The LHC has observed a number of potentially interesting deviations from the predictions of the Standard Model in the flavor sector, in particular in the decays of B-mesons. This talk offers a review of the experimental status of these anomalies, and their implications for physics beyond the Standard Model and associated signatures at the LHC and beyond.
A review of the status of the Unitarity Triangle Fits by the CKMFitter and UTfit collaborations. Current averages of charm mixing data are discussed
Review the theoretical basis of neutral meson mixing and CPV in mixing and decay. Discuss the constraints imposed on New Physics models based on mixing and CPV measurements.
This talk will address the theoretical basics and the latest developments aimed at describing collective dynamics in high-energy collisions. The focus should be exclusively on final-state-effects driven collectivity, such as those employed in hydrodynamic modelling and alike (as initial state driven effects will be covered in another session). The relevance and applicability of hydrodynamics...
A general overview of SUSY implementations interesting for LHC - Natural SUSY, Split SUSY, etc.
Significant parts of the original data and of derived data sets from the LHC experiments are openly available to scientists, educators, students and the general public on the CERN Open Data portal opendata.cern.ch, and on experiment-specific portals.
The latest data releases and some of their applications will be reviewed, with focus on both research (up to physics papers) and educational...
As the LHC reaches a mature and stable phase of running, new search techniques are called for in order to ensure that the maximum possible information is extracted from the data. This talk describes the most recent innovations in this area, including new kinematic variables, event geometry, and applications of machine learning to the LHC.
Problem solving workshop hackathons are becoming more and more common in the world of academia. CERN and the LHC experiments have been involved in these type of projects for many years, bringing together data scientists, coders and innovators, from extremely diverse backgrounds. This talk offers a review of the most recents hackathon project and their impact on the world of high energy...
The talk will present, by selected examples, how to explain the LHC physics to a general public. It will also show how the communication strategy depends strongly on the specific target.
[NB: 15 minutes talk plus 2 minutes of questions]
Two recent outreach projects are making use of public communities to enhance and build upon the first phases setup by physicists. “HiggsHunters” asked the public to search for displaced vertices in event displays, during which time a pool of trusted members arose in the associated discussion. The data this generated is now being analysed by schoolchildren, through which they can both learn the...
During the next 5 years a great number of laboratories all around the world will be involved on the upgrading of the 4 principal experiments at CERN (ATLAS, CMS, LHCb, ALICE). The ATLAS Bologna group, which collaborates with the Pixel Detector's DAQ (Data AcQuisition), in the last 2 years has developed a prototype of a new board named PILUP (PIxel detector high Luminosity UPgrade); this board...
The LHCb experiment at CERN operates a high precision and robust tracking system to reach its physics goals, including precise measurements of CP-violation phenomena in the heavy flavour quark sector and searches for New Physics beyond the Standard Model. The track reconstruction procedure is performed by a number of algorithms. One of these, PatLongLivedTracking, is optimised to reconstruct...
Measurements of anti-deuterons in collider experiments can help to
reduce systematic uncertainties in indirect searches for dark matter.
Two predominant unknowns in these searches are the production of
secondary anti-deuterons in the cosmos from spallation processes, and
anti-deuteron production from annihilating dark matter.
LHCb is a forward spectrometer on the LHC ring, designed to...
The measurement the of W+c production cross-section provides an
opportunity to directly access the strange quark content of the proton
at the electroweak scale.
We focus on W → lν and c → D * as probes of W+c since both, W-
boson and D-Meson, can be measured with good accuracy by the CMS-
detector. Further the fragmentation of charm quarks into D-mesons is
well measured. The data taken by the...
ATLAS electron and photon triggers covering transverse energies from 5 GeV to several TeV are essential to record signals for a wide variety of physics: from Standard Model processes to searches for new phenomena. To cope with ever-increasing luminosity and more challenging pile-up conditions at a centre-of-mass energy of 13 TeV, the trigger selections need to be optimized to control the rates...
The aim of the ATLAS Forward Proton (AFP) detector system is the measurement of protons scattered diffractively or electromagnetically at very small angles. The full two-arm setup (on both sides of the interaction point), which allows measurements of processes with two forward protons: central diffraction, exclusive production, and photon-induced interactions, was installed during the...
The current ATLAS model of Open Access to recorded and simulated data offers the opportunity to access datasets with a focus on education, training and outreach. This mandate supports the creation of platforms, projects, software, and educational products used all over the planet. We describe the overall status of ATLAS Open Data (http://opendata.atlas.cern) activities, from core ATLAS...
