Pietro Govoni

This Report summarizes the results of the activities in 2012 and the first half of 2013 of the LHC Higgs Cross Section Working Group. The main goal of the working group was to present the state of the art of Higgs Physics at the LHC, integrating all new results that have appeared in the last few years. This report follows the first working group report Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002) and the second working group report Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002). After the discovery of a Higgs boson at the LHC in mid-2012 this report focuses on refined prediction of Standard Model (SM) Higgs phenomenology around the experimentally observed value of 125-126 GeV, refined predictions for heavy SM-like Higgs bosons as well as predictions in the Minimal Supersymmetric Standard Model and first steps to go beyond these models. The other main focus is on the extraction of the characteristics and properties of the newly discovered particle such as couplings to SM particles, spin and CP-quantum numbers etc.

The successful operation of the Large Hadron Collider (LHC) and the excellent performance of the ATLAS, CMS, LHCb and ALICE detectors in Run-1 and Run-2 with $pp$ collisions at center-of-mass energies of 7, 8 and 13 TeV as well as the giant leap in precision calculations and modeling of fundamental interactions at hadron colliders have allowed an extraordinary breadth of physics studies including precision measurements of a variety physics processes. The LHC results have so far confirmed the validity of the Standard Model of particle physics up to unprecedented energy scales and with great precision in the sectors of strong and electroweak interactions as well as flavour physics, for instance in top quark physics. The upgrade of the LHC to a High Luminosity phase (HL-LHC) at 14 TeV center-of-mass energy with 3 ab$^{-1}$ of integrated luminosity will probe the Standard Model with even greater precision and will extend the sensitivity to possible anomalies in the Standard Model, thanks to a ten-fold larger data set, upgraded detectors and expected improvements in the theoretical understanding. This document summarises the physics reach of the HL-LHC in the realm of strong and electroweak interactions and top quark physics, and provides a glimpse of the potential of a possible further upgrade of the LHC to a 27 TeV $pp$ collider, the High-Energy LHC (HE-LHC), assumed to accumulate an integrated luminosity of 15 ab$^{-1}$.

Vector-boson scattering processes are of great importance for the current run-II and future runs of the Large Hadron Collider. The presence of triple and quartic gauge couplings in the process gives access to the gauge sector of the Standard Model (SM) and possible new-physics contributions there. To test any new-physics hypothesis, sound knowledge of the SM contributions is necessary, with a precision which at least matches the experimental uncertainties of existing and forthcoming measurements. In this article we present a detailed study of the vector-boson scattering process with two positively-charged leptons and missing transverse momentum in the final state. In particular, we first carry out a systematic comparison of the various approximations that are usually performed for this kind of process against the complete calculation, at LO and NLO QCD accuracy. Such a study is performed both in the usual fiducial region used by experimental collaborations and in a more inclusive phase space, where the differences among the various approximations lead to more sizeable effects. Afterwards, we turn to predictions matched to parton showers, at LO and NLO: we show that on the one hand, the inclusion of NLO QCD corrections leads to more stable predictions, but on the other hand the details of the matching and of the parton-shower programs cause differences which are considerably larger than those observed at fixed order, even in the experimental fiducial region. We conclude with recommendations for experimental studies of vector-boson scattering processes.

Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and prospects of LHC running with 10 to 300 fb−1 of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10 fb−1 of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions.

Insight into the electroweak (EW) and Higgs sectors can be achieved through measurements of vector boson scattering (VBS) processes. The scattering of EW bosons are rare processes that are precisely predicted in the Standard Model (SM) and are closely related to the Higgs mechanism. Modifications to VBS processes are also predicted in models of physics beyond the SM (BSM), for example through changes to the Higgs boson couplings to gauge bosons and the resonant production of new particles. In this review, experimental results and theoretical developments of VBS at the Large Hadron Collider, its high luminosity upgrade, and future colliders are presented.

We report on the response of microchannel plates (MCPs) to single relativistic particles and to electromagnetic showers. Particle detection by means of secondary emission of electrons at the MCP surface has long been proposed and is used extensively in ion time-of-flight mass spectrometers. What has not been investigated in depth is their use to detect the ionizing component of showers. The time resolution of MCPs exceeds anything that has been previously used in calorimeters and, if exploited effectively, could aid in the event reconstruction at high luminosity colliders. Several prototypes of photodetectors with the amplification stage based on MCPs were exposed to cosmic rays and to 491 MeV electrons at the INFN-LNF Beam-Test Facility. The time resolution and the efficiency of the MCPs are measured as a function of the particle multiplicity, and the results used to model the response to high-energy showers.

