Legend:
Q: question
A: answer
C: comment
AI: action item
Minutes:
intro (Christian)
DMsimp (Luca)
Q/p3: sensible to have LH and RH couplings at the same time?
Q/p4: F3S?
Q/p5: “NLO should be added by hand” for DD: what does it mean? Why difficult for DD but not ID?
A: for RD, MadDM can’t do NLO automatically
Q: currently working on implementing NLO, what are the hurdles?
A: some subtleties, at colliders pp → DMDM+j because of t-channel resonant processes, needs care when using the resonance subtraction scheme, Benjamin is testing it
Q: how could we map e.g. Tim’s paper or other papers to this model? (e.g. by comparing Lagrangians)
A: easy to map through Lagrangians, though specific coupling choices may be different.
Q: did not see a link in the talk, could you share it already now? Then others can start playing around with it.
A: plan is to make it public very soon, would like to check NLO part
Q: is the LO implementation OK (from a physics perspective)?
A: yes
AI: make UFO public so that other teams can map their results to that. It can be also a preliminary version that can do LO only, still valid for general conclusion. LHC DM can assist (e.g. using its git area)
Report on the implementation by Haipeng et al. (Haipeng)
Q: are you comfortable sharing it on git?
A: yes, in a few days
C: please circulate the link once available
Q: is it a LO UFO?
A: yes
Q: is the model identical to the S3M_uni and S3D_uni implementation of DMsimp?
A: I think so, for RH u quarks
Q: how do you plan to prove that the two map to each other?
A: first check total xsecs (most straight forward), then differential distributions at parton level
General discussion:
Q: Are there any more UFOs available besides the two presented today and the other two used by ATLAS and CMS?
A: Kirtiman & Tim happy to help validating the Ăśber-UFO against their own implementation (but would rather not share it)
A: Laura, Jerome, Michel have Feynrules for their implementation, but UFO file exists and has to be found; there will be some overlap in functionality and can help with testing that
AI: find + make UFO shared? LHC DM can assist (e.g. using its git area)
A: no conclusive answer possible for people/groups not represented here in person
Q: does scalar DM give different physics?
C: in RD, a clear difference due to different number of annihilation diagrams
C: this comes from additional diagrams (3-body interaction, d-wave vs p-wave)
C: at colliders, scalar DM can give a sizeable difference in rates, possibly also distributions
C: I think this can be quite different at colliders, for scalar DM mediator and fermion DM through different production mechanisms
Q: order of magnitude of cross sections for collider signatures similar, don’t expect qualitative difference between different types of DM (Dirac, Majorana, scalar, vector)
C: larger importance of t-channel diagrams for scalars
C: difference through mediator width + because of different helicity suppressions → would be good to compare basic kinematics at truth level
Conclusions:
AI: will share UFOs that are available (wherever authors comfortable with sharing)
AI: will share the DMSimp_t UFO:
~now: preliminary version for LO now so that people can start looking into it
once NLO validated: final version
AI: compare different UFOs for representative scenarios:
cross-sections
differential distributions
AI: systematically study qualitative differences from different choices for nature of DM (Dirac, Majorana, scalar, vector)
AI: next meeting end of July