CCAST Workshop on TeV Physics and the LHC

ITP, Nov. 7, 2006Mike Bisset / 毕楷杰

Co-`workers’:Guan Bian (Tsinghua U.)Nick Kersting, Y. Liu, X. Wang (Sichuan U.)S. Moretti , F. Moortgat (Europe) References:Eur.Phys.J. C45 (2006) 477-492hep-ph/0501157

Beijing, China

Tsinghua University

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清华大学

Recent convergence in Beyond the SM scenarios

Need to avoid constraints from loop contributions to low energy processes and LEP analyses

pair production of new states

Minimal Universal Extra DimensionsKK-parity in

T-parity insome Little Higgs Models

like R-parity in SUSY

ITP 2006.11.7 克隆克隆

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Spectra of new states expected to be quite different in different models

BUT at LHC only a fraction of the entire spectrum may be identified.

One feature of SUSY --- multiple Higgs boson statesmultiple Higgs boson states that may be singly produced in addition to the pair-produced sparticles

(spins also differ)

(spin may be hard to determine at LHC)

ITP 2006.11.7

MSSM with R-parity conservation:

LSP is stable and invisible

01

(-ino for short)ITP 2006.11.7

How well can we do at the LHC?

ITP 2006.11.7

Detecting the lone Higgs Boson of the SStandard MModel

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is a bit more complicated:

Situation in

SUSY MSSM

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only detect h‘‘decouplingdecoupling regime’regime’

the

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BUT depends on good

detection capabilities

for b’s and tau’s

only detect h

LEP II excluded

, ,A H H

signals

ITP 2006.11.7

Depends on good

detection capabilities

for b’s and tau’s

only detect h

, muonsH A

Gold-plated signal

LEP II excluded

ITP 2006.11.7

try harder we must…

……to feel the FORCE as it flows to usto feel the FORCE as it flows to us from the LHC datafrom the LHC data

ITP 2006.11.7

星球大战 ----尤达

Ahh.., but proceeding pictures take into account Higgs boson decays into sparticles

they do not!

0 0 *, , , , ,i j i jh H A 0 ,i jH

On the dark side…decays to these channels reduce the rates of SM signal channels

On the good side…

new signals they may be found

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0 0 0 02 2 1 1, i i j jH A

4 leptons + signatureE

But if such a signal is observed,But if such a signal is observed, is it really from this decay chain?is it really from this decay chain?

(assumption in several studies thus far)

(2 OS same-flavor pairs)

OneOne channel that has received some attention is:

ITP 2006.11.7

Tsinghua University

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0 02 3 0 02 4 0 03 3

0 03 4

0 02 2 1 1 2 2production f f f f E other

stuff

but also

0 04 4

How much of each?Depends on parameters of the model

1 2, are or f f e

CPS2006

ITP 2006.11.7

M

(GeV

)2

tan 5 , BR , 4 inPP H A H A N fb

1 20.5M Mfrom

gauginounification

400AM GeV

500AM GeV

600AM GeV

light sleptons

Ino sector inputs for the MSSM

ITP 2006.11.7

M

(GeV

)2

tan 10 , BR , 4 inPP H A H A N fb 400AM GeV

500AM GeV

600AM GeV

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2M

(G

eV)

tan 20 , BR , 4 inPP H A H A N fb 400AM GeV

500AM GeV

600AM GeV

ITP 2006.11.7

2,M ino parameters 2,Mfavor favor heavier ino pairs

ino parameters0 02 2

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MSSM Point 1

MSSM Point 2

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Plus crucial role for sleptons

CPS2006

,

, , ,L R

L R L Re e

m m

m m m m

, ,eA A A

Rm

MSSM inputs of the slepton sector

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rate enhanced

factor of ~5

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What about in mSUGRA ?

0 02 2

0 02 2non-

region

regionITP 2006.11.7

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Now what about non-Higgs boson ‘backgrounds’?

hello

Now what about non-Higgs boson backgrounds?

SM backgrounds can be eliminated mainly through

TE cut coupled with 4 final state

Other SUSY processes?

