abstract

The quantum interference effects have been studied across many collision systems with a wide spectrum of energies and particle species. They were the subject of studies in many experiments using different accelerators. Studying the quantum correlations may provide essential information to understand the mechanism of hadronization, describing in particular the space-time structure of the hadronization source. As the measured correlation parameters depend on various observables, such as charged particle multiplicity, transverse momentum, or hadron mass, it is essential to model the observed trends properly. In particular, it was observed that the correlation radii become smaller with an increasing mass of the studied hadron species, which was a conclusion driven mainly by the LEP measurements performed for a number of different types of hadrons. One of the approaches aiming at interpretation of the observed dependence of the correlation radius on the hadron mass is the quantum-mechanical model employing the Björken–Gottfried condition, suggesting the universality of the source radius, which is independent of the hadron mass.

abstract

I discuss recent results that confirm that one can associate entropy with partonic content of the proton. Furthermore, I show that complexity of the proton is characterized by the parton momentum density function.

abstract

This contribution provides an overview of the Large Hadron Collider operation during Run 3, highlighting key achievements and challenges encountered. A detailed account of major LHC events and results in 2023 and 2024 is presented, including notable milestones in machine operation, luminosity evolution, and beam performance for protons and ions. Additionally, prospects for LHC operations in 2025 and 2026 are discussed, outlining planned improvements and expected operational scenarios. Finally, the status of the High-Luminosity LHC preparation is reviewed, focusing on key upgrades, infrastructure developments, and current schedule.

abstract

This report summarises measurements of the Higgs boson properties performed with the CMS experiment at the CERN LHC. The measurements presented here base on data from \(pp\) collisions at the center-of-mass energy of 7, 8, and 13 TeV collected up to the year 2018 and corresponding to integrated luminosity of 5, 20, and 138 fb\(^{-1}\), respectively. These results represent the most up-to-date knowledge on the Higgs boson properties. All presented measurements agree with predictions of the Standard Model of particle physics within their uncertainties.

abstract

Electroweak measurements are a key part of the CMS Collaboration’s physics program, enabling precise measurements of known observables. These measurements are crucial for placing stringent limits on Standard Model parameters providing insights into New Physics. Presented here are some of the latest results from the CMS Collaboration, including the first results using Run 3 data collected at \(\sqrt {s}=13.6\) TeV in 2024.

abstract

ATLAS (A Toroidal LHC Apparatus) detector will undergo modernization between 2026 and 2030 to prepare for operations in the high-luminosity regime of the High-Luminosity Large Hadron Collider. Patch Panel 2 (PP2) is an active component of the strip tracker’s power supply (PS) chain, which will be located inside the ATLAS detector. For safety and control reasons, an independent readout system is needed to connect to PP2. This paper presents the PP2 control and monitoring system as implemented during the prototype and pre-production phases and outlines the quality control plans for the pre-production PP2 series currently under development in Kraków.

abstract

With the LHC full Run 2 \(pp\) collision dataset collected at 13 TeV, very precise measurements of Higgs boson properties and its interactions can be performed, shedding light on the electroweak symmetry-breaking mechanism. This contribution presents measurements performed using the Run 2 dataset, as well as first results using the Run 3 \(pp\) collision dataset collected since 2022 at 13.6 TeV. Measurements of the Higgs boson properties by the ATLAS experiment in various decay channels are shown, including its production cross sections, simplified template cross sections, mass, width, differential and fiducial cross sections, as well as their combination and interpretations. Specific scenarios of physics beyond the Standard Model are tested, as well as a generic extension in the framework of the Standard Model Effective Field Theory. The paper also presents the latest \(HH\) searches, which are sensitive to the Higgs boson self-coupling. Results are shown in terms of sensitivity to the SM \(HH\) production and limits on the Higgs boson self-coupling.

