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This is the kickoff event for a series of meetings, running throughout 2018, with plenary events and intermediate periods of working group activities.
The main goal of the Workshop is to review, extend and further refine our understanding of the physics potential of the High Luminosity LHC.
The workshop aims to stimulate new ideas for measurements and observables, to extend the LHC discovery reach, to improve the modeling of LHC phenomena towards measurements at ultimate precision, and to prepare to exploit the HL-LHC data to the fullest possible extent.
The Workshop will also provide the opportunity to begin a more systematic study of physics at the HE-LHC, a new pp collider in the LHC ring with CM energy in the range of 27 TeV.
The activity of the Workshop will extend over a one year period, driven by working groups covering the following areas:
QCD, EW and top quark physics
Higgs and EWSB
BSM
Flavour
Heavy Ions
The results of the Workshop will be documented in a Yellow Report, to be completed in time (~end 2018) for submission to the next review of the European strategy for particle physics.
The deadline to reserve pre-booked rooms in the CERN Hostel has expired. To book a room, please contact directly the Hostel.
Ongoing work is being discussed on the wiki.
To join the mailing list of the Workshop, click here
A welcome drink for registered participants will be offered in the area adjacent the Main Auditorium, where we shall also display the submitted posters.
Posters will remain visible for the whole duration of the workshop
We study $gg\to\gamma\gamma$ amplitudes by including $t\bar t$ bound-state effects near their mass threshold. In terms of the non-relativistic expansion of the amplitude, the LO contribution is an energy-independent term in the one-loop amplitude, and a part of the NLO contribution is described by the non-relativistic Green function. We find that due to the interference of these terms, the diphoton mass spectrum shows a characteristic dip-and-bump shape near the threshold. In addition, the position of the dip and the bump is determined by the 1S mass of the $t\bar t$ resonance which is well predicted in terms of the short-distance mass of top-quark in NRQCD. Thanks to the simple and clean nature in its experimental measurement, it can give a superior method to determine the top-quark short-distance mass at hadron colliders.
The LHCb experiment is designed to perform high precision measurements of matter-antimatter asymmetries and searches for rare and forbidden decays, with the aim of discovering new and unexpected particles and forces. In 2030 the LHC beam intensity will increase by a factor of 50 compared to current operations. This means increased samples of the particles we need to study, but it also presents experimental challenges. In particular, with current technology it becomes impossible to differentiate the many (>50) separate proton-proton collisions which occur for each bunch crossing. A Monte Carlo simulation was developed to model the operation of a silicon pixel vertex detector surrounding the collision region at LHCb, under the conditions expected after 2030, after the second upgrade of the Vertex Locator(VELO).The main goal was studying the effect of adding '4D' detectors which save high-precision timing information, in addition to the usual three spatial coordinates, as charged particles pass through them. With the additional information on the particle timing, it is possible to separately reconstruct the individual 50+ collisions, allowing the next generation of high-precision measurements to be made at the LHCb.
Semileptonic beauty decays provide a theoretically clean probe of CKM Unitarity since their decay rates factorise into leptonic and hadronic currents. At hadron colliders the full kinematic properties of these decays cannot be determined due to the unreconstructable neutrino. The kinematics can however be inferred through the conservation of momentum perpendicular to the flight direction that can be resolved by the LHCb Vertex Locator (VELO). The RF foil is an essential component of the LHCb vertex locator (VELO), separating the secondary vacuum of the VELO from the primary vacuum of the LHC. The foil protects the VELO modules from beam induced effects such as RF waves, and protects the LHC vacuum from hardware effects such as outgassing. The RF foil contributes to the material budget of the experiment and degrades the quality of tracks resulting in a worsened resolution for the reconstructed production and decay vertices. The phase-II upgrade can greatly improve the performance of semileptonic measurements at LHCb. The additional luminosity provided by the LHC coupled with advances in LHCb’s hardware and detector design will allow us to probe previously unobserved decays, while improving our understanding of decays currently under investigation. Improvements in the VELO design will improve the resolution of production and decay vertices, significantly improving the physics performance of semileptonic measurements. In addition, the removal, or thinning, of the RF foil can allow the resolution of measured vertices to be improved even further, while simultaneously improving background rejection, tracking efficiencies and reducing ghost rates. The physics performance increase, solely from improved resolution on semileptonic kinematics due to the removal of the RF foil is estimated.
Observing double Higgs production (HH) will enable a direct determination of the Higgs self-coupling, a crucial parameter of the Standard Model. Given the extreme small rate of this process, detecting it will only be possible with the HL-LHC and the 3 ab-1 of data it is expected to provide, and with an upgraded CMS detector capable to cope with high levels of radiation and pileup. Sensitivity studies on HH, based on the projected performance of the CMS Phase II detector, as well as extrapolations of Run 2 searches for HH production to the ultimate HL-LHC luminosity, are presented.
