Tevatron Searches for Higgsand SUSY

for the and collaborations

Dan Claes

Hadronic Structure 2007September 3-7

Comenius University Study and Congress CenterModra-Harmónia, Slovakia

Searches for contributions to observed events by Higgs decays as well as new phenomena beyond the Standard Model are intensifying as the Tevatron data set grows. CDF

Main Injector & Recycler

Tevatron

Chicago

p source

Booster

p

p

p p

1.96 TeV

CDF

DØ

Proton-antiproton collider operating at COM energy of 1.96 TeV

Collider Run II Peak Luminosity

Collider Run II Integrated Luminosity

Will run for at least two more years!

~3 fb-1 recorded!

All the results shown today are based on analysis

of 1+ fb-1

4-8 fb-1 by 2009

one in ~1012 events could be a

Higgs boson!

have seenevidence for single top!

gg

tt

t

H

W / Z W / Z

H

q

q

Higgs production at the Tevatron

AllowedAllowed

Higgs self-coupling Higgs self-coupling divergesdiverges

unstable vacuumunstable vacuum

Nature appears to respect gauge invariance masslessness

Through electroweak symmetry breaking within the complex scalar field, V(), of the Higgs

the gauge bosons W,Z acquire mass

and a spin-0 Higgs boson appears,its own mass unspecified

though theoretical considerations do constrain it.

mH < 144 GeV at 95% confidence limit

The latest LEP Electroweak Working Group fit yields a preferred value of:

Direct searches reveal mH > 114.4 GeV/c2 at 95% confidence

A Standard Model Higgs should be LIGHT!

Exc

lud

ed a

t E

xclu

ded

at

LE

PL

EP

mH<135 GeV/c2

mH>135 GeV/c2

• produced with W or Z boson• decay to b quark pair

• direct ggH production• decays to W boson pair

bbWH bbZH

bbZH

WWH

Most sensitive searches:

Analysis Strategy

mH < 135 GeV

WH/ZH WH/ZH + + HH bb bb

mH > 135 GeV

Gluon fusionGluon fusion + + HHWWWW

top, Wbb, Zbb

WW, DY, WZ

BackgroundBackground

H->WWbb

electron/muon

Selection - one or two tagged b-jets - e or with p

T > 15 GeV

- ET > 20 GeV

neutrino

DØ: 4 non-overlapping samples - e or with - 1 “tight” or 2 “loose” b-tags

CDF: 2 exclusive samples using different b-tagging algorithms

95/SM = 9.05, 11.1 9.95, 10.1DØ exp, obs CDF exp, obs

Limits set cutting on NN output:

Selection: - two acoplanar jets

(exactly 2 – CDF) - ≥ 1 tagged b-jets (CDF) 2 tagged b-jets (DØ) - E

T > 55 GeV (CDF)

50 GeV (DØ)

b jet

ZH bb

b jet

Backgrounds : - W+heavy flavour jets - Z +heavy flavour jets - top pairs

ZH bb

Selection:-require two isolated muons or electrons in Z mass window-one or two tagged b-jets

e,

Look for enhanced production of Zs:

e,

CDF- corrects its b-jets with ET projections

Separate NN trained to rejecttwo main background processes:

Z + jets top pairs1 ‘tight’ b-tag 2 ‘loose’ b-tags

at MH = 115 GeV

95/SM

20.4 exp 1617.8 obs 16

→ hadrons

→ e or

→ e or

same charge

di-lepton massSelection:- 2 isolated leptons (pT > 15 GeV) (electrons and/or muons)- kinematic likelihood selection

ee

e

“flips”: charge mis-identification estimated from data:: solenoid vs toroide: solenoid vs (track,calorimeter)

like-sign!

, m , ET or E T

min

ee e

expected

background

20.6 4.0

18 5

data 19 15 5

WH(160) 0.1 0.2 0.1

95/SM ~ 18for

MH = 160 GeV

L = 1 fb-1

16

Selection:- two isolated leptons- large ET

miss - Less than 2 jets (>15 GeV) CDF If WW comes from a spin-0 Higgs

Higgs:small ( )

W W:large ( )

leptons will tend to align

Matrix Element Technique

most sensitive at high masses

• Combines sixteen mutually exclusive final states for WH, ZH, WW

- 10.4 SM at mH=115 GeV

- 3.8 SM at mH=160 GeV• Today I’ll report on recent progress

– updated CDF & DZero low & high mass 1+ fb-1 analyses

SUMMER 2006

Combines sixteen mutually exclusive final states for WH, ZH, WW

7.7 SM at mH=115 GeV

1.4 SM at mH=160 GeV

The Standard Model assumes a single complex Higgs doublet generates W/Z masses and a

massive chargeless spin-0 boson, the Higgs, H

Higgs Bosons Beyond the Standard Model

2HDM: 2 Higgs Doublet Models

• Hu/Hd couple to up- and down- type quarks• tan β is the ratio of their vev’s tan β = <Hu>/<Hd>• EWSB results in 4 massive scalar (h, H, H±) and one massive pseudoscalar (A) Higgs bosons ()

Minimal Supersymmetric Model

At large tan enhanced0bb and 0tt couplings

mean large Higgs productionrates at hadron colliders!

