**WG Topics**

For the 2021 edition, we have set up the working groups described below. **In the spirit of the Les Houches PhysTev series, we expect a strong interplay and collaboration between the different groups and their subgroups.** The projects are to start in March/April 2021 and should be completed by the end of the year 2021.

Session 1

**Higgs Physics (SM aspects):**The main goal of this WG is to address the currently open theoretical and experimental issues relevant for the ultimate measurements of the Higgs boson properties at the LHC, and the prospects at future colliders. The WG will focus on the precise calculations of signal and background cross sections relevant for state-of-the-art measurements of the Higgs-boson properties. Improvements and new ideas in search strategies will also be discussed.**Techniques and calculations for SM phenomenology:**The topics to be discussed in this WG are related to theoretical predictions for SM processes and their phenomenology. The status and future prospects for state-of-the-art predictions at fixed-order ((N)NLO QCD, NLO EW, mixed QCD-QED effects) will be the main focus to be discussed. Aspects related to resummation at all-orders of large logarithmic contributions for specific observables, as well as modern developements in the extraction of PDFs and their interplay with computations at higher-order will also be covered in this WG.**Jet-substructure techniques:**The topics to be discussed in this WG are the theoretical developments of jet-substructure techniques and their phenomenological applications. Particularly from this edition, we foresee extensive discussions on the connection between these developments and Machine-Learning techniques.**Monte Carlo generators, Tools, Machine-Learning:**Topics to be covered in this WG have a large overlap with the other WGs: new approaches to implement higher-order corrections into Monte Carlo event generators will be discussed, as well as recently proposed ideas to improve the formal accuracy of Parton-Shower algorithms. From this edition, another topic on which emphasis will also be put are the opportunities opened up by the application of ML techniques to different aspects of Standard Model physics at the LHC.

Session 2

**Higgs Physics (BSM aspects):**This WG will cover aspects of Higgs-physics related to new physics. Constraints on new physics models will be addresses, either directly through the information the SM-like Higgs bosons provides for particle searches, or indirectly by its role in,*e.g*., flavour and low-energy physics, or its connection with Dark Matter.**BSM phenomenology at colliders:**In this WG, collider signatures of new physics models will be discussed together with other phenomenological aspects,*e.g.*, from Higgs, Dark Matter, or flavour physics. Particular attention will be given to potential signals at the forthcoming runs of the LHC.**High-precision low-energy probes:**This WG covers searches for new physics using novel probes based on high precision measurements in atoms and molecules.**Monte Carlo generators, Tools, Machine-Learning:**Topics to be covered in this WG have a large overlap with the other WGs. The emphasis will be on the implementation of new techniques to extract and implement new physics or set limits on generic models. Special focus will also be given to topics related to Machine-Learning techniques.

The meeting in Les Houches, **between June 7th and June 25th, 2021**, will be the central point of the Workshop. Here, in addition to the Working Group activities, a few lectures and review talks are planned. Participation to the Workshop is open to all. However, due to space limitation in Les Houches, attendance to the meeting is limited to 70 participants at any given point. Due to the overwhelming response of the past sessions, PhysTeV Les Houches 2021 is over a period of almost 3 weeks. Though we expect a few participants to be able to attend the meeting in its full duration, plans will be made so that a roughly equal number of participants cover the first or the second half of the meeting.

**In 2021 it is likely that there will be restrictions on the number of participants attending the Workshop in Les Houches.**