Microscopic Model of Charmonium Strong Decays

Transcription

1 Microscopic Model of Charmonium Strong Decays J. Segovia, D.R. Entem and F. Fernández The XIV International Conference on Hadron Spectroscopy (Hadron 2011) München, 13-17th of June 2011 University of Salamanca Spain

2 Contents Introduction 1 Introduction

3 1.- Introduction Introduction A rather poorly understood area in hadronic physics Renew interest of charmonium discovery of XYZ mesons performed by B factories One open topic: strong decays of c c states Poorly understood area: Is difficult to solve problems within QCD non-perturbative regime Much of our knowledge of strong interaction comes from strong decays Open-flavor strong decays are mediated by q q pair production. Several phenomenological models have been developed to deal with this topic The relation of the phenomenological models to QCD microscopic decay mechanism has not been established

4 How to deal with it 3 P 0 MODEL The q q pair is created from the vacuum J PC = 0 ++ The created q q pair together with the q q pair in the original meson regroups in the two outgoing mesons via a quark rearrangement process OZI rule FLUX-TUBE MODEL Similar to 3 P 0 model Takes into account the dynamics of the flux-tubes by including the overlaps of the flux-tube of the initial meson with those of the two outgoing mesons. MICROSCOPIC MODEL The strong decays are driven by interquark Hamiltonian which determines the spectrum

5 Reference works on microscopic decay model Little previous work in this area Charmonium: The model and Charmonium: Comparison with experiment E. Eichten, K. Gottfried, T. Kinoshita, K.D. Lane and T.-M. Yan Phys. Rev. D (1978); (1980) Main features: Assume q q pair production from the static vector linear confining interaction The c c wave functions are those coming from the model except for the open-charm meson wave functions which are approximated by gaussians Comments about results: Very early theoretical study of c c states There is an update Phys. Rev. D (2006) Predicted partial and total widths of ψ(3770), ψ(4040) and ψ(4160)

6 Reference works on microscopic decay model (Continuation) On the mechanism of open-flavor strong decays E.S. Ackleh, T. Barnes and E.S. Swanson Phys. Rev. D 54, 6811 (1996) Main features: Assume q q pair production from the scalar linear confining interaction and One-Gluon Exchange (OGE) Meson wave functions as SHO wave functions Analytical decay rates Comments about results: Overall scale of the total decay amplitudes is too large 8 ( Choice of model parameters NOT DUE >< Wave function approximation 8 The discrepancy may be >< Non-relativistic reduction of amplitudes POSSIBLY DUE Assumption of scalar linear potential >: >: Disregard a possible constant It would be interesting to apply these microscopic decay calculations to charmonium because the transverse OGE should be much smaller

7 E.S. Ackleh et al. E. Eichten et al. J. Segovia et al. Framework Non-relativistic Non-relativistic Non-relativistic Kernel Scalar linear + OGE Static linear Vector-scalar (screened + cte) + OGE W.F. SHO Exact + SHO Exact solutions Coupled No Yes No Phase-Space Relativistic Relativistic Relativistic Application Some light meson decays Open-charm decays of c c Open-charm decays of c c Very recent works Yu.A. Simonov arxiv: v1 [hep-ph] 21 Mar 2011 Bao-Fei Li et al. arxiv: v1 [hep-ph] 9 May 2011

8 Main features Spontaneous chiral symmetry breaking (Goldstone-Bosons exchange): L = ψ (iγ µ µ MU γ 5) ψ U γ 5 = 1 + i γ f 5 λ a π a 1 π 2fπ 2 π a π a +... M(q 2 ) = m `q 2 h i qf = m Λ 2 1/2 q Λ 2 +q 2 QCD perturbative effects (One-Gluon Exchange): Confinement: Screened potential: 8 < : L = i 4πα s ψγµg µ λ c ψ V CON = a sv scalar CON + (1 as)v vector CON V C CON ( r ij) = ˆ a c(1 e µcr ij ) + ( λ c i λ c j ) V C CON ( r ij) = ` a cµ cr ij + ( λ c i λ c j ) r ij 0 V C CON ( r ij) = ( a c + )( λ c i λ c j ) r ij

9 Some recent applications N-N interaction D.R. Entem, F. Fernández and A. Valcarce, Phys. Rev. C 62, (2000) B. Julia-Diaz, J. Haidenbauer, A. Valcarce and F. Fernández, Phys. Rev. C 65, (2002) Baryon spectrum H. Garcilazo, A. Valcarce and F. Fernández, Phys. Rev. C 63, (2001) H. Garcilazo, A. Valcarce and F. Fernández, Phys. Rev. C 64, (2001) Meson spectrum J. Vijande, A. Valcarce and F. Fernández, J. Phys. G 31, 481 (2005) J. Segovia, D.R. Entem and F. Fernández, Phys. Rev. D (2008) J. Segovia, D.R. Entem and F. Fernández, accepted by Phys. Rev. D Molecular states P. G. Ortega, J. Segovia, D. R. Entem and F. Fernández, Phys. Rev. D 81, (2010)

