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

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

Ou Outline • In Intr trod oducti tion on t to sp o spec ectr trosc oscop opy 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

LHCb LHCb Detect ctor LHCb, Int. J. Mod. Phys. A30 (2015) 1530022 Fo Forward spectrometer running in pp collider • 2 < η < 5 range: ∼ 25% of b ¯ b pairs inside LHCb acceptance Excellent vertex and IP, decay time resolution: Hadron and Muon identification • * IP ≈ 20/0m for high- 2 3 tracks • O P→Q ≈ 95% for O S→Q ≈ 5% up to 100 GeV % → ;/=> and 9 : % → $ : ? @ A decays • * 4 ≈ 45/fs for 9 : • O T→T ≈ 97% for O S→T ≈ 1 − 3% Very good momentum resolution: Data good for analyses ⁄ • B2 2 ≈ 0.5% − 1% for 2 ∈ 0,200 /GeV • > 99% • * L M ≈ 24/MeV for two-body decays 9/02/2018 Y. Gao, Spectroscopy at LHCb 3

9/02/2018 Y. Gao, Spectroscopy at LHCb 4

Physics cs program at LHCb LHCb • Not o only 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 - ... ... 9/02/2018 Y. Gao, Spectroscopy at LHCb 5

Ex Experiment strategies • Advantage: h high p production r rates • Challenge: r reconstruct a an u unstable p particle f from O O(10 2 ) t tracks √ tr tracking → excellent m mass r resolution √ particle i identification Primary Vertex (PV) → no. o of c combinations r reduced √ Vertexin xing Secondary Vertex (SV) → weakly d decayed p particles → particles f from b b/c d decays 9/02/2018 Y. Gao, Spectroscopy at LHCb 6

Charmon Ch onia st studies at LH LHCb • At At LH LHCb ch charmonia ["" #] ma may be be acces essed ed by #] → '/)(→ + , + - ) + 0 - ["" '/) → + , + - 7 TeV 5.2 pb -1 LHCb-PAPER-2011-003 EPJC 71 (2011)1645 Primary Vertex (PV) Secondary Vertex (SV) 7 TeV 36 pb -1 1 "2,4 → '/) + 5 LHCb-PAPER-2011-019 PLB 714 (2012) 215 9/02/2018 Y. Gao, Spectroscopy at LHCb 7

Muo Muoni nic de decays of of ! "# an and ! "$ LHCb-PAPER-2017-036 PRL 119 (2017) 221801 st ob ! "#,$ → '/)* + * , • 1 st obser servati tion on of of • Co Competitive mass and width measurements 1.0 fb -1 7 TeV 2.0 fb -1 8 TeV ! "# 1.9 fb -1 13TeV ! "$ 9/02/2018 Y. Gao, Spectroscopy at LHCb 8

Ch Charmon onia st studies at LH LHCb • At At LH LHCb ch charmonia [%% +] ma may be be acces essed ed by +] → !/#(→ / 0 / 1 ) + 3 - [%% - %% + → 44 5 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 Primary Vertex (PV) 6 7 → $ % '( 3 = 9. ;; ± =. >9 ± =. ?@ ± =. >A 6 ×'= 1C Secondary Vertex (SV) � �� ����������� D $ % ('E) = =. F? ± =. =@ ± =. =; ± =. => D !/# ,6 HI E = A JKL = =. F@ ± =. '' ± =. =@ ± =. =; D !/# ,6 HI E = ; JKL 9/02/2018 Y. Gao, Spectroscopy at LHCb 9

m ! " → $$ %& " Ch Charmo monia from • Ex Exclu lusiv ive r reconstructio ion: c cle lean an s sam ample le, b better c control l of b of backg kgrou ound a and r resol esoluti tion on e effec ects ts ) = + ! " → (( ) & " ×+( (( ) → $$ %) LHCb-PAPER-2016-016 ' (( + ! " → //1& " ×+(//1 → $$ PLB 769 (2017) 305 %) ' 2 ( 34 = 5. 78 ± :. ;; ± :. :< ×5: =3 ' 1(;>>:) < 5:×5: =3 � �� ����������� ' @(;8>3) < :. 37 ×5: =3 1.0 fb -1 7 TeV 2.0 fb -1 8 TeV B //1 − B 2 ( 54 = 55:. 3 ± :. 7 ± :. < DEF B 1(34) − B 2 ( 34 = 73. 3 ± 5. > ± :. G DEF H 2 ( 54 = ;I. : ± 5. < ± 5. ; DEF 9/02/2018 Y. Gao, Spectroscopy at LHCb 10

Ch Charmon onia st studies at LH LHCb • At At LH LHCb ch charmonia ["" #] ma may be be acces essed ed by #] → '/)(→ + , + - ) + 0 - ["" - "" # → 11 2 - "" # → 33 LHCb-PAPER-2017-007 EPJC 77 (2017) 609 4 → "" # (→ 33) + 0 5 " (67) Primary Vertex (PV) 1.0 fb -1 7 TeV 2.0 fb -1 8 TeV 8 "6 8 "9 Secondary Vertex (SV) 8 ": 5 " (:7) 9/02/2018 Y. Gao, Spectroscopy at LHCb 11

