1. Vincenzo Vagnoni (for the LHCb Collaboration)
BOLOGNA
LHCb impact on CKM fits
Vincenzo Vagnoni (for the LHCb Collaboration)
Nagoya, Thursday 14th December 2006

2. LHCb startup and baseline luminosity programme
Startup of LHC beam in 2007
Pilot run at 450 GeV per beam with full detector installed
Establish running procedures
Time and space alignment of the detectors, calibrations
2008: LHC ramps up to 7 TeV per beam
Complete commissioning of detector and trigger at 14 TeV
Including calibration of momentum, energy and particle ID
Start of first physics data taking
Baseline LHCb luminosity programme
Integrated luminosity of ~0.5 fb-1 delivered in 2008, ~2 fb-1 in subsequent years
physics results with 2 fb-1 available in 2010, 10 fb-1 available in 2014
Ongoing discussion for an upgrade beyond 2014: Super-LHCb
Note: instantaneous luminosity at the LHCb IP of 2·1032 cm-2 s-1 is almost two orders of magnitude below the LHC challenges*
Thus we expect the LHCb luminosity requirements can be fulfilled very early in the LHC operation
* the B-physics reach of Atlas and CMS will not be considered in this talk

3. * no improvements on Vub- and Vcb-inclusive determinations assumed
Lattice QCD prospects
To exploit precision measurements where hadronic parameters play a role, a substantial improvement should be achieved during the following decade
Now
Pre-LHCb 6 TFlop year
TFlop year
PFlop year
11% 5% 4% 2%
13% 3%
2.5%
1.5%
Vub-excl.* 6%
Vcb-excl.* 1%
Uncertainties in LQCD calculation dominated by systematic errors, overall accuracy does not improve according to simple scaling laws
Disclaimer: estimates on a 10 years scale very difficult... to be taken cum grano salis
6 TFlop year and 10 TFlop year predictions from S. Lattice QCD: Present and Future, Orsay, 2004 and report of the U.S. Lattice QCD Executive Committee Projections to far future from V. SuperB IV Workshop
* no improvements on Vub- and Vcb-inclusive determinations assumed

4. Where will we be at the end of the B-factories and the Tevatron. (i. e
Where will we be at the end of the B-factories and the Tevatron? (i.e. before LHCb data)
(I)
Bd/B+ sector: B-factories
Assume an integrated luminosity of 2 ab-1 at the (4S) provided by BaBar and Belle together, and...
()  6.5°
From Bpp, Brr SU(2) analyses, and B(rp)o time dependent Dalitz
()  6.5°
From BDK, GLW, ADS and Dalitz analyses
Assuming significant reduction of the systematics, in particular improvements in the knowledge of the D decay model, e.g. using CLEO-c data and/or model independent fits on the Dalitz plane
(sin2)  0.017
Bs sector: Tevatron
Assume (2x) 6 fb-1 collected by CDF and D0, and...
(s)  0.2
(s/s)  0.04
(ms)  0.5%
First direct measurement of s from D0 available: s= ± 0.56 ± 0.01 (see talk by B. Casey)

5. Where will we be at the end of the B-factories and the Tevatron. (i. e
Where will we be at the end of the B-factories and the Tevatron? (i.e. before LHCb data)
(II)
Summer 2006
2008*
Nice improvement in 2008, in particular for r
mostly due to better  and LQCD
* Every projection to the future shown in this talk has been obtained by fine-tuning the central values of future measurements around Standard Model expectations, i.e. no New Physics assumed !

6. LHCb impact with first year physics data (int. L=0.5fb-1)
Data taking in 2008 will be crucial to understand detector and trigger performance and assess the LHCb potential
Can use well established measurements from the B-factories and the Tevatron to “calibrate” our CP sensitivity
B-factory sin2 (final sensitivity ~0.017) vs LHCb-2008 J/KS sin2 (~0.04)
Will demonstrate with already considerable precision that we can keep under control the main ingredients of CP-analyses, e.g. opposite side tagging
Tevatron ms (final sensitivity ~0.09 ps-1) vs LHCb-2008 (~0.014 ps-1, stat. only)
Hadronic trigger, control of proper time resolution, same side K tagging, etc.

7. LHCb impact with first year physics data (int. L=0.5fb-1)
(II)
Perform the first high precision measurement of s
Tevatron s (final sensitivity ~0.2) vs LHCb-2008 (~0.04)
Could make a 5 discovery of New Physics effects in the Bs mixing phase with the first year of data if NP s is O(10°)
Bring down the limit of BR(Bsmm)
Other big milestone in the search for New Physics (see talk by J. Dickens)
Potential to exclude BR between 10-8 and SM value with the first year only !
Other relevant measurements
e.g. b-hadron lifetimes, Bh+h-’ (see J. Nardulli), ...
First results with “more difficult” measurements... get a taste of!
e.g. Dalitz analyses of BDK and B(rp)o

