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Proposals for Master or PhD thesis at LPTHE
Internship/PhD in theoretical high energy physics
Advisor: Karim Benakli
We are looking for a Master-2 student with a background in high energy theoretical physics interested in one of the following three topics, to be discussed to agree on a choice with the student:
1) Supersymmetry breaking models: supersymmetry, a symmetry with several virtues for theories beyond the Standard Model, is not observed experimentally, so it must be broken if it plays a role in nature.
2) The weak gravity conjecture: this conjecture states that for any abelian gauge theory, there exists a state for which the gravitational force (Newton) is weaker than the gauge interaction (Coulomb).
3) The study of the equations of motion describing the propagation of particles in non-trivial media. In particular, for particles with spin > 1, the description of the propagation of longitudinal helicity modes presents interesting properties and requires a particular analysis.
A Ph.D. in theoretical high-energy physics is also possible on similar topics, subject to the usual condition of successful application to the Doctoral School.
Contact: Karim Benakli by e-mail at kbenakli_AT_lpthe.jussieu.fr
Internship/PhD in Dark Matter theory and phenomenology
Advisor: Marco Cirelli
About 85% of the matter in the Universe is in the form of an unknown substance dubbed Dark Matter (DM). While some of its general properties are known, its actual nature is still undetermined. The most popular hypothesis is that it consists of a new, yet-to-be-discovered elementary particle. One of the possible strategies to investigate it is via the so-called Indirect Detection (ID): studying the possible excesses in cosmic rays that could produced by the annihilations (or decays) of DM particles in the galactic halo, and comparing them with the theoretical predictions from particle physics models.
Within this broad context, the proposed Master 2 internship (and the possible ensuing PhD project) will proceed in different directions: X-rays, velocity-dependent annihilations, primordial black holes constraints, synchrotron bounds, purely gravitational effects... (to be decided according to the interests and the opportunities).
Following the typical course, after the Master 2 internship lasting a few months during Spring 2024 and subject to mutual agreement, the student can then apply for a PhD fellowship (from EDPIF or from other sources) and, if successful, start the PhD in Fall 2024, for a duration of 3 years.
Application procedure: Candidates should send by email to marco.cirelli_AT_gmail.com: i. their CV, ii. a transcript of their academic records, iii. a short description of their interests (optional, and in any case no longer than 1 page). iv. They should also arrange for 1 or 2 short letters of recommendation to be sent to the same address, by scientists familiar with their studies and academic record.
Applications are preferred within December 31st, 2023, but will be considered afterwards if the position is not filled. Short-listed candidates will be invited for a meeting, either in person or remotely.
Internship/PhD on Precision predictions for four-top production at the LHC
Advisors: Benjamin Fuks and Hua-Sheng Shao
The Standard Model of particle physics is an extremely successful theory whose predictions match data to an excellent extent. Despite this success, the current experimental status reveals several of its conceptual and practical limitations, like the absence of a candidate for dark matter, the hierarchy problem or the problematics of neutrino masses. The Standard Model is therefore acknowledged as an effective theory that should originate from a more fundamental one yet to be discovered, and new phenomena are expected at energies well below the Planck scale. One interesting avenue in the searches for new physics relies on probes involving the comparison of precision theoretical predictions to accurate experimental measurements.
By far and large, this currently means making use of matrix elements computed to (at least) the next-to-leading-order accuracy and possibly matched with the resummation of threshold logarithms. The latter consists of an attempt to quantify the effects of a well-defined set of corrections to all orders of perturbation theory, with the aim of reducing the theory error bars (so that meaningful comparisons with experimental data could be achieved). In recent years, we have developed a numerical program achieving resummed predictions for four-top production at hadron colliders. The choice to focus on such a process is driven by the fact that among all measurements to be made at the currently on-going LHC Run 3, those related to four-top production will be performed for the first time with enough precision for being compared with theoretical predictions. It is therefore critical to provide precise theoretical predictions. The proposed internship aims to make use of the program that has been developed at LPTHE, understand the underlying concepts (inherent to the theory of the strong interaction, i.e. QCD) and improve its efficiency so that it could be shared with the high-energy physics community as a whole.
After the M2 internship that is expected to last a few months in Spring 2024 and subject to mutual agreement, the candidate will then apply for a PhD fellowship (from EDPIF or other sources) to start in Fall 2024 and for a duration of three years.
Application procedure
Candidates familiar with computer programming languages like C/C++ are particularly encouraged to apply.
Candidates should send by email to fuks_AT_lpthe.jussieu.fr and huasheng.shao_AT_lpthe.jussieu.fr their CV, a transcript of their academic records (M1 + L3 + existing M2 results if any) and a short motivation letter (optional and no longer than one page). They should also arrange for one or two letters of recommendation to be sent to the same addresses, by scientists familiar with their studies and academic records.
Applications are preferred within 31 st December 2023, but will be considered afterwards if the position is not filled. Short-listed candidates will be invited for a meeting, either in person or remotely.
