beauty in the prairie - nevis laboratoriesevans/talks/uw_seminar03.pdf · h.evans uw hep seminar -...

H.Evans UW HEP Seminar - 30-Oct-03 1

Beauty in the Prairie(you find it in the strangest places)

Beauty in the Prairie(you find it in the strangest places)

Hal Evans Columbia University

1. Why the b-Quark ? (broad goals of HEP)

2. Why at DØ ? (b-physics at hadron colliders)

3. How Do You Do It ? (Bs mixing as an example )

4. What Do You Get ? (where does it all fit in)


Standing on Solid GroundStanding on Solid Ground

mf2>114H0E-W Sym

10-1 (MZ)0gStrong91.1882Z0

10-580.419W±Weak10-20γE-M10-390GGravity

StrengthMass[GeV]

BosonForce Carriers

4.41503–9-1/3bsd

17430013001–5 +2/3tcu

Quarks

Leptons

17771050.5-1τµe

υµ O(<eV)0υτυe

Mass[MeV]

Chg[e]

Matter (fermions)

LEP EW-WG


If it ain’t Broke – Fix It !If it ain’t Broke – Fix It !Why Look Beyond the SM ?

• Has 19 arbitrary parameters

• Higgs Mass not stable to radiative corrections

Λ ~ Mplanck for no new phys Mh < 800 GeV

⇒ tuning to 10-16

• No Motivation for EW Symmetry Breaking

• Does not include Gravity∗ Why Mpl >> MEW?

222

20

2

4 hhh MM~M δ+Λπλ

+


Where Should We Look ?Where Should We Look ?

Start with the BIG Questions1. Why is there Mass ? EW Symmetry Breaking

2. Antimatter ? Weak vs Mass States & CPV

3. What about Matter ? understanding QCD

Look in New Places• Sparse Measurement ⇒ Lots of Options

• The Winning Candidate: EW Symmetry Breaking ! turns out to be related to question 2) as well


The Symmetry–Flavor ConnectionThe Symmetry–Flavor Connection

• The SM has a Lovely Plan for EW Symmetry Breaking

• SM Symmetries & Yukawa Couplings ⇒ Quark Mixing

• Mixing (CKM) Matrix: Vij

Gives observed Flavor Structure of SM: Weak≠Mass States

.]c.hUQyDQyELy[L jR

iL

uij

jR

iL

dij

jR

iL

familyj,i

eijY +φ+φ+φ∑−=

=

diagonal-non s,comp' imag.

diagonal real, )convention (by

=

=dij

uij

eij

y

y,y

∑ ∑ +φ−+φ−=i j,i

jRij

iL

dj

iR

iL

uiY .]c.hDVQy[]c.hU~Qy[L

b u

W-

2ubgVFamily Changing

Decays Mixing

s

t

t

s

b

b

WW0sB 0

sB


Quarks are all mixed up !Quarks are all mixed up !Unitarity of VCKM ⇒ 6 triangles

one has all sides ~ equalQuark Weak ≠ Mass Eigenstates

3 angles 1 complex phase

⇒ CP-violation

Wolfenstein Parameterization

=

bsd

VVVVVVVVV

'b's'd

tbtstd

cbcscd

ubusud

λ−η−ρ−λ

λλ−λ−

η−ρλλλ−

11211

211

23

22

32

A)i(

A

)i(A

0=++ *tdtb

*cdcb

*udub VVVVVV

(0,1)

γ β

α

(ρ,η)

− *

ubud

*tbtd

VVVVarg

*cbcd

*tbtd

VVVV

− *

tbtd

*cbcd

VVVVarg

− *

cbcd

*ubud

VVVVarg

*cbcd

*ubud

VVVV

UnitarityTriangle

A

(0,0)


Why is Flavor Promising (1)Why is Flavor Promising (1)

The SM has a very Specific Flavor Sector:Only one Higgs Doublet

1. FCNC’s suppressed

2. Universal Charged Current

3. VCKM is Unitary

4. 1 Parameter describes strength of all CP Violation


Why is Flavor Promising (2)Why is Flavor Promising (2)• Other Models much less restricted than SM• But – strong constraints from existing measurements in K and

B sectors 3rd generation least constrained

Use Flavor to Select Among Classes of Models:1. Most Generic Models already ruled out

flavor physics is an input to model building2. Flavor Suppress. in 1st two gen’s Randall-Sundrum

large effects in B-systems3. Flavor Suppress. in u-sector SUSY w/ alignment

large effects in charm4. Generic Flavor Suppression Split Fermions in FED

large effects in flavor physics5. New Physics is Flavor Blind (MFV) GMSB

small effects in flavor physicsYuval Grossman: Lepton-Photon 2003


Beauty as a ProbeBeauty as a Probe

B-Physics is a Good Place to Probe EW Sym. Breaking measurable unitarity triangle QCD corrections to predictions small

