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Spectroscopy highlights from Run I and II at LHCband outlook for the upgrade
Marian StahlPhysikalisches Institut, Heidelberg University
Implications of LHCb measurements and future prospectsOctober 16th, 2018
gMot
ivatio
n
1 / 15
]2 cM
ass
[GeV
/
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
0(3000)cΩ
0(3050)cΩ0(3066)cΩ0(3090)cΩ0(3119)cΩ
cΩ*cΩ
(2S)cΩ*(2S)cΩ
0cΩ1cΩ 1cΩ 2cΩ
2cΩ
(2P)0cΩ (2P)1cΩ(2P)1cΩ (2P)2cΩ
(2P)2cΩ
(1D)1cΩ (1D)1cΩ (1D)2cΩ(1D)2cΩ (1D)3cΩ
(1D)3cΩ
L
qq'j
PJ
S1
+
21
S1
+
23
P0
-
21
P1-
21
P1-
23
P2
-
23
P2
-
25
D1+
21
D1+
23
D2+
23
D2+
25
D3+
25
D3+
27
[PRL 118 182001 (sup)]
[CERN-THESIS-2018-176]
Hadron spectroscopy(Experiment)
“Bread and butter” aspect:input/background for many SM/NPmeasurements like γ, LFU tests ...
QCD Phenomenology Interpretations
m,ΓJP , B· · ·
expected spectrumformalisms . . .
vs.
Greater challenge: link QCD’s pure Yang-Mills sector to observationsHadronic spectrum is the prime observable of QCD
gHad
ron
spec
trosc
opy
atLH
Cb
2 / 15
PV
~pXb
(p/K+)
π+
K−flight di
stance
π−IPπ−
Xb decay vertexXc decay vertex
3 Excellent mass-, momentum-, vertex- and decay time resolutionHighly efficient track reconstruction at low fake rate down to low pTFast and efficient topological selection of b and c decays
3 Excellent particle identificationHigh purity hadronic final states
3 Flexible, offline quality software trigger3 Huge samples of b and c hadrons
All types of hadrons are produced, incl. b baryons and excited statesLHCb is a b baryon factory! ≈ 2M (180k) reco’d and selected Λ0
b → Λ+c µ
−νµ (Λ0
b → Λ+c π
−) per fb−1 @ 13 TeV
Large samples of exclusive decays foramplitude analyses
3 Upgrade: no hardware trigger, resolutions improve,instantaneous luminosity increases
LHCb has unique potential for spectroscopy
[CERN-THESIS-2018-176]
[LHCb-PUB-2018-009]
gD0→
K∓
π±
π±
π∓
ampl
itude
anal
ysis
3 / 15
D0 → K∓π±π±π∓ amplitudes input to γ and charm mixing measurementsSpectroscopy: light hadronic spectrum crucial for modelling non-perturbative QCDChallenges: broad states, interference, threshold effects, model complexityDouble tag method: B0 → D∗+µ−νµ with D∗+ → D0π+. Still a huge sample!
140 145 150∆m [ MeV/c2]
0
20
40
60
80
100
120
140
160×103
Can
did
ates/
(0.1
2M
eV/c
2)
LHCb
RS data
D0→K−π+π+π−
Combinatorial
140 145 150∆m [ MeV/c2]
0
100
200
300
400
500
600
Can
did
ates/
(0.1
2M
eV/c
2)
LHCb
WS data
D0→K+π−π−π+
CombinatorialMistag
Cabibbo favoured
Nsig ≈ 890k
Doubly Cabibbosuppressed
Nsig ≈ 3030
[EPJC 78 (2018) 443]
gD0→
K∓
π±
π±
π∓
ampl
itude
anal
ysis
4 / 15
Resonance structure dominated by axial resonances; fit fraction ofD0 → K0(1460)−π+ ≈ 4% with K0(1460)− → K−π+π−
Spectroscopic highlight: quasi model independent partial wave analysis (QMIPWA)of the kaons first radial excitation K0(1460)−
1 2 3sK−π+π−
[GeV2/c4
]0246810121416182022
×103
Entries/
(0.03GeV
2 /c4)
LHCb
0 0.5 1Re (A)
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Im(A
)
m = 1.14 GeV/c2
m = 1.64 GeV/c2
LHCb
Citation: M. Tanabashi et al. (Particle Data Group), Phys. Rev. D 98, 030001 (2018)
K (1460) I (JP ) = 12 (0
−)
OMITTED FROM SUMMARY TABLEObserved in K ππ partial-wave analysis.
K (1460) MASSK (1460) MASSK (1460) MASSK (1460) MASS
VALUE (MeV) DOCUMENT ID TECN CHG COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •∼ 1460 DAUM 81C CNTR − 63 K− p → K− 2πp
∼ 1400 1 BRANDENB... 76B ASPK ± 13 K± p → K+2πp
1Coupled mainly to K f0(1370). Decay into K∗(892)π seen.
K (1460) WIDTHK (1460) WIDTHK (1460) WIDTHK (1460) WIDTH
VALUE (MeV) DOCUMENT ID TECN CHG COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •∼ 260 DAUM 81C CNTR − 63 K− p → K− 2πp
∼ 250 2 BRANDENB... 76B ASPK ± 13 K± p → K+2πp
2Coupled mainly to K f0(1370). Decay into K∗(892)π seen.
K (1460) DECAY MODESK (1460) DECAY MODESK (1460) DECAY MODESK (1460) DECAY MODES
Mode Fraction (Γi /Γ)
Γ1 K∗(892)π seen
Γ2 K ρ seen
Γ3 K∗0(1430)π seen
K (1460) PARTIAL WIDTHSK (1460) PARTIAL WIDTHSK (1460) PARTIAL WIDTHSK (1460) PARTIAL WIDTHS
Γ(K∗(892)π
)Γ1Γ
(K∗(892)π
)Γ1Γ
(K∗(892)π
)Γ1Γ
(K∗(892)π
)Γ1
VALUE (MeV) DOCUMENT ID TECN COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •∼ 109 DAUM 81C CNTR 63 K− p → K− 2πp
Γ(K ρ
)Γ2Γ
(K ρ
)Γ2Γ
(K ρ
)Γ2Γ
(K ρ
)Γ2
VALUE (MeV) DOCUMENT ID TECN COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •∼ 34 DAUM 81C CNTR 63 K− p → K− 2πp
Γ(K∗
0(1430)π)
Γ3Γ(K∗
0(1430)π)
Γ3Γ(K∗
0(1430)π)
Γ3Γ(K∗
0(1430)π)
Γ3VALUE (MeV) DOCUMENT ID TECN COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •∼ 117 DAUM 81C CNTR 63 K− p → K− 2πp
HTTP://PDG.LBL.GOV Page 1 Created: 6/5/2018 18:59
Table 4: Table of fit fractions and coupling parameters for the component involving theK1(1270)−
meson, from the fit performed on the RS decay D0 → K−π+π+π−. The coupling parametersare defined with respect to the K1(1270)
− → ρ(770)0K− coupling. For each parameter, the firstuncertainty is statistical and the second systematic.
