Transverse Momentum Dependence of SemiInclusive Pion and Kaon

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Transverse Momentum Dependence of Semi-Inclusive Pion and Kaon Production E 12 -09 -017 Spokespersons

Transverse Momentum Dependence of Semi-Inclusive Pion and Kaon Production E 12 -09 -017 Spokespersons P. Bosted, R. Ent, , E. Kinney and H. Mkrtchyan • Not much is known about the orbital motion of partons • Significant net orbital angular momentum of valence quarks implies significant transverse momentum of quarks Main goal: Map the p. T dependence (p. T ~ L < 0. 5 Ge. V) of p+ and p- production off proton and deuteron targets to study the k. T dependence of (unpolarized) up and down quarks Beam Time Request: Total: 6. 5 days at 8. 8 Ge. V 25. 5 days at 11. 0 Ge. V 32 days About 2/3 of running time scheduled for 2017 in Hall C

Transverse Momentum Dependence of Semi-Inclusive Pion and Kaon Production Outline: • SIDIS: general remarks

Transverse Momentum Dependence of Semi-Inclusive Pion and Kaon Production Outline: • SIDIS: general remarks and framework • Transverse momentum dependence of charged pions - Results from E 00 -108 & simple model analysis • E 12 -09 -017 Kinematics and Projected Results • Spin-off relevant for the general SIDIS program - Radiative correction modeling: linking to z = 1 - Single-spin asymmetries - Low-energy (x, z) factorization for charged kaons • The upcoming run preparations

Semi-Inclusive Deep-Inelastic Scattering Use advantages of multi-hall approach! Hall B: Large acceptance (CLAS 12),

Semi-Inclusive Deep-Inelastic Scattering Use advantages of multi-hall approach! Hall B: Large acceptance (CLAS 12), polarized H and D targets azimuthal distributions of final-state particles cross sections, single & double-spin asymmetries start kaon SIDIS program with RICH detector Hall A: Large acceptance in forward region with SOLID, Polarized 3 He target longitudinal & transversely polarized 3 He pion & kaon run with Big. Bite and SBS Access to n structure at high-x and high-Q 2 Hall C: Precision magnetic-spectrometer setup, p and K, high luminosity L/T separations in SIDIS precision cross sections and ratios of p+ and p- (and K+, K-)

SIDIS – k. T Dependence Final transverse momentum of the detected pion Pt arises

SIDIS – k. T Dependence Final transverse momentum of the detected pion Pt arises from convolution of the struck quark transverse momentum kt with the transverse momentum generated during the fragmentation pt. P t = p t + z kt + O(kt 2/Q 2) Linked to framework of Transverse Momentum Dependent Parton Distributions m p TMD x TMDu(x, k. T) f 1, g 1, f 1 T , g 1 T h 1, h 1 T , h 1 L , h 1

Transverse momentum dependence of SIDIS Linked to framework of Transverse Momentum Dependent Parton Distributions

Transverse momentum dependence of SIDIS Linked to framework of Transverse Momentum Dependent Parton Distributions m p TMD N U X q U f 1 L TMDq(x, k. T) T L f 1 T T h 1 Unpolarized target g 1 h 1 L Longitudinally pol. target g 1 T h 1 T Transversely pol. target Unpolarized k. T-dependent SIDIS: in framework of Anselmino et al. described in terms of convolution of quark distributions q and (one or more) fragmentation functions D, each with own characteristic (Gaussian) width Emerging new area of study I. Integrated over p. T and II. PT and f dependence f Hall C: PRL 98: 022001 (2007) Hall B: PRD 80: 032004 (2009) Hall C: PL B 665 (2008) 20 Hall C: PR C 85 (2012) 015202

SIDIS Formalism General formalism for (e, e’h) coincidence reaction w. polarized beam: [A. Bacchetta

SIDIS Formalism General formalism for (e, e’h) coincidence reaction w. polarized beam: [A. Bacchetta et al. , JHEP 0702 (2007) 093] (Y = azimuthal angle of e’ around the electron beam axis w. r. t. an arbitrary fixed direction) Use of polarized beams will provide useful azimuthal beam asymmetry measurements (FLU) at low p. T complementing CLAS 12 data

Transverse momentum dependence of SIDIS General formalism for (e, e’h) coincidence reaction w. polarized

Transverse momentum dependence of SIDIS General formalism for (e, e’h) coincidence reaction w. polarized beam: [A. Bacchetta et al. , JHEP 0702 (2007) 093] (Y = azimuthal angle of e’ around the electron beam axis w. r. t. an arbitrary fixed direction) Azimuthal fh dependence crucial to separate out kinematic effects (Cahn effect) from twist-2 correlations and higher twist effects. data fit on EMC (1987) and Fermilab (1993) data assuming Cahn effect → <m 02> = 0. 25 Ge. V 2 (assuming m 0, u = m 0, d)