abstract

Recent measurements from the heavy-ion physics programme from the ATLAS experiment at the LHC are reviewed. They include azimuthal flow at high transverse momenta (\(p_{\mathrm {T}}\)), \(p_{\mathrm {T}}\) fluctuations in lead–lead (Pb+Pb) and xenon–xenon (Xe+Xe) collisions, jet-radius dependence of di-jet asymmetry, and an observation of top-quark pair production in proton–lead (\(p\)+Pb) and Pb+Pb systems. Results of a search for a diffusion wake in \(\gamma \)–jet events are also discussed. Moreover, results from ultra-peripheral collisions for photonuclear di-jet production and a search for magnetic monopoles are presented.

abstract

The strong electromagnetic field induced by a nucleus moving with relativistic velocity in ultraperipheral collisions is a source of the quasireal photons, which can be absorbed by the partner nucleus and excite it. This leads to the evaporation of particles such as neutrons, protons, and alpha particles. In our recent work, we applied the Equivalent Photon Approximation to calculate the cross sections for evaporation of given multiplicities of particles. We tested different statistical nuclear models, such as GEMINI++ and HIPSE, to define the probability functions. We also suggested a new, phenomenological approach for the estimation of excitation energy called the Two Component Model. The results were compared with recent ALICE data obtained with the neutron and proton Zero Degree Calorimeters.

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The Compact Muon Solenoid detector (CMS) was designed to analyze data mainly from proton–proton collision, but its robust design allows also for the analysis of data from heavy-ion collisions. This contribution describes a few examples of recent results of heavy-ion data analyses from CMS.

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The LHCb experiment at CERN’s Large Hadron Collider is dedicated to studying heavy-flavour physics, particularly the decays and properties of beauty and charm hadrons, to explore CP violation and phenomena beyond the Standard Model. This contribution presents a selection of recent measurements in rare decays and CP violation.

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Small violations of CPT symmetry are permissible in several extensions of the Standard Model. Recently, we published new constraints on the CPT violation parameter \(z\) by reinterpreting the LHCb measurement of the time-dependent asymmetry in the Cabbibo-favoured \(D^0 \rightarrow K^{-}\pi ^{+}\) and \(\bar {D}^{0} \rightarrow K^{+}\pi ^{-}\) decays. The resulting limits are two orders of magnitude stricter than the previous leading result reported by the FOCUS Collaboration. In this contribution, we discuss the recent result, which is the tightest constraint on the CPTV in the charm sector to date. We also explore prospects for placing bounds on CPT violation in the Standard Model Extension framework.

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In this paper, we present the search for three highly-suppressed Standard Model processes at the CMS experiment: \(B^{0} \to \mu ^+ \mu ^-\), \(B_{s}^{0} \to \mu ^+ \mu ^-\), and \(B_{s}^{0} \to \mu ^+ \mu ^- \gamma \). The latest and most precise results to date are presented for the first two decays, while the feasibility and experimental strategy for the third, yet unobserved at CMS, are discussed. The search for New Physics is the primary motivation for studying these flavour-changing neutral current decays.

abstract

The CMS experiment has delivered numerous significant measurements using data from LHC Run 2 and the ongoing Run 3. This report explains key components of the CMS detector relevant to heavy-flavour physics. The short introduction to CP violation in \(B_s\rightarrow J/\psi \phi (1020)\) is given, followed by the recent CMS results, confirming the CP violation in this channel. The search for CP violation in \(D_s\rightarrow K_\mathrm {S}^0 K_\mathrm {S}^0\) channel is presented. In addition, the most important information on selected recent CMS heavy-flavour physics results is highlighted. It includes: measurement of \(B_s\rightarrow J/\psi K_\mathrm {S}\) effective lifetime, test of lepton flavour universality with \(R_{J/\psi }\), and search for rare decays in \(D^0\rightarrow \mu ^+\mu ^-\). Finally, the CMS measurements of \(B/B_s\rightarrow \mu ^+\mu ^-\) are reminded.

abstract

Quantum electrodynamics mechanisms can be used to analyse the proton structure, with particular attention paid to its radius. The cross section for the \(\gamma \gamma \to \ell ^+\ell ^-\) process is placed in the context of proton–proton collisions, allowing for the study of effects related to the distribution of the electromagnetic field around the proton. This research compares the theoretical results with the data from the ATLAS and CMS experiments at the LHC. It allows for the verification of the approach used and the determination of possible model constraints.