K1(1270)− m0 = 1289.81± 0.56± 1.66MeV/c2; Γ0 = 116.11± 1.65± 2.96MeV/c2
Partial Fractions [%] |g| arg(g)[o]
ρ(770)0K− 96.30± 1.64± 6.61ρ(1450)0K− 49.09± 1.58± 11.54 2.016± 0.026± 0.211 −119.5± 0.9± 2.3K∗(892)0π− 27.08± 0.64± 2.82 0.388± 0.007± 0.033 −172.6± 1.1± 6.0
[K−π+]L=0
π− 22.90± 0.72± 1.89 0.554± 0.010± 0.037 53.2± 1.1± 1.9[K∗(892)0π−]L=2
3.47± 0.17± 0.31 0.769± 0.021± 0.048 −19.3± 1.6± 6.7ω(782) [π+π−]K− 1.65± 0.11± 0.16 0.146± 0.005± 0.009 9.0± 2.1± 5.7
Table 5: Table of fit fractions and coupling parameters for the component involving the K(1460)−
meson, from the fit performed on the RS decay D0 → K−π+π+π−. The coupling parametersare defined with respect to the K(1460)− → K∗(892)0π− coupling. For each parameter, the firstuncertainty is statistical and the second systematic.
K(1460)− m0 = 1482.40± 3.58± 15.22MeV/c2 ; Γ0 = 335.60± 6.20± 8.65MeV/c2
Partial Fractions [%] |g| arg(g)[o]
K∗(892)0π− 51.39± 1.00± 1.71
[π+π−]L=0K− 31.23± 0.83± 1.78
fKK 1.819± 0.059± 0.189 −80.8± 2.2± 6.6β1 0.813± 0.032± 0.136 112.9± 2.6± 9.5β0 0.315± 0.010± 0.022 46.7± 1.9± 3.0
18
[EPJC 78 (2018) 443]
Great potential to study light spectrum at LHCb
gDsJ
stat
es(in
clusiv
e)
5 / 15
]2 invariant mass [GeV/c0SK+D
2.5 3
2C
and
idat
es /
5 M
eV/c
0
2000
4000
6000(a)LHCb
[MeV])S
0K*+m(D
2600 2800 3000 3200 3400
Can
dida
tes
/ (8
MeV
)
0
5000
10000
15000
20000 LHCb
2600 2800 3000 3200 3400
0
500
]2 invariant mass [GeV/c0SK+D
2.5 3
2C
and
idat
es /
5 M
eV/c
0
200
400 (c)LHCb
Open charm spectroscopy probes perturbative – non-perturbative transition region;static heavy quarks (HQET) vs. dynamical resonance generationMuch discussed example: D∗sJ(2860)
Observed in inclusive reactions in the DK and D∗K channels atBaBar [PRL 97 222001],[PRD 80 092003] and LHCb [JHEP10(2012)151],[JHEP02(2016)133] respectivelyAssignment as 13D3 state preferred, but large D∗K rate measured at BaBar is puzzling[Rept.Prog.Phys. 80 076201]
gDsJ
stat
es(e
xclu
sive)
6 / 15
D∗sJ(2860)− puzzle (momentarily) solved by B0s → D0K−π+ amplitude analysis
Resolved D∗sJ (2860)− into D∗
s1(2860)− (JP = 1−) and D∗s3(2860)− (JP = 3−)
Favoured assignments Ds(13D1) and Ds(13D3)
Do Ds(13D1) and Ds(23S1) states mix to form D∗s1(2860)− and D∗
s1(2700)−?
Amplitude analysis in D∗K channel (e.g. B0s → D∗−K 0
Sπ+) and measurement
of decay rates relative to DK sensitive to mixing parameters
)−K0
D(θcos -1 -0.5 0 0.5 1
Can
dida
tes
/ 0.0
4
0
10
20
30
40
50 LHCbData
spin-1 + spin-3
spin-1
spin-3
requirements lead to a maximum efficiency variation of
about 20%, while other effects are smaller.
Projections of the data and the unbinned maximum
likelihood fit result are shown in Fig. 3. The largest
components in terms of their fit fractions, defined as the
ratio of the integrals over the Dalitz plot of a single decay
amplitude squared and the total amplitude squared, are the
Kð892Þ0 (28.6%), Ds2ð2573Þ
− (25.7%), LASS (21.4%),
and D0K− nonresonant (12.4%) terms. The fit fractions for
the Ds1ð2860Þ
− and Ds3ð2860Þ
− components are ð5.01.2 0.7 3.3Þ% and ð2.2 0.1 0.3 0.4Þ%, respec-
tively, where the uncertainties are statistical, systematic,
and from Dalitz plot model variations, as described
below. The phase difference between the Ds1ð2860Þ
−
and Ds3ð2860Þ
− amplitudes is consistent with π within a
large model uncertainty.
To assess the significance of the two states near
mðD0K−Þ ≈ 2860 MeV=c2, the fit is repeated with all
combinations of either one or two resonant amplitudes
with different spins up to and including 3. All other
combinations give values of negative log-likelihood more
than one hundred units larger than the default fit. A
comparison of the angular distributions in the region near
mðD0K−Þ ≈ 2860 MeV=c2 of the data and the best fits
with the spin-1 only, spin-3 only, and both resonances is
presented in Fig. 4. Including both spin components visibly
improves the fit. Large samples of pseudoexperiments
are generated with signal models corresponding to the best
fits with the spin-1 or spin-3 amplitude removed, and each
pseudoexperiment is fitted under both the one- and two-
resonance hypotheses. By extrapolating the tails of the
distributions of the difference in negative log-likelihood
values to the values observed in data, the statistical sig-
nificances of the spin-3 and spin-1 components are found
to be 16 and 15 standard deviations, respectively. These
significances remain in excess of 10 standard deviations in
all alternative models considered below.
