Post on 21-Dec-2015
H.Evans U Penn HEP Seminar: 7-Nov-00 1
B-Physics at DØ (coming attractions)
B-Physics at DØ (coming attractions)
Hal EvansColumbia U.
Outline:
I. Why B-Physics?
II. Why DØ?
III. Wild Predictions & Comparisons!
H.Evans U Penn HEP Seminar: 7-Nov-00 2
Philosophy 101(B)Philosophy 101(B)
Why should we study the b-Quark?
1. Probes an area of the SM that is poorly understood CKM Matrix & CP-Violation
2. Sensitive to Physics beyond the Standard Model b-quark is the most massive
fundamental particle that is easily accessible
3. Important input to QCD & models used in other measurements B-Hadron properties lend
themselves to modelling crucial in studying Higgs, t-
quarkLEP EW-WG: Summer 00
H.Evans U Penn HEP Seminar: 7-Nov-00 3
Stalking the Wild b-QuarkStalking the Wild b-Quark Mass (3rd Family) mb ~ 4.5 GeV
couples to t-quark couples to New Physics perturbative QCD regime
Lifetime ~ 1.6 ps a useful ID tool
Spectroscopy light-q mesons: heavy-q mesons: baryons:
Decays ~25 modes meas (B0) 165 modes listed by PDG light quark spectator
Mixing
md~0.47ps-1 ; ms>15ps-1
CP Violation large effects (>10%) in some
modes
0du BB ,
,, 0sc BB
),,(, 0b
00 BB
)B((B)
b s
H±
t
0dB *D
b c
d
W
V*td
b
b
d
dt
tB0 B0W W
H.Evans U Penn HEP Seminar: 7-Nov-00 4
Their Natural HabitatsTheir Natural Habitats
Acceptance at DØ
Tevatron Run II
LEP CLEO B-Fact LHC
Type p e+e- e+e- e+e- pp
Ecm [GeV] 1960 91 10.5 10.5 14000
[b] ~150 0.007 0.001 0.001 ~500
b Rate [Hz] 30,000 0.35 0.3 2 500,000
S/B [%] 0.1 0.15 ~0.3 ~0.3 0.6
<Decay Length> [mm] 2 3 0.025 0.26 1.7 (Lxy)
)bb(
PT(B) > 4 GeV
} Accept ~ 31% |y(B)| < 3.0
H.Evans U Penn HEP Seminar: 7-Nov-00 5
Glorious Tevatron HistoryGlorious Tevatron History
Run I b-Physics Publications CDF – 50 DØ – 7
b Production X-Section + correlations
J/ Production + polarization
Production —
b Fragmentation —
Branching Ratios J/ states —
Masses Bs,Bc,b —
Lifetimes B,B0,Bs,Bc,b —
Rare Decays , K*, e s
B Mixing Bd, Bs
states: manytags: l,Qjet,SST
—
sin 2 J/ Ks0 —
H.Evans U Penn HEP Seminar: 7-Nov-00 6
ch- ch- ch- ch- Changes!ch- ch- ch- ch- Changes!
Major upgrade to the Tevatron nearing completion main injector antiproton recycler
First collisions in 36x36 mode last week !
Ib IIa IIa (?) IIb
Tot. Anti-p (x1012) 0.3 1.1 4.2 11
Bunches 6x6 36x36 140x103 140x103
Spacing [ns] 3500 396 132 132
E-CM [GeV] 1800 1960 1960 1960
Typ. Lumi. [cm-2s-1] (x1032)
0.16 0.86 2.1 5.2
Lumi/week pb-1 3.2 17.3 42 105
Tot Lumi fb-1 0.125 2-4 15-20
Int’s/X’ing 2.5 2.3 1.9 4.8
H.Evans U Penn HEP Seminar: 7-Nov-00 7
DØ Run II UpgradeDØ Run II UpgradeCentral Scintillator
Forward Mini-drift chamb’s
Forward Scint
Shielding
Tracking: Solenoid,Silicon,Fiber Tracker,Preshowers
New Electronics,Trigger,DAQ
Calorimeter
Central PDTs
H.Evans U Penn HEP Seminar: 7-Nov-00 8
Detector PerformanceDetector PerformanceDØ – Run I DØ – Run II CDF – Run II
Field T 0 2.0 1.4
Tracking
accept <3.0 <3.0(Si) ; <1.7 (CFT) <2.0(Si) ; <1.0(COT)
Radii cm 3.7-75 2.8-10.0(Si) ; <52(CFT) 1.6-10.7(Si) ; <132(COT)
PT/PT % — 20.2pt 0.70.1pt
Imp par m — 1350/pt 622/pt
Prim Vtx m 15-30(r) 10-35(r)
Sec Vtx m — 40(r) ; 80(rz) 14(r) ; 50(rz)
Mass res (J/) MeV — 27 16
PID PreShower dE/dx,TOF
accept <4.0 <3.6Calo
0.10.1 0.10.26
