Physics Analysis Planning for LHCb. NIKHEF Jamboree, December 21-22 Summary of current CKM...

Physics AnalysisPlanningfor LHCb

NIKHEF Jamboree, December 21-22

Summary of current CKM results…

(2005)

CKM is a coherent picture of CP violation within the SMNew Physics will (most likely) appear as corrections on the CKM framework.

or appear in places we haven’t looked (yet) ;-)

Mission Statement:CKM metrology: determine magnitude and phase of coupling constants of the charged weak interactions

possibly in the presence of NPIdentify (or put limits on) the effects of NP on flavour physics observables


CKM metrology in presence of NPDrop all observables which depend on loop diagrams, as there could be (hopefully!) competing New Physics amplitudes…

i.e. those which includes Vtd (or Vts)

Only these two are left: phase and magnitude of Vub/Vcb

|Vub/Vcb| seems mission impossible for LHCb

If anyone has suggestion on how LHCb could compete here, please let me know!


Arg(ABB)=2+2Bd

Testing for NP in Bd mixing

0 0 0 0

2 d d d

Bd

d d

i SM

B B BB BACA e

SM

0 0

0 0

( ) ( )0.0026 0.0067

( ) ( )sl

B X B XA

B X B X

NP

Disfavored by Asl

d=0 NP phase = SM phase(Minimal Flavour Violation Scenarios)

φBd = -4.7 ± 2.3; [-9.9,1.0] at 95 % C.L.

CBd = 1.27 ± 0.44; [0.56,2.51] at 95 % C.L.

Tree processes : NP free NP should still satisfy these

constraints!


Tree processes : NP free Testing for NP in Bs mixing

SM?I want you to

measure Acp(BsJ/)

I want you to measure ms

Remember B0d oscillations:

Predicted heavy particle… mtop>50 GeV

• Needed to break GIM cancellations

W

W

b

Bs0

s

b

s

B s

0

t

t

Bs–Bs oscillations: “Box” diagram–

msSM |Vts|4

Size of the Box: Bs mixing (Δms)

Phys.Lett.B192:245,1987

New particles can augment the SM Box:

ms |Vts2+ANP|2

?

bs

sb

Bs Mixing Phase : BsJ/ψφ

• Δms is sensitive to |A(BsBs)|

• We can also probe the phase of A(BsBs) Interference of amplitudes

sinφSM = -Aηλ4/Aλ2 = -ηλ2

-0.03 Any larger asymmetry

means new physics…

Ball et al,Phys.Rev.D69(115011),2004hep-ph/0311361

Dunietz et al,Phys.Rev.D63(114015),2001hep-ph/0012219

,

sin arg arg sin

sCP B J

s s s s

A t

A B J A B B J m t

bs

sb

SM non SMiA e

SMiSMA e

BSMiBSMA e

+

Example NP model: SUSY SO(10)

(10)

1 116 16 10 16 16 10

2 2T T

SO f u f Hu f d f HdW Y Y

* *d

Dd CKM d MNS CKM s MNS

b

y

Y V Y U V y U

y

Chang, Masiero, MurayamaPhys.Rev.D67 (075013), 2003, hep-ph/0205111

• YU contains the large top coupling

• YU can be symmetric. In Yu diagonal basis we have:

• Superpotential: (16 are fermions, 10 Higgses)

• Break to SU(5)• Break to MSSM (+rh ν):

* 1

2D D Du L R u u L R u L R d d R L d R RW Y Q U H Y L N H Q D H V Y U E L H MN N * D

dV Y U

Without neutrino mass, UMNS could be rotated away

Neutrino mixingangle

bR

~

Just as in the SM, werotate the d-quarks

Consequences of SO(10) GUT and (drR,db

R,dgR,νL,L) multiplets:

No effect in sR↔bR (i.e. CKM), because there is no right handed coupling

Observable effects in mixing between s̃↔b̃• The Box Diagram (ΔB=2):

– Bs mixing: BsDs-π+

– CP phase: BsJ/ψφ

• Penguins & Rare decay (ΔB=1):– Rare decays: BK*μ+μ-

– B(s)μ+μ-

SUSY SO(10): neutrino mixing squark smixing

Not just SUSY can cause effects…

Rare decays: B(s)μ+μ- &

BK*μ+μ-

• s̃↔b̃ also appears in Penguin Diagram Affects rare decay B0K*μ+μ-

Blazek,Dermisek,RabyPhys.Rev.D65(115004),2002hep-ph/0201081

Dedes,Dreiner,NierstePhys.Rev.Lett.87(251804),2001hep-ph/0108037

The “smoking gun” of SO(10) Yukawa unification...

s sμ- μ-

μ+μ+

μ+

μ-

s̃�

Tevatron: BR <1.5 10-7

SM: BR=3.4 10-9

Similarly, Bsμ+μ- is very promising• SO(10) unifies fermion masses, and predicts: tan β = mt(MZ)/mb(MZ)~ 40-50

