Olivier Mattelaer
Research scientist. Funding: UCL.
Member since September 2005
Centre for Cosmology, Particle Physics and Phenomenology - CP3
Université catholique de Louvain
2, Chemin du Cyclotron - Box L7.01.05
B-1348 Louvain-la-Neuve
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Automated Computation of One-Loop Amplitudes
freely accessible from this link:
I am involved in the following research directions:

Loop-induced processes in the SM and Beyond

Automation within MadGraph5_aMLO and phenomenological studies of loop-induced processes for the LHC


Monte Carlo development.

External collaborators: Benjamin Fuks, Kentarou Mawatari, Kaoru Hagiwara, Tim Stelzer, Stefano Frixione, Marco Zaro, Rikkert Frederix, Valentin Hirschi, Paolo Torrielli, Johan Alwall, Hua-Sheng Shao, Mihailo Backovic,...

Past projects
Hide past projects.

I am involved in the following research directions:

Advanced Techniques for Fast Simulation and Data Analysis in High Energy Physics (ASAP)

The discovery of the 125GeV Higgs boson by the LHC experiments has finally opened a new era in the exploration of the TeV scale. The physics programs of CMS and ATLAS aim far beyond the simple discovery, and vigorously pursue the full characterization of the newly discovered state and the full exploration of the TeV scale in search of new phenomena. A key lesson drawn from first two years of LHC running is that most probably first discoveries and then identification of new states/interactions will not be easy. On the one hand, model-independent searches in simple topologies such as single/multi lepton at high transverse momenta have not shown any hint of new physics so far. On the other, topologies with jets and/or missing transverse energies, much more challenging experimentally, do strongly depend on the underlying theoretical models so that efficiently identifying signal enhanced regions of the phase space is quite involved. In this context, multi-variate techniques have become more and more central in the analysis of data from hadron collider experiments, to maximally exploit the information available on the signal and on the backgrounds. Amongst the most advanced techniques and certainly the most powerful one from the theoretical point of view, the so called matrix element method stands out. The main goal of this proposal is to advance the use and the scope of the matrix-element method so to significantly extend the range of physics applications at the LHC to the search of new physics. First we aim at providing the experimental HEP community with complete and automatic simulation tools, such as MadWeight/MoMEMta and Delphes, that overcome the technical limitations of the method. Second we propose to test and apply the new tools to current analyses in signatures that involve final state leptons and b-jets. Finally, we explore new and original applications of the method to both model-dependent or model-independent searches of new physics at the LHC.

External collaborators: CMS collaboration.


Create a code to create automatically HELAS routine in various format from the Feynman Rules.

Automatic Matrix Element method and associated analyses techniques

Madweight is a algorithm to automatically reweight experimental events with the squared matrix element, and therefore provides the required computation techniques for a practical application of the matrix element method.

We also study the usefullness of MadWeight to estimate differential cross-section Formula: 0 via the marginal distributions of the the experimental weights Formula: 1.

External collaborators: Pierre Artoisenet (Ohio state university).

Deformation of quantum dynamics in Phase Space

In this project, we study a deformation of the path integral introducing a new time scale. This deformation is inspired by Klauder's path integral construction using a Riemannian metric on phase space. The introduction of this new time scale leads to a complex Landau problem, non commutative geometry and non unitarity effects.

Publications in CP3
All my publications on Inspire


Event generation for beam dump experiments
L. Buonocore, C. Frugiuele, F. Maltoni, O. Mattelaer, F. Tramontano
to be submitted
Refereed paper. 3rd December.
A Heavy Metal Path to New Physics
Drewes, Marco and Giammanco, Andrea and Hajer, Jan and Lucente, Michele and Mattelaer, Olivier
[Abstract] [PDF]
Refereed paper. 22nd October.
Automated computation of one-loop amplitudes
C. Degrande, V. Hirschi, O. Mattelaer
[Full text] Review paper requested by AR Nuclear and Particle Science
(reviewed by Michael Peskin)

9th May.
MadDM v.3.0: a Comprehensive Tool for Dark Matter Studies
F. Ambrogi, C. Arina, M. Backovic, J. Heisig, F. Maltoni, L. Mantani, O. Mattelaer, G. Mohlabeng
[Abstract] [PDF] to be submitted to Phys. Dark. Univ.
Refereed paper. 30th March.


Reconstructing the invisible with matrix elements
Ferreira de Lima, Danilo Enoque and Mattelaer, Olivier and Spannowsky, Michael
[Abstract] [PDF] [Journal] to be submitted to PRL
Refereed paper. 8th December.
Circular polarisation: a new probe of dark matter and neutrinos in the sky
Bœhm, Céline and Degrande, Céline and Mattelaer, Olivier and Vincent, Aaron C.
[Abstract] [PDF] [Journal] Published in JCAP 1705 (2017) no.05, 043
Refereed paper. 9th January.