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We propose the use of a decoupling renormalization scheme in the calculation of NLO corrections to SM-like Higgs boson decays in the beyond the Standard Model models. The advantage of this particular scheme is its decoupling property in the presence of a heavy BSM physics and the possibility to directly include known higher-order Standard Model corrections. We illustrate the use of this scheme by analysing the \(h \to \mu ^+ \mu ^-\) decay in a simple Standard Model extension by an \(S_1\) leptoquark.

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Recent theoretical results renewed the interest in charged-particle multiplicity distributions. The Shannon entropy of such distributions is conjectured to be related to the entanglement or von Neumann entropy of the partonic quantum system. In this paper, we show that the measured charged-particle multiplicities can be derived from the principle of maximum entropy (POME or MAXENT) without any a priori physical assumption. The approach provides a natural explanation for the well-known negative binomial shape of the measured distributions.

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The extensive top-quark samples collected by the ATLAS experiment at the LHC have enabled precise measurements of the top-quark production cross section, reaching unprecedented accuracy and extending into previously unexplored kinematic regimes. These datasets have also provided new insights into top-quark properties, facilitated the observation of rare production processes predicted by the Standard Model, and led to significant advancements in searches within the top-quark sector. This contribution presents key highlights from the ATLAS top-quark physics program, showcasing the latest measurements and emphasizing the sector’s broad scientific potential.

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Reconstruction of the invariant mass of the system with two tau leptons faces a challenge of lack of neutrinos in the observed final state of taus’ decays. In this work, we introduce a novel algorithm, which is comparable to other mass reconstruction algorithms in the field of mass resolution and much better considering time performance. We test its performance on Monte Carlo simulations with PYTHIA and Delphes and show that algorithm achieves an average execution time of approximately 3 ms per event, which is around two orders of magnitude faster than previous techniques, while delivering a mass resolution characterized by a standard deviation of \(22\) GeV for \(Z^0\) bosons and \(34.5\) GeV for Higgs bosons. A Python implementation of the method is provided in an open-source repository, facilitating broader adoption in high-energy physics analyses.

abstract

Neutrinos are mysterious elementary particles due to their tiny masses, electrical neutrality, and interaction only through gravitational and weak force, which makes their detection challenging. Their astrophysical origins and the production mechanism remain unclear. This contribution will presents the prospect of the acoustic simulation to detect ultra-high-energy (UHE) neutrinos with KM3NeT. KM3NeT, the Cubic Kilometer Neutrino Telescope located in the Mediterranean Sea, is equipped with state-of-the-art hydrophones and digital optical modules. To investigate the high-energy astrophysical origins of neutrinos, a study of tidally disrupted events as potential candidates is proposed.

abstract

The High Luminosity Large Hadron Collider (HL-LHC) will provide additional challenges in the already demanding field of charged-particle-track reconstruction. The Inner Detector of the ATLAS experiment will be replaced by an all-silicon Inner Tracker (ITk) that will consist of pixel and strip subdetectors providing greater coverage in pseudorapidity spanning up to \(|\eta |=4\). The physics of heavy ions (HI) requires a different tracking setup as compared to \(pp\) collisions. This is dictated by the difference in experimental conditions, where instead of a huge number of simultaneous \(pp\) interactions per bunch crossing (up to \(\langle \mu \rangle =200\)), the HI collision events expect only one collision per bunch crossing. Despite this, a central lead-ion collision produces a huge number of charged particles to reconstruct, comparable to \(pp\) collisions at \(\langle \mu \rangle =200\). The presence of a single collision vertex enables certain optimizations but also introduces unique challenges. The ATLAS experiment has chosen A Common Tracking Software (ACTS) for the HL-LHC to perform track reconstruction, as it is expected to meet the new challenges ahead. This document highlights the progress in setting up the ACTS-based track reconstruction for HI with the ITk, shows a comparison of expected tracking performance in \(pp\) and HI events, and presents the predicted performance of ACTS compared to the existing tracking algorithms used by ATLAS.