This document summarises the talks and discussions happened during the VBSCan Split17 workshop, the first general meeting of the VBSCan COST Action network. This collaboration is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3~\mathrm{ab}^{-1}$ of data taken at a centre-of-mass energy of $14~\mathrm{TeV}$, and of a possible future upgrade, the High Energy (HE) LHC, defined as $15~\mathrm{ab}^{-1}$ of data at a centre-of-mass energy of $27~\mathrm{TeV}$. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by $20-50\%$ on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics.

The successful operation of the Large Hadron Collider (LHC) and the excellent performance of the ATLAS, CMS, LHCb and ALICE detectors in Run-1 and Run-2 with $pp$ collisions at center-of-mass energies of 7, 8 and 13 TeV as well as the giant leap in precision calculations and modeling of fundamental interactions at hadron colliders have allowed an extraordinary breadth of physics studies including precision measurements of a variety physics processes. The LHC results have so far confirmed the validity of the Standard Model of particle physics up to unprecedented energy scales and with great precision in the sectors of strong and electroweak interactions as well as flavour physics, for instance in top quark physics. The upgrade of the LHC to a High Luminosity phase (HL-LHC) at 14 TeV center-of-mass energy with 3 ab$^{-1}$ of integrated luminosity will probe the Standard Model with even greater precision and will extend the sensitivity to possible anomalies in the Standard Model, thanks to a ten-fold larger data set, upgraded detectors and expected improvements in the theoretical understanding. This document summarises the physics reach of the HL-LHC in the realm of strong and electroweak interactions and top quark physics, and provides a glimpse of the potential of a possible further upgrade of the LHC to a 27 TeV $pp$ collider, the High-Energy LHC (HE-LHC), assumed to accumulate an integrated luminosity of 15 ab$^{-1}$.

We present a parton-level study of electro-weak production of vector-boson pairs at the Large Hadron Collider, establishing the sensitivity to a set of dimension-six operators in the Standard Model Effective Field Theory (SMEFT). Different final states are statistically combined, and we discuss how the orthogonality and interdependence of different analyses must be considered to obtain the most stringent constraints. The main novelties of our study are the inclusion of SMEFT effects in non-resonant diagrams and in irreducible QCD backgrounds, and an exhaustive template analysis of optimal observables for each operator and process considered. We also assess for the first time the sensitivity of vector-boson-scattering searches in semileptonic final states.

Performance tests of some aspects of the CMS ECAL were carried out on modules of the "barrel" sub-system in 2002 and 2003. A brief test with high energy electron beams was made in late 2003 to validate prototypes of the new Very Front End electronics. The final versions of the monitoring and cooling systems, and of the high and low voltage regulation were used in these tests. The results are consistent with the performance targets including those for noise and overall energy resolution, required to fulfil the physics programme of CMS at the LHC.

We present a feasibility study for the use of a generative, probabilistic model, a Variational Autoencoder (VAE), to detect deviations from Standard Model (SM) physics in an electroweak process at the Large Hadron Collider (LHC). The new physics responsible for the anomalies is described through an Effective Field Theory (EFT) approach: the SM Lagrangian is Taylor-expanded and the higher order terms cause deviations in the kinematic distributions of the observables, and are thus identified by the model as anomalous contributions with respect to SM. Since the training of the model involves almost only SM events, the proposed strategy is largely independent from any assumption on the nature of the new physics signature. To test the proposed strategy we use parton level generations of Vector Boson Scattering (VBS) events at the LHC, assuming an integrated luminosity of 350 fb $$^{-1}$$ .

A new methodology to improve the sensitivity to new physics contributions to the Standard Model processes at LHC is presented. A Variational AutoEncoder trained on Standard Model processes is used to identify Effective Field Theory contributions as anomalies. While the output of the model is supposed to be very similar to the inputs for Standard Model events, it is expected to deviate significantly for events generated through new physics processes. The reconstruction loss can then be used to select a signal enriched region which is by construction independent of the nature of the chosen new physics process. In order to improve further the discrimination power, an adversarial layer is introduced with a cross entropy term added to the loss function, optimizing at the same time the reconstruction of the input variables of the Standard Model and classification of new physics processes. This procedure ensures that the model is optimized for discrimination, with a small price in terms of model dependency to physics process. In this work I will discuss in detail the above-mentioned method using generator level Vector Boson Scattering events produced at LHC assuming an integrated luminosity of 350/fb.

