Heavy flavor hadron spectroscopy prospects at LHCb Tomasz Skwarnicki Syracuse University

(a few highlights rather than comprehensive review)

EF06: QCD and strong interactions: Hadronic structure and forward QCD Working group meeting June 24, 2020 Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 2 Colliders and bb rates 107 HL-LHC • Tremendous rate potential at hadron colliders CMS – background cross-sections are also large 6 ATLAS

) 10 • triggering is the major challenge

1 -

LS3 • hadron identification (p/K/p) helps bkg suppression LS5

5 LS4 LS1 10 LS2 LHCb – physics reach determined by detector LHCb LHCb Phase-II

hadron hadron colliders capabilities not by the machine Tevatron Upgrade 104 Upgrade • LHCb runs at diluted instantenous luminosity 푔푒표푚푒푡푟푖푐푎푙 CDF,D0

휀 • LHCb upgrades are detector rather than machine upgrades ℒ

ഥ 3 푏 10 • Collect all b-hadron species at the same time

푏 SuperKEKB (Belle II) 휎

– Spectroscopy of b-baryons and of Bc states which bb pairs produced (s pairs bb produced

colliders + - (within the angular acceptance) angular the (within 2 are out of reach of the 10 GeV e e factories, in addition

10 - e

(Belle) + to B, Bs spectroscopy 101 • Charm rates a factor of 10 higher than beauty (BaBar) rates:

0 GeV 10 e 10 – Prompt production as well as in b-quark decays (the 2000 2005 2010 2015 2020 2025 2030 2035 latter gives smaller backgrounds). – Also central-region production, heavy ion runs – Spectroscopy of charmed baryons and mesons න ℒ 푑푡 now CDF 10 fb-1 , D0 8 fb-1 – Doubly-charmed states! Doubly-beautiful states in the Run I Run II Run III Run IV Run V+VI future? LHCb 3 fb-1 6 fb-1 50 fb-1 300 fb-1 ATLAS,CMS 25 fb-1 450 fb-1 3000 fb-1 Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 3 LHCb detector • First hadron-collider experiment One-arm Muon detector optimized to heavy flavor physics: RICH 2 – Entire trigger bandwidth dedicated to it forward spectrometer – Main mission is search for BSM physics in CP violation and in rare decays of beauty and charm hadrons Dipole magnet RICH 1 – The same detector features make it also optimal for heavy flavor hadron spectroscopy • Forward spectrometer: – Similar b,c cross-section as for the central detectors, but in much smaller detection volume: • Factor of 10 cheaper than ATLAS/CMS • Less electronic channels, smaller event size, more affordable large trigger bandwidth to tape (Run II: 12 kHz, Run III >20 kHz)

• Can detect lower pT muons • Space for RICH detectors • Good hadron ID (missing in central detectors) • Some disadvantages relative to Belle II: – Limited 훾/휋0 detection. Will get worse in Run III. ECAL Major ECAL upgrade in the future? Vertex detector: Upstream Downstream – Lower absolute tracking efficiency HCAL (trigger only) Run I+II: strips Tracking: Tracking: – Often made up by higher production rates Run III: pixels strips Run I+II: straw tubes + inner strips • Trigger on muons and displaced Run III: fibers vertices: • LHCb Upgrade (in progress, Run III+IV): – Run I+II: hardware L0 trigger 40 MHz→1 MHz – Fully software trigger at 40 MHz; luminosity 4x1032 → 2x1033 cm-2s-1 ; 9 → 50 fb-1 readout to HLT – Finer segmentation of tracking detectors to deal with 5 times higher pile-up (1.5 → 7.6 visible interactions per crossing) – Run III: 40 MHz readout to HLT (allows increase • LHCb Upgrade Phase II (~2030, Run V+VI): of instantaneous luminosity) – Further luminosity upgrade; → 1-2 x1034 cm-2s-1 ; → 300 fb-1 – Need timing in tracking detectors and finer segmentation to deal with ~40 visible interactions per crossing Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 4 Conventional charmonium spectroscopy LHCb-PAPER-2019-005, JHEP 1907 (2019) 035

