Transversity experiment update

Transversity experiment update Hall A collaboration meeting, Jan 20 2016 Xuefei Yan Duke University E06-010 Collaboration Hall A collaboration

The Incomplete Nucleon: Spin Puzzle 1 2 = 1 2 ΔΣ + L q + J g Ji s sum rule Jaffe-Manohar 1990 Chen et al. 2008 Wakamatsu 2009,2010 [X. Ji, 1997] PRL 113, 012001 (2014) DIS DΣ 0.30 RHIC + DIS Dg not small L q Orbital angular momentum of quarks and gluons is important Understanding of spin-orbit correlations (atomic hydrogen, topological insulator..) How to access OAM? 2

Nucleon Polarization Leading-Twist TMD PDFs Nucleon Spin Quark Spin Unpolarized (U) Quark polarization Longitudinally Polarized (L) Transversely Polarized (T) U f 1 = h 1 = Boer-Mulders L g 1 = Helicity h 1L = Long-Transversity T f 1T = Sivers g 1T = Trans-Helicity h 1 = h 1T = Transversity Pretzelosity 3

E06-010: experimental configuration HRS L 16 o g * BigBite 30 o First neutron data in SIDIS SSA&DSA Similar Q 2 as HERMES experiment Inclusive asymmetries Results on SIDIS unpolarized cross section (new) p Polarized 3 He Target e e Electron beam: E = 5.9 GeV High luminosity L ~ 10 36 cm -2 s -1 40 cm transversely polarized 3 He target Average beam current 12 ua (max: 15 ua as in proposal) BigBite at 30 o as electron arm: P e = 0.6 ~ 2.5 GeV/c HRSL at 16 o as hadron arm: P h = 2.35 GeV/c 4

Access Parton Distributions through Semi-Inclusive DIS (SIDIS) Boer-Mulders Unpolarized Transversity Sivers Polarized Target Pretzelosity Polarized Beam and Target S L, S T : Target Polarization; e : Beam Polarization 5

Published results from E06-010 SIDIS Single Spin Asymmetries (SSA) X. Qian et al, Phys. Rev. Lett. 107, 072003 (2011): sizable π + Collins asymmetry at x=0.34 & negative π + Sivers asymmetries of neutrons Y. Zhang et al. Phys. Rev. C 90, 055209 (2014): Pretzelosity asymmetries consistent with 0 (within experimental uncertainties) Y. X. Zhao et al. Phys. Rev. C 90, 055201 (2014): K ± Collins & Sivers asymmetries Inclusive Single Spin Asymmetries (SSA) K. Allada, et al. Phys. Rev. C 89, 042201 (2014): SSA for K & proton consistent with 0, SSA for π ± has opposite sign from 3 He & neutron 6

Published results from E06-010 Double Spin Asymmetries (DSA) J. Huang et al., Phys. Rev. Lett. 108, 052001 (2012): None-zero SIDIS π ± cos(φ A h φ s ) LT DSA of neutrons, in CQ model non-zero quark OAM Y. X. Zhao et al. Phys. Rev. C 92 015207 (2015): π ±, K ± & Proton Inclusive A LT 7

Latest publication: results on 3 He and neutron 3 He & neutron A LT opposite sign with π ± consistent in sign with prediction using Wandzura- Wilczek approximation Magnitude of the predictions larger than data Calculation using the Sivers function is not consistent with data π ± asymmetries opposite sign: similar to A LT in SIDIS Y. X. Zhao et al. Phys. Rev. C 92 015207 (2015) To fully understand inclusive hadron production in terms of parton distributions and correlations: new theoretical and experimental efforts needed (Future experiments at Jefferson Lab; and future electron-ion collider) 8

Unpolarized differential cross section of Semi-Inclusive DIS dσ dxdydφ S dzdφ h dp h 2 = α2 xyq 2 y 2 2(1 ε) {F UU,T + ε F UU,L cosφ + 2ε 1 ε cos φ h F h UU +ε cos 2φ h F UU cos 2φ h } Twist 3 Cahn effect: cos φ h dependence Twist-2 Boer-Mulders & twist-4 Cahn : cos(2 φ h ) dependence Cahn effect f 1 D 1 Non-zero Cahn effect solely require non-zero quark transverse momentum Related to quarks intrinsic transverse momentum distribution While with twist-3, could be as large as 20-30% Boer-Mulders effect h 1 H 1 Boer-Mulders TMD PDF: transversely polarized quarks in unpolarized nucleon Twist-4 Cahn effect could have similar size of contribution to cos(2φ h ) as Boer- Mulders [Phys. Rev. D. 81:114026 (2010) based on HERMES/COMPASS results] 9

Unpolarized differential cross section Combine data with different target and beam polarizations for unpolarized cross section analysis Detector models in simulation for description of experimental acceptance Simulation vs. data in HRS and BigBite detector individually: inclusive DIS and elastic e-p processes Updated efficiency and contamination study with higher precision than SSA & DSA analysis (Sys. Uncertainty control) Exclusive tail subtraction & SIDIS radiative correction (SIMC & HAPRAD) 10

