Activities

Dr Tim Scanlon

Position

Royal Society University Research Fellow

Research Activities

Higgs, Exotic Searches, Flavour Tagging, Phenomenology, Data Intensive Science

Leadership Roles

Director of Research: Centre for Doctoral Training in Data Intensive Science
Convener of ATLAS H->bb SubGroup
Convener of ATLAS Flavour Tagging Group
Convener of DZero Low Mass Higgs Group
Covener of DZero Flavour Tagging Group

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Activities and Results

Physics

UCL people are very active in the ATLAS Standard Model, Higgs and Exotics groups.

On analysis activities, we have provided leaders of the Standard Model group (Jon Butterworth, Oct 2010-2012) Soft QCD (Emily Nurse, April 2010-2011) and Jet (Mario Campenelli (April 2010-2011) Higgs bb (Tim Scanlon, current) Exotics with leptons (K.Leney, current) subgroups. We also provided leadership of performenace and trigger groups

Jets and SM physics

The group is very active in measuring production and properties of hadronic jets, as well as vector bosons either decaying into jets or produced in association with them

• Charged particle multiplicities 900 GeV
• Charged particle multiplicities 7 TeV
• Charged particle correlations
• Inclusive and dijet cross sections
• Measurement of dijet production with a veto on additional central jet activity in pp collisions at sqrt(s)=7 TeV using the ATLAS detector
• Jet veto and azimuthal decorrelations
• Inclusive jet cross sections
• B-jet cross sections
• Cross-section for hadronically-decaying boosted vector bosons
• Z bosons plus b-jet cross sections
• ZZ cross-section

Higgs physics

We are mainly working on the most common, but most difficult, Higgs decay channel, where the Higgs boson produces a pair of b quarks. Due to the enormous background, this channel is only feasible when the Higgs is produced in association with other particles.

• VH (H-> bb) searches
• HH->bbbb searches

Searches for exotic physics

We mainly work on the search for resonances in the dijet final state, either for the case of light jets or jets coming from the hadronic decay of energetic vector bosons.

• Search for new phenomena in dijets
• Search for new resonances decaying into hadronically-decaying vector bosons
• Combination of searches for WW, WZ and ZZ resonances
• New Physics with jets + MET
• Search for long-lived heavy neutral leptons

Phenomenological studies

The group has recently concentrated in jet substructure, and on interpreting standard model measurements in terms of new physics.

• Constraining BSM models with detector-corrected data
• Jet substructure as a new search channel for the Higgs at the LHC, J M Butterworth, A R Davison, M Rubin and G P Salam
  arXiv:0802.2470 [hep-ph] Physical Review Letters 100, 242001 (2008) : UCL.
• The Underlying Event and the Total Cross Section from the Tevatron to the LHC
  M Baehr, J M Butterworth and M H Seymour, arXiv:0806.2949 [hep-ph].
• JIMMY -- Underlying Event Simulation for HERWIG and MC@NLO
• KtJet -- First OO implementation of the kt jet clustering algorithm (now superseded by fastjet)
• HZTool -- Robust Data/MC Comparison Tool
• Rivet -- OO replacement for HZTool
• CEDAR -- Collaborative EScience Data Analysis Resource
• Standard Model Handles and Candles Working Group: Tools and Jets Summary Report C. Buttar et al. arXiv:0803.0678 [hep-ph] UCL.
• Reconstructing Sparticle Mass Spectra using Hadronic Decays Jon Butterworth, John Ellis, Are Raklev, hep-ph/0702150 JHEP05 033 (2007).
• "Measuring Slepton Spin at the LHC", A.J.Barr (JHEP02(2006)042. Nov 2005)
• WW Scattering at the LHC ( paper ), by J.M.Butterworth, B.E.Cox and J. R. Forshaw, June 2001.

Jet performancs

We are very active on the jet substructure group, to identify the origin of jets (light quarks, gluons, vector bosons) looking at the distribution of their constituents.

• Identification of boosted, hadroncically decaying W bosons and comparison with data

B-tagging performancs

• We have strong involvement in the b-tagging group, especially regarding tracking in dense environments and searches for b-quark pairs inside a jet

Trigger/DAQ

We are strongly involved in the jet trigger, its software, performance determination and improvements for the new data taking. We still maintain some involvement in the high-level track trigger.

• Performance of the jet trigger during Run 1
• IDScan -- Tracking aglorithms for the Level 2 Trigger
• ROS -- ATLAS ReadOut Subsystem software / modelling

Offline Software

UCL is in charge of the ATLANTIS event display and of the real-time tester RTT. We have also been involved in the fast simulation

• Atlfast -- The ATLAS fast simulation
• Performance of the ATLAS fast simulation ATLFAST Cavalli, D; Costanzo, D; Dean, S; Duehrssen, M; Hassani, S; Heldmann, M; Jakobs, K; Nairz, A; Phillips, A; Resconi, S; Richter-Was, E; Sherwood, P; Vacavant, L; Vivarelli, I; De Vivie de Regie, J B; Wingerter-Seez, I.
• JiveXML -- The interface package between Athena and the Atlantis Event Display
• Atlantis -- The ATLAS Event display
• RTT -- Run Time Testing of ATLAS software
• YSplitter : An Athena tool for studying jet substructure, Butterworth, J M; Davison, A; Ozcan, E; Sherwood, P ATLAS-PHYS-INT-2007-015 (ATLAS internal, password needed)

SCT

We participated to the contruction of the Silicon Vertex Tracker, the main component of the ATLAS central detector.

• Electronics -- Clock and Control hardware. (TIM webpage here)
• Mechanical Engineering
• Commissioning the SCT at CERN
• SctRodDaq -- the SCT readout software
• The data acquisition and calibration system for the ATLAS Semiconductor Tracker
  A Abdessalam et al, JINST 3 P01003 : UCL.

Upgrades

• The group has a strong involvement and a leaderhip position in the Phase-II upgrade of the ATLAS trigger system to be able to reconstruct tracks at Level-1.