staus at the lhc - kekresearch.kek.jp/group/riron/workshop/kekph2007/march2/kekph07_hama.pdf ·...

Staus at the LHC

based on the works KH, M.M.Nojiri, A.de Roeck (hep-ph/0612060); KH, M.M.Nojiri, Y.Kuno, T.Nakaya (’04);W.Buchmüller, KH, M.Ratz, T.Yanagida (’04);

at KEKPH’07, Mar.’07

Koichi Hamaguchi (Tokyo U.)

Staus at the LHC

Long-lived

Staus at the LHC

Long-lived

this week

and in the early universe

+ KH, T.Hatsuda, M.kamimura, Y.Kino, T.T.Yanagida (hep-ph/0702274)W.Buchmüller, KH, M.Ibe, T.T.Yanagida (’06).

OutlineMotivation + Introduction

Long-lived staus @ LHC

Stopper-detector

Study of stau decay

Remark (catalyzed BBN)

Summary

Motivation:

Can we test the Supergravity at the LHC ?

What would prove the Supergravity ?

Gravitino Gravitino Interaction: extremely weak

suppressed by (or )

Gravitino Mass: model dependent

MPm eG!

eV keV MeV GeV TeV

GMSBgMSB̃

AMSB, mMSB

gravity-MSB

LSP: Cold Dark Matter

We assume SUSY scenarios with

Gravitino LSP (Dark Matter)

Dark Matter in SUSYIn SUSY models + conserved R-parity, the Lightest SUSY Particle (= LSP) is stable.

➞ If neutral, Dark Matter candidate.

Dark Matter candidates in SUSY Standard Model

In SUSY Standard Model in supergravity framework,...

squarks :!

"uRi"dRi

sleptons :!

gauginos and higgssinos : ""0i , $"±

i , %ggravitino : %G

neutral and color-singlet

squarks :!

"uRi"dRi

sleptons :!

excluded by direct detection experiments(cf. Falk, Olive, Srednicki,’94)

squarks :!

"uRi"dRi

sleptons :!

Only Neutralino and Gravitino are viable candidates　for the LSP dark matter!

squarks :!

"uRi"dRi

sleptons :!

Only Neutralino and Gravitino are viable candidates　for the LSP dark matter!

squarks :!

"uRi"dRi

sleptons :!

this talk

NLSP (Next-to-Lightest SUSY Particle)In Gravitino LSP scenario, the NLSP is long-lived.

MPm eG

Interaction

Lifetime e.g. for mNLSP ! 200 GeV!NLSP ! O(day) for m eG ! 10 GeV

!NLSP ! O(10 min) for m eG ! 1 GeV!NLSP ! O(10 sec) for m eG ! 0.1 GeV

We assume SUSY scenarios with

Gravitino LSP (Dark Matter)

+ Stau NLSP.

Then, we may have a chance to test the supergravity at future colliders.....!

W.Buchmüller, K.Hamaguchi, M.Ratz, T.Yanagida ’04

Planck scale measurementW.Buchmüller, K.Hamaguchi, M.Ratz, T.Yanagida ’04

Is this “Planck scale measurement” possible

at the LHC ???

eV keV MeV GeV

e.g., for m!̃ = 100 GeV ,

!!̃µs secmsnsps

kmmmmc!!̃

!(!̃ ! G̃! ) "m5

48"m2G̃

Lifetime (decay length) of NLSP stau

eV keV MeV GeV

e.g., for m!̃ = 100 GeV ,

!!̃µs secmsnsps

kmmmmc!!̃

Detector Size

!(!̃ ! G̃! ) "m5

48"m2G̃

eV keV MeV GeV

e.g., for m!̃ = 100 GeV ,

!!̃µs secmsnsps

kmmmmc!!̃

Detector Size No In-flight decay

!(!̃ ! G̃! ) "m5

48"m2G̃

We will see long-lived charged particle (like muon).!̃!̃

We can precisely measure its mass (by time of flight), and furthermore reconstruct masses of heavier SUSY particles.

Fig. from CMS webpage Fig. from ATLAS webpage

Here, we would like to discuss the next step.

➔ We need to stop the staus.

We would like to study the decay of stau (into gravitino).

Long-lived staus @ LHCHow thick the stopping material should be?

Fig. from Hamaguchi, Kuno, Nakaya, Nojiri ’04

!g, !q ! !!±, !!0 ! !"typically

Review of Particle Physics !"

0 2 4 6 8 0

!g, !q ! !!±, !!0 ! !"typically

Review of Particle Physics

for 100 GeV stau

0 2 4 6 8 0

!g, !q ! !!±, !!0 ! !"typically

for 100 GeV stau

0 2 4 6 8 0

!g, !q ! !!±, !!0 ! !"typically

for 100 GeV stau

0 2 4 6 8 0

If thick enough, part of produced staus may be stopped.

Fig. from CMS webpage

Long-lived staus @ LHCActually, the LHC detector themselves can stop part of staus...

We may identify the position of the stopped stau, but....

Actually, the LHC detector themselves can stop part of staus...

it is difficult to identify its decay, which is out-of-time and not originating from beam interaction point.

