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PhD on di-Higgs search in ATLAS at LHC

This offer is available in the following languages:
Français - Anglais

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General information

Reference : UMR6533-DJABOU-001
Workplace : AUBIERE
Date of publication : Saturday, March 14, 2020
Scientific Responsible name : Djamel Boumediene
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

1. Scientific motivation

The Standard Model (SM), the theory that describes forces and matter, predicts the existence of the Higgs boson and six quarks, the heaviest being the Top quark. This particle plays a key role in the Standard Model. Its coupling with the Higgs boson is the most important. Its value has a significant impact on the functioning of the Higgs self coupling and on the stability of the Electroweak vacuum.
The discovery of the Higgs boson in 2012 opened the way to the study of its properties. The observation of its production and decay modes allows us to test the Higgs sector in the MS.
The observation of the associated production of a Top quark pair with a Higgs boson (ttH) was published in October 2018 by the ATLAS collaboration and in which our team played a significant role. This observation has been interpreted as an evidence for the Top Yukawa at the tree level. Today, we are moving towards another test in the Higgs sector: the test for the Higgs self-coupling. This coupling gives direct access to the Higgs potential itself and is considered a key measure of the HL-LHC (High Luminosity Large Hadron Collider) program.

2. Research project.

The thesis project focuses on the search for the production of Higgs boson pairs.
The first objective is to determine the experimental signatures that maximizes the sensitivity of the Higgs boson search. Data analysis will include optimization, background processes studies and statistical interpretation.

3. Bibliography.

- Searches for Higgs boson pair production in the hh → bbττ, γγWW ∗, γγbb, bbbb channels with the ATLAS detector (arXiv: 1509.04670)
- Why should we care about the top quark Yukawa coupling? Fedor Bezrukov, Mikhail Shaposhnikov J.Exp.Theor.Phys. 120 (2015) 3, 335-343; ZhETF 147 (2015) 3, 389 (arXiv: 1411.1923)

4. Qualification task.

During the first year, approximately 50% of the time will be spent on an activity related to the operation of the detector. This allows any new member of the ATLAS collaboration to be author. This qualification task is expected to be related to the High Granular Timing Detector (HGTD), a new ATLAS sub-detector for the HL-LHC phase.

Work Context

The Atlas@Clermont team is part of the Laboratoire de Physique de Clermont (LPC) which includes LHCb, ALICE, LSST and theoretical physics teams, as well as research teams in physics applied to health, environment and energy. The LPC is hosted by the University of Clermont Auvergne (UCA) and is part of the National Institute for Nuclear and Particle Physics (IN2P3), a division of the National Research Center (CNRS). About half of the 160 members of the LPC work in one of the technical departments (IT, mechanics, electronics and microelectronics) or in the administrative department.

The LPC is located in the suburbs of Clermont-Ferrand, a medium sized but dynamic city east of the Auvergne-Rhônes-Alpes region, 3:30 from CERN. The city is on the edge of the Auvergne Volcanoes Regional Park, recently registered on the UNESCO World Heritage List. Many cultural activities are offered and culminate each year in February with the International Short Film Festival (the largest festival in the world in this area). Clermont-Ferrand is also the heart of the Michelin company. The public transport network is efficient, the LPC in particular benefits from a tram stop in the immediate vicinity. The cost of living in Clermont-Ferrand is low compared to big cities like Lyon or Paris. Renting an apartment between 20 and 30 m2 in the city center near the tram costs around 400 euros per month.

The Atlas@Clermont team receives significant financial support each year from the CNRS / IN2P3, mainly covering travel costs (at CERN, workshops and conferences) and local IT costs. It offers the team a pleasant working environment (desktops and laptops), including a dedicated local batch cluster with 200 TB of disk storage.

The team is a founding member of the ATLAS collaboration and has always made a significant contribution to the hadronic calorimeter with scintillating tiles (TileCal), as well as to physics analyses, in particular in relation with the top quark (first thesis on this subject defended in 2002 ). The Atlas@Clermont team is also active in the upgrade phase 2 of the HL-LHC. It was involved for many years on TileCal and since 2018 on HGTD (High Granularity Timing Detector). For several years, the team has specialised in the search for a new physics with final state containing one or more top quarks (ttbar resonances, tbbar resonances) and in particular initiated in ATLAS in 2011 the search for events containing four quarks tops. Since 2013, the team has also contributed significantly to the search for the associated production of a Higgs boson with a pair of top quarks (ttH), finally observed in 2018.

It is not mandatory to speak French and free French lessons will be proposed. Good knowledge of English is required

Constraints and risks

Short stays at CERN and possibly abroad are expected.

Additional Information

Candidates must have:
- obtained a master's degree in particle physics before July 2019;
- a first research experience in particle physics of at least three months;
- a good knowledge of C ++ and if possible of the ROOT analysis software;
- a good level of spoken and written English;
- shown the ability to work in a team.

Applications must be submitted on this website (see "Apply" button at the top) with a curriculum vitae (2 pages maximum) and a cover letter.

In addition, two letters of recommendation must be sent directly to AtlasClermont.job@cern.ch

The offer will be closed as soon as an application has been accepted.

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