A. Drutskoy

1
A. Drutskoy University of Cincinnati
Bs physics at Y(5S) in Belle experiment
SLAC Experimental Seminar
January 17, 2006, SLAC.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Outline
Introduction.
Data taking.
Number of bb events at Y(5S) dataset.
Inclusive production of J/Y, D0 and Ds at Y(5S).
Exclusive decays Bs-gt J/Y f (/h) and Bs-gt Ds()
p- (/r-).
Search for rare Bs decays.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Introduction
Asymmetric energy ee- colliders (B Factories)
running at Y(4S) Belle and BaBar
1985 CESR (CLEO,CUSB) 116 pb-1 at Y(5S)
2003 CESR (CLEO III) 0.42 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
_
_
_
B0 s b , B0 s b
s
s
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Masses, widths, lifetimes, CM momenta
Particle Mass, MeV/c2 Width, MeV/c2 DM, MeV/c2 ct, mm Pcm(BB), MeV/c
Y(4S) 10580.0 ? 3.5 20 ? 2 ? 4
Y(5S) 10865 ? 8 110 ? 13
B 5279.0 ? 0.5 502 1282
B0 5279.4 ? 0.5 462 1281
B 5325.0 ? 0.6 45.8 ? 0.4 1075
Bs 5365.5 ? 1.3 438 851
Bs 5416.6 ? 3.5 51 ? 4 415
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Electron and positron beam energies have to be
increased by 2.7 (same Lorentz boost bg
0.425) to move from Y(4S) to Y(5S).
No modifications are required for Belle
detector, trigger system or software to
move from Y(4S) to Y(5S).
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Engineering run at Y(5S)
3 days of engineering run at Y(5S) June 21
June 23. Plan for 3 day engineering runs 1.
Energy scan five points with 30 pb-1 at each
point 10825, 10845, 10865, 10885 and 10905
MeV. 2. Data taking at Y(5S) peak to collect
integral lumi 2 fb-1 . Results Y(5S) peak
position ECM10869 MeV was chosen from energy
scan. Integrated luminosity of 1.86 fb-1 (ECL
lumi) was taken !!! Maximum luminosity 13.9
/nb/sec, almost 100 of Y(4S) specific luminosity
(taking into account smaller currents). Belle
can take 1 fb-1 per day at Y(5S) or even
more. Very smooth running, all goals are reached.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Hadronic event classification
hadronic events at U(5S)
u,d,s,c continuum
U(5S) events
b continuum
bb events
B0, B events
Bs events
Bs Bs
Bs Bs
Bs Bs channel
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Number of Bs in dataset
To calculate any exclusive branching fraction we
must know the full number of Bs Bs events. To
calculate any inclusive branching fraction we
must know the full number of Bs mesons.
To obtain the full number of initial Bs Bs
events in our data sample we should go through
steps 1. Obtain the number of hadronic events
in Y(5S) dataset. 2. Subtract u,d,s,c continuum
using continuum data below Y(4S) with luminosity
scale factor. 3. Calculate the ratio
N(Bs()Bs()) / N(bb) using inclusive Ds and D0
spectra. 4. Calculate the ratio N(BsBs)/
N(Bs()Bs()) using reconstructed exclusive
events.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Number of bb events.
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
Lumi 3.670 0.001 (stat) fb-1
2
s 1/Ecm
(1.857/3.67)(10.5189/10.869)2 0.4740 0.0019
e5S/ econt 1.007 0.003
Nbb(5S)
561,000 3,000 29,000
R s(hadrons) / s(mm)
Nbb(5S) / fb-1 302,000 15,000
CLEO 0.42 fb-1 Nbb(5S)/ fb-1 310,000
52,000
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Luminosity ratio L (5S) / L (continuum).
L (5S) / L (cont) 0.4740 0.0019
We obtained luminosity ratio
Luminosity ratio can be checked using the ratio
of normalized momentum distributions of fastest
charged track, fastest K0 and D0 mesons.
Using MC simulation CLEO obtained (0.6 1.1)
correction for new channels opening. That
correction was applied to these numbers.