LHCb-PAPER-2017-036, PRL 119 (2017) 221801 + - + - cc1,2m m J/y, J/ym m Purely hadronic final states! 4.9 fb-1

-1 cc1 9 fb cc2

First observation of hadroproduction of y(3770) Best measurements of m,G for 3 3 (dominantly y(1 D1) state) cc2(2 P2) state The best world measurements of masses and widths of cc1,2

Detection of di-muon transition instead of g transition, a very promising method for high First observation of 3 statistics data samples in LHCb Upgrades I and II: y(1 D3) state! + - + - + - + - + - m m J/y,p p (m m J/y),m m Υ, m m Bc, …

푀 = 3842.71 ± 0.16 ± 0.12 푀푒푉 훤 = 2.79 ± 0.51 ± 0.35 푀푒푉 Expect a lot of interesting results in the future from studies of heavy meson-meson pairs (also heavy + − baryon-baryon pairs e.g. Λ푐 Λ푐 ) Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 5 Exotic charmonium spectroscopy: X(3872) -1 LHCb-PAPER-2013-001, PRL 110 (2013) 222001; 1 fb LHCb-PAPER-2014-008, NP B886 (2014) 665 110 (2013) 222001; 3 fb-1 -1 LHCb-PAPER-2015-015, PR D92 (2015) 011102; 3 fb B+X(3872)K+, + + 4.4sevidence for B X(3872)K , X(3872)y(2S)g X(3872)  y(2S) g , 1k + - X(3872)  J/y p p , y(2S)m+m- X(3872) J/ym+m- 3 fb-1 g detected in ECAL

Value of BR(X(3872)y(2S)g)/BR(X(3872)J/yg) important for X(3872) interpretations From angular correlations determine X(3872) JPC to be 1++ Not well determined and presently controversial

(crude projections by T.S.) LHCb-PAPER-2020-008, HbX(3872)…, arXiv:2005.13419 X(3872)  J/y p+p- , LHCb U. Phase Belle -1 + - 3 fb J/ym m I II II Decay mode 3 9 50 300 0.7 50 fb-1 fb-1 fb-1 fb-1 ab-1 ab-1 previously UL only

퐵+ → 퐾+푋 3872 1k 6k 33k 200k 0.17k 11k ( → 퐽/휓휋+휋−) 퐵+ → 퐾+푋 3872 36 0.2k 1k 7k 2k ( → 휓(2푆)훾) 퐵+ → 퐾+푋 3872 0.6k 2.7k 15k 90k 36 2k ( → 퐽/휓(1푆)훾) Future: coupled-channel analysis of the X(3872) lineshape including 퐷퐷ഥ∗ channel Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 6 ± Exotic charmonium spectroscopy: yf, yp states Example: LHCb-PAPER-2016-018,-019 LHCb X(4700)J/yf s PRL118, 022003 (2017) PRD95, 012002 (2017) 5.6 B+ J/yf K+,

X(4500)J/yf s

f K+K- ,J/ym+m-

6.1 s 3 fb-1

X(4274)J/yf 6.0 4.3k B+ J/yf K+

X(4140)J/yf s 8.4

X(4140) was previously observed by CDF,CMS,D0. Hints of X(4274) in CDF data.

± ± • Many puzzling structures observed in 퐵 → 푋 퐾, 푋 → J/yf, J/yp ,y(2S)p ,… • Conventional kaon excitations contribute to the same B decay modes • Amplitude analyses with larger statistics will help shed more light into their nature Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 7 Conventional heavy baryons • A lots of new states are being discovered. Many contain nice evidence for diquark substructure e.g. -1 **0 + - + - + LHCb-PAPER-2017-002, PRL 118 (2017) 182001; 3.3 fb Wc Xc K ,Xc pK p

