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B physics at U (5S). A. Drutskoy, University of Cincinnati. ITEP Meeting. on the Future of Heavy Flavor Physics. July 24 – 26, 2006, Moscow, Russia. ITEP Meeting B physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy. Outline.

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A drutskoy university of cincinnati

B physics at U(5S)

A. Drutskoy,

University of Cincinnati

ITEP Meeting

on the Future of Heavy Flavor Physics

July 24 – 26, 2006, Moscow, Russia.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Outline

Introduction.

Recent Belle measurements at the Y(5S).

Future searches for BSM using Bs decays at Y(5S).

Conclusion.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

CLEO

PRL 54, 381 (1985)

CLEO

PRL 54, 381 (1985)

(5S)

(5S)

Introduction

(4S)

Asymmetric energy e+e- 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)

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- ->Y(4S) -> BB, where B is B+ or B0 meson

_

_

_

_

_

_

_

_

e+ e- -> Y(5S) -> BB,B*B, B*B*, BBp, BBpp, BsBs, Bs*Bs, Bs*Bs*

where B* -> B gandBs* -> Bsg

G(Y(5S)) = 110  13MeV/c2 (PDG)

M(Y(5S)) = 10865  8 MeV/c2 (PDG)

Bs rate is ~10-20% => high lumi e+e- collider at the Y(5S) -> Bs factory.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

First Y(5S) runs at the KEKB e+e- 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 GeVe-

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 can be taken at Y(4S) and Y(5S).

Very smooth running

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Belle integrated luminosity at Y(4S)

  • Integrated luminosity reached 600 fb-1 on May 31st .

~630fb-1

Belle

May-31st

Babar

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Inclusive analyses : Y(5S) -> Ds X , Y(5S) -> D0X

points:5S

hist: cont

points:5S

hist: cont

Y(5S)

P/Pmax<0.5

Ds-> fp+

Ds-> fp+

3775 ± 100 ev

D0 -> K-p+

After continuum subtraction and efficiency correction:

L = 1.86 fb-1

Bf (Y(5S) -> Ds X) 2 = (23.6 ± 1.2 ± 3.6) %

Nbb(5S) =

561,000 ± 3,000 ±29,000 events

Bf (Y(5S) -> D0 X) 2 = (53.8 ± 2.0 ± 3.4) %

fs = N(Bs(*) Bs(*)) / N(bb)

=>

= (18.0 ± 1.3 ± 3.2 )%

N(Bs) / fb-1 = 108,000 ± 21,000 events

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Signature of fully reconstructed exclusive Bs decays

BsBs , Bs*Bs, Bs*Bs*

MC

Zoom

Mbc vs DE

Mbc vs DE

whereBs* -> Bsg

e+ e- -> Y(5S) -> BsBs, Bs*Bs,Bs*Bs*,

Reconstruction: Bsenergy and momentum, photonfrom Bs* is not reconstructed.

Mbc = E*beam2 – P*B2 ,

DE = E*B – E*beam

Two variables calculated:

Figures (MC simulation) are shown for the decay mode Bs -> Ds-p+ with Ds- -> fp- .

The signals for BsBs, Bs*Bs and Bs* Bs* can be separated well.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Exclusive Bs -> Ds(*)+p-/r- and Bs-> J/y f/h decays

Data at Y(5S), 1.86 fb-1

Bs -> Ds+p-

Bs -> J/y f/h

Bs -> Ds*+p-

Bs -> Ds(*)+r-

9 evnts in Bs* Bs*

4 evnts in Bs* Bs*

7 evnts in Bs* Bs*

3 evnts in Bs* Bs*

N(Bs*Bs*) / N(Bs(*)Bs(*))= (94± 69)%

5.408<MBC<5.429GeV/c2

Potential models predict Bs* Bs* dominance over Bs*Bs and BsBs channels, but not so strong.