EM res % 14/E 16/E
Jet res % 80/E 80/E
accept <3.6 <2.0 <1.5Muon
cover 90% increase scint 80% (cen)
Shield I 12-18 beam shielding 5.5-20
P/P % 18 0.3p —
H.Evans U Penn HEP Seminar: 7-Nov-00 9
Triggering on B’sTriggering on B’s
Handles: Tracks:
rates too high for DØ Leptons: BR(BlX)~11%
only DØ tool at L1 Displaced V’s: <L>~2.3 mm
Si info used at L2 Mass, Isolation, etc…
L2, L3
-
+
-
+
-b
b
/J0sK
Process X-Sect. Rate(L=21032)
Inelastic pp 50 mb 10 MHz
bb (|y|<1) 50 b 10 kHz
pp WX 22 nb 4.4 Hz
ZX bbX 1 nb 0.2 Hz
pp tX 11 pb 8 / hour
pp W/Z H 0.5 pb 8 / day
multi-level trigger required
multi-level trigger required
+
H.Evans U Penn HEP Seminar: 7-Nov-00 10
Triggering at DØTriggering at DØ
L14.2 s
(128 terms)
L2100 s
(128 terms)
L350 ms
(48 nodes)
Framework7 MHz
10 kHz 1 kHz 50 Hz
Data
• Single Sub-Det’s
• Towers, Tracks, ET-miss
• Some correl’s
• Not deadtimeless
• Correlations
• Calibrated Data
• Physics Objects e,,j,,ET-miss
• Simple Reco
• Physics Algo’s
H.Evans U Penn HEP Seminar: 7-Nov-00 11
L1 & L2 SystemsL1 & L2 Systems
L2FW:Combined objects (e, , j)
L1FW: towers, tracks
L2STT
Global L2
L2CFT
L2PS
L2Cal
L1PS
L1CFT
L2 MU
L1 MU
L1FPD
Detector L1 Trigger L2 Trigger
7 MHz 10 kHz 1 kHz
CAL
FPS CPS
CFT
SMT
MU
FPD
L1CAL
H.Evans U Penn HEP Seminar: 7-Nov-00 12
The DØ Silicon Track TriggerThe DØ Silicon Track TriggerTrigger Benefits Improved Momentum Res:
factor 23 Sharper Thresholds
Impact Param at Trigger Resolutions:
~ 30m at PT=2GeV 15m at PT=15GeV
Physics Benefits New Phenomena
incr Higgs sens 20%
ZHbb double sens
hAbbbb Top
Trigger on Zbb (increase yield x6) Cut Mt Syst in half
B-Physics Increase BKS yield by 50%
General Reduce e Rate by a factor of 2
50 s Time Budget
Raw Datafrom Si
Detector
Cluster Finder
Tracks fromFiber Tracker
(L1 Trig)
Associate Clustersto Tracks
Re-Fit Trackw/ Si Clusters
Global L2 Trigger
Define SearchRegion
Online: summer 2002
H.Evans U Penn HEP Seminar: 7-Nov-00 13
DØ Now !DØ Now !
Subsystem Status Future
Silicon all comp’s in handS=done; N>2/3
install S:this week; N:12/00
Fiber tracker Installed finish cabling
Tracker Electr production complete 2/01
Solenoid working
Cen & Fwd Preshowers installed
Intercryostat det. installed
Calorim Electronics production complete 12/00
Luminosity Mon. measuring lumi
Muon Central installed commisioning
Muon Forward installing complete 11/00
Trigger & DAQ prod & use complete 3/01
Online in use help commisioning
Installation on schedule complete 2/01
Computing purchased commissioning
H.Evans U Penn HEP Seminar: 7-Nov-00 14
DØ Ambitions in Run IIDØ Ambitions in Run II
QCD Tests X-Sections & Correlations
Excl. Decays, l+Jet Incl., ll Onium Physics
J/, X-Sect’s and Pol. Fragmentation
B-Hadrons (B,B0,Bs,Bc,b) Spectroscopy Lifetimes Pol. & Helicity Analyses
Rare Decays B l+l-, l+l- K*
Bs K*
B Mixing Bs lX, Ds, J/K*
Bd (t-dep): Tagging Studies
CP Violation & CKM J/Ks
0
sin 2 , KK
(limits) + Bs J/
non-SM
H.Evans U Penn HEP Seminar: 7-Nov-00 15
B ProductionB Production Theory says… Yes!
mb>>QCD: NLO should work but scale uncertainties large
Experiment says… Kinda! normalization x2.5-4 high shape ~OK (but – high vs low PT)
correlations as expected from Higher Order
nagging uncertainty PDFs (note personal bias!)
