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8th Edition of the Large Hadron Collider Physics Conference

→ Europe/Paris
Bruno Mansoulie (Université Paris-Saclay (FR)), Giovanni Marchiori (LPNHE Paris), Roberto Salerno (Centre National de la Recherche Scientifique (FR)), Tulika Bose (University of Wisconsin Madison (US))
Description

The Eighth Annual Large Hadron Collider Physics (LHCP2020) conference will be held in Paris fully online from 25th to 30th May 2020

 

NEWS (11/1/2021): the proceedings are now online at https://pos.sissa.it/382 

NEWS (3/6/2020): the instructions for speakers and poster authors for preparing their proceedings have been updated in the proceedings page. The deadline for submitting the proceedings is September 25th, 2020.

NEWS (3/6/2020): we are starting to upload the recordings (with captions) of the sessions to CDS and linking them from the indico timetable

Due to the ongoing COVID-19 pandemic, the original plan of an in-person conference in Paris in May 2020 has been modified as follows.

The Paris edition of LHCP has been delayed by one year and will become LHCP 2021 (7-12 June 2021). 

The LHCP2020 conference will take place fully online in the originally scheduled window of 25 to 30 May 2020. The program is very close to the initial plan.

We appreciate your wish to attend LHCP 2020 and ask for your understanding as we navigate this new path. We very much hope you will be able to join us in Paris next year.

    The LHCP conference series started in 2013 after a successful fusion of two international conferences, "Physics at Large Hadron Collider Conference" and "Hadron Collider Physics Symposium". The conference programme will be devoted to a detailed review of the latest experimental and theoretical results on collider physics, and recent results of the LHC Run II, and discussions on further research directions within the high energy particle physics community including both theory and experiment sides. The main goal of the conference is to provide intense and lively discussions between experimentalists and theorists in research areas such as the Standard Model Physics and Beyond, the Higgs Boson, Supersymmetry, Heavy Quark Physics and Heavy Ion Physics as well as the recent progress in the high luminosity upgrades of the LHC and future colliders developments.

The conference will take place in the International Conference Centre of Sorbonne Université (CICSU) online.

The program of the online conference is close to the original one. The time of the sessions was adjusted to allow people to connect from different regions of the world. The sessions will be recorded and the videos of the presentation will be available for viewing offline after the conference.

REGISTRATION
Thanks to our sponsors (CERN, IUPAP, IN2P3) there are no registration fees. Participants willing to attend the online conference are still requested to register in order to receive by e-mail the instructions for the video connections.

POSTER ABSTRACTS
Abstract submissions with proposals for theory and experimental posters are invited. Please follow the instructions in the Call for poster abstracts.

MAIN DEADLINES
Registration
 
  - opening 14th April 2020 
  - closing 20th May 2020 
Poster abstract submission  
  - submission deadline 7th May 2020
  - acceptance notification 8th May 2020 at the latest

Start of the conference

 25th May 2020 12:30
Proceedings submission 25th September 2020
LHCP2020_collage.pdf
LHCP2020Online_Bulletin.pdf
LHCP2020 stats.pdf
Contact email
Participants
1304 View full list
Webcast
There is a live webcast for this event
Watch
  • Monday 25 May
  • Tuesday 26 May
  • Wednesday 27 May
  • Thursday 28 May
    • Plenary VI: Electroweak Physics
      Conveners: Gautier Hamel de Monchenault (IRFU, CEA, Université Paris-Saclay (FR)), Lucia Di Ciaccio (Centre National de la Recherche Scientifique (FR))
      Recording (without captions)
      Transcript
      Transcript
      Zoom webinar
    • 14:30
      Coffee Break
    • Dark Sectors BSM
      Conveners: Claudia Frugiuele (CERN), Katherine Pachal (Duke University (US)), Ivan Mikulec (Austrian Academy of Sciences (AT)), Carlos Vazquez Sierra (Nikhef National institute for subatomic physics (NL))
      1 - Tuesday webinar
      2 - Thursday webinar
      3 - Friday webinar
      Recording
    • Flavour Physics: CP violation and CKM
      Conveners: Emmanuel Stamou (University of Chicago), Andrea Rossi (Universita e INFN, Padova (IT)), Alex Cerri (University of Sussex (GB)), Lucia Grillo (University of Manchester (GB)), Martino Margoni (Universita e INFN, Padova (IT))
      1 - Tuesday webinar
      2 - Thursday webinar
      3 - Friday webinar
    • Higgs Physics: HH and Decays
      Conveners: Stephen Philip Jones (CERN), Valerio Dao (CERN), Marco Peruzzi (CERN)
      1 - Tuesday webinar
      2 - Thursday webinar
      3 - Friday webinar
    • Heavy Ions: Small systems
      Conveners: Elena Gonzalez Ferreiro (Universidade de Santiago de Compostela (ES)), Alice Ohlson (Lund University (SE)), Iwona Grabowska-Bold (AGH University of Science and Technology (PL)), Camelia Mironov (Massachusetts Inst. of Technology (US)), Yanxi Zhang (CERN)
      1 - Monday webinar
      3 - Thursday recording (without captions)
      3 - Thursday webinar
      • 127
        QGP equilibration in small systems
        Speaker: Dr Aleksas Mazeliauskas (CERN)
        mazeliauskas_LHCP.pdf
        Recording
      • 128
        Recent results on collectivity in small systems from ALICE
        Speaker: Zhanna Khabanova (Nikhef National institute for subatomic physics (NL))
        LHCP2020_Khabanova.pdf
        Recording
      • 129
        Recent results on collectivity in small systems from CMS
        Speaker: Michael Murray (The University of Kansas (US))
        MurrayLHCp.pdf
        Recording
      • 130
        Recent results on collectivity in small systems from ATLAS
        Speaker: James Lawrence Nagle (University of Colorado Boulder)
        nagle_atlas_lhcp2020.pdf
        Recording
    • Outreach
      Conveners: Herbi Dreiner (Bonn University), Sascha Mehlhase (Ludwig Maximilians Universitat (DE)), Michael Hoch (Austrian Academy of Sciences (AT)), Harry Victor Cliff (University of Cambridge (GB))
      1 - Thursday webinar
      2 - Friday webinar
    • QCD Physics
      Conveners: Gudrun Heinrich (Max Planck Institute for Physics), Andreas Morsch (CERN), Bogdan Malaescu (Centre National de la Recherche Scientifique (FR)), Sunil Bansal (Panjab University (IN)), Michael Schmelling (Max-Planck-Gesellschaft (DE)), Emilio Radicioni (Universita e INFN, Bari (IT))
      1 - Tuesday webinar
      3 - Thursday webinar
    • Upgrades & Future: Future Colliders
      Conveners: Jochen Klein (Universita e INFN Torino (IT)), Sarah Marie Demers Konezny (Yale University (US)), Jan Kieseler (CERN), Blake Leverington (Ruprecht Karls Universitaet Heidelberg (DE))
      1 - Monday webinar
      2 - Tuesday webinar
      3 - Thursday webinar
      4 - Friday webinar
    • 16:15
      Coffee Break
    • Plenary VII: BSM-1 (TeV scale)
      Conveners: Patrizia Azzi (INFN Padova (IT)), Pierre Savard (University of Toronto (CA))
      Recording (without captions)
      Transcript
      Transcript
      Webinar
    • Poster Session (I)
      • 146
        $\Upsilon$ production as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}=13$ TeV with ALICE

        In pp collisions at LHC energies, the production of heavy quarks proceeds from the hard scattering and then these quarks hadronise in either open heavy-flavor hadrons or quarkonia (e.g. J/$\psi$, $\psi(2S)$, $\Upsilon$). The study of quarkonium production as a function of charged-particle multiplicity links soft and hard processes and allows to study their interplay. While a linear increase of quarkonium production as a function of charged-particle multiplicity can be reasonably well understood in the context of multi-parton interactions, the observation of deviations with respect to a linear increase requires a more detailed description of the collision and the inclusion of additional mechanisms such as collective effects, color reconnection or percolation.