Ch Charmo monia from m ! → ## + % • Al Allow to me measure product ction ratios R χ c 0 η c ( 1 S ) = 0 . 147 ± 0 . 023 ± 0 . 011 , R χ c 1 η c ( 1 S ) = 0 . 073 ± 0 . 016 ± 0 . 006 , C 2 ≡ B ( b → C 1 X ) × B ( C 1 → φ φ ) LHCb-PAPER-2017-007 R C 1 R χ c 2 η c ( 1 S ) = 0 . 081 ± 0 . 013 ± 0 . 005 , EPJC 77 (2017) 609 B ( b → C 2 X ) × B ( C 2 → φ φ ) R χ c 1 χ c 0 = 0 . 50 ± 0 . 11 ± 0 . 01 , � �� ��������������� & ' () → ## R χ c 2 χ c 0 = 0 . 56 ± 0 . 10 ± 0 . 01 , R η c ( 2 S ) η c ( 1 S ) = 0 . 040 ± 0 . 011 ± 0 . 004 , • Co Competitive measurements of masses of widths Γ η c (1 S ) [ MeV] Measured value World average [14] * → & ' + + 40 LHCb ∆ χ 2 = 4 - & ' → ,, M η c ( 1 S ) 2982 . 8 ± 1 . 0 ± 0 . 5 2983 . 4 ± 0 . 5 ∆ χ 2 = 1 35 3413 . 0 ± 1 . 9 ± 0 . 6 3414 . 75 ± 0 . 31 M χ c 0 M χ c 1 3508 . 4 ± 1 . 9 ± 0 . 7 3510 . 66 ± 0 . 07 ! → & ' + % 30 & ' → ## M χ c 2 3557 . 3 ± 1 . 7 ± 0 . 7 3556 . 20 ± 0 . 09 M η c ( 2 S ) 3636 . 4 ± 4 . 1 ± 0 . 7 3639 . 2 ± 1 . 2 This measurement 25 World average [14] � η c ( 1 S ) 31 . 4 ± 3 . 5 ± 2 . 0 31 . 8 ± 0 . 8 ,, → & ' + % Inclusive pp [15] 11 . 3 + 3 . 2 � η c ( 2 S ) – − 2 . 9 & ' → ,, - Exclusive [60] 20 2980 2982 2984 2986 2988 M η c (1 S ) [ MeV] 9/02/2018 Y. Gao, Spectroscopy at LHCb 12

(∗∗) sp ! "# spect ctrosc scopy • St Strange-ch charm states studied widely y to test QCD D models ∗ (?=G=) ! "# ∗ (>HI=) ! "# ∗ (>A==) ! "@ ∗ (>JA?) ! "> ! "@ (>J?I) ! "@ (>GI=) ∗ (>?@A) ! "= ∗ ! " St States observed from B-fa factories and other experiments ∗ , ! "= ∗ - ! " >?@A below DK threshold ! " States with unnatural spin-parity ( # B = = D , @ E , > D , … ) - 9/02/2018 Y. Gao, Spectroscopy at LHCb 13

(∗∗) sp ! "# spect ctrosc scopy • St Strange-ch charm states studied widely y to test QCD D models Inclusive KK → M E N O , M O N E + Q - LHCb-PAPER-2012-016 ∗ 2573 , M RX ∗ 2700 , M RZ ∗ (2860) JHEP 10 (2012) 151 ∗ (?=G=) M RS ! "# ∗ (>HI=) ! "# LHCb LHCb ∗ (>A==) ! "@ 2 (c) 2 (d) Candidates / 5 MeV/c 400 Candidates / 5 MeV/c 2000 1.0 fb -1 7 TeV ∗ (>JA?) ! "> 200 1000 ! "@ (>J?I) 0 0 ! "@ (>GI=) 2.5 3 2.5 3 + 0 2 + 0 2 D K invariant mass [GeV/c ] D K invariant mass [GeV/c ] S ∗ (>?@A) ! "= ∗ ! " States observed from B-fa St factories and other experiments ∗ , ! "= ∗ - ! " >?@A below DK threshold ! " States with unnatural spin-parity ( # B = = D , @ E , > D , … ) - 9/02/2018 Y. Gao, Spectroscopy at LHCb 14

(∗∗) sp ! "# spect ctrosc scopy • St Strange-ch charm states studied widely y to test QCD D models Inclusive KK → M E N O , M O N E + Q - LHCb-PAPER-2012-016 ∗ 2573 , M RX ∗ 2700 , M RZ ∗ (2860) JHEP 10 (2012) 151 ∗ (?=G=) M RS ! "# O → M ^ O N D _ E reveals ∗ (>HI=) ! "# - Dalitz plot analysis ] R ∗ 2860 , M R` ∗ (2860) ∗ (>A==) two states M RX ! "@ ∗ (>JA?) LHCb-PAPER-2014-035 LHCb-PAPER-2014-036 ! "> PRL 113 (2014) 162001 PRD 90 (2014) 072003 ! "@ (>J?I) ! "@ (>GI=) ∗ (>?@A) ! "= ∗ ! " States observed from B-fa St factories and other experiments ∗ , ! "= ∗ - ! " >?@A below DK threshold ! " States with unnatural spin-parity ( # B = = D , @ E , > D , … ) - 9/02/2018 Y. Gao, Spectroscopy at LHCb 15

���������������� % & ' ( ) * Da Dalitz tz plot t analysis ! " → $ LHCb-PAPER-2014-035 • ~11K K sign gnal events with purity 87% PRL 113 (2014) 162001 LHCb-PAPER-2014-036 PRD 90 (2014) 072003 1.0 fb -1 7 TeV 2.0 fb -1 8 TeV � �� ���������������������������������� 9/02/2018 Y. Gao, Spectroscopy at LHCb 16