CPS2006

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Exactly four isolated, high , low leptons TE ore 2.4 7,4GeVTE

Apply CUTs:

four lepton invariant mass cut

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Need to know Higgs bosons masses

…but this is what we seek to discover!

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MSSM Point 2

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ino parameters

favor0 02 2

2,M

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2,Mino parameters

favor heavier ino pairs

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2,Mino parameters

0 02 2

favor

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2,Mino parameters

favor heavier ino pairs

Can also look for charged Higgs bosons

0 0 01 1i j i i j jt H t t

3 Ttop E signature

2 210M GeV

135GeV

/110 / 210m GeV

/ 800 /1000g qm GeV

Set A :Set A :

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Note that in delineating a discovery region for the Higgs bosons,

we are comparing the Higgs signal

at one point in the MSSM parameter space to MSSM `backgrounds’

at the samethe same point in the MSSM parameter space

Could a Higgs excess

postulated for one point really be due to increased backgrounds at another point?

Consider different ways in MSSM to produce a pair of inos

我

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老毕

未知

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1 1, a b i i j jH A E4 leptons + signature

but restrict ourselves but restrict ourselves to leptons pairs of distinct flavorsto leptons pairs of distinct flavors

(2 OS same-flavor pairs)

ITP 2006.11.7

( , 1)

0 0 stuffi j

p p e e Ei j

Now consider all methods of producing –ino pairs

It turns out that this restriction is not really necessary, but it simplifies the analysis.

other stuff

Ino Pair Production Modes:

‘direct’ Higgs-mediated colored-sparticle cascade decays

Rates generally smaller

Rates may be large if heavier MSSM Higgs bosons

are in the right zone

Largest potential ratesdue to strong production cross-sectionsEspecially if gluinos (and squarks) are relatively light.

0 0 0, (but not )H A h

400 500 GeVgm

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jetty

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At a hadron collider, cannot set energy for the parton-level processunlike at a linear collider where one can scan up incrementally in to cross each threshold sequentially one at a time

e e

cmE0 0i j

0 0i j So just must deal with different states

being produced simultaneously at different rates

Need to disentangle theseITP 2006.11.7

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( )M e e

M

box-like shape0 0i i

0 0i j

for production

wedge-like shapefor production

( )i j

for our process types

ITP 2006.11.7

coin the name `wedgebox plot’

also Z-Line:

01

01

0 ~~~ llZi

decay via off-shell or charged slepton

0*Z

Consider WEDGEBOX PLOTS

eeM

M

01

0 ~~ mmi

01

0 ~~ mmi

01

0 ~~ mmi

01

0 ~~ mm

j

Zm

Zm

BOX (i = j) WEDGE (i != j)

Z-Line:

)~2~~( 01

00 eeji

*On shell sleptons:

2~

2~

2~

2~

~

01

0

0 11l

l

m

m

m

mm

i

i

01

01

0 ~~*~ llZi or0

10 ~*

~~ lllli

01

01

0 ~~~ llZi

ITP 2006.11.7

Possible Wedgebox Plots:

Could be 0 02 2

0 03 3

0 04 4

or

or

ITP 2006.11.7

Complications

Assumes0i e NONO

NONO

other stuff

0

0

i

j

e e

0 stuffi jp p

other stuff

just other stuff (no leptons)

Typically these decay modes are small to negligibly tiny.

Neglects charginosAlong with leptons from decaying top quarks that might happen to be produced.

stuffi jp p stuffi jp p

ITP 2006.11.7

While not yet included in the framework we’ve developed for possible wedgebox plot topologies, we do understand the distributions obtained from such processes fairly well.

& slepton pair production

Tsinghua University

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Gluino/squark pair production with cascade decays

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charginoscharginos!!!