The upgraded CMS detector at the HL-LHC will allow the properties of the Higgs boson to be measured with unprecedented precision. This poster presents the expected performance of Higgs measurements in the diphoton decay channel using the upgraded CMS detector. Current CMS analyses and near-term plans are summarised. Recent studies of the projected diphoton mass resolution at the HL-LHC, taking into account the proposed barrel calorimeter upgrade and potential timing capabilities, are discussed. In addition, extrapolations of Run 2 measurements to the full HL-LHC dataset are presented under different scenarios.
Several theoretical models inspired in the idea of supersymmetry (SUSY) accommodate the possibility of HSCPs (Heavy Stable Charged Particles). The phase-II upgrade of the CMS-RPC system will allow the trigger and identification of these kind of particles exploiting the Time of Flight Technique with the improved time resolution that a new DAQ system will provide (~1ns). Moreover new RPC chambers will be installed to extend the acceptance coverage up to $|\eta|<2.1$ with similar time resolution and better space resolution to complement this search.
In this poster a trigger strategy to detect HSCPs with the RPC detectors is presented, its performance is studied with Monte Carlo simulations and the expected results with the High Luminosity LHC data are shown.
The CMS experiment is in the process of designing a completely new track detector for the high-luminosity phase of LHC. The results of the future offline tracking performance of CMS will be shown in this poster, such as the excellent efficiency and the very good track separation in the core of a jet. Moreover, some recent developments using the Outer Tracker are included in the poster. The modules in the Outer Tracker of CMS in Phase 2 will provide a new type of hits, so-called vector hits, containing both position and direction information. In this way real tracks can be distinguished from purely random combination of hits. A new seeding is introduced in the Outer Tracker to reconstruct tracks coming from displaced vertices. Preliminary performance results will be presented.
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 studies of the expected performance of the reconstruction and identification of hadronic tau lepton decays using the ATLAS detector for the High Luminosity LHC (HL-LHC) upgrade.
The performance studies adapts the current ATLAS Tau algorithms to the specific beam conditions and detector upgrade expected for the HL-LHC
Top squark pair production in scenarios with compressed mass spectra are experimentally challenging. The reach at the high-luminosity phase of the LHC is expected to significantly extend beyond the current limits, when considering models where the top squarks decays via $\tilde{t}_{1} \rightarrow t\tilde\chi^0_1$. This poster presents benchmark studies targeting dileptonic final states with a parameterised simulation of the ATLAS detector at a centre-of-mass energy of 14 TeV.
Results are shown for an integrated luminosity of 3000 $fb^{-1}$
Real data as well as Monte Carlo simulations are used to study the decay of $B^0_s \to J/\psi\phi$ in order to measure the $CP$ violating mixing phase and the width difference between the $B^0_s$ eigenstates. The increased sensitivity is expected mainly due to the improved decay time resolution obtained with the ATLAS upgraded IBL and ITk inner tracking detector
Roman Pots are special devices that allow operation of detectors very close to the beam. This technique is used for measurements of forward protons, scattered in diffractive or electromagnetic interactions. Presently, several detectors housed in Roman Pots operate at LHC. The poster presents the physics motivation and first feasibility studies for such detectors the HL-LHC
Instantons are nonperturbative tunneling processes between topologically distinct vacua which occurs in non-Abelian gauge theories. Even though instanton processes are a core prediction of the SM, providing insights in the vacuum structure of the theory, they have so far not been experimentally observed. Instanton processes in the electroweak sector (sphalerons) lead to violation of baryon+lepton number, and have important implications for baryogenesis. While their cross-section is predicted to be vanishingly small at LHC energies, sphalerons might be in reach of upcoming high energy colliders, such as the HE-LHC. We present promising search strategies for sphaleron production, based on the large predicted multiplicity of gauge bosons and the expected upper limits on their cross-section achievable at both the high luminosity and high energy LHC. In the QCD sector instantons lead to chirality violation and are thought to play a role in many aspects of the long distance behaviour of the theory.
QCD instantons have been searched for in ep scattering at HERA, but insofar they have not been looked for in pp collisions, where their cross-section is predicted to be enhanced. We discuss possible search strategies for both the LHeC and HL/HE-LHC
The HH->bbγγ is a promising channel to measure the trilinear Higgs self-coupling, benefitting from the narrow mass peak of the H->γγ decay and the large branching fraction of the H->bb decay. The prospects for observing di-Higgs production through the bbγγ channel in the HL-LHC are presented. This study assumes an integrated luminosity of 3000 fb-1 and mean pileup rates < μ > of 200. An expected significance of 1.05 is obtained in HH->bbγγ observation which translates into the Higgs boson self-coupling being constrained to -0.8 < 𝜆/𝜆SM < 7.7 at 95% confidence level.