Heavy charged gauge boson W search at Hadron

Heavy charged gauge boson, W’, search at Hadron Colliders Yu. Chul Yang (Kyungpook National University) (PPP 9, NCU, Taiwan, June 04, 2011) ü This talk is based on the result of Search for W’ decaying to electron and MET in 5. 3 fb-1 @CDF and 36 pb-1@CMS. June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Motivation (W’ gauge boson) l Left-Right Symmetric Model ü Of weak interaction by spontaneous symmetry breaking in the right-handed sector, W’ boson obtains its mass SU(2)R X SU(2)L X U(1)B-L l Signal Model ü ü ü Right-handed neutrino is light and stable. Coupling of W’ to fermions is the same as for W No mixing between W’ and the other gauge bosons. Decay channels W’ to WZ is suppressed Decay width of W’ scales with its mass. l Production and Decay ü W’ can be production in both ppbar and pp collisions through qqbar annihilation ü Decaying to A lepton-neutrino ü Decaying to A quark pair (include tb channel) June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang W’/Z’ SU(2)L X U(1)Y W/Z U(1)EM e n

CDF W’ Search (W’ → electron + MET) p-pbar Collision at 1. 98 Te. V with 5. 3 fb-1 data June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Data Samples l Looking for the excess events over than SM background in high transverse mass region. l Data : Inclusive High Pt electron sample ü 5. 3 fb-1 (taken in Feb. 2002 ~ Jun. 2009 ) with good run ü Level 3 electron trigger path • ELECTRON_CENTRAL_18, ELECTRON 70_L 2_JET, W_NOTRACK l Background and Signal Samples Ø PYTHIA MC samples Ø Multijet Background : from data driven June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Event Selection June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Electron Energy Correction l Using invariant mass of Z to ee sample June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Electron Id. Efficiency l Z →ee Sample used Ø NTT : both electrons passing Tight Cut. Ø NTP : one passing Tight, the other passing Loose Cut l Total Efficiency June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Background Estimation l MC background : Ø W boson : including real electron and MET in final states Ø Z boson : one electron is mis-measured and then produce as MET l Multijet(QCD) background : data-driven method (next page) June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Multijet Background Estimation Data-driven method adopted June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Multijet Background Estimation June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Background and Data Comparisons Good agreement!! June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

The Highest m. T Event Display June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

W’ Signal : cross-section and width l W’ mass = [500, 1300] Ge. V/c 2, ~50 k events for each mass points ü PYTHIA with CTEQ 5 L PDFs l Cross-section and width June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang l W’ → tb l Br(ele. +neu. ) : ~ 8. 4 %

W’ : generated mass distribution l Before event selection (from PYTHIA generated information) Tails : very heavy input( W’ mass) made large of tail in low mass region June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

W’ : PDF Influence (low tails) ü PDF heavily suppress high mass production region due to limitation of parton energy carried by quarks in Tevatron energy and this is also reported by D 0 [PRL 100, 031804] June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

W’ : MC Acceptance X Efficiency ü Electron and MET > 25 Ge. V cut : due to the low tails in generation ü The efficiency of the other cuts are flat as a function of W’ mass June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

W’ signal and background June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Search W’ : Mt fitting l Search for excess in the m. T dist. over SM backgrounds Ø Variable Binned maximum likelihood method Ø Use Poisson probability with a Gaussian constraining on multijet bg June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Mt Fitting Result l Good agreement between the data and background expectation ü No statistically significant excess observed for W’ and we set the mass limit for W’ June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Systematic Uncertainties l Total Uncertainties Ø PDF : ü weighting method Ø ISR/FSR : ü changing PYTHIA parameters Ø Electron Energy Correction : ü 1% asigned Ø Jet Energy Correction : ü MET is re-corrected with JES ±σ Ø Multijet background : ü calculated with variable electron and qcd samples Ø Cross section : ü weighting method June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

CDF W’ → electron+MET : Limits l Bayesian 95% CL limit calculated l both the shape and rate systematic uncertainties are incorporated l 1000 times pseudo experiment is performed for Expected Limits. ü Used random generated events from the background expectation. June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

CMS W’ Search p-p Collision at 7 Te. V with 36 pb-1 data June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Event Selection l Preselection ü Good primary vertex ü At least 1 electron with ET > 25 Ge. V and H/E < 0. 1 l Used MET from particle flow algorithm l Single electron trigger path l 1 good high p. T electron (HEEP) l Requirement : June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Background Estimation l Need to determine both the shape and normalization of the transverse mass. ü W → ele + neu. : Shape from MC, yield from data-driven (fit of ET/MET method) ü QCD multijet : Data-Driven Method ü The other backgrounds from MC background shape normalization W → e + nu MC Fit of ET/MET multijet Non-isolated electron from Data Fit of ET/MET Other backgrounds MC MC June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

W and QCD Background (Fit of ET/MET) l In two body decay, the energy of the neutrino and electron are expected to be mostly balanced in the transverse plane, and then the ratio of ET is around 1 MT distributions normalized to the region 0. 4 < ET/MET < 1. 5 June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Background and Data Comparisons June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Transverse Mass distributions Good agreement in both background prediction and observed data in the MT distribution(left) and the cumulative distribution(right) June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

The highest MT Event Display June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Systematic Uncertainties June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Number of Event * Other background : gamma+Jet , W→μν, Drell-Yan, WW, WZ, ZZ, single top * Table includes both statistical and systematic uncertainties added in quadrature (does not include lumi uncertainty) June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

CMS W’ → ele+MET : Limits Ø Bayesian 95% CL limit calculator. Ø Cut-and-Count Method, cut point (> 0. 5 Te. V)from the best expected limit. June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Summary/Current W’ Limits ü m. W’ > 1. 12 Te. V/c 2 (5. 3 fb-1@CDF; W’ → electron + neutrino) [PRDRev. D. 83. 031102] ü m. W’ > 1. 49 Te. V/c 2 (36 pb-1@ATLAS; W’ → electron/muon + neutrino) [ar. Xiv: 1103. 1391] ü m. W’ > 1. 58 Te. V/c 2 (36 pb-1@CMS; W’ → electron/muon + neutrino) [ar. Xiv: 1103. 0030] June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Thank you June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

backup June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Summary l For search results on heavy gauge boson, W’ decaying to an electron-neutrino pair, found no statistically significant excess observed in 5. 3 fb-1 of data l Set the W’ boson mass limit with m. W’ > 1. 12 Te. V/c 2 @95% CL , assuming manifest left-right symmetric model ü Publication June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

Tevatron l Proton-anti. Proton colliding with center of mass 1. 96 Te. V This analysis June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang

CDF Detector l Tracking System ü Silicon Detector ü Central Outer Tracker ü 1. 4 T B-field = -1 l Calorimeter ü Electro. Magnetic ü Hadron = -2 l Muon Detection l Trigger System June 04, 2011, PPP 9, NCU, Taiwan, Yuchul Yang ü Level 3 (25000/300/100 Hz) ü High p. T Lepton ü Missing ET ü Jets