CIPANP2003 K. Honscheid Ohio State The Future of Flavor Physics at Hadron Colliders CIPANP 2003 K....

CIPANP2003K. HonscheidOhio State

The Future of Flavor Physicsat Hadron Colliders

CIPANP 2003K. Honscheid

Ohio State University


B Physics Today

CKM Picture okay

CP Violation observed

No conflict with SM

Vud Vus Vub

VCKM = Vcd Vcs Vcb

Vtd Vts Vtb

sin(2) = 0.734 +/- 0.054


Surprising B Physics

Year

Item Theory Prediction ~Value

# B’s

1983 bToo small to be observed ~ < 0.1ps 1 ps 2x104

1987 Bo-Bo mixing

Too small to see (~ < 1%) as mtop is believed to be ~30 GeV

20% 2x105

2001 sin(2) No direct prediction, but consistent with other measurements

3/4 107

>1011 b hadrons

(including Bs)


B Physics at Hadron Colliders

Energy 2 TeV 14 TeVb cross section ~100 b ~500 b

c cross section ~1000 b ~3500 bb fraction 2x10-3 6x10-3

Inst. Luminosity 2x1032 >2x1032

Bunch spacing 132 ns (396 ns) 25 nsInt./crossing <2> (<6>) <1>Luminous region 30 cm 5.3 cm

Tevatron LHC

Large cross sectionsTriggering is an issueAll b-hadrons produced (B, Bs, Bc, b-baryons)


Detector Requirements

From F. Teubert

•Vertex, decay distance•Momentum•PID•Neutrals (, 0)


CDF and D0

CDF pioneered B physics at hadron collider. New for Run II

TOF (Particle ID)Detached Vertex TriggerImproved tracking

D0 enters B physicsNew for Run II

TrackingDetached Vertex Trigger (soon)


Acceptance || < 2.5

Particle ID ATLAS v.limited -K

separation, ~0.8s from TRD

Di-lepton trigger Vertexing

Special pixel B layer R~5cm

“Low” luminosity running Lumi 1033 cm-2s-1

Only 30fb-1 (3 years) Specialist B triggers

BUT : DAQ Bandwidthonly 100 evts/s totape for ALL

physics

ATLAS

Atlas and CMS

From N. Harnew


Forward vs. Central Geometry

b production angle

b production angle

230b

100b

Multi-purpose experiments requirelarge solid angle coverage.

Central Geometry (CDF, D0, Atlas, CMS)

Dedicated B experiments can takeadvantage of

Forward geometry(BTeV, LHCb)


LHCb Light No tracking stations in magnet region Reduced material budget (fringe) magnetic field in tracking

station(s)


The Importance of Particle ID

Purity = 84% ; Efficiency = 90%

B0 h+h-

~17 MeV

For example: B-> +-


The BTeV Detector

Beam Line

Pixel DetectorVacuum Vessel

• 60 pixel planes• inside magnet• = 5-10 m

Proper time resolution: 46 fs

PbWO4 EM Calorimeter

CLEO/BaBar/BELLE-like performance in a hadron Collider environment!

~ 5 MeV

~ 3 MeV

10500 crystals220 mm long, 28x28 mm2

Detached Vertex Trigger • Find the primary vertex• Identify tracks which miss it• Calculates the significance of detachment• For EVERY crossing

b,b/b


Fully simulated bb event using Geant 3• incl. multiple scattering, hadronic interactions• decays in flight• Kalman fitter


Efficiencies and TaggingFor a requirement of at least 2 tracks detached by more than 6, we trigger on only 1% of the beam crossings and achieve the following trigger efficiencies for these states (<2> int. per crossing):

efficiency; D Dilution or (Nright-Nwrong)/(Nright+Nwrong)

Effective tagging efficiency D2

Extensive study for BTeV usesOpposite sign K±

Jet ChargeSame side ± (for Bo) or K± for (Bs)

LeptonsConclusion: D2 (Bo) = 0.10, D2 (Bs) = 0.13(difference due to same side tagging)

Decay efficiency(%) Decay efficiency(%)

B +- 63 Bo K+- 63

Bs DsK 74 Bo J/ Ks 50

B- DoK- 70 Bs J/K* 68

B- Ks- 27 Bo K*


The Physics Goals

There is New Physics out there: Baryon Asymmetry of Universe & by Dark MatterHierarchy problemPlethora of fundamental parameters…

B Experiments at Hadron Colliders are well positioned to:

Perform precision measurements of CKM Elements withsmall model dependence.Search for New Physics via CP phasesSearch for New Physics via Rare DecaysHelp interpret new results found elsewhere (LHC, neutrinos)Complete a broad program in heavy flavor physics

Weak decay processes, B’s, polarization, Dalitz plots, QCD…

Semileptonic decays including b

b & c quark ProductionStructure: B(s) spetroscopy, b-baryon statesBc decays


Part 1: Is the CKM Picture correct?