The considered sources of systematic uncertainty are
divided into two main categories: experimental uncertain-
ties and model uncertainties. The experimental systematic
uncertainties arise from imperfect knowledge of: the
relative amount of signal and background in the selected
events; the distributions of each of the backgrounds across
the phase space; the variation of the efficiency across the
phase space; the possible bias induced by the fit procedure;
the momentum calibration; the fixed masses of the B0s and
D0 mesons used to define the boundaries of the Dalitz plot.
Model uncertainties occur due to: fixed parameters in the
Dalitz plot model; the treatment of marginal components in
the default fit model; the choice of models for the K−πþ S
wave, the D0K− S and P waves, and the line shapes of the
virtual resonances. The systematic uncertainties from each
source are combined in quadrature.
The masses and widths of the Ds2ð2573Þ
−, Ds1ð2860Þ
−,
and Ds3ð2860Þ
− states are determined to be
m(Ds2ð2573Þ
−)¼ 2568.39 0.29 0.19 0.18MeV=c2;
Γ(Ds2ð2573Þ
−)¼ 16.9 0.5 0.4 0.4MeV=c2;
m(Ds1ð2860Þ
−)¼ 2859 12 6 23MeV=c2;
Γ(Ds1ð2860Þ
−)¼ 159 23 27 72MeV=c2;
m(Ds3ð2860Þ
−)¼ 2860.5 2.6 2.5 6.0MeV=c2;
Γ(Ds3ð2860Þ
−)¼ 53 7 4 6MeV=c2;
where the first uncertainty is statistical, the second is due
to experimental systematic effects, and the third is due to
model variations. The largest sources of uncertainty on the
parameters of the Ds1ð2860Þ
− and Ds3ð2860Þ
− resonances
arise from varying the K−πþ S-wave description and, for
the Ds1ð2860Þ
− width, from removing the Kð1680Þ0 and
Bþv components from the model. The results for the
Ds2ð2573Þ
− mass and width are determined with signifi-
cantly better precision than previous measurements. Those
for the parameters of the Ds1ð2860Þ
− and Ds3ð2860Þ
−
resonances must be considered first measurements, since
previous measurements of the properties of theDsJð2860Þ
−
state [3,5,6] involved an unknown admixture of at least
these two particles. The results for all the complex
amplitudes determined by the Dalitz plot fit, as well as
derived quantities such as branching fractions of the
resonant contributions and detailed descriptions of the
systematic uncertainties, are given in Ref. [17].
In summary, results of the first amplitude analysis of
the B0s → D0K−πþ decay show, with significance of
more than 10 standard deviations, that a structure at
FIG. 4 (color online). Projections of the data and Dalitz plot fit
results with alternative models onto the cosine of the helicity
angle of the D0K− system, cos θðD0K−Þ, for 2.77 < mðD0K−Þ <2.91 GeV=c2, where θðD0K−Þ is the angle between the πþ and
the D0 meson momenta in the D0K− rest frame. The data are
shown as black points, with the fit results with different models as
detailed in the legend. The dip at cos θðD0K−Þ ≈ −0.6 is due to
the D0 veto. Comparisons of the data and the different fit results
in the 50 bins of this projection give χ2 values of 47.3, 214.0,
and 150.0 for the default, spin-1 only, and spin-3 only models,
respectively.
PRL 113, 162001 (2014) P HY S I CA L R EV I EW LE T T ER Sweek ending
17 OCTOBER 2014
162001-4
[PRL 113 162001] [PRD 90 072003]
Reached precision era of single open charm spectroscopy
gD0 p
ampl
itude
inΛ0 b→
D0 p
π−
7 / 15
First amplitude analysis involving open charm baryonsIs the Λc(2940)+ a D∗N molecule? ⇒ Measure JP
Kinematic separation of pπ− and D0p resonances ⇒ analyse only D0p amplitudesNear threshold region can only be described by adding new Λc(2860)+ resonance
+(2880)cΛ
+(2940)cΛ
)+(1/2p
0D
NR
)−
(1/2p
0D
NR
)−
(3/2p
0D
NR
+(2860)cΛ
)+(1/2−πpNR
Background
]2
) [GeVp0
D(2
M
10 20 30
]2
) [G
eV
−
πp(
2M
0
2
4
6
8
10
12
144
1
LHCb
) [GeV]p0
D(M
2.8 2.85 2.9 2.95 3C
an
did
ate
s /
(0.0
04
GeV
)0
50
100
150
200
250
300
LHCb
[JHEP05(2017)030]
First observation of Λc (2860)+
gD0 p
ampl
itude
inΛ0 b→
D0 p
π−
8 / 15
JHEP05(2017)030
of the Λc(2880)+ state are found to be:
m(Λc(2880)+) = 2881.75± 0.29(stat)± 0.07(syst)+0.14
−0.20(model)MeV,
Γ(Λc(2880)+) = 5.43+0.77
−0.71(stat)± 0.29(syst)+0.75−0.00(model)MeV.
These results are consistent with and have comparable precision to the current world av-
erages (WA), which are mWA(Λc(2880)+) = 2881.53 ± 0.35MeV, and ΓWA(Λc(2880)
+) =
5.8± 1.1MeV [23].
A near-threshold enhancement in the D0p amplitude is studied. The enhancement
is consistent with being a resonant state (referred to here as the Λc(2860)+) with mass
and width
m(Λc(2860)+) = 2856.1+2.0
−1.7(stat)± 0.5(syst)+1.1−5.6(model)MeV,
Γ(Λc(2860)+) = 67.6+10.1
−8.1 (stat)± 1.4(syst)+5.9−20.0(model)MeV
and quantum numbers JP = 3/2+, with the parity measured relative to that of the
Λc(2880)+ state. The other quantum numbers are excluded with a significance of more
than 6 standard deviations. The phase motion of the 3/2+ component with respect to
the nonresonant amplitudes is obtained in a model-independent way and is consistent with
resonant behaviour. With a larger dataset, it should be possible to constrain the phase
motion of the 3/2+ partial wave using the Λc(2880)+ amplitude as a reference, without
making assumptions on the nonresonant amplitude behaviour. The mass of the Λc(2860)+
state is consistent with recent predictions for an orbital D-wave Λ+c excitation with quan-
tum numbers 3/2+ based on the nonrelativistic heavy quark-light diquark model [24] and
from QCD sum rules in the HQET framework [26].
