flip tanedo, no champs at dØ 1 /19 - cornell university › ~pt267 › files › talks › ... ·...

/19Flip Tanedo, No CHAMPS at DØ 1

CornellUniversity

/19Flip Tanedo, No CHAMPS at DØ

No CHAMPs at DØ

Flip Tanedo

2

7 December 2009Physics 7661, Fall 2009

Collider Physics

Presenting: 0809.4472


WTF is a CHAMP

3

Kobe Bryant4x NBA CHAMPion2009 NBA Finals MVP2008 NBA MVP11x NBA All-Star2x scoring CHAMPion1997 Slam Dunk CHAMPion

Game-winning buzzer-beating 3-point shot last Friday against the Miami Heat. LAL 108, MIA 107.


WTF is a CHAMP

• Long-Lived Charged Massive Particle

• Massive Metastable Charged Particle

• Heavy Stable Charged Particle

• Charged Massive Stable Particles

4

Experimentalist definition

Summary: charged shit that makes it out of the collider before decaying


WTF is a CHAMP

• Approximately conserved quantum numbere.g. electron, proton

• Suppressed effective couplinge.g. muon (e.g. !"e#... man, I hate that process)

• Suppressed phase spacee.g. neutron (I know: not charged, STFU)

5

Standard Model examples


WTF is a CHAMP

• GMSB: gravitino LSP, so NLSP may be chargede.g. third-generation sfermion (stau)

• AMSB: with M2 « M1 « M3, small splitting between $+ and $0

• Focus point CMSSM: M1,2 » !, degenerate Higgsino LSP and Higgsino-lke NLSP

• Split-SUSY: very large squark massmetastable gluino

6

Theorist’s definition


WTF is a CHAMP

• Only consider electric charge

• Colored charges are a different story (R-hadron)

• Also assume CHAMPs are pair producedi.e. ignore cascade decays (for simplicity)

7

Collider definition

Let’s make some simplifying assumptions

Pair production: LEP gives a model-independent-ish M > 100 GeV bound from Z "(CHAMP)2


WTF is a CHAMP

• Muon chamber hit with associated ECAL tracks

1. Large invariant mass (& high pT)

2. Slow velocity (time of flight measurement)

8

Collider definition

Time of flight? We can measure that?

Signature looks just like a heavy muon


The Muon System

9

Fig. 44. Exploded view of the muon wire chambers.

Source: D0 Run II TDR, Nucl.Instrum.Meth.A565:463-537,2006; arXiv:physics/0507191

Different times of flight for particles at different polar angles are compensated for by varying cable lengths since the front-end electronics do not allow such timing adjustments.


Cuts and BG• 2 “muons” with pT > 20 GeV

• At least one track is ‘collimated’ (ET, pT)Reducible BG: mesons

• Acolinear, outward moving muonsReducible BG: cosmic rays (very bad!)

• Sufficiently close to the beamlineReducible BG: Bs, beam halo, cosmic rays

• Irreducible BG: mismeasurements

10


Background Simulation

• Randomly combine separate distributions of invariant mass and velocityCentral tracker is independent of muon chamber

• Velocity BG: ‘events’ invariant mass in Z peak: 70 - 110 GeV, passes other cutsThis is why the pair production assumption is useful

• Invariant mass BG: negative velocity events

• Subtle: modeling BG from the data itself. Chosing randomly from separate data sets gives us decorrelated background simulation.

11


Data vs. Monte Carlo

12

(1! v)/!v


Stau Mass [GeV]50 100 150 200 250

) [p

b]

- 1!"+ 1!"

# p

(p

$

-510

-410

-310

-210

-110

1

10

Observed Cross Section LimitExpected Cross Section Limit

NLO Cross Section PredictionNLO Cross Section Uncertainty

(a) -1DØ 1.1 fb

Charged Gaugino Mass [GeV]50 100 150 200 250 300

) [p

b]

- 1%

+ 1%

# p

(p

$

-310

-210

-110

1

10Observed Cross Section LimitExpected Cross Section Limit


(b)-1DØ 1.1 fb

Charged Higgsino Mass [GeV]50 100 150 200 250 300

) [p

b]

- 1!