Use different sets of measurements to define apex of triangle

(adopted from Peskin)

Also have K (CP in KL system)

Magnitudes

Bd mixing phase

Bs mixing phase

Can also measure via B-DoK-

,


Measuring Using Bo

A Dalitz Plot analysis gives both sin(2) and cos(2)(Snyder & Quinn)

Measured branching ratios are:

(B = ~10-5

(B + = ~3x10-5

(B <0.5x10-5

Snyder & Quinn showed that 1000-2000 tagged events are sufficient

Not easy to measure0 reconstruction

Not easy to analyze9 parameter likelihood fit

Slow 0’s

Nearly empty( polarization)

Dalitz Plot for Bo


Yields for BoBased 9.9x106 background events

Bo+-

5400 events, S/B = 4.1

Booo

780 events, S/B = 0.3

o

Background Signal

mB (GeV) mB (GeV)

Booo


Our Estimate of Accuracy on

Geant simulation of Bo(for 1.4x107 s)

Example:1000 Bo signal + backgroundsWith input =77.3o

minimum 2

non-resonantnon- bkgrd

resonantnon- bkgrd

(gen)

Rres Rnon(recon)

77.3o 0.2 0.2 77.2o 1.6o

77.3o 0.4 0 77.1o 1.8o

93.0o 0.2 0.2 93.3o 1.9o

93.0o 0.4 0 93.3o 2.1o

111.0o 0.2 0.2 111.7o 3.9o

111.0o 0.4 0.2 110.4o 4.3o


Bs Mixing (Vtd/Vts)

ms (~xs) = ·C where C can be calculated inside the S. M.

CDF sensitive to xs ~ 30

: Bs-> seen Expect ~ 2% after Run II

BTeV reaches sensitivity to xs of 80

in 3.2 years

6

5

4

3

2

1


One of several ways to determine

BsDsK

Dsmass (GeV)

~ 6.5 MeV/c2

= 168 m

= 418 m

Bs vtx resolution (mm) Ds vtx resolution (mm)

±

• Theoretically clean, BR ~ 10-4


Needed:

Hadronic trigger

K/ separation

Good proper time resolution

Sensitivity depends upon

• relative amplitudes

• strong phase difference• values of , ms s s

For ms=20 ps–1:

1010oo

For ms=30 ps–1:

1212oo

In one year: 8k BsDsK reconstructed

events

from Bs D-s K+ , D+

s K-

(II)

From the measurement of 4 time-dependent asymmetries one gets

same order tree level amplitudes (3) : large asymmetries, NP contributes unlikely

From M. Musy


Measuring In the SM the phases and magnitudes are correlated:

|Vus| = 0.2205±0.0018

is the phase of Vts -> Bs Mixing

Good: Bs->J/ plus non-trivial angular analysisBetter: Bs -> CP eigenstate such as

BsJ/

2 sin sinsin

sin( + )

Silva & Wolfenstein (hep-ph/9610208)Aleksan, Kayser & London


Measuring II

BTeV can reconstruct and ’

Yield in one yearBsJ/2,800 events with S/B = 15

BsJ/9,800 events with S/B = 30

Error on sin(2 = 0.024

With ~ 2o a precision measurement will require a few years.


Physics Reach (CKM) in 107 s Reaction B(B)

(x10-6)# of Events

S/B Parameter Error or (Value)

Bs Ds K- 300 7500 7 - 8o

Bs Ds- 3000 59,000 3 xs (75)

BoJ/KS J/+ - 445 168,000 10 sin(2) 0.017

BoJ/Ko, Ko 7 250 2.3 cos(2) ~0.5

B-Do (K+-) K- 0.17

170 1

B-Do (K+K-) K- 1.1 1,000 >10 13o

BsJ/ 330 2,800 15

BsJ/ 670 9,800 30 sin(2 0.024

Bo+- 28 5,400 4.1

Booo 5 780 0.3 ~4o Reaction B(B)

(x10-6)# of Events

S/B Parameter Error

B-KS -

12.1 4,600 1 <4o +

BoK+- 18.8

62,100 20 Theory err.

