Upload
noah-bailey
View
214
Download
0
Embed Size (px)
Citation preview
From Belle to a Super B Factory
• Introduction+Background+History• New Physics in Loops (more motivation) • bs Penguins (2 or 3 examples)• Decays with “Large Missing Energy”• How the Super B Factory fits in
Apologies: Will aim at HEP physicists outside of B physics. “If I could remember all the decay modes I would have been a botanist” . Only a small subset of possible results.
I
Tom Browder (University of Hawaii)
Weak Interaction coupling constants
Wolfenstein parameterization: Observed experimental hierarchy
2 3
2 2
3 2
1 / 2
1 / 2
1 1CKM
A i
V A
A i A
us ubud
csCKM cbcd
ts tbtd
V V V
V V V V
V V V
KM Phase: changessign under CP
2x2 submatrix: u,d,s,c quarks only
~ 0.22sinθC
Cabibbo angle3x3 matrix: 3 quark generations
2 1~
3 2~2
3 1~3d s b
u
c
t
d s bu
c
t
magnitudes phases
Three Angles: (φ1,φ2,φ3) or (β, α,
γ)
B0Ψ Ks,Ψ KLB- DCP K-
B0 π- π+
Big Question(s): Are determinations of angles consistent with determinations of the sides of the triangle ? Are angle determinations from loop and tree decays consistent ?
Unitarity implies that the weak couplings and phases form a triangle in the complex plane.
Time Dependent CPV in B0 decays
Mixing-induced CPVMixing-induced CPV Direct CPVDirect CPV
e.g. for BJ/ KsS = CPsin21 = +sin21 A ~ 0
(CP : CP eigenvalue 1)
e.g. for BJ/ KsS = CPsin21 = +sin21 A ~ 0
(CP : CP eigenvalue 1)
N.B. Time integrated mixing-induced asymmetries vanish
)cossin(141
,1 tmAtmSetqPt
)21( w
R
R : detector resolutionw : wrong tag fraction (misidentification of flavor) (1-2w) quality of flavor tagging These are well determined by using data control samples: D*l D(*) etc…
S = 0.65A = 0.00 B0 tag
_B0 tag
B0 tag_B0 tag
-CPsin21
D*lMixing data
(OF-
SF)/(
OF+
SF)
t| (ps)
Experimental Complications (MC)
e+ source
Ares RF cavity
Belle detector
World record: L = 1.7 x
1034/cm2/sec
SCC RF(HER)
ARES(LER)
The KEKB Collider (Tsukuba, Japan)
8 x 3.5 GeV 22 mrad crossing angle
Corkheads Australian Bar
2006: Integrated Luminosity Milestone at the B factories
PEP-IIfor BaBar
KEKBfor Belle
KEKB + PEP-II
reached on July 13, 2006
~ 1 Billion BB pairs
Inte
grat
ed L
umin
osit
y (f
b-1)
May be time to switch units to ab-1
535 x 106 B pairs used for results
/ KL detection 14/15 lyr. RPC+Fe
Tracking + dE/dx small cell + He/C2H6
CsI (Tl) 16X0
Aerogel Cherenkov cnt. n=1.015~1.030
Si vtx. det. 34 lyr. DSSD
TOF counters
SC solenoid1.5T
Belle DetectorBelle Detector
8GeV e
3.5GeV e
Slovenia groups +Background monitors
Example of a Fully-reconstructed Event
Some recent history: Summer of 2001
Belle:
BaBar:
The first example of CP Violation outside of the kaon system.
CP Violating Effects of O(1) rather than O(10-3)
B0 J/ KS
B0 tag_B
0 tag
0 B0 J/ KL
B0 tag_B0 tag
0
Asym. = -CPsin21sinmt
sin21= +0.643 ±0.038 A = - 0.001 ±0.028
sin21= +0.641 ±0.057 A = +0.045 ±0.033
stat error stat error
hep-ex/0608039hep-ex/0608039backgroundsubtracted
2006 Data
B0 J/ KS
B0 tag_B
0 tag
0 B0 J/ KL
B0 tag_B0 tag
0
B0 tag_B
0 tag
B0 J/ K0 : combined result
Asym. = -CPsin21sinmt
sin21= +0.643 ±0.038 A = - 0.001 ±0.028
sin21= +0.641 ±0.057 A = +0.045 ±0.033
stat error stat error
B0 J/ K0 : combined result 2006
sin21= 0.642 ±0.031 (stat) ±0.017 (syst) A = 0.018 ±0.021 (stat) ±0.014 (syst)
previous measurementsin2= 0.652 0.044
(388 M BB pairs)