        In this contribution, we will present the latest ALICE measurements for J/$\psi$ and $\Upsilon$ production as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}=13$ TeV. The self-normalised yield of J/$\psi$ and $\Upsilon$, defined as the ratio between the corresponding $\Upsilon$ yield in a given multiplicity interval to the multiplicity-integrated yield, are measured at forward rapidity (2.5 < y < 4) in the dimuon decay channel. The charged-particle multiplicity is measured in $|\eta|$ <1. We will also perform the first measurement of the double ratios of relative yield of $\Upsilon(2S)$ over $\Upsilon(1S)$ and J/$\psi$ over $\Upsilon(1S)$ as a function of charged-particle multiplicity.

        Speaker: Ms Yanchun Ding ( CCNU (CN), LYON-IP2I(FR))
        PosterLHCP2020_r5.pdf
        Poster video explanation
        Zoom meeting room
      • 147
        A muon tracking algorithm for Level 1 trigger in the CMS barrel muon chambers during HL-LHC

        The electronics of the CMS (Compact Muon Solenoid) DT (Drift Tubes) chambers will need to be replaced for the HL-LHC (High Luminosity Large Hadron Collider) operation due to the increase of occupancy and trigger rates in the detector, which cannot be sustained by present system. A system is being designed that will forward asynchronously the totality of the chambers signals to the control room, at full resolution. A new backend system will be in charge of building the trigger primitives of each chamber out of this asynchronous information, aiming at achieving resolutions comparable to the ones that the offline High Level Trigger can obtain nowadays. In this way, the new system will provide improved functionality with respect to the present one, allowing to improve the resilience against potential aging situations. An algorithm for the trigger primitive generation that will run in this new backend system has been developed and implemented in firmware. The performance of this algorithm has been validated through different methods: from a software emulation approach to hardware implementation tests. A very good performance is achieved, with optimal timing and position resolutions, close to the ultimate performance of the DT chamber system.

        Speaker: Carlos Francisco Erice Cid (Universidad de Oviedo (ES))
        Poster
        Poster video explanation
        Zoom room link
      • 148
        ALICE Measurements of Coherent Rho0 Photoproduction in Pb-Pb Ultra-peripheral Collisions

        The powerful photon fluxes of relativistic nuclei provide the possibility to study photonuclear and two-photon interactions in ultra-peripheral collisions (UPC), where the nuclei do not overlap and no strong nuclear interactions occur. Within the Vector Meson Dominance Model (VDM), the rho0 contribution dominates the QCD part of the photon structure function. The gamma+A → rho0+A process in heavy-ion UPC is an excellent tool to test the black disk regime, where the target nucleus appears like a black disk and the total rho0+A cross section reaches its limit. RHIC and first LHC results have deviated from some Glauber+VDM calculations, which thus call for new data. ALICE reports the first measurements of coherent rho photoproduction accompanied by electromagnetic dissociation (EMD) with data taken at sqrt(s_NN ) =5.02 TeV. The rapidity-dependent cross section
        of coherent rho0 photoproduction is measured and it is compared to theoretical models. In addition, a resonance-like structure around 1.7 GeV/𝑐^2 is observed.

        Speaker: David Horak (Czech Technical University (CZ))
        LHCP_horak.pdf
        Poster Video
        Zoom meeting room
      • 149
        ATLAS LAr Calorimeter Commissioning for LHC Run-3

        Liquid argon (LAr) sampling calorimeters are employed by ATLAS for all electromagnetic calorimetry in the pseudo-rapidity region |η| < 3.2, and for hadronic and forward calorimetry in the region from |η| = 1.5 to |η| = 4.9. In the first LHC run a total luminosity of 27 fb−1 has been collected at center-of-mass energies of 7-8 TeV. After detector consolidation during a long shutdown, Run-2 started in 2015 and about 150fb-1 of data at a center-of-mass energy of 13 TeV was recorded. With the end of Run-2 in 2018 a multi-year shutdown for the Phase-I detector upgrades was begun.
        As part of the Phase-I upgrade, new trigger readout electronics of the ATLAS Liquid-Argon Calorimeter have been developed. Installation began at the start of the LHC shut down in 2019 and is expected to be completed in 2020. A commissioning campaign is underway in order to realise the capabilities of the new, higher granularity and higher precision level-1 trigger hardware in Run-3 data taking. This contribution will give an overview of the new trigger readout commissioning, as well as the preparations for Run-3 detector operation and changes in the monitoring and data quality procedures to cope with the increased pileup.

        Speaker: Sana Ketabchi (University of Toronto (CA))
        LHCP20_ATLAS_LArPoster_v3.pdf
        Poster video explanation
        Zoom meeting room
      • 150
        ATLAS Level-1 Endcap Muon Trigger from Run-2 to Run-3

        The LHC is expected to increase its centre-of-mass energy to 14 TeV and to keep longer time with an instantaneous luminosity of about 2.0×10^34 cm^-2s^-1 for Run-3 scheduled from 2021 to 2024. In order to cope with the high event rate, upgrades of the ATLAS trigger system are required. The level-1 Endcap Muon trigger system identifies muons with high transverse momentum by combining data from a fast muon trigger detector, Thin-Gap Chamber. In the ongoing upgrade in this year, new detectors called the New-Small-Wheel (NSW) and RPC-BIS78, will be installed in the inner station region for the endcap muon trigger. Finer track information from the NSW and RPC-BIS78 can be used as part of the muon trigger logic to enhance performance significantly. In order to handle data from both TGC and NSW, some new electronics have been developed, including the trigger processor board known as Sector Logic (SL). The SL board has a modern FPGA to make use of Multi-Gigabit transceiver technology, which will be used to receive data from the NSW. Increasing of the FPGA resource also makes to improve the momentum resolution and additional information, such as charge identification. This presentation describes the aforementioned upgrades of the level-1 Endcap Muon trigger system. Particular emphasis will be placed on the new algorithm in Sector Logic and the current status of installation and commissioning. The expected trigger performance by the new algorithm will also be discussed.

        Speaker: Takuya Nobe (University of Tokyo (JP))
        Poster
        Poster video explanation
        Zoom meeting room
      • 151
        ATLAS Open Data: Data visualisation and educational physics analysis to re-discover the Higgs

        Modern particle physics analysis is carried out using sophisticated programming and coding. How, therefore, can we genuinely introduce students to experimental particle physics analysis without an initial exposure to the coding behind? The answer from ATLAS Open Data is to build tools for interactive data visualisation. Web-based resources such as the “Histogram Analyser”, “ATLAS detector visualisation”, “Interactive physics paper” and “Analysis Browser” are easy to use, but still very powerful. Students already intrigued by the physics can then build up to a coding analysis by running Jupyter notebooks out-of-the-box. Such notebooks invite them to read some short pieces of code, but without asking them to write any, just yet. With the use of these tools and documentation, students can be guided to find the Higgs boson with only their mouse!

        Speaker: Meirin Oan Evans (University of Sussex (GB))
        Captions.srt
        Poster
        Poster video explanation
        Zoom meeting room
      • 152
        ATLAS public engagement: The CERN Open Days experience

        The ATLAS experiment at the Large Hadron Collider is collecting unprecedented amounts of proton–proton collision data. The ATLAS Collaboration analyses these data, seeking to give answers to questions that have puzzled particle physicists for many decades now. In this process, the Standard Model is being precisely measured and searches for new physics are performed in sophisticated and clever data analyses. When ATLAS physicists explain to non-experts what they are doing and why, they use their passion to come up with equally clever means to achieve that. Their aim is both to motivate the younger generations as potential future scientists, and to reach out to the general public, creating an audience more interested in future achievements and convincing them of the importance of their pursuits. While there are many opportunities for interacting with the public, events like the CERN Open Days in 2019, with about 70000 visitors, carry a special weight in terms of potential impact. This contribution will highlight activities the ATLAS Collaboration used to connect with the visitors during the 2019 CERN Open Days. It will discuss the experience of the event preparation and will conclude with impressions of the impact of the proposed activities to the interactions with the amazing visitors, which made the 2019 CERN Open Days weekend a memorable event.

