08/09/20 07 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 1 International Symposium of International Symposium of Multiparticle Dynamics 2007 Multiparticle Dynamics 2007 09 Aug 2007 Tania Moulik (University of Kansas) On behalf of CDF & DØ collaboration
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08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 1
International Symposium of Multiparticle International Symposium of Multiparticle Dynamics 2007Dynamics 2007
09 Aug 2007
Tania Moulik (University of Kansas)On behalf of CDF & DØ
collaboration
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 2
Protons :LINAC Booster Main Injector Tevatron 400 MeV 8 GeV 150 GeV ~1.00 TeV
Antiprotons :120 GeV protons (MI) Ni Target antiprotons debuncher+accumulator+recycler Tevatron
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 3
Overview of DetectorsOverview of DetectorsOverview of DetectorsOverview of Detectors
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 4
QCD simplifies in the limit of one heavy quark mass Heavy Quark effective field theory (HQET). Mass scale for heavy baryons different from quark confinement scale ~ 400 MeV governing physics of light hadrons. mt, mb, mc >> QCD >> ms, mu, md
Heavy baryons good way to study non-perturbative QCD (Quark interactions inside hadrons described by non-perturbative QCD)HQET successful in describing Qq systems. Continue to test it for Qqq systems. Features of HQET: Treat heavy quark as static source of color field. In case of baryons, view Light quarks forming a diquark pair and independent
of the heavy quark in the limit of infinite heavy quark mass and it looks the same for any flavor or spin orientation of the heavy quark
Also test Heavy baryon predictions from other theoretical models (approximations to QCD): 1/Nc expansion, sum rules, lattice QCD
B spectroscopy Motivation B spectroscopy Motivation B spectroscopy Motivation B spectroscopy Motivation
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 5
Experimental timeline of heavy B baryonsExperimental timeline of heavy B baryonsExperimental timeline of heavy B baryonsExperimental timeline of heavy B baryons
For a long time only known heavy B baryon was b. Semileptonic decays observed at LEP between 1992-1998 and also at
Tevatron. Hadronic decay modes (Fully reconstructed == Measure mass precisely)
(J/ ) (1991)@UA1 (1997)@CDF c (2006) @ CDF and continued to be studied at
Tevatron.
Recent discoveries at Tevatron of b and b, and the excited B states lead to an exciting new era of testing theories describing quark systems with a heavy baryon. Potential to discover other new B baryons, …and so on…b
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 6
The quest for b BaryonsThe quest for b BaryonsThe quest for b BaryonsThe quest for b Baryons
Light diquark system : spin 0 () (I=0, Jp=0-) / spin 1 () (I=1, Jp=1+) state
state (0+) heavy Quark (1/2+), state (1+) heavy Quark (1/2+)
)23(* Pb J
Host of hadron discoveries led Enrico Fermi to exclaim "Had I foreseen that, I would have gone into botany"
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 7
Mass predictions and hierarchiesMass predictions and hierarchiesMass predictions and hierarchiesMass predictions and hierarchiesWhy are and masses different?
uus – (uds) mass difference believed to be due to difference between u-d and u-s hyperfine interactions :
And other predictions :
hypIE
i ji
ji
ii v
mmmM
Hyperfine splittings
Zeldovich, Sakharov, Sov. J. Nucl. Phys. 4(1967) 283
51.2
*
*
KK
BB
MMMM
MMMM
MM
MMbb
MeVMMbb
194
MeV
MeV
MeV
1.117.6068)(
0.92.5824)(
1.87.5805)(
b
b
b
M
M
M Predicted mass hierarchy:
M(Λb)< M(b) < M(b)
Karliner, Lipkin, hep-ph/0307243, Phys. Lett. B 575, 249(2003)
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 8
Observation of Observation of bbObservation of Observation of bb
Inb light quarks in symmetric state
Together with heavy quark leads to doublet of baryons
Ground state decays strongly to-type baryons (antisymmetric configuration of quarks) emitting pions. Look for b in decay mode b . Number of theoretical predictions:
)(),(,1,1 ddbuubJI bbPl
)(2
3)(
2
1 *b
Pb
P JandJ
180 – 210 MeV
10-40 MeV (Mass splitting)
5-7 MeV
0.400.07 MeV (Isospin splitting)
)()( 0bb mm
)()( *bb mm
)()( bb mm
)()()()( ** bbbb mmmm
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 9
b b bb , , bb cc , , cc p p
K K b b bb , , bb cc , , cc p p
K K Start with constructing b Then, Search for narrow
resonances in the mass difference distribution
Backgrounds: tracks from b fragmentation
(e.g. hadronization of the b quark) and underlying event.
Physics background, B0 D-+; D- -K+- Also B0’s from B**
decays.