Transverse momentum dependence of SIDIS E 00 -108 Pt dependence very similar for proton

Transverse momentum dependence of SIDIS E 00 -108 Pt dependence very similar for proton and deuterium targets, but deuterium slopes systematically smaller? targets

Unpolarized SIDIS – JLab E 00 -108 data Constrain k. T dependence of up

Unpolarized SIDIS – JLab E 00 -108 data Constrain k. T dependence of up and down quarks separately 1) Probe p+ and p- final states 2) Use both proton and neutron (d) targets 3) Combination allows, in principle, separation of quark width from fragmentation widths le mp a Ex Numbers are close to expectations! But, simple model only with many assumptions (factorization valid, fragmentation functions do not depend on quark flavor, transverse momentum widths of quark and fragmentation functions are gaussian and can be added in quadrature, sea quarks are negligible, assume Cahn effect, etc. ), incomplete cos(f) coverage, uncertainties in exclusive event & diffractive r contributions. <pt 2> (favored) 1 st example: Hall C, PL B 665 (2008) 20 le mp a Ex <kt 2> (up) x = 0. 32 z = 0. 55

Transverse Momentum Dependence: E 00 -108 Summary E 00 -108 results were only suggestive

Transverse Momentum Dependence: E 00 -108 Summary E 00 -108 results were only suggestive at best: • limited kinematic coverage - assumed (PT, f) dependency ~ Cahn effect • very simple model assumptions but PT dependence off D seems shallower than H Many limitations could be removed with 12 Ge. V: • wider range in Q 2, higher W, Mx • improved/full coverage in f (at low p. T) • larger range in PT • wider range in x and z (to separate quark from fragmentation widths) • possibility to check various model assumptions - Power of (1 -z) for D-/D+, quantitative contribution of Cahn term - Dup+ = Ddp-, Higher-twist contributions - consistency of various kinematics (global fit vs. single-point fits)

Choice of E 12 -09 -017 Kinematics • W 2 = 5. 08 Ge.

Choice of E 12 -09 -017 Kinematics • W 2 = 5. 08 Ge. V 2 and larger (up to 11. 38 Ge. V 2) • Use SHMS angle down to 5. 5 degrees (for p detection) HMS angle down to 10. 5 degrees (e- detection) separation HMS-SHMS > 17. 5 degrees • MX 2 = Mp 2 + Q 2(1/x – 1)(1 – z) > 2. 9 Ge. V 2 (up to 7. 8 Ge. V 2) • Choice to keep Q 2/x fixed qg ~ constant • exception are data scanning Q 2 at fixed x • All kinematics both for p+ (and K+) and p- (and K-), both for LH 2 and LD 2 (and Al dummy) • Choose z > 0. 3 (pp > 1. 7 Ge. V) to be able to neglect differences in s(p+N) and s(p-N)

Choice of Kinematics HMS + SHMS Accessible Phase Space for Deep Exclusive Scattering All

Choice of Kinematics HMS + SHMS Accessible Phase Space for Deep Exclusive Scattering All together: data base of precise SIDIS cross sections over nice range of x and Q 2! E 00 -108 11 Ge. V phase space 6 Ge. V phase space E 12 -06 -104 Scan in (z, p. T) No scan in Q 2 at fixed x: RDIS(Q 2) known E 12 -09 -017 Scan in (x, z, p. T) + scan in Q 2 at fixed x C 12 -09 -002 + scans in z For semi-inclusive, less Q 2 phase space at fixed x due to: i) MX 2 > 2. 5 Ge. V 2; and ii) need to measure at both sides of Qg

Choice of Kinematics – cont. Kin x Q 2 (Ge. V 2) Z Pp

Choice of Kinematics – cont. Kin x Q 2 (Ge. V 2) Z Pp (Ge. V) Qp (deg) I 0. 2 2. 0 0. 3 -0. 6 1. 7 – 3. 3 8. 0 – 23. 0 II 0. 3 3. 0 0. 3 -0. 6 1. 7 – 3. 4 5. 5 – 25. 5 III 0. 4 4. 0 0. 3 -0. 6 1. 7 – 3. 4 5. 5 – 25. 5 IV 0. 5 5. 0 0. 3 -0. 6 1. 7 – 3. 5 8. 0 – 28. 0 V 0. 3 1. 8 0. 3 -0. 6 1. 1 – 2. 1 8. 0 – 30. 5 VI 0. 3 4. 5 0. 3 -0. 6 2. 5 – 5. 0 5. 5 – 20. 5 Map of p. T dependence in x and z, in Q 2 to check (p. T/Q) and (p. T 2/Q 2) behavior Kinematics I, III, and IV are identical to those where this collaboration also plans to map R (= s. L/s. T) in SIDIS in E 12 -06 -104. These are the priority for 2017 run.