        Speaker: Ana Peixoto (LIP Laboratorio de Instrumentacao e Fisica Experimental de Part)
        Poster
        Poster video explanation
        Poster video explanation
        Zoom meeting room
      • 153
        ATLAS Virtual Visits – Take part from anywhere in the world

        The Virtual Visit service run by the ATLAS Collaboration has been provided since 2010. The ATLAS Collaboration has used this popular and effective method to bring the excitement of scientific exploration and discovery into classrooms and other public places around the world. The programme, which uses a combination of video conferencing, webcasts, and video recording to communicate with remote audiences has already reached tens of thousands of viewers, with a large number of languages, from tens of countries covering the six populated continents.
        We present a summary of the ATLAS Virtual Visit service that is currently in use: the booking system, the video conference that is held from the ATLAS Visit Centre and ATLAS Control Room, the possibility to make virtual tours from the ATLAS cavern, and the new system that is being installed in the ATLAS cavern to provide high-quality underground virtual visits. In addition, we show the reach of the programme over the last few years.

        Speaker: Muhammad Alhroob (University of Oklahoma (US))
        Poster
        Poster video explanation
        Zoom meeting room
      • 154
        Beam-test evaluation of the precision timing capabilities of a CMS HGCAL prototype

        The existing CMS endcap calorimeters will be replaced with a High Granularity Calorimeter (HGCAL) for operation at the High-Luminosity (HL) LHC. Radiation hardness and excellent physics performance will be achieved by utilising silicon pad sensors and SiPM-on-scintillator tiles with high transverse and longitudinal segmentation. One of the major challenges of the HL-LHC will be the high pileup environment, with interaction vertices spread not only in position, but also in time. In order to efficiently reject particles originating from pileup, precision timing information of the order of 30 ps will be of great benefit. In order to meet such performance goals, the HGCAL will provide timing measurements for individual hits with signals above 12 fC (equivalent to 3-10 MIPs), such that clusters resulting from particles with pT > 5 GeV should have a timing resolution better than 30ps.

        In order to assess the technical feasibility and physics performance of such a design, beam tests were performed with a prototype of HGCAL silicon modules at the CERN SPS. We present the detector and DAQ components related to the precision timing evaluation, as well as calibration techniques and preliminary results on the timing performance.

        Speaker: Mr Axel Buchot Perraguin (Centre National de la Recherche Scientifique (FR))
        LHCP2020_HGCAL_TIMING_AXEL_BUCHOT.pdf
        Poster video explanation
        Zoom meeting room
      • 155
        Calibration of the luminosity measurement with the Van der Meer method in proton-proton collisions at the CMS experiment

        The luminosity measurement of the CMS experiment is calibrated under special beam conditions with beam separation scans called Van der Meer (VdM) scans. In a VdM scan, the two proton beams are separated transversely and moved in steps across each other. From the rate measurement of a luminosity detector as function of the transverse beam separation, the absolute luminosity scale is inferred and used to determine a calibration constant. The beam separation scale is calibrated with special length scale scans, and time-dependent variations are corrected for from measurements of beam position monitors. The rate measurement is normalized with the measured bunch currents. Electromagnetic interactions between the proton beams influence both the separation scale and the rate measurement. A bias occurs in the calibration procedure due to the assumption of factorizable bunch densities, and is corrected for using a reconstruction of the transverse bunch shapes from special beam-imaging scans.

        Speaker: Joscha Knolle (Deutsches Elektronen-Synchrotron (DE))
        JK_200528_luminositycalibrationcms_v2.pdf
        Video explanation
        Zoom meeting room
      • 156
        Collider probes of real triplet scalar dark matter

        We study discovery prospects for a real triplet extension of the Standard Model scalar sector at the Large Hadron Collider (LHC) and a possible future 100TeV $pp$ collider. We focus on the scenario in which the neutral triplet scalar is stable and contributes to the dark matter relic density. When produced in $pp$ collisions, the charged triplet scalar decays to the neutral component plus a soft pion or soft lepton pair, yielding a disappearing charged track in the detector. We recast current 13TeV LHC searches for disappearing tracks, and find that the LHC presently excludes a real triplet scalar lighter than 287GeV with $\mathcal{L}=\rm36$fb$^{-1}$. The reach will extend to 608GeV and 761GeV with the collection of $\mathcal{L}=300$fb$^{-1}$ and $3000$fb$^{-1}$ respectively. We extrapolate the 13TeV analysis to a prospective 100TeV $pp$ collider, and find that a $\sim3$TeV triplet scalar could be discoverable with $\mathcal{L}=30$ ab$^{-1}$, depending on the degree to which pile up effects are under control. We also investigate the dark matter candidate in our model and corresponding present and prospective constraints from dark matter direct detection. We find that currently XENON1T can exclude a real triplet dark matter lighter than $\sim3$TeV for a Higgs portal coupling of order one or larger, and the future XENON20T will cover almost the entire dark matter viable parameter space except for vanishingly small portal coupling.

        Speaker: Yong Du (University of Massachusetts-Amherst)
        LHCP-poster-Yong Du.pdf
        Our paper for this poster
        Poster video explanation
        Zoom meeting room
      • 157
        Development of the ATLAS Liquid Argon Calorimeter Readout Electronics for the HL-LHC

        To meet new TDAQ buffering requirements and withstand the high expected radiation doses at the high-luminosity LHC, the ATLAS Liquid Argon Calorimeter readout electronics will be upgraded. The triangular calorimeter signals are amplified and shaped by analogue electronics over a dynamic range of 16 bits, with low noise and excellent linearity. Developments of low-power preamplifiers and shapers to meet these requirements are ongoing in 130nm CMOS technology. In order to digitise the analogue signals on two gains after shaping, a radiation-hard, low-power 40 MHz 14-bit ADCs is developed using a pipeline+SAR architecture in 65 nm CMOS. Characterization of the prototypes of the frontend components show good promise to fulfill all the requirements. The signals will be sent at 40 MHz to the off-detector electronics, where FPGAs connected through high-speed links will perform energy and time reconstruction through the application of corrections and digital filtering. Reduced data are sent with low latency to the first level trigger, while the full data are buffered until the reception of trigger accept signals. The data-processing, control and timing functions will be realized by dedicated boards connected through ATCA crates. Results of tests of prototypes of front-end components will be presented, along with design studies on the performance of the off-detector readout system.

        Speaker: Devanshu Kiran Panchal (University of Texas at Austin (US))
        LHCP2020_Poster_dpanchal_.pdf
        Poster Talk
        Zoom Meeting Room
      • 158
        Energy dependence of light neutral mesons $p_{\rm T}$ spectrum produced in pp collisions at the LHC measured with ALICE

        We present in this poster the measurement of light neutral mesons, $\pi^{0}$ and $\eta$, in pp collisions at different center-of-mass energies obtained with the ALICE experiment at CERN. In pp collisions, neutral mesons are used to validate the pQCD predictions and also act as a baseline for their measurement in heavy-ion collisions. Neutral mesons have been reconstructed by invariant mass analysis of two decay photons using ALICE calorimeters EMCal and PHOS, in the transverse momentum range 0.8 $< p_{\rm T} <$ 40 GeV$/c$. In addition, neutral mesons via conversion photons method are measured up to very low $p_{\rm T}$ ($\sim$ 0.35 GeV$/c$) using the central tracking system in ALICE.
        Results from different techniques are combined to provide precision measurements of $\pi^{0}$ and $\eta$ in pp collisions over much wider $p_{\rm T}$ range than any other identified hadrons $p_{\rm T}$ spectra which are used for tuning QCD parameters.
        We will show the invariant cross-sections, $m_{\rm T}$-scaling and $x_{\rm T}$-scaling for $\pi^{0}$ and $\eta$.

