Heavy flavour spectroscopy at LHCb ICHEP2012 36th International Conference for High Energy Physics R. M¨ arki on behalf of the LHCb collaboration Ecole Polytechnique F´ ed´ erale de Lausanne (EPFL) 5 July 2012 1/22 R. M¨ arki Heavy flavour spectroscopy at LHCb
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Heavy flavour spectroscopy at LHCbICHEP2012
36th International Conference for High Energy Physics
R. Marki on behalf of the LHCb collaboration
Ecole Polytechnique Federale de Lausanne (EPFL)
5 July 2012
1/22 R. Marki Heavy flavour spectroscopy at LHCb
Outline
Motivation and status
The LHCb experiment at CERN
Mass measurements of ⇤0b, ⌦
�b , ⌅�b and ⌅0
b
First observation of excited ⇤0b baryons
Observation of excited DsJ mesons
Summary and plans
2/22 R. Marki Heavy flavour spectroscopy at LHCb
Motivations for heavy quark hadron spectroscopy
Di↵erent QCD models predict di↵erent masses, lifetimes,branching ratios, spin-parity etc. for many c- and b-hadrons.
Further confirmation and testing of models of the heavy quarkinteractions is provided by c- and b-hadron spectroscopy
b-baryon status: 16 predicted ground states
Weakly decaying: ⇤0b, ⌅
0b ,
⌅�b and ⌦�b baryons observed
Strongly decaying: only charged⌃±b observed
Some first excited states seen
c-meson status:
Remaining puzzles incs states
3/22 R. Marki Heavy flavour spectroscopy at LHCb
The LHCb experiment at CERN
LHCb - single-arm forward spectrometer at the LHC
Recording pp collisions withp
s = 7 TeV (in 2011) and 8 TeV (in 2012)
Optimized for measurements in heavy-flavour physics
Comprizes tracking detectors, RICH detectors, calorimeters and muon chambers.
The tracking system: Vertex Locator (VeLo), Tracker Turicensis (TT),Inner-Tracker (IT) and Outer Tracker (OT)
All compatible with previous results from the B-factories, D⇤sJ(2860)+ confirmed
Precision dominated by systematic e↵ects
No statistically significant DsJ resonance above 3 GeV/c2 observed
Spin-parity assignment still need angular analysis of D⇤K
8LHCb-PAPER-2012-016
16/22 R. Marki Heavy flavour spectroscopy at LHCb
Summary and plans
LHCb gives most precise ⇤0b mass measurement
⌅�b and ⌦�b masses measured at LHCb and CDF observationof ⌦�b confirmed
Excited ⇤0b state observed and measured for the first time at
LHCb
LHCb confirms existence of D⇤sJ(2860)+ and D⇤
s1(2700)+,mass + decay width measured
New measurements are soon to come with 2011 data (1 fb�1):⇤0
b, ⌅�b and ⌦�b lifetimes
Excellent prospects for further spectroscopy at LHCb in theyears to come: expect 2.5 fb�1 by end of 2012 + additional5 fb�1 at least by 2017 with a b-hadron production crosssection twice as large.
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Thank you for your attention
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BACKUP SLIDES
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⌅�b and ⌦�
b mass measurements
Theory, CDF and LHCb agree but DØ does not.
Measurements and prediction still have large uncertainties.
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M(⇡+⇡�) spectrum in ⇤0⇤b ! ⇤0
b⇡+⇡�
)2c) (MeV/!"
+"(M
280 290 300
)2c
Can
did
ates
/ (
2.5
MeV
/
0
2
4
6
8
10
12
14
16
LHCb
M(⇡+⇡�) spectrum is consistent with the result ofphase-space decay simulation (�2/ndf = 1.6 for ndf = 9)
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DsJ states observations
]2 invariant mass [GeV/c0SK+D
2.5 3
2C
andi
date
s / 5
MeV
/c
0
2000
4000
6000(a)LHCb
]2 invariant mass [GeV/c+K0D2.5 3
2C
andi
date
s / 5
MeV
/c
0
20000
40000
(b)LHCb
D+K 0S and D0K+ mass distributions without background
subtraction
The low signal-to-background ratio is responsible for the largesystematic uncertainties