First constraints on the spin and parity of the Λc(2940)+ state are obtained in this
analysis, and its mass and width are measured. The most likely spin-parity assignment for
Λc(2940)+ is JP = 3/2− but the other solutions with spins 1/2 to 7/2 cannot be excluded.
The mass and width of the Λc(2940)+ state are measured to be
m(Λc(2940)+) = 2944.8+3.5
−2.5(stat)± 0.4(syst)+0.1−4.6(model)MeV,
Γ(Λc(2940)+) = 27.7+8.2
−6.0(stat)± 0.9(syst)+5.2−10.4(model)MeV.
The JP = 3/2− assignment for Λc(2940)+ state is consistent with its interpretations as a
D∗N molecule [16, 17, 19] or a radial 2P excitation [21].
Acknowledgments
We express our gratitude to our colleagues in the CERN accelerator departments for
the excellent performance of the LHC. We thank the technical and administrative staff
at the LHCb institutes. We acknowledge support from CERN and from the national
agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3
(France); BMBF, DFG and MPG (Germany); INFN (Italy); FOM and NWO (The Nether-
lands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FASO (Russia);
– 33 –
JHEP05(2017)030
of the Λc(2880)+ state are found to be:
m(Λc(2880)+) = 2881.75± 0.29(stat)± 0.07(syst)+0.14
−0.20(model)MeV,
Γ(Λc(2880)+) = 5.43+0.77
−0.71(stat)± 0.29(syst)+0.75−0.00(model)MeV.
These results are consistent with and have comparable precision to the current world av-
erages (WA), which are mWA(Λc(2880)+) = 2881.53 ± 0.35MeV, and ΓWA(Λc(2880)
+) =
5.8± 1.1MeV [23].
A near-threshold enhancement in the D0p amplitude is studied. The enhancement
is consistent with being a resonant state (referred to here as the Λc(2860)+) with mass
and width
m(Λc(2860)+) = 2856.1+2.0
−1.7(stat)± 0.5(syst)+1.1−5.6(model)MeV,
Γ(Λc(2860)+) = 67.6+10.1
−8.1 (stat)± 1.4(syst)+5.9−20.0(model)MeV
and quantum numbers JP = 3/2+, with the parity measured relative to that of the
Λc(2880)+ state. The other quantum numbers are excluded with a significance of more
than 6 standard deviations. The phase motion of the 3/2+ component with respect to
the nonresonant amplitudes is obtained in a model-independent way and is consistent with
resonant behaviour. With a larger dataset, it should be possible to constrain the phase
motion of the 3/2+ partial wave using the Λc(2880)+ amplitude as a reference, without
making assumptions on the nonresonant amplitude behaviour. The mass of the Λc(2860)+
state is consistent with recent predictions for an orbital D-wave Λ+c excitation with quan-
tum numbers 3/2+ based on the nonrelativistic heavy quark-light diquark model [24] and
from QCD sum rules in the HQET framework [26].
First constraints on the spin and parity of the Λc(2940)+ state are obtained in this
analysis, and its mass and width are measured. The most likely spin-parity assignment for
Λc(2940)+ is JP = 3/2− but the other solutions with spins 1/2 to 7/2 cannot be excluded.
The mass and width of the Λc(2940)+ state are measured to be
m(Λc(2940)+) = 2944.8+3.5
−2.5(stat)± 0.4(syst)+0.1−4.6(model)MeV,
Γ(Λc(2940)+) = 27.7+8.2
−6.0(stat)± 0.9(syst)+5.2−10.4(model)MeV.
The JP = 3/2− assignment for Λc(2940)+ state is consistent with its interpretations as a
D∗N molecule [16, 17, 19] or a radial 2P excitation [21].
Acknowledgments
We express our gratitude to our colleagues in the CERN accelerator departments for
the excellent performance of the LHC. We thank the technical and administrative staff
at the LHCb institutes. We acknowledge support from CERN and from the national
agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3
(France); BMBF, DFG and MPG (Germany); INFN (Italy); FOM and NWO (The Nether-
lands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FASO (Russia);
– 33 –
JHEP05(2017)030
of the Λc(2880)+ state are found to be:
m(Λc(2880)+) = 2881.75± 0.29(stat)± 0.07(syst)+0.14
−0.20(model)MeV,
Γ(Λc(2880)+) = 5.43+0.77
−0.71(stat)± 0.29(syst)+0.75−0.00(model)MeV.
These results are consistent with and have comparable precision to the current world av-
erages (WA), which are mWA(Λc(2880)+) = 2881.53 ± 0.35MeV, and ΓWA(Λc(2880)
+) =
5.8± 1.1MeV [23].
A near-threshold enhancement in the D0p amplitude is studied. The enhancement
is consistent with being a resonant state (referred to here as the Λc(2860)+) with mass
and width
m(Λc(2860)+) = 2856.1+2.0
−1.7(stat)± 0.5(syst)+1.1−5.6(model)MeV,
Γ(Λc(2860)+) = 67.6+10.1
−8.1 (stat)± 1.4(syst)+5.9−20.0(model)MeV
and quantum numbers JP = 3/2+, with the parity measured relative to that of the
Λc(2880)+ state. The other quantum numbers are excluded with a significance of more
than 6 standard deviations. The phase motion of the 3/2+ component with respect to
the nonresonant amplitudes is obtained in a model-independent way and is consistent with
resonant behaviour. With a larger dataset, it should be possible to constrain the phase
motion of the 3/2+ partial wave using the Λc(2880)+ amplitude as a reference, without
making assumptions on the nonresonant amplitude behaviour. The mass of the Λc(2860)+
state is consistent with recent predictions for an orbital D-wave Λ+c excitation with quan-
tum numbers 3/2+ based on the nonrelativistic heavy quark-light diquark model [24] and
from QCD sum rules in the HQET framework [26].
First constraints on the spin and parity of the Λc(2940)+ state are obtained in this
analysis, and its mass and width are measured. The most likely spin-parity assignment for
Λc(2940)+ is JP = 3/2− but the other solutions with spins 1/2 to 7/2 cannot be excluded.