New for Run II (DØ) exclusive final states vertex tagging electrons more correlation studies
H.Evans U Penn HEP Seminar: 7-Nov-00 16
CP Violation and the CKM MatrixCP Violation and the CKM Matrix
CP Violating Asymmetry
SM expl for CP Asym in K & B: Complex Phase in CKM
Wolfenstein param: O(4)
Unitarity of VCKM 12 eqn’s the Unitarity Triangle is one
b
s
d
VVV
VVV
VVV
'b
's
'd
tbtstd
cbcscd
ubusud
112
11
2
11
23
22
32
A)i(A
A
)i(A
)fB()fB(
)fB()fB(ACP
(0,0) (0,1)
(,)
( ~ sinc)
0 *tdtb
*cdcb
*udub VVVVVV
)KJ/(B 0ψ
VV
VVarg
*tbtd
*cbcd
)(B
*ubud
*tbtd
VV
VVarg
)hh(B
*cbcd
*ubud
VV
VVarg
mixing) (Bts
td
V
V
X)(B
cb
ub
V
V
H.Evans U Penn HEP Seminar: 7-Nov-00 17
but does it All Fit?but does it All Fit? Many measurements
constrain CKM param’s but no real test of whether
CP-violation is described by SM or not
Two Possibilities1. all angle/sides consistent w/
a triangle Hooray for the SM !
2. no triangle fits all meas’s New Physics !
Why expect New Phys here? many beyond SM models
have additional CP-violation matter – antimatter asym not
consistent w/ SM CP
H.Evans U Penn HEP Seminar: 7-Nov-00 18
What can We Do About It?What can We Do About It? Easiest angle to measure is
use time dependent CP asymmetry in BdJ/Ko
Theoretical uncertainties small ! Need to tag Flavor of B at production
remember: it can mix before decaying
)K/JB(N)K/JB(N
)K/JB(N)K/JB(N)t(A
sdsd
sdsdCP 0000
0000
)tmsin()sin( d 2
*
cdcs
cd*cs
*cbcs
cb*cs
*tdtb
td*tb
VV
VV
VV
VV
VV
VVIm)sin( 2
Bd Mixing (f)/A(f)A K Mixing
H.Evans U Penn HEP Seminar: 7-Nov-00 19
B J/ Ks: ExperimentallyB J/ Ks: Experimentally
Experimental Technique measure Lxy t tag initial flavor worry about asymmetric
systematics
Experimental Advantages Leptons for triggering simple, excl final state J/ & Ks mass constr’s
(some) Tagging Possibilities Opposite Side Lepton Opposite Side Jet Charge Same Side Fragmentation
+ -
+
-
+
-b
b
/J0sK
H.Evans U Penn HEP Seminar: 7-Nov-00 20
Opposite side tags: identify the flavor of the other B in
the event soft lepton tags b l - + X jet charge tags Qjet < 0 for b
Same side tags: correlation of flavor and charge of
closest particle produced in fragmentation or decay
Flavor TaggingFlavor Tagging
Efficiency () and
dilution factor (D)
D = 2 P - 1 P is the correct tag probability
D2 is the tag’s effectiveness
Efficiency () and
dilution factor (D)
D = 2 P - 1 P is the correct tag probability
D2 is the tag’s effectiveness
B0
u
d
b
-
B0
b b
u
-
B**- d
H.Evans U Penn HEP Seminar: 7-Nov-00 21
B J/ KS ReconstructionB J/ KS Reconstruction
J/ + -
two muon tracks pT > 1.5 GeV/c | | < 2
H.Evans U Penn HEP Seminar: 7-Nov-00 22
B J/ KS ReconstructionB J/ KS Reconstruction
•KS + -
• pT () > 0.45 GeV/c
• pT (KS) > 0.75 GeV/c
• | | < 1.8
• Lxy/ > 5
•Combined +- +-
invariant mass • (before fit)
H.Evans U Penn HEP Seminar: 7-Nov-00 23
B J/ Ks decay length reconstructionB J/ Ks decay length reconstruction
• Two secondary two-track vertices
• Average B decay length: 2.3 mm
• Measured decay length resolution: 100 m
H.Evans U Penn HEP Seminar: 7-Nov-00 24