The ALICE experiment at the Large Hadron Collider (LHC) is dedicated to study the properties of the Quark-Gluon Plasma (QGP), a de-confined partonic state of strongly-interacting matter formed in relativistic heavy-ion collisions. Heavy quarks (charm and beauty), produced by parton-parton hard scatterings in the early stages of such collisions, are effective probes to study the QGP, as they...
Precise calibration and monitoring of the CMS electromagnetic calorimeter (ECAL) is a key ingredient in achieving the excellent ECAL performance required by many physics analyses employing electrons and photons. This poster describes the methods used to monitor and inter-calibrate the ECAL response, using physics channels such as W/Z boson decays to electrons and pi0/eta decays to photon...
A description of the phase transition to the formation of a strong interacting color-deconfined state of QCD matter is given by the string percolation model which is base on two-dimensional (2D) continuum percolation of the projection of color fields.The created systems in pp and pA collisions are a non-thermalized system which departs from the thermal equilibrium limit. In the present work,...
The energy and mass of jets measured with the ATLAS detector are calibrated through a multi-step process. In the last step of this chain, known as the residual in-situ calibration, events with a well-measured feature, such as the pT of a photon or the mass of a top, are used as reference to correct the calibration scale in-situ and estimate its uncertainty.
In order to constrain the Jet...
The identification of jets originated from b quarks is crucial for a broad range of physics analyses, from the standard model precision measurements to the new physics searches. Various b tagging algorithms exist at CMS and are further developed with the use of the machine learning techniques. The poster focuses on the studies with the comparison between the proton-proton collision data and...
The LHC plans a series of upgrades culminating in the High Luminosity LHC (HL-LHC) which will have an average luminosity 5-7 times larger than the design LHC value. The electronics of the hadronic Tile Calorimeter (TileCal) will undergo a substantial upgrade to accommodate to the HL-LHC parameters. In particular, TileCal will undergo a major replacement of its on- and off-detector...
Neutrinos mass generation is needed to explain neutrino oscillations. Seesaw mechanisms offer a solution and motivate searches for heavy neutral leptons in either opposite-sign or same-sign leptons final states. This contribution discusses the challenging backgrounds for same-sign final states, either due to incorrectly identified jets as leptons or to mismesureaments of the electron charge.
The design of a muon detector and first-level muon trigger system for the FCC-hh baseline experiment is presented. Drift-tube chambers operated with Ar:CO2 (93:7) gas mixture at 3 bar provide a robust and cost effective solution for precise track point and angle measurement over large areas (about 1200 m2) with the required resolution of better than 50 µm and 70 µrad, respectively. To achieve...
The High Luminosity LHC (HL-LHC) will operate at a collider instantaneous luminosity up to 7.5x1034 cm-2s-1, approximately five times larger than the limit reached during the present LHC run. For the CMS experiment, this corresponds to an average pile-up of up to 200 events per crossing in the interaction region of the detector, and an integrated luminosity of up to 4000 fb-1 over 10 years of...
We exploit the large W production at LHC run-2 to perform the first ATLAS search for right-handed neutrinos in the mass range 4-20 GeV. We probe unexplored regions of mixing strengths in which right-handed neutrinos can explain neutrino masses and matter-antimatter asymmetry and feature decay lengths of 1-100 mm, providing the striking signature of a displaced decay. The prompt lepton from the...
Energy-frontier DIS can be realised at CERN through an energy recovery linac that would produce 60 GeV electrons to collide with the High Luminosity or High Energy LHC (LHeC) or eventually the FCC hadron beams (FCC-eh). It would deliver electron-lead collisions with centre-of-mass energies in the range 0.3-2.2 TeV per nucleon, and luminosities exceeding $5 \times 10^{32}$ cm$^{−2}$s$^{−1}$. In...
To extend the LHC physics program, it is foreseen to operate the LHC in the future with an unprecedented high luminosity. To maintain the experiment's physics potential in the harsh environment of this so-called phase-2, the detector will be upgraded. At the same time the detector acceptance will be extended and new features such as a L1 track trigger will be implemented. Simulation studies...
The work is devoted to the result of the creating a first module of the 1-st phase of the data processing center at the Joint Institute for nuclear research for modeling and processing experiments carried out on the test installations of the Large Hadron Collider. The issues related to handling the enormous data flow from the LHC experimental installations and troubles of distributed storages...