The mass and width of the Λc(2940)+ state are measured to be
m(Λc(2940)+) = 2944.8+3.5
−2.5(stat)± 0.4(syst)+0.1−4.6(model)MeV,
Γ(Λc(2940)+) = 27.7+8.2
−6.0(stat)± 0.9(syst)+5.2−10.4(model)MeV.
The JP = 3/2− assignment for Λc(2940)+ state is consistent with its interpretations as a
D∗N molecule [16, 17, 19] or a radial 2P excitation [21].
Acknowledgments
We express our gratitude to our colleagues in the CERN accelerator departments for
the excellent performance of the LHC. We thank the technical and administrative staff
at the LHCb institutes. We acknowledge support from CERN and from the national
agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3
(France); BMBF, DFG and MPG (Germany); INFN (Italy); FOM and NWO (The Nether-
lands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FASO (Russia);
– 33 –
JHEP05(2017)030
∆ lnL uncertainty for Λc(2940)+ JP
Source No Λc(2940)+ 1/2+ 1/2− 3/2+ 5/2+ 5/2− 7/2+ 7/2−
Background fraction 0.3 0.7 0.3 0.9 0.7 0.6 0.7 0.8
Efficiency profile 0.3 0.2 0.6 0.6 0.6 0.6 0.9 1.1
Background shape 3.6 3.4 3.3 2.6 1.4 2.0 2.4 4.0
Momentum resolution 0.1 0.0 0.1 0.1 0.1 0.1 0.1 0.1
Λc(2880)+ parameters 0.2 0.2 0.9 0.2 0.3 0.1 0.5 0.4
Total systematic 3.6 3.5 3.4 2.8 1.7 2.2 2.6 4.2
Breit-Wigner model 2.1 1.2 1.9 1.6 2.3 0.4 1.4 1.4
Nonresonant model 3.7 2.4 0.4 1.5 1.0 1.9 1.4 0.1
Total model 4.3 2.7 1.9 2.1 2.5 1.9 2.0 1.4
Table 10. Systematic and model uncertainties on ∆ lnL between the baseline fit with JP = 3/2−
for the Λc(2940)+ state and other fits without a Λc(2940)
+ contribution or with other spin-parity
assignments, for the exponential nonresonant model.
∆ lnL uncertainty for Λc(2940)+ JP
Source No Λc(2940)+ 1/2+ 1/2− 3/2+ 5/2+ 5/2− 7/2+ 7/2−
Background fraction 0.6 0.1 0.2 0.3 0.3 0.4 0.1 0.6
Efficiency profile 0.6 0.5 0.5 0.3 0.2 0.6 0.7 0.7
Background shape 1.2 0.5 0.6 1.4 1.6 0.7 1.5 1.3
Momentum resolution 0.5 0.2 0.1 0.1 0.1 0.1 0.1 0.1
Λc(2880)+ parameters 0.2 0.6 0.2 0.2 0.1 0.4 0.3 0.5
Total systematic 1.6 0.9 0.8 1.5 1.6 1.1 1.7 1.7
Breit-Wigner model 1.1 0.7 0.4 0.6 1.1 0.5 0.9 0.3
Nonresonant model 3.7 2.2 2.2 1.6 0.8 1.3 2.1 3.2
Total model 3.8 2.3 2.3 1.7 1.3 1.4 2.3 3.2
Table 11. Systematic and model uncertainties on ∆ lnL between the baseline fit with JP = 3/2−
for the Λc(2940)+ state and other fits without a Λc(2940)
+ contribution or with other spin-parity
assignments, for the polynomial nonresonant model.
The contributions of individual resonant components, integrated over the entire phase
space of the Λ0b→ D0pπ− decay, can be used to extract the ratios of branching fractions
B(Λ0b→ Λc(2860)
+π−)×B(Λc(2860)+ → D0p)
B(Λ0b→ Λc(2880)+π−)×B(Λc(2880)+ → D0p)
= 4.54+0.51−0.39
(stat)± 0.12(syst)+0.17−0.58
(model),
B(Λ0b→ Λc(2940)
+π−)×B(Λc(2940)+ → D0p)
B(Λ0b→ Λc(2880)+π−)×B(Λc(2880)+ → D0p)
= 0.83+0.31−0.10
(stat)± 0.06(syst)+0.17−0.43
(model),
which assumes the ratios of the branching fractions to be equal to the ratios of the fit
fractions.
The constraints on the Λc(2940)+ quantum numbers depend on the description of the
nonresonant amplitudes. If an exponential model is used for the nonresonant components,
the single best spin-parity assignment is JP = 3/2−, and the 3/2+, 5/2+ and 5/2− as-
– 31 –
)+
(3/2RRe
40− 20− 0 20 40
)+
(3/2
RIm
40−
30−
20−
10−
0
10
20
30
40
0
1
23
4
5
LHCb
[JHEP05(2017)030]
Phase motion of Λc(2860)+ [(JP)preferred = 3/2+] resembles Breit-WignerΛc(2860)+ and Λc(2880)+ [(JP)preferred = 5/2+] consistent with D-wave doubletΛc(2940)+ [(JP)preferred = 3/2−] radial 2P excitation or S-wave D∗N molecule?Need to study Σ(∗)
c π channel [arXiv:1803.00364 [hep-ph]][RevModPhys 90 015004]
Precision spectroscopy of charm baryons just begun. Many possibilities ahead
gΩ∗∗0
cst
ates
(inclu
sive
Ξ+ cK−
)
9 / 15
Before: Only ground state Ωc and Ωc(2770)0 known. More Ω∗cs expected
Observed 5 new narrow states + 1 broad (?) in inclusive Ξ+c K− spectrum
Why so many? Why so narrow? Expected only narrow Ωc2 D-wave decays in Ξ+c K−
Narrowness: ss diquark hard to separate? No decays to ΞD (kinematics)[PRD 95 114012]
]2 cM
ass
[GeV
/
2.6
2.7
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
