LHC Higgs Combination Group (LHC-HCG)

Charge

The working group has been charged to produce a combined Higgs result from LHC (ATLAS and CMS) Higgs analyses. The mandate of the group is as follows

• The implementation of Higgs boson theory aspects based on LHC Higgs XS WG recommendations will be discussed within the group. If needed, the group will request additional information from the LHC Higgs XS WG.
• Monte Carlo generators and systematic variations are to be compared and unified where profitable and consistent with the overall MC and systematic uncertainty strategy in the individual experiments. This could result in sharing MC samples between ATLAS and CMS.
• Technical aspects regarding the construction and usage of likelihood functions are to be discussed and solutions implemented as homogeneously as possible, including common naming conventions and tools. This includes efforts to construct simplified likelihood functions.

Composition

Other members are: ATLAS and CMS spokespeople and physics coordinators and participating experts as and when needed.

Run 2 combinations

• Zy ATLAS CMS combination
• Fiducial and differential informations for possible future combination

Communication tools

e-group mailing list	For group's global issues, announcement of group meetings, meeting summary, ... Follow this link to subscribe yourself to the mailing list.
Contacts e-group mailing list	For contact persons (restricted access).
Indico pages	Group's workshop and subgroup meeting agenda system.
TWiki page	Static information site that is updated mainly by contact persons. Group organization, minutes, documents, link for tools and meetings, ...

Software

The agreed framework for the Higgs combination is the RooStats package available from ROOT releases and RooFit's RooWorkspace is the preferred format for sharing the data and likelihood model.

Discussion TWiki

• Parameters of interest
• Nuisance Parameters

GitLab repository

Main Repository in GitLab

The levels of repositories follows the structure shown in the image below. To clone a sub-repository use

git clone https://gitlab.cern.ch/lhc-hcg/Run-X/sub-project/repo.git

Show figure Hide

Run 1 composition

Run1 contacts Hide

Run1 Documentation

Run1 combination documents Hide

Support Note SVN
Editors:
ATLAS:	contacts + Tim Adye, Stefan Gadatsch, Fangzhou Zhang, Hongtao Yang & Eilam Gross
CMS:	All Contacts + Marco Pieri, Mingshui Chen, Nick Wardle
ATLAS Combination	Conf
CMS Combination	Twiki

Paper SVN
Contact Editors:
ATLAS:	Daniel Froidevaux (main), Tim Adye, Stefan Gadatsch, Fangzhou Zhang & Eilam Gross
CMS:	Marco Pieri, Mingshui Chen, Nick Wardle
ATLAS Combination	Conf
CMS Combination	Twiki, arXiv

SVN Repository (Outdated)

SVN Repository

Couplings Work Spaces

Support note SVN

Paper: SVN

Some simple SVN instructions are at: https://svn.cern.ch/reps/lhchcg/doc/using-svn.txt

The repository can be accessed like so:

--------------------------------------------------
svn co svn+ssh://svn.cern.ch/reps/lhchcg
svn co https://svn.cern.ch/reps/lhchcg
--------------------------------------------------

We should start organizing some materials there, even if for now they are based on toy data:
- the WorkSpaces for ATLAS and CMS
- the combined WorkSpace
- any pieces of codes that could/should be shared
- documentation
- etc

Links

Past meetings: https://indico.cern.ch/categoryDisplay.py?categId=3328

Useful Material

• Phystat 2011 talk: RooStats for searches (G. Schott)
• Phystat 2011 talk: Combining ATLAS and CMS Higgs searches (K. Cranmer)