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====== Dark matter searches at the LHC ======

===== Projects: =====


==== Recommendations for presenting LHC effective DM results ====

Goal - create a short document recommending:

1) How to present effective direct detection cross section limits from monojet (or mono-anything) searches while making clear the limits of the effective theory and the role of a light mediator mass.

2) What is the most useful set of operators to present results for, and how can the results be presented to be most useful for recasting to a full model.

Interested people:  
^Name ^ e-mail ^
| Kiel Howe | howek@stanford.edu |
| Brian Shuve | bshuve@perimeterinstitute.ca |
| Gordan Krnjaic | gkrnjaic@perimeterinstitute.ca |
| Andreas Goudelis | andreas.goudelis@lapth.cnrs.fr |
| Csaba Balazs | csaba.balazs@monash.edu |
| Yun Jiang | yunjiang@ucdavis.edu |
| Alex Arbey | alexandre.arbey@ens-lyon.fr |
| Fawzi Boudjema| boudjema@lapth.cnrs.fr|

==== Improving sensitivity of monojet-like searches ====

Goal - determine the best set of cuts to study ISR + MET final states for single insertions of effective Dark Matter operators (for example, the Harnik et. al. razor recast)

Interested people:  
^Name ^ e-mail ^
| Marija Marjanovic   | marija.marjanovic@cern.ch  |

==== Exploring other signal channels for simplest UV completions of effective operators ====

Goal - in the region where monojet constraints allow fairly large couplings of mediators, are there other unexplored channels to look in? Possible examples:
  * Dijet resonance
  * Dijet resonance + missing energy
  * t-channnel mediator pair production through light DM exchange
  * Di-top resonance or di-vector-like-quark resonance for gluon operator

Should we tie this in with paired resonances working group?

Interested people:  
^Name ^ e-mail ^
| Kiel Howe  | howek@stanford.edu   |
| Brian Shuve | bshuve@perimeterinstitute.ca |
| Andreas Goudelis | andreas.goudelis@lapth.cnrs.fr |
| Aoife Bharucha | aoife.bharucha@desy.de |
| Gordan Krnjaic | gkrnjaic@perimeterinstitute.ca|

==== Interpretation of the LHC monojet searches in terms of indirect detection and relic density ====

Goal - the monojet searches at the LHC are currently reinterpreted (in a simple effective model with one mediator and one DM particle) in terms of dark matter scattering cross-sections with matter, as in direct detection experiments. Can we set also limits on indirect detection (gamma, proton, anti-proton spectra)? And can we deduce a lower limit on the relic density? Additional questions:
  * which effective models are the most strongly constrained?
  * what if more than one mediator/operator is present?
  * which models are interesting?
  * can we reinterpret the DM direct search results in terms of LHC cross-section?

Interested people:  
^Name ^ e-mail ^
| Alex Arbey | alexandre.arbey@ens-lyon.fr |
| Genevieve Belanger | belanger@lapth.cnrs.fr |
| Andreas Goudelis | andreas.goudelis@lapth.cnrs.fr |
| Nazila Mahmoudi | nazila@cern.ch |
| Sacha Pukhov | pukhov@lapth.cnrs.fr |
| Yun Jiang | yunjiang@ucdavis.edu |
| Csaba Balazs | csaba.balazs@monash.edu |
| Fawzi Boudjema| boudjema@lapth.cnrs.fr|

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====== More General Thoughts ======

**Questions:**
  * Reference masses for DM on mediator plots (Why 50 and 500? Why not 5 GeV)
  * Experimental limits on more effective operators (including interesting flavor structures?)
  * Is there a convention for plots that makes clear the limited validity of the effective theory?
  * Does anything change for t-channel mediators?
  * What extensions beyond monojet/monophoton searches can set stronger limits on effective operators? E.g. production in association with 3rd generation (e.g. http://xxx.lanl.gov/abs/1303.6638v1), Z/leptons + MET (e.g. http://arxiv.org/abs/1212.3352), ...
  * What can shape/variable analyses add to the sensitivity of these searches? (e.g. the Razor analysis in http://arxiv.org/abs/arXiv:1203.1662) 

**References:**

LHC limits:
  * ATLAS 8 TeV monojet http://cdsweb.cern.ch/record/1493486
  * CMS 8 TeV monojet http://cds.cern.ch/record/1525585?ln=en (figs. 8 and 9 were shown in organizing meeting)
  * ...

Effective DM theory:
  * Fox et. al. http://arxiv.org/abs/1109.4398v1 (the key to understanding the plots in the CMS paper!)
  * Tait et. al. http://arxiv.org/abs/1108.1196
  * ...

Mediator production:
  * Dijet resonances: An et al. http://arxiv.org/abs/1202.2894v1
  * Associated production: An et al. http://arxiv.org/abs/1212.2221
  * and references therein
===== Beyond Effective dark matter =====

  * How can limits easily be translated to models with multiple mediators / multiple effective operators?
  * How can the relevance (or irrelevance) of effective operator limits to full models like SUSY best be expressed?
  * What DM-motivated searches can not be expressed in an effective operators / single mediator picture? 


===== Breit-Wigner cross-section =====
$\sigma_{LHC}(pp \to \chi \bar{\chi} +X)\sim \left|\frac{g_q g_\chi E}{(s-M_X^2)+iM_X\Gamma_X/2}\right|^2 \sim \frac{1}{\Lambda^4}$\\
where $E$ is of order the partonic center-of-mass energy.\\
Two regions to study/search
  * $M_X >> M_\chi, E_{cut}$
  * $M_X \ge M_\chi, E_{cut}$
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