KcΞ
' KcΞ
* KcΞ DΞ
π π 0cΩ
π π *0cΩ
π K cΞ
KK +cΛ
0π 0cΩ
0π *0cΩ
cΩ*cΩ
(2S)cΩ*(2S)cΩ
0cΩ1cΩ 1cΩ 2cΩ
2cΩ
(2P)0cΩ (2P)1cΩ(2P)1cΩ (2P)2cΩ
(2P)2cΩ
(1D)1cΩ (1D)1cΩ (1D)2cΩ(1D)2cΩ (1D)3cΩ
(1D)3cΩ
L
qq'j
PJ
S1
+
21
S1
+
23
P0
-
21
P1-
21
P1-
23
P2
-
23
P2
-
25
D1+
21
D1+
23
D2+
23
D2+
25
D3+
25
D3+
27
) [MeV]−
K+cΞ(m
3000 3100 3200 3300
Can
dida
tes
/ (1
MeV
)
0
100
200
300
400 LHCb−K+
cΞFull fitBackground
Feed-downs sidebands+
cΞ
[PRL 118 182001]
(css)
(cus)(su)
(uss)(cu) or (dss)(cd)
ΞD threshold
gΩ∗∗0
cst
ates
(inclu
sive
Ξ+ cK−
)
10 / 15
Several interpretations,many implications...Study further incl. channels(e.g. Ω0
cγ/π+π−, Ξ0
cK 0S )
Measure JP (incl. or excl., e.g.Ξb → Ω∗∗0c D, Ξ−b /Ω−b → Ω∗∗0c π−)
Resonance Mass ( MeV ) Γ ( MeV ) Yield Nσ
Ωc(3000)0 3000.4 ± 0.2 ± 0.1+0.3−0.5 4.5 ± 0.6 ± 0.3 1300 ± 100 ± 80 20.4
Ωc(3050)0 3050.2 ± 0.1 ± 0.1+0.3−0.5 0.8 ± 0.2 ± 0.1 970 ± 60 ± 20 20.4
< 1.2 MeV, 95% CL
Ωc(3066)0 3065.6 ± 0.1 ± 0.3+0.3−0.5 3.5 ± 0.4 ± 0.2 1740 ± 100 ± 50 23.9
Ωc(3090)0 3090.2 ± 0.3 ± 0.5+0.3−0.5 8.7 ± 1.0 ± 0.8 2000 ± 140 ± 130 21.1
Ωc(3119)0 3119.1 ± 0.3 ± 0.9+0.3−0.5 1.1 ± 0.8 ± 0.4 480 ± 70 ± 30 10.4
< 2.6 MeV, 95% CL
Ωc(3188)0 3188 ± 5 ± 13 60 ± 15 ± 11 1670 ± 450 ± 360
Ωc(3066)0fd 700 ± 40 ± 140
Ωc(3090)0fd 220 ± 60 ± 90
Ωc(3119)0fd 190 ± 70 ± 20
empirical reasons. For instance, it was shown in
Refs. [19,35–41] that the hadronic decays of heavy-light
mesons and baryons can be reasonably described by
treating the light pseudoscalar mesons, i.e., π, K, and η,
as fundamental states in the chiral quark model. Then, the
decay patterns of those low-lying heavy-light mesons and
baryons can be described. The chiral quark model has also
been broadly applied to various processes involving light
pseudoscalar meson productions [42–59]. In this model,
the low energy quark-pseudoscalar-meson interactions in
the SU(3) flavor basis are described by the effective
Lagrangian [45–47]
Hm ¼X
j
1
fmIjψ jγ
jμγ
j5ψ j∂
μϕm; ð1Þ
where ψ j represents the jth quark field in the hadron; ϕm is
the pseudoscalar meson field, fm is the pseudoscalar meson
decay constant, and Ij is the isospin operator associated
with the pseudoscalar meson.
Meanwhile, to treat the radiative decay of a hadron we
apply the constituent quark model which has been success-
fully applied to study the radiative decays of cc and bbsystems [60,61]. In this model, the quark-photon EM
coupling at the tree level is adopted as [62]
He ¼ −
X
j
ejψ jγjμAμðk; rjÞψ j; ð2Þ
where Aμ represents the photon field with three-momentum
k. ej and rj stand for the charge and coordinate of the
constituent quark ψ j, respectively.
To match the nonrelativistic harmonic oscillator wave
functions adopted in our calculations, we should provide
the quark-pseudoscalar and quark-photon EM couplings in
a nonrelativistic form. In the initial-hadron-rest system, the
nonrelativistic form of the quark-photon EM coupling can
be written as [45–47,60–62]
TABLE I. The spectrum of 1P- and 2S-wave Ωc states in the constituent quark model. The total wave function of a Ωc state is
denoted by jN2Sþ1LσJPi. The Clebsch-Gordan series for the spin and angular-momentum addition jN2Sþ1LσJ
Pi ¼P
LzþSz¼JzhLLz; SSzjJJziNΨσ
LLzχSzϕΩc
has been omitted. The details of the wave functions can be found in our previous work
[19]. The unit of mass is MeV in the table.
State
jN2Sþ1LσJPi Wave function
Predicted
mass [7]
Predicted
mass [8]
Predicted
mass [9]
Predicted
mass [13]
Predicted
mass [15]
Predicted
mass [14] Observed state
j02S12
þi 0Ψ
S00χλSzϕΩc
2698 2745 2718 2695 2731 2648(28) Ωcð2695Þj04S3
2
þi 0Ψ
S00χsSzϕΩc
2768 2805 2776 2767 2779 2709(32) Ωcð2770Þj12Pλ
1
2
−i 1Ψ
λ1Lz
χλSzϕΩc3055 3015 2977 3011 3030 2995(46)
j12Pλ3
2
−i 3029 3030 2986 2976 3033 3016(69) Ωcð3066Þ?j14Pλ
1
2
−i 1Ψ
λ1Lz
χsSzϕΩc2966 3040 2990 3028 3048
j14Pλ3
2
−i 3054 3065 2994 2993 3056 Ωcð3050Þ?j14Pλ
5
2
−i 3051 3050 3014 2947 3057 Ωcð3090Þ?j22Sλλ12þi 2
Ψλλ00χλSzϕΩc
3088 3020 3152 3100 Ωcð3119Þ?j24Sλλ32þi 2
Ψλλ00χsSzϕΩc
3123 3090 3190 3126 Ωcð3119Þ?
TABLE II. Spin-parity (JP) numbers of the newly observed Ωc states suggested in various works.