1. Look for Modifications to Couplings Different EW Sym. Breaking Struct. ⇒ Different Couplings Most Interesting Channels = Rare or Zero in SM

2. Check Consistency of CKM Picture Many meas’s sensitive to CKM magnitudes & phases

∗ Rates, Mixing ⇒ Magnitudes (sides of U.T.)∗ CPV Asymmetries ⇒ Phase (angles of U.T.)∗ general measurement can depend on several U.T. param’s

These should all form a single triangle if the SM is correct∗ other models predict different relationships


So Far – It All Fits (damn!)So Far – It All Fits (damn!)Current Constraints

B → J/ψ K0,η,η’ β B → X l v α-γ side Bd,s Mixing α-β side εK CPV

⇒ Consistent SM Picture

Future Constraints B → φ K0 β Bs → J/ψ φ βs

B → ππ, ρρ α B → πK, KK, DK γ K → π v v Vtd

+ many more!⇒ There’s still hope!


Fermilab & Flavor PhysicsFermilab & Flavor PhysicsHistory

Commissioned 1967∗ first director Robert Wilson

Tevatron (p-pbar) 1983 Main Injector 1999

Some Highlights b-quark discovery: 1977

∗ Lederman, et al t-quark discovery: 1994

∗ CDF & DØ υτ discovery: 2000

∗ DONUT


The Tevatron ColliderThe Tevatron ColliderWorld’s Highest E Accelerator

~4 miles circumference >1000 supercond. magnets

Main Injector(new)

Tevatron

DØCDF

Chicago↓

p source

Booster

272223(x1010)p/bch

196019601800[GeV]E-CM

132.25.5(x1010)Anti-p/bch

36x3636x366x6Bunches

<10.220

6

4

396

IIa(now)

>102.5Int’s/X’ing4-90.125fb-1Tot Lumi553.2pb-1Lumi/week

290.16[cm-2s-1]Peak Lumi. (x1031)

3963500[ns]Spacing

IIa(goal)

Ib92-96


b’s in the Wildb’s in the Wild

0.6~0.3~0.30.150.1[%]S/B

25,000100.80.07600[Hz]Reco Rate

allBd,B+Bd,B+allallSpecies Prod

1.7 (Lxy)0.260.02530.45[mm]<L>

1×10331×10347.5×1032~10311×1032[cm-2s-1]Luminosity~5~100~100~100~6[%]Reco’able

~5000.0010.0010.007~100[µb]

1400010.510.5911960[GeV]Ecmppe+e-e+e-e+e-Collisions

LHCB-FactCLEOLEPTevatronRun II

pp

)b(bσ


DØ CollaborationDØ Collaboration

646 people73 institutions18 countries


Central Scintillator

Forward Mini-drift chamb’s

Forward Scint

Shielding

Tracking: Solenoid(2T), Silicon,FiberTracker,Preshowers

New Electronics,Trigger,DAQ

Calorimeter

Central PDTs

DØ Detector (the cartoon)DØ Detector (the cartoon)


The Real McCoy !The Real McCoy !

• ~1M Channels

• 2.5M Event/s

• 250 KB/Event


DØ à la carteDØ à la carte

DØ is a General Purpose DetectorDesigned to Study a Huge Range of Physics Topics

• Directly look for new particles/effects predicted by specific beyond the SM models

Searches• The heart of EW symmetry breakingHiggs

• Precision measurement of EW parameters• Most massive particle ⇒ new physics

Top

• QCD Tests• Precision measurement of EW parameters

W/Z

• QCD at perturb/non-perturb interface• Probe quark mixing• Indirect evidence for new physics

B Physics

• Understand the strong force where it is predictive• Background for all other physics

QCD


B Measurements to WatchB Measurements to Watch

• Confidence Builders needed for other meas’s Lifetimes Bd Mixing

• b-Production resolve previous discrep’s b-production x-section & correlations J/ψ & Υ production mechanisms

• b-Spectroscopy only place to see these Bs, Bc, B-Baryons

• Rare Decays sensitive to beyond SM B → µ+ µ- / µ+ µ- K*

• CP Violation competitive w/ B-Fact’s sin(2β) from B → J/ψ K0

s

• Mixing big impact on CKM fits Bs Mixing


Rare Decays and FCNCsRare Decays and FCNCs

4.4x10-5K*γ

1x10-6

4x10-9

BR(Bs)