Ali et alPhys.Rev.D61(074024),2000,hep-ph/9910221

Babu,KoldaPhys.Rev.Lett.84(228),2000 hep-ph/9909476

b s


Context: Some History


Additional physics within LHCb:

Time-Dependent CP in B0 ‘bc(cs)’ (reference beta)

Time-Dependent CP in B0 ‘bs(ss)’ (beta with penguins)

Time-Dependent CP in B0 ‘bu’ (alpha)Two body

Quasi Two body

Three body

…

Direct CP in Two-Body ‘bu’ decays, both B0 and Bs

Sensitive to gamma (if s↔d symmetry holds)

B0D(*)K(*), B+D(*)K(*) (ADS,GLW, Dalitz, … )Current world’s best constraint…

But maybe it is based on an upward fluctation of r…

Radiative B-decays (bs, bd)Could determine |Vts/Vtd| without measuring ms

Mixing and CP in D-decaysAny non-zero observation would be NP…

…


A Theoreticians (G. Isidori) Shopping List

Four Lines of Attack on “bs”1) Amix(BsDs)Acp(BsDsK)

2) Acp(BsJ/)

3) Br(B(s) )

4) Afb(B0K(*)), Afb(bs)

This list does NOT includeintermediate ‘stepping stones’or (sometimes very interesting) spin-off

These subjects exploit LHCb advantages over

otherexperiments:

a. Bs mesons (1-3)b. large production rate (4)c. all charged final statesd. dedicated triggerse. propertime resolutionf. momentum resolutiong. PID, tagging

And are well matched to ourconstruction and reconstructionactivities:

i. OT constructionii. VELO constructioniii. Track reconstruction

1B b s

2B bs

sb

Organisation

1) Amix(BsDs) Acp(BsDsK)

• 1—2 staf, 1 PostDoc, ~3 OIO

2) Acp(BsJ/)


3) Br(Bs )


4) Afb(B0K(*)), Afb(bs)


1) Open Charm and 2) Charmonium

B+ J/K+ and 2S)K+, 2S)+ and J/+,

J/+-

B+ D0+ and D0a1+ and D0+

D0K+-

a1++-+

B0 J/K*0 and 2S)K*0

K*0 K+-

B0 D*+ + and D*+ a1+ and D*+ +

D*+D0+

Bs J/ and 2S)

K+K-

Bs Ds+,and Ds a1+ and Ds+,

Ds+,and K*0K- and K+K-+ and

Bc Bs(J/) and DsJ/ and J/

Timeline 1 & 21

8

2

Acp(J/)

9

PID

6

43

5

A0,A//,A┴

triple product

B-production@LHC

ms

7

Tagging

Tim

e

Lifetime ratios,

1) Select exclusive B J/X

2) Select exclusive B D(s)(*), D(s)(*)

3) Determine propertime resolution with exclusive J/X

4) Determine propertime resolution & trigger efficiency vs. propertime for/with D(s)

(*)D(s)(*)5) Angular analysis B0J/ K*

and Bs J/6) Measure lifetime ratios with

exclusive J/X7) Determine tagging

performance, measure/limit ms

8) Bs J/ tagged time-dependent transversity & CP

9) BsDs(K/) tagged time-dependent CP

3) BK* and 4) B(s)

J/ K* and (2S)K* are both background & calibration sample for K*J/ gives normalization for Br(B(s))

Both channels need excellent vertex (VELO) and momentum resolution (OT)to select signal and reject background (due to lack of intermediate resonances)

2

3

4

5

1) Select inclusive J/2) Select exclusive B J/X3) Determine propertime

resolution with exclusive J/X

4) Angular analysis B0J/ K* and Bs J/

5) Selection of K*6) Selection of B(s)7) Determination Afb(K*)

7

6

1

• We have defined a physics analysis roadmap

• Focus on bs transition in a way which profits from LHCb strong points

• And which covers both ‘CKM metrology’ and ‘Physics Beyond SM’ discovery

• Roadmap matches our (re)construction efforts

• Large part of our plan is well established within the LHCb collaboration

– See eg. Reoptimization TDR

• And is embedded within LHCb collaboration– GR convener ‘propertime & mixing’ physics group & member ‘Physics Planning Group’

Summary & Conclusions

routemap

Routemap

BACKUP

Strengths of indirect approach• Can in principle access higher scales and therefore see effect earlier:

– Third quark family inferred by Kobayashi and Maskawa (1973) to explain small CP violation measured in kaon mixing (1964), but only directly observed in 1977 (b) and1995 (t)

– Neutral currents (+N +N) discovered in 1973, but real Z discovered in 1983

• Can in principle also access the phases of the new couplings:– NP at TeV scale needs to have a “flavour structure” to provide the

suppression mechanism for already observed FCNC processes once NP is discovered, it is important to measure this structure, including new phases