State [20] [21] [22] [24] [30] [26] [28] [29] [33] [27] This work
Ωcð3000Þ 1=2− 1=2− (3=2−) 1=2− 1=2− 1=2− 1=2− 1=2þ or 3=2þ 1=2− 1=2−
Ωcð3050Þ 1=2− 1=2− (3=2−) 1=2− 5=2− 3=2− 1=2− 5=2þ or 7=2þ 3=2− 3=2−
Ωcð3066Þ 1=2þ 1=2þ or 1=2− 3=2− (5=2−) 3=2− 3=2− 5=2− 3=2− 3=2− 1=2þ 3=2−
Ωcð3090Þ 3=2− (1=2þ) 3=2− 1=2− 1=2þ 3=2− 5=2− 1=2þ 5=2−
Ωcð3119Þ 3=2þ 3=2þ 5=2− (3=2þ) 5=2− 3=2− 3=2þ 5=2− 5=2þ or 7=2þ 3=2þ 1=2− 1=2þ or 3=2þ
FIG. 1. ssc system with λ- or ρ-mode excitations. ρ and λ are
the Jacobi coordinates defined as ρ ¼ 1ffiffi
2p ðr1 − r2Þ and
λ ¼ 1ffiffi
6p ðr1 þ r2 − 2r3Þ. q1 and q2 stand for the light s quarks,
and Q3 stands for the heavy c quark.
WANG, XIAO, ZHONG, and ZHAO PHYSICAL REVIEW D 95, 116010 (2017)
116010-2
[PRL 118 182001]
[PRD 95 11610]
Anticipate rich Ω∗∗−b spectrumAre some Ω∗∗0c s molecules/multiquarks?
gΞ+
+cc
obse
rvat
ion
11 / 15
The quark model predicts three JP = 1/2+ doubly charmed ground state baryons:Ξ+
cc (ccd) Ξ++cc (ccu) and Ω+
cc (ccs)Experimental evidence for Ξ+
cc in Λ+c K−π+ and pD+K− @ ≈ 3520 MeV from SELEX,
measuring an short lifetime and large production rate (< 33 fs @ 90 % CL, ≈ 20 % of Λ+c come from Ξ+
cc )
Null results from FOCUS, BaBar, Belle and LHCb (2011 1 fb−1 at√
s = 7 TeV)[Nucl. Phys. B Proc. Suppl. 115 33][PRD 74 011103][PRL 97 162001][JHEP 12(2013)090]
LHCb observed Ξ++cc in Λ+
c K−π+π+ using2016 data (1.7 fb−1 at
√s = 13 TeV)
Expected 3–4 times longer lifetime w.r.t.Ξ+
cc higher sensitivityFull event reconstruction in software triggerConfirmed with 2012 data(2 fb−1 at
√s = 8 TeV)
]2c) [MeV/++ccΞ(candm
3500 3600 3700
2 cC
andi
date
s pe
r 5
MeV
/
0
20
40
60
80
100
120
140
160
180
DataTotalSignalBackground
LHCb 13 TeV
[PRL 121 052002]
[PRL 89 112001][PLB 628 18]
m(Ξ++cc ) = 3621.40± 0.72(stat)± 0.27(syst)± 0.14(Λ+
c ) MeV
gΞ+
+cc
lifet
ime
and
Ξ++
cc→
Ξ+ ccπ
+
12 / 15
0.5 1 1.5 2Decay time [ps]
0.00
0.05
0.10
0.15
0.20
Arb
itrar
y sc
ale
LHCb++ccΞ0bΛ
3500 3550 3600 3650 37000
20
40
60
80
100
Can
dida
tes
/(5
MeV/c
2)
m(Ξ+c π+)
[MeV/c2
]
LHCb DataTotalSignalBackground
Lifetime of Ξ++cc expected to be enhanced by destructive Pauli interference
(valence u with u from weak c decay), and Ξ+cc shortened by W capture
τ(Ξ++cc ) = 0.256+0.024
−0.022(stat)± 0.014(syst) ps somewhat lower than expectationsInterfering c decay amplitudes can change dynamics of weak decay⇒ study further decay channels like Ξ++
cc → Ξ+ccπ
+
[PRL 121 052002] [arXiv:1807.01919]
Renewed interest in doubly heavy exotics (talks by Anthony Francis and Ahmed Ali)Search for doubly heavy ground state and excited baryons
gΞb(
6227
)−ob
serv
atio
n
13 / 15
Observed new Ξb(6227)− resonance in Λ0bK− and Ξ0
bπ− decays
Measured m and Γ in excl. hadronic Λ0b → Λ+
c π− decays; exploited high statistics
semileptonic (SL) Λ0b/Ξ0
b → Λ+c /Ξ+
c µ−νµ decays for production ratio measurements
SL: Infer νµ momentum from Λ0b/Ξ0
b mass constraint ≈ 20 MeV FWHM resolution
m(Ξb(6227)−) = 6226.9± 2.0(stat)± 0.3(syst)± 0.2(Λ0b) MeV
Γ(Ξb(6227)−) = 18.1± 5.4(stat)± 1.8(syst) MeVMeasured production ratios imply that B(Ξb(6227)− → Λ0
bK−) ≈ B(Ξb(6227)− → Ξ0bπ−)
]2c) [MeV/0bΛ(M −)
−K0
bΛ(M500 600 700 800 900
)2 cC
andi
date
s / (
8 M
eV/
100
200
300
400 Full fit−
K)−π+cΛ→(0
bΛ →−(6227)bΞ
Combinatorial
LHCb=13 TeVs
]2c) [MeV/0bΛ*(M −)
−K0
bΛ*(M500 600 700 800 900
)2 cC
andi
date
s / (
4 M
eV/
1000
2000
Full fit−
K)X−µ+cΛ→(0
bΛ →−(6227)bΞ
Combinatorial
LHCb=13 TeVs
]2c) [MeV/0bΞ*(M − )−π0
bΞ*(M400 600 800
)2 cC
andi
date
s / (
10 M
eV/
100
200
300
400 Full fit−π)X−µ+
cΞ→(0bΞ →−
(6227)bΞCombinatorial
LHCb=13 TeVs
[PRL 121 072002]
hadronic semileptonic Λ0b semileptonic Ξ0
b
gExc
ited
Ξ bsp
ectru
m
14 / 15
Interpretation of Ξb(6227)− as 1P orbital excitation of Ξb(5955)−(JP = 3/2− or 5/2−) preferred over 2S stateFuture: Search isospin partner; decays via Ξ′b and Ξ∗b could help to determine JP
the mass of the Ξbð6227Þ− under the 2S and 1P assign-
ments. To give further constraints on its quantum number,
we will investigate the strong decays in the following.