        Speaker: Ms Pooja Pareek (Variable Energy Cyclotron Centre (IN))
        LHCP2020_Poster_Pooja Pareek.pdf
        Poster video explanation
        Poster video explanation cernbox
        Zoom meeting room
      • 159
        Exploring the lifetime frontier with the proposed MATHUSLA detector

        MATHUSLA is a proposed detector that will be placed above the CMS experiment to study long-lived particles (LLP) produced by the LHC. It is instrumented with a tracking system to observe LLP decays inside its empty volume, and it is composed of a modular array of detectors covering together (100 × 100) m2 × 25 m high. MATHUSLA, with a large detection area and good granularity tracking system, is also an efficient cosmic-ray telescope to study EAS.
        To study the main expected sources of background in the MATHUSLA detector, a test stand was built on the surface above the ATLAS detector, taking data during 2018.
        In this poster we will describe the main detector concept, layout and current status as well as the test stand resutls. These provided measurements of the flux of cosmic rays in the surface above ATLAS and the rate of muons from the LHC interactions reaching the surface.

        Speaker: Emma Torro Pastor (Univ. of Valencia and CSIC (ES))
        LHCP2020_Mathusla_poster.pdf
        Poster video explanation
        Zoom meeting room
      • 160
        Formalism of hydrodynamics with spin degrees of freedom.

        Measurements made recently by the STAR collaboration show that the Lambda hyperons produced in relativistic heavy-ion collisions are subject to global spin polarization with respect to an axis coincident with the axis of rotation of the produced matter. Recently formulated formalism of relativistic hydrodynamics with spin, which is a generalization of the standard hydrodynamics, is a natural tool for describing the evolution of such systems. This approach is based on the conservation laws and the form of the energy-momentum tensor and spin tensor postulated by de Groot, van Leeuwen, and van Weert (GLW). Using Bjorken symmetry we show how this formalism may be used to determine observables describing the polarization of particles measured in the experiment.

        Speaker: Mr Rajeev Singh (Institute of Nuclear Physics Polish Academy of Sciences)
        Paper on which poster is based.
        Slides_with_more_details_Rajeev_Singh.pdf
        Theory_Poster_Rajeev_Singh.pdf
        Video_Rajeev_Singh.mp4
        Zoom meeting room
      • 161
        Full Run 2 ATLAS Transverse Missing Momentum Trigger Performance

        Transverse missing momentum from non-interacting particles is one of the important characteristics for many analyses especially for Beyond Standard Model physics searches. To study these events at the Large Hadron Collider (LHC) with the ATLAS experiment an efficient trigger selection is needed. The ATLAS transverse missing momentum trigger uses calorimeter-based global energy sums together with specifically developed pile-up mitigation techniques. The high number of pile-up interactions was one of the major challenges faced during Run 2 and a continuous effort was needed to improve the pile-up rejection and to keep the trigger rate reasonable. This poster presents the techniques used to improve the Run 2 transverse missing momentum trigger performance, the full Run 2 performance and an outlook on possible improvements using tracking for Run 3.

        Speaker: Jonas Wurzinger (University of Oxford (GB))
        METPerf_LHCP_2020_poster_JonasWuerzinger.pdf
        Poster Pitch Video
        Zoom meeting room
      • 162
        HPS@L1 algorithm for the upgraded CMS level-1 hadronic tau trigger for the HL-LHC

        The High-Luminosity LHC will open an unprecedented window on the weak-scale nature of the universe, providing high-precision measurements of the Standard Model as well as searches for new physics beyond the standard model. The Compact Muon Solenoid (CMS) experiment is planning to replace entirely its trigger and data acquisition system to achieve this ambitious physics program. Efficiently collecting those datasets will be a challenging task, given the harsh environment of 200 proton-proton interactions per LHC bunch crossing. The new Level-1 trigger architecture for the HL-LHC will improve performance with respect to Phase I through the addition of tracking information and updates of the trigger electronics, which will allow to run a simplified particle-flow (PF) event reconstruction on the first trigger level (L1).
        In this poster, we present the development of an algorithm to select events containing hadronic tau decays on L1 during LHC Phase II. The algorithm is inspired by the “hadrons-plus-strips” (HPS) algorithm, which has been used for the reconstruction of hadronic taus in offline analyses performed by CMS during LHC Runs 1 and 2. It takes advantage of the capability of the upgraded trigger to perform tracking and PF event reconstruction on L1 and is referred to as the HPS@L1 algorithm. The performance of the algorithm is studied in terms of efficiency and rate expected for a single hadronic tau and for a tau pair (ditau) trigger, using simulated events. For a tau isolation selection that yields a plateau efficiency of 85% per tau, the algorithm achieves a tau pT threshold of about 20 GeV for the ditau trigger, which is lower than the pT threshold achieved by the ditau trigger used by CMS during LHC Phase I.

        Speaker: Dr Sandeep Bhowmik (National Institute of Chemical Physics and Biophysics (EE))
        Poster video explanation
        Sandeep_HPS_LHCP_20200526_v3.pdf
        Zoom meeting room
      • 163
        Learning Physics at Future $e^-e^+$ Colliders with Machine

        Information deformation and loss in jet clustering are one of the major limitations for precisely measuring hadronic events at future $e^-e^+$ colliders. Because of their dominance in data, the measurements of such events are crucial for advancing the precision frontier of Higgs and electroweak physics in the next decades. We show that this difficulty can be well-addressed by synergizing the event-level information into the data analysis, with the techniques of deep neutral network. In relation to this, we introduce a CMB-like observable scheme, where the event-level kinematics is encoded as the Fox-Wolfram (FW) moments at leading order and multi-spectra at higher orders. Then we develop a series of jet-level (w/ and w/o the FW moments) and event-level classifiers, and analyze their sensitivity performance comparatively with two-jet and four-jet events. As an application, we analyze measuring Higgs decay width at $e^-e^+$ colliders with the data of 5ab$^{-1}@$240GeV. The precision obtained is significantly better than the baseline ones presented in documents. We expect this strategy to be applied to many other hadronic-event measurements at future $e^-e^+$ colliders, and to open a new angle for evaluating their physics capability.

        Speaker: LINGFENG LI (HKUST)
        Jet or Event.pdf
        Jet_or_event:Video
        Zoom meeting room
      • 164
        Light (anti)nuclei production in high-energy nuclear collisions at the LHC with ALICE.

        The measurement of (anti)nuclei production in pp, p-A and A-A collisions at the ultrarelativistic energies of LHC is important to understand hadronization. The excellent tracking and particle identification capabilities of ALICE make it the most suited detector at the LHC to study light (anti)nuclei produced in high-energy hadronic collisions. (Anti)nuclei with mass numbers up to 4, such as (anti)deuterons, (anti)tritons, (anti)$^3$He and (anti)$^4$He have been successfully identified in ALICE at mid rapidity $|\eta|<$0.9.
        In this poster, multiplicity dependent results on the yields, transverse momentum distributions and the antinuclei/nuclei ratios will be presented and compared with the expectations of coalescence and statistical hadronization models to provide insight into their production mechanism in heavy-ion collisions.

        Speaker: Chiara Pinto (INFN and University of Catania)
        LightNuclei_ALICE_poster.pdf
        PosterExplanation_LightNuclei.mp4
        Zoom Meeting Room
      • 165
        Measurement of the combined online and offline b-jet identification efficiency with ttbar events using a likelihood method in the ATLAS detector

        The identification of jets coming from the hadronization of b-quarks (b-tagging) is instrumental for many physics analyses performed at the Large Hadron Collider. ATLAS has b-tagging capability starting at trigger level, where b-tagging algorithms are fed with tracks that are reconstructed at the High-Level Trigger stage. Physics analyses with b-jets in the final state, but no lepton or missing transverse energy, benefit from using b-jet identification at trigger level in order to improve the signal efficiency. In Run 2, b-jet trigger efficiency is measured using a data sample enriched in ttbar di-leptonic events, employing a likelihood method. The b-tagging efficiency, for trigger algorithms as well as for the combination between trigger and offline algorithms, is extracted for jets in a transverse momentum range from 35 to 600 GeV, and data-to-simulation scale factors are derived.