+ 1!

" p

(p

#

-310

-210

-110

1

10



(c) -1DØ 1.1 fb

M(GeV)60100200300

Signal4.70.70.10.004

BG30.9 ± 3.9

1.6 ± 0.8

1.7 ± 1.0

1.9 ± 0.7

Obs38113

e.g. Stau CHAMP


Stau Mass [GeV]50 100 150 200 250

) [p

b]

- 1!"+ 1!"

# p

(p

$

-510

-410

-310

-210

-110

1

10



(a) -1DØ 1.1 fb


) [p

b]

- 1%

+ 1%

# p

(p

$

-310

-210

-110

1



(b)-1DØ 1.1 fb


) [p

b]

- 1!

+ 1!

" p

(p

#

-310

-210

-110

1

10



(c) -1DØ 1.1 fb

M(GeV)60100200300

Signal4.70.70.10.004

BG30.9 ± 3.9

1.6 ± 0.8

1.7 ± 1.0

1.9 ± 0.7

Obs38113

e.g. Stau CHAMP

Above the blue line is excluded

Red line is the prediction for some arbitrary CHAMP model

This intersection is the lower bound on the CHAMP mass


Stau Mass [GeV]50 100 150 200 250

) [p

b]

- 1!"+ 1!"

# p

(p

$

-510

-410

-310

-210

-110

1

10



(a) -1DØ 1.1 fb


) [p

b]

- 1%

+ 1%

# p

(p

$

-310

-210

-110

1



(b)-1DØ 1.1 fb


) [p

b]

- 1!

+ 1!

" p

(p

#

-310

-210

-110

1

10



(c) -1DØ 1.1 fb

M(GeV)60100200300

Signal4.70.70.10.004

BG30.9 ± 3.9

1.6 ± 0.8

1.7 ± 1.0

1.9 ± 0.7

Obs38113

e.g. Stau CHAMP

M(GeV)60100200300

Signal4456550.2

BG23.6 ± 3.3

1.6 ± 0.8

1.9 ± 0.5

1.7 ± 0.6

Obs24112

e.g. Gaugino CHAMP

Above the blue line is excluded

Red line is the prediction for some arbitrary CHAMP model

This intersection is the lower bound on the CHAMP mass


LHC?

14

Raklev, 0908.0315

In some regions, LHCb might be able to do better due to particle ID. E.g. medium-lived particles that decay inside the detector.

extr

a sli

de


Bethe-Bloch

• Energy loss is almost independent of CHAMP mass

• So we can use the tracking system and treat CHAMP as !

• p measurement in central tracker +% measurement from ! system = m measurement

• But: software assumes %=1, track fit is poor for %<0.75Can treat % as an additional fit parameter, good to %>0.5

15

Raklev, 0908.0315

Signatures depend on interaction with detector

!"dE

dx# =

Kz2Z

A!2

!1

2ln

2mec2!2"2Tmax

I 2" !2 " #

2

"CHAMP charge Max possible KE transfer

CHAMP velocity

depends on %

extr

a sli

de


Other CHAMPs

• UED with KK-parity

• RS with GUT-parity

• DSB (quantum numbers)

• Leptoquarks

• Additional generations

• Magnetic Monopoles

16

extr

a sli

de


CHAMP Cosmology

• Hard to get a viable dark matter CHAMP

• Strong constraints from, e.g, BBN, CMB, ...CHAMP decay injects energetic particles into the plasma, abundance of light elements

• A CHAMP @ LHC would require model building to dilute its early universe density

17

extr

a sli

de


Other Ideas

• Slepton trapping in water tanks Feng hep-ph/0405278 (colliders)Byrne hep-ph/020252 (cosmic rays)

• R-hadrons: CHAMPs + quarksInteractions with nuclei mainly due to quark. Can swap quarks, change electric charge.

18

extr

a sli

de


Happy Winter Break!

19

• DØ, 0809.4472• CDF note 8701• Fairbairn et al,

hep-ph/0611040• Raklev, 0908.0315• Feng & Smith,

hep-ph/0409278

References

flip tanedo, no champs at dØ 1 /19 - cornell university › ~pt267 › files › talks › ... ·...

Documents