B0 tag_B
0 tag
535 M BB pairs_ _
hep-0608039/ to appear in PRLhep-0608039/ to appear in PRL
sin21 : 2006 BaBar + Belle
Now a precise measurement < 4 % error
Reference Point for NP search
0.674 0.026
Av. C = A = 0.012 0.022
Q. What is the main source of CP violation ?
A. Consistency of sin(2φ1)with indirect measurementsshows that Kobayashi-Maskawaphase is the dominant source !
sin2sin(2φ1) history(1998-2005)
Q. Are there deviations from the CKM picture ? (e.g. new CP-violating phases, new couplings)
Paradigm shift
Consistency between measurements of angle and sides
New Physics
Are there new particles beyond those in the SM, which have different couplings (either in magnitude or in phase) ?
Supersymmety is an example (~40 new phases)
How to find New Physics Phases
Example:Vts: no KM phase
SM: sin21 = sin21 from BJ/ K0 (bc c s)
unless there are other, non-SM particles in the loop
eff
Vtd
Vtd
+
1
B B
, ’,
1
, ’,
_
*
*
How New Physics may enter in bs
0SK
0B
b
s
s
sd d
0SK
0B
b
s
s
sd d
Many new phases are possible in
SUSY
New physics in loops?
Extra dimensions (by Randall + Sundrum)
New Kaluza-Klein (K.K) particles are associated with the extra dimension.
(“Tower of states”)
Some may induce new phases and flavor-changing neutral currents.
e.g. K.Agashe, G. Perez, A. Soni, PRD 71, 016002 (2005)
Model: K.K. Gluon near 3 TeV
RS1
SM
++CPV in D decay
e.g. G. Burdman, Phys Lett B 590, 86 (2004)
Belle 2006: tCPV in B0 K0
“sin21” = 0.50 0.21(stat) 0.06(syst) “sin21” = 0.50 0.21(stat) 0.06(syst)
KS and KL combined background subtracted good tags t –t for KL
t distributions and asymmetry
_535M BB
Consistent with the SM (~1lower) Consistent with Belle 2005
(Belle2005: “sin21” = +0.44
Consistent with the SM (~1lower) Consistent with Belle 2005
(Belle2005: “sin21” = +0.44
unbinned fitSM
hep-ex/0608039, PRL 98, 031802(2007)
hep-ex/0608039, PRL 98, 031802(2007)
a.k.a sin(2β)
K0: sin2eff = +0.12 ± 0.31(stat) ± 0.10 (syst)K0: sin2eff = +0.12 ± 0.31(stat) ± 0.10 (syst)
BaBar: K0 using B0 K0
measurement (not sin2)
[hep-ex/0607112] _347M BB
a.k.a. sin(2 φ1)
unbinned fitSM
“sin21” = 0.64 0.10 0.04“sin21” = 0.64 0.10 0.04
535M BB 5.65.6
’K0
“sin21” = 0.58 0.10 0.03 “sin21” = 0.58 0.10 0.03
>5>5
’Ks ’KL
_347M BB
[hep-ex/0608039]PRL 98,031802(2007) [hep-ex/0607100], PRL+Sept 28 press conf
1st Observation of tCPV in a bs mode
2006: Hints of NP in b s Penguins ?
Smaller than bccs in all of 9 modes
Smaller than bccs in all of 9 modes
Theory predicts positive shifts
Naïve average of all b s modes
sin2eff = 0.52 ± 0.052.6 deviation from SM
Naïve average of all b s modes
sin2eff = 0.52 ± 0.052.6 deviation from SM
Results on Radiative and Electroweak Penguins
Example discussed here: modifications to the rate for bs γ
Measurement of inclusive b sγ
Measure primary only:monochromatic E spectrum
Important to measure low E to reduce model dependence
Huge Background (semi-log) experimental challenge
Background suppression• continuum: event shape• veto
Nakao
NNLO calculation
(29826) x 10-6
M. Misiak et al, hep-ph/0609232, PRL 98,022002(2007)
Theory News
Error on BF
Central value of BF
95% CL lower limit on charged Higgs mass from exp and NNLO
M. Misiak et al, hep-ph/0609232, PRL 98,022002 (2007)
Right-handed currents in b s
• tCPV in B0 (Ks0)K*
– SM: is polarized, the final state almost flavor-specific.
