Minutes of the HXSWG3 Meeting of December 8th 2014
http://indico.cern.ch/event/354568/
- Introduction
http://indico.cern.ch/event/354568/contribution/0/material/slides/0.pdf
- Benchmarks for NMSSM Higgs pair production (by Maggie)
http://indico.cern.ch/event/354568/contribution/1/material/slides/0.pdf
Summary:
NMSSMCalc has been used for calculations http://www.itp.kit.edu/~maggie/NMSSMCALC/
Examined the possibility that there are 2 NMSSM Higgs bosons that make up the 125-GeV signal and it is found still viable; Decays of the type H -> hHs -> XXYY (i.e. φ -> φ1φ2 style) and H->ZAs (i.e. to vector bosons) have been examined. All in the context of natural NMSSM.
Q: Do the plots in slides 11-12 represent different predictions for different tanbeta values?
A: Not only, all the other parameters of the theory are also varied
Q: Is the large BR of the singlet -> gamma gamma due to squark loops? Seems unlikely, because they must be very heavy. Charged Higgsinos could contribute more
A: This needs to be check.
Q: Is the A_s coupling to bb forbidden, or simply the coupling to charginos and squarks are dominant?
A: It is suppressed because the more the Higgs boson is singlet-like, the less it couples to SM particles
Q: When you show the points of predictions, it’s problematic for experimentalists. What are the best parameters to scan?
A: We have in fact plots for the parameter space, but they are more helpful to understand what is happening on the theoretical side than to be used for experimental limits.
Q: How do we convert a limit on cross section to a limit on the parameters of the theory?
A: It can be done with a multidimensional fit, once you know the cross section limit, but it is not trivial: NMSSM is different wrt MSSM because at tree level in the latter you just have two parameters, the former is much more varied and a limit in the parameter space from the cross section can be non-trivial
- Benchmark points for the NMSSM (by Wim de Boer)
http://indico.cern.ch/event/354568/contribution/2/material/slides/0.pdf
Summary:
Code used for the results: NMSSMTools
examination of both natural and unnatural NMSSM. Natural NMSSM example: H3 -> H2 + H1 -> WWbb/bbbb etc, where H2 is the 125-GeV Higgs; unnatural NMSSM with A and H3 at ~ 1 TeV and H1, H2 close to 125 GeV is examined and Higgs BRs are given
Q: Which is the SM-like Higgs boson in slide 8?
A: H_2 is always assumed to be the 125 Higgs boson
Q: Regarding NMSSMTools: when I try to compute BRs in the SM limit, I get different BRs to what I should get, ~15-20% too low. Can the authors comments?
A: Have you tried the option to go through one or two offshell vector bosons? You need to check that. You can compare your predictions with NMSSMCALC which includes the off-shell effects and state-of-the-art higher order corrections. If the off-shell decays play a role depends of course on the mass of the Higgs boson you are considering.
Comment: It would be good to have a comprehensive review of all the tools available for predictions in NMSSM
A: We should put this item in the next NMSSM meeting
Q: I wonder if the WWbb final state is really the best one for HH decays? Isn’t tautau better? Smaller BR but higher purity
A: First simulations show similar sensitivities
- NMSSM with a singlino LSP: possible challenges for searches for supersymmetry at the LHC (Ulrich Ellwanger)
http://indico.cern.ch/event/354568/contribution/3/material/slides/0.pdf
Summary:
The talk focuses on a specific case in which heavy sparticles do not decay to the LSP directly, but through a cascade via NLSP; in that case if the signatures may have much less MET. Examples of signatures that have a higgs pair plus jets, e.g. q~ q~ -> q NLSP q NLSP -> a1 h1 a1 h1 with h1 to bb
Q: Coming back to the question: what would you like to get as information from experimental results? What would be useful as input?
A: Mostly, the point is the detection of final states where not only you have two higgses, but in an environment where you have other “exotic” objects
- Ideal Higgs scenario after the h125 measurements (by Chris Potter) : postponed
http://indico.cern.ch/event/354568/contribution/4/material/slides/0.pdf
Because of Vidyo problems, the talk was postponed to next meeting
- Detectability of light pseudoscalars in the NMSSM (Nils-Erik Bomark)
http://indico.cern.ch/event/354568/contribution/5/material/slides/3.pdf
Summary:
Focus on searches for a1; a1 comes from decays of heavier Higgses; mostly H->aa, H->ah type of signatures
Q: What is the difference between the CMS and ATLAS points in slide 16?
A: The extrapolation is done using the current results from the two experiments
Q: Why did you choose such a big mass window (122-129)?
A: It’s to allow proper accounting for theoretical errors
Comment: The problem is that for experiments triggering on bb or tautau below 60 GeV invariant mass is problematic in Run2
A: We will probably be sensitive for high tanbeta only, but it’s something to consider.
- General discussion:
Sven: most of the studies presented show studies in the low tanbeta region. It would be interesting to look how predictions in MSSM translate in NMSSM, and then the high tanbeta region would be critical.
Maggie: in NMSSM, low values of tanbeta are preferred. But it would be interesting to better study the differences between MSSM and NMSSM and how to distinguish among the two.
John: there’s a large range of possible cross sections for a multitude of signatures: experimentalist should give an idea on the range of sensitivity.
Overall conclusions:
We need a review talk that is dedicated to tools used to perform NMSSM calculations
The talk by Chris Potter will be postponed till the next meeting. Talk by Carlos Wagner will go to the next meeting as well.
We will make a collection of all the signatures that were discussed today and we will give them to the experimentals to give some input; the idea is to see if for some of them that interest is expressed some easy benchmark is possible to be defined or at least some restricted set of numbers
After these items are done we can have the next meeting