[PPT] - St Status us and pr and prospect pects f for sp spectr trosc PowerPoint Presentation

SLIDE 1

St Status us and pr and prospect pects f for sp spectr trosc

scop
py stu

tudies s at t LH LHCb

Yuanning Gao (Tsinghua University) On Behalf of the LHCb Collaboration Joint BESIII-LHCb workshop Feb. 8-9, 2018

SLIDE 2

Ou Outline

In

Intr trod

ducti

tion

n t

to sp

spec

ectr trosc

scop
py s

stu tudies a es at t LH LHCb Cb

St

Studie ies of ch charmo rmonium st states

Ex

Excit ited c char armed m mesons

Ch

Charmed and doubly y charmed baryons

Ch

Charmonium-lik like states

Pe

Pentaquarks

Se

Sele lected topic ics on b-fl flavored hadrons

Fu

Future prospects

9/02/2018

Y. Gao, Spectroscopy at LHCb

2

SLIDE 3

LHCb LHCb Detect ctor

Fo Forward spectrometer running in pp collider

LHCb, Int. J. Mod. Phys. A30 (2015) 1530022

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Y. Gao, Spectroscopy at LHCb

3

Excellent vertex and IP, decay time resolution:

* IP ≈ 20/0m for high-23 tracks
* 4 ≈ 45/fs for 9:

% → ;/=> and 9: % → $: ?@A decays

Very good momentum resolution:

B2 2

⁄ ≈ 0.5% − 1% for 2 ∈ 0,200 /GeV

* LM ≈ 24/MeV for two-body decays

Hadron and Muon identification

OP→Q ≈ 95% for OS→Q ≈ 5% up to 100 GeV
OT→T ≈ 97% for OS→T ≈ 1 − 3%

Data good for analyses

> 99%
2 < η < 5 range: ∼ 25% of b¯

b pairs inside LHCb acceptance

SLIDE 4

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Y. Gao, Spectroscopy at LHCb

4

SLIDE 5

Physics cs program at LHCb LHCb

Not o
nly precision m

measurements i in b, c c se sectors

CKM a

and C CP-violation p parameters

rare d

decays

testing l

lepton u universality

…
But a

also a g general p purpose d detector

electroweak m

measurements: sin$%, W W/Z, t top q quark, . ..

spectroscopy, e

exotic h hadrons

soft Q

QCD

heavy i

ions

...

...

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Y. Gao, Spectroscopy at LHCb

5

SLIDE 6

Ex Experiment strategies

Advantage: h

high p production r rates

Challenge: r

reconstruct a an u unstable p particle f from O O(102) t tracks √ tr tracking → excellent m mass r resolution √ particle i identification → no. o

f c

combinations r reduced √ Vertexin xing → weakly d decayed p particles → particles f from b b/c d decays

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Y. Gao, Spectroscopy at LHCb

6

Primary Vertex (PV) Secondary Vertex (SV)

SLIDE 7

Ch Charmon

nia st

studies at LH LHCb

At

At LH LHCb ch charmonia ["" #] ma may be be acces essed ed by

[""

#] → '/)(→ +,+-) + 0

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Y. Gao, Spectroscopy at LHCb

7

LHCb-PAPER-2011-003 EPJC 71 (2011)1645 7 TeV 5.2 pb-1 LHCb-PAPER-2011-019 PLB 714 (2012) 215 7 TeV 36 pb-1

1"2,4 → '/) + 5 '/) → +,+- Primary Vertex (PV) Secondary Vertex (SV)

SLIDE 8

Muo Muoni nic de decays of

f !"# an

and !"$

1st

st ob

bser

servati tion

n of
f

!"#,$ → '/)*+*,

Co

Competitive mass and width measurements

9/02/2018

Y. Gao, Spectroscopy at LHCb

8

LHCb-PAPER-2017-036 PRL 119 (2017) 221801 1.0 fb-1 7 TeV 2.0 fb-1 8 TeV 1.9 fb-1 13TeV

!"# !"$

SLIDE 9

!/# $%('()

Ch Charmon

nia st

studies at LH LHCb

At

At LH LHCb ch charmonia [%% +] ma may be be acces essed ed by

[%%

+] → !/#(→ /0/1) + 3

%%

+ → 44 5

9/02/2018

Y. Gao, Spectroscopy at LHCb

9

Primary Vertex (PV) Secondary Vertex (SV) 6 7 → $% '( 3 = 9. ;; ± =. >9 ± =. ?@ ± =. >A6 ×'=1C D$%('E) = =. F? ± =. =@ ± =. =; ± =. => D!/#,6HI E = A JKL = =. F@ ± =. '' ± =. =@ ± =. =; D!/#,6 HI E = ; JKL

LHCb-PAPER-2014-029 EPJC 75 (2015) 311 0.7 fb-1 7 TeV 2.0 fb-1 8 TeV 0.7 fb-1 7 TeV

SLIDE 10

1.0 fb-1 7 TeV 2.0 fb-1 8 TeV

Ch Charmo monia from m !" → $$ %&"

Ex

Exclu lusiv ive r reconstructio ion: c cle lean an s sam ample le, b better c control l

f
f b

backg kgrou

und a

and r resol esoluti tion

n e

effec ects ts

9/02/2018

Y. Gao, Spectroscopy at LHCb

10

LHCb-PAPER-2016-016 PLB 769 (2017) 305

' ((

) = + !" → ((

) &" ×+( (( ) → $$ %) + !" → //1&" ×+(//1 → $$ %) '2( 34 = 5. 78 ± :. ;; ± :. :< ×5:=3 '1(;>>:) < 5:×5:=3 '@(;8>3) < :. 37 ×5:=3 B//1 − B2( 54 = 55:. 3 ± :. 7 ± :. < DEF B1(34) − B2( 34 = 73. 3 ± 5. > ± :. G DEF H

2( 54 = ;I. : ± 5. < ± 5. ; DEF

SLIDE 11

Ch Charmon

nia st

studies at LH LHCb

At

At LH LHCb ch charmonia ["" #] ma may be be acces essed ed by

[""

#] → '/)(→ +,+-) + 0

""

# → 11 2

""

# → 33

9/02/2018

Y. Gao, Spectroscopy at LHCb

11

Primary Vertex (PV) Secondary Vertex (SV)

LHCb-PAPER-2017-007 EPJC 77 (2017) 609

4 → "" # (→ 33) + 0

5"(67) 8"9 8"6 8": 5"(:7)

1.0 fb-1 7 TeV 2.0 fb-1 8 TeV

SLIDE 12

Ch Charmo monia from m ! → ## + %

Al

Allow to me measure product ction ratios

Co

Competitive measurements of masses of widths

9/02/2018

Y. Gao, Spectroscopy at LHCb

12

&' () → ##

RC1

C2 ≡ B(b → C1 X) × B(C1 → φ φ)

B(b → C2 X) × B(C2 → φ φ) Rχc0

ηc(1S) = 0.147 ± 0.023 ± 0.011,

Rχc1

ηc(1S) = 0.073 ± 0.016 ± 0.006,

Rχc2

ηc(1S) = 0.081 ± 0.013 ± 0.005,

Rχc1

χc0 = 0.50 ± 0.11 ± 0.01,

Rχc2

χc0 = 0.56 ± 0.10 ± 0.01,

Rηc(2S)