BJ/Ks ReconstructionBJ/Ks Reconstruction
J/+-
2 Muons: ||<2.0, PT>1.5GeV
Ks+-
Long lifetime rejects bgrd Lxy/ > 5
4-Track Constrained Fit mass: J/, Ks
vertex: KsB, B primary
Decay Length Resolution 100 m
unconstr:
= 41 MeV
constr:
= 10 MeV
H.Evans U Penn HEP Seminar: 7-Nov-00 25
EffectivenessEffectiveness
Tag
D 2 (%) measured
CDF Run I
D 2 (%) expected
CDF Run II
Relevant
DØ difference
DØ capabilities
Same side 1.8 2.0 same 2.0
Soft lepton 1.7 e ID
coverage 3.1
Jet charge 0. 8 3.0 forward tracking 4.7
Opp. side K 2.4 no K ID none
Combined 9.1 9.8
Measure of tagging weight
• Quality = D2
• = efficiency of tag
• D = (2P – 1) P = correct tag prob
H.Evans U Penn HEP Seminar: 7-Nov-00 26
sin(2) Expectations (2 fb-1)sin(2) Expectations (2 fb-1)
DØ Assumptions: S/B ~ 0.75 D2 = 9.8% Time res: t ~ 100 fs 2.0 fb-1 of data
S
B
NDx
xe)(sin
d
dx td
11
2
412
2
2222
J/+- J/e+e-
Trig Eff (%) 27 20
N(reco evts) 40000 30000
sin(2)0.04 0.05
0.03
H.Evans U Penn HEP Seminar: 7-Nov-00 27
sin2 Past, Present & Futuresin2 Past, Present & Future
Exp. Meas N(events) D2 (%) Data
Opal LEP1
Aleph 23 LEP1
BaBar(*) 0.12±0.37±0.09 120 27.9 9.0 fb-1
Belle(*) 98 21.2 6.2 fb-1
CDF Run I 395 ~2.0 0.11 fb-1
Run II ±0.043 28K() 9.1 2.0 fb-1
DØ Run II ±0.03 40K()+30K(e) 9.8 2.0 fb-1
BTeV ±0.017 109K 10 1 year
HeraB ±0.16 720 1 year
Atlas ±0.017 160K()+5K(e) 3() – 30(e) 1 year
CMS ±0.015 490K()+40K(e) ~3 1 year
0.53.2 1.82.0-
0.160.84 0.821.04-
0.410.44-0.79
0.070.09-
0.430.44-0.45
(*) Preliminary
H.Evans U Penn HEP Seminar: 7-Nov-00 28
Rare Decays and FCNCsRare Decays and FCNCsTheoretically FCNC B0 decays forbidden at
tree level in SM
Beyond SM effects could be large !
Experimentally Triggering
Leptonic Modes: easy
Event Reconstruction +-
easy – but low BR B mass secondary vertex isolation
+-K*
promising all of above + K* ID cut out resonances
+-Xs
difficult small M() window large backgrounds
b s
W
tb s
H±
t
Mode BR(Bd) BR(Bs)
+- 1x10-10 4x10-9
+-K* () 1.5x10-6 1x10-6
+-Xs 6x10-6
K* 4.4x10-5
H.Evans U Penn HEP Seminar: 7-Nov-00 29
Beyond the SM w/ Rare DecaysBeyond the SM w/ Rare Decays
+-
in 2 Higgs-Doublet Model
+-K*
)pp(N)pp(N
)pp(N)pp(NA
2
2
W
bSMHDM M
tanm
Ali,Ball,Handoko,Hiller – hep-ph/9910221
SM MIA-SUSY(C10)>0
SUGRA
MIA-SUSY
H.Evans U Penn HEP Seminar: 7-Nov-00 30
Bd+-K* AsymmetryBd+-K* Asymmetry
Expect ~700 events in 2 fb-1
Asymmetry results (plot d) A = 0.11 ± 0.11 m < 2 GeV A = -0.33 ± 0.06 m > 2 GeV
To do Bde+e-
B+l+l-K+
Generated distrib’s
Reconstructed: no bgrd (a,b)
Reconstructed: S:B=1:1 (c,d)
)pp(N)pp(N
)pp(N)pp(NA
H.Evans U Penn HEP Seminar: 7-Nov-00 31
Big List o’ PredictionsBig List o’ Predictions
State N(evts) Meas. Sens Current
BdJ/K0 70K sin2~0.03 sin2=0.48±0.23
Bd+- 300-600 ? B=(9.3±2.9)x10-6
BdK+- 1300-1600 ?B=(12.5±3.3)x10-6
Bs+K- 150-300 ?
BdK+K- 650-1300 ? B<4.3 x10-6
Bs Mixing 700-2100 xs=20-30 xs>22 ps-1
b 30K-80K (b)~0.16 ps (b)=1.23±0.08 ps
BcJ/l 600 ? m(Bc)=6.4±0.4 GeV
(Bc)=0.46±0.18 ps
B+-K* 700 A~0.06 B<4.0x10-6
B+-Xs 1000 (S/B=0.03-0.1) ? B<5.8x10-5
B+- 0 (if SM) ? B<6.8x10-7all predictions for 2 fb-1 of data