Contact
Name
Agni Bethani

Position
Academic staff

Email
agni.bethani@uclouvain.be

Address
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
Belgium

Office
E.260

UCL member card
http://www.uclouvain.be/agni.bethani
People responsibilities
PhD students
Francisco Casalinho (UCL-FSR) (member since November 2023)
This project is to study Higgs pair production in the bbtautau final state at CMS. The objectives of this study are: to measure the Higgs self-coupling constant, explore anomalous values of the Higgs couplings and new Higgs couplings using effective field theory parameterisation and study the Higgs pair production associated with a vector boson.
Projects
Research directions:
Data analysis in HEP, astroparticle and GW experiments
Detector commissioning, operation and data processing
Phenomenology of elementary particles
Research and development of new detectors

Experiments and collaborations:
CMS

Active projects
Advanced Multi-Variate Analysis for New Physics Searches at the LHC
Agni Bethani, Christophe Delaere, Andrea Giammanco, Vincent Lemaitre, Fabio Maltoni

With the 2012 discovery of the Higgs boson at the Large Hadron Collider, LHC, the Standard Model of particle physics has been completed, emerging as a most successful description of matter at the smallest distance scales. But as is always the case, the observation of this particle has also heralded the dawn of a new era in the field: particle physics is now turning to the mysteries posed by the presence of dark matter in the universe, as well as the very existence of the Higgs. The upcoming run of the LHC at 13 TeV will probe possible answers to both issues, providing detailed measurements of the properties of the Higgs and extending significantly the sensitivity to new phenomena.

Since the LHC is the only accelerator currently exploring the energy frontier, it is imperative that the analyses of the collected data use the most powerful possible techniques. In recent years several analyses have utilized multi-variate analysis techniques, obtaining higher sensitivity; yet there is ample room for further improvement. With our program we will import and specialize the most powerful advanced statistical learning techniques to data analyses at the LHC, with the objective of maximizing the chance of new physics discoveries.

We have been part of AMVA4NewPhysics, a network of European institutions whose goal is to foster the development and exploitation of Advanced Multi-Variate Analysis for New Physics searches. The network offered between 2015 and 2019 extensive training in both physics and advanced analysis techniques to graduate students, focusing on providing them with the know-how and the experience to boost their career prospects in and outside academia. The network develops ties with non-academic partners for the creation of interdisciplinary software tools, allowing a successful knowledge transfer in both directions. The network studies innovative techniques and identifies their suitability to problems encountered in searches for new physics at the LHC and detailed studies of the Higgs boson sector.

External collaborators: University of Oxford, INFN, University of Padova, Université Blaise Pascal, LIP, IASA, CERN, UCI, EPFL, B12 Consulting, SDG Consulting, Yandex, MathWorks.
Search for Higgs boson(s) in CMS at the LHC in the llbb topology
Agni Bethani, Jérôme de Favereau, Christophe Delaere, Vincent Lemaitre

Search for Higgs boson(s) within the Standard Model and beyond and also withing a minimal extension of the scalar sector (2HDM).

The final state under study is a Z decaying into a lepton pair associated with two b-jets. This topology is sensitive to a light SM Higgs via the associate ZH production, as well as a middle mass range SM Higgs boson via the inclusive Higgs production followed by its decay into ZZ with one Z decaying into a lepton pair and the other into bbar.

It is also very sensitive to the production of a non standard heavy Higgs boson decaying into Z plus A (pseudo scalar Higgs boson).

Similar selection (but outside of the Z window) is also sensitive to H->aa->llbb, with "a" a generic light scalar.

External collaborators: CMS collaboration.
Search for nonresonant Higgs boson pair production in the llbb+MET final state
Agni Bethani, Christophe Delaere, Vincent Lemaitre, Fabio Maltoni

The discovery of a Higgs boson (H) by the ATLAS and CMS experiments fixes the value of the self-coupling λ in the scalar potential whose form is determined by the symmetries of the Standard Model and the requirement of renormalisability. Higgs boson pair production is sensitive to the self-coupling and will play a major role in investigating the scalar potential structure.

This project consists in a search for nonresonant Higgs boson pair production via gluon fusion in the final state with two leptons, two b jets and missing transvere energy – gg → H(bb) H(WW) asking for the leptonic decay of the W's. The analysis is conducted in close collaboration with phenomenologists to ensure the approach is theoretically sound and future-proof.
Search for resonant Higgs pair production in the llbb+MET final state
Agni Bethani, Christophe Delaere, Vincent Lemaitre

The recent discovery of a scalar boson compatible with the Standard Model (SM) Higgs boson opened new windows to look for physics beyond the SM (BSM). An example of newly accessible phenomenology is the production of resonances decaying into two SM Higgs bosons (h) predicted by several theory families such as additional Higgs singlet/doublet or warped extra dimension.

This project consists in a search for spin-0 or spin-2 resonances produced via gluon fusion in the final state with two leptons, two b-jets and missing transverse energy – gg → X → h(bb) h(WW) asking for the leptonic decay of the W's. In particular, we are probing a mass range between 260 GeV and 900 GeV.
Study and optimization of b-tagging performances in CMS
Agni Bethani, Christophe Delaere

We are involved in the activities of the btag POG (performance object group) of CMS, in release and data validation and purity measurement. We are also interested in btagging in special cases like for colinear b-jets. Furthermore, we are involved in the re-optimization and improvement of the Combined Secondary Vertex (CSV) tagger for the 2012 analyses.

External collaborators: Strasbourg CMS group, CMS collaboration.
The CMS silicon strip tracker upgrade
Anna Benecke, Agni Bethani, Laurent Bruniaux, Jérôme de Favereau, Christophe Delaere, Pavel Demin, Paul Malek, Nicolas Szilasi

Development of the "phase II" upgrade for the CMS silicon strip stracker.

More precisely, we are involved in the development of the uTCA-based DAQ system and in the test/validation of the first prototype modules. We take active part to the various test-beam campaigns (CERN, DESY, ...)

This activity will potentially make use of the cyclotron of UCL, the probe stations and the SYCOC setup (SYstem de mesure de COllection de Charge) to test the response to laser light, radioactive sources and beams.

The final goal is to take a leading role in the construction of part of the CMS Phase-II tracker.

External collaborators: CRC and CMS collaboration.
Publications in IRMP
All my publications on Inspire

Number of publications as IRMP member: 1

2022

CP3-22-38: Strategies and performance of the CMS silicon tracker alignment during LHC Run~2
Tumasyan, Armen and others

[Abstract] [PDF] [Local file] [Journal] [Dial] [Full text]
Published in Nucl. Instrum. Meth. A
Refereed paper. August 12.