We report on a preliminary study of the production of f$_{0}$(980)$\rightarrow \pi^{+}\pi^{-}$ at mid-rapidity ($\vert y \vert$~$<$~0.5) performed with the ALICE detector at the LHC in minimum bias pp collisions at the centre-of-mass energy $\sqrt{\mathit{s}}$ = 5.02 TeV. The f$_{0}$(980) signal extraction is challenging due to the large background from correlated $\pi^{+}\pi^{-}$ pairs from...
The study of strange hadronic resonances in pp collisions contributes to the study of strangeness production in small systems. Measurements in pp collisions constitute a reference for the study in larger colliding systems and provide constraints for tuning QCD-inspired event generators. Since the lifetimes of short-lived resonances such as $K^{*}(892)^{\pm}$ ($\tau \sim 4$ fm/$c$) are...
Single muon triggers are crucial for the physics programmes as hadron collider experiments. To be sensitive to electroweak processes, single muon triggers with transverse momentum thresholds down to 20 GeV and dimuon triggers with even lower thresholds are required. In order to keep the rates of these triggers at an acceptable level these triggers have to be be highly selective, i.e. they must...
In spite of the recent progress in both theoretical and experimental studies many aspects of proton-proton (pp) and proton-nucleus (pA) collisions still require a detail investigation. At high collision energies, the probability of simultaneous scatterings of different pairs of partons, contributing to the same inelastic event, has to be considered. In particular, *double parton...
The H $\to$ ZZ $\to$ 4$\ell$ decay channel ($\ell = e, \mu$) is one of the most important channels for studies of properties of the Higgs boson since it has a large signal-to-background ratio due to the complete reconstruction of the final state decay objects and excellent lepton momentum resolution. Measurements performed using this decay channel and Run 1 data include, among others, the...
Although the observed 125 GeV boson is compatible with the SM Higgs boson, the existence of non-SM properties is not excluded due to the relatively large uncertainties. There is extensive evidence for the existence of dark matter. Invisible Higgs decay modes are realized in models allowing interactions between the Higgs boson and dark matter, for example, "Higgs-portal" models. Searches for...
The reconstruction of high-momentum muons presents peculiar aspects due to the increasing probability of showering in the detector material, and is critically dependent on the relative alignment of the muon chambers with the inner tracker and among themselves. On the other hand, high-momentum muons constitute a clean signature for the decay of new hypothesised high-mass Z’ or W’ bosons, or...
Results from the Dijet Resonance Search using data from 2016 and 2017 running will be shown, with emphasis on narrow resonances, for resonance masses above 1.6 TeV and a variety of new physics models used for the interpretation of the experimental results. The traditional method of estimating the QCD background is used, employing a parametrization for the background and an empirical fit of the...
Results from the Dijet Resonance Search using data from 2016 and 2017 running will be shown, with emphasis on wide resonances, for resonance masses above 1.6 TeV and focusing on simplified models of Dark Matter for the interpretation of the experimental results. A new method of estimating the QCD background is used, employing a data-driven methodology where events in a background dominated...
The Fast TracKer (FTK) system is a track reconstruction processor able to perform full event tracking synchronously with the ATLAS Level 1 trigger acceptance rate.
The high quality tracks produced by the system will be used by the High Level Trigger algorithms to improve the identification of physics objects such as b-jets and taus, as well as to help mitigating the effects of pileup. The...
A key ingredient of the data taking strategy used by the LHCb experiment at CERN in Run 2 is the novel real-time detector alignment and calibration. Data collected at the start of the fill are processed within minutes and used to update the alignment, while the calibration constants are evaluated hourly. This is one of the key elements which allow the reconstruction quality of the software...
For Run 2 of LHCb data taking, the selection of PID calibration samples is implemented in the high level trigger. A further processing is needed to provide calibration samples used for the determination the PID performance, which is achieved through a centralised production that makes highly efficient use of LHCb computing resources. This poster presents the major steps of the production...
Several new physics models that extend the Standard Model require the existence of Long-Lived Particle (LLP) as a solution for the problems like Dark Matter and Naturalness. The new ATLAS Phase-II setup with its huge statistics and updated detectors offers an opportunity to probe the yet unexplored region of the phase space. For muon spectrometer based searches neutral LLP decaying to...
The LUCID detector is the main luminosity provider of the ATLAS experiment and the only one able to provide a reliable luminosity determination in all beam configurations, luminosity ranges and at bunch-crossing level.
