Contact
Name
Loc Quertenmont
Position
Former member
Postdoc in CP3 from September 2006 to May 2015
My personal homepage
Projects
I am involved in the following research directions:

CMS Tracker commissioning and performance assessment

The CMS silicon strip tracker is the largest device of its type ever built. There are 24244 single-sided micro-strip sensors covering an active area of 198m2.
Physics performance of the detector are being constantly assessed and optimized as new data comes.
Members of UCL are playing a major role in the understanding of the silicon strip tracker and in the maintenance and development of the local reconstruction code.

External collaborators: CMS tracker collaboration.

Particle Identification with ionization energy loss in the CMS experiment at the LHC

The CMS detector at the LHC can be used to identify particles via the measurement of their ionization energy loss. The sub-detectors that have provided so far useful information for this experimental technique are the silicon strip tracker and the pixel detectors. Identification of low momentum hadrons and detection of new exotic massive long-lived charged particles have all benefited from this experimental method. Members of UCL pioneered this technique in the early LHC times and have been developing the tools for its use and calibration. Since 2010 particle identification with ionization energy loss has been the basis of the CMS inclusive search for new massive long-lived charged particles, which has been providing the most stringent and model-independent limits existing to date on any model of new physics predicting such particles.

External collaborators: CMS collaboration.

Past projects
Hide past projects.

I am involved in the following research directions:

FROG: software for detector and event visualization

FROG is a generic framework dedicated to visualize events produced in particle collisions and detected by particle detectors.
It has been written in C++ and use OpenGL cross-platform libraries. It can be used to any particular physics experiment or detector design. The code is very light and very fast and can run on various Operating System. Moreover, FROG is self consistent and does not require installation of ROOT or Experiment software (e.g. CMSSW) libraries on user's computer.
It includes a lot of features based on an unique and powerful principle. Some of the functionalities are listed below :
3D and 2D visualization, graphical user interface, mouse interface, configuration files, production of pictures in various format, integration of personal objects.
One of the FROG application is to display events for one of the most complex physics experiment : the CMS experiment. But it works as well and even faster with smaller experiment like the Gastof detector.

Frog WebSite
CMS TWiki Page

Higgs bosons to ZZ -> 2l 2nu and measurement of the Higgs natural width

The final state containing two Z bosons decaying into a pair of leptons and a pair of neutrinos has been exploited by the CMS experiment at the LHC to produce a number of results related to the Higgs boson, including measurements of related standard model cross sections.

Constraints have been set on the total width of the 125 GeV Higgs boson, using its relative on-shell and off-shell production and decay rates to a pair of Z bosons, where one Z boson decays to an electron or muon pair, and the other to an electron, muon, or neutrino pair. The analysis is based on the data collected by the CMS experiment at the LHC in 2011 and 2012. A simultaneous maximum likelihood fit to the measured kinematic distributions near the resonance peak and above the Z-boson pair production threshold leads to an upper limit on the Higgs boson width of < 22 MeV at a 95% confidence level, which is 5.4 times the expected value in the standard model at the measured mass of 125.6 GeV.

A search for heavy Higgs bosons in the H → ZZ → 2l2ν decay channel, where l = e or , has also been performed using data collected in 2015 and 2016 at the center of mass energy of 13 TeV. No significant excess is observed above the background expectation. The results are interpreted to set exclusion limits on a number of extensions of the standard model scalar sectors: models with an additional electroweak singlet, as well as Type-I and Type-II two-Higgs doublets models.

External collaborators: CMS collaboration.

Simulation of the CMS silicon tracker

The Tracker Simulation group is responsible for the Geant-based simulation of the Pixel and Strip Tracker response, material budget and geometry description.
Members from CP3 are concentrating on various aspects of the validation with data. We also share the convenership of the group.

External collaborators: CMS tracker collaboration.