Complementarity with the “direct” approach: – If NP found in direct searches at LHC, B (as well as D, K) physics

measurements will help understanding its nature and flavour structure this workshop to explore such

complementarity

VELO

TT

T1 T2 T3RICH2

RICH1

Magnet

PYTHIA+GEANT full simulation

Expected LHCb tracking performance

10 mm

MC truth

100 m

High multiplicity environment:— In a bb event, ~30 charged

particles traverse the whole spectrometer

MC truthReconstructed

Full pattern recognition implemented:— Track finding efficiency > 95%

for long tracks from B decays(only 4% ghosts for pT > 0.5 GeV/c)

— KS+– reconstruction 75% efficient for decay in the VELO, lower otherwise

Expected tracking performance

• Proper time resolution:ATLAS: t ~ 100 fs

(was 70 fs)CMS: t ~ 100 fsLHCb: t ~ 40 fs

BsDs proper time resolution

t ~ 40 fs

• Mass resolutionsin MeV/c2

ATLAS

CMS

LHCb

Bs 80 46 18

Bs Ds 46 – 14

Bs J/ 38 32 16

Bs J/ 17 13 8

Good proper time resolution essential for time-dependent Bs measurements !

without J/ mass constraint

with J/ mass constraint

— S/B ~ 3 (derived from 107 fully simulated inclusive bb events)

Bs oscillations Measurement of ms is one of the first LHCb physics goals

—Expect 80k Bs Ds+ events per year (2 fb–1), average t ~ 40 fs

Distribution of unmixed sample after 1 year (2 fb–1) assuming ms = 20 ps-1

5 observation of Bs oscillationsfor ms < 68 ps–

1 with 2 fb–1

LHCb

Bs oscillations

Current SM expectation of ms (UTFit collab.):

LHC reach for 5 observation:

ATLAS/CMS 30 fb–1 3 years̃

LHCb 0.25 fb–1 1/8 year

s and s from BsJ/, …• Bs J/ is the Bs counterpart of B0J/ KS:

– Bs mixing phase s is very small in SM: s = –arg(Vts2)=–22 ~ –0.04

sensitive probe for new physics

– J/ final state contains two vectors:• Angular analysis needed to separate CP-even and CP-odd• Fit for sin s, s and CP-odd fraction (needs external ms)

• Sensitivity (at ms = 20 ps–1):

– LHCb: • 125k Bs J/ signal events/year (before tagging), S/Bbb > 3

stat(sin s) ~ 0.031, stat(s/s) ~ 0.011 (1 year, 2 fb–1)

• can also add pure CP modes such as J/, J/’, c (small improvement) stat(sin s) ~ 0.013 (first 5 years) will eventually cover

down to ~SM

– ATLAS:• similar signal rate as LHCb, but stat(sin s) ~ 0.14 (1 year, 10 fb–1)

– CMS:• > 50k events/year, sensitivity study in progress

Exclusive b s

s = (m)2 [GeV2]

AFB(s̃) for B0K*0

s = (m/mb)2^

AFB(s̃) for b+– ^

MSSM C7eff>0

ATLAS expectation for 30 fb–1

SM

LHCb:— 4400 B0 K*0 events/2fb–1, S/B > 0.4— After 5 years:

zero of AFB(s) located to ±0.53 GeV2 determine C7

eff/C9eff with 13% error (SM)

ATLAS:— 1000 B0 K*0 events/10fb–1, S/B > 1

Other exclusive bs feasible (Bs, b)

Suppressed decays, SM BR ~ 10–6

Forward-backward asymmetry AFB(s) in the rest-frame is sensitive probe of New Physics:

—Zero can be predicted at LO with no hadronic uncertainties, depends on Wilson coefficients

Bs +–

Very rare decay, sensitive to new physics:— BR ~ 3.5 10–9 in SM, can be strongly enhanced in SUSY— Current limit from Tevatron (CDF+D0): 1.5 10–7 at 95% CL

LHC should have prospect for significant measurement, but difficult to get reliable estimate of expected background:— LHCb: Full simulation: 10M inclusive bb events + 10M b, b events (all

rejected)

— ATLAS: 80k bb events with generator cuts, efficiency assuming cut factorization

— CMS: 10k b, b events with generator cuts, trigger simulated at generator level, efficiency assuming cut factorization

— New assessment of ATLAS/CMS reach at 1034 cm–2s–1 in progress

1 yearBs + –

signal (SM)b, bbackground

Inclusive bb background

All backgrounds

LHCb 2 fb–1 17 < 100 < 7500

ATLAS 10 fb–1 7 < 20

CMS (1999) 10 fb–1 7 < 1

Physics Analysis Planning for LHCb. NIKHEF Jamboree, December 21-22 Summary of current CKM...

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Transcript of Physics Analysis Planning for LHCb. NIKHEF Jamboree, December 21-22 Summary of current CKM...