10 Some recent applications (Continuation) Deuteron CQM NijmII Bonn B Exp. ǫ d (MeV) P D (%) Q d (fm 2 ) ± A S (fm 1/2 ) ± A D /A S ± Charmonium reactions σ (nb) (a) Number of events/2.5 MeV X(3872) (a) Light mesons M(D 0 D *- π + ) (GeV/c 2 ) M(J/ψπ + π - ) (MeV) M(MeV) M(MeV) η ω h 1 f 0 f 1 f 2 ω 2 ω 3 η 2 h 3 f 3 f 4 η 4 ω M(D 0 D - π + ) (GeV/c 2 ) π ρ b 1 a 0 a 1 a 2 ρ 2 ρ 3 π 2 b 3 a 3 a 4 π 4 ρ 4 σ (nb) (b) Number of events/5 MeV 70 (b) M(J/ψπ + π - ) (MeV)

11 Model parameters Quark masses m c (MeV) 1763 Confinement a c (MeV) µ c (fm 1 ) (MeV) a s 0.81 One-gluon exchange α Λ 0 (fm 1 ) µ 0 (MeV) ˆr 0 (fm) ˆr g (fm) J. Vijande et al. J. Phys. G (2005)

12 Charmonium (nl) States M CQM M EXP Γ e+ e CQM Γ e+ e EXP (1S) J/ψ ± ± 0.14 (2S) ψ(2s) ± ± 0.05 (1D) ψ(3770) ± ± 0.05 X(4008) 4008 ± 40 (3S) ψ(4040) ± ± 0.20 (2D) ψ(4160) ± ± 0.22 X(4260) 4260 ± 10 (4S) X(4360) ± (3D) ψ(4415) ± ± 0.12 (5S) X(4630) (4D) X(4660) ± 11 ± J. Segovia, D. R. Entem and F. Fernández, Phys. Rev. D 78, (2008)

13 Contribution diagrams and interaction Hamiltonian δ ǫ B δ ǫ B A α β λ ρ C A α β λ ρ C δ ǫ B δ ǫ B A α β λ ρ C A α β λ ρ C H I = 1 2 Z d 3 xd 3 y J a ( x)k( x y )J a ( y)

14 Currents and Kernels Currents are assumed to be a color octet. When the color dependence λ a /2 is factored out they are given by 8 >< ψ( x)iψ( x) Scalar Lorentz structure J( x) = ψ( x)γψ( x) = ψ( x)γ >: 0 ψ( x) Static term of vector Lorentz structure ψ( x) γψ( x) Spatial term of vector Lorentz structure Kernels 8 4 ˆ a c(1 e µcr ) + >< +4 ˆ a c(1 e µcr ) + K(r) = 4 ˆ a c(1 e µcr ) + + >: αs r αs r Notation 8 >< sks JKJ decay model j >: 0 Kj 0 j T Kj T Scalar confining interaction Static vector confining interaction Transversal vector confining interaction Color Coulomb OGE Transverse OGE

15 Some Formulas Γ A BC = 2π E BE C M A k 0 X J BC,l M A BC (k 0 ;J BC,l) 2 M A BC = M A BC + ( 1) I B+I C I A +J B +J C J BC +l M A CB M A BC = I color I flavor (I signature I spin space ) Color term Flavor term I color = X a» λ a Tr 2 λ a = j ff I flavor = ( 1) tα+t β+i A tβ I δ fαfδ δ fβ f ρ δ fµfλ δ fνfǫ q(2i B + 1)(2I C + 1)(2t µ + 1) C t µ I B t α I A

16 Some Formulas (Continuation) Spin-space term Z 2 X I spin space = d 3 K B d 3 K C J BC M BC lm J A M A δ (3) ( K K 0 )δ(k k 0 ) 1 + δbc m,m BC Y lm (ˆk) X Z J B M B J C M C J BC M BC d 3 p δ d 3 p ǫd 3 p λ d 3 p ρ δ (3) ( K B P B ) k M B,M C δ (3) ( K C P C )φ B ( p B )φ C ( p C )δ ρβ δ (3) ( p ρ p β )δ (3) ( p λ + p ǫ + p δ p α) K( p λ + p ǫ ) lim [ū λ( p λ )Γv ǫ( p ǫ)] lim [ū δ( p δ )Γu α( p α)] v/c 0 v/c 0 Z d 3 p αd 3 p β δ (3) ( P A )φ A ( p A )