6x10-6µ+µ-Xs

1.5x10-6µ+µ-K* (φ)1x10-10µ+µ-

BR(Bd)Mode

2

2

βΓ∝Γ

W

bSMHDM M

tanm

Theoretically Clean• FCNC B0 decays forbidden at

tree level in SM• Can be large beyond SM

Plays to DØ’s Strengths• Leptonic Triggering• Event Reconstruction

µ+µ-

∗ B mass, vertexing, isol. µ+µ-K*

∗ K* ID, no ψ resonancesµ+ µ- Mass [GeV]

s

Preliminary LimitBR(B → µ+ µ-) < 1.6×10-6 (90% CL)s

Preliminary LimitBR(B → µ+ µ-) < 1.6×10-6 (90% CL)


B MixingB MixingWeak ≠ Mass Eigenstates

⇒ Neutral B’s can mix

Time Evolution

Sensitive to |Vtd|

World Averages (HFAG ’03) ∆md = 0.502 ± 0.006 ps-1

∆ms > 14.4 ps-1 (95% CL)

matrices 2x2 Hermitian 2

=Γ

Γ

−=

,M)t(B)t(B

iM)t(B)t(B

dtdi

1[

1[00

00

tmcos(e)t)(BB(P

tmcos(e)t)(BB(P

qt

qq

qt

qq

q

q

∆−∝→

∆+∝→Γ−

Γ−

s

d

Bd

Bs

BdBd

BsBs

ts

td

mm

mm

BFBF

VV

∆∆

=

sd,

t

t

s,d

b

b

WW0sd,B 0

sd,B

*tbV

tbVstd,V

*std,V

]

]

)

)


Anatomy of a Bs Mixing AnalysisAnatomy of a Bs Mixing Analysis1. Identify Bs Candidates

produce them get them to tape reconstruct them

2. Determine Proper Time decay length ct = L / γβ

3. Mixed or Unmixed flavor at production flavor at decay

4. Fit for ∆ms or ampl at ∆ms

+π

−µ−π

+π

ν-B

−K0D

0sB

-sD

−K

+K

Sensitivity

N = no. of Bs candidates ε = frac. of Bs in N D = 1 – 2xProb(mistag) S/B = signal/ bgrd in N σt = ave. proper time res.

22

2

2Signif /)m( tse

BSSDN σ∆−×+

ε=


Finding the Elusive BsFinding the Elusive Bs

+π

−µ−π

+π

ν-B

−K0D

0sB

-sD

−K

+K

Experimental Challenges 20–40% of Bs out of accept

when trigger on opp. lepton Low Pt trigger lepton Low Pt tracks

+l

−µ−π

+π

ν-B

−K0D

0sB

-sD

−K

+K

ν

1. Produce a Bs fs ~ 0.1 vs. fd = fu ~ 0.4

2. Trigger on the Event L1 is the bottleneck Di-µ (Pt>3, |η|<2.2) no presc. Di-µ (Pt>1.5, |η|<2.2) prescale 1- µ (Pt>3-5, |η|<2.2) prescale

3. Reconstruct Bs Ds

(*) l v BR ~ 10%∗ more stat’s poorer σt

∗ (can trigger on lepton) Ds

(*) nπ BR ~ 0.5%∗ less stat’s better σt

Ds → φπ, φlv (φ →KK)


We Reconstruct B’s !We Reconstruct B’s !

B± → J/ψ K± Bd → J/ψ K* Bd → J/ψ Ks0

B → µ D± X

Λb → J/ψ Λ

B → µ D* X


…And Even Bs…And Even Bs

~1 event / pb-130 – 40 events / pb-1


How Long Does It Live ?How Long Does It Live ?

+π

−µ−π

+π

ν-B

−K0D

0sB

-sD−K

+K

1. Estimate Decay Length (Lxy) Beam Spot

∗ size ~35 µm in x-y∗ average vs. evt-by-evt

Bs Decay Point∗ vertexing

Decay Length Error (σL)

2. Estimate B Momentum Bs → Ds

(*) π very precise Bs → Ds

(*) l v missing v must use MC to est. corr.

3. Proper Time & Error

Experimental Challenge understand resolution

KPMLct meast

Bxy

=

22

0

2

στ

+

σ=

τσ

Kt

LK

BB

L

B

t


Study Resolution with LifetimesStudy Resolution with Lifetimes

200(67%) / 450(33%)1.60 ± 0.021.460 ± 0.083B → D0 µ X~1101.461 ± 0.0571.19 +0.19/-0.16 ± 0.14Bs → J/ψ φ~1101.542 ± 0.0161.51 +0.19/-0.17 ± 0.20Bd → J/ψ K*0

~1001.674 ± 0.0181.65 ± 0.08 +0.09/-0.12 B+ → J/ψ K+

~1001.562 ± 0.013 ± 0.045 B → J/ψ XResolution [fs]PDG Ave. [ps]Lifetime (stat,syst) [ps]Mode

