A. Drutskoy, - PowerPoint PPT Presentation

About This Presentation
Title:

A. Drutskoy,

Description:

Results and prospects of Y(5S) running at Belle. A. Drutskoy, University of Cincinnati LPHE seminar March 14, 2008, Lausanne, Switzerland. LPHE seminar Results and ... – PowerPoint PPT presentation

Number of Views:62
Avg rating:3.0/5.0
Slides: 41
Provided by: Departme216
Category:

less

Transcript and Presenter's Notes

Title: A. Drutskoy,


1
Results and prospects of Y(5S) running at Belle.
A. Drutskoy, University of Cincinnati
LPHE seminar
March 14, 2008, Lausanne, Switzerland.
LPHE seminar Results and prospects of
Y(5S) at Belle, March 14, 2008 ,
Lausanne A. Drutskoy
2
Outline
2
Introduction.
Recent Belle measurements at Y(5S).
Prospects of Bs meson (and other) studies at
Y(5S).
My thoughts (speculations) about Y(5S) -gt Y(6S)
-gt .
Conclusion.
3
e e- hadronic cross section
3
-
-
-
-
-

(cc,ss,uu,dd)
bb
?(4S)
e
B
_
B
e-
?(6S)
Resonance to continuum hadron production ratios
are Y(4S)/Cont 1./3.5 and Y(5S)/Cont 1./10.
4
Running at Y(4S) and Y(5S)
4
?(4S)
Asymmetric energy ee- colliders (B Factories)
running at Y(4S) Belle and BaBar
1985 CESR (CLEO,CUSB) 0.1 pb-1 at Y(5S)
2003 CESR (CLEO III) 0.42 fb-1 at Y(5S)
2005 Belle, KEKB 1.86 fb-1 at Y(5S)
2006, June 9-31 Belle, KEKB 21.7 fb-1 at Y(5S)
_
e e- -gtY(4S) -gt BB, where B is B or B0 meson
_
_
_
_
_
_
_
_
e e- -gt Y(5S) -gt BB, BB, BB, BBp, BBpp, BsBs,
BsBs, BsBs
where B -gt B g and Bs -gt Bs g
G(Y(5S)) 110 ? 13 MeV/c2 (PDG)
M(Y(5S)) 10865 ? 8 MeV/c2 (PDG)
Bs rate is 10-20 gt high lumi ee- collider at
Y(5S) -gt Bs factory.
5
5
First Y(5S) runs at the KEKB ee- collider
Belle
Electron and positron beam energies were
increased by 2.7 (same Lorentz boost bg
0.425) to move from Y(4S) to Y(5S).
8 GeV e-
3.5 GeV e
No modifications are required for Belle
detector, trigger system or software to move
from Y(4S) to Y(5S).
Integrated luminosity of 1.86 fb-1 at 2005
and 21.6 fb-1 at 2006 was taken by Belle
detector at Y(5S). The same luminosity per day
was taken at Y(5S) as it is at Y(4S).
Very smooth
running
6
New 2006 runs at Y(5S) at Belle
6
Belle collected data at Y(5S) June 9-June 31,
2006 gt 21.7 fb-1
Exceeded 1.2fb-1/day for the first time at Y(4S).
Daily luminosity
Correction factor(1.056) is necessary for 5S
run due to smaller Bhabha Cross section.
5S run
22 fb-1
Off-resonance run
7
Integrated luminosity
7
Belle (10 Mar 08) All 778 fb-1 , Cont 68
fb-1 , Y(5S) 24 fb-1
Belle BaBar gt 1 ab-1
8
Hadronic event classification
8
hadronic events at U(5S)
u,d,s,c continuum
b continuum
U(5S) events
N(bb events) N(hadr, 5S) - N(udsc, 5S)
bb events
B0, B events
Bs events
fs N(Bs() Bs()) / N(bb)
Bs Bs
Bs Bs
Bs Bs channel
9
Number of bb events, number of Bs events
9
-
-
-
-
Continuum event yield (uu,dd,ss,cc) is estimated
using data taken below the Y(4S)
Ncont(5S) Ncont(E10.519) L(5S) / L(cont)
(Econt/E5S)2 (e5S/ econt)
Y(5S)
Lumi 1.857 0.001 (stat) fb-1
Cont (below 4S)