0.477 0.005
0.471 0.005
0.471 0.005
gt Good agreement within errors with energy
corrected luminosity ratio.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Inclusive analyses selections
Particle ID p/K standard ID(K/p) J/Y -gt m m-
Standard Muon ID D0 -gt K p- no cuts Ds -gt
fp M(f) M(KK-) lt 12 MeV/c2
3s cos(qheli) (Ds) gt 0.25 for fp No
continuum suppression cuts.
Ratio of Bs() Bs() pair number to all bb pair
number fs N(Bs() Bs()) / N(bb) can be
obtained from
Bf (Y(5S) -gt Ds X) / 2 fs Bf (Bs -gt Ds X)
(1- fs) Bf (B -gt Ds X)
x
x
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Inclusive analysis Y(5S) -gt Ds X
Theory
hep- ex/0508047 CLEO
Y(5S)
P/Pmaxlt 1
Bf (Bs -gt Ds X) (92 11)
PDG
Bf (Ds-gt f p)(3.6 0.9)
Bf(Ds-gt f p)(4.8 0.6)
Babar
Ds-gt f p
Sum Bf(Ds-gt f p) (4.4 0.5)
3775 100 ev
CLEO
Bf (B -gt Ds X) ( 9.0 0.3 1.4 )
Babar
Bf (B -gt Ds X) ( 8.94 0.16 1.12 )
After continuum subtraction and efficiency
correction
Bf (Y(5S) -gt Ds X) 2 (22.6 1.2 2.8)
CLEO measured Bf (Y(5S) -gt Ds X) / 2 (22.35
2.1 4.95)
gt
fs (16.4 1.4 4.1 )
Syst. err. dominates by Bf(Ds-gtfp)
Using Ds mesons CLEO measured fs (16.0 2.6
5.8 )
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Inclusive analysis Y(5S) -gt D0 X
Theory
hep- ex/0508047 CLEO
Y(5S)
Bf (Bs -gt D0 X) (8 7)
PDG
D0 -gt K- p
Bf (B -gt D0 X) (63.7 3.0)
55009 510 ev
Bf (D0 -gt K- p) (3.81 0.09 )
P/Pmaxlt 1
After continuum subtraction and efficiency
correction
Bf (Y(5S) -gt D0 X) 2 (53.3 2.0 2.9)
Then we obtain ratio fs N(Bs() Bs()) / N(bb)

fs (18.7 3.6 6.7 )
Syst. error dominates by N(bb).
Using Ds mesons CLEO measured fs (16.0 2.6
5.8 )
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Inclusive analysis Y(5S) -gt J/Y X
Theory
Bf(Bs-gt J/Y X)
P/Pmaxlt0.5
Y(5S)
1.00 0.10
Bf(B -gt J/Y X)
44628 ev
mm-
PDG
Bf (B -gt J/Y X) (1.094 0.032)
Bf (J/Y -gt m m- ) (5.88 0.10 )
After continuum subtraction and efficiency
correction
Bf (Y(5S) -gt J/Y X) 2 (1.068 0.086
0.057)
Good agreement with expectations gt bb number is
correct
Assuming approximately 17 Bs()Bs() production
over bb
Bf ( Bs -gt J/Y X) ( 0.94 0.51 0.37 )
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Exclusive analysis signature of fully
reconstructed Bs decays
BsBs , BsBs , BsBs
Mbc vs DE
Mbc Ebeam2 PB2
e e- -gt Y(5S) -gt BB, BB, BB, BsBs, BsBs,
BsBs
where B -gt B g and Bs -gt Bs g
Detailed MC event simulation and reconstruction
with Belle detector was performed. Figures are
shown for decay mode Bs -gt Ds- p with Ds- -gt f
p- .
Bs signal can be well separated for BsBs, BsBs
and Bs Bs final states.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Exclusive analyses selections
Particle ID K/p standard ID(K/p) standard
lepton ID Masses p0 gt gg 3s KS gt p
p- 3s K0 gt K p- h gt gg 2.5s r
gt p p0 , P(g) gt150 MeV/c f gt KK-
3s 30 lt M(mm-) M(J/y) lt 30 MeV/c2
3s 100 lt M(ee-) M(J/y) lt 30 MeV/c2 Ds -gt
fp , K0 K, Ks K 3s Ds -gt Ds g
M(Dsg)- M(Ds), 2s , P(g)gt50
MeV/c Continuum suppression Angle between Bs
thrusts cosq lt 0.8 for Ds() p- cosq lt
0.9 for J/Y cosq lt 0.7 for Ds() r-
cosq lt 0.6 for K0 K modes Fox2lt0.3 for
Ds() p-/ r- Fox2lt0.4 for J/y modes
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Exclusive Bs -gt Ds() p- decays
Bs -gt Ds p-
Bs -gt Ds p-
BsBs , BsBs , BsBs
MC
9 events in Bs Bs
4 events in Bs Bs
Ds -gt f p , Ds -gt K0 K, Ds -gt Ks K
Clear signal at Bs Bs channel no signals in
Bs Bs and BsBs channels.
