Hadron Fragmentation New Results from Belle Matthias Grosse
Hadron Fragmentation New Results from Belle Matthias Grosse Perdekamp, Illinois • Motivation • Belle and KEK-B • Unpolarized Hadron Fragmentation for Charged Pions and Kaons • Global Analysis and Comparison with Ba. Bar • Future Measurements of p. T Dependence Transversity 2014 Chia, Domus de Maria, Italy June 9 th– 13 th 2014 + - Unpolarized Hadron Fragmentation in e e at Belle
RIKEN BNL Transversity Workshop 2000 Motivation: Combined Effort to Measure Transversity Distributions HERMES COMPASS JLab SIDIS ~ δq(x) x CFF(z) ~ δq(x) x IFF(z) Measure CFF and IFF asymmetries in Belle ! D. Boer, A. Ogawa, MGP Belle e+e- Ba. Bar ~ CFF(z 1) x CFF(z 2) ~ IFF(z 1) x IFF(z 2) ~ D(z) Theory First ideas and attempts at LEP: A. Efremov, et al. (NPPSuppl. 74, 1999) ! Transversity, δq(x) Tensor Charge RHIC pp jets ~ G(x 1)xδq(x 2) x CFF(z) + - pp h + X ~ G(x 1)xδq(x 2) x IFF(z) 1 Lattice QCD: Tensor Charge = Σq=u, d∫ 0 δq(x)dx June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 2
Available Results on Spin-Dependent and Spin-Independent Fragmentation from Belle Collins FF for charged pions (R. Seidl, Illinois + K. Hasuko RIKEN) Off-Resonance: Phys. Rev. Lett. 96: 232002, 2006 On-Resonance: Phys. Rev. D 78: 032011, 2008 Transversity 2005 Transversity 2008 (Theoretical aspects: Daniel Boer, Nucl. Phys. B 806: 23 -67, 2009) Interference FF for pion pairs (A. Vossen Illinois/Indiana + R. Seidl, RIKEN) On-Resonance: Phys. Rev. Lett. 107: 072004, 2011 Transversity 2011 Unpolarized FFs for charged pions and Kaons (M. Leitgab, Illinois) Collins FF for charged Kaons (F. Giordano, Illinois) Unpolarized FF : Phys. Rev. Lett. 111: 062002, 2013 Kaon Collins FF: released at DIS 2014 Transversity 2014 Also a first at this year’s Transversity workshop: STAR results on IFF (A. Vossen, Indiana) June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 3
Motivation for High Statistics Measurement for Hadron Multiplicities at B-Factories limited data for z>0. 7 and at low Q 2 Unpolarized Hadron Fragmentation in e+e- at Belle 4
KEK-B: High Luminosity, L = 2. 1 x 1034 cm-2 s-1 at low Backgrounds – Asymmetric collider: 8 Ge. V e- + 3. 5 Ge. V e+ Ös = 10. 58 Ge. V , e+e- ϒ(4 S) B B Ös = 10. 52 Ge. V e+e- q q (u, d, s, c) – Available statistics: 1. 8 x 109 events (on resonance) [Collins Analysis] 220 x 106 events (off-resonance) [Spin Averaged D(z)] (Delphi at LEP ~ 6 x 106 events) KEKB “off” “on” Belle detector Critical innovations: (1) Continuous injection (2) 22 mrad beam crossing with crab cavities June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 5
KEK-B Critical Innovations: (A) Continuous Injection (B) 22 mrad Beam Crossing with Crab Cavities (A) Constant Beam Current through Continuous Injection (B) Avoidance of parasitic beam crossings without loss of luminosity high energy ring - beam current low energy ring - beam current 22 mrad. crossing ∫Ldt vs day time ∫Ldt =1 fb-1/day crab crossing 24 hours June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 6
Belle Detector: Large acceptance, Good Tracking and Particle ID June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 7
Hadron Multiplicity Analysis in Belle June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 8
Belle Results on Hadron Multiplicities for Charged Pions and Kaons Similar for Kaons June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 9
Comparison with Previous Data Sets Pions Kaons June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 10
Update to DSS Fit Including Belle and Ba. Bar Data from R. Sassot [Fragmentation Function Workshop in December 2013 in Bloomington] Overall normalization factors needed to obtain consistent fit with previous e+e- data sets NBelle=1. 058, NBar. Bar=1. 021. At large z, Belle Multiplicities drop off faster than Bar’s June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 11
Updated Pion Fragmentation Functions from R. Sassot [Fragmentation Function Workshop in December 2013 in Bloomington] Main new feature: gluon FF changes with inclusion of ALICE data Belle and Ba. Bar data consistent with other data sets. Impact limited by uncertainty in the normalization June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 12
Projections for Super Belle KEKB Upgrade & Luminosity Backgrounds & Detectors Projections for di-hadron yields and p. T dependent yields Unpolarized Hadron Fragmentation in e+e- at Belle 13
Upgrade Plan for Super KEKB • Initial target: 10×higher luminosity ~ 2 1035/cm 2/sec • Final goal: L=8 1035/cm 2/sec and ∫L dt = 50 ab-1 Crab cavity 8 Ge. V e- New IR with crab crossing and smaller by* 3. 5 Ge. V e+ New beam-pipe with ante-chamber More RF for higher beam current Damping ring for e+ beam SR Unpolarized Hadron Fragmentation in e+e- at Belle Assume 5 ab- 1 off-resonance for FF analysis !
New Detector Required for 20 Times Increased Background (Super -) Unpolarized Hadron Fragmentation in e+e- at Belle
Super Belle Faster calorimeter with waveform sampling and pure Cs. I (endcap) New particle identifier with precise Cherenkov device: (i)TOP or f. DIRC. KL/m detection with scintillator and next generation photon sensors New dead time free pipelined readout and high speed computing systems Background tolerant super small cell tracking detector Si vertex detector with high background tolerance & fast readout Unpolarized Hadron Fragmentation in e+e- at Belle
Observe p. T Dependence of Yields for e+e- Annihilation into Hadron Pairs electron Constrain p. T-dependence of fragmentation functions h 2, z 2 p. T Combinations: z relative hadron momenta positron Unpolarized Hadron Fragmentation in e+e- at Belle 17
1 0. 2 < z< 0. 25 Relative Stat. Error 1 10 -2 10 -3 10 -4 10 -5 0. 5 < z < 0. 55 10 -1 10 -2 10 -3 10 -4 10 -5 p. T[Ge. V] 10 -1 10 -2 10 -3 10 -4 10 -5 0. 7 < z < 0. 75 1 Relative Stat. Error 1 p. T[Ge. V] 0. 9 < z < 0. 95 10 -1 10 -2 10 -3 10 -4 10 -5 from Martin Leitgab Unpolarized Hadron Fragmentation in e+e- at Belle p. T[Ge. V] 18
Summary • High statistics hadron multiplicties for charged pions and kaons available from Belle and Ba. Bar. • Data sets are consistent with existing data from e+e-, pp and SIDIS after changing the normalization by 5. 8% for Belle and 2. 1% for Ba. Bar. • The difference in normalization is presently not understood and requires further study. • Precise measurements of the p. T dependence of FF are possible both with Belle I and Belle II data sets in the future. June 12 th Unpolarized Hadron Fragmentation in e+e- at Belle 19
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