Note: these are inclusive 4-lepton rates with no cuts ore

ITP 2006.11.7

simulate signals and backgrounds

realistic calorimeter simulation package (recent CMS package)

with HERWIG 6.5 event generatorcoupled to

Now actually

From Table can determine relative rates for different –ino pairs

Point C: 22 33 44: : 131.5 :1.3 :1r r r

23 24 34: : 10.2 : 9.6 :1r r r

ITP 2006.11.7

Resulting Wedgebox plots

MSSM Point A

envelope-types

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MSSM Point A

Hard edges

3-body decay0 02 142.8 GeV massdifference

0 02 1( ) 0.245BR

off-shell sleptons very important

ITP 2006.11.7

MSSM Point A

Here sleptons on mass-shell

two-body decays

End points no longer -ino mass differences

0 * 01,i

ITP 2006.11.7

“stripe”

MSSM Point A

Note change in event density around 85 GeV

0 02 3 production

or a 0 0 04 2 1 other

stuff

E22.8% of the time

ITP 2006.11.7

0 02 2 0 03 3 0 04 4

or

or

IIIIIIji ll ,,

00 ~~

03,2

04

~~

1 + 3

02

03

~~

+ 2

+ (2)(3) + 6

+ (2)(6) = 30

How many Wedgebox Plots?

With infininte luminosity, see a 6x6 checkerboard

ITP 2006.11.7

MSSM Point A“maverick events”

These events are not expected within out neutralino-only framework for predicting Wedgebox plots

Study of the detailed HERWIG output for such generated events confirmed that leptons in these events come from charginos

in addition, there were other exceptional features of these points ITP

2006.11.7

MSSM Point B

envelope-types

ITP 2006.11.7

MSSM Point B

Double the luminosity

Two heavy –inos very close in mass

ITP 2006.11.7

MSSM Point B

Note: squark production is required to account for these events

0 02 4

ITP 2006.11.7

MSSM Point C

envelope-types

Try to reconstruct

production rate leptonic BRrates for different –ino pairs

MSSM Point C

from 6 observables:

, , , , ,

Assuming triangular population density distributions:

# of

ev

ents

Point C: 55

55

96

96

173

173

for :44re.g.,

(GeV)

( )M

'sijr

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Fact : rates of getting via direct production are extremely small0 02 2

Next consider the electroweak production processes

Use jet cut to remove cascade decays from gluino/squark pair production (or make colored sparticles very heavy)

ITP 2006.11.7

coupling suppressed

Only one pair combination, can lead to an appreciable rate

(sufficient to adequately populate a wedgebox plot)

Other pairs are too phase-space suppressed

0 02 3

No direct production boxes !!!

2 2

3 4

* *3 3 4 4

| Re2cos

| Re2cos

i i i iW

i j i j i jW

gZ N N

gZ N N N N

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ITP 2006.11.7

0 02 3

0i j

direct

from0 0,A H

i j

chargino chargino pairs

direct

directchargino chargino neutralinopairs

only meaningfulcontributor !!!

Must lose lepton or jets

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MC results: See two islands with rates over 100 events for 1100 fb

ITP 2006.11.7

Separated by `spoiler’ canal

tan 10

Rate Can be Larger

Scanned GeVmGeVl

300120,50tan5 ~ ITP 2006.11.7

tan 10 tan 5 tan 20

02

m m m

canal of Spoiler mode

1300 fbL

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Revised version:

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Comments:

In regions of upper island where double wedge is seen, will be able to extract 3 mass differences with reasonable precision.This will allow determination of the 3 input parameters of the neutralino mixing matrix if the slepton parameter(s) are under control.

2 , , and tanM

0 02 3 Direct production produces a wedge

Slepton pair production also produces wedgesCharginos can produce boxes, but only for low 2 &M

(lower island)

If one observes a box in the experimental wedgebox plot, then either one has seen evidence of a heavier Higgs boson or are both rather small.

2 &M An (almost) parameter-space independent statement.

ConclusionsLet me go!!!

