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Heavy baryon spectrum new heavy exotics and isospin breaking Marek - - PowerPoint PPT Presentation

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Heavy baryon spectrum new heavy exotics and isospin breaking Marek Karliner with B. Keren-Zur, H.J. Lipkin, J. Rosner and N. Tornqvist Hadron 2011, Munchen, June 17, 2011 Outline spin-spin interaction between quarks color

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Marek Karliner with B. Keren-Zur, H.J. Lipkin, J. Rosner and N. Tornqvist

Hadron 2011, Munchen, June 17, 2011

Heavy baryon spectrum new heavy exotics and isospin breaking

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17 2

Outline

  • spin-spin interaction between quarks – “color magnetic”
  • same constituent quark masses in mesons and baryons
  • known baryons + mesons  predictions for

new heavy baryons: magnetic moments & masses

  • apps to heavy exotic QQqq mesons  predictions for Belle
  • Belle 5/2001: two Z_b(I=1) exotic mesons ~@ B+B*, B*+B*

 additional, more deeply bound states with I=0

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

Constituent Quark Models (CQM)

  • QCD describes hadrons as valence quarks

in a sea of gluons and q-qbar pairs.

  • at low E, χSB
  •  quark constituent mass
  • hadron can be considered as a bound

state of constituent quarks.

  • Sakharov-Zeldovich formula:
  • the binding & kinetic energies “swallowed”

by the constituent quarks masses.

=

i i

m M

3

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

Color Hyperfine (HF) interaction

  • 1st correction – color hyperfine

(chromo-magnetic) interaction

  • A contact interaction
  • Analogous to the EM hyperfine interaction –

a product of the magnetic moments.

  • In QCD, SU(3) generators take the place of

the electric charge.

 

( )

2

HF em

i j ij i j i j i j

V e r r m m           = 

 

 

 

     

j i j i j i j i ij QCD HF

r r m m v V    =    

 

 =

j i ij HF i i

V m M

4

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

Constituent Quark Model: caveat emptor

  • a low energy limit, phenomenological model
  • still awaiting derivation from QCD
  • far from providing a full explanation of the

hadronic spectrum, but it provides excellent predictions for mass splittings and magnetic moments

  • assumptions:
  • HF interaction considered as a perturbation
  •  does not change the wave function
  • same masses for quarks inside mesons and baryons.
  • no 3-body effects.

5

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

constituent quark mass ratios

  • example II:
  • extracting quark masses ratio:

 

 

 

 

s c c u c u s u s u D D K K

m m r m m v r m m v M M M M    =                 4 4

* *

  

  

 

 

 

 

             r m m v r m m v M M

s u s u K s u K s u s u s u K K

         =     =  4

* *

6

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

s u d color hyperfine splitting in baryons

  • The Σ (uds) baryon HF splitting:

– Σ*: total spin 3/2 - u and d at relative spin – 1 – Σ : isospin – 1

  • Symmetric under exchange of u and d
  • u and d at relative spin – 1
  • the „ud‟ pair does not contribute to the HF splitting

   

 = 

d u d u

       

*

 

 

   

ij s u s u

r m m v M M    = 

 

6

*

s u d

7

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

Quark mass ratio from HF splittings in mesons and baryons New type of mass relations with more heavy flavors

8

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

Similar relation for bottom baryons  prediction for mass 

(MK & Lipkin, hep-ph/0307243)

9

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10

new result from CDF at Hadron 2011: 193 MeV

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

also prediction for spin splitting between and

11

new result from CDF at Hadron 2011: 20 MeV

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Magnetic moments of heavy baryons

  •  mag. moments determined by s,c,b moments
  • quark mag. moments proportional to their

chromomagnetic moments DGG: (=EXP) 

challenge to EXP !

12

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

Predicting the mass of baryons

Q Q : Qsd or Qsu. (sd), (sd) in spin-0

 mass given by

Q

Can obtain (bsd) mass from (csd) + shift in HF:

13

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Hadron 2011, June 17

several options for obtaining from data: MeV MeV MeV

  • The Ξ (Qsq) baryons contain an s quark
  • Q mass differences depend on the spectator
  • optimal estimate from mesons which contain both s and Q:

Q

14

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baryons & exotics Hadron 2011, June 17 15

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  • M. Karliner, heavy

baryons & exotics Hadron 2011, June 17 17

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  • M. Karliner, heavy baryons & exotics

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Predictions for other bottom baryons

with B.Keren-Zur, H.J. Lipkin and J.L. Rosner

:

18

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17

Work in progress:

  • 19
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M.K. @DIS’09: “D0: Ω_b=6165 +/- 10 (stat) +/- 13(syst.) --- wrong”

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  • M. Karliner, heavy baryons

& exotics Hadron 2011, June 17

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  • M. Karliner, heavy baryons & exotics
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  • a menage a trois is very different from an ordinary family…
  • similarly, exotic hadrons with both q-q and q-qbar pairs

have important color-space correlations that are completely absent in ordinary mesons and baryons.

