Heavy Spectroscopy

Ken Moats Carleton University (Oawa, Canada)

Physics in Collision XXXV University of Warwick Sept 17, 2015 Outline

• Spectroscopy • Convenonal Spectroscopy • Open Charm • Open Boom • Charmonium • Boomonium • Exoc Meson Spectroscopy • XYZ • • Summary

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 1 Spectroscopy

• : colour-neutral systems of and (QCD) • : Building blocks of ordinary maer ((qqq) p, n, …) • Mesons ( q : Simplest quark bound states and the best benchmark to q ) understand how quarks interact to form hadrons • €Exocs : unconvenonal quark- configuraons € • Spectroscopy is the key to understanding properes of hadrons and QCD • What are the internal structure and degrees of freedom of hadrons? • What is the role of gluons? • What is the origin of quark confinement? • Are andqq qqq the only possible configuraons?

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 2 € € Meson Spectroscopy

• Goals: • Invesgate fundamental aspects of QCD • Study meson spectrum and decays • Search for new/exoc states • Complement Lace QCD calculaons [See Talk by Chrisne Davies]

• Light quark (uds) mesons: • Sensive to chiral symmetry breaking and vacuum condensate effects • Probe QCD at larger distances (confinement)

• Heavy quark (cb) mesons: • Can be described by non-relavisc potenal models • Probe QCD at shorter distances where gluon exchange dominates

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 3 Convenonal Meson Spectroscopy

• Meson Quantum Numbers characterized by a given JPC

• For given spin and orbital angular momentum and radial excitaons, generate our known spectrum of mesons

Allowed: Not allowed: exoc combinaons: JPC = 0-+ 1–- 1+- 0++ 1++ 2++ … JPC = 0-- 0+- 1-+ 2+- …

Constuent :

Lorentz vector 1- Scalar Linear gluon exchange confining at short distance potenal [Godfrey, Isgur, PRD 32, 189 (1985)] K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 4 Convenonal Meson Spectroscopy

• Relavisc correcons implicitly included in spin-dependent terms

Spin-spin interacons: Spectroscopic Notaon: 2S+1 n LJ 3 1 S1 1S

1 1 S0 Spin-orbit interacons: 13P 1P 2 3 1 P1

3 1 P0

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 5 Lace QCD vs. Constuent Quark Model

Wurtz, Lewis, Woloshyn, arXiv:1409.7103 Godfrey, KM, arXiv:1507.00024

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 6 Experiments

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 7 Open Charm Mesons

cq where q = (u,d,s)

• Interest in Open Charm: • Strong Interacons: QCD, strong decay modes, intermediate case € between heavy and light quarks, interesng spectroscopy • In heavy quark limit (mQ → ∞), dynamics is governed by the light quarks and gives rise to heavy quark symmetry • Weak Interacons: complement measurements with b quarks, mixing, CP violaon, possible window to BSM physics

• Charm Spectrum predicted in 1985 [Godfrey, Isgur, PRD 32, 189 (1985)], updated in 2001 [Di Pierro, Eichten, PRD 64, 114004 (2001)]

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 8 Charm-Strange Mesons: 1S

Ds(cs ) D (3040) ! sJ 1S states are well known: • Below DK threshold ! DsJ(2860) • Narrow widths ! D (2700) € • Measured m, Γ agree with s1 constuent quark models ! Ds2(2573) Ds1(2536) ! ! Ds1(2460)

! Ds0(2317) Observaon of excited states over

the past decade has sparked * ! Ds renewed interest in open charm ! ! Ds

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 Figure from [Zghiche, arXiv: 0710.0314] 9 Charm-Strange Mesons: 1P

• 1P states well measured by Belle [PRD 69, 112002 (2004)], BaBar [PRD 79, 112004 (2009)], [PRD82, 111101 (2010)] and LHCb [JHEP 109, 145 (2013)] D (3040) ! sJ 3 • Ds2(2573) confirmed as 1 P2

[LHCb, PRD90, 072003 (2014)] ! DsJ(2860)

! Ds1(2700) ! D (2573) D (2536) ! s2 __ J=2 s1 ! D (2460) __ J=0 s1

! Ds0(2317)

* ! Ds ! ! Ds

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 10 Charm-Strange Mesons: 1P

* Ds0(2317) and Ds1(2460) lighter and narrower than predicted, below DK and D K threshold, and decaying to D π and D *π s s D (3040) [BaBar, PRL 90, 242001 (2003)] [CLEO, PRD 68, 032002 (2003)] ! sJ

