Other B physics at the Tevatron

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Other B physics at the Tevatron Presented by
Petros Rapidis (Fermilab, DØ) On behalf of the
CDF and DØ Collaborations WIN2003 October 6
11 ,2003 - Lake Geneva, Wisconsin
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Run-II inclusive J/? cross section and
determination of the total b quark production
(CDF)
Run-I measurements of high pT b cross sections
are factor of 2 larger than QCD NLO prediction
a problem even though more recent theoretical
work has reduced this to an acceptable level of
r 1.7 .5 (thy) .5 (exp).
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Starting point is the measurement of inclusive J/
? production (reported by Kai Yi) Based on L
39.7pb-1 , and uses a dimuon trigger and
covers all the J/? pT range ? ( pp?J/?,
ylt0.6) Br(J/? ???-) 240 ?1 (stat)
?30(syst) nb
_
?
B-fractions from Lxy/pT distributions
J/? needs boost MC study of b? ?X
production For pT(?) 1.0 to 1.25 GeV pT(b) gt
0,2 GeV ? ?ßctgt 45 microns
?
d?(Hb?J/?)/dpT(J/ ?)
Results were unreliable unless pT(?) gt1.25 now
apply acceptance correction
?
d?(Hb?J/ ?)/dpT(Hb) and ?total(Hb?J/ ?)
pT(Hb) ? pT(J/?) correlation needs to be
deconvoluted
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Example of fitting results
10 -12 GeV
--B contribution, --Prompt fake J/?,
--Total Fit
1.25 -1.5 GeV
B-fraction results
Systematic error is dominated by resolution
(1-8) and MC input spectrum (2-7)
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Differential cross section for B?J/?
d?(Hb?J/?)BR d?(inclusive)BR fb
A(B)/A(inclusive)
Systematic error (10-20) is dominated by the
J/Psi polarization uncertainties in the
acceptance calculations ?0.15 ? 0.3
(inclusive) ?0.0 ? 0.5 (B?J/?)
To extract a cross section one has to unfold the
pT(Hb) ? pT(J/?) correlation
pT(b) distributions from some pT(J/?) bins
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Differential d?/dpT(B) as function of pT(B)
Total b quark cross section at Tevatron using
BR(B ?J/?) 1.16 0.10 and BR(J/? ???-)
5.88 0.10 ( from PDG 2003) ?(pp?b,
ylt0.6) 18.0 ? 0.4(stat) ?3.8(syst) ?b (single
b quark) ?(pp?b, ylt1.0) 29.4 ? 0.6(stat) ?
6.2(syst) ?b (single b quark)
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Work in progress (D0)
Early version of B jet cross section Uses an old
version of the software, and a miniscule amount
of the total luminosity (5 pb-1)
To be updated !!
L 113 pb-1
A significant sample of J/?s Soon to be
increased by x2 (luminosity) and by 1.6 (better
fitter) Expected total 1 000 000 psis
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Observation of B hadrons with the DØ Detector
B
?b
These signals have been used to determine
lifetimes (presented in another talk
S. Burdin)
Luminosity 114 pb-1
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Search for the decay Bs ???- (DØ and CDF)
An interesting channel because for a large part
of the parameter space of the MSMM this rate is
larger than the one expected by the SM by a
factor of 1000. SM expectation is 3.8 ? 1.0 x
10-9 Limit until now was from Run I CDF
at the 90 C.L.
DØ analysis
Two good muons (see spectrum below) Lxy gt 550
microns and ?(Lxy)lt150 microns along the Bs
direction (i.e. use long lived Bs) Txy lt 2?
- component of displacement perpendicular to the
Bs momentum (removes non-primary vertex
backrounds) PT (of Bs ) gt 4.0 GeV/c Muon
isolation (
L 100 pb-1
) within ?Rlt1 of muon pair to be less than 0.39
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DØ Run II Preliminary - L 100 pb-1
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using Feldman- Cousins method
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CDF analysis
Based on 113 pb-1
Discriminating variables are m(??-) , c? , ??
, isolation ?? pointing consistency (angle
between sec. vertex vector and B momentum
vertex) isolation is
, within ?Rlt1 of muon pair
One event survives and falls into both the Bs and
Bd mass windows. A very detailed study of
backgrounds as a function of the isolation
parameter and the muon pair mass gives an
expectation of 0.54 ? 0.20 and 0.59 ? 0.23
background events events respectively.
BR(Bd ???- ) lt 2.5x10-7 at the 90 C.L. (this
is approx. x2 weaker
than BaBar/Belle limits)
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B???K? (CDF) in comparison to B?? J/?K? Two
Track Trigger sample ????1.4 , 3 Silicon hits,
25 axial 25 stereo COT hits Lxy ?