Taking full number of Bs from inclusive analysis
Bf(Bs -gt Ds p- ) (0.65 0.21 0.19)
CDF measured Bf ratio, taking Bf(B0-gtDp-) from
PDG (0.40 0.06 0.13)
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Exclusive Bs -gt Ds() r- and Bs -gt J/y f/h
decays
Bs -gt Ds() r-
Bs -gt J/y f/h
7 events in Bs Bs
3 events in Bs Bs
Bs -gt J/y h(gg)
Bs -gt J/y f,
Ds-gtf p ,Ds-gtK0 K,Ds-gtKsK
Clear signal at Bs Bs channel signals in Bs
Bs and BsBs channels are not seen.
Bs Bs channel dominance was also observed by
CLEO (next slide).
We can combine all shown channels to obtain
quantitative Bs() parameters.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Exclusive Bs Signals at the ?(5S)
Nsignal 4, Nbkg ? 0.1
Nsignal 8, Nbkg ? 1
?(5S) decay to Bs()Bs() is dominated by the
BsBs mode!
H. Vogel, CLEO, FPCP 2004 (obsolete), Korea,
exclusive Bs decays
- 13 -
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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DE distributions, sum of all Bs decay modes
5.408lt MBClt5.429 GeV/c2
5.384lt MBClt5.405GeV/c2
5.36lt MBClt5.38GeV/c2
Bs Bs
Bs Bs
Bs Bs
Nev20.0 4.8
6.7 s
Small signal, Nev 1.3 2.0 (6 96)
Decay U(5S) -gt Bs Bs , with Bs -gt Bs g.
Potential models predict Bs Bs dominance over
BsBs and BsBs channels, but not so strong.
DE peak Ecm(accel.)/2 Ecm(real)/2 E(g)
DE peak 47.6 2.6 MeV
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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MBC distribution, sum of all Bs decay modes
- 0.08ltDElt- 0.02 MeV
- 0.08ltDElt- 0.02 MeV
Bs Bs
Bs Bs
Mbc (EB DEpeak)2 PB2
Mbc EB2 PB2
M (Bs) 5370 1 3 MeV/c2
Ecm 10869 MeV EB Ecm/2
PDG M (Bs) 5369.6 2.4 MeV/c2
M (Bs) 5418 1 (acc. err) MeV/c2
CDF M (Bs) 5366.0 0.8 MeV/c2
Photon momentum is neglected gt does not change
Bs mass position, only smearing.
Photon energy smearing does not change Bs mass
position
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Number of Bs in dataset
Lumi 1.857 fb-1
hadronic events at Y(5S)
bb continuum included
bb events
N ev 561,000 3,000 29,000
fs (16.4 1.4 4.1 )
Bs events
N ev 92,000 8,000 23,000
f(BsBs) (94 69)
Bs Bs channel
N ev 86,500 7,500 22,500
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Exclusive Bs -gt K K- and Bs -gt f g decays
Bs -gt f g
Bs -gt K K-
MC
Fox2 lt 0.3,
Fox2 lt 0.4,
cos q lt 0.5
cos q lt 0.8
K- tight ID(K/p),
Bgr. 0.15 ev. Est. sign. 0.4 ev.
Bgr. 0.14 ev. Est. sign. 0.7 ev.