Abstract In 1956 Reines & Cowan discovered the neutrino using a liquid scintillator detector. The neutrinos interacted with the scintillator, producing light that propagated across transparent volumes to surrounding photo-sensors. This approach has remained one of the most widespread and successful neutrino detection technologies used since. This article introduces a concept that breaks with the conventional paradigm of transparency by confining and collecting light near its creation point with an opaque scintillator and a dense array of optical fibres. This technique, called LiquidO, can provide high-resolution imaging to enable efficient identification of individual particles event-by-event. A natural affinity for adding dopants at high concentrations is provided by the use of an opaque medium. With these and other capabilities, the potential of our detector concept to unlock opportunities in neutrino physics is presented here, alongside the results of the first experimental validation.

A precise calibration and monitoring system has been developed for the HARP experiment scintillator-based time of flight system. An Nd-YAG laser with passive Q-switch and active/passive mode-locking and a custom-made laser light injection system based on a bundle of IR monomode optical fibers were used. The laser pulse timing was provided by a novel ultrafast InGaAs MSM photodiode, with 30 ps risetime. Experience over a several month data taking period in 2001 and 2002 shows that drifts in timing down to about 70 ps can be traced.

Abstract We report on a consistent comparison between techniques of quantum and classical machine learning applied to the classification of signal and background events for the Vector Boson Scattering processes, studied at the Large Hadron Collider installed at the CERN laboratory. Quantum machine learning algorithms based on variational quantum circuits are run on freely available quantum computing hardware, showing very good performances as compared to deep neural networks run on classical computing facilities. In particular, we show that such kind of quantum neural networks is able to correctly classify the targeted signal with an Area Under the characteristic Curve (AUC) that is very close to the one obtained with the corresponding classical neural network, but employing a much lower number of resources, as well as less variable data in the training set. Albeit giving a proof-of-principle demonstration with limited quantum computing resources, this work represents one of the first steps towards the use of near term and noisy quantum hardware for practical event classification in High Energy Physics experiments.

Hundreds of concurrent collisions per bunch crossing are expected at future hadron colliders. Precision timing calorimetry has been advocated as a way to mitigate the pileup effects and, thanks to their excellent time resolution, microchannel plates (MCPs) are good candidate detectors for this goal. We report on the response of MCPs, used as secondary emission detectors, to single relativistic particles and to electromagnetic showers. Several prototypes, with different geometries and characteristics, were exposed to particle beams at the INFN-LNF Beam Test Facility and at CERN. Their time resolution and efficiency are measured for single particles and as a function of the multiplicity of particles. Efficiencies between 50% and 90% to single relativistic particles are reached, and up to 100% in presence of a large number of particles. Time resolutions between 20 ps and 30 ps are obtained.

The CMS Electromagnetic crystal Calorimeter (ECAL) must be precisely inter-calibrated if its full potential performance is to be realized.In this note, a detailed Monte Carlo study of in-situ intercalibration of the ECAL crystals using isolated electrons is described.The achievable precision depends on the quality and number of available electrons per crystal.This in turn depends upon the position of the crystals and the corresponding thickness of material in front of the ECAL.

At the high luminosity LHC (HL-LHC) about 200 concurrent interactions are expected, with a spread between the interaction vertices of few centimeters in the beam direction and 200 ps in the collision time. A time of flight resolution of the order of 30 ps would be able to reduce neutral particles pile-up contamination at the calorimeter level of about one order of magnitude, restoring pile-up conditions similar to what is routinely sustained in the current run of the LHC . Micro-channel plates have been used in PMT configuration as fast charged particles detector (resolution of better than 20 ps have been achieved with commercial devices), however they are not particularly radiation tolerant, mostly due to the ion feedback on the photocathode. The possibility of using micro-channel plates without a photocathode (i-MCP) has been studied in several test beams. Different MCP geometries are compared with the goal to identify the optimal configuration. Efficiency of more then 70% with a time resolution of better than 40 ps are achieved for single charged particles, leading to an efficiency close to 100% for EM shower after few radiation lengths. This open the possibility to use i-MCPs as a timing layer in a sampling calorimeter or to use it in a pre-shower device independent from the calorimeter technology.