LUCID was entirely redesigned in preparation for Run 2: both the detector and the electronics were upgraded in order to cope with the challenging conditions expected at the LHC...
Reliable and performant heavy flavour identification is of prime importance for the physics program of the CMS experiment. During the last years the CMS collaboration has dedicated a considerable effort to improve and expand its capabilities in this sector by applying several machine learning techniques well established in industry, but still experimental in HEP. The poster will focus on a...
An important test of the Standard Model (SM) electroweak symmetry breaking sector is the measurement of the Higgs self-interactions. Sensitivity to the Higgs self-coupling for mH = 125 GeV is evaluated through the measurement of the non-resonant di-Higgs production final states. The considered decay channels are HH → VVbb, where V=W,Z. For the non-resonant SM signal in an ideal detector...
Tau leptons play an important role in many Standard Model and Beyond the Standard Model physics processes that are being investigated at the LHC. This poster details measurements of the performance of the reconstruction and identification of hadronic tau lepton decays using the ATLAS detector. The measurements include the performance of the identification, trigger, energy calibration and decay...
A recent measurement of ttbar inclusive production cross section is presented using data collected by CMS at 13 TeV. The measurement focuses on final states with two leptons.
The top quark pair production cross section (stt) is measured in pp collisions at a center-of-mass energy of 5.02 TeV. The analyzed data have been collected by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 27.4 /pb. The measurement is performed by analyzing events with at least one charged lepton. The measured cross section is 69.5 +/- 8.4 pb. The result is...
The precise evaluation of the tracking efficiencies is a crucial element for many physics analysis, especially those aiming at measuring production cross sections or branching fractions. In the LHCb experiment, several data-driven approaches have been conceived and continuously improved in order to provide a precise evaluation of the tracking efficiencies. They are mostly based on clean...
The inclusive cross-section for tW production in proton-proton collisions at $\sqrt{s} = 13$ TeV is measured of a dataset corresponding to an integrated luminosity of 35.9 fb$^{-1}$ collected by the CMS experiment. The measurement is performed in events with one electron and one muon, and exploits kinematic differences between the signal and the dominating $t\bar{t}$ background through the use...
The W boson is a short lived particle which does not interact strongly. Thus its production rate measured in lepton decay channels can be compared between lead-lead and proton-proton collisions as a direct test of both binary collision scaling and the possible modification of parton distribution functions (nPDF) due to nuclear effects. The ATLAS detector has recorded 0.49 nb-1 of lead-lead...
The production of jets in association with a W or a Z boson in proton-proton collision is an important process to study QCD in multi-scale environments. Measurements of W/Z boson production in association with heavy flavour quarks provide experimental constraints to improve the theoretical description of these precesses, which suffer from larger uncertainties than in the inclusive jet case.
A...
We show plans and status of a proposed search for milli-charged particles produced at the LHC. The experiment, milliQan, is expected to obtain sensitivity to charges of between 0.1e and 0.001e for masses in 0.1 - 100 GeV range. The detector is composed of 3 layers of 80 cm long plastic scintillator arrays read out by PMTs sensitive to single photo-electrons. It would be installed in an...
The performance of muon identification and isolation efficiencies in CMS has been studied on data collected in pp collisions at 13 TeV at the LHC on the full 2017 dataset. The efficiencies have been computed with the tag-and-probe method, in different periods of data taking. Results obtained using data are compared with Monte-Carlo predictions.
Muon reconstruction and identification play a fundamental role in many analyses of central importance in the LHC run-2 Physics programme. The algorithms and the criteria used in ATLAS for the reconstruction and identification of muons with transverse momentum from a few GeV to the TeV scale will be presented. Their performance is measured in data based on the decays of Z and J/ψ to pair of...
The ATLAS muon spectrometer is an essential component of the detector, providing trigger and track reconstruction for every physics process containing high-energy muons. This is accomplished using several types of tracking sub-detectors, providing both a very fast trigger system and an accurate track reconstruction. A dedicated toroidal magnetic field, in order to measure the muon momentum, is...
The LHC delivers an unprecedented number of proton-proton collisions to its experiments. In kinematic regimes first studied by earlier generations of collider experiments, the limiting factor to more deeply probing for new physics can be the online and offline computing, and offline storage, requirements for the recording and analysis of this data. In this contribution, we describe a strategy...
The collisions of Partially Stripped Ions (PSI) with laser light to produce high intensity gamma-ray beams are the backbone of the Gamma Factory (GF) initiative.