S(Ks0 ~ 2ms/mbsin21
– mheavy/mb enhancement for right-handed currents in many new physics
models
e.g. LRSM, SUSY, Randall-Sundrum (warped extra dimension) model
– LRSM: SU(2)LSU(2)RU(1)
• Right-handed amplitude mt/mb : is WL-WR mixing parameter
• for present exp. bounds (WR mass > 1.4TeV)
|S(Ks0 ~ is allowed.
– No need for a new CPV phase
b
b
Ls
Rs
mb
mb
msms
D.Atwood, M.Gronau, A.Soni, PRL79, 185 (1997)D.Atwood, T.Gershon, M.H, A.Soni, PRD71, 076003 (2005)
Photon polarization measurementvia time dependent CPV !
Photon polarization measurementvia time dependent CPV !
_232M BB
Status of B KS 0γ tCPV Status of B KS 0γ tCPV
Yield = 176+/- 18
535M BB M(Ks 0) < 1.8 GeV
(C)hep-ex/0608017, PRD-RC 74, 111014(2006)hep-ex/0608017, PRD-RC 74, 111014(2006)
No new physics but errors on S are large
Rare Decays with Large “Missing Energy”
Motivation for B++ν
Sensitivity to new physics from charged Higgs if the B decay constant is known
The B meson decay constant, determined by the B wavefunction at the origin
Why measuring νis non-trivial
(4S)B- B+
e+
e
B++, +e+e
B-X
The experimental signature is rather difficult: B decays to a single charged track + nothing
Most of the sensitivity is from tau modes with 1-prong
Example of a B ν candidate
Tag: BD0 ,
D0 K
Very difficult or impossible at a hadron collider
Evidence for B+ ν (Belle)
Find signal events from a fit to a sample of 54 events.
4.6 stat. significance w/o systematics,
449 106 B pairs BtagD(*)[,a1,Ds(*)] 680k tags, 55% pure. 5
decay modes
5.34.717.2
MC studies show there is a small peaking bkg in the 0 and modes.
After including systematics (dominated by bkg), the significance decreases to 3.5σ
Extra Calorimeter Energy
Direct experimental determination of fB • Product of B meson decay constant fB and CKM
matrix element |Vub|
• Using |Vub| = (4.39 0.33)×10-3 from HFAG
fB = 216 22 MeV (an unquenched lattice calc.)
[HPQCD, Phys. Rev. Lett. 95, 212001 (2005) ]
36 3431 37229Bf MeV
( Belle)
1.6 1.3 41.4 1.4(10.1 ) 10B ubf V GeV
Theory:
(PRL 97, 251802 (2006))
Constraints on charged Higgs mass
rH=1.130.51
Use known fB and |Vub |
Ratio to the SM BF.2
2 22
(1 tan )BH
H
mr
m
excluded
excl
uded
449M
Compare to direct searches for H+
New result announced in Bled, Slovenia
Seems to confirm the Belle result
Another charged Higgs constraint: B D(*)
• Semileptonic tauonic decays
cb
H/W
tan cotb cm m
tanm
( )
( )
B D vB
B D v
Br(SM)~ 8 x 10-3
– Ratio (/) is modified by the charged Higgs effect.– Provide good cross check to B– Y.Okada
• H-b-u vertex measured in B• H-b-c vertex measured in BD• H-b-t vertex measured in direct production by LHC.
Reconstruction of B D(*)
New Belle Result Announced in Bled, Slovenia
Potential sensitivity of B D(*) to H±
Similar to B
5ab-1
FF=15%50ab-1
FF=5%
B K(*) : Motivation
b s with 2 neutrinos
SM: B(BK* ) ~1.3 x 10-5 B (BK ) ~4 x 10-6 (Buchalla, Hiller, Isidori)
PRD 63, 014015
DAMA NaI 3Region
CDMS 04
CDMS 05
No sensitivity to M<10 GeV in direct searches
• New Physics in Loop• Light Dark Matter (M~1GeV)
_
_
_
New Belle Result announced in Bled, Slovenia
New Belle Result announced in Bled, Slovenia
Super B Factory LOI: with present level of detector hermicity, 5σ observation of BK will be possible with 50 ab-1
Implications for light dark matter
Comments on Super B Factories(political comments are in the backup slides)
The Super B Factory is part of a Unified and Unbiased Attack on New Physics
Newphysics
Quark sectorLepton sectorPr
opag
ator
s
expts accel, reactor,g-2, e, etc.