Automated Neutrino Jet and Top Jet Predictions at Next-to-Leading-Order with Parton Shower Matching in Effective Left-Right Symmetric Models
Mattelaer, Olivier and Mitra, Manimala and Ruiz, Richard
[Abstract] [PDF] details will be uploaded when the paper will appear on arxiv
Refereed paper. 26th October.


The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
Alwall, J. and Frederix, R. and Frixione, S. and Hirschi, V. and Maltoni, F. and others
[Abstract] [PDF] [Journal] to be submitted
Refereed paper. 4th April.
Computing decay rates for new physics theories with FeynRules and MadGraph5/aMLO
Alwall, Johan and Duhr, Claude and Fuks, Benjamin and Mattelaer, Olivier and Ozturk, Deniz Gizem and others
[Abstract] [PDF] [Journal] to be submitted
Refereed paper. 3rd February.
Higgs pair production at the LHC with NLO and parton-shower effects
Frederix, R. and Frixione, S. and Hirschi, V. and Maltoni, F. and Mattelaer, O. and others
[Abstract] [PDF] [Journal] submitted
Refereed paper. 28th January.


Unravelling tth via the matrix element method
Artoisenet, Pierre and de Aquino, Priscila and Maltoni, Fabio and Mattelaer, Olivier
[Abstract] [PDF] [Journal] refereed paper.
Refereed paper. 13th April.


Determination of differential cross sections from ttbar fully leptonic, using the matrix element method
A. Pin and O. Mattelaer
[Journal] [Full text] Published in Il Nuovo Cimento C, Top 2011 Conference Proceedings
Contribution to proceedings. 6th June.
Effective Field Theory: A Modern Approach to Anomalous Couplings
Degrande, Celine and others
[Abstract] [PDF] [Journal] Submitted to PRD
Refereed paper. 18th May.


ALOHA: Automatic Libraries Of Helicity Amplitudes for Feynman diagram computations
Priscila de Aquino, William Link, Fabio Maltoni, Olivier Mattelaer, Tim Stelzer
[Abstract] [PDF] [Journal] To be submitted to Computer Physics Communications.
Refereed paper. 3rd August.
UFO - The Universal FeynRules Output
Celine Degrande, Claude Duhr, Benjamin Fuks, David Grellscheid, Olivier Mattelaer, Thomas Reiter
[Abstract] [PDF] [Journal] Published in CPC
Refereed paper. 22nd July.
MadGraph 5 : Going Beyond
Alwall, Johan and Herquet, Michel and Maltoni, Fabio and Mattelaer, Olivier and Stelzer, Tim
[Abstract] [PDF] [Journal] Published in JHEP06(2011)128
Refereed paper. 16th April.


The Matrix Element Method and QCD Radiation
Alwall, J. and Freitas, A. and Mattelaer, O.
[Abstract] [PDF] [Journal] Published in PhysRevD.83.074010
Refereed paper. 7th October.
Automation of the matrix element reweighting method
Pierre Artoisenet, Vincent Lemaître, Fabio Maltoni, Olivier Mattelaer
[Abstract] [PDF] [Journal] Published in JHEP12(2010)068
Refereed paper. 19th July.


Measuring Sparticles with the Matrix Element
Alwall, Johan and Freitas, Ayres and Mattelaer, Olivier
[Abstract] [PDF] [Journal] Proceedings of Conference SUSY09
Contribution to proceedings. 15th October.
The Klauder-Daubechies Construction of the Phase Space Path Integral and the Harmonic Oscillator
Jan Govaerts, Calvin Matondo Bwayi and Olivier Mattelaer
[Abstract] [PDF] [Journal] Published in J. Phys. A: Math. Theor. 42 (2009) 445304 (20 pages)
Highlighted on IoP Select:

Refereed paper. 6th August.


A Deformation of Quantum Dynamics through the Phase Space Path Integral
Jan Govaerts and Olivier Mattelaer
[Abstract] [PDF] [Full text] Proc. Fifth International Workshop on Contemporary Problems in Mathematical Physics, October 27th-November 2nd, 2007, Cotonou, Republic of Benin, Eds. J. Govaerts and M. N. Hounkonnou (International Chair in Mathematical Physics and Applications, ICMPA-UNESCO Chair, Cotonou, Republic of Benin, 2008), pp. 170-186, refereed contribution.
Contribution to proceedings. 2nd December.
MadWeight: automatic event reweighting with matrix elements
Pierre Artoisenet, Olivier Mattelaer
[Full text] Charged Higgs 2008 (Uppsala) presented by O. Mattelaer
Contribution to proceedings. 28th November.
New Developments in MadGraph/MadEvent
J. Alwall, P. Artoisenet, S. de Visscher, C. Duhr, R. Frederix, M. Herquet, O. Mattelaer
[Abstract] [PDF] [Journal] SUSY08 Proceedings (plenary talk by Johan Alwall)
Contribution to proceedings. 15th September.

[UCLouvain] - [SST] [IRMP] - [SC]
Contact : Jérôme de Favereau
Job opportunities Post-doctoral positions in BSM phenomenology at colliders and in astrophysics
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