• In heavy quark limit (mQ → ∞): ! DsJ(2860) JP = 1+ , 2+ doublet: ! Ds1(2700) jq = 3/2, decays via D-wave ! Ds2(2573) Ds1(2536) ! JP = 0+ , 1+ doublet: ! Ds1(2460)

jq = 1/2, decays via S-wave ! Ds0(2317)

May be explained by coupled-channel effects: * ! Ds (*) Strong S-wave coupling and proximity to D K thresholds, shis the masses of ! ! Ds the jq = 1/2 states below threshold [van Beveren, Rupp, PRL 91, 012003 (2003)]

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 11 Charm-Strange Mesons: Ds1(2700)

• Ds1(2700), DsJ(2860) and DsJ(3040) mesons observed by Belle and BaBar [PRL 97, 222001 (2006)], [PRL 100, 092001 (2008)], [PRD 80, 092003 (2009)] D (3040) ! sJ Ds1(2700):

! DsJ(2860)

! Ds1(2700)

! Ds2(2573) 3 Ds1(2536) ! • Can be explained as 2 S1 state 3 ! Ds1(2460) with small 1 D1 component

! Ds0(2317) • Mixing angle ~10° gives central value of the measured * ! Ds rao. D ! [Godfrey, KM, PRD 90, 117501 (2014)] ! s

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 12 Charm-Strange Mesons: DsJ(2860)

[BaBar, PRD80, 092003 (2009)]

D (3040) ! sJ Overlapping spin-1 and spin-3 resonances at 2860 MeV observed D (2860) by LHCb [PRL 113, 162001 (2014)], ! sJ [PRD 90, 072003 (2014)] 3 3 ! Ds1(2700) Idenfied as 1 D1 and 1 D3 states ! Ds2(2573) Ds1(2536) ! ! Ds1(2460)

! Ds0(2317)

* ! Ds ! ! Ds

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 13 Charm-Strange Mesons: Ds2 and Ds2’

J=2 D-wave states yet to be observed D (3040) ! sJ

! DsJ(2860)

! Ds1(2700)

! Ds2(2573) Ds1(2536) ! ! Ds1(2460)

! Ds0(2317)

* ! Ds ! [Godfrey, KM, PRD 90, 117501 (2014)] ! Ds

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 14 Charm-Strange Mesons: DsJ(3040)

DsJ(3040): D (3040) • Only seen in D*K final state, ! sJ implying unnatural parity (0-, 1+, 2-, 3+, 4-, etc…) ! DsJ(2860) • Likely a J=1 2P state, but further study needed to confirm ! Ds1(2700)

! Ds2(2573) Ds1(2536) ! ! D (2460) s1 6σ

! Ds0(2317)

* ! Ds ! [Godfrey, KM, preliminary] ! Ds [BaBar, PRD 80, 092003 (2009)] K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 15 Charm-Strange Mesons

Observed States

Many excited states require further study [Godfrey, Isgur, PRD 32, 189 (1985)] [Godfrey, KM, preliminary]

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 16 Charm Mesons D(cq ) q = u,d

€ _____ Godfrey, Isgur, Predicons PRD 32, 189 (1985) PDG generally BaBar agree LHCb with D0(2400), D2(2460), DJ(2760) recently observed experiment in at LHCb [PRD 91, 092002 (2015)]

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 17 D0(2400), D2(2460), DJ(2760)

LHCb Amplitude analysis of [PRD 91, 092002 (2015)]

D2(2460): DJ(2760): confirmed as J=2 1P state confirmed as J=1 1D state

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 18 Open Boom

B(bq ) where q = (u,d) spectrum

Bs(bs ) € • Low energy peaks well established. Improved m, Γ measurements of € 1P states in Bπ and B*π decays:

[LHCb, JHEP 1504, 024 (2015)]

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 19 Open Boom

Observaon of BJ(5840) and BJ(5960)

+ - B π , 0.5 < pT(π) < 1.0 GeV

[LHCb, JHEP 1504, 024 (2015)] One Peak Hypothesis: 9.6σ (4.8σ) for B+π- (B0π+) Masses and widths Extensive studies of charm Two Peak Hypothesis: consistent with and beauty meson properes 7.5σ (4.6σ) for B+π- (B0π+) 1 3 to appear soon B(2 S0) and B(2 S1) [Godfrey, Swanson, KM] K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 20 Charmonium

