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THE LHC/LC SYNERGY

S. Dawson, BNL

December, 2002

- Why we need both the LC and the LHC
- Examples: EWSB, SUSY, top quark
- The cosmological connection

Why are we here?

- Notto compare/ contrast LHC/LC
- Rather to see how physics info from one machine can influence physics results from the other
- Goal: Working group document, Spring 03

Weiglein, Oreglia

What do we want to know?

- What is the origin of EWSB?
- Is it a Higgs?
- Is it something else?
- What is the origin of fermion masses?
- Understanding the top quark
- Is there physics at an intermediate scale? (and what is the scale?)
- Is it SUSY?
- Is it little Higgs?
- Is it extra dimensions?
- …..

Is mass due to a Higgs boson?

Precision measurements:

- Production rates at LEP, Tevatron, LHC fixed in terms of mass
- Direct search limit from LEP
- Higgs contributions to precision measurements calculable

G. Mylett, Moriond02

How do we verify role in EWSB?

Measure Yukawa couplings

Measure spin/parity

Reconstruct Higgs potential

Is it a Higgs?LHC measures B

Eg, ggh depends on ggh and h couplings

Result is combination of coupling constants

Significant PDF uncertainties

Cancel in ratios

Weak boson fusion depends on SU(2) assumption about WWh and ZZh couplings

Precision measurement for Mh>140 GeV from WBF

Higgs properties at LHCZeppenfeld, Belyaev, Reina

Mh<140 GeV, H/H10-20%

Not all channels possible

tth, h+- critical

Higgs Measurements at LHC200 fb-1

300 fb-1

(tth,h, Wh,hbb)

Belyaev & Reina, hep-ph/0205270

PDF uncertainties cancel in ratios

Improved precision by fixing bbh/h coupling to SM value

Note lousy precision on bbh

Theory systematic error:

20% (ggh)

5% (WBF)

10% (pptth)

Untangle Higgs Couplings200 fb-1

Belyaev & Reina, hep-ph/0205270

Well determined initial state

Precision masses with recoil technique

Higgs mass independent of Higgs decay

Model independent Higgs BRs

Van Kooten

Coupling Constant Measurements at LC

LC

Compare LHC:

gbbh40-50%

WBF, 600 fb-1

gbbh 10-20%

Piccinini & Polosa, hep-ph/0211170

At LC, largest uncertainty is theory from mb!

L=500 fb-1, s=350 GeV

Battaglia & Desch,

hep-ph/0101165

Who cares about Higgs Couplings?And how well do we need to do?

- SUSY models, gbbh enhanced at large tan , small MA …info about SUSY parameters
- Little Higgs, topcolor models, new physics in gtth

Logan

LC:

LHC:

Direct reconstruction of

LC @ 350 Gev

Higgs mass measurementsPrimarily interesting for comparison with precision EW measurements

Conway, hep-ph/0203206

Angular correlations of decay products distinguish scalar/pseudoscalar

Threshold behavior measures spin

Higgs spin/parity in e+e-Zh[20 fb-1 /point]

Miller, hep-ph/0102023

Higgs self couplings difficult at LHC

gghhW+W-W+W-(jjl)(jjl)

ghhh=Mh2/2v

Baur, Plehn, Rainwater, hep-ph/021124

Must measure

e+e- Zhh

Small rate

.2 fb for Mh=120 GeV large background

Large effects in SUSY

Resonances

ghhh suppressed MA < 300 GeV

Measuring Higgs Self Couplings at LCCastanier, Gay, Lutz, Orloff, hep-ph/0101028

Lafaye, hep-ph/0002238

Is the world Supersymmetric?

Find SUSY particles

Find SUSY partners

Check impact on precision measurements

Measure SUSY couplings

Reconstruct underlying GUT theory

SUSY predicts light Higgs, Mh<130 GeV

For MA, SUSY Higgs sector looks like SM

Can we tell them apart?

Higgs BR are different in SUSY

Find all SUSY Higgs

Light SUSY consistent with Precision Measurementse+e- H+H-, H0A0

Observable to MH=460 GeV

at s=1 TeV

e+e- H+,H+tb

L=1000 fb-1, s=500 GeV,

3 signal for MH 250 GeV

e+e- W+H-

Largest at low tan

s=500 GeV, .01 fb

Moretti, hep-ph/0209210

Into the wedgeLogan & Su, hep-ph/0206135

mSUGRA simplest version of SUSY

- 4 parameters, 1 sign
- m0 (scalar mass at MGUT)
- m1/2 (gaugino mass at MGUT)
- A0 (mixing term)
- tan (ratio of Higgs VEVs)

Measure m(gluino) at LHC

predict m(neutralino) at LC

Very predictive…all masses and couplings predicted

Relationships are different for GMSB, AMSB…..