8. sin2 from BdJ/KS
The golden mode at B-factories, already well known, but still relevant to improve the measurement
In one LHCb year (L=2fb-1)
Yield: ~216k BdJ/(mm)KS events with B/S0.8
Sensitivity: s(sin2b) = 0.02
s(sin2b)
now
pre-LHCb
with LHCb at L=2fb-1
with LHCb at L=10fb-1
year
background subtracted CP asymmetry with L=2fb-1
Overall improvement by roughly a factor 2 with LHCb at L=10 fb-1

9. s and s at LHCb Bs J/ is the el-dorado mode at LHCb
counterpart of BdJ/KS for measuring the Bs mixing phase, but also other modes contribute
Signal yield: 130k events per L=2fb-1 with a B/S0.1
very sensitive probe of New Physics effects in the Bs mixing
s = s(SM) + s(NP)
s(SM)=-2l2h, small and very well known from indirect UT fits: ±0.002
slight complication: 2 CP-even and 1 CP-odd amplitudes, angular analysis is needed to separate the states
Sensitivity
with L=2 fb-1
Channels under study s
0.021
BsJ/, Bsc, BsJ/, BsDsDs
Γs/Γs
0.0092
BsJ/
now
pre-LHCb
LHCb at L=2fb-1
LHCb at L=10fb-1
year
s(s)
s poorly known now, but will be known as well as sin2b thanks to LHCb
See J. van Hunen’s talk

10. Sensitivity to 
 more challenging for LHCb, due to the need of reconstructing o’s in hadronic environment
2 analyses under study
Time-dependent Bd(rp)o Dalitz plot 
with L=2 fb-1 LHCb estimates a sensitivity σ10°
Brr SU(2) analysis
Very preliminary studies indicate the need of a few years of LHCb running to improve the current Bdr+r- measurement.
With 2 fb-1 the main LHCb contribution will be most likely the improved measurement of Bd roro (fully charged final state)
Need more time and refined studies to give firm results for 
In the following we will conservatively assume to measure alpha with the Bd(rp)o mode only
r+p-
r0p0
N3π = 14k events / 2 fb-1, B/S~1
r-p+
s() [o]
now
pre-LHCb
with LHCb at L=2fb-1
with LHCb at L=10fb-1
LHCb Bd(rp)o only
year

11. By 2014 sensitivity at about 2 degrees
Sensitivity to  m+ m-
LHCb simulation
r(770)
K* and DCS K*
Several modes to measure  at LHCb
ADS+GLW
Dalitz analysis with D3-body
“Dalitz” analysis with D4-body
Golden BsDsK mode
Sensitivity estimated at ~4.2° with L=2fb-1
Assuming the same improvements of the Dalitz syst. error as for the projections of the B-factories to 2008
s(g) [o]
now
pre-LHCb
with LHCb at L=2fb-1
with LHCb at L=10fb-1
year
B mode
D mode
B+→DK+
Kp + KK/pp + K3p
B+→D*K+ Kp
Kspp
KKpp
Kppp
B0→DK*0
Kp + KK + pp
Bs→DsK
KKp
By 2014 sensitivity at about 2 degrees
See M. Patel’s talk

12. Unitarity Triangle prospects from LHCb only
2010
2014
LHCb L=2 fb-1
LHCb L=10 fb-1
Using , ,  and Dms from LHCb only
+ theory for Dmd/Dms
Not employing the full LHCb potential for  in this study
Somewhat conservative: just  from (rp)o

13. Unitarity Triangle in 2014
Without LHCb
With LHCb at L=10fb-1

14. Allowing for New Physics in the mixing
The mixing processes being characterized by a single amplitude, they can be parametrized in a general way by means of two parameters
HSMeff includes only SM box diagrams while Hfulleff includes New Physics contributions as well
Summer 2006
(r, h) with NP allowed
Four “independent” observables
CBd, Bd, CBs, Bs
CBq=1, Bq=0 in SM
For the neutral kaon mixing case, it is convenient to introduce only one parameter
Using Tree-level processes
assumed to be NP-free
*the effect in the D0-D0 mixing
is neglected
5 additional parameters

15. The r-h plane in 2014 allowing for NP in the mixing
Without LHCb
With LHCb at L=10 fb-1
By allowing for arbitrary NP contributions in the mixing, the UT apex will be basically determined by the Tree-level constraints, and it will be the reference for any NP model building
caveat: neglecting here NP effects in neutral D-meson mixing
LHCb will further constrain the apex, due to substantial improvement in the  measurement

16. Measuring New Physics in the Bs mixing
End of Tevatron
Dramatic impact of LHCb on the Bs mixing phase
can bring down the sensitivity to the NP contribution Bs from 5.6° at the end of the Tevatron to 0.3°
NP in the Bs mixing will be known three times better than in the Bd by 2014
without the need of improvements from theory
With LHCb at L=10 fb-1 in 2014
As far as CBd and CBs are concerned, they are dominated by theory  no great impact from LHCb measurements (CBs)~0.06 (CBd)~0.09