  • when both present, need to keep in mind that q-qbar

interaction is much stronger than q-q interaction color structures that are totally different from those in normal hadrons

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unusual experimental properties of (Q Q qbar qbar) and (Q Qbar q qbar) tetraquarks until 5/2011: leading tetraquark candidate: X(3872) Seen in With very high stats by Belle, BaBar and CDF M[X(3872)] = M(D) + M(D*) = 1865 + 2007 to within 1 MeV! b-quark analogue(s)? TH: for sufficiently heavy Q-s, tetraquarks might be below two meson threshold: (b qbar bbar q) below B Bbar (b qbar cbar q) below B Dbar

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  • M. Karliner, heavy

baryons & exotics Hadron 2011, June 17 27

crucial difference vs. ordinary mesons: can form a color configuration which has much stronger binding than some of these states have exotic electric charge, e.g.  their decays have striking experimental signatures: monoenergetic photons and/or pions, e.g. with I=0 above threshold can decay into via isospin violation,

  • r electromagnetically into 

both very narrow!

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  • M. Karliner, heavy baryons & exotics

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Unique signal for bbqq and bbq

double bottom baryons and bb tetratqaurks

_ _

  • b  c c s  J/ψ s

_ so bbq  J/ψ J/ψ (ssq)  J/ψ J/ψ Ξ similarly bbqq  J/ψ J/ψ (ssqq)  J/ψ J/ψ K K _ _ _ _ With all final state hadrons coming from the same vertex Unique signature but v. low rate. Challenge & opportunity for LHCb ! and bbqq __

28

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0802.0649 [hep-ph], Lipkin & M.K.: Enhancement due to mediation by tetraquark T_bb: B B*-bar  (b-bar b u dbar)

2008: Belle reported anomalously large BR (2 orders of mag.)

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Tornqvist, Z. Phys. C61,525 (1993): Heavy-light Qq mesons have I=1/2  they couple to pions  deuteron-like meson-meson bound states, “deusons” via pion exchange: (I=0) at threshold  X(3872) ! S-wave  I=1 attraction x3 weaker than I=0  no I=1 What about B B-bar* analogue ?... Alternative (complementary ?) desc. as “molecule”

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B B* vs D D*:

  • - same attractive potential
  • - much heavier, so smaller kinetic energy

 expect and I=1 states near threshold  seen by Belle !!! I=0 binding much stronger I=0 states expected 20-30 MeV below threshold EXP signature: Z_b(I=0)  (ns) + - Z_b(I=0)  B B-bar  via EM B*  B , E()=46 MeV  LHCb!

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  • M. Karliner, heavy baryons & exotics

Hadron 2011, June 17 36

_b

heavier, with I=1  stronger binding via   deuteron-like J=1, I=0 bound state: “beautron”

  • exp. signature:

(_b _b)  _b _b  

(_b) = 4.3+-3 MeV, (_b) = 9.2+-3 MeV so might be visible should be seen in lattice QCD

  • +

?

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  • consitituent quark model with color HF interaction

 _b, _b, _b masses predicted to  3MeV

  • challenge for theory: derivation from QCD
  • prediction:
  • QQqq tetraquarks: new color structures,

unique exp. signatures

  • prediction for peaks  just seen by Belle
  •  new I=0 exotic states below threshold:

BB*,B*B*, _b _b , …

Summary

  • M. Karliner, heavy baryons & exotics

37 Hadron 2011, June 17

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  • M. Karliner, heavy

baryons & exotics Hadron 2011, June 17

Backup slides

38

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  • M. Karliner, heavy baryons & exotics

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constituent quark mass differences

  • example I:

quark mass differences from baryon mass differences:

   =

            = = 

  ds HF us HF ud HF s d u dc HF uc HF ud HF c d u

V V V m m m V V V m m m M M

c

s c

m m  =

=

41

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difference of effective quark masses is the same in in mesons and baryons but depends on the spectator quark “how much you weigh depends

  • n who your neighbors are”

 challenge to npQCD

MK & Lipkin, hep-ph/0307243

  • M. Karliner, heavy baryons &

exotics

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  • M. Karliner, heavy baryons &

exotics Hadron 2011, June 17

Testing confining potentials through meson/baryon HF splitting ratio

  • B. Keren-Zur, hep-ph/0703011 & Ann. Phys
  • from constituent quarks model can derive:
  • depends only on the confinement potential

and quark mass ratio

  • can be used to test different confinement potentials

   

baryon s u meson s u K K

r r r r M M M M             =  

 

3 4

* *

43

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  • M. Karliner, heavy baryons &

exotics Hadron 2011, June 17

  • 3 measurements (Q = s,c,b)
  • 5 potentials:
  • Harmonic oscillator
  • Coulomb interaction
  • Linear potential
  • Linear + Coulomb
  • Logarithmic

Testing confining potentials through meson/baryon HF splitting ratio

44

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  • M. Karliner, heavy baryons &

exotics Hadron 2011, June 17

Hyperfine splitting ratio from potential models vs experiment

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Effective meson-baryon supersymmetry

  • meson: Q qbar

baryon: Q qq

  • in both cases: valence quark coupled to

light quark “brown muck” color antitriplet, either a light antiquark (S=1/2) or a light diquark (S=0,S=1)

  • Effective supersymmetry:
  • m( ) – m( ) independent of quark flavor (u,s,c,b) !

46

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  • M. Karliner, heavy baryons &

exotics Hadron 2011, June 17

  • for spin-zero diquarks:
  • need to first cancel the HF interaction contribution to meson masses:
  • for spin-one diquarks need to also cancel HF contribution

to baryon masses:

47

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Hadron 2011, June 17 48

  • M. Karliner, heavy baryons &
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  • M. Karliner, heavy baryons &

exotics Hadron 2011, June 17

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  • M. Karliner, heavy baryons &

exotics Hadron 2011, June 17

Summary of Ξ mass predictions

b

50