SUSY mass differences from cascade decays;eg

M0 limits extraction of other masses

Fit to SUGRA parameters

LHC/Tevatron will find SUSYBaer

Catania, CMS

Chargino pair production, S-wave

Rises steeply near threshold

This example:

LC makes precision mass measurementsHow do we distinguish a chargino from a 4th generation lepton?

Feng, hep-ph/0210390

Blair, hep-ph/99910416

LC can step through Energy Thresholds Run-time Scenario for L=1000 fb-1

- SUSY masses to .2-.5 GeV from sparticle threshold scans
- M0/M0 7% (Combine with LHC data)
- 445 fb-1 at s=450-500 GeV
- 180 fb-1 at s=320-350 GeV (Optimal for Higgs BRs)
- Higgs mass and couplings measured, gbbh1.5%
- Top mass and width measured, Mt150 GeV

Battaglia, hep-ph/0201177

LHC: Fits to SUSY Parameters

LHC: Mass reconstruction limited by LSP mass

LHC sensitive to mass

differences

Bachacou, Hinchliffe, Paige, hep-ph/9907518

LC accuracy

Measurement of LSP mass

at LC improves LHC

mass resolution

SUSY: LC+LHC

- LHC sensitive to heavy squarks
- Use neutralino mass, couplings from LC
- CMS study:10 fb-1 gives squark, gluino masses to 1-2% if neutralino mass known from LC

R. Van Kooten: “Bands, not blobs”

LC measures chargino, neutralino, selectron masses from thresholds

LC extracts mixing parameters from cross section measurements

LHC measures gluino, squark masses

RGE evolve parameters to GUT scale

Sample mass measurements

(SPS#1A):

LC:

LHC:

Combine LC/LHC mass measurementsWindow to high scales?Compare rates at NLO:

Lowest order,

Super-oblique corrections sensitive to higher scales

Masses from endpoints

Assume

Tests coupling to 1% with 20 fb-1

SUSY Couplings:Feng

Probes mechanism of SUSY breaking

Are we being too simplistic?

- Many possibilities beyond MSSM
- Suppose explicit CP violation
- Complex tri-linear mixing
- Instead of h,H, and A

3 states which mix

- Holes in LEP limits on Higgs search
- New phenomenology

Carena, Mrenna

LC/LHC can give insight into origin of dark matter

SUSY provides dark matter candidate, LSP

LSP is weakly interacting, neutral and stable

Cosmic ConnectionsmSUGRA predicts everything in terms of 5 parameters

Calculate 0 relic density

Assume 2 around central value

Assume Dark Matter is 0

Forbidden by 3 g-2

.07 <Xh2<.21

Requires

m1/2>300-400 GeV

M(+)>240 GeV

M(o)>120 GeV

Arnowitt and Dutta, hep-ph/0204187

CLEO bound from bs

Similar allowed region from dark matter

Does this picture persist for more complicated SUSY models?

Dark Matter at large tan 1.8 x 10-4<B(bs)

<4.5 x 10-4

Understanding the Top Quark

- Why is Mtv/2 ?
- Kinematic reconstruction of tt threshold gives pole mass at LC
- Compare LHC

2Mt (GeV)

Groote , Yakovlov, hep-ph/0012237

QCD effects well understood

NNLO ~20% scale uncertainty

Precision Mt, MW test consistency of SM

Limits Higgs mass, SUSY parameters

Who cares about precision Mt? tth coupling sensitive to strong dynamics

Above tth threshold

e+etth

Theoretically clean

s=700 GeV, L=1000 fb-1

Large scale dependence in tth rate at LHC

L=300 fb-1

Top Yukawa coupling tests modelsBaer, Dawson, Reina, hep-ph/9906419

Juste, Merino, hep-ph/9910301

Reina, Dawson, Orr, Wackeroth, hep-ph/0211438

Beenacker, hep-ph/0107081

Still have to understand MW, precision measurements

Fit to S, T0

Without Higgs, effective theory

For new physics at 3 TeV scale, EW fits give a,b1

Models which satisfy EW constraints without Higgs tend to have new Z’ or light t’s

What if the LHC doesn’t find a Higgs????Bagger, Falk, & Schwartz, hep-ph/9908327

Hill & Simmons, hep-ph/0203079

Exciting physics ahead

- LHC/Tevatron finds Higgs

LC makes precision measurements of

couplings to determine underlying model

- LHC finds evidence for SUSY, measures mass differences

LC untangles spectrum, finds sleptons

LHC/LC combination makes precision

measurements of couplings and masses;

Untangles GUT theory

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