Super B Factory, LHCb, Rare K expts, BESIII…
LHC, ILC
mass and mixing,CPV, and LFV
Higgs boson massand couplings. New particle searches
Flavor mixing,CPV phases
LFV, CPV
Are there New Physics Phases and New sources of CP Violation Beyond the SM ?
Are there right-handed currents ?
Are there new flavor changing neutral currents ?
Are there new operators with quarks enhanced by New Physics ?
Fundamental Questions in Flavor Physics
Experiments: bs CPV, compare CPV angles from tree and loops
Experiments: AFB(BK*l l), BK rates and asymmetries
Experiments: bs CPV, B->VPγ or BV V triple-product asymmetries
Experiments: bs ννbar, D-Dbar CPV+mixing+rare, τγ
These questions can only be answered at a Super B Factory.
Why three generations ?
String Theory ? (e.g. P.Binetruy et.al.,
hep-th/0509157; J.Phys G.32: 129 (2006)); Larger Symmetry Groups ?
Experiments with quarks or heavy leptons?
This question is probably too hard – more tractable questions…..
Lessons of History New Physics is usually discovered first in loop
processes, which involve high mass virtual particles. (Heisenberg Uncertainty Principle)
Beautiful and precise measurements of the top quark mass at the Tevatron. However, the couplings |Vts|, |Vtd,| and most importantly the phase of (Vtd) cannot be measured in direct top production.
Example I: Absence of KL allowed theorists to deduce the existence of the charm quark. The rate of K mixing allowed a rough determination of the charm mass.
Example II: The absence of bs decays and the long B lifetime ruled out topless models. Large Bd mixing showed the top was heavy contrary to theory prejudices of the time. Radiative corrections from Z measurements determined the rough range of the top mass.
Vtd
Vtd
Recent Developments for the Super B Factory Accelerator
SuperKEKB design luminosity is now 8 x 1035/cm2/sec
Low emittance/ILC inspired INFN/SLAC design is ~10 x 1035/cm2/sec
To address the full array of new physics searches, require ~50 ab-1 of integrated luminosity
c.f. Current KEKB luminosity is 1.7 x 1034/cm2 /sec
c.f. Current KEKB integrated lumi 0.7 ab-1
Interaction RegionCrab crossing
=30mrad.y*=3mm
New QCS
Super B Factory at KEK
Linac upgrade
More RF power
Damping ring
New Beam pipe
Ante-chamber & solenoid coilsto reduce photo-electron clouds
L = 81035/cm2 /sec
Question: 12 nanometer beam spot in y, 2.7 microns in x. Is this possible in a real 2-3 km circumference multi-orbit machine ?
Conceptual Design Report has been submitted to INFN.
First step towards Super B: Crab crossing
. Superconducting crab cavities (1 LER and 1 HER) have been installed and now are being tested at KEKB.
Crab Cavities have been installed in the KEKB tunnel (1 cavity per ring)
LER (3.5 GeV, positron) HER (8 GeV, electron)
Specific Luminosity at KEKB
22 mrad finite-crossing
Crab-crossing
The highest beam-beam is ~0.08.
Before crab,beam-beam is 0.052.
Summary of current KEKB StatusThe crab cavities were successfully assembled and have been operated at KEKB with beam. No serious problem has been found so far, at least at low current.
The first crab crossing was done at KEKB. (~30 years after the idea was first proposed by Bob Palmer) Head-on collision with a crossing angle was
achieved. Large gains in physics luminosity will require more time for tuning and development of method to optimize the machine since a higher beam-beam parameter is very sensitive to machine errors.
Requirements for the detector
- low p identification s recon. eff.- hermeticity “reconstruction”
- radiation damage and occupancy- fake hits and pile-up noise in the EM
- higher rate trigger, DAQ and computing
Issues: Higher background ( 20)
Higher event rate ( 50)
Required special features
Possible solution: Replace inner layers of the vertex detector with a silicon striplet detector. Replace inner part of the central tracker with a silicon strip detector. Better particle identification device Replace endcap calorimeter by pure CsI. Faster readout electronics and computing system.
Possible solution: Replace inner layers of the vertex detector with a silicon striplet detector. Replace inner part of the central tracker with a silicon strip detector. Better particle identification device Replace endcap calorimeter by pure CsI. Faster readout electronics and computing system.
