New Heavy Gauge Bosons at CMS ClaudiaElisabeth Wulz

New Heavy Gauge Bosons at CMS Claudia-Elisabeth Wulz On behalf of the CMS Collaboration Institute of High Energy Physics Vienna Austrian Academy of Sciences 7 July 2012

New heavy gauge bosons To solve known shortcomings of the Standard Model, extensions have been proposed. The SM gauge group SU(3)Cx. SU(2)Lx. U(1)Y can be extended by: - An extra U(1) group, giving rise to a neutral heavy vector boson Z’ - An extra SU(2) group, giving rise to a charged heavy vector boson W’ Model examples: - Sequential Standard Model (SSM): new bosons have similar couplings as W, Z in SM - Left-right symmetric models: SU(2)Lx. SU(2)R - Superstring-inspired E 6 models: E 6 SO(10)x. U(1)y SU(5)x. U(1)cx. U(1)y. Only one linear combination G leads to particles at the Te. V scale: G = cosq U(1)c- sinq U(1)y. q = 0: y-model - More complicated scenarios predict a tower of new gauge bosons (Wn, Zn, or gravitons Gn), such as technicolor or extra dimension models. C. -E. Wulz 2 ICHEP, July 2012

Z’ l+l- (l = e, m) Many Z’ models predict narrow resonances decaying to dileptons. Event selection: ET (e 1, e 2) > 35 Ge. V, p. T (m 1, m 2) > 45 Ge. V, plus isolation criteria Backgrounds: _ - Z/g*, tt, t. W, VV, Z tt, multijets with ≥ 1 jet reconstructed as lepton - estimated by fitting data with appropriate function M(Z’SSM) > 2590 Ge. V M(Z’y) > 2260 Ge. V Rs = sll(Z’)/sll(Z) CMS PAS EXO-12 -015, hep-ex 1206. 1849, CMS PAS EXO-11 -019 C. -E. Wulz 3 ICHEP, July 2012

Z’ tt There are non-universal scenarios in which the Z’ couples preferentially to thirdgeneration fermions. Final states studied: tetm, teth, tmth, thth. n’s in final state do not allow to reconstruct mass of tt system. Event selection: 2 t candidates with p. T between 15 and 35 Ge. V, h < 2. 1, isolation criteria, no b-jets Backgrounds: _ DY Z tt, W+jets, tt, VV, QCD Backgrounds are estimated from data where possible. Effective visible mass te tm thth M(Z’SSM) > 1. 4 Te. V M(Z’y) > 1. 1 Te. V hep-ex 1206. 1725 submitted to PLB CMS PAS EXO-11 -031 C. -E. Wulz 4 ICHEP, July 2012

W’ ln without W-W’ interference Models studied: - W’SSM with SM-like couplings, with W’SSM tb allowed - Kaluza-Klein W 2 KK in split UED framework miss, energy-balanced Event selection: ~back-to-back _ isol. l+ET Backgrounds: W ln, QCD, tt+single top, DY, VV from data W’ en W’ mn CMS PAS EXO-12 -010 C. -E. Wulz M(W’SSM) > 2. 8 Te. V M(W 2 KK) > 1. 25 Te. V (m = 0. 05 Te. V) M(W 2 KK) > 3. 3 Te. V (m = 10 Te. V) 5 ICHEP, July 2012

W’ ln with W-W’ interference A left-handed WL’ can interfere with the W. Studies were performed with 7 Te. V data. Limits for a WR’ have also been derived. hep-ex 1204. 4764 submitted to JHEP C. -E. Wulz M(WR’SSM) > 2. 5 Te. V M(WL’SSM) > 2. 63 Te. V (constructive interference) M(WL’SSM) > 2. 43 Te. V (destructive interference) 6 ICHEP, July 2012

W’ tb • WR’ decays to leptons suppressed if M(n. R) > M(W’) search in hadronic final states important. Decay chain: W’ tb Wbb lnbb. jet 1(jet 2) > 100(40) Ge. V, ≥ 1 b-tag Event selection: isol. e( m ) with p > 35(32) Ge. V, E T T _ Backgrounds: tt+single top, W( ln)+jets, Z/g* ( ll)+jets, QCD, VV New BDT analysis for signal/background discrimination with ~50 variables (object and event kinematics, top reconstruction, angular correlations). Comparison of BDT and invariant mass analyses CMS PAS EXO-12 -001 C. -E. Wulz 7 ICHEP, July 2012

W’ tb Most general model-independent LO Lagrangian for a W’ coupling to SM fermions: Mass limit and constraints of W’ gauge coupling for a set of left- and right-handed coupling combinations have been set: M(WR’) > 1. 85 Te. V Contours of W’ mass at which the observed 95% CL cross-section upper limit equals the predicted cross-section C. -E. Wulz 8 ICHEP, July 2012

W’ td _ • Tevatron measurement of forward-backward asymmetry at high tt inv. mass • Possible explanation: light W’ • N(W’-) > N(W’+) at LHC -> aids in reconstructing the W’ Decay chain: pp t. W’ ttd, with semileptonic t-decays plus a jet in final state. Difference of yields for t-+d and t++d invariant mass distributions (charge assignment from leptonic top decay): hep-ex 1206. 3921, CMS PAS EXO-11 -056 C. -E. Wulz 9 ICHEP, July 2012

W’ td M(W’) > 839 Ge. V C. -E. Wulz 10 ICHEP, July 2012

W’, GRS VZ wide jet + lepton pair l W’SSM ZW lljj, GRS ZZ lljj l W’, G Z • 2 -fermion systems boosted for heavy resonance Event selection: W, Z merged based on high-p. T Z candidates from lepton pair and jet wide jet well separated from leptons 95% CL exclusion limits Backgrounds: from data _ W+jets, tt, g. V+jets, Z/g*+jets, ZZ, VV+jets CMS PAS EXO-11 -081 C. -E. Wulz 11 ICHEP, July 2012

Conclusions • CMS has studied scenarios for new heavy gauge bosons. • Although no signals for new physics have been found yet, limits on masses and other quantities have been set. • Details may be found here: https: //twiki. cern. ch/twiki/bin/view/CMSPublic/Physics. Results. EXO We are looking forward to more LHC data! C. -E. Wulz 12 ICHEP, July 2012