3.670 0.001 (stat) fb-1
Nbb(5S)
561,000 3,000 29,000 events
gt 5 uncertainty from luminosity ratio
CLEO Nbb(5S)/ fb-1 310,000 52,000
Nbb(5S) / fb-1 302,000 15,000
How to determine fs N(Bs() Bs()) / N(bb)?
bb at Y(5S)
_
_
B B
Bs Bs
Bf (Y(5S) -gt Ds X) / 2 fs Bf (Bs -gt Ds X)
(1- fs) Bf (B -gt Ds X)
x
x
1. Bf (Bs -gt Ds X) can be predicted
theoretically, tree diagrams, large.
2. Bf (B -gt Ds X) is well measured at the Y(4S).
10
Inclusive analyses Y(5S)-gtDs X, Y(5S)-gtD0X
10
points5S hist cont
points5S hist cont
Y(5S)
P/Pmaxlt0.5
Ds-gt f p
Ds-gt f p
3775 100 ev
D0 -gt K- p
After continuum subtraction and efficiency
correction
Bf (Y(5S) -gt Ds X) 2 (23.6 1.2 3.6)
L 1.86 fb-1
Nbb(5S)
Bf (Y(5S) -gt D0 X) 2 (53.8 2.0 3.4)
561,000 3,000 29,000 events
fs N(Bs() Bs()) / N(bb)
gt
(18.0 1.3 3.2 )
s(Y(5S)-gtbb) (0.302 0.015)nb at E10869MeV
11
Signature of fully reconstructed exclusive Bs
decays
11
BsBs , BsBs , BsBs
MC
Zoom
Mbc vs DE
Mbc vs DE
where Bs -gt Bs g
e e- -gt Y(5S) -gt BsBs, BsBs, BsBs,
Reconstruction Bs energy and momentum, photon
from Bs is not reconstructed.
Mbc Ebeam2 PB2 ,
DE EB Ebeam
Two variables calculated
Figures (MC simulation) are shown for the decay
mode Bs -gt Ds- p with Ds- -gt f p- .
The signals for BsBs, BsBs and Bs Bs can be
separated well.
12
Exclusive Bs -gt Ds() p-/r- and Bs-gt J/y f/h
decays
12
Data at Y(5S), 1.86 fb-1
Bs -gt Ds p-
Bs -gt J/y f/h
Bs -gt Ds p-
Bs -gt Ds() r-
7 evnts in Bs Bs
3 evnts in Bs Bs
9 evnts in Bs Bs
4 evnts in Bs Bs
N(BsBs) / N(Bs()Bs()) (93 79 1)
5.408ltMBClt5.429GeV/c2
Potential models predict Bs Bs dominance over
BsBs and BsBs channels, but not so strong.
Bs Bs
Nev20.3 4.8
Conclusions 1. Belle can take 30 fb-1 per
month. 2. Number of produced Bs at Y(5S) is
105/fb-1. 3. BsBs channel dominates over all
Bs()Bs(). 4. Backgrnds in exclusive modes are
not large.
13
Number of Bs in dataset
13
hadronic events at Y(5S)
bb continuum included
Lumi 1.857 fb-1
bb events
N ev 561,000 3,000 29,000
fs (18.0 1.3 3.2 )
Bs events
N ev 101,000 7,000 19,000
f(BsBs) (93 79 1)
Bs Bs channel
N ev 94,000 7,000 20,000
105 Bs mesons per 1 fb-1 at Y(5S)
Biggest uncertainty comes from fs systematics.
How to improve it (3 times)?
14
Improved measurement of fs
14
How to measure fs with 5 uncertainty ?
I spent a lot of time thinking about that. It
could be
1. CLEO method, from Bf(Y(5S)-gt Ds X), with
better statistics.
2. Using same-sign lepton-lepton sample, maybe
with z-distance measurement between
profile-lepton vertices
3. J/y vertex xy-distance from profile.
4. Bf(B-gt Dp-), Bf(B-gt D0p-), Bf(B-gt D0p-)
measurements.
5. Number of slow photons from Bs decays.
No one of these methods is perfect
15
New Belle results with 23.6 fb-1
15
First observation of Bs-gt f g and new upper limit
for Bs-gt gg.
Bf (Bs-gtfg)(5.7 1.81.2) 10-5
-1.5-1.1
Jean Wicht
Bf (Bs-gtgg) lt 8.7x10-6 (90 CL)
First measurement of Y(5S) -gt Y(nS) pp-decays
(21.7 fb-1).
16
Is the ?(10860) purely ?(5S)?
16
-gt look for