Partner of B -gt K g penguin decay
Partner of B -gt K p- penguin decay
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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CDF Bs-gt h h- decays
Unbinned likelihood fit.
fs Bf( Bs -gt K K-)
0.50 0.08 0.07
fd Bf( B0 -gt K p-)
fs Bf( Bs -gt K p-)
lt 0.11 (90CL)
fd Bf( B0 -gt K p-)
Bf( Bs -gt p p-)
lt 0.10 (90CL)
Bf( Bs -gt K K-)
No absolute branching fractions. Statistical
separation of final states.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Exclusive Bs -gt Ds() Ds()- decays
Bs-gt Ds Ds-
Bf(Bs-gtDs Ds- ) lt 7.1 at 90 CL
Bs-gt Ds Ds-
Bf(Bs-gtDs Ds- ) lt 12.7 at 90 CL
Bs-gt Ds Ds-
Bs-gt Ds Ds-
Bf(Bs-gtDs Ds- ) lt 27.3 at 90 CL
Expected (2 fb-1) 0.5 events in each mode.
Bf (Bs-gtDs() Ds()- ) (12 5 )
Expected with 30 fb-1
Ds -gt fp , K0 K, Ks K
Fox2 lt 0.4
Bs-gtDs() Ds() - decays are CP- even
states with large BFs, leading to large DGs/Gs
cos q lt 0.8
Angle between B thrusts
DGs
Bf(Bs-gtDs() Ds() - )
should be compared with direct measurement to
test SM.

lt

Gs
1- Bf(Bs-gtDs() Ds() - ) / 2
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Exclusive Bs -gt g g decay
Bs -gt g g
MC
DE
Natural mode to search for BSM effects, many
theoretical papers devoted to this decay. In SM
Bf(Bs-gt gg ) (0.5 -1.0) x 10-6 BSM can
increase Bf up to two orders
MC
Fox2 lt 0.5
cos q lt 0.8
90 CL UL with 1.86 fb-1 Bf(Bs -gt gg ) lt 0.56
x 10- 4.
Better than PDG limit lt 1.48 x 10- 4
Many conventional BSM models can be better
constrained by B -gt K g and B-gts g g
processes, however not all. In some BSM models Bs
-gtgg provides the best limit, in particular in
4-generation model (VTs) and R- parity violation
SUSY ( x M(gg)).
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Signals with 50 fb-1
Bs -gt Ds() Ds()- - CP eigenstate
Bs -gt g g - intrinsic penguin
Bs -gt K K- - penguin
Bs -gt f g - radiative penguin
Bs -gt DsJ p - tree with DsJ
Bs -gt Ds K- - Cabibbo suppressed
Bs -gt Dsl - n - exclusive leptonic
Bs -gt D0 KS0 - color suppressed
Bs lifetime
Bs semileptonic
It seems, very strong physics program can be
performed with 50 fb-1
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Conclusions
Inclusive production branching fractions of J/Y,
D0 and Ds mesons are measured at Y(5S). Ratio of
Bs meson production over all bb-events is
measured fs (16.4 1.4 4.1 )
Significant exclusive Bs signals are observed in
Y(5S) -gt Bs Bs channel. Combining all studied
decay modes, mass of Bs meson was
measured M(Bs) 5418 1 (acc. err) MeV/c2,
and mass of Bs was measured M (Bs) 5370 1
3 MeV/c2. Obtained Bs mass is in agreement with
recent CDF measurement M (Bs) 5366.0 0.8
MeV/c2.
Good agreement with published CLEO results is
obtained in both inclusive and exclusive
analyses. Our Y(5S) dataset is 4.4 times
larger than CLEO dataset, providing better
accuracy.
Rare Bs decays are searched for at Y(5S) for the
first time.
Many new interesting results can be obtained with
50 fb-1. Significant signals are expected in many
Bs decays with 50 fb-1 (maybe 30
fb-1) Engineering runs demonstrated, that
background level is not large for studied decay
modes.
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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Background slides
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy
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CDF Bs-gt Ds-p decays
Results with 119 pb-1
fs Bf( Bs -gt Ds- p)
0.35 0.05 0.04 0.09
fd Bf( B0 -gt D- p)
From PDG fs / fd 0.2700.028 , fs is rate of
b quark -gt Bs
Uncertainty of absolute branching fraction
measurement dominates already by 10 uncertainty
of fs/fd.
Bf( Bs -gt Ds- p)
1.4 0.2(stat) 0.2(syst) 0.4(BF) 0.2(PR)
Bf( B0 -gt D- p)
Bs physics at Y(5S), SLAC seminar, Jan 17,
2006, A. Drutskoy