ηc(1S) = 0.040 ± 0.011 ± 0.004, Measured value World average [14] Mηc(1S) 2982.8 ± 1.0 ± 0.5 2983.4 ± 0.5 Mχc0 3413.0 ± 1.9 ± 0.6 3414.75 ± 0.31 Mχc1 3508.4 ± 1.9 ± 0.7 3510.66 ± 0.07 Mχc2 3557.3 ± 1.7 ± 0.7 3556.20 ± 0.09 Mηc(2S) 3636.4 ± 4.1 ± 0.7 3639.2 ± 1.2 ηc(1S) 31.4 ± 3.5 ± 2.0 31.8 ± 0.8 ηc(2S) – 11.3 + 3.2

− 2.9

LHCb-PAPER-2017-007 EPJC 77 (2017) 609

2980 2982 2984 2986 2988 20 25 30 35 40

Mηc(1S) [ MeV]

This measurement World average [14] Inclusive pp [15] Exclusive [60]

Γηc(1S) [ MeV]

LHCb

∆χ2 = 4 ∆χ2 = 1

* → &' + + &' → ,,

! → &' + %

&' → ## ,, → &' + % &' → ,,

SLIDE 13

!"#

(∗∗) sp

spect ctrosc scopy

St

Strange-ch charm states studied widely y to test QCD D models

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13

St States observed from B-fa factories and other experiments

!"

∗, !"= ∗

>?@A below DK threshold

States with unnatural spin-parity (#B = =D, @E, >D, … )

!"#

∗ (?=G=)

!"#

∗ (>HI=)

!"@

∗ (>A==)

!">

∗ (>JA?)

!"@(>J?I) !"@(>GI=) !"=

∗ (>?@A)

!"

∗

!"

SLIDE 14

!"#

(∗∗) sp

spect ctrosc scopy

St

Strange-ch charm states studied widely y to test QCD D models

9/02/2018

Y. Gao, Spectroscopy at LHCb

14

LHCb-PAPER-2012-016 JHEP 10 (2012) 151

St States observed from B-fa factories and other experiments

!"

∗, !"= ∗

>?@A below DK threshold

States with unnatural spin-parity (#B = =D, @E, >D, … )

!"#

∗ (?=G=)

!"#

∗ (>HI=)

!"@

∗ (>A==)

!">

∗ (>JA?)

!"@(>J?I) !"@(>GI=) !"=

∗ (>?@A)

!"

∗

!"

Inclusive KK → MENO, MONE + Q

MRS

∗ 2573 , MRX ∗ 2700 , MRZ ∗ (2860)

]

2

invariant mass [GeV/c

S

K

+

D

2.5 3

2

Candidates / 5 MeV/c

200 400

(c) LHCb

]

2

invariant mass [GeV/c

+

K D

2.5 3

2

Candidates / 5 MeV/c

1000 2000

(d) LHCb

1.0 fb-1 7 TeV

SLIDE 15

!"#

(∗∗) sp

spect ctrosc scopy

St

Strange-ch charm states studied widely y to test QCD D models

9/02/2018

Y. Gao, Spectroscopy at LHCb

15

LHCb-PAPER-2012-016 JHEP 10 (2012) 151

St States observed from B-fa factories and other experiments

!"

∗, !"= ∗

>?@A below DK threshold

States with unnatural spin-parity (#B = =D, @E, >D, … )

!"#

∗ (?=G=)

!"#

∗ (>HI=)

!"@

∗ (>A==)

!">

∗ (>JA?)

!"@(>J?I) !"@(>GI=) !"=

∗ (>?@A)

!"

∗

!"

Inclusive KK → MENO, MONE + Q

MRS

∗ 2573 , MRX ∗ 2700 , MRZ ∗ (2860)

Dalitz plot analysis ]R

O → M

^OND_E reveals two states MRX

∗ 2860 , MR` ∗ (2860)

LHCb-PAPER-2014-035 PRL 113 (2014) 162001 LHCb-PAPER-2014-036 PRD 90 (2014) 072003

SLIDE 16

Da Dalitz tz plot t analysis !" → $ %&'()*

~11K

K sign gnal events with purity 87%

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Y. Gao, Spectroscopy at LHCb

16

LHCb-PAPER-2014-035

PRL 113 (2014) 162001 LHCb-PAPER-2014-036 PRD 90 (2014) 072003 1.0 fb-1 7 TeV 2.0 fb-1 8 TeV

SLIDE 17

!"#

(∗∗) sp

spect ctrosc scopy

St

Strange-ch charm states studied widely y to test QCD D models

9/02/2018

Y. Gao, Spectroscopy at LHCb

17

LHCb-PAPER-2012-016 JHEP 10 (2012) 151

St States observed from B-fa factories and other experiments

!"

∗, !"= ∗

>?@A below DK threshold

States with unnatural spin-parity (#B = =D, @E, >D, … )

!"#

∗ (?=G=)

!"#

∗ (>HI=)

!"@

∗ (>A==)

!">

∗ (>JA?)

!"@(>J?I) !"@(>GI=) !"=

∗ (>?@A)

!"

∗

!"

Inclusive KK → MENO, MONE + Q

MRS

∗ 2573 , MRX ∗ 2700 , MRZ ∗ (2860)

Dalitz plot analysis ]R

O → M

^OND_E reveals two states MRX

∗ 2860 , MR` ∗ (2860)

LHCb-PAPER-2014-035 PRL 113 (2014) 162001 LHCb-PAPER-2014-036 PRD 90 (2014) 072003

Inclusive KK → M∗ENO, M∗ONE + Q

MRX

∗ 2536 , MRS ∗ 2573 , MRX ∗ 2700 , MR` ∗ 2860 , MRZ ∗ (3040)

LHCb-PAPER-2015-052 JHEP 02 (2016) 133

SLIDE 18

In Inclusive e analysis !! → ($∗&'(, $∗('&) + ,

Re

Resonant contribution seen due to -./

∗ 2536 , -.4 ∗ 2573 , -./ ∗ 2700

and

.7

∗ 2860 , weak evidence of -.9 ∗ (3040)

Angular distribution reflect

cts the spin-pa pari rity a assignm nment ;<=>?@ Na Natural Spin-Pa Parity A + BCD;>?@ Un Unnatural Spin-Pa Parity

9/02/2018

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18

1.0 fb-1 7 TeV 2.0 fb-1 8 TeV

∗& → -EF&, -E → GHF& sample

$IJ

∗∗ → $K'

rest frame ?@: angle between K'

LHCb-PAPER-2015-052 JHEP 02 (2016) 133

SLIDE 19

tests vy the

S

1 1

S

3

P

3 1

P

2

P

3 1

D

3 2

D

3

D

3 2

F

3 3

F

4

F

3

)

2

c Mass (MeV/

1600 1800 2000 2200 2400 2600 2800 3000 3200 3400

Ds D∗

s

D∗

s0(2317)

Ds1(2460) Ds1(2536) D∗

s2(2573)

D∗

s1(2700)

D∗

s1(2860)

D∗

s3(2860)

DsJ (3040) JP = 0− 1− 0+ 1+ 2+ 1− 2− 3− 2+ 3+ 4+

Po Possible assignment of !"#

(∗∗)st

states

Re

Recent theory predictions

S.

