PerspectivesS. Dawson, BNL

Science Timeline

Tevatron LHC LHC Upgrade LC

2004 2007 2012 2015?

This is the decade of the hadron colliders!

Physics landscape changes in 2007

Process 10 fb-1 at LHC Previous experiments

We 108 107 Tevatron

Ze+e- 107 107 LEP

tt 107 104 Tevatron

bb 1012-1013 109 B factories

Higgs, Mh=130 GeV

105 ?

gg, m=1 TeV 104 --

Event Rates:

-

-

Poised on the edge of discovery

• Rich physics menu– New physics searches– Precision measurements– QCD: jets, precision

measurements– t,b,c physics– …….

LHC progress

Tevatron progress

LEPII/SLD/Tevatron Precision Tests

• In general spectacular agreement with SM

• Fits redone with new mt

• Only high Q2 data included in 2004 fits

• 2003: 2/dof=25.5/15 (4.4%)– Without NuTev: 2/dof=16.7/14 (27.3%)

– MW=80.426.034 GeV W=2.139 .06 9 GeV

• 2004: New Mw, w, Mt

Electroweak precision tests support SM!

Hard to explain sin2efflept

(not a new puzzle)

LEP EWWG, 2004

Measurements from leptons and hadrons tend to disagree

2 most precise measurements differ by 2.9

Modify Zbb vertex?

Hard to do consistently

Afb0b =(3/4)AeAb

Interpreting sin2efflept

LEPP EWWG 04

sin2efflept from leptons:

•Al(SLD) .23098.00026

•Mh conflicts with direct Higgs search limit

sin2efflept from hadrons:

•Afb0,b(LEP) .23212.00029

•Conflicts with MW measurement

New CDF/D0 Combined Top Quark Mass

Combination of Run I results:

Combination dominated by D0 lepton + jets result

CDF/D0 hep-ex/0404010

Good fit:

63% probability

Mt=178.04.3 GeV

Run II top masses arriving

daily!

Why is the top quark mass so important?

• In QED, running of at scale not affected by heavy quarks with mq>>

• Decoupling theorem: diagrams with heavy virtual particles don’t contribute at scales << mq if – Couplings don’t grow with mq – Gauge theory with heavy quark removed is still

renormalizable• Spontaneously broken SU(2) x U(1) theory violates both

conditions– Longitudinal modes of gauge bosons grow with mass

– Theory without top quark is not renormalizable• Effects from top quark grow with mt

2

Expect mt to have large effect on precision observables

Precision measurements limit Higgs Mass

• Old:– Mt=1745.1 GeV– Mh=96+60

-38 GeV– Mh < 219 (95% cl)

• New:– Mt=1784.3 GeV– Mh=117+67

-45 GeV– Mh < 251 (95% cl)

NEW

Best fit not in region excluded from direct searches

Editorial Comment

• Why do we care if Higgs mass limit goes up?

• 200 GeV Higgs is very different from 120 Gev Higgs

Look for

Look for WW

MW(exp) is a little high?

• Fit precision measurements (include Mt)– MW(fit)=80.386.023 GeV

LEP EWWG 2004

World Average 2003:

MW=80.426 .034 GeV

No deviations from SM at LEP2

LEP EWWG, hep-ex/0312023

Experimental evidence for unitarity cancellations

No evidence for Non-SM 3 gauge boson vertices

What about low Q2 data?

• Moller Scattering

• NuTeV

• Atomic Parity Violation

• (g-2)

Erler and Ramsey-Musolf, hep-ph/0404291

Low Q2 data tests understanding of scale dependence

Low Q2 Data is Window to High Energy

How do coupling constants evolve with energy?

SM

How do masses evolve with energy?

Scalar m2 of MSSM

Allanach, hep-ph/0403133

NuTeV

• NuTeV

• Global fit:

• Understanding of theory error critical

GeV

M

GeV

GeVM

syststat

ht

w

150ln00032.0

)50(

)175(00022.0

)(0009.0)(0013.02277.0sin

2

22

2

0004.02227.0sin 2 w

3 discrepancy?