Ξ퐷 s s s s s s s _ threshold u − 퐾 The narrow states q Ξ are likely 1P and 2S c c of c-(ss diquark) _ u _ s **0 q **0 Wc

W (3066) c

c (3090) c

(3050) W c

c c W (3119)

+ W c

Ξ (3000) W

푐 c 퐷

W MeV 0.4

± 1.3 MeV 1.3

OZI allowed but rips the diquark apart ± the diquark survives =3.5 G Wc(3188) ? =8.7 – fast fall apart (wide states)

– suppressed (narrow states) MeV 0.7

G

<2.6 MeV <2.6 <1.2 MeV <1.2

± G=60±19 MeV

G G -1

=4.5 LHCb-PAPER-2019-042, PRL 124 (2020) 082002; 9 fb G **0 Wb Future: X +sidebands Many more charm and beauty baryons to discover c

Study different decay modes of known baryons 0 + - Xb  Xc p Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 8 Exotic heavy baryons: pentaquarks -1 LHCb-PAPER-2015-029, PRL 115 (2015) 072001; 3 fb -1 LHCb-PAPER-2019-014, PRL 122 (2019) 222001; 9 fb 0 + - Lb Pc K , P + J/yp , 246k Λ푏 c signal events J/ym+m-

− − − 1 expected 1 , 3 2 P 2 2 J • First undisputed observation of pentaquark states – The latest results seem to favor loosely-bound meson-baryon substructure (∗) + (퐷ഥ Σ푐 ), but much more work is needed to establish their internal dynamics • Some of future work: – JP determination from data (∗) +∗ – 퐷ഥ Σ푐 states also expected and should be relatively narrow + – Are there also wide Pc states as the 2015 amplitude analysis suggested? – Are these states also produced in Cabibbo suppressed process: 0 + - Lb Pc p ? – Decays to open charm particles? – Isospin partners? + – Strange partners e.g. Pcs  J/yL ?

(∗) + Masses expected near 퐷ഥ Σ푐 thresholds Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 9 Doubly flavored baryons and tetraquarks tetraquark baryon d c c u c c LHCb-PAPER-2017-018, LHCb PRL 119 (2017) 112001 u + pK- + Lc  p + 1.7 fb-1 The lightest 1 state

Karliner,Rosner PRL 119, 202001 (2017) the same toolkit Eighten, Quigg PRL 119, 202002 (2017) See also: Esposito,Papinutto,Pilloni,Polosa,Tantalo PRD88, 054029 (2013) Stable tetraquark, will decay weakly

Karliner,Rosner PRD90,094007 (2014)

Consistent results predicted by LQCD: Francis,Hudspith,Lewis,Maltman PRL 1118,142001 (2017) Future searches for such states above or below the 푄푞ത 푄푞ത threshold will be very exciting Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 10 Doubly hidden-charm tetraquark? LHCb-PAPER-2020-011 in preparation + - + - Preliminary results shown at CERN seminar 푇푐푐푐ҧ 푐ҧ  J/yJ/y(m m )(m m ) Liupan An, June 16, 2020, 9 fb-1

34k J/yJ/y

• Very significant structure in J/yJ/ymass is observed • Interpretation is not clear: – one or more interfering resonances (diquark substructure?)

– possible effects due to nearby cc0cc0,1 thresholds

This discovery opens a new chapter in heavy flavor hadron spectroscopy to be written by future measurements Heavy flavor hadron spectroscopy, LHCb, EF06 meeting Tomasz Skwarnicki, 6/24/20 11 Summary • LHC offers enormous rates of heavy quarks via hadronic production cross-sections and large instantaneous luminosity • Good place to study hadron spectroscopy with heavy quarks, including multi-quark exotics • LHCb is well suited for such studies, thanks to hadron ID and large trigger bandwidth devoted to heavy flavors – Several ground-breaking discoveries (J/yp pentaquarks, doubly-charmed baryons, very recently J/yJ/ystates) • Near and farther future upgrades of the LHCb detector to take better advantage of the opportunity offered by the LHC