        Speaker: Giovanni Bartolini (CPPM, Aix-Marseille Université, CNRS/IN2P3 (FR))
        GBposterLHCP20.pdf
        Poster_video_explanation.mp4
        Zoom meeting room
      • 166
        Measurement of the Standard Model Higgs boson produced in association with a vector boson and decaying to a pair of b-quarks in p-p collisions at 13 TeV using the ATLAS detector

        The Higgs boson decays to pairs of b-quarks were studied in associated production with a W or Z boson by the ATLAS Collaboration. The decay to b-quarks is of particular importance since it allows a direct measurement of the coupling of the Higgs boson to b-quarks. The highest sensitivity in this channel is obtained when the vector boson produced alongside the Higgs boson decays to leptons. The analysed data were collected in proton-proton collisions at the Large Hadron Collider during Run 2 at a center-of-mass energy of 13 TeV. The final state requires having exactly 2 b-tagged jets and either 0, 1 or 2 charged leptons (electrons or muons, denoted as ‘l’) corresponding to the following channels: Z → vv , W → lv and Z →ll. In this poster a review of the analysis and the results from the Higgs signal measurement will be shown.

        Speaker: Konie Al Khoury (Université Paris-Saclay (FR))
        LHCP_Poster_VHbb_Measurement.pdf
        Video explanation
        Zoom meeting room
      • 167
        Modified Lepton Couplings and the Cabibbo-Angle Anomaly

        Recently, discrepancies of up to 4σ between the different determinations of the CKM element Vus have been observed. Modified neutrino couplings to Standard Model gauge bosons could explain this "Cabibbo-angle anomaly". However, this explanation necessarily affects also the EW fit and the other observables sensitive to LFU violation. Therefore, in order to assess the viability, a global fit of all experimental data is required. This poster provides an overview of the anomaly and shows the result of the model-independent global analysis. We find that modifications of lepton couplings significantly reduce the tensions in the Cabibbo angle and improve at the same time the agreement with the other data, resulting in an excellent fit.

        Speaker: Mr Claudio Andrea Manzari (University of Zurich)
        Poster.pdf
        Poster Video Explanation
        Zoom Link Room
      • 168
        Observation of constrained MSSM with the aid of advanced statistical technique.

        The discovery of a 125 GeV Higgs-boson at the Large Hadron Collider poses a significant challenge for the minimal supersymmetric standard model (MSSM). We present our phenomenological research on various Higgs allied processes in the light of the pre-existing data from several other experiments including the data on electroweak precision observables, B-physics and the data from dark matter searches to investigate finely tuned CMSSM using Bayesian inference technique which is also compared with other advanced statistical techniques to restrict the SUSY parameter space.

        Speaker: Ms SURABHI GUPTA (Aligarh Muslim University)
        LHCPposter_SurabhiGupta.pdf
        Poster video explanation
        Zoom meeting room
      • 169
        Optimisation of the ATLAS Deep Learning Flavour Tagging Algorithm

        The identification of heavy flavour jets (tagging) plays an important role in many
        physics analyses at the ATLAS experiment. It is an essential tool for precision measurements as well as for searches for new physics phenomena. Significant progress has been made in the last few years to ensure the robust training of deep neural networks, requiring large training datasets.
        The ATLAS deep learning tagger framework (DL1) uses deep neural networks based onTensorFlow and Keras to distinguish b-, c-, and light-flavour jets using inputs from ATLAS's low-level b-taggers. The latest optimisation of the DL1 tagger on Particle Flow jets and Variable-Radius Track jets shows substantial improvement with respect to the previously available taggers. An introduction to the DL1 framework, the training procedure, as well as the resulting performance improvements will be shown.

        Speaker: Manuel Guth (Albert Ludwigs Universitaet Freiburg (DE))
        LHCP-DL1_Manuel-Guth.pdf
        Poster video explanation
        Zoom meeting room
      • 170
        Performance studies of the Run 3 jFEX algorithms in the ATLAS calorimeter trigger

        The Run 2 ATLAS trigger system is comprised of two levels: a hardware level (L1) and a software higher level trigger (HLT). Between late 2018 and early 2021, the ATLAS trigger system is undergoing upgrades. Two major sets of upgrades to the ATLAS level 1 trigger system will be the increase in read-out granularity in the LAr detectors ("supercells") and the addition of new Feature EXtractors (FEXs): Jet FEX (jFEX), global FEX (gFEX), and electromagnetic FEX (eFEX). The jFEX identifies jets and calculates missing transverse momentum and other energy sums. The gFEX identifies large radius jets. The new Run 3 L1 jets will make use of the improved resolution and the added algorithm flexibility provided by these upgrades. The incorporation of the jFEX and gFEX in Run 3 will cause L1 jet triggers to change significantly. To maintain the efficiency of the HLT and L1 jet chains and to maximize use of L1 rate, it is crucial that the performance of Run 3 L1 jet triggers is optimized. Jet triggers for low-threshold multijet triggers and for trigger-level analyses will benefit from polished Run 3 L1 jets. Studying the performance of Run 2 L1 jets allows for the determination of areas of improvement for Run 3 L1 jet triggers. Presented are trigger efficiencies for Run 2 L1 jets for various years, as well as the expected trigger performance for Run 3 L1 jets. Performance studies are also included for the jFEX MET algorithm.

        Speaker: Elena Michelle Villhauer (The University of Edinburgh (GB))
        LHCP_2020_Villhauer.pdf
        poster_video_explanation.mp4
        Zoom meeting room
      • 171
        Precise luminosity determination at CMS

        Precise luminosity calibration at bunched-beam hadron colliders like the Large Hadron Collider (LHC) is critical to determine fundamental parameters of the standard model and to constrain or to discover beyond-the-standard-model phenomena. The luminosity determination at the LHC interaction point 5 with the Compact Muon Solenoid (CMS) detector, using proton-proton, proton-nucleus, or nucleus-nucleus collisions during Run 2 of the LHC (2015–2018), is reported. The absolute luminosity scale is obtained using beam-separation (“van der Meer”) scans performed with special beam optics, large-emittance beams, and fewer, well-separated bunches to reduce potential systematic effects. The sources of systematic uncertainty are given. The contribution to the total uncertainty in the integrated luminosity after applying the van der Meer calibration to the entire data-taking period is discussed, considering the information from short “emittance” scans performed regularly in CMS since 2017.

        Speaker: Mahmoud Gadallah (Eotvos Lorand University (HU))
        lhcp2020_poster.pdf
        Poster video explanation
        Zoom meeting room
      • 172
        Probe pT-dependent flow vector fluctuations with ALICE

        Emil Gorm Nielsen (on behalf of the ALICE Collaboration)
        Niels Bohr Institute, University of Copenhagen, Denmark

        One of the main goals of ultra-relativistic nuclear collisions is to create a
        new state of matter called quark-gluon plasma (QGP) and study its properties. One of the experimental observables is the anisotropic flow vn, defined
        as correlation of azimuthal angle of each particle with respect to a common
        symmetry plane Ψn. The vn and Ψn represent the magnitude and the phase
        of a complex flow vector Vn, respectively. Azimuthal anisotropies are traditionally measured using 2- and/or multi-particle correlations over a large
        range in pT and eta. However, hydrodynamic calculations show that the
        event-by-event fluctuations in the initial conditions and the dynamics during
        the system expansion lead to flow vector fluctuation in pT and/or η (also
        called de-correlations of flow vector), including flow magnitude and flow angle fluctuations.
        In this poster, we present the evidence of pT-dependent flow vector fluctuations in Pb–Pb collisions at √sNN = 5.02 TeV, using both vn{2}/vn[2]
        and rn observables. In addition, newly proposed four-particle correlations
        are used to study the contributions of flow magnitude and flow angle fluctuations separately. Considering that the size of flow vector fluctuations is
        sensitive to both initial conditions and the properties of the created QGP,
        these measurements will help us better constrain hydrodynamic models.

