The BaBar experiment - Istituto Nazionale di Fisica Nucleare · PDF fileThe BaBar experiment...
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The BaBar experiment
Flavor Physics at the B Factories
Present status
Future perspectives
L.Lanceri - INFN Seminar
July 7, 2009
July 7, 2009 L.Lanceri - INFN Seminar 2
Flavour physics, a discovery tool
Some past (Standard Model) successes:
Beyond SM with flavour physics?
1970: charm from K0 μ+μ (GIM)
1973: 3rd quark family from K (Kobayashi & Maskawa)
Early 90’s: heavy top from mB
2001: CP in B decays (BaBar & Belle)
2008: Nobel (Kobayashi & Maskawa)
Indirect searches: virtual effects, “loop” corrections
Large “New Physics” effects expected
(SM weak interactions CP, FCNC: in loops)
July 7, 2009 L.Lanceri - INFN Seminar 3
Electrons: E = 9.1 GeV, I = 2.0 A
Positrons: E = 3.0 GeV, I = 3.2 A
Peak luminosity:L = 12 1033 cm-2s-1 =
= 12 events nb-1s-1
Asymmetric-energy e+e- colliderECM = 10.26 GeV
e+e 4S( ) BB ( ) 1nb =10 33cm2
July 7, 2009 L.Lanceri - INFN Seminar 4
BaBar @ PEP-II, Belle @ KEK-B
July 7, 2009 L.Lanceri - INFN Seminar 5
DIRC (PID)
144 quartz bars
11000 PMs
1.5T solenoid
EMC
6580 CsI(Tl) crystals
Drift Chamber
24 stereo layers
16 axial layers
Instrumented Flux Return
iron / RPCs (muon / neutral hadrons)Silicon Vertex Tracker
5 layers, double sided strips
e+ (3.1GeV)
e- (9GeV)
BaBar Detector
Inner layer:
10μm resolution
Fish-eye view of “typical” event:( )
July 7, 2009 L.Lanceri - INFN Seminar 6
DIRC (PID)
144 quartz bars
11000 PMs
1.5T solenoid
EMC
6580 CsI(Tl) crystals
Drift Chamber
24 stereo layers
16 axial layers
Instrumented Flux Return
iron / RPCs (muon / neutral hadrons)Silicon Vertex Tracker
5 layers, double sided strips
e+ (3.1GeV)
e- (9GeV)
BaBar Detector
Inner layer:
10μm resolution
Fish-eye view of “typical” event:( )
Many topics in CP and flavor physics
B decays, CP asymmetries ACP
B decay rates & branching fractions
Charm decays, D0-D0 mixing
lepton decays
Spectroscopy of bound quark states, QCD
2001-2009: > 400 papers
July 7, 2009 L.Lanceri - INFN Seminar 7
Standard Model: CP 3 ”Flavors”
+W
ijgV
tcuqi
,,=
bsdq j ,,=
=
tbtstd
cbcscd
ubusud
VVV
VVV
VVV
V
+W
ub
W
b u
ubV
ubV
CP
“mirror”
a phase in the “CKM” matrix Vij violates CP !
July 7, 2009 L.Lanceri - INFN Seminar 8
CKM matrix: Unitarity Triangle
u
c
t
d s b 3 quark “families”
Mixing:3 3 unitary matrix
4 parameters
(1 complex phase)
July 7, 2009 L.Lanceri - INFN Seminar 9
CKM matrix: Unitarity Triangle
u
c
t
d s b
=tdub
VV argarg
July 7, 2009 L.Lanceri - INFN Seminar 10
CKM matrix: Unitarity Triangle
Just 4 parameters…
… predict
many observables
Observables:
Branching Fractions
and B-B Mixing ( “sides”)
example:
semi-leptonic decay rates
for B mesons
BF Bd0 D l+( ) Vcb
2
BF Bd0 l+( ) Vub
2
W +
b c Vcb
d d
l+
July 7, 2009 L.Lanceri - INFN Seminar 11
CKM matrix: Unitarity Triangle
Just 4 parameters…
… predict
many observables
Observables:
Branching Fractions
and B-B Mixing ( “sides”)
example:
semi-leptonic decay rates
for B mesons
BF Bd0 D l+( ) Vcb
2
BF Bd0 l+( ) Vub
2
W +
b c Vcb
d d
l+
July 7, 2009 L.Lanceri - INFN Seminar 12
CKM matrix: Unitarity Triangle
Just 4 parameters…
… predict
many observables
Observables:
CP Asymmetries( “angles” = phases)
interference needed ! Ex.:
“double slit” experiments
W +b c
Vcb
d d
cs
Wb d
Vtd
d b
JB0
W
t
tB0 B 0
K 0
July 7, 2009 L.Lanceri - INFN Seminar 13
CKM matrix: Unitarity Triangle
Just 4 parameters…
… predict
many observables
Observables:
CP Asymmetries( “angles” = phases)
interference needed ! Ex.:
“double slit” experiments
W +b c
Vcb
d d
cs
Wb d
Vtd
d b
JB0
W
t
tB0 B 0
K 0
: KS , …
: , ,
: D( )K( ) , …
July 7, 2009 L.Lanceri - INFN Seminar 14
Unitarity Triangle: today
Statistically compatible with
the Standard Model (SM)
Cosmology, dark matter, etc.:
“new” physics beyond the SM !