WW scattering is an important process to study electroweak symmetry breaking in the Standard Model at the LHC, in which the Higgs mechanism or other new physics processes must intervene to preserve the unitarity of the process below 1 TeV. This channel is expected to be one of the most sensitive to determine whether the Higgs boson exists. In this paper, the final state with two same sign Ws is studied, with a simulated sample corresponding to the integrated luminosity of 60 fb−1 in pp collision at $\sqrt{s}=10$ TeV. Two observables, the invariant mass of μμ from W decays and the azimuthal angle difference between the two μs, are utilized to distinguish the Higgs boson existence scenario from the Higgs boson absence scenario. A good signal significance for the two cases can be achieved. If we define the separation power of the analysis as the distance, in the log-likelihood plane, of pseudo-experiments outcomes in the two cases, with the total statistics expected from the ATLAS and CMS experiments at the nominal center-of-mass energy of 14 TeV, the separation power will be at the level of 4 σ.

For the physics program of the CMS experiment at the LHC to be carried out successfully, excellent electromagnetic calorimetry is required. Given the thermal properties of CMS ECAL, keeping the constant term of the energy resolution below 0.5% needs its temperature to be stabilized at 18/spl deg/C within 0.05/spl deg/C. A prototype module of ECAL with the final cooling system has been tested at CERN to check its integration with the read-out electronics and verify that it complies with the severe thermal requirements. The thermal performance of the cooling system is reported here.

A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a Geant4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype׳s energy resolution.

The electromagnetic calorimeter of the CMS experiment at the new CERN proton–proton Collider (LHC) is at an advanced stage of construction. A necessary condition for its optimal performance is a precise channel-to-channel calibration. The use of cosmic rays allows the pre-calibration of all the channels at the level of 2% before the final installation in CMS and provides an extensive functionality test, essential for the commissioning of the detector. On the other hand, a beam of electrons permits extremely precise (better than 0.5%) pre-calibration coefficients to be obtained on a fraction of the calorimeter, which can also be used as a reference for the in situ calibration procedures that will rely on physics data.

TeV scale new physics, e.g., large extra dimensions or models with anomalous triple vector boson couplings, can lead to excesses in various kinematic regions on the semileptonic productions of $pp\ensuremath{\rightarrow}WW\ensuremath{\rightarrow}l\ensuremath{\nu}jj$ at the CERN LHC, which, although suffer from large QCD background compared with the pure leptonic channel $pp\ensuremath{\rightarrow}WW\ensuremath{\rightarrow}l\ensuremath{\nu}l\ensuremath{\nu}$, can benefit from larger production rates and the reconstructable four-body mass ${M}_{l\ensuremath{\nu}jj}$. We study the search sensitivity through the $l\ensuremath{\nu}jj$ channel at the 7 TeV LHC on relevant new physics via probing the hard tails on the reconstructed ${M}_{l\ensuremath{\nu}jj}$ and the transverse momentum of leptonically decayed $W$ boson (${P}_{TW}$), taking into account main backgrounds and including the parton shower and detector simulation effects. Our results show that with integrated luminosity of $5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, the LHC can already discover or exclude a large parameter region of the new physics, e.g., a 95% C.L. can be set on the large extra dimensions with a cutoff scale up to 1.5 TeV, and the $WWZ$ anomalous coupling down to, e.g., $|{\ensuremath{\lambda}}_{Z}|\ensuremath{\sim}0.1$. Results are also given for the 8 TeV LHC.

We present the first parton-level study of anomalous effects in triboson production in both fully and semi-leptonic channels in proton-proton collisions at 13 TeV at the Large Hadron Collider (LHC). The sensitivity to anomalies induced by a minimal set of bosonic dimension-6 operators from the Warsaw basis is evaluated with specific analyses for each final state. A likelihood-based strategy is employed to assess the most sensitive kinematic observables per channel, where the contribution of Effective Field Theory operators is parameterized at either the linear or quadratic level. The impact of the mutual interference terms of pairs of operators on the sensitivity is also examined. This benchmark study explores the complementarity and overlap in sensitivity between different triboson measurements and paves the way for future analyses at the LHC experiments. The statistical combination of the considered final states allows setting stringent bounds on five bosonic Wilson coefficients.