        Speaker: Emil Gorm Nielsen (University of Copenhagen (DK))
        LHCP2020_poster.pdf
        poster video explanation
        Zoom meeting room
      • 173
        Probing $Zt\bar{t}$ couplings using $Z$ boson polarization in $ZZ$ production at hadron colliders

        We propose to utilize the polarization information of the $Z$ bosons in $ZZ$ production, via the gluon-gluon fusion process $gg\to ZZ$, to probe the $Zt\bar{t}$ gauge coupling. The contribution of longitudinally polarized $Z$ bosons is sensitive to the axial-vector component ($a_t$) of the $Zt\bar{t}$ coupling. We demonstrate that the angular distribution of the charged lepton from $Z$ boson decays serves well for measuring the polarization of $Z$ bosons and the determination of $a_t$. We show that $ZZ$ production via the $gg\to ZZ$ process complement to $Zt\bar{t}$ and $tZj$ productions in measuring the $Zt\bar{t}$ coupling at hadron colliders.

        Speaker: Dr Bin Yan (Los Alamos National Laboratory)
        ggvv_poster_BY.pdf
        poster_video.mp4
        zoom meeting room
      • 174
        Projected ATLAS Electron and Photon Trigger Performance in Run 3

        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. During Run 3 (2021-2024) main triggers used for those physics studies will be a single-electron trigger with ET threshold around 25 GeV and a diphoton trigger with thresholds at 25 and 35 GeV. Relying on those simple, general-purpose triggers is a robust trigger strategy, tested already in Run 2 (2015-2018), at a cost of slightly higher trigger output rates, than to use a large number of analysis-specific triggers. In preparation for Run 3 data-taking, the ATLAS detector is undergoing an upgrade of the first, hardware, level of the calorimeter trigger and trigger software is being migrated to the multi-threaded framework AthenaMT. Impact from these modifications on the electron and photon triggers as well as their projected performance in Run 3 is presented.

        Speaker: Gonzalo Enrique Orellana (National University of La Plata (AR))
        OrellanaG-LHCP2020.pdf
        Poster video explanation
        Zoom meeting room
      • 175
        Sbottoms as probes to MSSM with nonholomorphic soft interactions

        Presence of non-holomorphic soft SUSY breaking terms is known to be a possibility in the popular setup of the Minimal Supersymmetric Standard Model (MSSM). It has been shown that such a scenario known as Non-Holomorphic Supersymmetric Standard Model (NHSSM) could remain ‘natural’ (i.e., not fine-tuned) even in the presence of a rather heavy higgsino-like LSP. In a first study of such a scenario at colliders (LHC), we explore a possible way that focuses on the sbottom phenomenology. This exploits the usual tanβ-dependence (enhancement) of the bottom Yukawa coupling but reinforced/altered in the presence of non-vanishing nonholomorphic soft trilinear parameter A'_b. For a given set of masses of the sbottom(s) and the light electroweakinos (LSP, lighter chargino etc.) which are known from experiments, the NHSSM could manifest itself via event rate in the 2b + MET final state, which could be characteristically different from its MSSM expectation. Impact on the phenomenology of the stops at the LHC is also touched upon.

        Speaker: Ms Samadrita Mukherjee (Indian Association for the Cultivation of Science)
        Poster Audio-Sbottom as probes to MSSM with Non-Holomorphic Soft Interactions
        Samadrita-LHCP2020-Poster.pdf
        Zoom Meeting Room - Meeting ID: 915 5627 6718
      • 176
        Search for heavy diboson resonances in semi-leptonic final states in pp collisions at sqrt{s} = 13 TeV with the ATLAS detector

        A search for heavy resonances decaying into WW, Z Z or W Z using proton–proton collision data at a centre-of-mass energy of √ s = 13 TeV. The data, corresponding to an integrated luminosity of 139 fb−1 , were recorded with the ATLAS detector from 2015 to 2018 at the Large Hadron Collider. The search is performed for final states in which one W or Z boson decays leptonically, and the other W boson or Z boson decays hadronically. The data are found to be described well by expected
        backgrounds. Upper bounds on the production cross sections of heavy resonances are derived in the mass range 300–5000 GeV within the context of Standard Model extensions with a neutral scalar, a heavy vector triplet or warped extra dimensions. Production through gluon–gluon fusion, Drell–Yan or vector-boson fusion are considered, depending on the assumed model.

        Speaker: Mr Zhongyukun Xu (Shandong University (CN))
        Poster video explanation
        Search_for_heavy_diboson_resonances_in_semi-leptonic_final_states_in_pp_collisions_at_s13_TeV_with_the_ATLAS_detector_.pdf
        Zoom meeting room
      • 177
        Search for phenomena beyond the Standard Model in events with large b-jet multiplicity using the ATLAS detector at the LHC

        Events with a large number of high-pT b-jets are rare in the Standard Model (SM); an excess of events with such topology would be a signal of phenomena beyond the SM. One phenomenon where a large excess is expected is a variant of supersymmetry in which R-parity is violated, allowing baryon number violating decays of the super partners of the SM particles.

        This analysis presents the search for physics beyond the SM in events with at least eight jets and at least six b-jets. It was performed using Run 2 data collected by ATLAS detector corresponding to an integrated luminosity of 139 fb-1 of pp collisions at a center-of-mass energy of 13 TeV. We consider specifically the production of a pair of heavy scalar top quarks which decay to a b-quark and a chargino, which in turn decays into bbs quarks via a virtual stop.

        The most dominant source of background is multijet production, which is estimated using a data-driven technique called the Tag-Rate-Function multijet method, which is based on theprobability of identifying jets from $b$-quarks. This method is extensively validated using data and MC simulation. The analysis strategy is based on counting the number of events with high jet and b-tagged jet multiplicities, which are categorized into eight analysis regions. A fit is performed to estimate the expected sensitivity of the signal strength. Expected and observed 95% CL upper limits are set based on the stop and chargino masses.

        Speaker: Hoang Dai Nghia Nguyen (CPPM, Aix-Marseille Université, CNRS/IN2P3 (FR))
        LHCP_poster_Nghia.pdf
        Poster video explanation
        Zoom meeting room
      • 178
        Search for supersymmetry with photons

        Most recent results on searches for supersymmetric (SUSY) particles decaying to final states containing high energy photon(s) are presented. The searches are based on data collected at the center-of-mass energy of 13 TeV in proton-proton collisions recorded by the CMS detector.

        Speaker: Krisztian Farkas (Eotvos Lorand University (HU))
        Poster video explanation
        Search_for_supersymmetry_with_photons.pdf
        Zoom meeting room
      • 179
        Searches for dark photon with the ATLAS detector at the LHC

        Many extensions to the Standard Model introduce a hidden or dark
        sector to provide candidates for dark matter in the universe an
        explanation to astrophysical observations such as the positron excess
        observed in the cosmic radiation flux. this hidden sector could rise
        from an additional U(1)d gauge symmetry. The gauge boson of the dark
        sector would be either a massless or a massive dark photon that can
        either kinetically mix with the SM photon, or couple to the Higgs
        sector via some mediators. If dark photons decay back to the SM with a
        significant branching ratio, we could either observe measurable
        deviations in some particular Higgs decay channels or new exotic
        signatures that would be accessible at LHC energies. We will present a
        brief overview of searches of dark photon signals with the ATLAS
        detector, with a particular emphasis on some SM Higgs decay channels.