• fully parameterized (at tree level) by tanβ, mA

• with radiative corrections that depend on stop mixing

is accessible to the Tevatron provided mH is not too large!

Background rates in 3 final state are very low• measured fake rates for Z or W • tri-photon production extrapolated from di-photon sample

For tan > 1, mH < 200 GeV and mh < 90 GeV

B(h ) 1 and B( H hW ) 1

Fermiophobic Higgs Decaying to 3A production mechanism unique to hadron colliders

Optimizing selection on 3sET > 30, 25, 25 GeV

0 events observed1.1 0.2 expected background

No obvious structure in

diphoton mass spectrum

Optimizing final selection on 3sET > 30, 20, 25 GeV

and pT > 25 GeV rejects background

Process Events

expected direct 3 0.9 0.2

estimated 3 fakes 0.3 0.05

Observed 0

LEP2 limits of 108 GeV/c2 assumed SM coupling hf V V

Fermiophobic Higgs Decaying to 3

Fermiophobic Higgs in 2+ X

XhVVppf

XZWhpp

f )(

1.1 fb-1

Selection: 2 photons (pT > 25 GeV)

mh>92 GeV at 95% CL

Background: , +jet and jet+jet

b (b) bb b(b) Search

g

g

b

b 0

b

gb

0At high tan Br(H/Abb) 90%, but swamped by QCD background

Look for associated production with bs.

Selection:- 3 b-tagged jets- look for a signal in the invariant mass of two leading jets

The shape from double–tagged events ( mis-tagged rate)

Normalized to the

3b-tagged sample outside

the signal mass

window.

ALPGENMC

0.90 fb-1 0.980 fb-1

b (b) bb b(b) Search

CDF found two useful discriminators• m12 (invariant mass, 2 leading jets)

• mdiff = 321 jet

vertex

jet

vertex

jet

vertexMMM

mass of the tracksassigned to jet fromthe displaced vertex

Neutral MSSM Higgs hadMain backgrounds: Z (irreducible),

W+jets, Zee,, mulijet, di-boson

DØ: -channel only

CDF: e, ,e+ channels

• 1 isolated separated from opposite sign hadronic

• isolated e or separated from opposite sign hadronic

• set of 3 NNs discri- minate from jets

• variable-size cone algorithm for

mvis p1

vis p 2

vis p T

• mvis < 20 GeV removes

remaining W background

• T

had

TTTEppH

> 55 GeV

• Ws removed by a cut on the MET projected on the bisector between s.

Neutral MSSM Higgs had

Small excess in CDF’s e+ channel• but < 2 effect• not observed in CDF e channel

While DØ is in good agreement with SM

Neutral MSSM Higgs had

Both experiments give similar results:in the 90<mA<200 GeV region

tan > ~40-60 excludedfor the no-mixing and mh

max benchmarks

~

~

~~

~Particle Name Symbol Spartner Name Symbol gluon g gluino g charged Higgs H+ chargino 1,2

charged weak boson light Higgs h neutralino 1,2,3,4 heavy Higgs Hpseudoscalar Higgs Aneutral weak boson Z photon quark q squark qR,L

lepton l slepton lR,L

SUPERSYMMETRY

0

The Lightest Supersymmetric Particle provides• ET if the LSP is stable and R-parity is conserved• photons and ET if the LSP is a gravitino and NLSP a neutralino• long-lived particles if the LSP decays weakly

SUSY particles are heavy• high pT final state objects

Minimal Supersymmetric SMExtension adding the fewest new particles

• 2 Higgs doublet h0 H0 A0 H+

• and described by 4 parameters M1 U(1) M2 U(2) gaugino mass parameter at EW scalehiggsino mass parametertan ratio of VEV of Higgs doublets

• scalar sector described by MANY mass parameters• different SUSY breaking different class of models

01

~ 1

~

MSSM Assumptions:

