Matt LeBlanc

ATLAS Collaboration

Postdoctoral Research Associate, University of Arizona

Ph.D. Victoria '17

Publications and Public Results

Click entries with a for more info!

LHC Run 2

Latest: Summer 2018

ATLAS Collaboration, Combination of the searches for pair-produced vector-like partners of the third-generation quarks at sqrt(s) = 13 TeV with the ATLAS detector.
ATLAS-EXOT-2017-17, submitted to PRL. (arXiv:1808.02343).
ATLAS Collaboration, Search for new phenomena in events with same-charge leptons and b-jets in pp collisions at sqrt(s) = 13 TeV with the ATLAS detector.
ATLAS-EXOT-2016-16, submitted to JHEP. (arXiv:1807.11883).

ATLAS Collaboration, In situ calibration of large-R jet energy and mass in 13 TeV proton-proton collisions with the ATLAS detector.
ATLAS-JETM-2018-02, submitted to EPJC. (arXiv:1807.09477).


Large-radius jets are fantastic tools, but they have not historically been associated with precision. Using the calibration techniques we apply to R=0.4 jets on groomed R=1.0 jets; however, we can reduce uncertainties on their energy scale to the percent-level. This correction is also found to correct the large-R jet mass scale to within the limits of our current precision. The energy correction derived from light quark and gluon jets is also found to correct the energy scale of large-R jets originating from high-pT W bosons and top quarks.


I was a contact person for this effort, which involved a large number of teams from a diverse set of ATLAS institutes. I also run part of the calibration chain, which corrects the response of jets in the forward region using well-measured jets in the central region.


ATLAS Collaboration, Search for gluino-mediated stop and sbottom pair production in events with b-jets and large missing transverse momentum.
ATLAS-CONF-2018-041, Conference Note (SUSY 2018).
ATLAS Collaboration, Impact of Pile-up on Jet Constituent Multiplicity in ATLAS
ATL-PHYS-PUB-2018-011, Public Note released for BOOST 2018.
ATLAS Collaboration, Combination of the searches for pair-produced vector-like partners of the third generation quarks at sqrt(s) = 13 TeV with the ATLAS detector.
ATLAS-CONF-2018-032, Conference Note (ICHEP 2018).

Older results

ATLAS Collaboration, Search for Supersymmetry in final states with missing transverse momentum and multiple b-jets in proton-proton collisions at sqrt(s)=13 with the ATLAS detector.
ATLAS-SUSY-2016-10, JHEP 06 (2017) 107 (arXiv:1711.01901).

ATLAS Collaboration, Impact of Alternative Inputs and Grooming Methods on Large-R Jet Reconstruction in ATLAS
ATL-PHYS-PUB-2017-020, Public Note (2017).


We have a lot of experimental flexibility when reconstructing jets. The choice of inputs, the recombination algorithm, the size, which grooming algorithm to apply ... each could in principle be selected by the user. So how do we know which options are the best ones?

This note summarises our efforts to understand how choosing different jet inputs and grooming methods impacts the performance of the large-radius jets we reconstruct in ATLAS, by comparing the performance of 464 different jet collections in terms of pile-up stability and jet substructure performance.



Also included are the first public studies using our DigiTruth tool, which propagates cell-level information about the true origin of energy deposits in the ATLAS calorimeter through the reconstruction process for our simulated events. Here, we show that for moderate levels of μ, pile-up tends to add new clusters rather than adding information to those created by the hard-scatter interaction.



ATLAS Collaboration, Jet reclustering and close-by effects in ATLAS Run 2.
ATLAS-CONF-2017-062, Conference Note (BOOST 2017).


One property of jet reconstruction algorithms is that they are agnostic to the nature of the input constituents. In ATLAS, we reconstruct jets from topo-clusters, tracks, truth-particles, and even smaller jets!

By using well calibrated R=0.4 jets as the inputs to jet finding, we can capitalise on our detailed understanding of these objects and the precision of the calibration which we apply to them. This also allows the large-R jet radius to be optimised in the context of searches.



I was a contact for this result, and the main analyser for many of the studies documented here. Jet reclustering has been widely used in the ATLAS SUSY and Exotics groups throughout Run 1 and 2 of the LHC, and was even utilised in certain channels studying the recently-observed ttH process!


ATLAS Collaboration, Search for pair production of gluinos decaying via top or bottom squarks in events with b-jets and large missing transverse momentum in pp collisions at sqrt(s)=13 TeV with the ATLAS detector
ATLAS-CONF-2016-052, Conference Note (ICHEP 2016).
ATLAS Collaboration, Search for pair production of gluinos decaying via stop and sbottom in events with b-jets and large missing transverse momentum in pp collisions at sqrt(s) = 13 TeV with the ATLAS detector.
Physical Review D 94, 032003 (2016). (arXiv:1605.09318).
ATLAS Collaboration, Search for gluino-mediated stop and sbottom pair production in events with b-jets and large missing transverse momentum in sqrt(s)=13 TeV pp collisions with the ATLAS detector
ATLAS-CONF-2015-067, Conference Note (CERN End-of-Year Event 2015).