17. Interpretation of s vs sin2
Most precise measurements today available are Dmd/Dms, sin2b and |Vub/Vcb|
A disagreement between Dmd/Dms and g would spot out NP in the magnitude of the mixing amplitudes
But uncertainty on  still too large
To find evidence of NP effects in the Bd mixing phase, it is instead important to compare sin2b with |Vub/Vcb|
but need to heavily rely on Lattice QCD, interpretation in case of slight disagreement not trivial
Example: current UT fits show slight disagreement between sin2b and |Vub/Vcb|, due to excess of Vub-inclusive / defect of sin2b (JHEP 0610 (2006) 081)
First NP hint or theory problem in Vub?
No such interpretation problems for s, just go and measure it ! If different from ±0.002, NP is there

18. Conclusions LHCb will improve the knowledge of the Unitarity Triangle
in particular due to increased precision on the measurement of  and , and maybe to a lesser extent of 
both in Standard Model and (even more) in NP allowed scenarios
LHCb will measure the Bs mixing phase with ultimate precision
Impressive improvement of a factor 20 since the end of Tevatron data taking
NP angle Bs will be known at 5.6° from the Tevatron, and 0.3° at LHCb (with int. L=10fb-1) !
Much easier intepretation than sin2b, NP might show up very early just with the first year of data in 2008
After “LHCb phase I”, in 2014, NP in the Bs mixing will be more constrained than in the Bd
Other big milestones from LHCb, not impacting on CKM fits or not considered in this talk
Radiative and rare decays
BdK*g, Bsfg, BdK*mm, Bsmm
bsss penguins
e.g. Bsff
Bhh’
Charm physics, ...

19. Backup

20. The LHC beauty experiment
Forward-backward correlation of bb angular distribution - b
Single-arm forward spectrometer, acceptance: mrad b
Tracking: Vertex Locator, TT, T1, T2, T3
PID: 2 RICH detectors, SPD/PS, ECAL, HCAL, Muon stations b b
Interaction point
Pythia
100μb
230μb
η of B-hadron
PT of B-hadron
~1 cm B
pp at 14 TeV “b-factory”
Luminosity at IP8 = 2·1032 cm-2s-1
1012 bb produced per year
including all b-hadrons species

21. LHCb Calorimeter
4 devices: Scintillator Pad Detector (SPD), Preshower (PRS), Electromagnetic Calorimeter (ECAL) and Hadronic Calorimeter (HCAL).
Provides with acceptance 30 mrad to 300 (250) mrad:
Level-0 trigger information (high transverse momentum hadrons, electrons, photons and p0, and multiplicity)
Kinematic measurements for g and p0 with sE/E =
Particle ID information for e, g, and p0.
10%
 1% E

22. p0 reconstruction at LHCb
Resolved p0: reconstructed from 2 isolated photons
sm = 10 MeV/c2
Merged p0: pair of photons from high energy pion which forms a single ECAL cluster, where the 2 showers are merged.
The pair is reconstructed with a specific algorithm based on the expected shower shape.
sm = 15 MeV/c2
Reconstruction efficiency: ep0 = 53 % for B0p+p-p0
Resolved π0
Merged π0
Merged
Resolved
Transverse energy (GeV) e
π0 mass (Mev/c²)

23. Tree level determination of  from B±D(*)0K(*)±u B- c s K-
Vcb W l
Interference if same D0 and D0 final states
Favoured
GLW (Gronau,London,Wyler)
Uses CP eigenstates of D0 decays D0
ADS (Atwood, Dunietz, Soni) b u B- K- c s W
D 0
Vub = |Vub | e-ig
Colour suppressed
Dalitz Method – GGSZ analyze D0 three-body decays on the Dalitz plane
strong amplitude (the same for
Vub and Vcb mediated transitions
Break-through of B-factories, but statistically limited and extremely challenging!
strong phase difference between
Vub and Vcb mediated transitions
rB is a crucial parameter - the sensitivity on  depends on it

24. Bounds on NP size and phaseBd Bs
dark: 68%
light: 95%
dark: 68%
light: 95%
The allowed NP amplitude is still large for small phase shift
MFV scenarios are strongly favored at this point, but we still
might see a large NP phase in Bs mixing

25. the CKM picture, but rather as a «correction»
MFV or not MFV?
New Physics in the bd and recently in bs sector starts to be quite constrained and most probably will not come as an alternative to
the CKM picture, but rather as a «correction»
Minimal Flavour Violation:
the only source of flavour violation is in the SM Yukawa couplings (implies =0)
New Physics couplings between third and second families (bs sector) stronger with respect to the bd ones
Flavour physics needs to improve existing measurements in the Bd sector and perform precise measurement in the Bs sector (mixing phase still largely unknown)

26. LHCb sensitivity: summary
2010 L=2 fb-1
2014 L=10 fb-1 
4.2°
2.4°
sin2
0.02
0.009
 from ()° only
10° 7° s
0.021
s/s
0.004

27. Pre-LHCb: B-factories and Tevatron at end of their life, 2008-2009
Perspectives up to 2014
Pre-LHCb
2010
2014 
6.5°
3.5°
2.3°
sin2
0.017
0.013
0.008 
5.4°
4.8° s
0.2
0.021
0.009
s/s
0.04
0.004
Pre-LHCb: B-factories and Tevatron at end of their life,