B+ → J/ψ K+

114 pb-1

B+ → J/ψ φ

114 pb-1

B+ → D0 µ X

12 pb-1


To Mix or Not To MixTo Mix or Not To Mix

+π

−µ−π

+π

ν-B

−K0D

0sB

-sD

−K

+K

+h

1. Tag Flavor at Production using Opposite Side Soft Lepton (muon) Tag

∗ µ-charge ⇒ b-charge Jet Charge Tag

∗

2. Tag Flavor at Production using Same Sidea. Charge of leading non-Bs

hadron∗ B** → B h or fragmentation

3. Tag Flavor at Decay D-charge ⇒ b-charge

∑∑

=i,t

ii,t

PqP

Q Jet

Experimental Challenge Measure mis-tag rate in Data B+ → J/ψ K+ are a perfect lab


Controlling it with B+ → J/ψ K+Controlling it with B+ → J/ψ K+

B-

MC B+

MC

B** → B+ π-

5.5 ± 2.02679Same Side3.3 ± 1.72747Jet Charge1.6 ± 1.1575Soft Muonε D2 (%)D (%)ε (%)Method


Wild ProjectionsWild Projections

• Add electron modes

• Combine Results

⇒ Sensitivity to SMFit Region

Sensitivity for1 fb-1

11010.51.41-µDs(*) π

15010.542-µDs(*) µ X

150σt (fs)

10.1301-µDs(*) µ X

S/BεD2 (%)Yield / pb-1TriggerMode


The Road AheadThe Road Ahead• Need to Establish Bs Mixing Measurement

systematic studies: tagging, resolution Lifetimes & ∆md measurements

• And Make Improvements include electron modes better resolution & momentum estimates

• But the Measurement is within Our Grasp !

• And That’s Not All ! sin(2β) from J/ψ Ks

0 & J/ψ φ Rare Modes: Bs → µ+ µ- & Bd → µ+ µ- K*

Studies of the Bc & Λb Precise measurements of production


Backup SlidesBackup Slides


Stalking the Wild b-QuarkStalking the Wild b-QuarkMass (3rd Family) mb ~ 4.5 GeV• couples to t-quark• couples to New Physics• perturbative QCD regime

Lifetime τ ~ 1.6 ps• a useful ID tool

Spectroscopy• heavy-light mesons:• heavy-heavy mesons:• baryons:

Decays ~25 modes meas (B0)• 165 modes listed by PDG• light quark spectator

Mixing• ∆md~0.5ps-1 ; ∆ms>14ps-1

CP Violation•• large effects (>10%) in some modes

0du BB ,±

Υ± ,, 0sc BB),,(, ΩΣΞΛ0

b

00 BB ↔

)B((B) Γ≠Γ

b s

γ

H±

t

0dB −*D

b c

d

+l+W lν

s

t

t

s

b

b

WW0sB 0

sB


DØ Data So FarDØ Data So Far


Tevatron ProjectionsTevatron ProjectionsTotal Lumi

8.64.4FY096.23.3FY083.82.1FY072.21.5FY061.41.0FY050.70.6FY040.30.3FY03

DesignBase[fb-1]


Some PiecesSome PiecesSilicon Detector

Muon Detector

Fiber Tracker

Calorimeter & Toroid


Trigger HappyTrigger HappyConclusion: too much Physics!

2.5 MHz(396 ns)

Beam X’ing

*m(H)=100 GeV56%22%

7 / day425 fb44%→only jets35%→e/µ + jets

~100%5 / hour7.2 pb0.2 Hz1 nb4.4 Hz22 nb10 kHz50 µb10 MHz50 mb

Rate(L=2x1032)

X-Sector BR

Process

L14.2 µs

(128 terms)

L2100 µs

(128 terms)

L350 ms

(48 nodes)

2.5 MHz• Single Sub-Det’s

• Towers, Tracks,ET-miss

• Some correl’s

• Not deadtimeless

• Correlations

• Calibrated Data

• Physics Objects e,µ,j,τ,ET-miss

• Simple Reco

• Physics Algo’s

3 kHz

1 kHz

50 Hz

F’work

Data

pp Inelastic)( bbpp 1y <→

WXpp →XbbZXpp →→

ttpp →

bbWW -+→

H(*) W/Zpp →bb e/ +µ

bb qq +


DØ L1 & L2 TriggersDØ L1 & L2 Triggers

CAL

c/f PS

CFT

SMT

MU

FPD

L1Cal

L1PS

L1CTT

L1Mu

L1FPD

L2Cal

L2PS

L2CTT

L2STT

L2Mu

Global L2Framework

Detector

Lumi

Level 1 Level 27 Mhz 5 khz 1 khz

Level 3


ResonancesResonances

σ = 7 MeV

σ = 3 MeV


The J/ψThe J/ψ

114 pb-1

beauty in the prairie - nevis laboratoriesevans/talks/uw_seminar03.pdf · h.evans uw hep seminar -...

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