• SUSY particles are pair produced• Lightest SUSY particle (LSP) is stable

SLBparityR 23)1(

•Lightest SUSY particle is

• 5 free parameters

mo common scalar massm1/2 common squark massAo trilinear couplingtansign(

01

~

SUSY Symmetry Breaking SUGRA( ~ 10 11 GeV)

with 0 as Lightest Supersymmetric Particle and bWtcmmmMm

01

~~

Search for: 2 charm jets plus Missing ET

Stop charm + ET

R-parity pair production

Pre-selection: 2 jets, pT > 40(20) GeVLepton, track vetosδφ(jj) < 165o

δφmax δφmin < 120o

δφ(j,ET) > 50o

A=(ETHT)/(ETHT)>0.05ET> 60 GeV

01

~~

mmMbtand

then flavor tag (>= 1 jet)

~

*use Zee+jets tonormalize Zvv+jets

SM process Number of events

W l+jets 20.62 2.34 Z +jets *13.23 1.76 W l +HF (bb, cc) 11.94 1.06 Z +HF (bb, cc) 11.60 0.78 WW,WZ,ZZ 2.70 0.27 t t 2.17 0.07 Single top 1.76 0.05 Z ll(e,,)+jets 0.12 0.09Z ll(e,,)+ HF (bb, cc) 0.09 0.04

Total BKG 64.213.22

Data 66

Stop charm + ET

Finally optimize mass-dependent cuts on HT and P = max + min

For GeV 75 GeV, 13501

~~

mmt

HT>140 P<320

Search for Long-lived Stop

Tracking

Chamber

Electromagnetic

Calorimeter (EM)

Muon

Detector

CDF

Hadronic

Calorimeter

TOFA long-lived, charged massive particle (CHAMP) appears as a “slow” muon.

Some models predict long-lived massive particles due to:– weak coupling (e.g., NLSP in SUSY

models with GMSB)– Kinematic constraints (chargino in SUSY

with AMSB)– New symmetry (gluino in split-SUSY,

LSP stop in ED models)

– High PT, low velocity, highly ionizing “muon”

– Measure velocity () via TOF detector + timing from tracking detector– Calculate mass from momentum and

Data

Control Region

dominated by WGeV pGeV

T4020

Signal RegionGeV p

T40

Search for Long-lived Stop

Exclude stable stop with

m<250 GeV/c2 at 95%CL

• Signal region: no candidates with m>120

• consistent with expected background

Prospino2

Squarks/Gluinos jets + ET

Assuming R-partity is conserved, squarks and gluinos can decay directly into the LSP (0

1).

or cascade down to the LSP

The dominant signature for ppqq, qg, gg + X is jets+ET

At least 3 jets ET > 25 GeV and ET > 25 GeV Separate 2-jet, 3-jet and >3-jet analysis.

Squarks/Gluinos jets + ET

Mgluino < 290 for any Mq

Mgluino < 380

excluded for Mg ~ Mq

1.4 fb-1

A0=0tan = 5<0

~ ~

~

Squarks/Gluinos jets + ET

Mgluino < 402 excluded for Mg~Mq

Mgluino < 309 excluded – any Mq

~ ~

~

0.96 fb-1

A0=0tan = 3<0

Squarks had + jets + ET

0

2~χ

τ -

A0 = 2m0

tan = 15 < 0

enhanced decay

Selection:• 2 or more jets ET > 35 GeV

• ET > 75 GeV • at least one hadronic

Optimization: • ET > 175 GeV • > 325 GeV

T

jet

T

jet

TEEE 21

Squarks had + jets + ET

Predicted YieldsSignal (m0,m½)( 80,160) 4.70.4(100,150) 7.10.6Background 1.7 Data 2

LEP2slepton

searches

LEP2charginosearches

Translating to CL mq

%95@GeV/c 366 2~

Chargino/NeutralinoTrileptons

Production of 1 02 will lead to trilepton final states with ET

perhaps the cleanest signature of supersymmetry.

Dominant backgrounds:Dibosons and Drell-Yan withconverting bremsstrahlung photon

ee+track• Limits set on Br as a

function of mass• Results interpretted within select mSUGRA scenarios

~

qmm ~~

021

~~~

mmm ~

Large and Br

Maximal 3

Chargino/NeutralinoTrileptons

DØ ee+track:Final SelectionSignal: 1-2 eventsBackground: 1 0.3Data: 0

DØ Combined Limit (5 analysis) : 107.0)3( pbBr

2

~/140

1

cGeV m

DØ Combined Limit (14 analysis) : 125.0)3( pbBr

2

~/130

1

cGeV m

Conclusions