Flavor Physics
description
Transcript of Flavor Physics
Flavor Physics• CKM Matrix
• B Physics– Production– New States– Lifetimes
– Bs Mixing
– CP Violation– Other Measurements
• Top Physics– Production– Spin Correlation– W Polarization
– Vtb
Quarks: Flavor
Vud Vus Vub
Vcd Vcs Vcb
Vtd Vts Vtb( )CKM Matrix of Flavors: u,d,c,s,t,b
1-2/2 A3(-i)
1-2/2-i A24 A2
A3(1--i) -A2 1( )Wolfenstein Representation
Different Processes give different elements
FNAL CKM Measurements“KTeV”,“KAMI”
“CKM”
B Physics Colliders?
CP violation in B decays
(1,0)
Vtd
Vts
(0,0)
()
Vub*
Vcb
Measured by CLEO+LEP at level
Ratio md/ms or
radiative B decays
ACP in B0J/ Kos
ACP in B0
ACP in Bs0Ds
B Physics: Production• Central Rapidities
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B Physics at the Tevatron
bbbbbp
Bd0 , B , Bs
0 , Bc , b all
produced
Two main trigger samples: J
high pt leptons
To improve S/N:• good mass resolution• displaced vertex cuts
SELECTED CDF RESULTS
– M(B ) = 5279.1 ± 1.7 ± 1.4 Mev/c2
M(Bd0) = 5281.3 ± 2.2 ± 1.4 Mev/c2
(Bs0 ) = 1.36 ± 0.09 ± 0.06 ps
(Bs0 )/ (Bd
0 ) = 0.899 ± 0.072
– Bc discovery
Prompt J/
J/from B’s
Side-band background
J decay length
B Physics: Heavier States
• Bc Observation
B_c Lifetime
B_c
B Physics: Lifetimes
• Neutral and Charged very close
• Note higher mass states Bs, b
A(t) = = cos ( mqt)
reconstruct B-decay measure displaced vertex tag B-flavor at production:
• Soft Lepton Tagging (SLT)• Jet Charge Tagging (QJT) • Same Side Tagging (SST)
CDF has five independent Bd0 mixing measurements:
md = 0.481 ± 0.028 ± 0.027 ps-1
CDF has also limits for Bs0 mixing:
ms > 5.8 ps-1 @ 95% CL from Bs0lX
ms < 96 ps-1 @ 95% CL from Bs0Dsl anal.
Bd0 and Bs
0 mixing
b W d, s
BodBo
d
Wd
uct b
uct
tt
tt
Vtb1
VtdOpposite side tagging
Like-sign asymmetry vs decay-length
Xq= mq/q Vtq
sin (2) measurement
• ACP(t) = = sin (2) sin (mdt) f is J/ Ks0
Measured asymmetry: Amea(t) = DACP(t)
Use multiple B flavor tagging algorithms: SST SLT JCTD2 (%) 1.80.5 0.910.15 0.780.14
sin @ 93% CL (Feldman-Cousin statistics)
Important Demo at least!!!
tf tf
tf tf
B
BS
ND
1)2(sin
2
16.039.079.0)2sin(
RUNII : sin 2
SIN(2) FLAVOUR TAGGING D2 CDF I CDF II CDFII +TOF
SST() 1.8% 2.0% 2.0% JCT 0.8% 3.0% 3.0% SLT 0.9% 1.7% 1.7% KAON - - 2.4%
SIN(2) SENSITIVITY
– statistics of fully reconstructed B-decays is expected to increase by:
Run II luminosity bb(s) increase
Efficiency x Acceptance e+e- channel
For 2fb-1 :
CDF II(sin 2) = 0.078
CDF II+TOF (sin 2) = 0.067D0 (sin 2) =
0.10
1801.1 2 4 20
B Physics Measurements
• Bs Mixing
– use states…...
– 20,000 Bs with SVT trigger– tagging using ….
xs Reach 40 - 60
B Physics: Other Measurements
• CP Violation in Bs
– Bs J/
• sin 2 , sin 2 – ( tough, need rate, id, space resolution)
• Rare Decays
A Rich and Extensive Program in good part beyond the B Factory reach
Asymmetry error vs. xs
Assuming BR(t Wb) = 100, the measured top quark pair-production cross section agrees well with the SM prediction.
Top Quark Production Cross Section
(DØ) tt= 5.9 1.7 pb
(CDF) tt= 7.6 1.8 pb
New CDF top production cross section:
6.4 pb.1.51.3
(NEW!)
W Polarization in Top DecaySM predicts fraction of longitudinally polarized W’s
from top decay: F0 = M2top/(Mtop
2 + 2MW2) =
0.70
Extract W helicity fractions from the shape of thecharged lepton pT spectrum in t bW b
• better measured than angular correlations• unaffected by reconstruction or combinatorics
• assume a mixtureof longitudinally
polarized andnegative helicity
W’s producedin top decay
• use a maximumlikelihood method
to estimate F0(assume positivehelicity fraction
F+ = 0)
F0 = 0.97 0.37 0.12
(assume F0 = 0.75) F+ = 0.11 0.15 0.06