S. Godfrey, I. T. Jardine, PR

PRD 89 (2014) 072043

Tw

Two states observed by LH LHCb co could fit into the 1D 1D st states

At

At least three more states ex expected up to 3 GeV/c2

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Y. Gao, Spectroscopy at LHCb

19

SLIDE 20

S

1 1

S

3

P

3 1

P

2

P

3 1

D

3 2

D

3

D

3 2

F

3 3

F

4

F

3

)

2

c Mass (MeV/

1600 1800 2000 2200 2400 2600 2800 3000 3200 3400

D0 D∗0 D∗

0 (2400)0

D1(2420)0 D1(2430)0 D∗

2 (2460)0

D(2550)0 D∗

1 (2760)0

D∗

J (2650)0

D∗

J (2600)0

D∗

J (2760)0

DJ (2740)0 DJ (3000)0 JP = 0− 1− 0+ 1+ 2+ 1− 2− 3− 2+ 3+ 4+ theory predictions from PRD 93 (2016) 034035 Heavy Quark Spectroscopy at LHCb 14

!"

#(∗∗) sp

spect ctrosc scopy

Si

Similar for

r !"

#(∗∗) sp

spectrosc scopy

Re

Recent theory predictions

S.

S. Godfrey, K. Moats, PR

PRD 93 (2016) 034035

Inc

Inclus usive e studi udies es

'('), ++ → !(∗)(-).

Da Dalitz pl plot ana nalyses es

/# → ! 0#-(-) /# → ! 0#1(-)

Ne

New states so some have unknown "2

9/02/2018

Y. Gao, Spectroscopy at LHCb

20

LHCb-PAPER-2013-026 JHEP 09 (2013) 145 BaBar, PRD 82(2011) 111101 LHCb-PAPER-2015-017 PRD 92 (2015) 012012 LHCb-PAPER-2014-070 PRD 92 (2015) 032002

SLIDE 21

Da Dalitz tz plot t analysis !" → $%&"&"

~28000 events with 1% backgr

ground

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Y. Gao, Spectroscopy at LHCb

21

LHCb-PAPER-2016-026 PRD 94 (2016) 072001 1.0 fb-1 7 TeV 2.0 fb-1 8 TeV

SLIDE 22

Po Possible assignment of !"

#(∗∗)st

states

9/02/2018

Y. Gao, Spectroscopy at LHCb

22

significances

either

S

1 1

S

3

P

3 1

P

2

P

3 1

D

3 2

D

3

D

3 2

F

3 3

F

4

F

3

)

2

c Mass (MeV/

1600 1800 2000 2200 2400 2600 2800 3000 3200 3400

D0 D∗0 D∗

0 (2400)0

D1(2420)0 D1(2430)0 D∗

2 (2460)0

D(2550)0 D∗

1 (2760)0

? ? D∗

2 (3000)0

DJ (3000)0 DJ (2740)0 D∗

3 (2760)0

D∗

1 (2680)0

JP = 0− 1− 0+ 1+ 2+ 1− 2− 3− 2+ 3+ 4+ Heavy Quark Spectroscopy at LHCb 19

S

1 1

S

3

P

3 1

P

2

P

3 1

D

3 2

D

3

D

3 2

F

3 3

F

4

F

3

)

2

c Mass (MeV/

1600 1800 2000 2200 2400 2600 2800 3000 3200 3400

D0 D∗0 D∗

0 (2400)0

D1(2420)0 D1(2430)0 D∗

2 (2460)0

D(2550)0 D∗

1 (2760)0

D∗

J (2650)0

D∗

J (2600)0

D∗

J (2760)0

DJ (2740)0 DJ (3000)0 JP = 0− 1− 0+ 1+ 2+ 1− 2− 3− 2+ 3+ 4+ theory predictions from PRD 93 (2016) 034035 Heavy Quark Spectroscopy at LHCb 14

SLIDE 23

Ob Observation o

f e

exited !" st states

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Y. Gao, Spectroscopy at LHCb
Excited #$

%, '$, ($ states have been reported but no excited )$ *

states were observed before LHCb

3 fb-1 Run I + 0.3 fb-1 Run II ++ collisions data
Decay: !$

∗∗* → .$ %/0, .$ % → +/01%

LHCb, PRL 118 (2017) 182001 23 ≈ 7 MeV Purity ≈ 83%

Cabibbo suppressed decay, but much higher reconstruction efficiency PV

Ξ:

%

;, <0, =% <% IP

23

SLIDE 24

Ob Observation o

f e

exited !" st states

9/02/2018

Y. Gao, Spectroscopy at LHCb
5 narrow states & evidence for 6th broader state at high mass

LHCb, PRL 118 (2017) 182001 Ξ$

%&'( threshold

Feed-down Feed-down: Ω$

∗∗+ → '(Ξ$ %&, Ξ$ %& → .Ξ$ &,

/ Ξ$

&'( mass peaks shifted

24 01 = Δ45

6.4 Even at the most powerful particle accelerator

n Earth, the discovery of a new particle is a big
deal. Finding five new baryons in one go, as the

Large Hadron Collider beauty experiment (LHCb) has done, is truly historical.

Matteo Rini

Physics

SLIDE 25

Ob Observation o

f e

exited !" st states

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Y. Gao, Spectroscopy at LHCb
Matching between observed peaks and predictions requires spin-

parity information: studied with three-body decays or in decays of heavier baryons

LHCb, PRL 118 (2017) 182001

25

See backup pages for the references

SLIDE 26

Predicted to form two SU(4) baryon 20-plets with !" =

$ % &

and !" =

' % &

, each contains a SU(3) triplet with two c quarks: ())

& ))* , ()) && )), , -)) & ())/)

!" =

' % &

expected to decay to

$ % &

states via strong/electromagnetic interaction

!" =

$ % &

states decay weakly with a ) quark transformed to lighter quarks

9/02/2018

12 = 1 2

&

12 = 3 2

&

Y. Gao, Spectroscopy at LHCb

Doubly ch charmed baryons

26

SLIDE 27

Masses of ground state and excitations by many theoretical models

ØPredicted !""

#,## masses %. ' − %. ) GeV, * +"" #

≈ * !"" + .. / GeV ØMass splitting between !""

# and !"" ## only a few MeV due to 0, 1 symmetry

Lattice QCD computations:

Lifetime known to be affected by

spectator + non-spectator + Pauli interference 2(!""

##(""0)) ≫ 2(!"" # (""1))

2 !66

## ∈ [ :.. − )..] fs

9/02/2018

"

<

diquark

"

HQET: two charm quarks considered as a heavy diquark, doubly heavy baryon similar to a heavy meson => * !"" ≈ %. ? GeV, * +""

#

≈ %. ) GeV

Y. Gao, Spectroscopy at LHCb

See backup pages for the references

Ma Masses and nd lifeti times

27

SLIDE 28

PLB 628 (2005) 18

Ξ""

# → Λ" #&'(#

Ξ""

# → )*#&'

PRL 89 (2002) 112001

SELEX (Fermilab E781) collides high energy hyperon beams (+', -) with

nuclear targets, dedicated to study charm baryons

Observed .//

# (//1) in .// # → 3/ #4'5# and .// # → -6#4' decays

9/02/2018

Y. Gao, Spectroscopy at LHCb

Ø Short lifetime: 7 Ξ""

#

< 33 fs @90% CL, but not zero Ø Large production: : =

< =>>

? ×AB(=>>

? →C> ?DEF?)

<(C>

?)

∼ 20% Ø Mass (combined): 3518.7 ± 1.7 MeV

Re Results fro rom SELEX

28

15.9 signals 5.62 signals

SLIDE 29

SELEX results not confirmed by FOCUS, BaBar & Belle
LHCb searched for !""