..... needs New Idea.

We may identify the position of the stopped stau, but....

Place an additional stopper-detector next to the main detector. [ Hamaguchi, Kuno, Nakaya, Nojiri, ’04 ]

Place a water tank as stopper, and then drain the water to a reservoir. [ Feng, Smith, ’04 ]

Use the stau stopped in the surrounding rock. [ De Roeck, Ellis, Gianotti, Moortgat, Olive, Pape’05 ]

Ideas:

Place an additional stopper-detector next to the main detector. [ Hamaguchi, Kuno, Nakaya, Nojiri, ’04 ]

Place a water tank as stopper, and then drain the water to a reservoir. [ Feng, Smith, ’04 ]

Use the stau stopped in the surrounding rock. [ De Roeck, Ellis, Gianotti, Moortgat, Olive, Pape’05 ]

Ideas:

Only this type can identify the timing and position of

the stopping stau precisely.

stopper = detector??

High segmentation is crucial to reduce the background...

High segmentation Low segmentation

stopper = detector??

cf. atm. neutrino CC event < 1 event/kton/year ➔ OK. charged particle at the surface of detector < 1/cm2/sec (?)

==> For SOUDAN II type detector, this corresponds to < 10% dead time of drift tube ➔ OK.

High segmentation is crucial to reduce the background...

ATLAS vs CMS

diameter length weight

ATLAS 22m 44m 7kt

CMS 15m 21m 12.5kt

CMS is smaller ➔ maybe possible to place stopper-detector(s)

-12-10-8-6 -4-2 0 2 46

12-10-8-6-4-20246810

-8-6-4-202468

-12-10-8-6 -4-2 0 2 46

stopper-detector

5g/cm3

(total weight 8kt)

stopper-detectorWe assume two stoppers next to CMS.

Hamaguchi, Nojiri, De Roeck’06

CMS main cavern

Fig. from a document at a webpage of TS/CV/DC section of CERN.

テキスト

26m diameter x 60m long

3.5m15m

CMSstopper-detector

➔ maybe possible to install stopper-detectors.

-6 -4 -2 0 2 4 6

z-positon[m]

10 12x[m]

10.012.0

-6 -4 -2 0 2 4 6

distribution of stopped stau

-12-10-8-6 -4-2 0 2 46

12-10-8-6-4-20246810

-8-6-4-202468

-12-10-8-6 -4-2 0 2 46

GM point! = 40 TeV Hamaguchi, Nojiri, De Roeck, ’06

How many staus are stopped?

table, too

Hamaguchi, Nojiri, De Roeck, ’06

up to O(1000) staus are trapped!

lifetime measurement ➔ SUSY breaking scale

0 1 2 3 4 5 6 7 8 9

tdecay ! tstop [in unit of lifetime]

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

lifetime [arbitrary unit]2!

for N = 100

Hamaguchi, Nojiri, de Roeck ’06

lifetime !!1 ! F 2 ,"

m eGMP = SUSY breaking scale

Note: possible only in a real-time detector

!!/! = 10 ! 15% for Ne! = 100!!/! = 3 ! 4% for Ne! = 1000

Motivation:

Can we test the Supergravity at the LHC ?

Planck scale measurementW.Buchmüller, K.Hamaguchi, M.Ratz, T.Yanagida ’04

Planck scale measurementCrucial to determine the tau energy precisely.

0 20 40 60 80 100 120 140 160

E! [GeV]

10yrs 1 yr

monthday

m!̃ = 100 GeV

m!̃ = 150 GeV

m!̃ = 200 GeV

m!̃ = 250 GeV

m!̃ = 300 GeV

m eG =!

m2e! ! 2me! E! + m2

Figs. from Hamaguchi, Nojiri, De Roeck, ’06(cf. for ILC, see Martyn’06.)

0 20 40 60 80 100 120 140 160

E! [GeV]

10yrs 1 yr

monthday

m!̃ = 100 GeV

m!̃ = 150 GeV

m!̃ = 200 GeV

m!̃ = 250 GeV

m!̃ = 300 GeV

m eG =!

m2e! ! 2me! E! + m2

0 20 40 60 80 100 120

Low Stat.Best Fit

Ejet [GeV]

50 55 60 65 70 75 80 85 90 95 100

E! [GeV]

50 55 60 65 70 75 80 85 90 95 100

E! [GeV]

!Ejet/Ejet = 150%/!

Ejet/GeV

0 20 40 60 80 100 120 140 160

E! [GeV]

10yrs 1 yr

monthday

m!̃ = 100 GeV

m!̃ = 150 GeV

m!̃ = 200 GeV

m!̃ = 250 GeV

m!̃ = 300 GeV

m eG =!

m2e! ! 2me! E! + m2

0 20 40 60 80 100 120

Low Stat.Best Fit

Ejet [GeV]

50 55 60 65 70 75 80 85 90 95 100

E! [GeV]

50 55 60 65 70 75 80 85 90 95 100

E! [GeV]

!Ejet/Ejet = 150%/!