P e /GeV Vertex z /m # of event HRS simulation vs. data # of event Simulation Inclusive DIS on H 2 target Simulation Inclusive DIS on H 2 target P e /GeV Vertex z /m Simulation Inclusive DIS on 3 He target Simulation Inclusive DIS on 3 He target 11

P e /GeV Vertex z /m # of event BigBite simulation vs. data # of event Simulation Simulation Elastic e-p at 1.23 GeV beam Elastic e-p at 2.4 GeV beam W/GeV W/GeV Simulation Inclusive DIS on 3 He target Simulation Inclusive DIS on 3 He target 12

with efficiency/contamination correction in SIDIS channel # of events PID cut 1 PID cut 2 PID cut 3 PID cut 1-3: lower π contamination & higher loss of e in BigBite Consistency: data under 3 different PID cuts, corrected by related contamination and efficiency, respectively e + 3 He e + π + X SIDIS channel: e + 3 He e + π + X e detected by BigBite π detected by HRS P e /GeV 13

with efficiency/contamination correction in SIDIS channel # of events PID cut 1 PID cut 2 PID cut 3 PID cut 1-3: lower π contamination & higher loss of e in BigBite Consistency: data under 3 different PID cuts, corrected by related contamination and efficiency, respectively e + 3 He e + π + + X SIDIS channel: e + 3 He e + π + + X e detected by BigBite π + detected by HRS P e /GeV 14

Systematic uncertainty, largest items: BigBite Acceptance description: 2-5% (most bins), up to 10% (edge bins) with kinematics dependence Efficiency & contamination: 2-50% for π + channel, 2-30% for π Relative systematic uncertainty e+ 3 He e + π + X e+ 3 He e + π + + X P e <0.9 GeV range has large sys uncertainty Trigger: shower threshold non-uniform drift during experiment; off-line cut & loss of efficiency description unprecise Photon-induced e contamination: up to 40% & contain large uncertainty If NOT cut away low P range, unreasonably large uncertainty will go to multiple bins in other variables x, z, Q 2, etc. P e /GeV 15

Detector resolution checks Sieve Y /m HRS: sieve with small holes suffice the check BigBite: large sieve slots not ideal for checking # of events BigBite data HRS data No smear plot Resolution smear: 1.1% σ p, 0.2 degree σ θ BigBite Only use 3 center small holes to check first Use Elastic Electron- Proton W width to confirm in all acceptance (1.23 & 2.4 GeV beam) Sieve X /m W/GeV 16

Exclusive tail & radiative correction Exclusive channel cross section model: in SIMC from JLab π form factor experiments H. P. Blok et al. PRC 78 045202 (2008): Q 2 (0.6,2.45) GeV 2, W=1.95 &2.22 GeV V. Tadevosyan et al. PRC 75 055205 (2007): Q 2 (0.6,1.6) GeV 2 T. Horn et al. PRL 97 192001 (2006) Q 2 (1.6,2.45) GeV 2, W=2.22 GeV Q 2 (1. 3, 3. 5) GeV 2 in E06-010 Determined exclusive tail proportion consistent with R. Asaturyan et al. Phys. Rev. C 85, 015202 (2012) in overlapping kinematics range (Hall C SIDIS results) Radiative correction based on HAPRAD (close to SIMC built-in RC): SIDIS model iterative tuning 17

SIDIS model tuning: parameterizations Bacchetta, et al. PRL 107 212001 : k 2 =A GeV 2, p 2 =Bz C 1 z D GeV 2 (TMD_PDF=PDF(x) exp( k 2 / k 2 )) Note: this form was from HERMES data & SIDIS model tuning, PRL 107 212001 & L. L. Pappalardo, Ph.D. thesis, Univ. Ferrara, 2008 [http://wwwhermes.desy.de/notes/pub/08-lib/pappalardo.08-009.thesis.pdf] Bacchetta here fit SIDIS asymmetries & nucleon magnetic moments together & using above Gaussian ansatz width of transverse-momentum distribution Barone et al. PRD 91 (2015) 074019: use k 2 =A; p 2 =B+C z 2 form to fit multiplicity data & Cahn, Boer-Mulders moments Anselmino et al. JHEP 04 (2014) 005: use k 2 =A; p 2 =B form to fit multiplicity data only 18

SIDIS model tuning: parameterizations Barone PRD 91 074019 (2015): Multiplicities are only sensitive to P T 2 = z 2 k 2 + p 2, azimuthal moments sensitive to z dependence of p 2 Anselmino 2014 fit result had issue for cosφ h (up to 50%) Could also try other forms of parameterization (with different physics interpretation, comment from Barone 2015) In our data, tuning p 2 =Bz C 1 z D GeV 2 & use fixed k 2 have been able to make good comparisons between data & simulation With different k 2, different B, C & D need to be used for good matching with data 19

Cross section comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF e+ 3 He e + π + + X e+ 3 He e + π + X x bj Stat uncertainty in error bars (smaller than marker) Sys uncertainty in bottom band 20 x bj

Cross section comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF e+ 3 He e + π + X Model with MMHT2014 LO PDF e+ 3 He e + π + + X z had Stat uncertainty in error bars (smaller than marker) Sys uncertainty in bottom band 21 z had

