Jean-Marc Gérard
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
+32 10 47 2712
UCL member card
Special Relativity
Introduction to kinematics and dynamics in Minkowski space-time.
PHY1223 (22.5h + 15h; shared with J.Govaerts)
General Relativity
Introduction to Einstein's theory of gravity.
PHY1323 (30h + 15h)
Quantum field theory 1
Introduction to Quantum Electrodynamics.
PHY2120 (22.5h)
Fundamental interactions
Introduction to electroweak, strong and gravitational interactions.
PHY2121 (22.5h)
Strong interactions and symmetries
Introduction to perturbative QCD and to hadron physics.
PHY2223 (30h; shared with F.Maltoni)
Electroweak interactions
Introduction to the Standard Model.
PHY2224 (22.5h; shared with F.Maltoni)
People responsibilities
Former members
Vincent Boucher (IISN), Research scientist in CP3 from September 2003 to April 2013
Current position: Partner at B12 Consulting.

Mathieu Buchkremer (UCL), Visitor in CP3 from October 2010

Elvira Cerveró García (FRIA), PhD student in CP3 from October 2010

Alexandre De Spiegeleer, Master student in CP3

Céline Degrande (FNRS), PhD student in CP3 from September 2006 to September 2011
Current position: Postdoc at UIUC, USA.

François Goffinet (UCL), PhD student in CP3 from September 2003 to December 2008
Current position: Research engineer at NextWindow (Auckland - NZ).

Michel Herquet (IISN), PhD student in CP3 from October 2003 to September 2008
Current position: Partner at B12 Consulting and at Novapta. Formerly: McKinsey & Company, Postdoc at NIKHEF (NL).

Noël Janssens, Master student in CP3

Nan Li, Postdoc in CP3 from November 2008 to November 2010

Philippe Mertens (UCL), PhD student in CP3 from January 2008

Maëlle Richard, Master student in CP3 from October 2009
Current position: Physics teacher.

Christopher Smith, PhD student in CP3

Sylvain Vanneste, Master student in CP3 from September 2015

Research statement
My interests cover the phenomenology of the four fundamental interactions.
Strong interactions
The use of an effective theory for Quantum Chromo Dynamics in the large-N limit to cast a new glance on:
-the U(1) problem and the resulting strong CP-violation;
-the non-perturbative effects on Formula: 0 and Formula: 1hadronic decays.
Electroweak interactions
The use of Quantum Flavor Dynamics to get theoretical constraints on:
-the fermion mixings and the resulting weak CP-violation;
-the boson mass spectrum in multi-Higgs doublet models.
Gravitational interactions
The use of equivalence principles to test relativistic theories of gravity:
-around the Sun;
-in the early Universe.
I am involved in the following research directions:

CP and chiral symmetry in K physics.

Study anomalous effect on the Formula: 0 energy distribution and try to extract the Formula: 1 parameter Formula: 2 from experimental data.

On the unification of gauge coupling constants

In the standard model version of the grand unified theory different gauge couplings intend to, but do not, meet at some higher scale. Here we will look for some better ways for the unification of the gauge coupling constants.

Scalar-tensor theories of gravitation

The strong equivalence principle (SEP) does not hold anymore in various extensions of General Relativity. Its violations can be revealed by the non-universality of free-falling for compact objects and we have developed a generic and effective way to test the SEP in the Cosmic Microwave Background (CMB). A violation of the SEP indeed alters the amplitude of the acoustic oscillations in the primeval plasma. Using the WMAP data, we have contrained a possible SEP violation for the baryons.

Our interests are also focused on the scalar-tensor theories of gravitation and their cosmologies. In a more specific way, we are currently studying a model where the scalar sector is conformally invariant. The effective fluid related to the non-minimally coupled scalar field differs from the other cosmological fluids of radiation by its very particular anisotropic pressure and we are studying its impact on the CMB anisotropies by modifying the CAMB code.

Tensions in flavor physics and two Higgs doublet models

Study of the tensions observed between the K and the B meson systems and their implications for scalar-mediated flavor changing currents in the framework of two Higgs doublet models (2HDM).

Past projects
Hide past projects.

I am involved in the following research directions:

Formula: 0 in the SM and beyond.

The relative strengths of Formula: 0, Formula: 1 and Formula: 2 processes provide a powerfull tool to probe new physics (NP). Focusing on the Formula: 3 transition we indentify the most promising observables to look for NP, improve their SM predictions (by improving calculations and using recent experimental data) and provide a NP analysis.

External collaborators: Christopher Smith (Université Lyon 1).

Custodial symmetry and top mass

We try to lower the bound on the first new physics states in the toy model proposed in arxiv:1009.2477 by adding extra custodial symmetry breaking term that are also require to obtain a realistic mass spectrum. The model is based on custodial and L-R symmetry in order to protect the Zbbar coupling.