Experimental Observables Theory Calculation

More NuTeV• Intense theoretical effort• NuTeV analysis related to Paschos-Wolfenstein ratio:

• Non-isoscalar target

– Positive [S-] goes towards removing discrepancy

– CTEQ fit to [S-]=0.002 explains 1.5 of discrepancy– CTEQ: -.005 < sin2W<.004

• Higher order O() electroweak corrections– Apparent discrepancy with older results used by NuTeV– Factorization scheme dependence and treatment of final state photons can account for 3

difference

EWQCDAW

CCCC

NCNC RRRR

2sin

2

1

Q

SR Ws 2sin

6

7

2

1

Kretzer, hep-ph/0405221

Diener, Dittmaier, Hollik, hep-ph/0310364

dxxsxsxS )()(

Only Experimentalists can tell for sure

Atomic Parity Violation

• 2002 fit showed at 1.5 deviation for atomic parity violation (weak charge of Cesium nucleus)

• New calculation of QED corrections• QW(exp)=-72.84 0.29(exp) .36(th)

– Kuchiev&Flambaum, hep-ph/0305053

• Good agreement with best fit value• QW(fit)=-72.880 0.003

Moller Scattering, E158

Purely leptonic reaction

gee ~ 1 - 4sin2W

eff

WbremF

PV Fyy

yQGA

2

44

2

sin4111

1

24

sin2 W(Q2=0.026 GeV2) =

0.2379 ± 0.0016 (stat) ±0.0013 (syst)

Run I + Run II :

Theory:

sin2 W(Q2=0.026 GeV2) = 0.2385 ± 0.0006 (theory)

Extrapolate to MZ

(g-2)

g-2 collaboration, hep-ph/0401008

e+e- data: 2.7 effect

data: 1.4 effect

•Stimulated new theoretical efforts (SM and beyond)

•No evidence for CPT violation

• Progress in understanding hadronic contributions

•Naturally explained by SUSY

2004

11exp

211

10300

tan~100

10150

SMaa

m

GeVa

Contributions to (g-2)

Dominated by low energy region, ρ resonanceP. Gambino, Summer 2003

Hadronic Contributions

Hagiwara et al with e+e- data:

aμhad,LO=691.7±5.8exp±2.0r.c.

Final CMD-2 π π data (2002) 0.6% syst error!

This translates to a ~2-2.5σ discrepancy

Tau data below 1.8GeVTau data below 1.8GeV

Using τ data below 1.8 GeV Davier at al:

aμhad,LO=709.0±5.1exp±1.2r.c±2.8SU(2)

Hagiwara et al, hep-ph/0312250

Davier et al, hep-ex/0312065

τ data consistent with SM

More news on hadronic contributions(Spring, 2004)

Updated light by light

•Understanding of chiral logs

a=56 x 10-11

Updated QED

•Coefficient of (/)4 changed

a=13.7 x 10-11

Melnikov &Vainshtein, hep-ph/0312226

Kinoshita&Nio, hep-ph/0402206

K++

BNL E949: 3 events

BR(exp)=1.47+1.30-0.89 x 10-10

BR(th)=7.81.2 x 10-11

SM prediction updated with new Mt

Buras, Schwab, Uhlig, hep-ph/0405132

E949, hep-ph/0403036

Electroweak physics is in even better shape this year than last

year….

Tevatron is becoming our next precision tool for QCD and EW physics

Tevatron Run II

• Electroweak physics : W, Z’s have large cross sections high statistics, precision measurements– W, Z masses, widths, , W

helicity – Gauge boson pair production New physics effects s/2

• Many new results appearing– Higgs searches– More top, Single top soon– New physics searches– B physics– QCD

M. Kruse, 2004 FNAL User’s Mrg

Tevatron Rates

New Calculational Techniques

• Strong coupling not small s(MZ).12 15em

– Multi-particle states important– Large effects from higher order corrections– Large logarithms from varied scales, log(pT

2/M2)

• Precision measurements require new tools and new understanding– Automation of higher order corrections

• Many processes now calculated at NNLO– We have NNLO distributions

New Data New Calculations

Theoretical Progress in QCD

• Distributions at NNLO

• Theory goes hand in hand with Tevatron measurements– Example: Drell Yan Rapidity to NNLO

– Good stability of answer Predictions to 1%

– Supports idea of using W and Z production to constrain parton distributions

Anastasiou, Dixon, Melnikov, Petrellio, hep-ph/0309264

Tevatron predictions at NLO & NNLO

Data and Theory nicely matched!