# → %" #&'(# decay with ). +, fb-1 of 7 TeV data

Ø- %"

# ≈ ). / M, requiring high-01

ØNo significant peaking structure observed with 2 ∈ [5. 5, 5. /] GeV ØExperiment sensitivity strongly depends on !""

# lifetime

9/02/2018

Y. Gao, Spectroscopy at LHCb

89 = 9 ;<'=#

>?

@<'=# − 9

;<'=#

>?

@ − 9(<') − 9(=#)

SELEX ΞEE

#

SELEX ΞEE

#

F =

G H??

@ ×JK(H?? @ →>? @LMN@)

G(>?

@)

< 0.013 for S = 100 fs, < 3.3×10'T for S = 400 fs @ 95% CL

LHCb-PAPER-2013-049 JHEP 12 (2013) 090

Pr Previous studies from LHCb LHCb

29

SLIDE 30

Expected to have longer lifetime than !""

# , higher sensitivity at LHCb

Decay: !""

## → %" #&'(#(#, branching fraction up to 10%

LHCb run II at ) = +, TeV, ~+. / fb-1

Ø ,+, ± ,, events, +12 Ø 8TeV data analyzed for cross-check, /2 Ø Consistent with weakly decays Ø

~ 100 MeV above SELEX !33

# peaks

9/02/2018

Y. Gao, Spectroscopy at LHCb

Yu et al., arXiv:1703.09086

4""

## ""5 at

at LHCb LHCb

LHCb-PAPER-2017-018 PRL 119 (2017) 112001

30

PV !""

##

%"

#

Ξ77

## → 8'9#9#Λ7 # → ;8'9#

< !""

## = ,=1+. >? ± ?. /1(ABCB) ± ?. 1/(AEAB) ± ?. +>(%" #) MeV

SLIDE 31

!(#$%&)

Ob

Observed by by Belle in 2003

CD

CDF determined the quantum numbers to be ()* = ,-- or

r &/-
LH

LHCb de deter ermi mined ned ()* = ,-- wi with th , 01/, of

f data

Belle, PRL 91 (2003) 262001

9/02/2018 31

2-2/ spectrum consistent with 45

CDF, PRL 98 (2007) 132002 LHCb-PAPER-2013-001, PRL 110 (2013) 222001

Both CDF and LHCb assumed the decay dominated by the lowest angular momentum 6789

:± → !=±, ! → (/@A-A/

Y. Gao, Spectroscopy at LHCb

SLIDE 32

!(#$%&) quan quantum tum numbe number de determina minatio tion

Re

Re-an analy alysis is usin ing 3 )*+, of

f data withou
ut -./0 as

assumptio ion

9/02/2018 32

LHCb-PAPER-2015-015 PRD 92 (2015) 011102 (R)

123 = 166 confirmed D-wave fraction < 4%

Y. Gao, Spectroscopy at LHCb

SLIDE 33

An

Analyses using g 3 fb$% of

f data
An

An impor

rtant

t ingr gredient t to

reveal th

the natu ture of

f &(()*+)

& ()*+ → ./01, 0 +3 1

9/02/2018 33

LHCb-PAPER-2014-008 NPB 886 (2014) 665

LHCb

Y. Gao, Spectroscopy at LHCb

45 → ./0165 &(()*+) → ./01

LHCb

45 → 0 +3 165 &(()*+) → 0(+3)1

7. 79 evidence

B(X(3872) → ψ(2S)γ) B(X(3872) → J/ψγ) = 2.46 ± 0.64 ± 0.29,

SLIDE 34

! ""#$ %

Or

Originally found by Belle in &$ → ( )* +%,-

Ba

BaBa Bar co could not co confirm

9/02/2018

Y. Gao, Spectroscopy at LHCb

34

Belle, PR D88 (2013) 074026 BaBar, PR D79 (2009) 112001 Belle, PRL 100 (2008) 142001 Belle, PR D80 (2009) 031104

SLIDE 35

! ""#$ %

LH

LHCb f full a amplitude a analysis u using # '(%)

*+ = )- is

is confir firmed

Ar

Argand plo plot sh shows s a clear re resonance feature re

9/02/2018 35

LHCb-PAPER-2014-014 PRL 112 (2014) 222002

Y. Gao, Spectroscopy at LHCb

SLIDE 36

! → #/%&

Na

Narrow structure in #/%& di discover ered ed by CDF, confirmed med by D0 an and CMS. No No evi vidence by Ba BaBa Bar/B /Belle/LH LHCb(0. (0.37 37 fb fb-1)

9/02/2018 36

Y. Gao, Spectroscopy at LHCb

)

2

M (GeV/c ∆

1 1.1 1.2 1.3 1.4 1.5

2

Candidates/10 MeV/c

1 2 3 4 5 6 7 8 9

b)

PRL 102(2009) 242002

CDF

PRD 89(2014) 242002 PLB 734(2014) 261

CMS D0

SLIDE 37

Exotic c states in !" → $/&'("

LH

LHCb per perform m ful ull 6D ampl mplitude ude ana nalysis

4

4 peak aks s ar are obse served wit ith X(4140) (4140) wid ider than an CDF/DO/CMS

9/02/2018 37

Y. Gao, Spectroscopy at LHCb

LHCb-PAPER-2016-018 PRL 118 (2017)022003 LHCb-PAPER-2016-019 PRD 95 (2017) 012002

Significant larger at LHCb

)

*+,

.//.0/-12 = 45. 7 ± 9. : MeV

SLIDE 38

Pe Pentaquark st studies

9/02/2018

Y. Gao, Spectroscopy at LHCb

38

SLIDE 39

Di Discovery y of pe pentaqua quark rk st states

Tw

Two pen pentaqua quark st states observed in !"

# → %/'()*

LHCb, PRL 115(2015) 072001 +,(../#) +,(.12#)

9/02/2018

Y. Gao, Spectroscopy at LHCb

39

SLIDE 40

Di Discovery y of pe pentaqua quark rk st states

Am

Amplitu tude analysis reveals th the prop

perti

ties

Co

Confirmed by y a a mode del l inde indepe pende ndent analy analysis sis

Pr

Production & deca cay

LHCb, PRL 115(2015) 072001

9/02/2018

Y. Gao, Spectroscopy at LHCb

B(Λ0

b → P+ c (4380)K −)B(P+ c → J/ψp) =

2.56 ± 0.22 ± 1.28 + 0.46

− 0.36

× 10−5

B(Λ0

b → P+ c (4450)K −)B(P+ c → J/ψp) =

1.25 ± 0.15 ± 0.33 + 0.22

− 0.18

× 10−5

LHCb-PAPER-2016-009 PRL 117 (2016) 082002 LHCb-PAPER-2015-032

Chin. Phys. C 40 (2016) 011001

40

SLIDE 41

St Study of !"

# → %/'()*

9/02/2018

Y. Gao, Spectroscopy at LHCb
Ca

Cabbibo suppressed mode with less statistics

Ex

Exotic + co contributions in %/')

Fit with 2 pentaquarks + ,-(4200) favored by 3σ compared to

no exotic contributions

LHCb-PAPER-2016-015 PRL 117(2016) 082003

41

345 > 1.8 GeV

SLIDE 42

Ob Observation o

f

!"

# → %&',)*+,

9/02/2018

Y. Gao, Spectroscopy at LHCb
-& ../# cl

close to %&'* th threshold, tr triangle singularity ty ?