Bs* Bs*

Nev=20.0 ± 4.8

Conclusions:

1. Belle can take ~30 fb-1 per month ( x2 soon).

2. Number of produced Bs at Y(5S) is ~105/fb-1.

3. Bs*Bs* channel dominates over all Bs(*)Bs(*).

4. Backgrnds in exclusive modes are not large.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

DGs/Gs measurement from Bf (Bs -> Ds+(*) Ds-(*))

MBs = (MH + ML)/ 2 Gs = (GH + GL)/ 2

Dms = MH – MLDG = GL- GH>0 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 = M22G11 = G22

| BH,L(t) > = exp( - ( iMH,L+GH,L/ 2)t ) | BH,L>

SM: bs=arg(-Vts Vtb*/ Vcs/ Vcb*) =O(l2) - no CP-violation in mixing

BSM : fs = arg (- M12/ G12) 2qs = fsDGs = 2 | G12| cos 2qs

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

DGs/Gs measurement from Bf (Bs -> Ds+(*) Ds-(*))

DGs = 2 | G12| cos fs

DGsSM = DGCPs = 2 | G12|

Since DGCPs is unaffected by NP, NP effects will decrease DGs.

DGCPs = S G(CP=+) – SG(CP= –)

Bs->Ds(*) + Ds(*) - decays have CP- even final states with

largest BF’s of ~ (1-3)% each, saturating DGs/Gs .

DGCPs

Bf(Bs->Ds(*) + Ds(*) - )

~

~

Gs

1- Bf(Bs->Ds(*) + Ds(*) - ) / 2

To prove this formula experimentally : a) Contribution of

Bs -> Ds+(*) Ds-(*) np is small b) Most of Bs -> Ds+ Ds- *

and Bs -> Ds+* Ds- * states are CP- even.

Assuming corrections are small (~5-7%), Bf measurement will

provide information about DGCPs or |G12|.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

DGs/Gs measurement from Bf (Bs -> Ds+(*) Ds-(*))

Expected with 100 fb-1 at Y(5S):

Y(5S), 1.86 fb-1

N ~ 107 x 2x10-4 x 10-2~ 20 ev

Eff(Bs->Ds+ Ds-) ~ 2x10-4

N ~ 107 x 10-4 x 2x10-2~ 20+20 ev

Eff(Bs->Ds*+ Ds-) ~1x10-4

N ~ 107 x 5x10-5 x 3x10-2~ 15 ev

Bs-> Ds+ Ds-

Eff(Bs->Ds*+ Ds*-) ~5x10-5

Bs-> Ds*+ Ds-

Bs-> Ds*+ Ds*-

=>Accuracy ofBf (Bs->Ds(*)+Ds(*)-) has to be ~15%.

Ds+ -> fp+ , K*0 K+, Ks K+

DGCPs

Bf(Bs->Ds(*) + Ds(*) - )

should be compared with direct

DGs/Gs measurement to test SM.

~

<=

~

Gs

1- Bf(Bs->Ds(*) + Ds(*) - ) / 2

DGs/Gs lifetime difference can be measured directly with high

accuracy at Y(5S) and also at Tevatron and LHC experiments.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Semileptonic Bs decays

At the Y(5S) we can measure precisely semileptonic decays:

Bf (Bs->X+l-n)

Accuracy is expected to be

~5% with 100 fb-1 at Y(5S)

Bf (Bs->Ds+l-n)

Bf (Bs->Ds*+l-n)

Difficult to measure in hadron-hadron colliders.

These Bf’s have to be compared with corresponding B meson

Bf’s. This comparison provides important test of SU(3)

symmetry and quark-qluon duality.

Motivations:

1. t(B0) > t(Bs) - 2.9s difference (in contrast with theory).

2. Measured B0 semileptonic Bf is a bit lower than theoretical

prediction.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Exclusive Bs -> g gdecay

Bs -> g g

1.86 fb-1

MC

Natural mode to search for BSM

effects, many theoretical papers

devoted to this decay.