Effective theory in the SM in ChPT

Computation of one loop corrections in ChPT for the nonet of pseudoscalars mesons. In particular, corrections to the Formula: 0 mixing angle and to their masses and also to the vev of Formula: 1. The last quantity could contribute to the neutron EDM.

Observability of a minimal extension of the scalar sectror: 2HDM at the LHC

The goal of this work is to explore the phenomenology of a two Higgs doublet model with a custodial symmetry. It provides topologies that are unusual in the models usually considered in the literature. Notably, it opens the possibility of having an inverted mass spectrum with respect to MSSM with the lightest Higges being a pseudo-scalar and an heavier triplet of charged and neutral higgses.

External collaborators: Simon de Visscher (Zurich university).

Weak and strong CP violations

Weak interaction contributions to the strong $\theta$ parameter are revisited in the frame of a large-$N_c$ Chiral Perturbation Theory. Focusing on the hadronic $\eta^{(\prime)}\rightarrow \pi \pi$ amplitudes, we express these second-order corrections in terms of the CP-violating parameter in $K \rightarrow \pi \pi$ decays.

Publications in CP3
All my publications on Inspire


Final State Interactions in $K opipi$ Decays: $Delta I=1/2$ Rule vs. $ arepsilon^prime/ arepsilon$
Buras, Andrzej J. and Gerard, Jean-Marc
[Abstract] [PDF] [Journal]
15th March.


Upper bounds on ε′/ε parameters B$_{6}^{(1/2)}$ and B$_{8}^{(3/2)}$ from large N QCD and other news
Buras, Andrzej J. and Gérard, Jean-Marc
[Abstract] [PDF] [Journal]
Refereed paper. 30th June.


Large N Approach to Kaon Decays and Mixing 28 Years Later: $\Delta=1/2$ Rule, $\hat{B}_{K}$ and $\Delta M_{K}$
A. J. Buras, J. M. Gérard and W. A. Bardeen
[Abstract] [PDF] [Journal] Published in Eur.Phys.J. C74 (2014) 5, 2871
Refereed paper. 2nd January.


Ultimate survival in anomalous $psi(2S)$ decays
Gerard, Jean-Marc and Martini, Antony
[Abstract] [PDF] [Journal] Phys.Lett. B730 (2014) 264-266
Refereed paper. 11th December.


Three-generation baryon and lepton number violation at the LHC
Gauthier Durieux, Jean-Marc Gérard, Fabio Maltoni and Christopher Smith
[Abstract] [PDF] [Journal] Published in Phys.Lett.B 721 (2013) 82
Refereed paper. 24th October.
Weakly-induced strong CP-violation
J. M. Gerard and P. Mertens
[Abstract] [PDF] [Journal] Physics Letters B 716 (2012), pp. 316-321.
Refereed paper. 5th June.
Probing top-Higgs non-standard interactions at the LHC
Degrande, C. and Gerard, J. M. and Grojean, C. and Maltoni, F. and Servant, G.
[Abstract] [PDF] [Journal]
Refereed paper. 8th May.
Closing in on a perturbative fourth generation
Mathieu Buchkremer, Jean-Marc Gérard and Fabio Maltoni
[Abstract] [PDF] [Journal] 23 pages, 6 figures. Published in Journal of High Energy Physics as JHEP 06 (2012) 135.
Refereed paper. 25th April.
Flavor Mixing Democracy and Minimal CP Violation
Jean-Marc Gérard, Zhi-zhong Xing
[Abstract] [PDF] [Journal] Published in Phys. Lett. B 713 (2012) 29-34
Refereed paper. 6th March.
Minimal violation of flavour and custodial symmetries in a vectophobic Two-Higgs-Doublet-Model
Cervero, Elvira and Gerard, Jean-Marc
[Abstract] [PDF] [Journal] Published in Physics Letters B 712 (2012), pp. 255-260
Refereed paper. 9th February.
De l'éclipse totale du Soleil à l'énigme de l'énergie sombre
Jean-Marc Gérard
[Full text] Published in Revue des Questions Scientifiques, 183 (2012) 145-168
Refereed paper. 10th January.
Role of Kaon Physics, present - future
Jean-Marc Gérard and Paolo Valente
[Full text] Comptes Rendus - Physique 13 (2012) 127-132 (Académie des Sciences, Paris).
Refereed paper. 5th January.


Baryon number violation at the LHC: the top option
Dong, Zhe and Durieux, Gauthier and Gerard, Jean-Marc and Han, Tao and Maltoni, Fabio
[Abstract] [PDF] [Journal] Published in Phys.Rev. D85 (2012) 016006.
Refereed paper. 19th July.
An effective approach to same sign top pair production at the LHC and the forward-backward asymmetry at the Tevatron
Degrande, Celine and Gerard, Jean-Marc and Grojean, Christophe and Maltoni, Fabio and Servant, Geraldine
[Abstract] [PDF] [Journal] Published in Physics Letters B.
Refereed paper. 11th April.