Publications in CP3
All my publications on Inspire

2016

Constraints on the Higgs boson width from off-shell production and decay to Z-boson pairs
Khachatryan, Vardan and others
[Abstract] [PDF] [Journal]
Refereed paper. 6th October.
Search for long-lived charged particles in proton-proton collisions at sqrt(s) = 13 TeV
Khachatryan, Vardan and others
[Abstract] [PDF] [Journal] Submitted to Phys. Rev. D
6th October.
Search for Neutral Resonances Decaying into a Z Boson and a Pair of b Jets or Tau Leptons
CMS collaboration
[Abstract] [PDF] [Journal] [Full text] Published in Phys. Lett. B 759 (2016) 369
Refereed paper. 28th April.
Summary results of high mass BSM Higgs searches using CMS run-I data
CMS Collaboration
[Full text] CMS Physics Analysis Summary CMS-PAS-HIG-16-007,
Public experimental note. 22nd April.
Search for a heavy scalar boson decaying into a pair of Z bosons in the 2ℓ2ν final state
CMS Collaboration
[Full text] CMS Physics Analysis Summary CMS-PAS-HIG-16-001
Public experimental note. 22nd April.
Searches for Long-lived Charged Particles in Proton-Proton Collisions at √s = 13 TeV
CMS Collaboration
[Full text] CMS Physics Analysis Summary CMS-PAS-EXO-15-010
Public experimental note. 22nd April.

2015

Search for H/A decaying into Z and A/H, with Z-->ll and A/H-->bb or A/H-->tau tau
CMS Collaboration
[Full text] CMS-PAS-HIG-15-001
Public experimental note. 1st December.
Simplified Models for Exotic BSM Searches
Heisig, Jan and Lessa, Andre and Quertenmont, Loic
[Abstract] [PDF] [Journal]
31st August.
Constraints on the pMSSM, AMSB model and on other models from the search for long-lived charged particles in proton-proton collisions at sqrt(s) = 8 TeV
Khachatryan, Vardan and others
[Abstract] [PDF] [Journal]
Refereed paper. 10th February.

2014

Reinterpreting the results of the search for long-lived charged particles in the pMSSM and other BSM scenarios
CMS Collaboration
[Full text]
Public experimental note. 1st July.
Projected Performance of an Upgraded CMS Detector at the LHC and HL-LHC: Contribution to the Snowmass Process
CMS Collaboration
[Abstract] [PDF]
Public experimental note. 1st July.
Search for invisible decays of a Higgs produced in association with a Z boson
CMS Collaboration
[Full text]
Public experimental note. 1st July.
Search for a heavy Higgs boson in the H -> ZZ -> 2l 2nu channel in pp collisions at sqrt(s) = 7 and 8 TeV
CMS Collaboration
[Full text]
Public experimental note. 1st July.
Measurement of electroweak production of two jets in association with a Z boson in proton-proton collisions at sqrt(s)=8 TeV
CMS Collaboration
[Full text]
Public experimental note. 1st July.
Evidence for the 125 GeV Higgs boson decaying to a pair of tau leptons
CMS Collaboration
[Abstract] [PDF] [Journal]
Refereed paper. 1st July.
Evidence for the direct decay of the 125 GeV Higgs boson to fermions
Chatrchyan, Serguei and others
[Abstract] [PDF] [Journal] Subjects: High Energy Physics - Experiment (hep-ex)
Journal reference: Nature Physics 10 (2014) 557
DOI: 10.1038/nphys3005
Report number: CMS-HIG-13-033, CERN-PH-EP-2014-004

Refereed paper. 1st July.

2011

Search for Heavy Stable Charged Particles in pp collisions at sqrt(s) = 7 TeV
The CMS Collaboration
[Abstract] [PDF] [Journal] Published in JHEP
Refereed paper. 8th February.

2010

CMS Tracking Performance Results from early LHC Operation
CMS collaboration
[Abstract] [PDF] [Journal] [Full text] Published in Eur.Phys.J.C70:1165-1192,2010.
Refereed paper. 21st December.

