EF04 Topical Group Community Meeting

US/Eastern
Description
Ayres
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presenting slides https://indico.fnal.gov/event/43221/contributions/185598/attachments/128304/155150/go

big questions
keep in mind: interest is what EW physics to do in next decade; how technically to do so is side question

call for input from community (slides 3/4)
 
summary of ESG

most of results presented in ESG Briefing Book are very limited 
(only S/T parameters for EW precision, only 2 EFT operators at a time for high-energy VV processes, slides 6,9,10,11)

some discussion of systematics, but more on theory systematics than exp. ones (slides 7,8)

global fits: only Higgs results, in k-framework, and EFT (more in suppl. docs.) (slides 12)

One can identify several potentially relevant physics questions that were not addressed in the Briefing Book (slide 13)
 
 
Jessica Metcalfe (slides https://indico.fnal.gov/event/43221/contributions/185600/attachments/128295/155151/Metcalfe_EF04_interest.pdf)
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Vallary Bhopaktar, ANL
 
interests: ssWW, WWW, BSM aQGC, detector performance
past: ssWW, WWW, HL-LHC performance studies, ssWW for Snowmass 2015
 
interest beyond HL-LHC
 
Graham Wilson
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main interest precision W mass at e+e-
focus on ILC, looking at lepton-only methods
 
prior work on polarized W runs
 
semileptonic studies useful for polarization measurements, focus though on mass, room to talk about TGCs
 
Sven Heinemeyer: working on Z mass as well?
GW: that is an interest, but probably unlikely to get to it
Sven: Z mass very important here as parametric input
 
Lailin Xu (slides https://indico.fnal.gov/event/43221/contributions/185600/attachments/128295/155158/SnowmassEF04_BNL_EWK_202005.pdf)
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BNL Omega Group, ATLAS
Viviana Cavaliere, Marc-Andre Pleier, Alessandro Tricoli
postdocs: Gaetano Barone. Jennifer Rolof
 
interest: correlated EW measurements and fits, measurements of ratios to enhance sensitivity to new physics
complementary sensitivity to EFT parameters w/ VBF Higgs
VBS semileptonic final states
 
Jurgen Reuter: issue of semileptonic is that you can't get W masses; plan to look at hadronic channels too?
LX: Don't want to stretch ourselves too thinly, but maybe if we have time/resources left
 
Philippe Chang: WWH to measure Higgs coupling w/o Higgs; also wondering if there is reason for focus on semileptonic instead of looking at same sign
LX: backup slide 5 for question 1; limited group size does not allow to spread too much
 
Junping: many diagrams here, plan to do global fit to extract couplings?
LX: possibility of doing combination
Ayres: at some point, question if we can do fit with all operators, and have correlation matrix for all these multiboson analyses doing fit with many operators would be progress w.r.t. current situation
Alessandro: that is plan of doing ratios: in practice, need to evaluate these correlations among processes; should make it easier to put measurements in global fit
 
Jeffrey Berryhill (slides https://indico.fnal.gov/event/43221/contributions/185600/attachments/128295/155132/snowmass2021_vbs.pdf)
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Jeff, Sergo Jindariani, Aram Apyan; FNAL, CMS
 
longitudinal scattering of boson pairs
find achievable precision of long. polarized cross sections vs collider energy
same-sign, leptonic WZ/ZZ
triple and quartic gauge couplings
limits on dim-6 and dim-8, comparison of sensitivity
 
published results in this area in CMS
 
Ayres: foreseen, when including EFT operators, to perform limits on correlated sets of them?
JB: probably beneficial to agree on how to select them
ongoing discussion on VBS scattering and dim-6 operators in LHC EW WG
MC: MadGraph, WIZARD
Juergen Reuter: there is no MC at the moment which consistently contains both dim-6 and dim-8
MadGraph can take linear and square terms of dim-6, if one wants to have dim-8 must take dim-6 only in square form... not possible have consistent
 
Ayres: has everybody possibility of producing MC they need? Maybe share resources among different groups interested in VV processes?
JB: ATLAS and CMS have experience in different generators, possible to pull resources together
 
Graham: seen discussion mostly from hadron, plans for comparisons with e+e- and linear?
JB: would be interested in seeing comparisons; in e+e- have lower background, but do not have access at high-Q^2
Ayres: in terms of energy reach clearly hadron superior, but maybe some aspects cannot be disentangled at hadron, and can at e+e-
Jurgen: study just started about multiboson production at CLIC, would be happy to bring to Snowmass, and used to compare with HL-LHC and what high-E hadron machine can do (will provide info by email or Slack)
Marc-Andre: it would be interesting to hear case for comparison with lepton machine; issue is that we have all now decade(s) of hadron collider experience; very interested in hearing suggestions and studies at lepton machine
 
Discussion
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suggestions received from survey (https://indico.fnal.gov/event/24264/) 
(slides https://indico.fnal.gov/event/43221/contributions/185598/attachments/128304/155175/May15_projectsuggestions_1.pdf)
 
discussion on big questions (slide 2 on https://indico.fnal.gov/event/43221/contributions/185598/attachments/128304/155150/go)
can we learn more by studying more comprehensively?
there is overlap between our list and the ESG big questions
 
Sven: ESG took available input from experiments as they provided, but not tracked should be realistic in what we can achieve
Ayres: if too much to fully re-evaluate systematics in our group, could do better job, for example, by making statements about having systematics consistently evaluated in various experiments
 
Junping: critical analysis of systematics is in our scope only EW direct measurements are in our group; top and Higgs measurements are discussed in EF03 and EF01
 
Alberto: multi-boson measurements in our purview, and EW production of vector bosons; V+jets in EF05 (but EW parameters in EF04: mW, Z AFB, weak mixing angle...); EF05 gives alpha_s
 
Ayres: alpha_s measurable in many sources; in SM, one of most robust is from Z decay width; in context of SMEFT, Z decay also affected by new physics, and EW precision along cannot disentangle (jet and top observables may have similar issues); hence EF05
 
Jurgen: operators also in backgrounds to, e.g., VBS processes
 
William Shepherd: about operators in background?
Juergen: could imagine pure QCD operators contributing to dijet background of vector boson production analysis, and affect analysis
 
Ayres: not possible to answer questions completely, with fit w/ O(1000) different analyses; but often operators which appear in loop or in background can be constrained by other dedicated measurements. However, we can try to identify operators appearing in loops and backgrounds that are otherwise unconstrained, and how much they mess up
 
Jurgen: should have plots with footnotes indicating which sets of operators are set to 0, probably cannot do with all SMEFT together
 
William: being optimistic here, think could do
 
Junping: definitely thinking about global fit, and expect to resolve degeneracies by adding new e+e- collider to LHC data; this discussion very welcome to happen here
 
Giordon Stark, Alessandro: about EFT in background: big burden on experimental collaborations, would need to provide lots of info about control regions, that requires non-negligible effort
 
Ayres: should devote one of future meetings on SMEFT analyses, what we can and want to do, how much to combine into a global fit



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