St

Study with radiative %&0 → 0/23 de decays Ma Mass c cons nstraint o

n

n %&' to improve resolution, force ces %&) to to lower mass

Fi

First t observati tion of th this mo mode, full amplitude e analysi sis s foreseen eseen with RUNII II data added ed in

42

LHCb-PAPER-2017-011, PRL 119 (2017) 062001 Guo et al., PR D92(2015) 071502

Suppressed in 5 → 6789 decays

Belle, PRD 78 (2008) 072004 BaBar, PRL 102 (2009) 132001 LHCb, NPB 874 (2013) 663

SLIDE 43

Ob Observation o

f

!"

# → %/'()#

9/02/2018

Y. Gao, Spectroscopy at LHCb
Lo

Look f for *+,- .- pen pentaqua quark in in this is mode

Fi

First obse servation with RUNI data

~3

~300 candidates seen

( ( on

ne of
f the two
wor
rld best measurements)
Fu

Full amplitude analysi sis s forese seen with RUN RUNII data added in

LHCb-PAPER-2016-053 PLB 772 (2017) 265

43

Wu et al., PRL 105 (2010) 232001 Chen et al., PRC 93 (2016) 065203

É0, ± :8 (4.19 ± 0.29 ± 0.15)×10-2

/ decays In vertex detector / decays after vertex detector

SLIDE 44

9/02/2018

Y. Gao, Spectroscopy at LHCb

44

!"#

$%&' )*+, = 3325 ± 73

34

∗ 67 → 34 (∗);<;=

LHCb-PAPER-2017-042 arXiv:1712.04094 ATLAS, PRL 113 (2014) 212004

>"#(?@) = 6842 ± 4 ± 5 MeV

G. 6I

!"#

J*$JK

SLIDE 45

9/02/2018

Y. Gao, Spectroscopy at LHCb

45

∈ R = σB(∗)

c

(2S)+

σB+

c

· B(B(∗)

c (2S)+ → B(∗)+ c

π+π−) = NB(∗)

c

(2S)+

NB+

c

· εB+

c

εB(∗)

c

(2S)+

,

√s = 7 TeV √s = 8 TeV ATLAS (0.22 ± 0.08 (stat))/ε7 (0.15 ± 0.06 (stat))/ε8 LHCb – < [0.04, 0.09]

!", !$: relative efficiencies of reconstructing &'

∗ )* + wrt &' +

ATLAS did not publish !", !$
More studies needed to resolve the large tension

between ATLAS and LHCb.

LHCb-PAPER-2017-042 arXiv:1712.04094

SLIDE 46

Searches for weakl kly y decayi ying b-fl flavor

red pe

pentaquar aquarks

9/02/2018

Y. Gao, Spectroscopy at LHCb
Sk

Skyrme mo model del pr predi ediction n on n pen pentaqua quark st state: th the heavier r th the co constitute quarks ks, the more tightly bound the pen pentaqua quark st state

Se

Search for

r masses below stron
ng

g decay threshol

ld
No

No evi vidence observed (yet)

LHCb-PAPER-2017-043 arXiv:1712.08086

46

Upper limit set on relative !×# as a function of P masses

PLB 590(2004) 185; PLB 586(2004)337; PLB 331(1994)362

+

d u b u d d c u u d

}

}p

}

c s

ψ J/ K

figure by Stone

(a)

{

PB p

+

u u}

+

π−

SLIDE 47

Prospect ct: RUNI+RUNII II

Data samples

es

1

1 fb-1 (7 (7 Te TeV)+ )+ 2 fb fb-1 (8 (8 Te TeV)

~6

~6 fb fb-1 at at 13 Te TeV with !""

# %&'() /!"" # +'() ≈ -

A

A far from completed list benifited from full RUNI+RUNII data

se

search for excited ./ st states

pr

precise 01 &2+- − 04 -5 , , new decay modes

pr

prope perties of 6//

77:

: lifetime me, production cross-se sections, s, ne new de decay mode des, ...

se

searches s for 6//

7 , 9// 7 , 6"/ 7 , 6"/ : …

<= of
f =/ >&2: & =/ >>@: , ne

new de decay mode des

am

amplitu litude e an analy alysis is A"

: → C/%,-DEF,

, cusp sp?

am

amplitu litude e an analy alysis is 6"

F → </4GEF,

, new pentaquarks? s? …. ….

9/02/2018

Y. Gao, Spectroscopy at LHCb

47

SLIDE 48

Spectroscopy y with the upgraded LH LHCb

LH

LHCb wi will be upgraded in 2019, softw tware tri trigger r wi with th 40MH MHz

Al

Allow PID at t th the tr trigger level – gr great increase (~2x) of

f trigger

efficiency on

n full hadron
nic final states
A

A new com

mputi

ting g approa

ach to
data-an

analy alysis is is is needed

9/02/2018

Y. Gao, Spectroscopy at LHCb

48

SLIDE 49

Su Summary ry

LH

LHCb Cb has made important contributions to the kn knowledge of

f h

hadron

n sp

spec ectr trosc

scop
py

Ob Observation/study of exci cited !(#)mes mesons ns & %(&) ba baryons ns Ob Observation/study of exotic c states Di Discovery of doubly ch charmed baryons

…
St

Stay tu tuned ed wit with ne new resul ults from RUNI+RUNII

Sp

Spectroscopy at the upgrad aded LH LHCb Cb is is challe allengin ing an and pr promising ng

9/02/2018

Y. Gao, Spectroscopy at LHCb

49

SLIDE 50

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Y. Gao, Spectroscopy at LHCb

50

Backup slides

SLIDE 51

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Y. Gao, Spectroscopy at LHCb

51

[3] D. Ebert, R. N. Faustov, and V. O. Galkin, Masses of excited heavy baryons in the relativistic quark-diquark picture, Phys. Lett. B659 (2008) 612, arXiv:0705.2957. [4] W. Roberts and M. Pervin, Heavy baryons in a quark model, Int. J. Mod. Phys. A23 (2008) 2817, arXiv:0711.2492. [5] H. Garcilazo, J. Vijande, and A. Valcarce, Faddeev study of heavy-baryon spectroscopy,

J. Phys. G34 (2007) 961, arXiv:hep-ph/0703257.

[6] S. Migura, D. Merten, B. Metsch, and H.-R. Petry, Charmed baryons in a relativistic quark model, Eur. Phys. J. A28 (2006) 41, arXiv:hep-ph/0602153. [7] D. Ebert, R. N. Faustov, and V. O. Galkin, Spectroscopy and Regge trajectories of heavy baryons in the relativistic quark-diquark picture, Phys. Rev. D84 (2011) 014025, arXiv:1105.0583. [8] A. Valcarce, H. Garcilazo, and J. Vijande, Towards an understanding of heavy baryon spectroscopy, Eur. Phys. J. A37 (2008) 217, arXiv:0807.2973. [9] Z. Shah, K. Thakkar, A. K. Rai, and P. C. Vinodkumar, Mass spectra and Regge trajectories of Λ+

c , Σ0 c, Ξ0 c and Ω0 c baryons, Chin. Phys. C40 (2016) 123102,

arXiv:1609.08464. [10] J. Vijande, A. Valcarce, T. F. Carames, and H. Garcilazo, Heavy hadron spectroscopy: A quark model perspective, Int. J. Mod. Phys. E22 (2013) 1330011, arXiv:1212.4383.

