**New strong dynamics**

### New strong dynamics beyond the standard model, Fall 2017

Major experiments are underway and planned around the world to search for new physics beyond the standard model (BSM). They are accompanied by comparable theoretical efforts to gain insight into issues including the stabilization of the electroweak scale and the nature of dark matter. The possibility that such new physics may be strongly coupled presents both challenges for theoretical analyses as well as opportunities to advance our understanding of nature.

This course introduced some of the most prominent proposed extensions of the standard model in which new strong dynamics play a central role. After presenting the basic conceptual frameworks for both composite Higgs models and composite dark matter models, we reviewed current phenomenological constraints and the prospects for future discoveries. We also considered the role of lattice gauge theory as a means to obtain non-perturbative predictions for these strongly interacting systems.

### Learning outcome

Upon completing this course, students are able to:

- Explain the structure of representative composite Higgs and composite dark matter models.
- Interpret direct and indirect experimental constraints on these models.
- Judge the motivations and prospects of model-building proposals in the current literature.
- Describe the potential contributions of lattice calculations to investigate new strong dynamics, and their limitations.

### Schedule

We met from 10:15 to 12 on the following Thursdays and Tuesdays:

**2 November:** Lecture notes

Course overview; Motivations for BSM in general and new strong dynamics in particular; Electroweak symmetry breaking (EWSB) via QCD-like new strong dynamics and resulting challenges

**9 November:** Lecture notes

EW precision observables (*S* parameter); PNGB composite Higgs motivation; "Minimal Composite Higgs Model" (CCWZ construction and decoupling limit); Radiative EWSB from vacuum misalignment

**16 November:** Lecture notes

Vacuum misalignment via partial compositeness; Flavor physics from partial compositeness; "Minimal" UV completions; Partially composite UV completions

**21 November:** Lecture notes

Composite Higgs phenomenology: Direct searches for heavy resonances; Indirect constraints from Higgs couplings, EW precision observables, and flavor physics

**28 November:** Lecture notes

Lattice gauge theory: Space-time discretization and continuum limit; Lattice actions; Wilson vs. staggered vs. domain wall lattice fermions; Application to spectra of composite Higgs models; Supplement: Near conformality and anomalous dimensions

**5 December:** Lecture notes

Lattice gauge theory application to low-energy coefficients of composite Higgs EFTs; Evidence for dark matter (DM); Resulting features of DM; Motivations for composite DM

**12 December:** Lecture notes

Production of DM in early universe; Ongoing searches for DM (direct detection, indirect detection, collider production); Overview of composite DM candidates; Representative models of mesonic composite DM

**19 December:** Lecture notes

Representative models of non-mesonic composite DM; Stealth Dark Matter model; Lattice gauge theory applications to composite DM (direct detection and collider searches); Supplement: Indirect detection and gravitational waves

### Resources

The assumed background is exposure to quantum field theory and the standard model of particle physics (including group theory, gauge theory and spontaneous symmetry breaking), at the level of standard textbooks such as those by Peskin and Schroeder, Srednicki, or Schwartz. However, even without this experience students should be able to take away the main qualitative points of the course and fill in more details through subsequent studies.

Useful references on composite Higgs and composite dark matter physics include:

- Giuliano Panico and Andrea Wulzer,
*The Composite Nambu–Goldstone Higgs*, arXiv:1506.01961 - Roberto Contino,
*The Higgs as a Composite Nambu–Goldstone Boson*, arXiv:1005.4269 - Thomas DeGrand,
*Lattice tests of beyond Standard Model dynamics*, arXiv:1510.05018 - Csaba Csaki, Christophe Grojean and John Terning,
*Alternatives to an Elementary Higgs*, arXiv:1512.00468 - Christopher Hill and Elizabeth Simmons,
*Strong Dynamics and Electroweak Symmetry Breaking*, hep-ph/0203079 (although a bit dated) - Graham Kribs and Ethan Neil,
*Review of strongly-coupled composite dark matter models and lattice simulations*, arXiv:1604.04627 - Sean Tulin and Hai-Bo Yu,
*Dark Matter Self-interactions and Small Scale Structure*, arXiv:1705.02358

In addition to standard textbooks such as those by DeGrand and DeTar, or Gattringer and Lang, the following references on lattice gauge theory are also useful:

- Rajan Gupta,
*Introduction to Lattice QCD*, hep-lat/9807028 - David Kaplan,
*Chiral Symmetry and Lattice Fermions*, arXiv:0912.2560 - Other contributions to the 2009 Les Houches school on
*Modern perspectives in lattice QCD: Quantum field theory and high performance computing*

Last modified 22 January 2018