• Powerful tool for understanding QCD

• High c quark mass (mc ~ 1.5 GeV) makes it plausible to use non-relavisc potenal models

• Quark potenal models extremely successful in describing charmonium spectrum

• A number of states above DD [Jingzhi Zhang, Charm 2013, Manchester] threshold are not well-described by convenonal quark models

• Serious gap in our understanding of these exoc states € (more on these later)

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 21 Boomonium

• Non-relavisc system (mb ~ 5 GeV) Good test of non-relavisc potenal models • LHC and e+e- colliders can discover missing excited boomonium states 3 • 3 P1 state was first parcle discovered at LHC [ATLAS, PRL 108, 152001 (2012)], later confirmed by LHCb [LHCb-CONF-2012-020] 3P

γ 2P 1P 2S γ 2P 1P γ 3P γ 1S γ

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 [PRL 108, 152001 (2012)] 22 Boomonium

BB

€

3 • 3 PJ states near threshold, so couplings to virtual BB BB pairs could affect masses and decay properes wrt pure states bb [Ferre, Galata, PRD 90, 054010 (2014)] • 33P could have substanal component of BB * 1 € [Karliner€ Rosner, PRD 91, 014014 (2015)] Observed states €

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 € 23 Boomonium

BB

€

• Improved LHCb mass measurement [JHEP 10, 088 (2014)]

• Good agreement with potenal model calculaons. Coupled channel effects small

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 24 Search Strategies

• LHC Run II and Belle II offer possibility of observing more states • Want to study decays of boomonium mesons to propose search strategies

• Based on rescaling LHCb event numbers: • Expect producon cross secon to roughly double going from 8 to 13 TeV • Expect order of magnitude increase in luminosity

• Focus on states below threshold ( ) BB • Relavely narrow widths and high BR via radiave transions • Producon of high L states suppressed: €

• Focus on radiave transions • Cleaner backgrounds and easier to reconstruct than hadronic decays

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 25 Search Strategies: 3S states

8 8 pp: LHCb 13 TeV, producing 3.1 × 10 ϒ(3S), 1.4 × 10 ηb(3S) e+e-: Belle II, producing 109 ϒ(3S), assuming 250 -1

Interested in ϒ(3S) decay chains via unobserved 1D states

Interested in

ηb(3S)

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 [Godfrey, KM, arXiv:1507.00024] 26 Search Strategies: 3P states

6 3 6 1 LHCb 13 TeV, producing 7.9 × 10 χb(3 P1) and 7.3 × 10 hb(3 P1)

Large event rate 3 for 3 P1. Not surprising it was discovered first in LHC Run 1

1 Missing 3 P1 state may be observed via hadronic decays, depending on reconstrucon efficiency K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 [Godfrey, KM, arXiv:1507.00024] 27 Search Strategies: 4P & 5P states

6 3 6 3 6 3 LHCb 13 TeV, producing 9.7 × 10 4 P2 , 7.4 × 10 4 P1 , 3.1 × 10 4 P0 6 3 6 3 6 3 8.2 × 10 5 P2 , 5.7 × 10 5 P1 , 2.2 × 10 5 P0 Above threshold, so small BB radiave BR. Not possible to observe at LHC Run I € Possible to observe some 4P states in simple γµ+µ- final states at LHC Run II

3 May even be able to see the 5 P2 state

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 [Godfrey, KM, arXiv:1507.00024] 28 Exoc X, Y, Z states

[M. Nielsen, Charm 2010]

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 29 Exoc X, Y, Z states

Charmonium-like (cc ) Boomonium-like (bb ) 16 neutral & 7 charged 1 neutral & 2 charged

€ €

[Olsen, Front. Phys. 10, 101410 (2015)] K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 30 Exoc Meson Spectroscopy

Many possibilities and models to describe these states:

• Conventional

• Hybrids • States with excited gluonic degrees of freedom

• Multiquark States • Compact • Molecular state • -onium Tetraquark

• Threshold-effects Rescattering near threshold due to interactions between two outgoing mesons

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 31 Compact Tetraquark

• Spaally compact object

• expect flavour mulplet of states

• Expect to fall apart into meson + meson unless mass is below threshold

• Therefore XYZ states above threshold cannot be compact unless more complicated interacons

• Can the Born-Oppenheimer approach be used but with gluons replaced with light quarks?