200 microns, IP(B) ? 100 microns Impact
parameter for tracks gt 100 microns PT(non trigger
K) ? 1.5 GeV/c, isolated ( gt0.5 ) Select ? and
J/? mass regions
A small signal is observed and one can set the
following limits
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Bs? K?K? (mostly) but also B0? h?h? (CDF)
Analysis technique similar to the ones previously
presented. Based on 65 pb-1 Lxy gt 300 microns,
impact parameter of both tracks gt 150
microns, impact parameter for the B lt
80 microns, and isolation cut gt
0.5 Problem how to disentangle the four
contributions Bd? ???? , Bd? K?- , Bs? K-?
, Bs? K?K? (and CC states) with
limited particle identification capabilities. (
dE/dx is the only handle, and this provides 1.16
sigma ?/K separation !) Use a statistical
(weighting) process, where a parametrization and
fit is done in two parameters M ? ? - the
invariant mass of the track pair assuming pion
masses for both tracks and
where p1 is the smaller
and p2 the larger 3-d momentum, and q1
the charge for the
particle with the smaller momentum
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A likelihood function combining a background
parameterization (extracted from mass sidebands)
and a weight for each event depending on its M
and ? values is used to estimate the number of
events.
Raw particle fractions are (total no. of
events is 280 26)
and the yield of Bs? K?K? 90 ? 17(stat) ?
17(syst)
PDG shows 0.25 ? 0.06
ACP(Bd? K? -) 0.02 ? 0.15 (stat) ? 0.017
(syst)
BaBar has -0.102 ? 0.050? 0.016
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B mass measurement (DØ )
A conglomeration of 4 excited B mesons states
(that are not resolved) Studied via the fully
reconstructed decays
Based on 115pb-1 where there were 1193 ? 52 B
and 463 ? 38 Bd (fully reconstructed)
Good vertex (?2lt16) , PT (p) gt 0.9 GeV , at least
two Si hits
Compare the right charge combination i.e.
To the wrong charge combination
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Plot the mass difference of B and the B
Signal seen in the B
d channel of 65 ? 17 Bs
No signal in the B channel, but expectation
was 16?7 Bs
?m 0.426 ? 0.016 GeV/c2
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Measurement of
(CDF)
The observation of a significant signal (7?) of
the decay
Allows for the measurement of this branching
ratio. To minimize systematic errors the
measurement of a ratio is being reported
Pt(proton)gt2 GeV/c Pt(? from ?b) gt 2
GeV/c Pt(?c)gt 4.5 GeV/c Pt(?b) gt 7.5 GeV/c c?
(?b) gt 225 microns, c? (?c from ?b) gt -65
microns d0 (?b) lt 85 microns Pt(proton) gt Pt(?
from ?c) ?c mass window of 2.269-2.302
GeV/c2 Vertex quality
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Backgrounds subtracted
B0s 321 ? 22 ? 20 (stat,syst)
Signal fit parameters
?bs 96 ? 13 ? 8 (stat,syst)
Four-prong B meson reflections All other B meson
decays All other ?b decays ?b? ?cK decays True
combinatorial background
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Due to
which has a ?27 uncertainty
Using the PDG value for the fragmentation ratio
of fbaryon/fd 0.304 ? 0.053 one obtains

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One can separate the two charge conjugate states
(above) With de/dx corrections Reflections
decrease by 3 while signal goes down only by 15
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Backups etc
Slides following are either back-up or can be
skipped
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Bs? K?K?
Bd? ????
Bd? K?-
Bd? K-?
Bs? K-?
Bs? K-?
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Bd? ????
Bs? K?K?
Bd? K?-
Bd? K-?
Bs? K-?
Bs? K-?
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Bs? K-?
Bs? K-?
Bs? K?K?
Bd? ????
Bd? K?-
Bd? K-?
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CDF analysis
Based on 113 pb-1 Sample of two oppositely
charged muons, m(??-) 2.5 to 6 GeV/c2 with
oppening angle of less
than 2.25 radians. Pt larger than 1.5 to 3.0
GeV/c depending on specific trigger that
fired ? of muons less than 0.6 (i.e. central
muon detectors) Analysis requirements of Ptgt2.0
GeV , and Ptotal(??-) gt6 GeV, at least 3 hits in
the Si detector ?2lt15 and vertex uncertainty of
150 microns Lxy less than 1 cm and c? lt 3
mm Surving events 1954, expected s/n is
1150 Discriminating variables are m(??-) ,
c? , ?? , isolation ?? pointing consistency
(angle between sec. vertex vector and B momentum
vertex) isolation is
, within ?Rlt1 of muon pair
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