abstract

The Top–Down reconstruction chain is a Monte Carlo simulation scheme that focuses on reconstructing observed extensive air showers while accounting for the muon discrepancy between the observed and simulated events. With the help of this algorithm, we try to reconstruct a particularly unique air shower observed by the Pierre Auger Observatory. The uniqueness of this observation lies in the very large depth of its maximum. We have modified the Top–Down chain to accommodate this unique event and present the Top–Down simulated events, which are the best match to the air shower studied.

abstract

The AFP global alignment method using photon-fusion-induced lepton pair production is discussed. The alignment corrections are derived from a comparison of the expected proton positions to the measured ones. Results obtained with di-muon events are verified with di-electron events.

abstract

The Precision Proton Spectrometer is a subdetector of the CMS experiment at the LHC used for detecting forward protons. It comprises tracking and timing detectors located around 220 meters from the CMS detector, along the LHC beam pipe, on both sides. Due to their challenging operating environment, they require frequent calibration. Procedures for performing these calibrations have already been developed in LHC Run 2 (2015–2018), but in Run 3 (2022–2026), the timing detector calibration algorithm has been shown not to perform ideally for most of the data-taking runs due to data anomalies and irregularities. Moreover, calibrating so many runs every year is a tedious task. As a result, an in-house parallel processing automation framework has been developed to perform the calibration and validate its results. In the paper, an improved timing calibration algorithm was shown, as well as anomalies and irregularities that were observed and corrected using it.

abstract

Lepton Flavor Violation (LFV) in the neutral lepton sector (neutrino oscillation mechanism) compels us to check for LFV in other physics processes to hunt for any New Physics (NP) signatures. LFV \(B\)-meson decays \(B\rightarrow K \tau \ell \) (\(\ell = e,\mu \)) are one such example, which in some NP scenarios are within the reach of current experimental sensitivity. We are searching for them in Belle, which provides a clean environment to study such processes. Using the boosted decision tree approach, we have significantly suppressed the background. Validation of the analysis approach is performed on two different control modes, and we have found reasonable agreement between the Belle data and Monte Carlo (MC).

abstract

Some of the outstanding issues of the Standard Model (SM) can be solved with an extension of its scalar sector. We discuss SM extensions to tackle matter–antimatter asymmetry, the shape of the Higgs potential, and dark matter. The amount of CP-violation in the SM is not sufficient for baryogenesis and, therefore, new sources of CP-violation are needed. Searches for CP-violation are one of the top priorities of the future LHC runs. Also, the still unknown shape of the Higgs potential can be probed in di-Higgs final states at the LHC. Finally, extensions of the SM can provide dark matter candidates which can be probed at the LHC in events with a large amount of missing energy, together with one or more SM particles.

abstract

Next-to-leading order (NLO) QCD predictions coupled with parton showers, known as NLO matching, have been widely used for the precision era at the LHC. While two methods — Mc@Nlo and Powheg — have been widely adopted for this purpose, a third method, KrkNLO, has recently been described and implemented within Herwig 7 for colour-singlet processes. We present phenomenological results of this method for the charged-current Drell–Yan process and compare with the Mc@Nlo method.

abstract

We discuss the production of \(D\) mesons and \(J/\psi \) quarkonia in proton–nucleus collisions in the fixed-target LHCb experiment. We consider gluon–gluon fusion within \(k_{\mathrm {t}}\)-factorization, processes initiated by intrinsic charm in the nucleon and perturbative recombination mechanism. All the mechanisms seem to be necessary to describe the LHCb experimental data. We get an upper limit for the probability of the large-\(x\) \(c \bar c\) Fock component in the nucleon, which is slightly less than 1%. The recombination mechanism allows for the description of \(D^0\) and \(\bar D^0\) asymmetry observed by the LHCb Collaboration. We also discuss the production of \(J/\psi \) quarkonia, including colour singlet mechanisms. We include \(g^* g^* \to J/\psi g\) and \(g^* g^* \to \chi _c(1^+,2^+)(\to J/\psi \gamma )\) within \(k_{\mathrm {t}}\)-factorization approach. Different unintegrated gluon distributions from the literature are used. A reasonable agreement is achieved with some gluon distributions from the literature.