[Braaten, PRL 111, 162003 (2013)]

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 32 Meson Molecule

• If states are close to threshold can bind into loosely bound molecule

• Constuents must be narrow (long lived)

• Many XYZ mesons are near a charm meson threshold

I this just a coincidence?

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 33 X(3872)

First observed by Belle [PRL 91, 262001 (2003)] ψ’ Confirmed by: CDF [PRL 93, 072001 (2004)] D0 [PRL 93, 162002 (2004)] BaBar [PRD 71, 071103 (2005)] X(3872)

M = 3872.0 ± 0.6 ± 0.5 MeV Γ < 1.2 MeV at 90% C.L. consistent with detector resoluon. • X(3872) → γJ/ψ implies C = + [Belle, hep-ex/0505037], [BaBar, PRD 74, 071101 (2006)]

Angular distribuons imply JPC = 1++ LHCb [PRL 110, 222001 (2013), PRD 92, 011102 (2015)]

• seen [Belle, PRL 97, 162002 (2006)] • seen [BaBar, PRD 77, 011102R (2008)]

• Implies decays predominantly to K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 34 X(3872) as a D0D*0 molecule

• Close to D0D*0 threshold so consistent [Close, Page PLB 578, 119 (2004)] 0 *0 “ ” [Voloshin PLB 579, 316(2004)] with S-wave D D molecule [Swanson PLB 588, 189(2004)] • consistent with JPC = 1++ [Braaten, Kusunoki PRD 72, 054022 (2005)]

X(3872) is considered to be D0D*0 molecule but decays X(3872) → γJ/ψ & X(3872) → γψ’ imply ccbar content

[LHCb-PAPER-2014-008]

[Skwarnicki, Moriond QCD 2015] 3 Mixing with χ’c1 explains X(3872) properes as admixtures of molecule and 2 P1 states

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 35 Z± (4430)

Z±(4430) in [PRL 100, 142001 (2008)]

• Charged state cannot be confused with charmonium (first observed state of that type by Belle)

• JP = 1+ preferred by > 9.7σ [LHCb, PRL 112, 222002 (2014)] • Amplitude analysis consistent with Breit-Wigner resonance data BW • Possibly a D D(2S) molecule [Ma et. al., PRD 90, 037502 (2014)] [Barnes, Close, Swanson, PRD 91, 014004 (2015)]

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 36 Pentaquarks

• LHCb observed resonances in the decays: [PRL 115, 072001 (2015)]

* - + Expected resonances: Λ -> K p Unexpected structure: Pc -> J/Ψ p

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 37 Pentaquarks

Fit requires 2 resonances: + + Pc(4380) Pc(4450)

Significance: 9 σ 12 σ Best fit JP : 3/2- 5/2+

+ + Pc(4450) Pc(4380)

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 38 Pentaquarks

+ + Pc(4450) Pc(4380) phase change is consistent inconclusive with that of a resonance

BW BW

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 39 Interpretaon of the Pentaquarks

cc uud

Several models to explain quantum numbers and binding mechanism Recent review: [Burns, arXiv:1509.02460]

€

Best Fit JP

Note that the states lie near several kinemac thresholds.

[Burns, arXiv:1509.02460] K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 40 Interpretaon of the Pentaquarks

Rescaering with χc1 p : (cc )(uud ) [Guo et. al., arXiv:1507.04950]

(*)+ (*)0 Molecular states: Σc D : (cud)(uc ) [Karliner€, Rosner , arXiv:1506.06386]

Different decays in each scenario, depending on isospin and angular €momentum assignments [Burns, arXiv:1509.02460] Diquark-antriquark: (c ud )(uc) [Lebed, arXiv:1507.05867] Pc Partner states not yet observed S-waves: Further study is needed P-waves: € with LHC Run II data to K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 disnguish models 41 Summary

• In the last decade, many hadrons with heavy quarks have been observed with properes in good agreement with theory (convenonal states)

• Many new states observed which pose a big challenge to our understanding of the QCD spectrum • Some are strong candidates for and hybrids (i.e. X(3872), Z(4430)+)

• Coupled channel effects not fully understood (i.e. Ds(2317) & Ds(2460)) • Recently observed pentaquark states need further study

• No single model gives a consistent descripon of all states. Lots of interesng work to be done

• Very interesng future with many new experiments: Belle II, LHC Run II, etc… Need theorecal predicons to idenfy promising searches

K. Moats, Carleton University Heavy Quark Spectroscopy, PIC 2015 42