        Speaker: Hassnae El Jarrari (Universite Mohammed V (MA))
        Poster_LHCP2020.pdf
        Poster video explanation
        Zoom meeting room
      • 180
        Small-Strip Thin Gap Chambers for the Muon Spectrometer Upgrade of the ATLAS Experiment

        The instantaneous luminosity of the Large Hadron Collider at CERN will be increased by about a factor of five with respect to the design value by undergoing an extensive upgrade program over the coming decade. The largest phase-1 upgrade project for the ATLAS Muon System is the replacement of the present first station in the forward regions with the New Small Wheels (NSWs) during the long-LHC shutdown in 2019-2021.
        Along with Micromegas, the NSWs will be equipped with eight layers of small-strip thin gap chambers (sTGC) arranged in multilayers of two quadruplets, for a total active surface of more than 2500 m$^2$. To retain the good precision tracking and trigger capabilities in the high background environment of the high luminosity LHC, each sTGC plane must achieve a spatial resolution better than 100 μm to allow the Level-1 trigger track segments to be reconstructed with an angular resolution of approximately 1mrad. The basic sTGC structure consists of a grid of gold-plated tungsten wires sandwiched between two resistive cathode planes at a small distance from the wire plane. The precision cathode plane has strips with a 3.2mm pitch for precision readout and the cathode plane on the other side has pads for triggering. The sTGC design, performance, construction and integration status will be discussed, along with results from tests of the chambers with nearly final electronics with beams, cosmic rays and high-intensity radiation sources.

        Speaker: Auriane Canesse (McGill University, (CA))
        Poster_ATLAS_sTGC.pdf
        Poster video explanation
        Zoom meeting room
      • 181
        Study of top-quark decay process and new limits on Wtb anomalous couplings.

        We study new physics contributions to Wtb anomalous couplings in top-quark decay process t-> Wb at the partonic level. In particular, we compute the limits on anomalous couplings to Wtb vertex. Limits were obtained at 13 TeV LHC energy with an integrated luminosity of 36.1 fb^-1 and predictions for future circular colliders, namely, HL-LHC, HE-LHC and FCC-hh were given. For future colliders, the projected luminosities of 0.3 to 3 ab^-1 at HL-LHC, 3 to 12 ab^-1 at HE-LHC, and 10 to 30 ab^-1 at FCC-hh were explored. We also analyze the CP-violation sensitivity for the process t-> Wb and found that the future colliders with enhanced luminosities give more promising results.

        Speaker: Ms Apurba Tiwari (Aligarh Muslim University)
        Apurba_recording_lhcp2020.mp4
        Poster
        Zoom meeting room
      • 182
        The ATLAS Hardware Track Trigger performance studies for the HL-LHC

        For the High-Luminosity LHC, planned to start in 2027, the ATLAS experiment will be equipped with the Hardware Tracking for the Trigger (HTT) system, a dedicated hardware system able to reconstruct tracks in the silicon detectors with short latency. The evolved TDAQ system design consists of a two-level hardware trigger in which the HTT is used in a low-latency mode (L1Track), providing tracks in regions of ATLAS at a rate of up to 4 MHz, with a latency of a few tens of micro-seconds. Different readout scenarios for the silicon pixel layers of the inner detector at 4 MHz are under study. While the full, bit-level simulation of the HTT is under development, a fast simulation was produced using parametrized track resolutions, to study the impact of L1Track reconstruction on physics benchmark channels. In this paper we describe the status of the ongoing HTT performance studies for the HL-LHC trigger menu, covering the impact on b-tagging and on muti-jets and leptonic signatures.

        Speaker: Ana Luisa Carvalho (LIP (PT))
        Overview
        posterHTT_LHCP2020.pdf
        Zoom meeting room
      • 183
        The ATLAS Inner Detector Trigger performance in pp collisions at 13 TeV during LHC Run 2

        The Inner Detector (ID) trigger plays an essential role in the ATLAS trigger system, enabling the high purity reconstruction of physics objects - electron, tau, muon, bjet candidates, providing access to regions of the phase space populated by these objects which span a wide range of kinematic regimes. These are essential for the core physics programme at ATLAS: Standard Model measurements; Flavour physics; and Beyond the Standard Model searches. Having highly efficient tracking trigger algorithms is therefore essential to pursue the ATLAS physics goals, both in the Run-2 analyses and for the preparations for Run-3. Here, the design and performance of the ATLAS ID trigger used at the LHC during the full Run-2 data taking period is discussed, as well as proposed developments for the start of Run-3 and beyond. The detailed efficiencies and resolutions for the trigger for a wide range of physics signatures are presented. These results demonstrate the continued excellent performance of the ID trigger in the extreme pile-up conditions of Run-2. During the current 2019-2021 long shutdown, the ATLAS High-Level Trigger software is being redesigned to cope with the running conditions of Run-3 and beyond, whilst maintaining or improving upon the excellent performance from Run-2. This poses significant challenges for the design of the algorithms in terms of execution time and physics performance. Following this redesign, the ID Trigger will continue to lie at the heart of the ATLAS trigger and to be central to the successful fulfilment of the ATLAS physics programme.

        Speaker: Marco Aparo (University of Sussex (GB))
        poster_maparo_LHCP2020.pdf
        Poster video explanation
        Zoom meeting room
      • 184
        The ATLAS Muon Trigger Design and Performance

        Muon triggers are essential for studying a variety of physics processes in the ATLAS experiment, including both standard model measurements and searches for new physics. The ATLAS muon trigger consists of a hardware-based system (Level-1), as well as a software-based reconstruction (High-Level Trigger). The muon triggers have been optimised during Run 2 to provide a high efficiency while keeping the trigger rate low. We will present an overview of how we trigger on muons, recent improvements, the performance of the muon trigger in Run 2 data and the improvements underway for Run 3.

        Speaker: Alec Swenson Drobac (Tufts University (US))
        Drobac_LHCP2020_MuonTriggerPoster.pdf
        Poster video explanation
        Zoom Meeting Room
      • 185
        The ATLAS trigger menu: from Run 2 to Run 3

        The ATLAS experiment aims to record about 1 kHz of physics collisions. This is achieved by using a two-level trigger system to select interesting physics events while reducing the data rate from the 40 MHz LHC crossing frequency. Events are selected based on physics signatures such as the presence of energetic leptons, photons, jets or large missing energy. The wide physics programme carried out by ATLAS is achieved by running around 1000 triggers during data taking. A Trigger Menu is the compilation of these triggers, specifying the physics selection algorithms to be used during data taking and the rate and bandwidth a given trigger is allocated. Trigger menus must reflect the physics goals for a given run, and also must take into consideration the instantaneous luminosity of the LHC and limitations from the ATLAS detector readout and offline processing farm. We will describe the design criteria for the ATLAS trigger menu. We discuss several aspects of the process of planning the trigger menu, including how rate, bandwidth, and CPU constraints are folded in during the compilation of the menu. Improvements made during the run to react to changing LHC conditions and data taking scenarios are discussed and we conclude with an outlook on how the trigger menu will evolve with the detector upgrades currently being installed for the start of Run 3.

        Speaker: Emma Torro Pastor (Univ. of Valencia and CSIC (ES))
        LHCP2020_triggerMenu_poster.pdf
        Poster video explanation
        Zoom meeting room
      • 186
        The Fast Interaction Trigger Upgrade for ALICE

        In preparation for LHC Run 3 ALICE will upgrade its subsystems to cope with the increased interaction rate of 50 kHz in Pb-Pb and up to 1 MHz in other collision systems, resulting in the data throughput from the detector up to 3 TB/s. Storing and analyzing such amount of data is a significant challenge and therefore, the online event selection will be required.

        The Fast Interaction Trigger (FIT) will generate minimum-bias and multiplicity triggers with maximum latency of 400 ns. It will measure the time of collision with resolution better than 40 ps. Moreover, FIT will serve as the main ALICE luminometer, providing direct, real-time feedback to the LHC for beam tuning. It will be also used to reconstruct vertex position, forward particle mutliplicity, centrality and event plane, as well as study diffractive physics at forward rapidity.

        FIT consists of three detector subsystems: the FT0, a fast Cherenkov detector array, using MCPPMTs as photosensors; the FV0, a large scintillator ring with unique light collection system developed to avoid using wavelenght shifters; the FDD, Forward Diffractive Detector using scintillator with state-of-art fast wavelength-shifting fibers. Since the overall latency of the FIT outputs is constrained by about 400 ns the online event selection is performed with FPGA integrated circuits including high speed serial interfaces.

        We will present the FIT components and results of tests of fully-assembled FIT detectors. Moreover, the results of trigger simulations will be discussed.