The source, if realised at LHC, could significantly push up the intensity limits of the presently operating ones, reaching the flux of the order of $10^{17}$ photons/s, in the particularly interesting gamma-ray energy domain of 1 to...
The electromagnetic processes of annihilation of $(e^+ e^-)$ pairs, generated in high-energy nucleus-nucleus and hadron-nucleus collisions, into heavy lepton pairs are theoretically studied in the one-photon approximation, using the technique of helicity amplitudes . For the process $e^+e^- \rightarrow \mu^+\mu^-$, it is shown that -- in the case of the unpolarized electron and positron -- the...
Important analyses of the core LHCb physics program rely on calorimetry to identify photons, high-energy neutral pions and electrons. For this purpose, the LHCb calorimeter system is composed of a scintillating pad plane, a preshower detector, an electromagnetic and a hadronic sampling calorimeters. The interaction of a given particle in these detectors leaves a specific signature. This is...
The LHCb collaboration has recently reported evidence of two pentaquark states [1]. We have constructed a classification scheme for pentaquark states and tried to describe them as compact objects [2]. The hidden-charm pentaquark states have been also described as meson-baryon molecules with coupled channels for D¯(∗)Λc
and D¯(∗)Σ(∗)c [3] and recently, for the first time, we have discussed...
The Tile Calorimeter (TileCal) of the ATLAS experiment at the LHC is the central hadronic calorimeter designed for the reconstruction of hadrons, jets, tau-particles and missing transverse energy. TileCal is a scintillator-steel sampling calorimeter and it covers the region of pseudorapidity < 1.7. The scintillation light produced in the scintillator tiles is transmitted by wavelength shifting...
Many physics analyses using the Compact Muon Solenoid (CMS) detector at the LHC require accurate, high resolution electron and photon energy measurements. Particularly important are decays of the Higgs boson resulting in electromagnetic particles in the final state, as well as searches for very high mass resonances decaying to energetic photons or electrons. Following the excellent performance...
CMS-HF Calorimeters have been upgraded within the Phase I upgrade program of the CMS. These upgrades that were finalized during EYETS16/17 involved the replacement of the single anode PMTs with the 4-anode PMTs and the associated front-end electronics to read out the signals coming from these PMTs. Four-anode PMTs were more effective in reducing the noise in the HF detectors due to the window...
The ATLAS muon spectrometer comprises excellent muon trigger capabilities and high muon momentum resolution up to the TeV scale. Yet, in a small region between the barrel and end-cap parts of the muon spectrometer, a non-negligible muon trigger rate from charged particle not emerging from the pp interaction point has been observed. To prevent such fake triggers, the end of the inner ring of...
The discovery made at the Large Hadron Collider (LHC) has revealed that the spontaneous symmetry breaking mechanism is realised in a gauge theory such as the Standard Model (SM) by at least one Higgs doublet. However, the possible existence of other scalar bosons cannot be excluded. We analyze signatures extensions of the SM, characterized by an extra representations of scalars, in view of the...
In late 2017, the ALICE collaboration recorded data from Xe-Xe collisions at the unprecedented energy in AA systems of $\sqrt{s_{\rm{NN}}} = 5.44$ TeV. The $p_{\rm T}$-spectra at mid-rapidity ( $|y| < 0.5$ ) of pions, kaons and protons are presented.
The final $p_{\rm T}$-spectra are obtained by combining independent analyses with the Inner Tracking System (ITS), the Time Projection Chamber...
Cathode Strip Chambers (CSC) are a crucial component of the CMS endcap muon system which will operate throughout the lifetime of the LHC and beyond, during the HL-LHC running. We present an analysis of the expected CSC performance in a HL-LHC like environment as well as studies of CSC detector longevity over the lifetime of the HL-LHC.
Big volumes of data are collected and analysed by LHC experiments at CERN. The success of this scientific challenges is ensured by a great amount of computing power and storage capacity, operated over high performance networks, in very complex LHC computing models on the LHC Computing Grid infrastructure. Now in Run-2 data taking, LHC has an ambitious and broad experimental programme for the...
Most searches for physics beyond the Standard Model at ATLAS study prompt signatures where particle tracks are associated to the primary interaction vertex. Since these searches have not found any evidence of new physics yet, it becomes more and more important to consider long-lived signatures that are much harder to probe. The reconstruction algorithms commonly used at ATLAS are highly...
