The Physics reach
of a Super B factory
STEVE PLAYFER
UNIVERSITY OF EDINBURGH
LHCb Upgrade Workshop, Edinburgh
January 11/12th 2007
Integrated
Luminosities
J.Libby, April 2006 10/fb vs 50/ab
LHCb
Most projections
are for 2/fb or 10/fb
Upgrade -> 30/fb?
5x1012 b quark pairs
Super B factories
Most projections
are for 10/ab or 50/ab
Could collect 100/ab
1011 b quark pairs
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Luminosity and Backgrounds
SuperKEKB
Beam currents 5-10A
Crab cavities rotate
bunches for collisions
Luminosity L=4-8x1035
Backgrounds x10-20
ILC-based SuperB
Beam currents 2-4A
Very small final focus
with travelling crab waist
Luminosity L=1-2x1036
Backgrounds x1-2
ILC-based SuperB is more ambitious than
SuperKEKB!
Projections depend on backgrounds, as well as
integrated luminosity
Projected errors at SuperKEKB
50/ab
syst. error
Theory err.
0.004
0.014
~0.01
α
1.2º
a few º
γ
1.2º
O(1) º
1%
~1%
S(φKs)
0.023
0.020
A(φKs)
0.016
0.018
S(η’Ks)
0.013
0.020
A(η’Ks)
DCPV in b→sγ
0.009
0.017
0.003
0.002
Obs.
Sin2β
|Vub|
stat. error
~5 %
0.003
“Most interesting measurements are
systematics limited after 50/ab” - Yamauchi
Observable
CKM2008-10 (2ab-1)
SuperB (50ab-1)
Comments
sin(2β) (b→ccs)
<1 °
<1°
no improvement
Globally
could be
a factor 5
improvement
sin(2β) (Peng.)
φK
(f0,η’π0)K0
3K
~4°
~(6,3,5)°
~3°
<2°
~(2,1,2)°
~1°
α (ππ,ρρ,ρπ)
5° -8°
~1°
γ (DK)
(5-10)°
(1-2)°
(Tree decays)GLW+ADS+Dalitz
also precisely measured at LHCb
Vcb-incl
Vcb-excl
1%-1.5%
4%
0.5?
1%?
More theo. parameters from data
Depends on Lattice
B →D*τν
10-15%
2-3%
SM -senstitive to NP (H±)
Vub-incl
Vub-excl
10%
10%
2%?
2%?
More theo. parameters from data
Depends on Lattice
Br(B → lν)
Br(BÆ μ υ)
20%
visible
4%
8%
>5 improvement
Lattice is crucial
Br(B → (ρ,ω),γ)
0.1 × 10-6
0.03 x 10-6
|Vtd/Vts| from ργ/K*γ dep. Lattice
Br(B → μμ)
Br(BÆeμ)
90%CL @ 1×10-8
90%CL @ 2×10-8
not measurable
Interesting for MFV – at 2ab-1 off by two order of
magnitude..
AFB (Xsl+l-) -s0
AFB (K*l+l-) –s0
ACP (K*l+l-)
at high masses
25%
25%
6%
12%
5%
9%
[1-1.5]%
2.5%
for exclusive modes (and mainly for muons)
also precisely measured at LHCb
ACP (Xsγ)
ACP (K*γ)
[1-2]%
0.65%
[0.5-1]%
~0.3%
Interesting if σ<0.5% (SM)
Exclusive modes precisely measured @ LHCb
50/ab at SuperB - Achille Stocchi (CKM 2006)
Sin 2β from Charmonium
Main Systematics:
Vertex resolution
Tagging
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
B0 flavour sample
used to study the
systematic errors
Sin2β = 0.710+-0.034(stat)+-0.019(syst)
|λ|= 0.932+-0.026(stat)+-0.017(syst)
With 2/ab syst. and
stat. errors are
already equal
ASL measurement with dileptons
ASL = [N(l+l+) - N(l-l-)]
/
[N(l+l+) + N(l-l-)]
SM: ASL = -0.0005+-0.0001
HFAG: ASL = -0.0030+-0.0078 BaBar/Belle electron pairs
Already systematics limited (detector charge asymmetry)
QuickTime and a
TIFF (LZW) decompressor
are needed to see this picture.