        Speaker: Sebastian Bysiak (Institute of Nuclear Physics Polish Academy of Sciences (PL))
        poster_ALICE-FIT_Bysiak.pdf
        Poster video explanation
        Zoom meeting room
      • 187
        The Forward Diffractive Detector for ALICE

        ALICE (A Large Ion Collider Experiment) is one of the four main detectors at CERN LHC. In order to exploit the increased luminosity and interaction rate during the upcoming LHC Run 3 and 4, ALICE is now implementing a significant upgrade of its detectors and systems.

        The minimum latency interaction trigger, luminosity monitoring, precision collision time, and determination of centrality and event plane for heavy-ion collisions will be provided by the Fast Interaction Trigger (FIT). FIT consists of three subsystems, among them the Forward Diffractive Detector (FDD).

        In this work, we introduce the FDD, which is the upgrade of the former ALICE Diffractive (AD) detector. The FDD detector consists of two stations covering the pseudorapidity ranges of 4.7<η<6.3 and -6.9<η<-4.9, respectively. This coverage allows FDD to efficiently tag diffractive and ultraperipheral events. The stations are made of two layers of plastic scintillators, divided into four quadrants. Each quadrant has two wavelengths shifting (WLS) bars connected to individual PMTs via a bundle of clear optical fibres. Among the main improvements of the FDD, with respect to the AD, are faster plastic scintillators and WLS, and the use of the newly developed front-end electronics suitable for operation both in a triggered and in a continuous readout mode.

        The FDD will ensure that ALICE has the large pseudorapidity coverage needed to (1) select diffractive events down to diffractive masses of a few GeV/c^2, and (2) to veto particle production in the forward regions in order to obtain clean samples of ultra-peripheral events.

        Speaker: Solangel Rojas (Czech Technical University (CZ))
        Cernbox-Video Poster overview
        Poster_LHCP_2020.pdf
        Poster room (Zoom)
        Video - Poster overwiew
      • 188
        The Forward Search Experiment

        Although the Standard Model successfully explains most phenomena at the LHC, there are several outstanding questions, including the nature of dark matter, the origin of neutrino masses, and the asymmetry in matter and anti-matter abundances in the Universe. Located in the side tunnel TI12, FASER (Forward Search Experiment) will search for highly displaced signals from light and extremely weakly interacting particles that can be copiously produced in proton-proton collisions at the LHC. After their production at the ATLAS interaction point, light long-lived particles move along the beam collision axis line of sight, and then may decay within the volume of FASER into visible Standard Model particles.

        During the long shutdown, the FASER experiment will complete the hardware and software module production and commissioning and be installed underground. In Run 3 during 2021-2024, the FASER detector will start taking data.

        The Tracker Interlock and Monitoring (TIM) board is produced to monitor the condition of the FASER tracker stations. If the temperature exceeds the normal range, the TIM board will send a hardware interlock signal to the LV and HV power supply, and the power supply will be turned off to protect the tracker station. Temperature and humidity data read from TIM will also be sent to DCS for further processing.

        Speaker: Di Wang (Tsinghua University (CN))
        LHCPposter_DiWang.pdf
        recording.m4a
        Zoom room for DI Wang's LHCP room for DI Wang's LHCP meetin
      • 189
        The phase-1 upgrade of the ATLAS level-1 calorimeter trigger

        The ATLAS level-1 calorimeter trigger (L1Calo) is a hardware-based system that identifies events containing calorimeter-based physics objects, including electrons, photons, taus, jets, and missing transverse energy. In preparation for Run 3, when the LHC is expected to run at higher energy and instantaneous luminosity, L1Calo is currently implementing a significant programme of planned upgrades. The existing hardware will be replaced by a new system of feature extractor (FEX) modules, which will process finer-granularity information from the calorimeters and execute more sophisticated algorithms to identify physics objects; these upgrades will permit better performance in a challenging high-luminosity and high-pileup environment. This talk will introduce the features of the upgraded L1Calo system and the plans for production, installation, and commissioning. In addition, the expected performance of L1Calo in Run 3 will be discussed.

        Speaker: Silvia Franchino (Ruprecht Karls Universitaet Heidelberg (DE))
        Poster_Franchino_ATLAS_L1CaloUpgrade_LHCP2020.pdf
        Poster presentation
        Zoom meeting room
      • 190
        The Two Hemisphere Method for Searches of Multijet BSM Signals

        A new method for identifying hints of possible beyond the standard model (BSM) signals with energetic high jet multiplicity final states is proposed. In particular, the QCD background is estimated in a data driven way. Based on the simplified picture where QCD multijet events are created from a 2$\to$2 process followed by cascade branching of the outcoming partons, the proposed “Two Hemisphere Method” (THm) divides events to two hemispheres and predicts the distribution of the number of jets in a predefined high multiplicity signal region. Validation of the above-mentioned assumption was performed using LO, NLO, and NNLO simulations, showing no effect of higher order calculations on the prediction accuracy.

        The sensitivity of a search based on the proposed procedure was examined on two topologically distinct scenarios: micro-Black Hole (mBH) and R-parity violating (RPV) SUSY models. The THm was not efficient on mBH due to signal contamination in the supposed signal free control region. Sensitivity for RPV SUSY showed comparable sensitivity to other methods used in previous analyses. Since the sources of the uncertainties in this new approach are very different from the current methods, the procedures complement one another.

        Speaker: Daniel Turgeman (Weizmann Institute of Science (IL))
        LHCP poster.pdf
        THm Poster Video.mp4

        I will be available for contact by email: Daniel.Turgeman@weizmann.ac.il

      • 191
        UPC: a powerful tool for J/$\Psi$ photoproduction analysis in ALICE

        Ultraperipheral Collisions (UPC) occur when the interacting nuclei or protons have an impact parameter larger than the sum of their radii. They are mediated by virtual photon exchange. The photoproduction of heavy vector mesons is especially interesting because they couple to the photon.

        The ALICE Collaboration has analysed both p-Pb and Pb--Pb UPC at the centre-of-mass energy of $\sqrt{s_{\rm NN}} = 5.02\text{ TeV}$, which correspond to $\gamma$p and $\gamma$-Pb interactions, respectively. This poster discusses the exclusive photoproduction of J/$\Psi$ off proton and Pb targets, respectively, which shed light on the occurrence of saturation and nuclear shadowing.

        In more detail, the p-Pb results describe the growth of the cross section for exclusive production over a wide range in Bjorken-$x$, from ${\sim}10^{-2}$ to ${\sim}10^{-5}$, while the Pb--Pb results demonstrate the presence of nuclear shadowing at high energies and low scales, i.e. of the order of the mass of the J/$\Psi$.

        Speaker: Simone Ragoni (University of Birmingham (GB))
        LHCPragoni_v7.pdf
        Poster video explanation
        Zoom meeting room
      • 192
        Z boson production in Pb--Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

        To compute cross sections in proton-proton collisions, parton distribution functions (PDFs) are used which describe the density of partons within the proton. In nuclear environments, such as heavy ions, these densities change and therefore PDFs must be modified to nuclear PDFs (nPDFs). Measurements of electroweak bosons help to constrain the nPDFs. This in turn allows to compute cross sections in heavy-ion collisions with higher precision.

        In this poster the Z-boson production is reported in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The measurement is done through the muonic decay channel. The normalized invariant yield is measured for dimuons with mass $60 < m_{\mu\mu} < 120$ GeV/$c^2$ and rapidity $2.5 < y < 4$. It is presented as a function of rapidity as well as collision centrality. The results are compared to different theoretical predictions of the parton distribution functions (both PDF and nPDF). A $3.4\sigma$ deviation is seen in the integrated yield between the data and the free PDFs (no nuclear modifications), while they are in agreement with the nPDF predictions. The differential data will serve as constraints for the nPDFs.

        Speaker: Sizar Aziz (Université Paris-Saclay (FR))
        SizarPosterLHCPv3.pdf
        Video presentation
        Zoom link
  • Friday 29 May
  • Saturday 30 May
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