Optimize cuts with b signal region blinded.
b cPDG = 422 m, Cut requirement:
c (b) > 250 m
5.565 < m(b) < 5.670 GeV
mmmQ bb )()( 00
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 10
bb Results Resultsbb Results Results
Fit to breit-wigner convoluted with double gaussian. Width of breit-wigner :
No isospin splitting sensitivity
Measure average
22
6
1
pfM
Mp
q
q
qq
)()()()( ** bbbb mmmm
)()( *bb mm
)( bm
)()( *bb mm .)(.)(2.21 4.0
3.00.29.1 syststat
.)(7.1.)(8.5807 0.29.1 syststat
)( bm .)(7.1.)(0.12.5815 syststat
)( *bm
)( *bm
.)(7.1.)(0.5829 6.18.1 syststat
.)(7.1.)(0.20.5836 syststat
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 11
Observation of Observation of b b (dsb)(dsb)Observation of Observation of b b (dsb)(dsb)
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 14
Observation BObservation B11 and B and B22**Observation BObservation B11 and B and B22**
Among B mesons, Only ground 0- states
B+,B0,Bs,Bc and excited 1- state B*
considered established.Quark models predict 2 broad and 2 narrow P-states:
Broad states difficult to distinguish Width ~ 100 MeV (Decay through an S wave).
Narrow states easier to identify Width ~ 10 MeV
(Decay through D wave)
)1(),0( *1
*0
PP JBJB
)2(),1( *21
PP JBJB
2
12
1
LJ
JJ
l
l
M..Di Pierro and E. Eichten, Phys. Rev. D 64 (2001)
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 15
Observation BObservation B11 and B and B22**Observation BObservation B11 and B and B22**
Look for mesons in decay modesReconstruct
BB
BBBB
BBBB
*2
***2
**1
;
; KJB
.)(29320915
36.5)(19.5
stat
GeVBM
Look for track from primary vertex. Combine with B+Plot
)()( BMBMM
),,()1(),,().1(),,(.)(
)()()(
2322221111
MDfMDffMDfNMF
MFMFMF
sig
bkgsig
),()( 0)2(
5
0
00 kkF
k
k
x
xx
Breit-wigner convoluted with gaussian. Resolution in M determined fromsimulation
MeV35.078.45
PDG, J. Phys. G 33 1 (2006)
)(
)(),(
32
*23
*11
E
BBMBBM
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 16
Observation BObservation B11 and B and B22**Observation BObservation B11 and B and B22**
D0 CDF
M(B1) (MeV) 5720.62.4 1.4
M(B2*) (MeV) 5746.82.4 1.7
Unable to resolve the B2* decaying through B* and emission of and through B.
Masses agree to within 1
8.01.1
6.11.2 .)(3.5725
stat
5.06.0
7.18.1 .)(9.5739
stat
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 17
Observation of BObservation of Bss**Observation of BObservation of Bss**
Analysis similar to previous modeLook for the decay
KBBs*2
B*s2B+K-
Where is B*s2B* K ? should be
here MeVKMBMBM s 20)()()( **2
Claim : Suppressed due to L=2 orbital angular momentum and small mass difference
D0 does not observe the Bs1 peak. Would be interesting to look at more data.
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 18
BBss* Interpretation and Theory* Interpretation and TheoryBBss* Interpretation and Theory* Interpretation and Theory
Theory predicts equal branching ratios of Bs2* B*+K- and B+K-. Experimentally should be observed as resonance displaced to lower M by photon energy 45.78+-0.35 MeV.Rate supressed by a factor (No signal expected with current statistics)
What about Bs1 B*K+? In (bd) system, M(B2*) – M(B1) = 26.2+-3.1+-0.9, ..Applying to Bs
system… Expect Bs1 = 5813 MeV i.e. < M(B*)+M(K-) (5819 MeV)…In this case,
no Bs1 signal expected.
C.M. Momentum of K in B*K decay
C.M. momentum of K in B K decay
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 19
Results BResults Bss**Results BResults Bss**
MeVstat
statN
MeVsyststatBM
MeVsyststatKMBMBM
s
s
.)(5.17.4
.)(31135
)(6.1)(4.11.5839)(
)(5.1)(3.14.66)()()(*2
*2
.)(0.94.36)(
)(6.0)(14.0)(21.041.5829)(
)(14.0)(21.073.10)()()(
.)(4.238.94)(
)(5.0)(14.0)(39.05839)(
)(14.0)(34.096.66)()()(
1
1
*1
*2
*2
*2
statBN
MeVPDGsyststatBM
MeVsyststatKMBMBM
statBN
MeVPDGsyststatBM
MeVsyststatKMBMBM
s
s
s
s
s
s
10.1 fbdtL
10.1 fbdtL
08/09/2007 Tania Moulik, B Spectroscopy at Tevatron, ISMD 2007 20
B Quest began … and continues @ FermilabB Quest began … and continues @ FermilabB Quest began … and continues @ FermilabB Quest began … and continues @ Fermilab
Celebrating 30 years of the b quark discovery @ Fermilab
A fitting anniversary celebration: Discovery of new B baryons…and the search goes on…!