D0 muon pairs (2006)
D0 magnets reversed weekly
Dominant systematic from K->μ decays
… is it possible to make a 10-4 measurement?
Sin 2β from Penguins
Theoretical
differences:
+ a few % in
“clean” modes
>10% otherwise
Replace “naïve”
average with
“informed” average
of φKS, η’KS,
KSKSKS
0.52+-0.06
(>2σ from J/ψΚs)
ACP(t) in Bd -> φKS and Bs -> φφ
SuperB: 1K Bd->φKS and φKL events per /ab with S/B>1
accuracy on Δβ ~0.03 in 50/ab
LHCb: 400 Bd->φKS events per /fb with S/B~1
accuracy on Δβ ~0.10 in 10/fb
LHCb: 2K BS->φφ events per /fb with S/B~1
Is Δφs
different
from Δβ?
accuracy on Δφs ~0.03 in 10/fb
Can LHCb compete with B factories in Δβ modes?
Radiative Penguin decays
Inclusive b->sγ
BF~5% limited by theory and systematic errors after 2/ab
New NNLO calculation is below HFAG average - still interesting!?
Direct CP asymmetries statistics limited
Can reach SM prediction ~0.5%
Vtd/Vts from b->dγ
Exclusive B->ργ/K*γ ratio is theory limited after 2/ab
Isospin asymmetry measures γ (annihilation diagram)
Inclusive b->dγ may be possible at SuperB
Photon helicity with ACP(t) in K*0γ ...
Statistics limited even with full luminosities
Angular analysis of B->Kφγ is also interesting
The angle α
Isospin analysis of ππ system
Measure all 3 BFs, 3 direct ACP, ACP(t) in π+π−
New idea to use γ->e+e- for ACP(t) in π0π0
Reduces to 2x ambiguity in determination of α
Isospin analysis of ρρ system
Measure all 3 BFs, 3 direct ACP, ACP(t) in ρ+ρ− and ρ0ρ0
Time dependent Dalitz analysis of ρπ
Analysis is very complicated (27 parameter fit)!
Important to resolve ambiguities in isospin analyses
Need to do all of these to understand α to ~1 º
ρπ is limited by systematics from ρ’ and cross-feed
π0π0 and ρ0ρ0 are limited by statistics
The angle γ
GLW method: B->D0K, D0->CP eigenstate
Interference between b->u/b->c small, rb ~0.1
ADS method: B->D0K, D0->K+π- (DCSD)
Very low statistics in DCSD decay
Dalitz method: B->D0K, D0-> KSππ
Need to understand Dalitz plot distribution
U-spin method: Bs->K+K- and Bd->π+πSuperB would have to run at Y(5S)
SU(3) analysis of Kπ/ππ modes
Theoretical uncertainties under control?
Is γ still statistics limited at SuperB?
γ from B−>DK Dalitz
Interference of b−>cus and
b−>ucs tree diagrams
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
DK: γ = 66+19-20o rb = 0.16
D*K: γ = 86+37-43o rb = 0.18
DK*: γ =
11+23
o
-57
rb = 0.56
γ sensitivity
γ = 53 +15-18 +-9o
DK:
D*K:
γ=
rb
o
92+-41+-16
< 0.14
rb < 0.21
Error depends critically on rb
Sensitivity
rb=0.1
B-tagged analyses
Reconstruct one B as tag for the other
Hadronic tags (0.25% efficient)
Semileptonic tags (0.7% efficient)
Best method for inclusive b -> ulν, sγ
Neutrino modes
B -> τν and Dτν can be measured to a few %
B -> μν and sνν observable with 50/ab
Hermeticity is crucial for Β−> τν
17 signal events
from 450M BB
3.5σ significance
Fit is to extra
energy recoiling
against B tags
BF( B → τ ν τ ) = (1.79
) ×10
f B Vub = 10.1+−11..46 ( stat ) ( syst ) × 10 −4 GeV
+
+
(
+0.56 + 0.39
− 0.49 − 0.46
+1.3
−1.4
−4
)
Vub from B−>πlν
BaBar untagged
analysis
Error bars dominated
by background
subtraction
At SuperB can do a
B tagged analysis
Form factor
measurement is
crucial to constrain
theory errors
Vub = (3.5+-0.4(shape)+-0.1(BF)) x 10-3 P.Ball hep-ph/0612190
Β−>Κ∗ll FB asymmetry
Belle and BaBar already
rule out wrong sign
C9*C10 and C7
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Full angular analysis
and s(AFB=0) possible at
both LHCb and SuperB
a
Q
Advantages of SuperB:
¾ electrons and muons
¾ inclusive and exclusive
Super B
50/ab
Super B running at Y(5S)?