W&Z Production Top Production

hep-ex/0205019

Top Quark Physics Major Focus of Tevatron

• Measure single top, ’s, BRs, W helicity, rare decays, spin, heavy particles decaying to tt,…..

Single top not seen

3 pb

CDF, hep-ex/0404036

•Top quark plays leading role in dynamical symmetry breaking models, other new physics models

Goal:

Coming soon:

Need Monte Carlos which include NLO properly

• Match NLO with parton shower

• Subtract terms which are included in parton shower from NLO result

– At high pT, NLO

– At low pT, MC

pptt at LHC

Frixione, Nason & Webber, hep-ph/0305252

Campbell, Ellis

MC@NLO

MCFM

Hadronic B Cross Sections

• Run I b ’s 3 X’s higher than theory

• Theoretical advances: NLL resummations, non- perturbative fragmentation function from LEP, new factorization schemes…

Cacciari, Frixione, Mangano, Nason, Ridolfi, hep-ph/0312132

Still room for surprises

Observation of X

Higgs is hard at the Tevatron

WW channel new SUSY with large tan , dominant production is with b’s

D0 search: tag 3 b’s

QCD and Electroweak Physics at the Tevatron look in good shape too

Tevatron will give us precision map of third generation of quarks!

Given the success of the SM, why are we so certain there is something new at 1 TeV?

• SM with light Higgs in very good shape• But the arguments for new physics at the TeV scale have

never been stronger– Naturalness

• Why is MW << Mpl?

– Dark Matter• What is it? Why is there so much of it?

– Neutrino masses• Where do they come from? Why are they so small?

– WW scattering needs mechanism to restore unitarity • Light Higgs? Something else?

?

2

22222

2

2

GeV200TeV 0.7

123624

thZWF

h MMMMG

M

Mh 200 GeV requires large cancellations…..Used as argument for new physics at the TeV scale

Light Scalars are Unnatural

• Higgs mass depends sensitively on physics at higher scales,

h h

EW data limit new physics at TEV Scale

• Try to add new physics with dimension 6 operators

• Precision measurements already limit > 5-10 TeV

• Flavor violating couplings even more tightly constrained

ii O

cL

2

“Little Hierarchy Problem”

Giudice

llee

bbee 55

BWHH a )(

> 4.5 – 6 TeV

> 3 – 4 TeV

> 10 TeV

Hard to get new physics at the TeV Scale

Much Activity in EW Scale Model Building

• Remove Higgs completely– Dynamical symmetry breaking– Higgsless models in extra D

• Lower cut-off scale– Large extra dimensions

• Force cancellations– SUSY– Little Higgs– Make Higgs component of gauge field

in extra D

Symmetries maintain cancellations at higher order!

Ultimate answer will come from data!

Strong limits from precision

measurements

SUSY….Our favorite model

• Quadratic contributions to Higgs mass cancelled automatically if SUSY particles at TeV scale

• Cancellation result of supersymmetry, so happens at every order

)((....) 2~

222ttFh MMGM

t~t

MSSM requires light Higgs

• Tension: stop should be TeV scale to cancel quadratic contributions to Mh from top loops

• Stop needs to be heavy so that lightest Higgs mass satisfies LEP bound,

Mh>114 GeV• Reasonable to consider

expanding model by adding Higgs triplets and singlets

Degrassi,Heinemeyer, Holliuk, Slavich, Weiglein, hep-ph/0212020

tan=3

Xt=At-cot

...~

lnsin2

32cos 2

2

22

4222

t

ttFZh

m

mmGMM

LEP MSSM Higgs Bound

•Boundaries of theoretically inaccessible region (“the nose”) have shifted due to 2- loop calculations of MSSM Higgs mass

With Mt=179 GeV, tan exclusion disappears!

