# Mass methods

### From Wiki Les Houches 09

(Difference between revisions)

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| <math>M_{eff}</math> | | <math>M_{eff}</math> | ||

| hep-ph/9610544[http://arxiv.org/abs/hep-ph/9610544], hep-ph/0006276[http://arxiv.org/abs/hep-ph/0006276] | | hep-ph/9610544[http://arxiv.org/abs/hep-ph/9610544], hep-ph/0006276[http://arxiv.org/abs/hep-ph/0006276] | ||

- | | Discovery of New Physics with massive particles | + | | Discovery of New Physics with massive particles. |

- | | Bad, quoted to be 20%-50%, but needs to be interpreted in a specific model. | + | | Bad, quoted to be 20%-50% in references, but needs to be interpreted in a specific model. |

- | | | + | | Discovery above SM contribution and estimating mass scale of particles with dominant cross section. |

| Does not identify process, but gives some information on particle content of dominant topologies. | | Does not identify process, but gives some information on particle content of dominant topologies. | ||

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|- | |- | ||

| <math>Edges</math> | | <math>Edges</math> | ||

- | | (lots) | + | | hep-ph/9610544[http://arxiv.org/abs/hep-ph/9610544] (lots) |

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## Revision as of 16:07, 24 June 2009

Variable/Method | Reference(s)/Code | Realm of Applicability | Precision | Good for | Fails for | Unknown/Future directions |
---|---|---|---|---|---|---|

M_{T}
| (ancient) | one missing particle | ||||

M_{eff}
| hep-ph/9610544[1], hep-ph/0006276[2] | Discovery of New Physics with massive particles. | Bad, quoted to be 20%-50% in references, but needs to be interpreted in a specific model. | Discovery above SM contribution and estimating mass scale of particles with dominant cross section. | Does not identify process, but gives some information on particle content of dominant topologies. | |

H_{T}
| always | does not identify process in any way | ||||

Edges
| hep-ph/9610544[3] (lots) | Mass differences in leptonic decays. | Dependence on mass scale is weak. | Intermediate 3-body decays? Combinatoric (other side) jets not considered. Calorimeter nonlinearity? | ||

M_{T2}
| hep-ph/9906349[4] | |||||

M_{T2} kink ("stransverse" mass)
| arXiv:0709.0288[5] | 4-body final state, 2 missing | large mass differences and large p_{T}
| small mass differences or no p_{T}
| ||

M_{Tn}
| 4-body final state, n missing
| |||||

M_{Tgen}
| arXiv:0708.1028[6] | |||||

M_{2C}
| arXiv:0712.0943[7] | |||||

M_{3C}
| arXiv:0811.2138[8] | |||||

arXiv:0812.1042[9] | ||||||

Exactly-constrained Polynomials | arXiv:0707.0030[10] | 4 on-shell intermediate resonances, 2 missing | Apply to squark-neutralino2-slepton-neutralino1 cascade where other side is squark-neutralino1. | |||

Multi-event Polynomial intersection | arXiv:0802.4290[11] | 5 or more on-shell intermediate resonances, 2 missing | Statistics of histograms created with n-event subsets; If mass differences are fixed and the masses are increased, what happens? (Sabine Kraml); Develop methods for asymmetric chains and < 6 intermediate resonances. |

- How can we define "Precision" in a manner that lets us meaningfully compare different methods? A lot of process-specific assumptions and backgrounds usually enter the application of each method.
- In general, all methods need to be systematically tested in cases where the assumptions needed for the method are
*not*satisfied. - Appropriate consideration of ISR/FSR jets is not usually considered. Requires 2->3 matrix elements where the hard scattering process includes a possible extra hard quark/gluon radiation.