A search for new charged massive gauge bosons, called W’, decaying to tb, is performed with the ATLAS detector in the decay channel leading to final states with an electron or muon, 2 or 3 jets and missing transverse momentum. This search uses a dataset corresponding to an integrated luminosity of 36.1 fb$^{−1}$ of $pp$ collisions produced at the LHC and collected during 2015 and 2016. The...
A search for dark matter pair production in association with a Z' boson in pp collisions, at 13 TeV, using 36.1 fb$^{-1}$ of LHC pp collision data recorded with the ATLAS detector is presented. Events are characterised by large missing transverse momentum and a hadronically decaying vector boson reconstructed as either a pair of small-radius jets, or as a single large-radius jet with...
Search for events with large missing transverse momentum (MET) recoiling against a SM particle is a probe for detecting Dark Matter (DM) at the LHC. The discovery of the Higgs boson h opens a new opportunity through the h+MET signature, with h->bb being the most probable decay channel. Depending on the amount of MET in the event, the Higgs candidate is reconstructed as a system of two b-tagged...
Dark Matter comprises a significant part of the visible Universe. Despite a solid cosmological evidence, its particle nature and properties is still to be unraveled. Looking for the production of Dark Matter particles at particle colliders can shed light on the mystery of Dark Matter. The signature of this search is a pair of quarks coming from the decays of the Standard Model W and Z bosons,...
The MoEDAL experiment addresses a decades-old issue, the search for an elementary magnetic monopole, first theorised in 1931 by Dirac to explain electric charge quantisation. Since then it was showed that magnetic monopoles occur naturally in grand unified theories as solutions of classical equations of motion.
The dedicated experiment can enjoy a new energy regime opened at the LHC allowing...
The standard model (SM) has been very successful in describing the phenomenology of the electroweak and strong interactions. The discovery of a Higgs boson consistent with the SM prediction at the LHC in 2012 was a major achievement. However, the SM does not answer fundamental questions. Therefore, great efforts have been made by experimental groups in order to search for new physics....
A search for pair and single production of vector-like quarks T and B with a leptonically decaying Z boson is presented. The data were collected in pp collisions at 13 TeV with the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 36.1 fb$^{-1}$. A high momentum Z boson is reconstructed from a same-flavor pair of leptons, which carry opposite charge, and...
Results of a search for the pair production of highly collimated groupings of photons (photon jets) in the ATLAS detector at the LHC are reported, using data from proton-proton collisions collected in 2015 and 2016 at a centre-of-mass energy of 13 TeV. Photon-jets can arise from the decay of new, highly boosted particles that are identified in the electromagnetic calorimeter as a single,...
A search is performed for a heavy resonance decaying to WZ in the fully leptonic channel. It is based on proton-proton collision data collected by the ATLAS experiment at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 36.1 fb$^{-1}$. Limits are set on the production cross section times branching ratio of a heavy vector particle produced either in...
The associated production of the Higgs boson with a pair of
top/anti-top quarks (ttH) is the only process providing the direct access to
the measurement of the Yukawa coupling between the Higgs boson and the top
quark. The presented results exploit the data collected during 2015 and 2016
by the ATLAS experiment during LHC collisions at a center-of-mass energy of
13 TeV. Multivariate...
A search for type III seesaw heavy leptons decaying into pairs of leptons, a pair of jets and large missing transverse energy is presented. The results reported here use the $pp$ collision data sample corresponding to 80.0 fb$^{−1}$ of integrated luminosity collected in 2015, 2016 and 2017 by the ATLAS detector at the LHC with a centre-of-mass energy of 13 TeV. The observation of neutrino...
A search for W'-boson production in the W' --> tb -->qqbb decay channel is presented using 36.1 fb$^{-1}$ of 13 TeV proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search is interpreted in terms of both a left-handed and right-handed chiral W' boson within the mass range 1-5 TeV. Identification of the hadronically decaying top...
The search for heavy Higgs bosons at the LHC represents an intense experimental program, carried out by the ATLAS and CMS collaborations, which includes the hunt for invisible Higgs decays and dark matter candidates. No significant deviations from the SM backgrounds have been observed in any of these searches, imposing significant constraints on the parameter space of different new physics...
Supersymmetry postulates the existence of a superpartner (sparticles) whose spin differs by one half unit from each corresponding Standard Model partner. The sector of sparticles with only electroweak interactions contains charginos, neutralinos, sleptons, and sneutrinos. Charginos and neutralinos are the mass eigenstates formed from the linear superpositions of the superpartners of the...