A bstract We present the first parton-level study of anomalous effects in triboson production in both fully and semi-leptonic channels in proton-proton collisions at 13 TeV at the Large Hadron Collider (LHC). The sensitivity to anomalies induced by a minimal set of bosonic dimension-6 operators from the Warsaw basis is evaluated with specific analyses for each final state. A likelihood-based strategy is employed to assess the most sensitive kinematic observables per channel, where the contribution of Effective Field Theory operators is parameterized at either the linear or quadratic level. The impact of the mutual interference terms of pairs of operators on the sensitivity is also examined. This benchmark study explores the complementarity and overlap in sensitivity between different triboson measurements and paves the way for future analyses at the LHC experiments. The statistical combination of the considered final states allows setting stringent bounds on five bosonic Wilson coefficients.

AI models are likely to become useful tools to support clinical decision-making especially in high mortality diseases such as lung cancer. However, the black-box nature of these models remains nowadays the main challenge to be addressed to employ AI in the clinic. This work describes the preliminary stages and results obtained by implementing a novel explainable approach in radiomics pipeline for local recurrence prediction of lung cancer and its technical validation relying on the high energy physics domain.

I-MCP is an R&D project aimed at the exploitation of secondary emission of electrons from the surface of micro-channel plates (MCP) for single ionizing particles and fast timing of showers in high rate environments. Results from tests with electrons with energies up to 50 GeV of MCP devices with different characteristics are presented. In particular detection efficiency and time resolution are measured for a range of MCP prototypes: different MCP channel diameter and layers configuration are studied. Devices operated in I-MCP configuration, where the particle detection proceed through direct ionization of the MCP layers, are studied in comparison with the more usual PMT-MCP configuration. The results show efficiencies up to 70% for single charge particle detection for I-MCP devices with a time resolution of about 40 ps. The efficiency raise to 100% in response to high energy electromagnetic showers.

This document summarises the talks and discussions happened during the VBSCan Mid-Term Scientific Meeting workshop. The VBSCan COST action is dedicated to the coordinated study of vector boson scattering (VBS) from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

A calibration and monitoring system for the Harp experiment scintillator-based time of flight system has been developed, by using an Nd-YAG laser with passive Q-switch and active/passive mode-locking and a custom made laser light injection system based on it bundle of IR monomode optical fibers. For the laser pulse timing a novel ultrafast InGaAs MSM photodiode, with 30 ps risetime, has been used. Experience over a several months data taking period in 2001 and 2002 shows that drifts in timing down to about 70 ps can be traced.

The High-Luminosity phase of the Large Hadron Collider at CERN (HL-LHC) poses stringent requirements on calorimeter performance in terms of resolution, pileup resilience and radiation hardness. A tungsten-CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> sampling calorimeter is a possible option for the upgrade of current detectors. A prototype, read out with different types of wavelength-shifting fibers, has been built and exposed to high energy electrons, representative for the particle energy spectrum at HL-LHC, at the CERN SPS H4 beam line. This paper shows the performance of the prototype, mainly focussing on energy resolution and uniformity. A detailed simulation has been also developed in order to compare with data and to extrapolate to different configurations to be tested in future beam tests. Additional studies on the calorimeter and the R&D projects ongoing on the various components of the experimental setup will be also discussed.

The production of Z bosons via Vector Boson Fusion at the LHC collider at 10 TeV centre-of-mass energy has been studied. The aim is to investigate the possibility to isolate a known Standard Model process to be used as reference for the measurement of the detector performance for the search of the Higgs Boson produced via Vector Boson Fusion. The signal to background ratio has been estimated considering only the dominant sources of background.

This document reports the first year of activity of the VBSCan COST Action network, as summarised by the talks and discussions happened during the VBSCan Thessaloniki 2018 workshop. The VBSCan COST action is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

The discovery of the neutrino by Reines & Cowan in 1956 revolutionised our understanding of the universe at its most fundamental level and provided a new probe with which to explore the cosmos. Furthermore, it laid the groundwork for one of the most successful and widely used neutrino detection technologies to date: the liquid scintillator detector. In these detectors, the light produced by particle interactions propagates across transparent scintillator volumes to surrounding photo-sensors. This article introduces a new approach, called LiquidO, that breaks with the conventional paradigm of transparency by confining and collecting light near its creation point with an opaque scintillator and a dense array of fibres. The principles behind LiquidO's detection technique and the results of the first experimental validation are presented. The LiquidO technique provides high-resolution imaging that enables highly efficient identification of individual particles event-by-event. Additionally, the exploitation of an opaque medium gives LiquidO natural affinity for using dopants at unprecedented levels. With these and other capabilities, LiquidO has the potential to unlock new opportunities in neutrino physics, some of which are discussed here.