Have shown can extract substantial information on the MSSM –ino mass spectrum

But beware of assuming hard edges = -ino mass differences

Sleptons must also be considered as key playersITP

2006.11.7

Wedgebox plots:

Heavier MSSM Higgs boson search techniques via decays to SM particles inadequate

Full consideration of Higgs boson decays into sparticles makes accessible large new regions of the MSSM parameter space

0 0, :,A H H

A

B

C

Traditional 1-Dim plots2-D

im D

alitz-like p

lots

2-D plots give quick visual impression of which –ino pairs are being significantly produced

Obvious advantages over traditional 1-D plots ITP 2006.11.7

e e Undoubtedly, will still require a ~TeV scale linear collider to fully sort things out and do better precision measurements.

…but that may well take

another years to be realized.ITP 2006.11.7

The topology or pattern of the wedgebox plot maymay tell us where we are in the parameter space and whether or not heavy Higgs bosons are being produced.

Parameter-space dependent cuts may then be applied to purify a sample of 4 lepton events from a specific process.

Potential applicability of this methodology to other beyond the SM scenarios with conserved Q.#’s that demand pair production of a spectrum of new particles

The End

Thank you for listening!!!

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ITP 2006.11.7

MUED’s Minimal universal extra dimensions

All SM fields propagate in a single compactified extra dimension

with compactification radius near the TeV scale

All SM particles have KK partners with similar couplings

The lowest KK level particles carry a conserved quantum numberKK-parity

The lightest KK particle is the stable LKP

The LKP is not detected, resulting in a missing energy signal.

(lowest energy states in the Kaluza-Klein towers)

Sounds a lot like the MSSM, no?

First consider something that is NOTNOT supersymmetry ---

H.-C. Cheng, Matchev & Schmaltz hep-ph/0205314

Distinctions between the MSSM and MUED’s

Sparticles have different spins from their SM partnerswhile KK particles have the same spin

This would certainly be testable at a LC, but at the LHC maybe not

There is no analog to the heavier MSSM Higgs bosons

The KK partners to the Higgs carry KK-parity, and so should be pair produced (behaving more like Higgsinos than like Higgs bosons)

Smillie & Webber hep-ph/0507171

Barr, hep-ph/0405052limited attempts:

So we see detection of the heavier MSSM Higgs bosons

is crucial for even being sure that we are seeing

SUPERSYMMETRY

Calculation: 01

00 ~2~~ eeji

03

02

~~ Plot: number of e+e- endstates for L=100 fb-1

Only is significant03

02

~~

ee from

* *3 3 4 4

* *3 3 4 4

| Re2cos

| Re2cos

i j i j i jW

i i i i i iW

gZ N N N N

gZ N N N N

Calculation

:

Signficant decays to heavier neutralinos

01

0000 ~2~~, eeAH ji

ee from00 , AH

SUSY BG Calculation:0

10 ~2~~,~~ eejiji

ee eefrom from22

~~ 0~~ji

Monte Carlo• Herwig v6.5

– Inputs from ISASUSY (ISAWIG, HDECAY)– CTEQ6 PDF ( )

• Simulate typical (eg. CMS) detector environment• Private Codes

– Select e+e-+- events• • • each lepton must be isolated

– no charged tracks with within a cone of radius 0.3 rad of each lepton

– energy deposited in electromagnetic calorimeter is less than 3 GeV for 0.05 < r < 0.3