2009

Alignment of the CMS Silicon Tracker during Commissioning with Cosmic Rays
CMS Collaboration
[Abstract] [PDF] [Journal] [Full text] CMS PAPER CFT-09-003
Published in JINST

Refereed paper. 26th December.
Commissioning and Performance of the CMS Pixel Tracker with Cosmic Ray Muons
CMS Collaboration
[Abstract] [PDF] [Journal] [Full text] CMS-CFT-09-001.
Published in JINST

Refereed paper. 26th December.
Commissioning of the CMS Experiment and the Cosmic Run at Four Tesla
CMS Collaboration
[Abstract] [PDF] [Journal] [Full text] Published in JINST
Refereed paper. 21st December.
CMS Data Processing Workflows during an Extended Cosmic Ray Run
CMS Collaboration
[Abstract] [PDF] [Journal] [Full text] Published in JINST
Refereed paper. 21st December.
Commissioning and Performance of the CMS Silicon Strip Tracker with Cosmic Ray Muons
CMS Collaboration
[Abstract] [PDF] [Journal] [Full text] Published in JINST
Refereed paper. 21st December.
Stand-alone Cosmic Muon Reconstruction Before Installation of the CMS Silicon Strip Tracker
CMS Tracker Collaboration (W. Adam et al.).
[Abstract] [PDF] [Journal] [Full text] Published in JINST 4:P05004,2009
Refereed paper. 21st December.
Alignment of the CMS Silicon Strip Tracker during stand-alone Commissioning.
W. Adam et al.
[Abstract] [PDF] [Journal] Published in JINST 4:T07001,2009
Refereed paper. 21st December.
FROG: The Fast & Realistic OpenGL Event Displayer
Loic Quertenmont
[Full text] Proceedings of the Conference: XVII International Conference on Computing in high Energy and Nuclear Physics (CHEP09), March 21-27, 2009, Prague, Czech Republic
Contribution to proceedings. 15th May.
FROG: The Fast & Realistic OpenGL Event Displayer
Loic Quertenmont & Vincent Roberfroid
[Full text] FROG CMS Note (Public)
20 pages, 35 figures

Public experimental note. 27th April.
FROG: The Fast & Realistic OpenGL Event Displayer
Loic Quertenmont
[Full text] Proceedings of the Conference: XII Advanced Computing and Analysis Techniques in Physics Researsh, November 3-7, 2008, Erice, Italy
Contribution to proceedings. 27th January.
FROG: The Fast & Realistic OpenGL Event Displayer
Loic Quertenmont, Vincent Roberfroid
[Full text] 26 pages, 15 figures, Submitted, Software manual,
Associated web site : http://projects.hepforge.org/frog/

18th January.

2008

The 2008 CMS Computing, Software and Analysis Challenge
The CMS Collaboration
[Full text] CMS IN-2008/044. 90 pp G. Bruno and L. Quertenmont among the "actual" authors (~40)
Private experimental note. 11th December.
Silicon Strip Tracker Detector Performance with Cosmic Ray Data at the Tracker Integration Facility
J.-L. Bonnet, G. Bruno, B. De Callatay, B. Florins, A. Giammanco, G. Gregoire, Th. Keutgen, D. Kcira, V. Lemaitre, D. Michotte, O. Militaru, K. Piotrzkowski, L. Quertermont, V. Roberfroid, X. Rouby, D. Teyssier et al. (>100 authors)
[Full text] W. Adam et al., "Silicon Strip Tracker Detector Performance with Cosmic Ray Data at the Tracker Integration Facility", CMS NOTE-2008/032.
Public experimental note. 10th December.
Search for Heavy Stable Charged Particles with 100 pb-1 and 1 fb-1 in the CMS experiment
The CMS Collaboration
[Full text] The CMS Collaboration, "Search for Heavy Stable Charged Particles with 100 pb-1 and 1 fb-1 in the CMS experiment", CMS PAS EXO-08-003.
Physics Analysis Summary of an analysis that passed the full CMS approval procedure in april 2008. This document is public and, according to CMS rules, is signed by the whole CMS Collaboration. It is the summary of a much longer CMS analysis note signed by 15 CMS collaborators, among which G. Bruno (co-editor) and L. Quertenmont from UCL.

Public experimental note. 9th December.
Search for Heavy Stable Charged Particles at the LHC
Loic Quertenmont
[Full text] DIS08 Proceedings
Contribution to proceedings. 18th September.


[UCLouvain] - [SST] [IRMP] - [SC]
Contact : Jérôme de Favereau
Research
Job opportunities Postdoctoral Position on advanced analysis techniques applied to the CMS di-Higgs study
Post-doctoral positions in collider phenomenology and particle astrophysics
EOS be.h : 10 PhD positions