This document summarises the talks and discussions happened during the VBSCan Mid-Term Scientific Meeting workshop. The VBSCan COST action is dedicated to the coordinated study of vector boson scattering (VBS) from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

The CMS experiment will take data at the LHC proton proton collider, running at a centre-of-mass energy of 14 TeV. The CMS electromagnetic calorimeter (ECAL) is made of about 76000 PbWO4 crystals. The possibility to use the measured events for the physics studies relies on the robustness and efficiency of the triggering procedure. In this report the ElectronPhoton package of the ORCA framework (Object oriented Reconstruction for CMS Analysis) is presented and results from full simulation studies of the High-Level Trigger procedures to reconstruct and select electrons and photons are given.

In this paper we present the features and the expected performance of the re-designed CMS simulation software, as well as the experience from the migration process. Today, the CMS simulation suite is based on the two principal components - Geant4 detector simulation toolkit and the new CMS offline Framework and Event Data Model. The simulation chain includes event generation, detector simulation, and digitization steps. With Geant4, we employ the full set of electromagnetic and hadronic physics processes and detailed particle tracking in the 4 Tesla magnetic field. The Framework provides "action on demand" mechanisms, to allow users to load dynamically the desired modules and to configure and tune the final application at the run time. The simulation suite is used to model the complete central CMS detector (over 1 million of geometrical volumes) and the forward systems, such as Castor calorimeter and Zero Degree Calorimeter, the Totem telescopes, Roman Pots, and the Luminosity Monitor. The designs also previews the use of the electromagnetic and hadronic showers parametrization, instead of full modelling of high energy particles passage through a complex hierarchy of volumes and materials, allowing significant gain in speed while tuning the simulation to test beam and collider data. Physics simulation has been extensively validated by comparison with test beam data and previous simulation results. The redesigned and upgraded simulation software was exercised for performance and robustness tests. It went into Production in July 2006, running in the US and EU grids, and has since delivered about 60 millions of events.

Insight into the electroweak (EW) and Higgs sectors can be achieved through measurements of vector boson scattering (VBS) processes. The scattering of EW bosons are rare processes that are precisely predicted in the Standard Model (SM) and are closely related to the Higgs mechanism. Modifications to VBS processes are also predicted in models of physics beyond the SM (BSM), for example through changes to the Higgs boson couplings to gauge bosons and the resonant production of new particles. In this review, experimental results and theoretical developments of VBS at the Large Hadron Collider, its high luminosity upgrade, and future colliders are presented.

The calibration and monitoring system constructed for the HARP experiment scintillator-based time of flight system is described. It is based on a Nd-Yag laser with passive Q-switch and active/passive mode-locking, with a custom made laser light injection system based on a bundle of IR monomode optical fibers. A novel ultrafast InGaAs MSM photodiode, with 30 ps risetime, has been used for the laser pulse timing . The first results from the 2001–2002 data taking are presented, showing that drifts in timing down to about 70 ps can be traced.

In the data collected so far at the LHC collider, the CMS experiment measured a strong evidence for a new resonance at an invariant mass of about 125 GeV. The analysis is outlined in its most important aspects, as well as the main results obtained. In fact, this final state allows for a very precise determination of the signal cross-section, and for the investigation of the tensor structure of the resonance decay. Results show that the behaviour of the new particle is compatible with the expectations for a Standard Model Higgs boson.

IMCP is an R&D project aimed at the exploitation of secondary emission of electrons from the surface of microchannel plates (MCP) for fast timing of showers in high rate environments. The usage of MCPs in “ionisation” mode has long been proposed and is used extensively in ion time-of-flight mass spectrometers. What has not been investigated in depth is their use to detect the ionizing component of showers. The fast time resolution of MCPs exceeds anything that has been previously used in calorimeters and, if exploited effectively, could aid in the event reconstruction at high luminosity colliders. Results from tests with electrons with energies up to 150 GeV of MCP devices with different characteristics will be presented, in particular detection efficiency and time resolution.