Can’t measure Bs oscillations or ACP(t)
Could measure ΔΓs/Γs, ASL and direct ACP
Could measure rare Bs decays
Sacrifice some Y(4S) luminosity to run at Y(5S)
Test runs by CLEO/Belle
Bs*Bs*
Can separate BS production
Belle sees 3 J/ψφ and
1 φγ event in 2/fb
Bs*Bs
BsBs
Potential of SuperB with
1-10/ab at Y(5S) under study
D0 Mixing
BaBar Kππ0
+K3π
Semileptonic and neutral
decays are also important
SuperB produces 5x109 D
mesons per /ab
D->K+π− 50/ab SuperB
=> 20/fb LHCb (D.Asner)
Lepton flavour violating τ decays
Many different
τ decays can be
studied
(not just the ones
shown here)
SuperB starts to get
into the interesting
region ~10-9
My Final Scorecard
Measurement
Sin2β
φs in Bs mixing
Δβ in penguins
α in ππ, ρπ, ρρ
γ in B->DK
Vub
b->s(d)γ
b->sll, ll
LHCb
** (syst. limited)
***
* (trigger?)
* (some modes)
*** (more methods)
* (maybe πlν?)
* (Bs->φγ)
*** (K*μμ,Bs->μμ )
SuperB
** (syst. limited)
No
*** (many modes)
*** (all modes)
**
** (theory limited?)
*** (incl. & excl.)
*** (stat. limited)
B->τν, μν, sνν
D mixing
LFV τ decays
No
* (only D->Kπ?)
* (only τ−>μμμ?)
** (stat. limited)
***
*** (many modes)
Backup Slides
Status of CKM
Includes Bs
mixing results
from CDF/D0
There are
several
measurements
for each UT
angle and side
“Desperately
consistent
with the
Standard Model”
Bs Mixing Measurement
Agrees with
CKM fit
Vtd/Vts is
already
limited
by theory!
Δms = 17.33+0.42-0.21+-0.07 /ps
Δms = 17.77±0.10(stat)±0.07(syst)
ps-1
Vtd/Vts = 0.2060+-0.0007(exp)+0.0081 (theo)
-0.0061 (theo)
Measuring
to more
accuracy
is not
interesting?
Sin 2α from B−>ρρ & Β−>ρπ
B−>ρρ
ρρ not “lucky” expected!
Almost 100% polarized
B(ρ0ρ0) = (1.1 +- 0.4) x 10-6
Small B(ρ0ρ0) limits
isospin analysis to
ρ+π−
Dalitz analysis of B−>ρπ
ρ0
π0
ρ−π+
S = −0.10 ± 0.14 ± 0.04
C = 0.34 ± 0.11 ± 0.05
α from time-dependent
analysis of interference
regions
α−αeff. < 18o
Vub Exclusive vs Inclusive
LCSR
tagged
LQCD
FF
LQCD
SL tag
untagged
quenched LQCD
Incl |Vub|
(BLNP)
Not sure this is really a problem. Wait for more
data!
Vub from Inclusive b−>ulv
P+=Ex-|px|
253M BB
Hadronic Tags
88 × 106 BB pairs
b → ulν
MC signal
data
Lepton
Endpoint