Any hint in the data?
“Waiting for Godot”…a few 2 effects:
BF( ) vs. sin2 cc
ACP( K+ , K± 0)
(sin2 : KS vs. KS)
sin2 s from s (CDF)… Godot did not come yet!
July 7, 2009 L.Lanceri - INFN Seminar 15
Another example: charm mixingWilkinson, FPCP 2009:
July 7, 2009 L.Lanceri - INFN Seminar 16
BaBar-Trieste 1995-2009
Contributions from:
Marco Bomben, Cristiano Borean, Luciano Bosisio, Tina Cartaro,
Giuliano Castelli, Fabio Cossutti, Giuseppe Della Ricca, Selenia Dittongo,
Benigno Gobbo, Sergio Grancagnolo, Livio Lanceri, Alexis Pompili,
Paolo Poropat, Michela Prest, Cristiano Rastelli, Irina Rashevskaya,
Davide Scarabino, Erik Vallazza, Lorenzo Vitale, Gloria Vuagnin
(Theory advice: Nello Paver, Guido Michelon)
SVT
BF (B D l ), |Vcb|
sin2 : ACP (B D +D )
BF (B )
D mixing (D K )
sin2 : ACP (B DCP( )0h0)
detector physics
July 7, 2009 L.Lanceri - INFN Seminar 17
Flavour physics: what next?
2010 - 2015: Tevatron LHC (LHCb, …)
sin2 s from s , down to SM value
BF ( s μ+μ ), down to SM value
UT angle down to 2-3o
… etc.
2015 - 2020: e+e “super flavour-factories” ?
physics case: “New Physics” reach
accelerator: lumi. 1036 cm-2 s-1
75 ab-1 in 5 yr, polarization
detector upgrades
July 7, 2009 L.Lanceri - INFN Seminar 18
Physics case in one slide
• New Physics (NP) expected beyond SM
– Scale ? 0.5, 1, 10, … 1016 TeV ?
– Quantum stabilization of EW scale suggests 1TeV
• Two scenarios
– LHC finds NP: SuperB measures couplings, flavour structure,
+ searches heavier states indirectly
– NP above LHC reach: SuperB looks for indirect signals, up to10 TeV or more
• Complementary to LHC
– Test CP, CPT and Lepton Flavour Violation (LFV) in decays
– Many rare B decays only accessible to SuperB
– Sensitive to off-diagonal terms in squark mixing matrix
– Search for CP and CPT violation in D decays
July 7, 2009 L.Lanceri - INFN Seminar 19
Backbone: CKM at 1%M.Ciuchini
Standard ModelStandard Model
July 7, 2009 L.Lanceri - INFN Seminar 20
Lepton Flavour Violation
July 7, 2009 L.Lanceri - INFN Seminar 21
Lepton Flavour Violation
superB
sensitivity
in 75 ab-1
an example:
Minimal Flavour Violation (MFV)
extensions of the SM
July 7, 2009 L.Lanceri - INFN Seminar 22
SUSY? MSSM parameters
the Brave New World
July 7, 2009 L.Lanceri - INFN Seminar 23
SUSY? squark mixing matrix
July 7, 2009 L.Lanceri - INFN Seminar 24
squark couplings: an example
M.Ciuchini
July 7, 2009 L.Lanceri - INFN Seminar 25
Just two rare B decays examples
B K μ+μ
B (μ)
July 7, 2009 L.Lanceri - INFN Seminar 26
B physics @ U(4S)
Possible also at LHCb
Similar precision at LHCb
As in CDR, some number updated on Valencia
July 7, 2009 L.Lanceri - INFN Seminar 27
physics
Bs at U(5S)
Charm at U(4S) and threshold
To be evaluated
at LHCb
Bs : not discussed today. Maybe to be
Revisited for next Workshops
July 7, 2009 L.Lanceri - INFN Seminar 28
“Golden” channels ?
