond the Standard Model

Backtracking AdS flux vacua

We introduce an algorithm (dubbed "flux backtracking") to reverse-engineer the brane picture from an AdS flux vacuum. Given an AdS flux vacuum as input, the algorithm outputs a singularity in 10 or 11 dimensions. This singularity has the property that when probed with the appropriate stack of branes (and after taking the near-horizon limit), one recovers the initial AdS vacuum. After testing the procedure on a number of known AdS/CFT pairs, we apply it to AdS flux vacua without known holographic dual, notably the scale-separated DGKT solution. In this case, flux backtracking produces a certain strongly coupled singularity in massive IIA; we conjecture that the worldvolume CFT of D4-branes probing this singularity should be the holographic CFT dual to DGKT (if it exists). Applying the procedure to the DGKT-related scale-separated AdS$_4$ solutions without Romans mass, we find instead a conical and weakly coupled singularity. We also comment on the results and limitations of applying the procedure to KKLT

Classifying hadronic objects in ATLAS with ML/AI algorithms

Hadronic object reconstruction & classification is one of the most promising settings for cutting-edge machine learning and artificial intelligence algorithms at the LHC. In this contribution, highlights of ML/AI applications by ATLAS to QCD/boosted-object identification and quark/gluon identification will be presented

CP violation in K→μ+μ−K\toμ^+μ^- with and without time dependence through a tagged analysis

We point out that using current knowledge of ${\cal B}(K^0_L\toμ^+μ^-)$ and ${\cal B}(K^0_L\to γγ)$, one can extract short-distance information from the combined measurement of the time-integrated CP asymmetry, $A_{\rm CP}(K^0\toμ^+μ^-)$, and of ${\cal B}(K^0_S\toμ^+μ^-)$. We discuss the interplay between this set of observables, and demonstrate that determining ${\rm sign}[A_{\rm CP}(K^0\toμ^+μ^-)]$ would eliminate the discrete ambiguity in the Standard Model prediction for ${\cal B}(K^0_L\toμ^+μ^-)$. We then move on to feasibility studies within an LHCb-like setup, using both time-integrated and time-dependent information, employing $K^0$ and $\overline K{}^0$ tagging methods. We find that, within an optimistic scenario, the short-distance amplitude, proportional to the CKM parameter combination $|A^2λ^5\barη|$, could be constrained by LHCb at the level of about $35\%$ of its Standard Model value, and the discrete ambiguity in ${\cal B}(K^0_L\toμ^+μ^-)_{\rm SM}$ could be resolved at more than $3σ$ by the end of the high luminosity LHC