abstract

A summary of CMS searches for new neutral resonances with the main focus on scalars and pseudoscalars, based on data collected during Run 2 of the LHC is presented. Special emphasis is given to the most recent results.

abstract

Processes with scattered protons present in the final state, hereafter called forward physics, are briefly described. ATLAS sub-detectors, ALFA and AFP, dedicated to measure scattered protons, are shown. A few analyses using data collected by these detectors are presented. Namely, elastic scattering at \(\sqrt {s} = 7\), 8, and 13 TeV, exclusive di-pion and di-lepton production, and a search for the axion-like particles.

abstract

This document presents an overview of recent ATLAS searches in the Higgs sector using the full Run 2 dataset of proton–proton collisions at \(\sqrt {s} = 13\) TeV, corresponding to an integrated luminosity of 140 fb\(^{-1}\). The analyses include searches for additional scalars, charged Higgs bosons, and exotic decays.

abstract

The ATLAS experiment at the Large Hadron Collider continues to deliver high-precision measurements that probe the electroweak sector of the Standard Model. This summary highlights recent results using proton–proton collision data, including precision determinations of the \(W\)-boson mass and width, measurements of exclusive hadronic \(W\) decays, and studies of \(W\)- and \(Z\)-boson production. New insights into the electroweak gauge structure through studies of diboson polarization, radiation amplitude zero effects, and rare quartic gauge couplings are also reviewed. These results offer stringent tests of the Standard Model and increase sensitivity to potential New Physics.

abstract

Heavy flavour production cross sections and lifetimes in hadron colliders inform and challenge perturbative and non-perturbative quantum chromodynamics (QCD) determinations, while providing sensitivity to physics beyond the Standard Model. Using up to 140 fb\(^{-1}\) of \(pp\) collisions at \(\sqrt {s}=13\) TeV from Run 2 of the LHC, recent results from the ATLAS experiment are presented: differential charmonium production cross sections extending up to transverse momenta (\(p_{\mathrm {T}}\)) of 360 GeV (\(J/\psi \)) and 140 GeV (\(\psi (2S)\)), differential open-charm \(D^\pm \) and \(D^\pm _s\) meson production cross sections extending up to \(p_{\mathrm {T}} = 100\) GeV, and the open-beauty \(B^0\) meson effective lifetime of \(\tau _{B^0} = 1.5053 \pm 0.0012 \mathrm {(stat.)} \pm 0.0035 \mathrm {(syst.)}\) ps, to date the most precise single measurement of this quantity.

abstract

The ALICE experiment has significantly upgraded its detectors, enabling new measurements in ultra peripheral collisions of lead nuclei with an integrated luminosity of \(\mathcal {L} = 7\)/nb and 6/nb during Run 3 and Run 4, respectively. Investigation of light-by-light scattering in the low diphoton invariant mass is studied in this paper. The predictions presented here take into account the acceptance of the current EMCal and PHOS electromagnetic calorimeters, TPC and ITS tracking devices in the central barrel, as well as the future Forward Calorimeter, FoCal. Results from the SuperChic and UPCgen Monte Carlo generators are compared across all possible reconstruction topologies.

abstract

We study the \(th\) production at the LHC in the presence of a CP violating top Yukawa coupling. The helicity amplitudes for the \(ub\to dth\)(\(d\bar {b}\to u\bar {t}h\)) processes provide information on the kinematical distributions. Observables such as the azimuthal asymmetry between the forward jet and the top (antitop) quark, and the top (antitop) quark polarization asymmetry can be used to probe CP violation.