Andrey Korytov, University of Florida SUSY’08, 16 June 2008, Seoul 1 Higgs Search at LHC (and LHC/CMS status) Andrey Korytov (for ATLAS and CMS Collaborations)

Andrey Korytov, University of Florida SUSY’08, 16 June 2008, Seoul 1

Higgs Search at LHC(and LHC/CMS status)

Andrey Korytov

(for ATLAS and CMS Collaborations)

MUON CHAMBERSBARREL & ENDCAP

SILICON TRACKERFORWARD

CALORIMETER

TOTAL WEIGHT 12,500 tonOVERALL DIAMETER 15 mOVERALL LENGTH 22 m

SUPERCONDUCTING SOLENOID

RETURN YOKE

ELECTROMAGNETIC CALORIMETER

HADRONCALORIMETER

proton beam

proton beam



CALORIMETER



RETURN YOKE


HADRONCALORIMETER

proton beam

proton beam

ATLAS CMS


Outline

• LHC status

• CMS Experiment status

• Standard Model Higgs boson• MSSM Higgs bosons


LHC status and plansLHC status and plans


LHC status

• LHC sectors are being cooled down

the last sector “45” will be at ~2K in July

• Some magnets need

additional training to reach Bmax

• To have the beam this year,

LHC will start out at 10 TeV

(no additional training needed)

• Magnets will be re-trained during

winter shutdown to allow for

the 2009 run at 14 TeV

T~2K, ready for “cold tests”, commissioning, and beam


LHC plan for 2008-2009

2008• beam commissioning Aug-Oct

• center-of-mass energy 10 TeV (some magnets need further training)

• peak luminosity 51031 cm-2s-1

• physics run 40 days (Oct-Nov)

• overall efficiency* 0.1 (based on the 1st year of LEP1)

• integrated luminosity 20 pb-1 (delivered for physics)

2009• center-of-mass energy 14 TeV

• peak luminosity 1033 cm-2s-1

• physics run 150 days (May-Nov)

• overall efficiency* 0.2 (based on subsequent years of LEP1)

• integrated luminosity 2.5 fb-1 (delivered for physics)


CMS commissioning statusCMS commissioning status




CALORIMETER



RETURN YOKE


HADRONCALORIMETER

proton beam

proton beam



CALORIMETER



RETURN YOKE


HADRONCALORIMETER

proton beam

proton beam

CMS experiment status

Muon System

Solenoid

Hadron Calorimeters

EM Calorimeter

Tracker


CMS Magnet

Parameters:• superconducting• 4 Tesla• diameter 6 m• length 13 m• stored energy 2.6 GJ• 64 Bar Radial Pressure

Status:• fully tested while still on surface• cold and ready to be energized • initial field will be 3.8 T


CMS Tracker

Parameters:• coverage ||<2.5• diameter 2.2 m, length 6 m• 220 m2 sensitive area

(more than all HEP experiments combined)• Strips: 11M channels (cf. CDF <1M)

20-80 m precision measurements• Pixels: 66M channels

15 m precision measurements

Status:

• Strip Detector: fully commissioned on surface (good strips ~99.9%)

installed to be operational by mid-July

• Pixel Detector: ready for installation in June


EM Calorimeter

2.8% 12%/ ~ 0.3%

( )( )E E

E GeVE GeV

Parameters:• barrel + endcaps: ||<2.5

• 76K PbWO4 crystals and readout channels

(more crystals—in volume or number—than in all previous HEP experiments combined)

Status:• barrel: installed, commissioned

pre-calibrated to 2%

• one endcap: to be installed in mid-June

• second endcap: ready by mid-July

(install if LHC schedule allows)


CMS Hadron Calorimeter

Parameters:• barrel/endcap ||<3: copper + scintillator

• forward 3<||<5: steel + quarts fibers

• ~10K channels

Status:• installed, commissioned

• calibrated to 5%

Jet Energy Resolution


CMS Muon System

Parameters:• coverage ||<2.4• Barrel: Drift Tube chambers• Endcap: Cathode Strip Chambers• Resistive Plate Counters throughout• 26,000 m2 sensitive area• 700K readout channels• ~100 m resolution per chamber

Status:• all 100% installed

• DTs: 85% fully commissioned

• CSCs: 50% fully commissioned

• RPCs: 10% fully commissioned

• all to be commissioned by mid-July

Drift Tubes(barrel: 5 wheels)Drift Tubes(barrel: 5 wheels)

CSCs (endcaps: 8 disks)CSCs (endcaps: 8 disks)

RPCs(barrel+endcaps)RPCs(barrel+endcaps)


Cosmic Muon Events in CMS

August 2006on the surface, B=3.8 T

(not all detectors on)

May 2008underground, B=0 T

ECAL

HCAL

HCAL

ECAL

Tracker

MUON

HCAL


Cosmic Ray Muons on surface

Magnet Test and Cosmic Challenge in 2006-07• Magnet reliably operates at 3.8 T

• Fraction of all sub-detectors were operational

• Many million cosmic ray events were collected

• Cosmic ray muons were successfully reconstructed, including their momenta, charge ratio, etc.