mm-hh-
U(2S)
ee- -gt U(1S) pp-X
ee- -gt U(2S) pp-X
U(3S)
U(2S)
arXiv0710.2577hep-ex (accepted PRL)
U(1S)
Study motivated by observation of Y(4230) -gt J/Y
pp- signal (analogous?).
U(1S)
17
Is the ?(10860) purely ?(5S)?
17
Y(5S) -gt U(nS) hh-
4 modes seen
Conclusion not pure ?(5S)? Energy scan 12/07 .
18
New Belle results with 23.6 fb-1
18
First observation of Bs-gt f g and new upper limit
for Bs-gt gg.
Bf (Bs-gtfg)(5.7 1.81.2) 10-5
-1.5-1.1
Jean Wicht
Bf (Bs-gtgg) lt 8.7x10-6 (90 CL)
First measurement of Y(5S) -gt Y(nS) pp-decays
(21.7 fb-1).
First measurement of Bs-gt X l - n decay.
19
Motivation, feasibility of Bs lifetime
measurement.
19
PDG 2007 Bf( B0-gtXl-n ) ( 10.33 ? 0.28 )
Semileptonic decays have no hadronic corrections.
Theory predicts about 12. It is not yet
understood by theory. Some recent models predict
better (dis)agreement. Calculation problems?
Exotics? Maybe semilep. Bs decays can shed some
light.
t(B0) gt t(Bs) - 2.9s difference (in contrast
with theory).
Bs and Ds lifetimes can be measured using Ds
vertex, lepton track and beam profile.
K
K-
p
m
Ds
This analysis requires much more work .
z
20
First measurement of Bs-gt Xl -n decay
20
Electron
Muon
DATA
DATA
MC
23.6 fb-1
23.6 fb-1
from Ds,D
from Bs
Electron Bf( Bs-gtXe-n ) ( 10.9 ? 1.0 ? 0.9
)
Muon Bf( Bs-gtXm-n ) ( 9.2 ? 1.0 ? 0.8 )
preliminary
preliminary
Combined fit (electronmuon)
Bf( Bs-gtXl-n ) ( 10.2 ? 0.8 ? 0.9 )
Assuming similar decay widths and
t(Bs)/t(B0)1.00?0.01 (theory exp.diff.2.3s)
it can be compared to PDG 2007 Bf( B0-gtXl-n )
( 10.33 ? 0.28 )
21
New Belle results with 23.6 fb-1
21
First observation of Bs-gt f g and new upper limit
for Bs-gt gg.
Bf (Bs-gtfg)(5.7 1.81.2) 10-5
-1.5-1.1
Jean Wicht
Bf (Bs-gtgg) lt 8.7x10-6 (90 CL)
First measurement of Y(5S) -gt Y(nS) pp-decays
(21.7 fb-1).
First measurement of Bs-gt X l - n decay.
Measurement of Bs-gt Dsp- and Bs-gtDsK- decays.
R. Louvot, T. Aushev, J.Wicht
Bf (Bs-gtDsp-)(3.31 0.310.67) 10-3
-0.30-0.64
Bf (Bs-gtDsp-)(2.2 1.10.5) 10-4
R0.066 ?0.015
-0.9-0.4
22
Why it is interesting?
22
Bf (Bs-gtDsp-)(3.31 0.310.67) 10-3
1.
-0.30-0.64
Bf (B-gtDp-)(2.68 ? 0.13) 10-3
PDG
W-exchange diagram? Difference is not yet
significant.
2. M(Bs)5417.4 ? 0.4 ? 1.0 MeV/c2
PDG
M(Bs)5366.1 ? 0.6 MeV/c2
D(Bs0) 51.3 ? 1.2 MeV/c2
D(B0) 45.78 ? 0.35 MeV/c2
Very unexpected difference
N(BsBs) / N(Bs()Bs()) (90 3.73.9 0.2)
very unexpected
3.
4. Flat B direction angular distribution gt has
to be explained.
23
Belle results expected soon with 23.6 fb-1
23
1. K. Sayeed, A. Schwartz Bs-gt J/y f and Bs-gt
J/y Ks decays.
Important for future CP studies.
2. J.-H. Chen Search for Bs-gt K K- decay.
CP eigenstate, can be used in future for DGs/Gs
measurement.
Analysis started
1. S. Esen Measurement Bs-gt Ds() Ds-()
Mostly CP eigenstates, important for indirect
DGs/Gs measurement.
24
DGs/Gs measurement from Bf (Bs -gt Ds() Ds-())
24
MBs (MH ML)/ 2 Gs (GH GL)/ 2
Dms MH ML DG GL- GH gt0 in SM
( )
( )
d
Bs
Bs