Detector issue: backgroundsDetector issue: backgrounds
KEKB SuperB
Luminosity(1034cm-2sec-1)
1.7 80
HER curr. (A)
LER curr. (A)vacuum (10-7Pa)
1.2
1.6
~1.5
4.1
9.4
5
Bkg increase - x 20
TRG rate (kHz)phys. origin
Bkg origin
0.40.2
0.2
1410
4Shynchrotoron radiationBeam-gas scattering (inc. intra-beam scattering)Radiative Bhabha
SVD CDC PID / ECL KLM
KEKBBkg
x10 Bkg
x20 Bkg
~ 20
Super Belle: A detector for SuperKEKB
New dead time free pipelined readout and
high speed computing systems
Faster calorimeter with waveform sampling and pure CsI crystal
New particle identifier with precise Cherenkov device:S.Korpar, P. Krizan et al.
Si vertex detector withhigh background
tolerance: S. Stanic et al.
Background tolerant super small celltracking detector
KL/ detectionwith scintillator
and new generationphoton sensors
Backup Slides
http://www.jahep.org/hec/doc/jahep_tenbou_eng_final.pdf
....
(An excerpt)
“Dai-repoton keikaku”
K. Oide (Leading Japanese Accelerator Physicist)
Official Announcement from KEK director A. Suzuki on Super B expected in 2007
Budget of Japanese
accelerator physicists
Milestones toward approval
KEK’sdecision MEXT MOF
Japanese HEP community
LoIJune 2004
Support from theint’l HEP community
Academy of Science
Review panel
CSTP
Review committee
Recommendation by Belle-PAC• The committee provided a strong endorsement for
SuperKEKB at the meeting in April 2007.
This is also an important support from the int’l community.
2006 2008 2010 2012 2014 2016 2018 2020
PF upgrade PF
Budget transfer
ERL prototype
ERL construction experiment
KEKB
ILC R&D
ILC construction experiment
Budget transfer
Budget transfer
Option 1
KEKB
ILC R&D
ILC construction experiment
KEKB upgrade experiment
Budget transfer
Option 1’
J-PARC , n construction
J-PARC R&D
J-PARC , K experiment
J-PARC n, experiment
upgrade
Budget transfer
As in bs γ, heavy particles in the loops can be replaced with NP particles (e.g.W+ H+)
The Hunt for the EW Penguin:BXs l+ l-
Note contributions from virtual γ* , W, Z*
and internal t quark.
Discovered by CLEO in 1994
B → XB → Xsγ from a sum of 38 exclusive decay modes
Eγ>1.9 GeV
hep-ex/0508004, 88.9 MBB
b s : Belle result140fb-1Efficiency corrected spectrum
E >1.8 GeV (cover 95.2%)
B(B s ) = (3.55 0.32 ) x10-4 +0.30 +0.11
0.31 0.07(Stat) (sys) (theo)
<E> = 2.292 0.0260.034 GeV
<E> <E> = 0.0311 0.0730.063 GeV
[hep-ex/0403004, PRL xxx]
Moments:
useful for Vcb,Vub
An update with much more data (x 3) is in progress
SuperKEKB Projection for B Ks0 and other b smodes
Possible deviationO(1): Warped extra dim.O(1): L-R symmetric modelO(0.1): SUSY SU(5)
B K0, ’K0, KsKsKs projection for SuperKEKB
total errors(incl. systematicerrors)
b s : Bkg subtraction
Continuum use OFF-resonance data (ECM 60 MeV lower)
B background B X: measured by data include in MC
backup
The Super B Factory will face tough competition from LHCb, which is now a real experiment.
LHCb
There is considerable complementarity: photon, neutral detection and inclusive channels are considerable easier at the Super B Factory while time-dependent Bs studies are superior at LHCb.
J. Libby
10 fb-1 for LHCb
50 fb-1 for SuperB
Crab Crossing
Input Coupler
Liq. Helium Vessel
Stub Support
Coaxial Coupler
Copper Bellows
80 K Liq. Nitrogen Shield
Notch Filter
RF Absorber
Aluminum End
Plate
Aluminum End
Plate
SUS Support
Pipe
Crossing angle 30 mrad
Head-on(crab)(Strong-strong simulation)
Crab crossing will boost the beam-beam parameter up to 0.2!
Superconducting crab cavities have beenproduced, and are now being tested at KEKB.
(at the optimum tune)
Vert
ical beam
-beam
2 cavities/ring K. Hosoyama, et al.
K. Ohmi, et al.
Intriguing Tension between |Vub| and sin(2φ1)tree loop
Small non-zero NP phase
Amplitude close to 1