Is allowed parameter space

unnaturally squeezed?

Beyond the MSSM (NMSSM)

• Add singlet Higgs (doesn’t spoil gauge unification)

V = 2|H1 H2 – v2|2

• Mh ~ v instead of MZ

• Higgs sector very different than MSSM: – 3 Neutral Higgs, 2 pseudoscalar Higgs

• Many scenarios have h0, A at EW scale

• finite to GUT-scale, Mh < 150 GeV

321 3

SHSHWS

Don’t let your imagination be limited by the

MSSM

Little Higgs Models

• G[SU(2)xU(1)]2 SU(2) x U(1)

Global Gauged SM

• Higgs is pseudo-Goldstone boson of G– Symmetry forbids Higgs mass to 2-loops

– Higgs naturally light

• Quadratic contributions to Higgs mass cancelled by new W,Z,, new scalars, & new charge 2/3 fermions

• Large corrections to precision measurements– Hard to arrange for new physics at TeV scale;

must carefully tune parameters

Clear signatures

Arkani-Hamed, Cohen, Katz, Nelson, Georgi, Gregoire, Wacker, Low, Skiba, Smith, Kaplan, Schmaltz, Chang, Wacker, Terning, Hewett, Petriello, Rizzo, Csaki, Hubisz, Kirbs, Meade, Casalbuoni, Deandrea, Oertel, Kilian, , Reuter, Han, Logan, McElrath, Wang Chen& Dawson, hep-ph/0311032

What if no light Higgs?

• Excluded by EW fits?

• Must confront unitarity violation

• What about Higgsless models with EW symmetry broken by boundary conditions?

– Unitarize scattering amplitudes by exchange of new heavy W and Z bosons

– Need mechanism with positive T

LEP EWWG 2004

Models without Higgs have difficulties with Unitarity

• Without Higgs, W-boson scattering grows with energy

A~GFs

– Violates unitarity at 1.8TeV

• SM Higgs has just the right couplings to restore unitarity

• Extra D models have infinite tower of Kaluza-Klein states

• Need cancellations both in s and s2 contributions to amplitudes

• Arrange couplings to make this happen

Look for heavy gauge bosons

Higgsless phenomenology

• Tower of KK vector bosons

– Can be produced at LHC, e+e–

– WW scattering becomes strong

• Tension between:

– Unitarity wants light KK

– precision EW wants heavy KK

Foadi, Gopalakrishna, Schmidt, hep-ph/0312324

J=0 partial wave for WW scattering

Heavier heavier KK

gauge bosonsDavoudiasl, Hewett, Lillie, Rizzo, hep-ph/0312193

Dark Matter points to TeV Scale

• 23% of universe is cold dark matter

• WMAP (and others): Cosmology is a precision science Implications for particle

physics!

Cold dark matter at the TeV Scale

• SUSY models have natural dark matter candidate

• Lightest SUSY Particle (LSP) is neutral and weakly interacting

• On general grounds, LSP contributes correct relic density if mass is 300 GeV-1 TeV

Ellis, Olive, Santoso, & Spanos, hep-ph/0303043

Pink is (g-2) assuming e+e- solution for hadronic contributipn

Blue is dark matter preferred region

Even small region where LC is sensitive to SUSY and LHC isn’t

CDM preferred region will be probed by LHC

Baer, Krupovnickas, Tata, hep-ph/0405058

Conclusions

• Exciting energy frontier physics at the Tevatron and LHC– New Physics searches– Electroweak measurements, W,Z,t– Di-boson production– B and charm physics– Jets

• Guided by low energy precision data– Z pole physics, (g-2), B factories….

• Also by theory– Advances in QCD; new tools– Lots of model building