The GOLDEN channel for the given scenario
Not the GOLDEN channel for the given scenario
but can show experimentally measurable deviations
from SM.
Where –CKM means that Lattice improvement are crucial
X
O
work ongoing
to extend and refine
this table
for the TDR
July 7, 2009 L.Lanceri - INFN Seminar 29
Complementarity with LHCb
July 7, 2009 L.Lanceri - INFN Seminar 30
SuperB: concepts
Design principles
Lumi 100 !?!
July 7, 2009 L.Lanceri - INFN Seminar 31
SuperB new features
“crab waist”
Sextupoles
on
July 7, 2009 L.Lanceri - INFN Seminar 32
SuperB parameters
July 7, 2009 L.Lanceri - INFN Seminar 33
Alternative LNF site
July 7, 2009 L.Lanceri - INFN Seminar 34
Detector: partially BaBar
July 7, 2009 L.Lanceri - INFN Seminar 35
SuperB collaboration: TDR
July 7, 2009 L.Lanceri - INFN Seminar 36
Luminosity Prospect
3636
Integrated Luminosity(1/ab)
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
Year 0
Year 1
Year 2
Year 3
Year 4
Year 5
Year 6
Year 7
Year 8
L~2x1035
L~8x1035
50ab-1 by ~2020
10ab-1 ~ 2016
“brute force” “nano-beam”
July 7, 2009 L.Lanceri - INFN Seminar 37
Super
Flavour
Factory
July 7, 2009 L.Lanceri - INFN Seminar 38
The European Strategy for particle physics…
Scientific activities
…
8. Flavour physics and precision measurements at the high-luminosity
frontier at lower energies complement our understanding of particle
physics and allow for a more accurate interpretation of the results at
the high-energy frontier; these should be led by national or regional
collaborations, and the participation of European laboratories and
institutes should be promoted.
Back-up slides
July 7, 2009 L.Lanceri - INFN Seminar 40
Matter-Antimatter
asymmetry
Coming from a tiny
asymmetry of order 10-9:
1,000,000,001q +
1,000,000,000 q
1q + radiation
Origin ??
B
nB nB
n=
nB
n=
= 6.1± 0.3( ) 10 10
Now:
Baryons
photons
No antimatter now!
July 7, 2009 L.Lanceri - INFN Seminar 41
Matter-Antimatter
asymmetry
t 10-34 sec:
“baryogenesis”
Baryon number (B) violation
C and CP violation
Departure from thermal equilibrium
Several possible
mechanisms
All require the violation of the
CP symmetry
C = charge conjugation
P = parity
July 7, 2009 L.Lanceri - INFN Seminar 42
Example of “double-slit” experiment
e i2
B0 fCP
Af
AfB0
Flavor-tagged time-dependent decay rates expected to be different!
Asymmetries proportional to CKM phase differences through S
Interference between mixing and decay to a CP eigenstate CPf
B0 fCP
B0
Af
Afei2
CP“mirror”
B0 tag
B0 tag
t( ) e t 1+ CPS sin m t( )[ ]
t( ) e t 1 CPS sin m t( )[ ]
t/Challenges:
Rare decays: BF 10 4÷10 6
Flavor tagging by “other B”Time resolution: 1 ps
July 7, 2009 L.Lanceri - INFN Seminar 43
e
( )4S+
e
Coherent BB
production
(p-wave)
B0
B0
tagB
0recB
0
B-Flavor
tagging0.3Q
μ
K
Reconstruction of Bdecays to exclusive
final states
μμ+
+KS0
J
(4 )/S
z c t
z
An example of CP Asymmetry MeasurementB-flavor tagging efficiency and t resolution function are obtained from data(measurement of mixing, with exclusively reconstructed self-tagging flavorstates)
July 7, 2009 L.Lanceri - INFN Seminar 44
CP violation observed!383 106 4S( ) BB events
12677 events with b cc s (7 modes)
75% purity
S = sin2 = 0.714 ± 0.032 ± 0.018
B and B behave differently!
beautiful interference pattern observed,
as predicted by the Standard Model
383 106 4S( ) BB events
340 ± 32 B DCP0(*)h0 events
S = 0.56 ± 0.23± 0.05
“new physics”? (i.e. SUSY models)
should appear in rare suppressed decays
Example:
July 7, 2009 L.Lanceri - INFN Seminar 45
Integrated luminosity
(4S):
466,000,000 BB
recorded
Y(3S): 30.2 fb-1 Y(2S): 14.5 fb-1
above Y(4S): ~5 fb-1
July 7, 2009 L.Lanceri - INFN Seminar 464646
SpectroscopySpectroscopy
M(M
eV)
JPC
(2S+1)LJ
Open charm thr. (3770)
(4040)
(4160)
(pot. Models)c
’c
J/
’c2
c1
c0
hc
X Z
X,YX(3872) the
best
tetraquark
candidate
Updated properties
(4415)
The 1-- family:
Charmonia,
tetraquarks,
molecules,
hybrids?!?