Cosmic Ray Muons underground

photograph: one of the endcap

muon system stations

occupancy plot: muon hits

registered in that station


Higgs search prospects

More details are in parallel session talks:SM Higgs boson with ATLAS (Francesco Polci)SM Higgs boson H 2 with CMS (Serguei Ganjour)SM Higgs boson H ZZ(*) and WW(*) with CMS (Sinjini Sen Gupta)SM Higgs boson produced in VBF with ATLAS (Guilherme Hanninger) SM Higgs boson produced in VBF with CMS (Pietro Govoni)SM Higgs boson in associated production mode with ATLAS (Huaqiao Zhang)MSSM Neutral Higgs bosons with ATLAS (Jana Schaarschmidt )MSSM Neutral Higgs A/H 2 and 2 with CMS (Georgios Anagnostou)MSSM Charged Higgs bosons with ATLAS (Christopher Potter)


SM Higgs: what we know from theory

unst

able

vacu

um

New

Ph

ys

ics

En

erg

y S

ca

le

(G

eV

)

103

106

109

101

21

015

101

8

0 200 400 600Higgs mass MH (GeV)

unst

able

vacu

um

New

Ph

ys

ics

En

erg

y S

ca

le

(G

eV

)

103

106

109

101

21

015

101

8

0 200 400 600Higgs mass MH (GeV)

One pseudo-scalar doublet (4 degrees of freedom)

Potential V =

After spontaneous symmetry breaking: • W± and Z acquire masses (3 degrees of freedom)• the last remaining degree of freedom (4-3=1): scalar CP-even Higgs of unknown mass

runs with Q:• small mH at 1-TeV scale at some Q, (Q) < 0 V has no minimum (vacuum breaks loose)• large mH at 1-TeV scale at some Q, (Q) = theory is non-perturbative (theorists retire)• chimney (Q) ~ const due to cancellation of +/- terms (fine tuning)

mass must be within 50-600 TeV range


What we know experimentally: LEP

Direct search at LEP:mH>114.4 GeV @ 95%CL


What we know experimentally: EWK fits

EWK precision data:mH<144 GeV @ 95%CL

Combined with the direct search exclusion <114 GeVmH<182 GeV @ 95%CL


What we know experimentally: Tevatron

projected Lint = 5-7 fb-1

by the end of 2009

Note for the range around mH~160 GeV:

The fact the currently observed limit runs ahead of the expected limit (left plot) makes it less likely to observe a 3-excess later (right plot does not include these effects)


SM Higgs at LHC

Colored cells = { detailed studies available }YES = { discovery in the appropriate range of masses at L<30 fb-1 }

Hbb H H HWW HZZ

inclusive YES YES YES

VBF (qqH) maybe YES YES

W/Z+H

ttH

unce

rtai

ntie

s ~

5-20

%

unce

rtai

ntie

s ~

few

%


Forerunners: analyses to see the Higgs first

2003

K factors included

2006

mass ~120 ~140 ~160 190-600

ATLAS VBF, Hincl., H

VBF, HWW* VBF, HWW

incl., HZZ

CMS incl., H incl., HZZ* incl., HWW

ATLAS is coming up with many major updates now


SM Higgs: H

Backgrounds:• prompt • prompt + jet(brem , )• dijets

CMS-2006 analysis:• cut-based

○ events sorted by “em shower quality”○ kinematics, isolation, M-peak

• optimized○ loose sorting and kinematical cuts○ event-by-event kinematical Likelihood Ratio

with bkgd pdf taken from sidebands, signal pdf from MC

• systematic errors folded in

CMS 2006

ATLAS 2006S=6 @ L=30

mH=130 GeV

CMSNLO cut based (TDR-2006) 6.0

NLO neural net (TDR-2006) 8.2

ATLAS

LO cut based (TDR-1999) 3.9

NLO cut based (2006, stat. err. only) 6.3

NLO likelihood (2006, stat. err. only) 8.7

agre

e


SM Higgs: VBF, H Backgrounds:

• Zjj, tt

ATLAS-2008 analysis:• two forward jets, central jet veto• two leptons (e, , or -jet) and MET• inv. mass m built from l, (l or -jet), and pT

mis in collinear approximation (works quite well, despite multiple neutrinos present)

• now qqH, H is ○ gives significance below 5 (despite including KNLO)○ H is behind H○ ATLAS and CMS now agree

2003

2008

2008H

pTmis


SM Higgs: HWW2l2

Backgrounds:• WW, tt, Wt(b), WZ, ZZ • ggWW (box)

CMS-2006 analysis:• KNLO(pT

WW)

• cuts: ○ e/ kinematics, isolation, jet veto, MET

• counting experiment, no peak• background from a control sample:

○ signal: 12<mll<40 GeV

○ control sample: me>60 GeV

○ reduce syst. errors, but pay stat. penalty

• systematic errors are folded in

2008: updates expected from ATLAS and CMS

Signal Region Control Sample

CMS 2006


SM Higgs: VBF, HWW2l2

Backgrounds:• tt, WWjj, Wt

Old ATLAS Analysis:• 2 high pT leptons + MET• 2 forward jets (b-jet veto)• central jet veto• counting experiment, no peak• background from data:

○ Signal: all cuts○ Control sample: no lepton cuts

• Result: better than inclusive WW


jet

jet

ATLASMH=160 GeVHWWe

Signal Region Control Sample


SM Higgs: HZZ4l Backgrounds:

• ZZ, Zbb, tt

CMS-2006 analysis:• NLO cross sections• ZZ:

○ 4-lepton mass dependent KNLO(m4l), <K>~1.35○ NNLO ggZZ box diagram, ~0.2 wrt LO

• cuts: ○ isolation, vertex, e/ kinematics, m4l peak

• control samples for ZZ background: ○ Z-peak (Z and ZZ production are very similar) - preferred○ sidebands (low statistics, shape is not trivial)

• Data-driven methods to measure○ lepton reconstruction efficiency○ isolation cut efficiency per event○ vertex cut efficiency per event

• full treatment of systematic errors (small effect)

• for a broad search in a 110-600 GeV mass window, the “look elsewhere” effect de-rates significance by about 1 unit


CMS 2006

CMS 2006

H ZZ4


SM Higgs: ttH, Hbb

ttH is (was?) the best bet to see Hbb

CMS 2006L=60 fb-1

ttH, Hbb

currentestimate of

backgrounduncertainties

jet energy scale (3-10%)jet energy resolution (10%)

b/c-tag efficiency (4%)uds/g-tag efficiency (10%)

luminosity (3%)

mH = 120 GeV L = 30 fb-1

2008

mH = 120 GeV L = 30 fb-1

2008

Early projections: might be observable already at L=30 fb-1

CMS-2006 analysis: • systematic error control at a percent level is needed—not feasible...

ATLAS-2008 analysis:

• same conclusions


Standard Model Higgs: Summary

Benchmark luminosities (CMS+ATLAS):• 0.1 fb-1: exclusion limits will start carving into SM Higgs cross section• 0.5 fb-1: discoveries become possible if MH~160-170 GeV• 5 fb-1: SM Higgs is discovered (or excluded) in full range

NLO cross sectionsSystematic errors included

CMS 2006 ATLAS update should become available this year

CMS+ATLAS will need approximately half-luminosity in comparison to a single experiment


MSSM Higgs: what we know from theory

• One doublet of Higgs pseudo-scalar fields is replaced with two○ one couples to up-fermions and has vev=vu

○ the other to down-fermions and has vev=vd ○ which allows for cancellation of the higgsino triangular anomaly loops

• 2x4-3=5 physical scalar fields/particles: h, H, A, H±

• properties at tree level○ fully defined by 2 free parameters: mA, tan=vu/vd

○ CP-odd A - never couples to Z and W:- decays: bb, (and tt for small tan)

○ CP-even h and H are

- SM-like in vicinity of their mass limits vs mA

- large tan … enhances coupling to “down” fermions: b/ become very important! … suppresses coupling to Z and W

○ H± “strongly” couples to tb and ○ all Higgs bosons are narrow (<10 GeV)


MSSM Higgs: what we know from theory

*Suggested by Carena et al., Eur.Phys.J. C26, 601(2003)

Loop corrections give sensitivity to the rest of SUSY sector Special benchmark points*:

• max stop mixing (mh-max): ○ maximizes mh

○ mh < 133 GeV○ LEP results are least restrictive

• no mixing: ○ opposite extreme to above○ mh < 116 GeV

• gluophobic h ○ ggh production is suppressed

(top+stop loop cancellation)○ mh < 119 GeV

• small eff (mixing of u/d):○ h and bb BR’s are suppressed

even for large tan○ mh < 123 GeV


What we know experimentally: LEP (1)

mh-max scenariomakes LEP resultsleast restrictive

dotted line – expected limitlight green – 99% CL, dark green – 95% CLyellow – theoretically not accessible


What we know experimentally: LEP (2)

mh-max scenariomakes LEP resultsleast restrictive

dotted line – expected limitlight green – 99% CL, dark green – 95% CLyellow – theoretically not accessible

90 GeV


What we know experimentally: Tevatron

tan~40


MSSM Higgs boson: h, H, A production

• x-sections are comparable or larger than SM (dotted line)• bb(h/H/A) production is very important

h H A

h H A

tan=3

tan=30


MSSM Higgs: SM-like signatures

CMS-2006:• better detector simulation

• systematic errors included

• contours recessed w.r.t. earlier projections

ATLAS-2003:• no systematics included

• updates are coming out this summer

ATLAS2006


MSSM Higgs: heavy neutral H, A • given the H/A mass degeneracy, they are often referred to as

• production in association with bb (especially good at large tan)

• Decays (large tan):○ bb-decay mode (~90%) is overwhelmed with QCD background○ -decay mode (~10%) is the best bet○ -decays (~0.03%) allow for direct measurement of

bb, bb

signal

bb, bb,

CMS, 60 fb-1

mh-maxmA=600 GeVtan=50

bb, bb

mbb (GeV)


MSSM Higgs: heavy neutral H, A

ATLAS

CMS 2006


MSSM Higgs: Heavy H±

Heavy H± (M>mtop):• production via ggtbH± and gbtH±

○ tjjb○ H± tb (BR~80%) overwhelmed by bkgd ○ H± (BR~20%)

• backgrounds: tt+jets, tW+jets, W+jets

H±tb

CMSH± tb and t(jjb or lb)


MSSM Higgs: Light H±

Light H± (M<mtop):• production via plain qq/ggtt

○ tjjb○ tbH± (depends on mass and tan) H± (BR~100%)-jet (best channel)

• main backgrounds: tt


MSSM Higgs: H± summary

2 2~ A WHM M M


ATLASL=300 fb-1

Combining all together…

MSSM Higgs or SM Higgs?

SM-like h only:• considerable area…• even at L=300 fb-1

Any handles?• measure branching ratios?• decays to SUSY particles?• SUSY particle decays?


MSSM Higgs or SM Higgs?

Decays to SUSY:

• H 22

(l+l-1)+(l+l-1

)

• Signature:○ Four leptons○ Large MET

Msleptons=250 GeVATLAS300 fb-1

BR for different channels: • R = BR(hWW) / BR(h)• =|RMSSM-RSM|/expimental CMS

CMS


MSSM Higgs: other benchmark points?

ATLAS studies (c. 2003):• preliminary (no syst)• all four special points are

well covered at L=30 fb-1

• main workhorse:

SM-like VBF with -decays

• caveat for small eff: decoupling from is compensated by WW enhancement


MSSM Higgs: yet another twist

CP-violation in Higgs sector

• complex couplings:○ mass eigenstates H1, H2, H3 are

mixtures of h, H, A○ production/decay modes change

• new benchmark point CPX (maximum effect) suggested by Carena et al., Phys.Lett B495 (2000) 155

• new parameterization: MH±, tan

• uncovered holes remain• more studies needed

ATLAS preliminary

○ VBF HWW ○ bbH, H○ tbH± and tH±, H±○ …

ATLASL=30 fb-1

not excludedat LEP!


Summary

Standard Model Higgs:• 0.1 fb-1 exclusion limits will start carving into SM Higgs cross section

• 0.5 fb-1 discoveries become possible if MH~160-170 GeV

• 5 fb-1 SM Higgs is discovered (or excluded) in full range

• forerunner search channels: WW, ZZ,

MSSM Higgs:• nearly full (mA, tan)-plane is covered at L~30 fb-1

• forerunner search channels for h, H/A, H±: (assoc’d b/t important)

• there is a serious chance to see only a SM-like Higgs…

Documents

Andrey Korytov, University of Florida SUSY’08, 16 June 2008, Seoul 1 Higgs Search at LHC (and LHC/CMS status) Andrey Korytov (for ATLAS and CMS Collaborations)