E 12 -09 -017: PT coverage Can do meaningful measurements at low p. T

E 12 -09 -017: PT coverage Can do meaningful measurements at low p. T (down to 0. 05 Ge. V) due to excellent momentum and angle resolutions! • Excellent f coverage up to p. T = 0. 2 Ge. V • Sufficient f coverage up to p. T = 0. 4 Ge. V f = 90 o p. T = 0. 6 p. T = 0. 4 (compared to the E 00 -108 case below, now also good coverage at f ~ 0 o) f = 180 o f = 0 o • Limited f coverage up to p. T = 1 Ge. V E 00108 f = 270 o PT ~ 0. 5 Ge. V: use f dependencies measured in CLAS 12 experiments (Run group A in particular)

C 12 -09 -017 Projected Results - I III IV II VI I V

C 12 -09 -017 Projected Results - I III IV II VI I V

Kaon Identification Particle identification in SHMS: 0) TOF at low momentum (~1. 5 Ge.

Kaon Identification Particle identification in SHMS: 0) TOF at low momentum (~1. 5 Ge. V) 1) Heavy (C 4 F 8 O) Gas Cherenkov to select p+ (> 3 Ge. V) 2) 60 cm of empty space can be used for two aerogel detectors, e. g. : - n = 1. 015 to select p+ (> 1 Ge. V) select K+ (> 3 Ge. V) - n = 1. 055 to select K+ (>1. 5 Ge. V) NSF-MRI grant to • Catholic U (lead) • U South Carolina • Mississippi State • Florida Intern. U (+ Yerevan + JLab)

Spin-off: study x-z Factorization for kaons P. J. Mulders, hep-ph/0010199 (EPIC Workshop, MIT, 2000)

Spin-off: study x-z Factorization for kaons P. J. Mulders, hep-ph/0010199 (EPIC Workshop, MIT, 2000) At large z-values easier to separate current and target fragmentation region for fast hadrons factorization (Berger Criterion) “works” at lower energies If same arguments as validated for p apply to K: At W = 2. 5 Ge. V: z > 0. 6 (but, z < 0. 65 limit may not apply for kaons!)

E 12 -09 -017 Projected Results - Kaons III IV II VI I V

E 12 -09 -017 Projected Results - Kaons III IV II VI I V

Systematic Uncertainties – the z 1 Limit From: G. Huber’s presentation on PR 12

Systematic Uncertainties – the z 1 Limit From: G. Huber’s presentation on PR 12 -06 -101 “Measurement of the Charged Pion Form Factor to High Q 2” Projected Systematic Uncertainty Source Spectrometer Acceptance Pt-Pt ε-random t-random εuncorrelated common to all t-bins Scale ε-global t-global 0. 4% 1. 0% 0. 2% 0. 8% - 0. 2% 0. 5% 0. 1% 0. 4% 1. 5% Target Thickness Beam Charge HMS+SHMS Tracking Coincidence Blocking 0. 2% PID 0. 4% Pion Decay Correction 0. 03% - 0. 5% - 0. 1% 1. 5% MC Model Dependence 0. 2% 1. 0% 0. 5% Radiative Corrections 0. 1% 0. 4% 2. 0% Kinematic Offsets 0. 4% 1. 0% - Pion Absorption Correction Added in quadrature: 1. 8%

The beam helicity asymmetry • Proportional to sin(f), must go to zero at Pt=0

The beam helicity asymmetry • Proportional to sin(f), must go to zero at Pt=0 • Interference term (L-T prime) • Very sensitive to details of interactions • Example: dramatic influence of Roper resonance in exclusive p+ electroproduction • Typical asymmetry 0. 05: need lots of statistics

Run Preparations Re-optimize run plan taking into account: 2 x higher accidental rates than

Run Preparations Re-optimize run plan taking into account: 2 x higher accidental rates than in proposal Data at 4 -pass and maybe 3 -pass for radiative correction modeling. Also, Need some data at 0. 6<z<1 at 5 -pass. Difficulties in going to small SHMS angles 5 pass energy of 10. 6 Ge. V

Run Preparations Adding option of measurements w/Carbon Plan to add to “dummy” target and

Run Preparations Adding option of measurements w/Carbon Plan to add to “dummy” target and Use z-resolution of HMS to distinguish Needed for CLAS 12 analysis with polarized ammonia Physics: Propogation of quarks through nu

Run Preparations Personael and Collaboration Great opportunity for Ph. D thesis! Great opportunity for

Run Preparations Personael and Collaboration Great opportunity for Ph. D thesis! Great opportunity for post-docs! And for young faculty members too.