References: Ω∗∗ mass

SLIDE 52

9/02/2018

Y. Gao, Spectroscopy at LHCb

52

References: Ω"

∗ masses (cont’d)

[11] T. Yoshida et al., Spectrum of heavy baryons in the quark model, Phys. Rev. D92 (2015) 114029, arXiv:1510.01067. [12] H.-X. Chen et al., P-wave charmed baryons from QCD sum rules, Phys. Rev. D91 (2015) 054034, arXiv:1502.01103. [13] H.-X. Chen et al., D-wave charmed and bottomed baryons from QCD sum rules, Phys.

Rev. D94 (2016) 114016, arXiv:1611.02677.

[14] G. Chiladze and A. F. Falk, Phenomenology of new baryons with charm and strangeness, Phys. Rev. D56 (1997) R6738, arXiv:hep-ph/9707507. [15] M. Padmanath, R. G. Edwards, N. Mathur, and M. Peardon, Excited-state spectroscopy of singly, doubly and triply-charmed baryons from lattice QCD, arXiv:1311.4806.

SLIDE 53

9/02/2018

Y. Gao, Spectroscopy at LHCb

53

References: Ξ"" masses

[6] S. S. Gershtein, V. V. Kiselev, A. K. Likhoded, and A. I. Onishchenko, Phys. Atom. Nucl. 63, 274 (2000), [Yad.

Fiz. 63, 334 (2000)], arXiv:hep-ph/9811212 [hep-ph].

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A. I. Onishchenko, Mod. Phys. Lett. A14, 135 (1999),

arXiv:hep-ph/9807375 [hep-ph]. [8] C. Itoh, T. Minamikawa, K. Miura, and T. Watanabe,

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[9] S. S. Gershtein, V. V. Kiselev, A. K. Likhoded, and A. I. Onishchenko, Phys.Rev. D62, 054021 (2000). [10] K. Anikeev et al., in Workshop on B physics at the Teva- tron: Run II and beyond, Batavia, Illinois, September 23-25, 1999 (2001) arXiv:hep-ph/0201071 [hep-ph]. [11] V. Kiselev and A. Likhoded, Phys.Usp. 45, 455 (2002), arXiv:hep-ph/0103169 [hep-ph]. [12] D. Ebert, R. Faustov, V. Galkin, and A. Martynenko, Phys.Rev. D66, 014008 (2002), arXiv:hep-ph/0201217 [hep-ph]. [13] D.-H. He, K. Qian, Y.-B. Ding, X.-Q. Li, and P.-N. Shen, Phys.Rev. D70, 094004 (2004), arXiv:hep-ph/0403301 [hep-ph]. [14] C.-H. Chang, C.-F. Qiao, J.-X. Wang, and X.-G. Wu, Phys.Rev. D73, 094022 (2006), arXiv:hep-ph/0601032 [hep-ph]. [15] W. Roberts and M. Pervin, Int.J.Mod.Phys. A23, 2817 (2008), arXiv:0711.2492 [nucl-th]. [16] A. Valcarce, H. Garcilazo, and J. Vijande, Eur.Phys.J. A37, 217 (2008), arXiv:0807.2973 [hep-ph]. [17] J.-R. Zhang and M.-Q. Huang, Phys.Rev. D78, 094007 (2008), arXiv:0810.5396 [hep-ph]. [18] Z.-G. Wang, Eur.Phys.J. A45, 267 (2010), arXiv:1001.4693 [hep-ph]. [19] M. Karliner and J. L. Rosner, Phys. Rev. D90, 094007 (2014), arXiv:1408.5877 [hep-ph]. [20] K.-W. Wei, B. Chen, and X.-H. Guo, Phys. Rev. D92, 076008 (2015), arXiv:1503.05184 [hep-ph]. [21] Z.-F. Sun and M. J. Vicente Vacas, Phys. Rev. D93, 094002 (2016), arXiv:1602.04714 [hep-ph]. [22] C. Alexandrou and C. Kallidonis, (2017), arXiv:1704.02647 [hep-lat]. [23] B. O. Kerbikov, M. I. Polikarpov, and L. V. Shevchenko,

Nucl. Phys. B331, 19 (1990).

[24] S. Fleck and J.-M. Richard, Prog. Theor. Phys. 82, 760 (1989). [25] S. Chernyshev, M. A. Nowak, and I. Zahed, Phys. Rev. D53, 5176 (1996), arXiv:hep-ph/9510326 [hep-ph]. [26] T. M. Aliev, K. Azizi, and M. Savcı, Nucl. Phys. A895, 59 (2012), arXiv:1205.2873 [hep-ph]. [27] Z.-F. Sun, Z.-W. Liu, X. Liu, and S.-L. Zhu, Phys. Rev. D91, 094030 (2015), arXiv:1411.2117 [hep-ph]. [28] N. Mathur, R. Lewis, and R. M. Woloshyn, Phys. Rev. D66, 014502 (2002), arXiv:hep-ph/0203253 [hep-ph]. [29] Y. Namekawa et al. (PACS-CS collaboration), Phys. Rev. D87, 094512 (2013), arXiv:1301.4743 [hep-lat]. [30] Z. S. Brown, W. Detmold, S. Meinel, and K. Orginos,

Phys. Rev. D90, 094507 (2014), arXiv:1409.0497 [hep-

lat]. [31] M. Padmanath, R. G. Edwards, N. Mathur, and M. Peardon, Phys. Rev. D91, 094502 (2015), arXiv:1502.01845 [hep-lat]. [32] P. P´ erez-Rubio, S. Collins, and G. S. Bali, Phys. Rev. D92, 034504 (2015), arXiv:1503.08440 [hep-lat]. [33] Y. Liu and I. Zahed, Phys. Rev. D95, 116012 (2017), arXiv:1704.03412 [hep-ph]; (2017), arXiv:1705.01397

SLIDE 54

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Y. Gao, Spectroscopy at LHCb

54

References: Ξ"" lifetimes

[10] K. Anikeev et al., in Workshop on B physics at the Teva- tron: Run II and beyond, Batavia, Illinois, September 23-25, 1999 (2001) arXiv:hep-ph/0201071 [hep-ph]. [11] V. Kiselev and A. Likhoded, Phys.Usp. 45, 455 (2002), arXiv:hep-ph/0103169 [hep-ph]. [19] M. Karliner and J. L. Rosner, Phys. Rev. D90, 094007 (2014), arXiv:1408.5877 [hep-ph]. [24] S. Fleck and J.-M. Richard, Prog. Theor. Phys. 82, 760 (1989). [37] B. Guberina, B. Meli´ c, and H. ˇ Stefanˇ ci´ c, Eur.Phys.J. C9, 213 (1999), arXiv:hep-ph/9901323 [hep-ph]. [38] V. Kiselev, A. Likhoded, and A. Onishchenko, Phys.Rev. D60, 014007 (1999), arXiv:hep-ph/9807354 [hep-ph]. [39] C.-H. Chang, T. Li, X.-Q. Li, and Y.-M. Wang, Com- mun.Theor.Phys. 49, 993 (2008), arXiv:0704.0016 [hep- ph]. [40] A. V. Berezhnoy and A. K. Likhoded, Phys. Atom. Nucl. 79, 260 (2016), [Yad. Fiz. 79, 151 (2016)].