i
- Schrodinger equation
i
( M / 2 G )
d t
Bs
Bs
Matrices M and G are t-dependent, Hermitian 2x2
matrices
Assuming CPT M11 M22 G11 G22
BH,L(t) gt exp( - ( i MH,LGH,L/ 2)t )
BH,Lgt
SM bsarg(-Vts Vtb/ Vcs/ Vcb) O(l2) - no
CP-violation in mixing
BSM fs arg (- M12/ G12) 2qs fs
DGs 2 G12 cos 2qs
25
DGs/Gs measurement from Bf (Bs -gt Ds() Ds-())
25
(first proposed by Y. Grossman)
DGs 2 G12 cos fs
DGsSM DGCPs 2 G12
Since DGCPs is unaffected by NP, NP effects will
decrease DGs.
DGCPs S G(CP) S G(CP )
Bs-gtDs() Ds() - decays have CP-even final
states with largest BFs of (1-3) each,
saturating DGs/Gs .
DGCPs
Bf(Bs-gtDs() Ds() - )


Gs
1- Bf(Bs-gtDs() Ds() - ) / 2
To prove this formula experimentally a)
Contribution of Bs -gt Ds() Ds-() np is small
b) Most of Bs -gt Ds Ds- and Bs -gt Ds Ds-
states are CP- even.
Assuming corrections are small (5-7), Bf
measurement will provide information about DGCPs
or G12.
26
DGs/Gs measurement from Bf (Bs -gt Ds() Ds-())
26
Expected with 25 fb-1 at Y(5S)
Y(5S), 1.86 fb-1
N 107 x 2x10-4 x 10-2 5 ev
Eff(Bs-gtDs Ds- ) 2x10-4
N 107 x 10-4 x 2x10-2 55 ev
Eff(Bs-gtDs Ds- ) 1x10-4
Bs-gt Ds Ds-
N 107 x 5x10-5 x 3x10-2 4 ev
Eff(Bs-gtDs Ds- ) 5x10-5
Bs-gt Ds Ds-
Bs-gt Ds Ds-
gtAccuracy of Bf (Bs-gtDs() Ds()- ) has to be
25.
Ds -gt fp , K0 K, Ks K
DGCPs
Bf(Bs-gtDs() Ds() - )
should be compared with direct DGs/Gs
measurement to test SM.
lt


Gs
1- Bf(Bs-gtDs() Ds() - ) / 2
DGs/Gs lifetime difference can be measured
directly with high accuracy at Y(5S) and also at
Tevatron and LHC experiments.
27
Further physics program with 23 fb-1
27
1. Bs -gt Ds r- , Bs -gt Ds a1- ,
Bs -gt Ds p- , Bs -gt Ds r- , Bs -gt Ds a1- .
BFs should be compared with B0 partners to test
SU(3).
2. Bs -gt J/y h , J/y h , J/y w, J/y f0(980) ,
,Bs-gt J/y K K-.
What is fraction of ss component in different
mesons?
Quark model y(h)(uudd-ss)/ 3 y(h
)(uudd2ss)/ 6
B(Bs0-gtJ/y h) 1/3 B(Bs0-gtJ/y f)
B(Bs0-gtJ/y h ) 2/3 B(Bs0-gtJ/y f)
Mixed channels? Enhanced branching fractions?
28
Further physics program with 23 fb-1
28
3. Bs -gt DsJ p- (4 states).
Interesting physics issues, critical test of DsJ
nature. Inclusive DsJ production study?
4. Bs -gt D0 K0().
Statistically significant signals are expected
with BFs predicted at C-K.Chua,W-S.Hou,
hep-ph/0712.1882.
Color-suppressed
Bf(Bs-gtD0K0) 8x10- 4 gt 20 signal events
should be seen with 23.6 fb-1 at Y(5S).
29
Color-suppressed Bs-gt D0 K0 decay
29
Color-suppressed
Color-suppressed
FSI
Bf (B0-gtD0p0)
(2.91 0.28) x10- 4
0.1