An upper bound on the Kaon B-parameter and CP-asymmetry
Jean-Marc Gérard
[Abstract] [PDF] [Journal] JHEP 1102: 075, 2011
Refereed paper. 8th December.
Non-resonant New Physics in Top Pair Production at Hadron Colliders
Céline Degrande, Jean-Marc Gérard, Christophe Grojean, Fabio Maltoni and Géraldine Servant
[Abstract] [PDF] [Journal] Published in JHEP03(2011)125
Refereed paper. 27th September.
Cosmological perturbation in f(R,G) theories with a perfect fluid.
Antonio De Felice, Jean-Marc Gerard and Teruaki Suyama
[Abstract] [PDF] [Journal] Phys. Rev. D82 (2010) 063526
Refereed paper. 14th May.


Cosmological perturbations of a perfect fluid and noncommutative variables
Antonio De Felice, Jean-Marc Gerard and Teruaki Suyama
[Abstract] [PDF] [Journal] Published in Physical Review D81 (2010) 063527
Refereed paper. 25th August.
Unconventional phenomenology of a minimal two-Higgs-doublet model
Simon de Visscher, Jean-Marc Gerard, Michel Herquet, Vincent Lemaitre, Fabio Maltoni
[Abstract] [PDF] [Journal] Published in JHEP08(2009)042.
Refereed paper. 3rd April.
A theoretical determination of the eta-eta' mixing
C. Degrande and J.-M. Gerard
[Abstract] [PDF] [Journal] 10 pages, 2 figures. Published in JHEP05(2009)043
Refereed paper. 19th January.


Mass Issues in Fundamental Interactions
Jean-Marc Gérard
[Abstract] [PDF] Based on three lectures given at the 2008 European School of High-Energy Physics (Herbeumont, 8 June-21 June 2008)
Contribution to proceedings. 5th November.
Collider aspects of flavour physics at high Q
del Aguila, F. and others
[Abstract] [PDF] [Journal] Report of Working Group 1 of the CERN Workshop Flavor in the Era of the LHC. Published in Eur.Phys.J.C57:183-308,2008.
Refereed paper. 14th January.


A Twisted Custodial Symmetry in the Two-Higgs-Doublet Model
J.-M. Gérard, M. Herquet
[Abstract] [PDF] [Journal] Published in Phys. Rev. Lett. 98, 251802 (2007)
Refereed paper. 5th March.


Tracking down penguins at the poles
Gerard, Jean-Marc an Smith, Christopher and Trine, Stephanie
[Abstract] [PDF] Talk given at 41st Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Aosta Valley, Italy, 11-18 Mar 2006
Contribution to proceedings. 14th May.
Anomalous enhancement of a penguin hadronic matrix element in B->K eta'
J.-M. Gerard and E. Kou
[Abstract] [PDF] [Journal] Pblished in Phys.Rev.Lett.97 (2006) 261804
Refereed paper. 21st September.
The strong equivalence principle from a gravitational gauge structure
Jean-Marc Gerard
[Abstract] [PDF] [Journal] Published in Class.Quantum Grav. 24 (2007) 1867-1877
Refereed paper. 5th July.
Is Vtb=1?
J. Alwall, R. Frederix, J.-M.Gerard, A. Giammanco, M. Herquet, S. Kalinin, E. Kou, V. Lemaitre, F. Maltoni
[Abstract] [PDF] [Journal] Published in Eur.Phys.J.C.49 (2007) 791
Refereed paper. 29th June.


A new look at an old mass relation
Gerard, J. -M. and Goffinet, F. and Herquet, M.
[Abstract] [PDF] [Journal] Published in Phys. Lett. B633( 2006) 563-566
Refereed paper. 21st October.
Radiative kaon decays and the penguin contribution to the Delta(I) = 1/2 rule
Gerard, Jean-Marc and Smith, Christopher and Trine, Stephanie
[Abstract] [PDF] [Journal] Published in Nucl. Phys. B730 (2005) 1-36
Refereed paper. 17th August.
Survival before annihilation in Psi-prime decays
Artoisenet, P. and Gerard, J. -M. and Weyers, J.
[Abstract] [PDF] [Journal] Published in Phys. Lett. B628 (2005) 211-214
Refereed paper. 30th June.

[UCLouvain] - [SST] [IRMP] - [SC]
Contact : Jérôme de Favereau
Job opportunities Postdoctoral position: Search for Hidden Sector mediations at NA62 experiment
EOS be.h : 10 PhD positions
Postdoctoral position: Data Analysis and GTK operation for NA62 experiment
Postodoctoral position in precision and BSM Phenomenology
Postdoctoral Position in Precision Computations for the LHC