TreeLevelPlatformVersion
References and links
What one looks up without wanting to read a whole page again: the shortcuts, the formats, the addresses.
Shortcuts
| Gesture | Effect |
|---|---|
| ⌘N · ⌘O · ⌘SCtrl N · Ctrl O · Ctrl SCreate Document | New document, open, save — like any document of the system. |
| ⌘+ · ⌘− · ⌘0Ctrl + · Ctrl − · Ctrl 0 | Zoom in, zoom out, recentre the canvas on the diagram. |
| ⌫Delthe trash in the toolbar | Erase what is selected — a vertex, the end of a leg. |
| ⌥⌘← · ⌥⌘→ | Page through the sample, event by event. |
Pinching on the trackpad zooms as well, and dragging the background with the Select tool moves the drawing.
The files
.feyndiag | A TreeLevel document: the theory and the diagrams. It reads back as it is on another machine, since it carries its copy of the model. |
|---|---|
.feyn | A model written by hand — fields, parameters, interaction Lagrangian. The language is described in Theories. |
| UFO folder | The format FeynRules produces for MadGraph: particles.py, parameters.py, couplings.py, vertices.py. TreeLevel imports it as a model. |
.lhe | Les Houches: the events at parton level, as TreeLevel draws them and as an external generator picks them up. |
.hepmc | HepMC3: the complete event, shower and hadronisation included, with the parentage of the particles. |
Where these files live on disk is told on the Installation page.
The generators
| Pythia 8 | Picks up the computed event: parton shower, hadronisation, decays. It is also the one that drives the collider mode.It is also the one that drives the Machine source. |
|---|---|
| Herwig 7 | The same thing, with an angular-ordered shower and a cluster model for hadronisation: two answers are better than one. |
| Sherpa 3 | Computes the process itself from the beams and the final state, then dresses it. |
| WHIZARD 3 | Rewrites each process in Fortran and compiles it at run time — hence its precision on lepton machines, and hence its weight. |
| CalcHEP 3 | Matrix element and cross section, without a shower: a second opinion on the number TreeLevel computes. |
On the iPad, Pythia 8 only, as a module downloaded from the settings: see Installation.
They install separately, and for good reasons: see Installation.
The other pages
- Tutorials — six guided walks, from the Z peak to baryon number violation.
- Physics — the conventions, what the engine computes exactly, and what it was validated against.
- Theories — writing a model, or importing one.
- Installation — the application, the generators, where the files are.
- Support — frequent questions, and how to report a problem.
Where the methods come from
TreeLevel invents none of these algorithms; it applies them. Naming them lets one know what one is reading in a result.
- RAMBO, flat phase space at constant weight — Kleiss, Stirling and Ellis (1986). It is what draws the momenta beyond 2 → 2.
- anti-kT, the jet algorithm — Cacciari, Salam and Soyez (2008).
- The Les Houches accord for parton-level events, and HepMC3 for the complete event: the two formats through which generators speak to one another.
- FeynRules and the UFO format — the vertex conventions TreeLevel conforms to, checked one by one against MadGraph's Standard Model.
- Review of Particle Physics — masses, widths and branching ratios of the
Hadronsmodel are confronted with it, to the precision the PDG displays. - KaTeX (MIT) renders the formulas of the application and of this site.