PDG limit : Bf (Bs -> gg ) < 1.48 x 10-4

90% CL UL with 1.86 fb-1 :Bf (Bs -> gg ) < 0.56 x 10- 4.

Expected UL with 100 fb-1 :Bf (Bs -> gg ) < 1. x 10- 6.

SM:Bf (Bs -> gg ) = (0.5-1.0) x 10- 6.

BSM can increase Bf up to two orders of magnitude.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Exclusive Bs -> g gdecay

Many “conventional” BSM models can be better constrained by B -> K* g and

B->s g g processes, however not all. In some BSM models Bs -> gg provides the best

limit, in particular in 4-generation model (VTs) and R- parity violating SUSY ( x M(gg)).

VTb

hep-ph/0302177 (Huang et al) : limits on four-generation

matrix elements VTb and VTs were obtained from B decays.

Bf(Bs->gg) can increase up to one order of magnitude

under specific conditions. Decay B-> gg is not affected.

VTs

hep-ph/0404152 (Gernintern et al): within

R-parity violation SUSY, diagram with

sneutrino will increase Bf(Bs->gg) up to

one order of magnitude.

b

_

t

g

n

_

s

g

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Exclusive Bs -> K+ K-, Bs -> K-p+ and Bs->f g decays

Direct CP-violation => non-zero charge asymmetry parameter

A = (Bf (+) – Bf (-) ) / (Bf (+) – Bf (-) ).

Expected number of events with 100 fb-1:

Bs -> K+ K- : ~40 events ; Bs -> K-p+ : ~6 events.

Larger statistics is required to observe direct CP-violation

on the level of 10%.

New Physics can contribute in penguin decay loops.

Bs ->f g

Estimated number of events with 100 fb-1 : ~20 ev.

Partner of B -> K* g penguin decay .

Bf’s have to be compared.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Conclusions

Bs decays with branching fractions down to 10-6 can be studied with

statistics of ~100 fb-1 at e+e- colliders running at Y(5S) .

Many important SM tests can be done with statistics of the order

of (100-500) fb-1.

Bs studiesat e+ e- colliders running atY(5S) have many advantages

comparing with hadron-hadron colliders: high efficiency of photon

reconstruction; 100% trigger efficiency; good K/p PID.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Background slides

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

CLEO

PRL 54, 381 (1985)

(5S)

Hadronic event classification

hadronic events at U(5S)

u,d,s,c continuum

U(5S) events

b continuum

N(bb events) = N(hadr, 5S) - N(udsc, 5S)

bb events

B0, B+ events

Bs events

fs = N(Bs(*) Bs(*)) / N(bb)

Bs* Bs* channel

Bs* Bs

Bs Bs

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Number of bb events, number of Bs events

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

=> 5% uncertainty ( from luminosity ratio)

How to determine fs =N(Bs(*) Bs(*)) / N(bb)?

bb at Y(5S)

_

_

B B

Bs Bs

= fs + (1-fs)

Bf (Y(5S) -> Ds X) / 2

Bf (Bs -> Ds X)

Bf (B -> Ds X)

x

x

1. Bf (Bs -> Ds X) can be predicted theoretically, tree diagrams, large.

2. Bf (B -> Ds X) is well measured at the Y(4S).

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

Feasibility of Bs lifetime measurement with same sign leptons

Lifetime can be measured using two fast same sign lepton

tracks and beam profile. To remove secondary D meson

semileptonic decays: P(l)>1.4 GeV.

Y(5S) : Bs(l +) Bs(l +) / Bs(l +) Bs(l -) = 100%

Y(5S) : 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.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


A drutskoy university of cincinnati

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 (Ds+r-).

3) Measurement of 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.

Running at Y(5S) is a new tool to study Bs physics. First Belle

results are very promising. Collider exists => relatively low price.

ITEP MeetingB physics at Y(5S) , July 24 - 25, 2006 , Moscow, Russia A. Drutskoy


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