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This summary presents key highlights from the Electroweak (EWK) and Beyond-the-Standard-Model (BSM) sessions at the XVIth Workshop on Deep Inelastic Scattering in London, April 2008. With 42 talks spanning various topics, special focus was placed on trilinear gauge couplings, neutral and charged currents, and Yukawa couplings. Major experimental achievements from CDF, DØ, CMS, and ATLAS were discussed, showcasing new results and phenomenological insights that test the electroweak theory at unprecedented precision, as we edge closer to discovering the elusive Higgs boson.
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Electroweak Summary Chris Hays, Oxford University for the EWK/BSM session conveners: Michael Kramer Dave South Filip Zarnecki XVIth Workshop on Deep Inelastic Scattering London, England April 10, 2008
Electroweak and Beyond-the-Standard-Model Session • 42 talks • 17 in this summary, 25 in BSM summary • 10 additional talks in joint sessions with HFS, SF • 4 in this summary, 6 in HFS/SF summaries • Many new results shown • Impossible to show all, or to give those shown justice • 420 minutes in 20 slides • Apologies to those missed Electroweak Summary, DIS 2008
The Experiments in a Nutshell • CMS & ATLAS • Looking forward to data! • ZEUS & H1 & NuTeV • Look at all our data! • CDF & DØ & NA48/62 • Looking forward to more data! Electroweak Summary, DIS 2008
The Electroweak Theory • Before symmetry breaking: SU(2)Lx U(1)Y gauge symmetry Higgs term gauge term fermion term Yukawa term • After symmetry breaking: U(1)EM gauge symmetry kinetic Higgs-gauge interaction Quartic gauge interaction Yukawa charged current neutral current Higgs Trilinear gauge interaction Electroweak Summary, DIS 2008
Trilinear Gauge Couplings • Probe WW vertex with W production at the Tevatron Y. Maravin’s talk • t- and u-channels dominate cross section • How do you see the s-channel? Interference effects Compare data to non-SM trilinear-gauge-coupling predictions 2.6 “dip” significance arXiv:0803.0030 Electroweak Summary, DIS 2008
Trilinear Gauge Couplings • Tevatron only place to separately probe WWZ and WW vertices D. Waters’ talk • CDF has observed WZ production at the 6 level PRL 98, 161801 PRD 76, 111104(R) Electroweak Summary, DIS 2008
Trilinear Gauge Couplings • No neutral trilinear couplings in the SM • Tevatron experiments test this prediction with measurements of Z and ZZ production Y. Maravin’s talk arXiv:0712.0599 CDF: first measurement of ZZ production 4.4 significance D. Waters’ talk arXiv:0801.4806 Electroweak Summary, DIS 2008
Neutral Current • HERA can probe electron and quark neutral current couplings ZEUS: New measurements of quark couplings with global fit K. Nagano’s talk Electroweak Summary, DIS 2008
Neutral and Charged Currents • NuTeV extracts sin2W using ratio of NC to CC: Update with fit of s/s asymmetry, K+e3 BR, d/u PDF uncertainties Additional effects still to be included: EWK PDF corrections, mc, ... K. McFarland's talk Electroweak Summary, DIS 2008
Charged Current • NA48/62 at CERN tests universality of e and CC couplings 2.477 x 10-5 in SM trigger dominated background dominated Analysis progressing with 2007 data: use data to constrain → e backgrounds E. Goudzovski's talk Preparing for 2011 run to measure BR(K± → ±): Electroweak Summary, DIS 2008
Charged Current • HERA probes V-A structure of the charged current with polarized electron beam K. Nagano’s talk Electroweak Summary, DIS 2008
Charged Current • Tevatron probes Wtb vertex by measuring W helicity C. Potter’s talk Electroweak Summary, DIS 2008
Charged Current CDF: t+s = 2.2 ± 0.7 pb (3.7 significance), |Vtb| > 0.66 • Tevatron directly constrains Vtb with single top production DØ: t+s = 4.7 ± 1.3 pb (3.6 significance), |Vtb| > 0.68 D. Hirschbühl’s talk LHC: |Vtb| to 5% with 10 fb-1 R. Hawkings' talk Electroweak Summary, DIS 2008
Yukawa Couplings • Top Yukawa coupling suspiciously close to 1 • CDF & DØ have updated their measurements with 2 fb-1 P. Mehtälä's talk LHC: mt to 1 GeV with 1 fb-1 N. Besson's talk Electroweak Summary, DIS 2008
Yukawa Couplings • Independently determine top mass from production cross section mt = 170 ± 7 GeV D. Cho's talk Electroweak Summary, DIS 2008
Kinetic Terms • Indirectly constrain Higgs mass using Electroweak parameters • Higgs loop corrections to the W mass Assuming mt ~ 1 GeV and mW ~ 10 MeV (LHC projections) New top mass improves consistency with SM mH = 87+36-27 GeV, mH < 160 (190) GeV N. Besson's talk Electroweak Summary, DIS 2008
Kinetic Terms B. Tuchming's talk • Higgs searches heating up at the Tevatron • Low-mass searches focus on WH, ZH, with H → bb; New: VBF H → • High-mass searches focus on H → WW ZH WH VBF H D. Hidas' talk Electroweak Summary, DIS 2008
Kinetic Terms • LHC experiments have determined combined Higgs sensitivity Discovery Exclusion D. Fortin's talk Electroweak Summary, DIS 2008
The Experiments Revisited • CMS & ATLAS • Wish we had collision data… • ZEUS & H1 & NuTeV • Too bad we won’t get any more data… • CDF & DØ & NA 48/62 • Will we get enough data? Electroweak Summary, DIS 2008
Summary • New results test Electroweak theory at unprecedented level • Input parameters growing ever more precise • Rapidly approaching the last piece of the Electroweak puzzle: The Higgs Boson “Well, either we’ve found the Higgs boson, or Fred’s just put the kettle on.” Electroweak Summary, DIS 2008
Backup Electroweak Summary, DIS 2008
Tevatron Higgs Sensitivity • Recent improvements and projections Electroweak Summary, DIS 2008
