------------------------------------------------------------ LHC Higgs Cross Section Working Group LoI ------------------------------------------------------------ After two years of activities the HXSWG is undergoing substantial restructuring while keeping the original motivations. Consequently, our primary goal will remain the same: give EXPs a clear guideline for Higgs analysis, including associated uncertainties. Our plan is to make the HXSWG more effective in supporting the LHC needs, i.e. we propose the new groups 1) light Higgs / property measurements 2) BSM Higgs A lot of discussions are taking place inside ATLAS and CMS on Higgs Combination and Properties. It is the right moment to reinforce the message that the HXSWG is the natural place to keep alive a discussion on theoretical issues, providing tools, theory uncertainties, strategies for property measurement etc. The new structure: The main groups comprise: 0. The production groups: * ggF [H -> gaga, WW, ZZ] Contacts: ATLAS: Biagio di Micco CMS : TH : Daniel de Florian, Kirill Melnikov, Frank Petriello * VBF [H -> gaga, tautau, WW, ZZ] Contacts: ATLAS: Daniela Rebuzzi CMS : TH : Ansgar Denner(tbc), Carlo Oleari * WH/ZH [H -> bb] Contacts: ATLAS: Giacinto Piacquadio CMS : Jim Olsen TH : Stefan Dittmaier, Giancarlo Ferrera * ttH [H -> bb] Contacts: ATLAS: CMS : Jim Olsen TH : Laura Reina, Michael Spira These groups should continue with - the calculation of 8 TeV predictions (and possibly prepare other energies) - provide easy-to-use tools for distributions - include further updates in the predictions - and should cover specific issues related to Higgs decay in each production process (with the most relevant decay channels indicated above [...]) 1. Light Mass (LM) Higgs i) issues concerning XS * BR, in particular issues connected to the decays H -> gamma+gamma, tau+tau, bb, WW and ZZ ii) Higgs property measurements: Higgs mass, (width), sigma*BR, J^PC, couplings (HVV, Yukawa, trilinear, quartic). Discuss main theoretical issues (concerning XS * BR) and create tools to be used by ATLAS and CMS (+CDF+D0) to analyze Higgs boson data available in 2012 and beyond, including branching fractions, couplings to SM particles, anomalies in the present data (gamma+gamma and WW signals), evidence of spin zero and how this possibility could be confirmed in the near future, separation of signal and backgrounds and strategy for measuring the mass and other characteristics of a putative signal. Contacts: ATLAS: Michael Duehrssen, Markus Schumacher CMS : Andre David, Markus Klute TH : Massimiliano Grazzini, Ansgar Denner(tbc), Georg Weiglein 2. MSSM Neutral - Charged Higgs merged Cross sections have to worked out in more detail, more channels, higher precision, similar for distributions. Contacts: ATLAS: Trevor Vickey, Martin Flechl CMS : Monica Vasquez, Sami Lethi TH : Robert Harlander, Michael Kraemer, Pietro Slavich, Michael Spira 3. BSM BMSSM, ..., XMSSM, heavy Higgs bosons Contacts: ATLAS: Krisztian Peters, Sara Diglio CMS : Mario Kadastik, Sara Bolognesi TH : Christophe Groan Branching fractions, couplings, e.g. to an hypothetical invisible sector to determine their current favourite values. Concerning a possible BSM heavy Higgs boson: i) H-> WW,ZZ, Interference, ii) VV-scattering While the signal modeling of a light Higgs is very well studied, additional work is needed in the case when the Higgs is heavy and has a large width. We should plan in particular to discuss the treatment of the Higgs width, and of the signal-background interference effects in parton shower Monte Carlos, fixed order calculations, and their combination. 4. BR (SM, MSSM) SM BRs to be refined if required (by new calculations...) MSSM BRs to be worked out for general applications Distributions? Contacts: ATLAS: Daniela Rebuzzi CMS : Ivica Puljak TH : Alexander Mueck, Sven Heinemeyer 5. PDF subgroup will act as contact for PDF4LHC and as a support group. Contacts: TH : Joey Huston, Stefano Forte, Robert Thorne 6. NLO MC experts will be kept to give the needed support when required by each subgroup. Contacts: TH : Stefano Frixione(tbc), Frank Krauss(tbc), Fabio Maltoni(tbc), Paolo Nason(tbc) The previous PO group is integrated (by definition!) in LM and the HM part of BSM. While keeping the existing Higgs production and decay subgroups, we think that LM comprises the most important new issues for next two years (even though we should pursue also a heavy Higgs (within BSM), especially in case of total exclusion of light Higgs with 2012 data.) Where necessary, links with corresponding ATLAS/CMS working groups should be established. Similarly, any theoretical issues should be collected by the contacts. Feedbacks to the collaborations of any agreed recommendations should be made immediately. April 10, 2012 Sven Heinemeyer, Chiara Mariotti, Giampiero Passarino, Reisaburo Tanaka