Results of theStandard Model Higgs boson searches at CMS and ATLAS are presented, in the final state characterised by the presence of two W bosons in the detector.The analyses are performed on the full dataset collected by the LHC at 7 TeV and 8 TeV of centre-of-mass energy and span different Higgs production mechanisms as well as different decay modes of the W bosons.A resonance at low mass is observed with a significance of around 4 σ by both the experiments, compatible with the Standard Model expectations for the Higgs boson behaviour.First measurements of its properties are reported.

The production of Z bosons via Vector Boson Fusion at the LHC collider at 10 TeV centre-of-mass energy has been studied. The aim is to investigate the possibility to isolate a known Standard Model process to be used as reference for the measurement of the detector performance for the search of the Higgs Boson produced via Vector Boson Fusion. The signal to background ratio has been estimated considering only the dominant sources of background.

Prospective analyses are presented with the CMS experiment at the LHC for the search of the Standard Model Higgs boson produced in vector boson fusion processes, pp→qqH, where the Higgs boson is accompanied by two high rapidity jets. Results are discussed for the H→γγ, H→WW and H→ττ decay channels for an integrated LHC luminosity of 30 fb−1. For a Higgs boson mass MH in the range 115 to 140 GeV/c2, an observation with a significance above 2 standard deviations is expected in the H→γγ channel, and above 3 standard deviations in the H→ττ channel. The H→WW channel offers a discovery reach above 5 sigma in the range 140<MH<200 GeV/c2. A new complete strategy is presented for the control of systematics and early searches at very low luminosities of O(1 fb−1).

An exploratory study has been performed in order to assess the possibility of probing the symmetry breaking mechanism through the VV fusion process using the CMS detector. A model independent analysis was carried out with no assumption on the mechanism restoring the unitarity in the scattering amplitude and without any degrees of freedom beyond the SM. In order to explore the sensitivity of the analysis method to an heavy Higgs resonance, we analyzed a data set produced using an Higgs boson mass of 500 GeV. Moreover, in order to consider the VV fusion cross section in a region where no resonances are present, a sample corresponding to the no‐Higgs scenario, that in the SM is equivalent to a very high Higgs mass, has been also studied.

During summer 2006, 9 supermodules of the CMS electromagnetic calorimeter (ECAL) have been exposed to an electron beam at the CERN SPS north area facility. Each supermodule contains 1700 crystals. The intercalibration coefficients of the different channels have been measured for each supermodule. The reproducibility of the intercalibration has been tested by measuring a supermodule twice. The intercalibration coefficients obtained in the electron beam have also been compared with those obtained with cosmic ray muons.

Since the beginning of the millennium, High Energy Physics research institutions like CERN and INFN pioneered several projects aimed at exploiting the synergy among computing power, storage and network resources, and creating an infrastructure of distributed computing on a worldwide scale. In the year 2000, after the Monarch project [http://monarc.web.cern.ch/MONARC/], DataGrid started [http://eu-datagrid.web.cern.ch/eu-datagrid/] aimed at providing High Energy Physics with the computing power needed for the LHC enterprise. This program evolved into the EU DataGrid project, that implemented the first actual prototype of a Grid middleware running on a testbed environment. The next step consisted in the application to the LHC experiments, with the LCG project [http://lcg.web.cern.ch/LCG/], in turn followed by the EGEE [http://www.eu-egee.org/] and EGEE II programs.

Abstract We report on a consistent comparison between techniques of quantum and classical machine learning applied to the classification of signal and background events for the Vector Boson Scattering processes, studied at the Large Hadron Collider installed at the CERN laboratory. Quantum machine learning algorithms based on variational quantum circuits are run on freely available quantum computing hardware, showing very good performances as compared to deep neural networks run on classical computing facilities. In particular, we show that such kind of quantum neural networks are able to correctly classify the signal with an Area Under the characteristic Curve (AUC) that is very close to the one obtained with the corresponding classical neural network, but employing a much lower number of resources, as well as less variable data in the training set. Albeit giving a proof-of-principle demonstration with limited quantum computing resources, this work represents one of the first steps towards the use of near term and noisy quantum hardware for practical event classification in High Energy Physics experiments.