SLIDE 55

LHCb LHCb Trigger er in RUN N II II

TU TURBO BO stream introduced in 2015

5

5 kHz of f 12 12 kHz go to TURBO

On

Only trigger information saved → sm smaller r event, faster r analysi sis

Us

Used for

r high

gh yield exclusive tri trigger r lines: "/$, &', &(, …

9/02/2018 55

Y. Gao, Spectroscopy at LHCb

SLIDE 56

Amp Amplitu tude e analysis of !"

# → %/'()

9/02/2018 56

“s

“something new” is clear shown in the Da Dalitz pl plot

LHCb, PRL 115(2015) 072001

Y. Gao, Spectroscopy at LHCb

SLIDE 57

Amp Amplitu tude e analysis of !"

# → %/'()

9/02/2018 57

Tw

Two models to deal with !∗ → () co contributions

LHCb, PRL 115(2015) 072001

Y. Gao, Spectroscopy at LHCb

SLIDE 58

Lifetimes known to be affected by spectator decays + non-spectator decays

and Pauli interference, qualitatively

Expectation: !(Ξ$$

%%(&&')) ≫ !(Ξ$$ % (&&*))

Calculations give ! Ξ++

%% ∈ [ 200 − 700] fs

9/02/2018

Spectator (Γ

5)

6-exchange (6)

* 7∗ & 9 ' ' 7∗('*̅) 9 & '/s * '/9 '

Y. Gao, Spectroscopy at LHCb

See backup pages for references

Doubly ch charmed baryons

58

SLIDE 59

FOCUS (Fermilab E831) studies charm hadrons produced in photon-nuclear

fixed target collisions

FOCUS didn’t confirm Ξ""

# observed by SELEX in Λ" #%&'#decay

9/02/2018

SELEX Ξ""

#

Other modes also studied: Ξ""

# → Λ" #), +,)

+#), no SELEX-like signal peak observed

Y. Gao, Spectroscopy at LHCb
Nucl. Phys. Proc. Suppl. 115 (2003) 33

Re Results fro rom FOCUS

59

SLIDE 60

!"!# colliders working at Υ(4S) mass ) = 10.58 GeV
Large Λ1

" yields: ≈ 0.6 M at BaBar, ≈ 0.8 M at Belle

SELEX-like Ξ11

" signal not confirmed in Ξ11 " → Λ1 "6#7" decays

9/02/2018

8 =

9 :;;

< ×>?(:;;

< →@; <ABC<)

9(@;

<)

< 2.7×10#G (BaBar) 1.5×10#G (Belle) @ 95% CL

BaBar: PRD 74 (2006) 011103

SELEX Ξ11

"

Belle: PRL 97 (2006) 162001

SELEX Ξ11

"

ΔI(Ξ11

" − Λ1 ") GeV/c2

I(Λ1

"6#7") GeV/c2

Y. Gao, Spectroscopy at LHCb

Re Results fro rom Babar & Belle

60

SLIDE 61

A significant structure in right sign (RS) combinations: !"

#$%&#&#

Not present in wrong sign (WS) combinations: !"

#$%&#&%

Not observed for Λ"

# background candidates

Distributions similar except the peak in RS

9/02/2018

Y. Gao, Spectroscopy at LHCb

A significant peak!

Mass spectrum

61

LHCb-PAPER-2017-018 PRL 119 (2017) 112001

SLIDE 62

!"#$%(Ξ((

))) = ! Λ( )-./) − ! Λ( ) + !234 Λ( )

Studying Λ(

)-mass corrected mass:

ØSignal yield: 313 ± 33 ØResolution: 6.6 ± 0.8 MeV, consistent with simulated value ØLocal significance > 12>

9/02/2018

Y. Gao, Spectroscopy at LHCb

Fitting the mass peak

Systematic uncertainties

! Ξ((

)) = 3621.40 ± 0.72(stat) ± 0.27(syst) ± 0.14(Λ( )) MeV

! Ξ((

)) − !(Λ( )) = 1134.94 ± 0.72(stat) ± 0.27(syst) MeV

62

LHCb-PAPER-2017-018 PRL 119 (2017) 112001

SLIDE 63

See backup pages for references !"#$%(Ξ((

))) = ! Λ( )-./) − ! Λ( ) + !234 Λ( )

Studying Λ(

)-mass corrected mass:

ØSignal yield: 313 ± 33 ØResolution: 6.6 ± 0.8 MeV, consistent with simulated value ØLocal significance > 12>

9/02/2018

Y. Gao, Spectroscopy at LHCb

Fitting the mass peak

! Ξ((

)) = 3621.40 ± 0.72(stat) ± 0.27(syst) ± 0.14(Λ( )) MeV

! Ξ((

)) − !(Λ( )) = 1134.94 ± 0.72(stat) ± 0.27(syst) MeV

Value consistent with many theoretical calculations, especially LQCD

LHCb FGG

)) 63

LHCb-PAPER-2017-018 PRL 119 (2017) 112001

SLIDE 64

Signal peak presents in RUNI data sample with significance > 7#

9/02/2018

Y. Gao, Spectroscopy at LHCb

$ Ξ&&

'' → Λ& '*+,',' = 113 ± 21

Resolution: 6.6 ± 1.4 MeV 56 run I, run II = 0.8 ± 1.4 MeV

Consistent between two samples

Test with RUNI data

64

LHCb-PAPER-2017-018 PRL 119 (2017) 112001

SLIDE 65

Peaking structure remains significant (> 12%) after requiring minimum

decay time, ' > 5%). It is indeed a weak decay.

9/02/2018

Y. Gao, Spectroscopy at LHCb

Signal properties

65

LHCb-PAPER-2017-018 PRL 119 (2017) 112001

SLIDE 66

Large mass difference: !(Ξ$$

%%)LHCb − !(Ξ$$ % )SELEX = 103 ± 2 MeV

ØInconsistent with being isospin partners

Production: /(Ξ$$)//(Λ$

%) much smaller in LHCb result

9/02/2018

Y. Gao, Spectroscopy at LHCb

]

2

c ) [MeV/

++ cc

Ξ (

cand

m

3300 3400 3500 3600 3700 3800

2

c Candidates per 10 MeV/ 50 100 150 200 250 300 350

LHCb 13 TeV

SELEX Ξ$$

%

Comparison with SELEX

66 Hwang and Chung, PRD 78(2008) 073013; Brodsky et al., PLB 698 (2011) 251; Karliner and Rosener, arXiv: 1706.06961

LHCb-PAPER-2017-018 PRL 119 (2017) 112001

SLIDE 67

Tetraquark search ches in !"#±

D0

D0 announce ced a new state % &&'( ± → !"#±

si

significance of 5. 5.1*

ma

mass and nd widt dth

hi

high h pr produc duction n rate

+%

,- ≡ * // 0→%123456738 ×: %→!"

#±

* // 0→!"

123456738

;

,- =>>.

PRL 117 (2016) 022003

9/02/2018 67

Y. Gao, Spectroscopy at LHCb

SLIDE 68

Tetraquark search ches in !"#±

Up

Upper limits ts

LHCb-PAPER-2016-029 PRL 117 (2016) 152003

%&

'()* ≡ , -- → & + 01234516 ×8 & → !" 9#±

, -- → !"

9 + 01234516

:

'()* <==.

=

@ & @(!"

9) ×

C DEFG(&)

DEFG & = D & /D(!"