The instantaneous luminosity of the Large Hadron Collider at CERN will be increased up to a factor of five with respect to the design value by undergoing an extensive upgrade program over the coming decade. Such increase will allow for precise measurements of Higgs boson properties and extend the search for new physics phenomena beyond the Standard Model. The largest phase-1 upgrade project...
The first level hardware trigger system of the ATLAS experiment is expected to be fully upgraded for HL-LHC to stand the challenging performances requested with the increasing instantaneous luminosity. The Level-0 muon trigger system has to maintain or increase its data selection capability during HL-LHC, despite of the higher detector hit rate, cavern background and trigger rate. The...
The study of the multiplicity dependence of heavy-flavour production in pp collisions provides insight into their production mechanism and into the interplay between hard and soft processes in particle production. In addition, at the LHC energies, multiple parton interactions may also play a significative role in the heavy-flavour production.
In this contribution, we present the measurement...
Over the past several years, a team based around the ATLAS Experiment at CERN in Geneva has organised public engagement and education activities at a variety of non-scientific venues. These have included the Montreux Jazz Festival (Montreux, Switzerland), the Bluedot Festival (Jodrell Bank, UK), the WOMAD Festival (Charlton Park, UK), Moogfest (Durham, NC, USA), and the Sofia Music Weeks in...
To exploit the physics potential of the ATLAS experiment at the HL-LHC a trigger system with a first-level trigger rate of 1 MHz at a maximum latency of 10 µs will be employed. The TDCs of the current front-end electronics of the ATLAS muon drift-tube (MDT) chambers is incompatible with these trigger requirments and will have to be replaced by new TDCs. So will have the amplifier discriminator...
Social media is an essential tool for communicating particle physics results to a wide audience. This presentation will explore how the nature of social media platforms has impacted the content being shared across them, and the subsequent effect this has had on the user experience. The ATLAS Experiment has adapted its communication strategy to match this social media evolution, producing...
In 2017 the Large Hadron Collider (LHC) at CERN has provided an astonishing 50 fb-1 of proton-proton collisions at a center-of-mass energy of 13 TeV. The Compact Muon Solenoid (CMS) detector has been able to record 90.3% of this data. During this period, the CMS electromagnetic calorimeter (ECAL), based on 75000 scintillating PbWO4 crystals and a silicon and lead preshower, has continued...
The CMS experiment implements a sophisticated two-level triggering system composed of the Level-1, instrumented by custom-design hardware boards, and a software High Level Trigger. A new Level-1 trigger architecture with improved performance is now being used to maintain high physics efficiency for the more challenging conditions experienced during Run II. We present the performance of the...
The CMS experiment implements a sophisticated two-level triggering system composed of Level-1, instrumented by custom-design hardware boards, and a software High Level Trigger. A new Level-1 trigger architecture with improved performance is now being used to maintain high physics efficiency for the more challenging luminosity conditions experienced during Run II. The CMS muon detector contains...
The design and performance of the ATLAS Inner Detector (ID) trigger algorithms running online on the High Level Trigger (HLT) processor farm for 13 TeV LHC collision data with high pileup are discussed. The HLT ID tracking is a vital component in all physics signatures in the ATLAS Trigger for the precise selection of the rare or interesting events necessary for physics analysis without...
The CMS experiment implements a sophisticated two-level triggering system composed of the Level-1, instrumented by custom-design hardware boards, and a software High Level Trigger. A new Level-1 trigger architecture with improved performance is now being used to maintain high physics efficiency for the more challenging conditions experienced during Run II. The upgraded trigger benefits from an...
In the next years, the LHC accelerator will be upgraded with an increase of instantaneous and integrated luminosity, but at the same time also the data and the trigger rates will drastically increase. The ATLAS goal is to cope the big amount of data flow and at the same time trying to conserve the high muon efficiency. For this purpose the current innermost stations of the Muon Spectrometer...
The muon spectrometer of the ATLAS detector will undergo a major upgrade during the Long Shutdown 3, in order to cope with the operational conditions at the high-luminosity LHC. The trigger and readout electronics for the Resistive Plate Chambers (RPC), Thin Gap Chambers (TGC), and Monitored Drift Tube (MDT) chambers will be replaced to make them compatible with a new trigger scheme with...
The time-dependent CPV direct and mixing-induced asymmetries in
B^0->\pi \pi and
B_s ->K K decays have been measured at the LHCb experiment using data
collected during Run1 at centre-of-mass energies of 7 and 8 TeV,
corresponding to 3fb^-1.