Abstract We report on a consistent comparison between techniques of quantum and classical machine learning applied to the classification of signal and background events for the Vector Boson Scattering processes, studied at the Large Hadron Collider installed at the CERN laboratory. Quan- tum machine learning algorithms based on variational quantum circuits are run on freely available quantum computing hardware, showing very good performances as compared to deep neural networks run on classical computing facilities. In particular, we show that such kind of quantum neural networks are able to correctly classify the signal with an Area Under the characteristic Curve (AUC) that is very close to the one obtained with the corresponding classical neural network, but employ- ing a much lower number of resources, as well as less variable data in the training set. Albeit giving a proof-of-principle demonstration with limited quantum computing resources, this work represents one of the first steps towards the use of near term and noisy quantum hardware for practical event classification in High Energy Physics experiments.

The electromagnetic calorimeter (ECAL) of the CMS detector contains about 76000 lead-tungstate (PbWO4) crystals. This calorimeter has an excellent intrinsic energy resolution, below 0.5% above 120 GeV. At high energies, the major contribution to the resolution is given by the inter-calibration of the channels that compose the detector. It is therefore important to keep this contribution below 0.5%. To reach such a precision, several techniques have been envisaged, both before and after the start of the experiment. During the data taking, in particular, physics channels will be used to equalize the response of all the PbWO4 crystals of the detector. At the very beginning the symmetry of the minimum bias deposition, together with the Z invariant mass reconstruction, will provide a first estimate of the calibration coefficients, that will be eventually determined by using the E/p ratio of isolated electrons, mainly coming from the W decay. The π 0 and η 0 decays will also help determining the calibration coefficients.

This document summarises the talks and discussions happened during the VBSCan Split17 workshop, the first general meeting of the VBSCan COST Action network. This collaboration is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

The scattering of vector bosons (VBS) happens at the Large Hadron Collider when, in a proton collision, two vector bosons radiate from the interacting quarks and scatter.The VBS process is of great interest because of its intimate relationship with the foundations of the Standard Model of the fundamental interactions, since its unitarity is granted by the EW symmetry breaking.Therefore studying the VBS gives access to the EWSB in an orthogonal way with respect to the Higgs boson physics.Despite being among the rarest processes studied so far, the first results have already been published by the ATLAS and CMS Collaborations, triggering the experimental and theory communities in adding more final states on the measurement side, and pursuing more precision on the theory one.On the long term, the high-luminosity LHC will deliver a dataset of unprecendented size, that will allow to fully exploit the VBS topology, which is nowadays still fully dominated by the statistical uncertainties.

The CMS Collaboration used the dataset delivered by the Large Hadron Collider in the past years to study rare processes characterised by the simultaneous production of several vector bosons in the proton collisions.This report presents recent results attained in this domain, ranging from inclusive multi-boson final states, to double parton scattering and vector boson scattering.

This document reports the first year of activity of the VBSCan COST Action network, as summarised by the talks and discussions happened during the VBSCan Thessaloniki 2018 workshop. The VBSCan COST action is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

This document reports the first year of activity of the VBSCan COST Action network, as summarised by the talks and discussions happened during the VBSCan Thessaloniki 2018 workshop. The VBSCan COST action is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

This document reports the first year of activity of the VBSCan COST Action network, as summarised by the talks and discussions happened during the VBSCan Thessaloniki 2018 workshop. The VBSCan COST action is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

The CMS object oriented Geant4-based program is used to simulate the complete central CMS detector (over 1 million geometrical volumes) and the forward systems such as the Totem telescopes, Castor calorimeter, zero degree calorimeter, Roman pots, and the luminosity monitor. The simulation utilizes the full set of electromagnetic and hadronic physics processes provided by Geant4 and detailed particle tracking in the 4 tesla magnetic field. Electromagnetic shower parameterization can be used instead of full tracking of high-energy electrons and positrons, allowing significant gains in speed without detrimental precision losses. The simulation physics has been validated by comparisons with test beam data and previous simulation results. The system has been in production for almost two years and has delivered over 100 million events for various LHC physics channels. Productions are run on the US and EU grids at a rate of 3-5 million events per month. At the same time, the simulation has evolved to fulfill emerging requirements for new physics simulations, including very large heavy ion events and a variety of SUSY scenarios. The software has also undergone major technical upgrades. The framework and core services have been ported to the new CMS offline software architecture and event data model. In parallel, the program is subjected to ever more stringent quality assurance procedures, including a recently commissioned automated physics validation suite