Bo+- 4.5 14,600 3 Asymmetry 0.030

BoK+ K- 17 18,900 6.6 Asymmetry 0.020


LHCb preliminary study

(ppBc) ~300 nb 109 Bc/ year

Bc J/BR ~10-2)

~ 2% 12k events/year

Background from B J/X and prompt

J/reduced cutting on the distance between primary vertex and Bc vertex

BBc c mesons mesons

CDF: mBc = 6.4 +/- 0.4 GeV tBc ~ 0.5 ps

BTeV/LHCb: Precisionmeasurements of mass, lifetimeSearch for CPV in Bc -> J/D+

or Bc -> DsD

LHCb acceptance ~30%

M( J/GeV/c2

p (GeV)


Part II: Search for New Physics

For a nice overview see: S. Stone “BTeV Physics” athttp://doe-hep.hep.net/P5StoneMarch2003.pdf


First Example: Supersymmetry

Supersymmetry: In general 80 constants & 43 phasesMSSM: 2 phases (Nir, hep-ph/9911321)

New Physics in Bo mixing: D , Bo decay: A, Do

mixing: K

Process Quantity SM New Physics

BoJ/Ks CP asym sin(2) sin2(D)

BoKs CP asym sin(2) sin2(DA)

DoK-+ CP asym 0 ~sin(K)

New Physics

Difference NP


Rare b Decays Search for New Physics in Loop diagrams

New fermion like objects in addition to t, c or uNew Gauge-like objects in addition to W, Z or g

Inclusive Rare Decays including bs bd bs+

Exclusive Rare Decays such as BBK*+ Dalitz plot & polarization

+-

BoK*


Yield, S/B for Rare b Decays

Reaction B (10-6) Signal S/B Physics

BoK*o+- 1.5 2530 11 Polarization; Rate

B-K-+- 0.4 1470 3.2 Rate

bs+- 5.7 4140 0.13 Rate; Wilson coefficents


BTeV data compared to Burdman et al calculation

Dilepton invariant mass distributions,forward-backward asymmetrydiscriminate among the SM and various supersymmetric theories.(Ali, Lunghi, Greub & Hiller, hep-ph/0112300)

One year for K*+-, enough to determine if New Physics is present

Polarization in BoK*o+-

Ali et. al, hep-ph/9910221


Search also for Bd0

Standard Model BR ~ 1x10-10

Bs0

Standard Model BR ~ 4x10-9

Here the General Purpose Detectorshave an advantage : high pT di-muontriggering at high (1x1034) luminosity.

CMS : 100 fb-1 (107s at 1034 cm-2s-

1) ~26 signal events6.4 events background

Muon trigger :2 ’s with pT > 4 GeV< 2.4

Rare Leptonic Decays


Another Example: Extra Dimensions

Aranda & Lorenzo Diaz-Cruz, “Flavor Symmetries in Extra Dimensions” (hep-ph/0207059) (Buras et al. hep-ph/0212143) Extra spatial dimension is compactified at scale 1/R = 250 GeV on upNo effect on |Vub/Vcb|, Md/Ms , sin(2)

–8%–100

+72%|Vtd|

Bs ->


Summary

Heavy quark physics at hadron colliders provides a unique opportunity to

measure fundamental parameters of the Standard Model with no or only small model dependencediscover new physics in CP violating amplitudes or rare decays.interpret new phenomena found elsewhere (e.g. LHC)

Some scenarios are clear others will be a surprise

This program requires a general purpose B detector like BTeV and LHCb with

an efficient, unbiased trigger and a high performance DAQa superb charged particle tracking systemgood particle identificationexcellent photon detection


Additional Transparenciesfrom BTeV and LHCb Studies


from Bfrom Bss J/J/

In SM S 10-

2 Sensitive to New Physics effects

in the Bs-Bs system In one year:

109 k events Bs J/

19 k events Bs J/e+e

J/is not CP eigenstate:

needs fit to angular distributions of decay final states as a function of proper time

Assuming ms=20 ps–1:

22oo

36±1 fs

From M. Musy


Current status of LHCb Physics Reach in 1 year (2fb–1)

Channel Yield Precision*

Bd J/Ks 119 k 0.6o

Bs DsK

Bd , Bs KK8 k

27 k, 35 k 10o

3o

Bd 27 k 5o- 10o

Bs J/ 128 k 2o

|Vtd/Vts Bs Ds 72 k ms up to 58 ps

rare decays Bd K 20 k

All numbers will be updated together with more channels in the re-optimization LHCb TDR (September 2003)

From M. Musy


A simplified trigger comparison

From U. Egede


Unitarity TrianglesUnitarity Triangles

Bd0

Bd0

Bd0 DK*0

BS0 DSK

Bd0 D*

BS0 DS

Bd0 J/ KS

0

BS0 J/

From N. Harnew

CIPANP2003 K. Honscheid Ohio State The Future of Flavor Physics at Hadron Colliders CIPANP 2003 K....

Documents

Transcript of CIPANP2003 K. Honscheid Ohio State The Future of Flavor Physics at Hadron Colliders CIPANP 2003 K....