Cross section comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF e+ 3 He e + π + X e+ 3 He e + π + + X P e /GeV Stat uncertainty in error bars (smaller than marker) P e /GeV Sys uncertainty in bottom band 22

Cross section comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF e+ 3 He e + π + + X dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF e+ 3 He e + π + X Q 2 /GeV 2 Stat uncertainty in error bars (smaller than marker) Q 2 /GeV 2 Sys uncertainty in bottom band 23

Cross section comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF e+ 3 He e + π + X Model with MMHT2014 LO PDF e+ 3 He e + π + + X φ h /rad Stat uncertainty in error bars (smaller than marker) φ h /rad Sys uncertainty in bottom band 24

Cross section comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF Model NO cos2φ h & cos2φ h e+ 3 He e + π + X Model with MMHT2014 LO PDF Model NO cosφ h & cos2φ h e+ 3 He e + π + + X φ h /rad Stat uncertainty in error bars (smaller than marker) φ h /rad Sys uncertainty in bottom band 25

Cross section comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF Model NO cosφ h & cos2φ h dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF Model NO cos2φ h & cos2φ h e+ 3 He e + π + X e+ 3 He e + π + + X x bj Stat uncertainty in error bars (smaller than marker) Sys uncertainty in bottom band 26 x bj

Cross section comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) dσ nb ( de e dω e de h dω h Sr 2 GeV 2) Model with MMHT2014 LO PDF Model NO cos2φ h e+ 3 He e + π + X Model with MMHT2014 LO PDF Model NO cos2φ h e+ 3 He e + π + + X φ h /rad Stat uncertainty in error bars (smaller than marker) φ h /rad Sys uncertainty in bottom band 27

Future work Different collinear PDF sets need different SIDIS model parameters to match the data Parameters difference from using D. Dutta et al. s PDF set including 3 He nucleus effect physics? (model tuning done, physics TBD) Other PDF sets, etc. with 3 He nucleus effect Combine with world data to constrain theory physics 28

Backup slides 29

Plots: resolution check Select only center 3 sieve holes Select all foils: vz will be multiple values Select only center foil: vz will be 1 value Sieve hole center values from optics code/database (X. Qian) Symbols and units in plots: tg_th/tg_ph: out/in plane angle, in rad theta/phi: physical angles, in degree 30

Angular resolution plot: selection A, all foil Center 3 small sieve holes selected All foils used here 31

Angular resolution plot: selection B, all foil Center 3 small sieve holes selected All foils used here 32

Angular resolution plot: selection A, 1 foil Center 3 small sieve holes selected Center foil used here 33

Angular resolution plot: selection B, 1 foil Center 3 small sieve holes selected Center foil used here 34

Summary plots of using individual foils & all foils with center sieve holes: fine bin X axis: 1-7=# of foils, 8=combining all foils Y axis: resolution σ from fit Error bar size: # of events weighted RMS, with center value= σ(8) Small # of events from foil 7 35

Total shower: series of cuts comparison dσ nb ( de e dω e de h dω h Sr 2 GeV 2) dσ nb ( de e dω e de h dω h Sr 2 GeV 2) e+ 3 He e + π + X Cut: 900 MeV (central) Cut: 800 MeV Cut: 850 MeV Cut: 950 MeV Cut: 1000 MeV : central with systematic uncertainty as error bars e+ 3 He e + π + + X Cut: 900 MeV (central) Cut: 800 MeV Cut: 850 MeV Cut: 950 MeV Cut: 1000 MeV : central with systematic uncertainty as error bars P e /GeV P e /GeV 36

x bj stat & sys uncertainties: no P e cut Uncertainty Uncertainty e+ 3 He e + π + X Sys Stat e+ 3 He e + π + + X Sys Stat x bj x bj 37

x bj stat & sys uncertainties: P e > 0.8 GeV Uncertainty Uncertainty e+ 3 He e + π + X Sys Stat e+ 3 He e + π + + X Sys Stat x bj x bj 38

x bj stat & sys uncertainties: P e > 0.9 GeV Uncertainty Uncertainty e+ 3 He e + π + X Sys Stat e+ 3 He e + π + + X Sys Stat x bj x bj 39

Exclusive tail in P e & x bj Exclusive tail size Exclusive tail size e+ 3 He e + π + + X e+ 3 He e + π + X e+ 3 He e + π + + X e+ 3 He e + π + X P e /GeV x bj 40

Exclusive tail in Q 2 & z had Exclusive tail size Exclusive tail size e+ 3 He e + π + + X e+ 3 He e + π + X e+ 3 He e + π + + X e+ 3 He e + π + X Q 2 z had 41

Cross section ratio comparison σ π +/σ π Model xy & MMHT2014 LO PDF Model xy & 3 He PDF Stat uncertainty in error bars Sys uncertainty to be defined: some uncertainty in absolute xs should cancel Some re-binning will be useful x bj 42

Kinematics correlations x bj x bj P e /GeV Q 2 /GeV 2 45

Kinematics correlations x bj x bj z had P h /GeV 46

Kinematics correlations x bj φ h /rad 47