17 The 3 P 0 model Z H I = g d 3 x ψ( x) ψ( x) Color term I color = 1 3 Flavor term j ff I flavor = ( 1) tα+t β +I Aδ fαfδ δ fβ fρ δ tβ I fµf λ δ fν fǫ q(2i B + 1)(2I C + 1)(2t µ + 1) C t µ I B t α I A Spin-space term Z 1 I spin space = 1 + δbc d 3 K B d 3 K C d 3 p αd 3 p β d 3 p µd 3 p νδ (3) ( K K 0) δ (3) ( K B P B )δ (3) ( K C P C )δ (3) ( p µ + p ν)δ (3) ( P δ(k k0) A ) k {[[φ B ( p B )(s αs ν)s B ] J B [φ C ( p C )(s µs β )S C ] J C ] J BC Y l (ˆk)} J A «pµ p ν {[φ A ( p A )(s αs β )S A ] J A [γ µ,(1) (s µs ν)1] 0}J A 2

18 Comparative with other microscopic models: ψ(3770) DD decay Prediction from Phys. Rev. D (2006) Γ(ψ(3770) DD) = 20.1 MeV Prediction using the model of E.S. Ackleh et al. Γ(ψ(3770) DD) = 104.0MeV Prediction with a mixture of scalar-vector screened confinement Γ(ψ(3770) DD) = 19.0MeV

19 Comparative with other microscopic models (Continuation) Comparative of the j 0 Kj 0 term Decay Cornell Model Our model ψ(3770) DD We can calculate the matrix elements taking into account the different Lorentz structures We can generalize the dependence of the kernel with the interquark distance ψ(4040) DD ψ(4040) DD ψ(4040) D D ψ(4040) DsDs total ψ(4160) DD ψ(4160) DD ψ(4160) D D ψ(4160) DsDs ψ(4160) DsDs total State Ratio Cornell j 0 Kj 0 Our model 3 P 0 Measured ψ(4040) D D/D D ± 0.05 ± 0.12 D D /D D ± 0.14 ± 0.03 ψ(4160) D D/D D ± 0.03 ± 0.02 D D /D D ± 0.14 ± 0.05 X(4360) D D/D D ± 0.12 ± 0.03 D D /D D ± 0.25 ± 0.03 ψ(4415) D D/D D ± 0.12 ± 0.03 D D /D D ± 0.25 ± 0.03

20 Excited states J. Segovia, D. R. Entem and F. Fernández, Phys. Rev. D 78, (2008) Meson State channel Γ3 P 0 B3 P 0 Γ B ψ(3770) 1 3 D 1 D + D D 0 D ± 2.5 (PDG2006) DD ± 1.0 (PDG2010) total ψ(4040) 3 3 S 1 DD DD D D D sd s ± 10 total ψ(4160) 2 3 D 1 DD DD D D D sd s D sds ± 8 total

21 Excited states (Continuation) Meson State channel Γ3 P 0 B3 P 0 Γ B X(4360) 4 3 S 1 DD DD D D DD DD DD D sd s D sds Ds D s ± 15 ± 10 total ψ(4415) 3 3 D 1 DD DD D D DD DD DD D D D sd s D sds Ds D s ± 20 total

22 Excited states (Continuation) Meson State channel Γ3 P 0 B3 P 0 Γ B X(4630) 5 3 S 1 DD DD D D DD DD DD D D D D D D D D D sd s D sds Ds D s D sd s D sd s D sds Ds Ds Ds D s Ds D s Ds0 D s total

23 Excited states (Continuation) Meson State channel Γ3 P 0 B3 P 0 Γ B X(4660) 4 3 D 1 DD DD D D DD DD DD D D D D D D D D D sd s D sds Ds Ds D sd s D sd s D sds Ds D s Ds D s Ds D s Ds0 D s ± 15 ± 3 total

24 6.- Introduction We have studied the charmonium strong decays to open-charm mesons using a QCD based model Very poor understood area because it is a non-perturbative process Few previous works E. Eichten et al. Phys. Rev. D (1978); (1980) update: Phys. Rev. D (2006) E.S. Ackleh et al. Phys. Rev. D 54, 6811 (1996) Very recent works: Yu.A. Simonov arxiv: v1 [hep-ph] 21 Mar 2011 and Bao-Fei Li et al. arxiv: v1 [hep-ph] 9 May 2011 A pure scalar linear confining interaction, which is generally accepted, predicts large widths A static vector linear confining interaction predicts a reasonable widths Using a mixture of scalar-vector linear screened confining interaction we also obtain the correct order of magnitude It is difficult to draw conclusions due to the limited experimental data