9)

9/02/2018

Y. Gao, Spectroscopy at LHCb

68

SLIDE 69

Tetraquark search ches in !"#

Us

Use similar selecti tion

n criteria as !$ → !"#,

, con

nsistent result
Si

Similar selection

n on
n !&#

9/02/2018

Y. Gao, Spectroscopy at LHCb

69

LHCb-PAPER-2016-029 PRL 117 (2016) 152003

SLIDE 70

Tetraquark search ches in !"#±

A

A ”con

ne cut” used in D0 analysis
NO

NOT us used ed in n the he LH LHCb an analy alysis is

D0, arXiv:1602.07588

9/02/2018 70

%& = ( !"

) − ( # + + - !" ) − -(#) + < ). 2

← w/o cone cut → ← w/ cone cut →

Y. Gao, Spectroscopy at LHCb

SLIDE 71

Tetraquark search ches in !"#±

Ve

Very large and clean !" sa sample at LH LHCb

Ad

Add a pion

n,

, no

peak ob
bserved at

t 5568 MeV

: 66k : 46k

Resolution on mass < 1MeV BW + poly bkg

%&

'()* = 8.6%

9/02/2018 71

Y. Gao, Spectroscopy at LHCb

LHCb-PAPER-2016-029 PRL 117 (2016) 152003

SLIDE 72

Mo Mode del inde ndepe pende ndent t ana nalysis

9/02/2018 72

2

2 mo models for !∗ → $%& co contributions based on PDG

Ex

Extended mod

del allo

allows all all LS couplin lings of eac each res esonan ance, e, an and in inclu lude e poorly ly motiv tivated ed states es → 146 146 pa parameters

Re

Reduced model us uses onl nly well motivated d states → 64 64 pa parameters

Oth

Other possib ibilitie ilities ch check cked, i incl cluding is isospin in vi violating decays of '∗( ’s ’s, adding two new !∗ st states with fre ree mass & width, no non-res esonance e contributions, …, …, wo would not change the conclusion à Co Confirm m th that t co conventional $%& co contributions ca cannot describe the da data, with h mini nimal assum umptions ns on n the heir spi pin, n, and nd no no assum umptions ns on n th their eir number er, shap apes es, mas asses es, wid idth ths, an and in inter erfer eren ence e patter erns.

Y. Gao, Spectroscopy at LHCb

SLIDE 73

Mo Mode del inde ndepe pende ndent t ana nalysis

Th

The method introduced by y Ba Babar, improved by y LH LHCb in in ! ""#$ % an analy alysis is à es essen entially a 2D Da Dalitz an analy alysis is

Sa

Same data set as amplitude analysis

LHCb-PAPER-2016-009 PRL 117 (2016) 082002

9/02/2018 73

Λ'

(

)

*/,

.)-

.*/,) .*/,- .)-

/

+ .*/,-

/

+ .*/,)

/

= .23

$

/ + .) / + .- / + .*/, /

.*/,-

/

, .)-

/

→ .)- , 789:2∗ LHCb .)-

/

.)-

/

Y. Gao, Spectroscopy at LHCb

SLIDE 74

Mo Mode del inde ndepe pende ndent t ana nalysis

Th

The distribution of !"#$%∗ as as a a fu functio ion of f '() ca can be dec decompo mposed ed as

Th

The unno unnorma malized ed Le Legendre m moment o

f r

rank * gi given by

Ge

Generally *+,- → ∞ 01 0!"#$%∗ ('()) = 5 6*

7

'() 6*(!"#$%∗)

*+,- *89

6*

7

'() = : 0!"#$%∗

; <;

6* !"#$%∗ 01 0!"#$%∗ '()

Eff. Corrected data

Legendre fun.

9/02/2018

Y. Gao, Spectroscopy at LHCb

74

LHCb-PAPER-2016-009 PRL 117 (2016) 082002

SLIDE 75

Mo Mode del inde ndepe pende ndent t ana nalysis

If

If onl nly !∗ → $% co contributions &'() ≤ +,'()

.
/012!∗ (4$%) = 7 8&

9

4$% 8&(/012!∗)

&'() &:;

9/02/2018 75

Λ=

>

$

,/@

% 4$% 4,/@$ 4,/@%

Determined by model & scattering data

the only model dependent part of the analysis
Y. Gao, Spectroscopy at LHCb

LHCb-PAPER-2016-009 PRL 117 (2016) 082002

SLIDE 76

Mo Mode del inde ndepe pende ndent t ana nalysis

If

If onl nly !∗ → $% co contributions &'() ≤ +,'()

Re

Resonances from ,/.%, ,/.$ ma may ha have e co contributions to higher orders 01 02345!∗ (7$%) = : ;&

<

7$% ;&(2345!∗)

&'() &=>

9/02/2018 76

Λ@

A

$

,/.

% 7$% 7,/.$ 7,/.%

Y. Gao, Spectroscopy at LHCb

LHCb-PAPER-2016-009 PRL 117 (2016) 082002

SLIDE 77

[GeV]

Kp

m

> / (44 MeV)

U l

< P

1.5 2 2.5

500

500 1000

l = 1

1.5 2 2.5

500

500 1000

l = 2

1.5 2 2.5

500

500 1000

l = 3

1.5 2 2.5

500

500 1000

l = 4

1.5 2 2.5

500

500 1000

l = 5

LHCb

1.5 2 2.5

500

500 1000

l = 6

1.5 2 2.5

500

500 1000

l = 7

1.5 2 2.5

500

500 1000

l = 8

1.5 2 2.5

500

500 1000

l = 9

1.5 2 2.5

500

500 1000

l = 10

1.5 2 2.5

500

500 1000

l = 11

1.5 2 2.5

500

500 1000

l = 12

[GeV]

p K

m >

U l

< P

1.5 2 2.5 50 100

3

10 ×

l = 1

1.5 2 2.5 50 100

3

10 ×

l = 2

1.5 2 2.5 50 100

3

10 ×

l = 3

1.5 2 2.5 50 100 10 ×

l = 4

1.5 2 2.5 50 100 10 ×

l = 5

simulations

*'s Λ

+

(4450)

c

P ,

+

(4380)

c

P

1.5 2 2.5 50 100 10 ×

l = 6

1.5 2 2.5 50 100 10 ×

l = 7

1.5 2 2.5 50 100 10 ×

l = 8

1.5 2 2.5 50 100 10 ×

l = 9

1.5 2 2.5 50 100 10 ×

l = 10

1.5 2 2.5 50 100 10 ×

l = 11

1.5 2 2.5 50 100 10 ×

l = 12

Mo Mode del inde ndepe pende ndent t ana nalysis

9/02/2018 77

Legendre moments from simulation & data

shaded region corresponding to !"#$ cutoff simulation data

Y. Gao, Spectroscopy at LHCb

LHCb-PAPER-2016-009 PRL 117 (2016) 082002

SLIDE 78

Mo Mode del inde ndepe pende ndent t ana nalysis

Co

Construct Hy Hypothesis fr from meas asured Legendre moments

!" :

: #∗ → &'( on

nly,

, ) ≤ )+,-

!/ ∶ allo

allow contrib ibutio ions fr from hig igh order moments up to 31 31

9/02/2018

Y. Gao, Spectroscopy at LHCb

78 [GeV]

p ψ J/

m 4 4.2 4.4 4.6 4.8 5 Yield / (20 MeV) 200 400 600 800 1000

LHCb

!" rejected at ~ 10 1

!" !/

LHCb-PAPER-2016-009 PRL 117 (2016) 082002