The data set was also used for a measurement of time-integrated CP
asymmetries in B^0->K \pi and B_s->\pi K decays.
The results obtained supersede those...
During 2017, the Large Hadron Collider provided record-breaking integrated and instantaneous luminosities, resulting in huge amounts of data being provided with numbers of interaction per bunch crossing significantly beyond initial projections. In spite of these challenging conditions, the ATLAS Inner Detector (ID) track reconstruction continued to perform excellently, and this contribution...
Hadronic signatures are critical to the ATLAS physics program, and are used extensively for both Standard Model measurements and searches for new physics. These signatures include generic quark and gluon jets, as well as jets originating from b-quarks or the decay of massive particles (such as electroweak bosons or top quarks). Additionally, missing transverse momentum from non-interacting...
In addition to the main physics program based on proton-proton collisions, the ATLAS experiment also collects heavy-ion data with lead nuclei. Among these data sets, ultra-peripheral collisions provide a highly interesting class of events. They give an opportunity to study very rare processes involving two-photon exchange, such as light-by-light (LbyL) scattering - a phenomenon which was...
After the discovery of a Higgs boson, the measurements of its properties
are at the forefront of research. The determination of the associated
production of a Higgs boson and a pair of top quarks is of particular
importance as the ttH Yukawa coupling is large and can probe for physics
beyond the Standard Model.
The ttH production was analysed in various final states. The results are...
Many extensions of the Standard Model (SM) include particles that are neutral, weakly coupled, and long-lived that can decay to hadronic and leptonic final states. Long-lived particles (LLPs) can be detected at colliders as displaced decays from the interaction point (IP), or missing energy if they escape. ATLAS, CMS, and LHCb have performed searches at the LHC and significant exclusion limits...
By using the non-linear HEFT it is possible to study the WW, ZZ and WZ elastic
scattering at high energies relevant for the LHC. For most of the parameter space, the scattering is strongly interacting (with the MSM being a remarkable exception). Starting from one loop computations complemented with dispersion relations and the Equivalence Theorem, we obtain different unitarization methods...
The present CMS muon system operates three different detector types: in the barrel drift tubes (DT) and resistive plate chambers (RPC), along with cathode strip chambers (CSC) and another set of RPCs in the forward regions. In order to cope with increasingly challenging conditions various upgrades are planned to the trigger and muon systems. In view of the operating conditions at HL-LHC, it is...
We analyse two consequences of the relationship between collinear factorization and kt-factorization.
Firstly we show that the kt-factorization gives a fundamental justification for the choice of Q^2
done in the collinear factorization. Secondly, we show that in the collinear factorization there is an uncertainty
on this choice which will not be reduced by higher orders. This uncertainty is...
This parallel talk should give an overview of recent developments in the QCD phenomenology underlying general purpose Monte Carlo event generators, and the role of these developments concerning treatment of nuclei. The focus should be on soft particle production, and its function in determining the differences and similarities between the underlying dynamics of ultra relativistic proton-proton...
A general overview of the SUSY particle phenomenology of interest to the LHC
Overview of the phenomenology of the Higgs sector in SUSY theories.
Restricted meeting of the International Advisory Committee of the LHCP conference series
Many proposed extensions of the Standard Model contain particles with macroscopic life-times; decaying outside of the interaction point. Such particles pose unique challenges at the LHC. This talk provides an overview of the current status of these searches, as well as prospects for new experiments (e.g. MATHUSLA, FASER, SHIP, and CODEX-b) at the LHC which can close some interesting regions of...
Present fits of the b->sll Wilson coefficients treat the non-local charm contributions as a systematic theoretical uncertainty. The theoretical basis of the underlying non-local hadronic matrix elements is introduced, and ways toward constraining them in future fits are discussed.
Discussion of the impact of non-local QED corrections on observables of the decay B_s -> mu^+ mu^- and provide an outlook for their impact on other exclusive b->smumu transitions.
Discuss the problems in constructing New Physics models that fulfill the experimental constraints from the B anomalies and beyond.
This parallel talk should cover the latest theory developments related to the jet-quenching phenomenon and energy loss in nucleus-nucleus collisions with a focus on the lead-lead system. An attempt to interpret the latest HI results in the jet physics sector using a broad range of observables e.g. inclusive Raa, dijet asymmetry, jet fragmentation functions and sensitivity of jet substructure...
Discuss the models proposed to account for the spectroscopy of exotic states, their predictions and the prospects for future developments.