For carrying out the study of strong decay behaviors of the
discussed bottom-strange baryons, we employ the quark pair
creation (QPC) model [23–25] to calculate their two-body
OZI-allowed decays. The QPC model has been extensively
used to study the strong decays of different kinds of
hadrons. For a decay process of an excited bsq baryon state
(q designates a u or d quark), Aðqð1Þsð2Þbð3ÞÞ →Bðqð5Þsð2Þbð3ÞÞ þ Cðqð1Þqð4ÞÞ, the transition matrix
element in the QPC model is written as hBCjT jAi ¼δ3ðKB þKCÞMjA;jB;jCðpÞ, where the transition operator
T reads as
T ¼ −3γX
m
h1; m; 1;−mj0; 0iZZ
d3k4d3k5δ
3ðk4 þ k5Þ
× Ym1
k4 − k5
2
ωð4;5Þφð4;5Þ0 χ
ð4;5Þ1;−md
†
4ðk4Þd†5ðk5Þ ð2Þ
in a nonrelativistic limit. Here, the ωð4;5Þ0 and φ
ð4;5Þ0 are the
color and flavor wave functions of the q4q5 pair created from
the vacuum, respectively. Therefore, ωð4;5Þ ¼ ðRRþGGþBBÞ=
ffiffiffi
3p
and φð4;5Þ0 ¼ ðuuþ ddþ ssÞ=
ffiffiffi
3p
are color and
flavor singlets. The χð4;5Þ1;−m represents the pair production in a
spin triplet state. The solid harmonic polynomial Ym1 ðkÞ≡
jkjYm1 ðθk;ϕkÞ reflects the momentum-space distribution
of the q4q5. The dimensionless parameter γ describes the
strengthof the quark-antiquarkpair created from thevacuum.
The useful partial wave amplitude is related to the
helicity amplitude MjA;jB;jCðpÞ by
MA→BþCLS ðpÞ ¼
ffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2Lþ 1p
2JA þ 1
X
jB;jC
hL0JjAjJAjAi
× hJBjB; JCjCjJjAiMjA;jB;jCðpÞ; ð3Þ
where the Ji and ji (i ¼ A, B, and C) denote the total
angular momentum and their projection of initial and final
hadron states, respectively. L denotes the orbital angular
momenta between the final states B and C. Finally, thepartial width of A → BC is written in terms of the partial
wave amplitudes as
ΓðA → BCÞ ¼ 2πEBEC
MA
pX
L;S
jMLSðpÞj2 ð4Þ
in the A rest frame. To obtain the concrete expressions of
MjA;jB;jCðpÞ, an integral IlA;mlB;lC
ðpÞ should be performed,
which describes the overlap of the spatial functions of the
initial state (A), the created pair from the vacuum, and two
final states (B andC). Usually, the simple harmonic oscillator
(SHO) wave function ψmnrL
ðkÞ ¼ RnrLðβ;kÞYm
nrLðkÞ is
taken to construct the spatial wave function of a hadron
state. In this way, the analytical IlA;mlB;lC
ðpÞ can be extracted.
In our calculations, all values of the SHO wave function
scale (denoted as “β”), which reflect the distances between
the light diquark and the b quark in the bottomed baryons,
are obtained by reproducing the realistic root mean square
radius via Eq. (1). The results are collected in Table II. The
values of βs for the light diquark and other related hadrons
are taken from our previous work [19]. In this work, the
value of γ is taken as 1.296 since the measured widths
of 2S and 1P states of charmed and charmed-strange baryons
have been reproduced in Ref. [19].
With the preparation above, we first test our method by
calculating the partial widths of these observed 1S bottom
baryon states. At present, only the 1S bottomed baryons
have been reported by experiments in their OZI-allowed
decay channels. In Table III, wemake a comparison between
theoretical and experimental results of partial decay widths,
b
b
b
bK
bKbK
B
b 6227
b 5795
b 5935
b 5955
1S
2S
3S
1P
2P
1D
1S
2S
3S
1P
2P
1D
b b
5.8
6.0
6.2
6.4
6.6
6.8
5.8
6.0
6.2
6.4
6.6
6.8
Mass
inG
eV
FIG. 2. The obtained masses for the bottom-strange baryons.
The red solid lines (left) correspond to the predicted masses of Ξb
states which are composed of a good diquark and a bottom quark,
while the blue solid lines (right) correspond to the Ξ0b states which
contain a bad diquark. Here, we also listed the measured masses
of the ground states [1] and the Ξbð6227Þ− [9], which are marked
by “filled circle”.
TABLE II. The effective β values for the different bottomed
baryon states (in GeV).
States Λb Ξb Σb Ξ0b Ωb
1Sð1=2þÞ 0.288 0.341 0.345 0.367 0.404
1Sð3=2þÞ 0.334 0.355 0.390
2S 0.157 0.181 0.181 0.191 0.206
3S 0.115 0.131 0.132 0.139 0.148
1P 0.198 0.227 0.228 0.241 0.258
2P 0.131 0.149 0.150 0.158 0.169
1D 0.157 0.178 0.179 0.189 0.201
ROLE OF NEWLY DISCOVERED Ξbð6227Þ− FOR … PHYS. REV. D 98, 031502 (2018)
031502-3
] 2cm [MeV/δ0 10 20 30 40
2 cE
ntri
es p
er 0
.45
MeV
/
0
20
40
60
80
100
120
140
−π0bΞ
+π0bΞ
] 2cm [MeV/δ2 3 4 5
2 cE
ntri
es p
er 0
.1 M
eV/
05
101520253035
LHCb
[PRD 98 031502][PRL 114 062004]
Sensitivity boost from adding high statistics semileptonic channels
Ξ′b(5935)−Ξb(5955)∗−
gSum
mar
yan
dO
utlo
ok
15 / 15
Pattern in (non-exotic) spectroscopy: Search for 1. ground state and 2. excited states ininclusive decays. 3. Precision spectroscopy of excited states in amplitude analyses
Prospects and challenges in light hadron spectroscopyLarge statistics; large dynamical/non-perturbative effects challenging parametrisation of amplitude models
Prospects and challenges in (single) open charm spectroscopyEntering and laying foundation for precision charm spectroscopy
Prospects and challenges in beauty and double charm spectroscopyWe are at steps 1. and 2.; Step 3. requires much more data
Anticipate rich excited doubly charmed and Ωb spectrum
Bright future for spectroscopy at LHCb
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