LHC Run 1

ATLAS Collaboration, Identification of high transverse momentum top quarks in pp collisions at sqrt(s) = 8 TeV with the ATLAS detector.
Journal of High Energy Physics, 06, 093 (2016). (arXiv:1603.03127).
ATLAS Collaboration, Identification of high transverse momentum top quarks in pp collisions at sqrt(s) = 8 TeV with the ATLAS detector.
ATLAS-CONF-2015-036, Conference Note (BOOST 2015).
ATLAS Collaboration, Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at sqrt(s) = 8 TeV with the ATLAS detector.
Journal of High Energy Physics, 09, 015 (2014).

Proceedings & other publications


M. LeBlanc (on behalf of the ATLAS collaboration), Inclusive searches for squarks and gluinos with the ATLAS detector.
Proceedings, 26th International Workshop on Deep-Inelastic Scattering and Related Topics (DIS 2018) : Kobe, Japan, 16-20 April 2018. (in prep.) pre-print on CDS.


Despite the absence of experimental evidence, TeV-scale supersymmetry remains one of the best-motivated and studied Standard Model extensions. These proceedings briefly summarise recent ATLAS results on inclusive searches for supersymmetric squarks and gluinos, and highlight new interpretations of these results which are revealing new places SUSY may still be hiding.



Ryan P Taylor, Frank Berghaus, Franco Brasolin, Cristovao Jose Domingues Cordeiro, Ron Desmarais, Laurence Field, Ian Gable, Domenico Giordano, Alessandro Di Girolamo, John Hover, Matthew LeBlanc, Peter Love, Michael Paterson, Randall Sobie, Alexandr Zaytsev, The evolution of cloud computing in ATLAS.
Proceedings, 21st International Conference on Computing in High Energy and Nuclear Physics (CHEP 2015) : Okinawa, Japan, 13-17 April 2015. Published in Journal of Physics: Conference Series, Volume 664, Clouds and Virtualization (CDS).


The ATLAS experiment has successfully incorporated cloud computing technology and cloud resources into its primarily grid-based model of distributed computing. These proceedings included some of the results of my ATLAS authorship qualification project, which was to evaluate and compare the performance of commercial clouds (such as Google GCE and Amazon EC2) using HEP-specific benchmarks.

Public Presentations

Matt LeBlanc (on behalf of the ATLAS Collaboration), Inclusive searches for squarks and gluinos with the ATLAS detector.
Presentation at 26th International Workshop on Deep-Inelastic Scattering and Related Topics (DIS 2018) : Kobe, Japan, 16-20 April 2018.
Slides, ATL-PHYS-SLIDE-2018-180.
Matt LeBlanc (on behalf of the ATLAS Collaboration), Impact of Alternative Inputs and Grooming Methods on Large-R Jet Reconstruction in ATLAS.
Presentation at 133rd LHCC Meeting : CERN, Geneva, CH, 28 February - 1 March 2018.
Poster, ATL-COM-PHYS-2018-106.
Matt LeBlanc (on behalf of the ATLAS Collaboration), Jet reclustering and close-by effects in ATLAS Run 2.
Presentation at 8th International Workshop on Boosted Object Phenomenology, Reconstruction and Searches in HEP (BOOST 2017) : Buffalo, NY, USA, 16-21 July 2017.
Poster, ATL-PHYS-SLIDE-2017-572.
Matt LeBlanc (on behalf of the ATLAS Collaboration), ATLAS boosted object tagging.
Presentation at 7th International Workshop on Boosted Object Phenomenology, Reconstruction and Searches in HEP (BOOST 2015) : Chicago, IL, USA, 10-14 August 2015.
Slides, ATL-PHYS-SLIDE-2015-660.

Teaching and outreach

TRIUMF
2015, 2014, 2013 Public Tour Guide
2015, 2014 ISAC-II Station Guide Emily Carr Artists-in-Residence Visits
Spring 2014 Instructor ATLAS Masterclass @ TRIUMF
2013 Photographer TRIUMF Open House
University of Victoria
Spring 2012 Instructor ATLAS Masterclass @ UVic
Winter 2012 Lab Instructor Physics 112, Introductory Physics II
Fall 2011 Lab Instructor Physics 112, Introductory Physics I
Acadia University
Winter 2010 Teaching Assistant Math 2723, Introductory Differential Equations
Lab Assistant Physics 1063, General Physics II
Studio Assistant Math 1023, Introductory Calculus II
Fall 2009 Lab Assistant Physics 1053, General Physics I
Winter 2009 Lab Assistant Physics 1023, Introductory Physics II
Fall 2008 Physics Drop-in Help Center Tutor

Contact

I'm currently based at CERN, and the contact information found here should typically be up-to-date. If you want to reach me directly, you can also send me an e-mail or tweet directly. If you're interested in collaborating, github is probably the best place to start. If you want to race, I'll see you on strava.