physics analysis planning for lhcb. nikhef jamboree, december 21-22 summary of current ckm...
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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
NIKHEF Jamboree, December 21-22
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!
NIKHEF Jamboree, December 21-22
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!
NIKHEF Jamboree, December 21-22
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
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
NIKHEF Jamboree, December 21-22
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…
…
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/)
• 1—2 staf, 1 PostDoc, ~3 OIO
3) Br(Bs )
• 1—2 staf, 1 PostDoc, ~2 OIO
4) Afb(B0K(*)), Afb(bs)
• 1—2 staf, 1 PostDoc, ~2 OIO
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
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