Ejet/GeV

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8mX/m!̃

m!̃ = 150 GeV, N! = 100010 yrsyrmonth

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8mX/m!̃

00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

mG̃/m!̃

1 · 1018

2 · 1018

3 · 1018

4 · 1018

5 · 1018

6 · 1018

00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

mG̃/m!̃

1 · 1018

2 · 1018

3 · 1018

4 · 1018

5 · 1018

6 · 1018

00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

mG̃/m!̃

1 · 1018

2 · 1018

3 · 1018

4 · 1018

5 · 1018

6 · 1018

00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

mG̃/m!̃

1 · 1018

2 · 1018

3 · 1018

4 · 1018

5 · 1018

6 · 1018

00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

mG̃/m!̃

1 · 1018

2 · 1018

3 · 1018

4 · 1018

5 · 1018

6 · 1018

00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

mG̃/m!̃

1 · 1018

2 · 1018

3 · 1018

4 · 1018

5 · 1018

6 · 1018

Possible if

mass reconstruction Mp measurement

Hamaguchi, Nojiri, de Roeck, ’06

m eG > (0.2 ! 0.3)me!

• may be inconsistent with BBN bounds (especially catalyzed BBN).

Remarkm eG > (0.2 ! 0.3)me!

Recently, bound-state effects have been discussed. ( negatively charged stau ↔ positively charged nuclei )

Pospelov ’06; Kohri, Takayama ’06; Kaplinghat, Rajaraman ’06; Cyburt, Ellis, Fields, Olive, Spanos ’06,KH, Hatsuda, Kamimura, Kino, Yanagida ’07

Pospelov ’06

catalyzed BBNstandard BBN

enhanced

KH, Hatsuda, Kamimura, Kino, Yanagida ’07

Solved the Schroedinger eq. for 3-body system (He4, d, X) exactly,using the state-of-the-art coupled-channel technique.

Boundstate

D + (4HeX) ! 6Li + X

Boundstate

D + (4HeX) ! 6Li + Xastrophysical S-factor

Boundstate

D + (4HeX) ! 6Li + Xastrophysical S-factor

3 4 5 6 7 8Log10!tau_X"sec#$

log10!nX%

X Lifetime

X abundance

upper bound

thermal relic

• But if there is an entropy production of O(a few 100) after NLSP decoupling, the bounds can be avoided.

3 4 5 6 7 8Log10!tau_X"sec#$

log10!nX%

Lifetime

abundance

upper bound

thermal relic O(300)

SummaryFor the gravitino LSP, the NLSP becomes long-lived.

To study the decay of a long-lived charged NLSP, a stopper-detector seems necessary.

O(1)kton stopper-detector may be placed next to the CMS detector.

Stau lifetime is measured well.

If , the mass reconstruction (and hence Mp measurement !) may be possible.

Catalyzed BBN is a problem, but may be solved.

m eG > (0.2 ! 0.3)me!

SummaryFor the gravitino LSP, the NLSP becomes long-lived.

To study the decay of a long-lived charged NLSP, a stopper-detector seems necessary.

O(1)kton stopper-detector may be placed next to the CMS detector.

Stau lifetime is measured well.

If , the mass reconstruction (and hence Mp measurement !) may be possible.

Catalyzed BBN is a problem, but may be solved.

m eG > (0.2 ! 0.3)me!

Anyway, if long-lived charged particles are seen at the LHC,............. trap them!!

• Which particle is the NLSP?

• Usually , and therefore, the NLSP is neutralino or slepton.

• Among sleptons, typically a charged slepton, especially the stau is the lightest. (but sneutrino NLSP is also possible.)

• In general, other SUSY particle can also be NLSP.

me! ! meq me!01

< me!±1

• Which particle is the NLSP?

• Usually , and therefore, the NLSP is neutralino or slepton.

• Among sleptons, typically a charged slepton, especially the stau is the lightest. (but sneutrino NLSP is also possible.)

• In general, other SUSY particle can also be NLSP.

me! ! meq me!01

< me!±1

stopper = detector??Hamaguchi, Kuno, Nakaya, Nojiri, ’04

study of 3 body decay

• LSP may be another weakly interacting particle, like axino

• We want to distinguish the decay into the gravitino from the decay into axino by studying the 3-body decay:

3-body decay ... gravitino vs axino

!! ! X!", (X = !G or !a)

cf.Brandenburg, Covi, Hamaguchi, Roszkowski, Steffen, ’05Buchmüller, Hamaguchi, Ratz, Yanagida ’04

3-body decay ... gravitino vs axino

E! X = !G or !a ??

!E!/E! = 100%/!

E!/GeV

Required number of staus to see 3sigma diff.

!E! = me" /8 (cut : E! > 10 GeV)!! = "/3 (cut : ! > "/6)

3-body decay ... gravitino vs axinoWe divide and into bins,E! !

mea, m eG ! me! , ! = numerical parameter (not yet calculated)

Buchmüller, Hamaguchi, Ibe, Yanagida ’06

staus at the lhc - kekresearch.kek.jp/group/riron/workshop/kekph2007/march2/kekph07_hama.pdf ·...

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