News on the
3940 family
+ updates on
Y(nS) Y(mS)
transitions
Yet
another
particle:
X(4160)[ c(3S)?]
Z(4430): the first
charged state
July 7, 2009 L.Lanceri - INFN Seminar 474747
The observation matrixThe observation matrix
J/J/ ++ DD(*)(*)DD(*)(*) J/J/ J/J/ ++ 00 (2S)(2S) J/J/ K,K, (2(2SS)) J/J/ ,, J/J/
NotesNotes MassMass
rangerange
for Bfor B
LowLow
statstatOnlyOnly
B decB decMassMass
range!range!
No ISRNo ISR
No ISRNo ISR
No No 00
NoNo
SearchSearchNo B-No B-
decdecOnly BOnly B
decdecMassMass
windowindo
ww
X(3872)X(3872) SeenSeen SeenSeen NotNot
seenseenNot seenNot seen Not seenNot seen NoNo
searchsearchN/AN/A NotNot
seenseenSeenSeen
Y(3940)Y(3940) NoNo
searchsearchX(3940)X(3940)
??SeenSeen No searchNo search Not seenNot seen NoNo
searchsearchNoNo
searchsearchNo FitNo Fit No fitNo fit
Y(4260)Y(4260) SeenSeen No fitNo fit No fitNo fit No searchNo search NoNo
searchsearchNoNo
searchsearchNot seenNot seen No fitNo fit N/AN/A
Y(4350)Y(4350) NotNot
seenseenNo fitNo fit No fitNo fit No searchNo search NoNo
searchsearchNoNo
searchsearchSeenSeen No fitNo fit N/AN/A
Z(4430)Z(4430) NoNo
searchsearchNoNo
searchsearchNo fitNo fit No searchNo search SeenSeen NoNo
searchsearchNoNo
searchsearchNo FitNo Fit NoNo
searcsearc
hh
Y(4660)Y(4660) NotNot
seenseenNo fitNo fit No fitNo fit No searchNo search NoNo
searchsearchNoNo
searchsearchSeenSeen No FitNo Fit N/AN/A
July 7, 2009 L.Lanceri - INFN Seminar 48
Flavor factories in the future?
Physics: 100 increase in luminosity would give access to quantum
effects (loops) of new particles and couplings in the TeV range, with
information complementary to LHC
Accelerator: very challenging!
INFN is evaluating a “SuperB”
Project for a “regional” lab with
an asymmetric 1036 “flavor factory”
Lepton Flavor Violation
July 7, 2009 L.Lanceri - INFN Seminar 49
Mini-MAC requirements
Parameter Requirement Comment
Luminosity (top-
up mode)
1036 cm-2s-1 @ (4S)
Integrated
luminosity
75 ab-1 Based on a “New Snowmass
Year” of 1.5 x 107 seconds
(PEP-II experience-based)
CM energy range From just below charm threshold to (5S)
For a better study of CP violation
in Charm and for BS
measurements.
Minimum boost = 0.28 (4x7 GeV) 1 cm beampipe radius. First
measurement at 1.5 cm
e- Polarization 60-85% Enables CP and T violation
studies, measurement of g-2
and improves sensitivity to
lepton flavor-violating decays.
Detailed simulation, needed to
ascertain a more precise
requirement, are in progress.
July 7, 2009 L.Lanceri - INFN Seminar 505050
2007 2008 2009 2010 2011 2012
KEKB
ILC R&D
Photon Factory& upgradeoperation
LHC
J-PARC
ERL R&D
July 7, 2009 L.Lanceri - INFN Seminar 51
Physics Case
..en pillule…
SuperB+Lattice improvements
tan
tan
SuperB
MH~1.2-2.5 TeVfor tan ~30-60
23| |LR
1 10
1
10-1
10-2
(TeV)gluinom
In the red regions the
are measured with a
significance >3 away
from zero
23| |LR
Arg( 23)LR=(44.5± 2.6)o
= (0.026 ± 0.005)
1 TeV
10
7 BR
(μ)
M1/2
SuperB