JET VETO eliminates squarks/gluinos

20 < MISSING E_T <130 GeV SUSY BG

GeVpeT 8,10,

4.2, e

GeVpT 5.1SM BG

ExceptZZ*

0~~~~jiji

tHll ~~

GeVmGeVm bt 25.4,175

Double-Wedge: straightforward

Slepton splitting: 2,12,12~

2~

2~

2~

~~,~~

,1101

0

0

elm

m

m

mm

l

l

i

i

01

04

~~

01

03

~~

01

02

~~

Understand Contributions to the Double-Wedge

• Higgs Component

• Chargino Component

01

~, 2

mm AH

0~~ji

03

02

~~

003

02

~~~~ji

Agenda

Use LHC to measure MSSM Parameters as accurately as possible– If Low Energy SUSY is correct, the gluino and

squarks will be seen– Sleptons, neutralinos

lmM ~2,1 ,tan,,

Tji Eee

anythingpp

00 ~~

i,j=2,3,4

Base MSSM Parameters

• Heavy Colored Sparticles

• Optimal Higgs

• Light Selectrons/Smuons

• Other– R-parity, No Flavor Mixing

GeVm

GeVm

RL

RL

l

l

250

150

,3

,2,1

~

~

GeVmA 600

GeVm

GeVm

q

g

1000

800

~

~

22

1 tan3

5MM W

10tan RELAX THESE PARAMETERS LATER

Discovery region (for signals)

x 7

Different Wedge-box structure in

diffenent districts

e e

1. Neutralino PP

2. Direct channel

4.Tau signatures

3. I WB plot

Spoiler mode 0 02 1( )or

02

M M 0

2 lM M

1. Neutralino PP

2. Direct channel

4.Tau signatures

3. I WB plot

Selection rules

• 1.Choose smaller sum of the invariant masses of two pairs.

• 2. Choose smaller opening angle between (or ).

• Efficiency to choose the “correct” pairs ~ 80%

Powerful enough to reconstruct the wedge-box structure.

e e

1. Neutralino PP

2. Direct channel

4.Tau signatures

3. I WB plot

Simulation result

2

:

tan 10

210( )

280( )

2000( )

3000( )

150( )

250( )

2500( )

A

q

l

g

MSSM parameters

GeV

M GeV

M GeV

M GeV

M GeV

M GeV

M GeV

1. Neutralino PP

2. Direct channel

4.Tau signatures

3. I WB plot

Improved wedge-box plot method

• With this method, we can get :

3. investigation of signals

1. more explicit wedge-box structure

2. enlarged discovery region

1. Neutralino PP

2. Direct channel

4.Tau signatures

3. I WB plot

• coupling is suppressed

• Same reason kills

plus more phase space supression.

dominance in direct channel0 02 3

0 03 3

2 20 03 4| Re

2cosi i i iW

gZ N N

0 02 2Z

Higgsino components cancel

0 0 * *3 3 4 4| Re

2cosi j i j i jW

gZ N N N N

i j

Cancellation less severe

1. Neutralino PP

2. Direct channel

4.Tau signatures

3. I WB plot

Salient points about (c):

Produces jets, cannot be hadronically quiet

No fundamental vertex0 0i jS

each –ino produced independently

reduction in number of possible patterns

IF -ino pair production is only due to gluinos

possible on Dalitz-like plots

APFB05

Know and rates know rate. 0 0i i 0 0

j j 0 0i j

But squarks can also contribute significantly!!

2ij i jr r r

(or only one kind of colored sparticle)

APFB05

Beenacker et al., NPB 492 (1997) 51

APFB05

EW gaugino unification

endpoints become bands

Sleptons relatively light to enhance leptonic BRs

APFB05

APFB05

hep-ph/0501157

APFB05

simulate signals and backgrounds

realistic calorimeter simulation package (recent CMS package)

with HERWIG 6.5 event generatorcoupled to

Now actually

From Table can determine relative rates for different –ino pairs

Point C: 22 33 44: : 131.5 :1.3 :1r r r

23 24 34: : 10.2 : 9.6 :1r r r

APFB05

CUTS

Note: lose up to 90% of inclusive 4-lepton events mostly due to one or more leptons being too soft.

Simple set of

APFB05

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APFB05

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charginoscharginos!!!

Note: these are inclusive 4-lepton rates with no cuts ore

APFB05

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Now what about non-Higgs boson backgrounds?

Look at processes of the type

1 1 2 2stuffp p X X f f f f

other stuff

Pair production of new heavy states

Decay to SM fermion pairs

Required by some new symmetry of the SM extension

e.g.’s: R-parity in SUSYconservation

ZZ22

-symmetry in little Higgs models FCNC

KK-parity in MUED’s

?X T-parityHubisz & Meade

hep-ph/0411264

the upcoming look beyond the Standard Model (SM)

at the soon-to-commence LHC

Minimal universal extra dimensionsH.-C. Cheng, Matchev & Schmaltz hep-ph/0205314

APFB05

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APFB05

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