Bf (B0-gtDp-)
(3.4 0.9) x10- 3
Which diagram, color-suppressed or FSI, is
dominant in B0-gtD0p0 decay ? Decay mode
Bs-gtD0K()0 has no FSI diagram. If the ratio
Bf(Bs-gtD0K0)/Bf(Bs-gtDsp-) 0.1, then
color-suppressed diagram dominates. If the ratio
is significantly smaller, then FSI diagram
dominates.
30
Further physics program with 23 fb-1
30
5. Bs -gt Ds l- n , Bs -gt Ds l- n (Bs-gtK
l- n?).
Important SU(3) test. CDF obtained large DsJ
semileptonic BF (?).
6. Bs decays with baryons (with L0 baryons).
Largest B0 baryonic Bfs are 10-3. Is it
similar in Bs decays?
7. Bs lifetime measurement.
Different samples can be used fully
reconstructed events, CP-fixed modes, two lepton
events, Ds lep events .
Good accuracy is expected (5-10). Important
measurement.
31
Feasibility of Bs lifetime measurement with
same-sign leptons
31
Lifetime can be measured using two fast same
sign lepton tracks and beam profile. To remove
secondary D meson semileptonic decays P(l )gt1.4
GeV.
Y(5S) Bs(l ) Bs(l ) / Bs(l ) Bs(l -) 100
Y(4S) B(l ) B(l ) / B(l ) B(l - ) 10
m
m
Beam profile
Dz bgc Dt
Bs
Y(5S)
Bs
Z beam 3 mm Dz 0.1- 0.2 mm.
32
32
Comparison with Fermilab Bs studies.
There are several topics, where Y(5) running has
advantages comparing with CDF and D0 1) Model
independent branching fraction measurements. 2)
Measurement of decay modes with g, p0 and h in
final state (Dsr-). 3) No trigger problems for
multiparticle final states (like Ds Ds-). 4)
Inclusive branching fraction measurements
(semileptonic Bs). 5) Partial reconstruction ( Bf
(Ds l- n) using missing- mass method).
There are also disadvantages 1) We have to
choose between running at Y(4S) or Y(5S). 2)
Number of Bs is smaller than in Fermilab
experiments. 3) Vertex resolution is not good
enough to measure Bs mixing (???).
33
Future physics program at Y(5S)
33
Realistic value of 200 fb-1
Optimistic value of 2000 fb-1
Only big deals
1. DGs/Gs measurement
Decay modes Ds()Ds(), KK-, ff, fg, J/y h(f)
500 CP-fixed events with 200fb-1 gt 5-10
accuracy in Gs.
Measurement of Bs-gt gg decay
2.
It also requires about 1000fb-1 to measure.
3. Bs mixing measurement
34
Bs mixing measurement
34
It is often postulated, that Bs mixing cannot me
measured at the Y(5S). Have anybody checked it?
Is it correct or not?
Can we measure Bs mixing? Lets check it.
Distance between max and min of oscillation
function Dz p Dms bgc 22.5mm with bg0.425
Can we increase bg at Y(5S) runs by 50? Probably
yes.
Then we need to get single vertex resolution of
20 mm.
Is is planned resolution for fast (00 dip angle)
tracks (next slide).
gt with high statistics we can select high vertex
resolution events.
Yes, we can.
35
Impact Parameter resolution
T.Kawasaki, Atami BNM2008 Jan 2008
Calculated by TRACKERR
r-f direction
z direction
cm
cm
0.02
0.03
LoI 04 sBelle SVD2(now)
For p- 0.2GeV 0.5GeV 1.0GeV 2.0GeV
0.01
20mm
0
1.4
sinq
Occupancy effects. Degradation of intrinsic
resolution is included. Efficiency loss
is NOT included
Beampipe radius is important Competitive
performance as the current SVD
36
What else can be done at Super B Factory?
36
PDG (Z-gtbb, pp at S1/21.8TeV) b hadron
fraction() B , B0 39.8 1.0 Bs
10.4 1.4 b baryons 9.9 1.7
Rates at ee- continuum should be similar, baryon
production is large.
M(Lb) (5624 9) MeV/c2
M(Lb)x2 (11248 18) MeV/c2 gt 6.3 up from
Y(4S) CME.
Can Super B factory CM energy range be increased ?
M(Bc) (6286 5) MeV/c2
_
_
_
_
ee- Y(6S,7S) BsBs, LbLb, BcBc, Xb Xb ?
37
Conclusions
37
Bs decays with branching fractions down to 10-6
can be measured with statistics of 100 fb-1 at
ee- colliders running at Y(5S).
Many important SM tests can be done with
statistics of the order of 1000 fb-1.
Bs studies at e e- colliders running at Y(5S)
have some advantages comparing with hadron-hadron
colliders. These colliders are in some sense
complementary.
It is important to have more flexibility in beam
energies.
38
Background slides
39
Belle Detector
Cherenkov detector n1.0151.030
SC solenoid 1.5T
3.5GeV e
EM calorimeter (CsI(Tl))
TOF counter
8GeV e-
Central drift chamber He(50)C2H6(50)
m / KL detector
Si vertex detector
40
dz resolution
T.Kawasaki, Atami BNM2008 Jan 2008
dz
dz resolutoin SuperB SVD3mod SVD3 For p
0.2GeV 0.5GeV 1.0GeV 2.0GeV
Write a Comment
User Comments (0)
About PowerShow.com