Transversity in inclusive DIS

Transcription

1 Transversity in inclusive DIS Alberto Accardi Hampton U. and Jefferson Lab Transversity 2017 Laboratori Nazionali di Frascati, Dec 12th, 2017 Based on: Accardi, Baccheta, PLB 773 (2017) 632 Accardi, Signori, work in progres

2 Overview Inclusive DIS with jet correlators Quarks are not asymptotc states Cross secton & g2 revisited Twist-3 TMD sum rules New results, old ones revisited Measuring the jet correlator Concluding thoughts 2

3 Inclusive DIS with jet correlators Accardi, Baccheta, PLB 773 (2017) 632

4 TMDs in spin ½ targets PARTON PARTON SPIN SPIN TARGET TARGET SPIN SPIN QUARKS U g+ f1t^ g + g ag 5 h1^ f1 L T g +g 5 g1 ^ h1l g1t h1 h1t^ P. Mulders, QCDev2017 Integrated (collinear) correlator: only circled ones survive Christ-Lee theorem (1970): h 1 not observable in inclusive DIS Not quite true: Vacuum fuctuatons can fip the spin of the struck quark Large contributon ~h1 pops up in the g 2 g 2WW structure functon 4

5 Inclusive DIS with jet correlators AA, Bacchetta, PLB 773 ( 17) 632! W NE Jet correlators: non-asymptotc quark states 5

6 Factorization At order 1/Q, neglect k compared to q The cross secton only depends on the integrated jet correlator Coefcients can be interpreted in terms of quark spectral functons: Spin-fip average jet mass can couple to transversity! Exactly Positvity constraints imply Much larger than mq! 6

7 Jet and TMD sum rules Utlize the following jet correlator sum rule: At TMD level, this implies: Novel TMD sum rules Old ones (see later for more...) 7

8 Finally, the DIS cross section Inclusive DIS Integratng the SIDIS structure functons: Transversity in inclusive DIS! 8

9 Finally, the DIS cross section Inclusive DIS /EPJA 2016 Structure functons: Transversity in inclusive DIS! 9

10 g2 structure function revisited AA, Bacchetta, PLB 773 ( 17) 632 Using EOM, Lorentz Invariance Relatons, can show that Color force distributon Transversity in inclusive DIS! Consequences: h1 accessible in inclusive DIS! Potentally large signal new background to extracton of qgq efects Measuring the tensor charge 10

11 g2 structure function revisited AA, Bacchetta, PLB 773 ( 17) 632 Using EOM, Lorentz Invariance Relatons, can show that proton neutron 11

12 Novel non-perturbative sum rules AA, Bacchetta, PLB 773 ( 17) 632 Taking moments of g2 with Burkardt-Cotngham unlikely to stll be zero! Is BC breaking fnite? Perturbatvely, yes ( h~x ) but... 12

13 Novel non-perturbative sum rules AA, Bacchetta, PLB 773 ( 17) 632 Taking moments of g2 with Burkardt-Cotngham unlikely to stll be zero! Is BC breaking fnite? Perturbatvely, yes ( h~x ) but... Small-x asymptotcs: Kovchegov, Pitonyak, Sievert PRD(2017)93 But h1 is also non-singlet, expect Is BC badly broken? 1/Nc correctons non negligible? Or? 13

14 Novel non-perturbative sum rules AA, Bacchetta, PLB 773 ( 17) 632 Taking moments of g2 with Burkardt-Cotngham unlikely to stll be zero! Is BC breaking fnite? Perturbatvely, yes ( h~x ) but... Small-x asymptotcs: Kovchegov, Pitonyak, Sievert PRD(2017)93 But h1 is also non-singlet, expect How does spin propagate to small x? Is BC badly broken? 1/Nc correctons non negligible? Or? 14

15 Novel non-perturbative sum rules AA, Bacchetta, PLB 773 ( 17) 632 Taking moments of g2 with Burkardt-Cotngham Efremov-Teryaev-Leader Tensor charge Novel way to measure the tensor charge! 15

16 Novel non-perturbative sum rules AA, Bacchetta, PLB 773 ( 17) 632 Taking moments of g2 with Burkardt-Cotngham Efremov-Teryaev-Leader Tensor charge Color polarizability Color force Burkardt pure twist-3 background 16

17 Higher twist and color polarizability N.Sato et al., PRD93 (2015) Latce calcs from Goeckele et al tme to revist? 17

18 Higher twist and color polarizability N.Sato et al., PRD93 (2015) Latce calcs from Goeckele et al tme to revist? Can one also calculate Mjet on the latce? 18

19 New TMD sum rules Accardi, Signori, in preparaton

20 Quark-quark TMD sum rules General jet correlator sum rule: AA, Bachetta 17 Meissner, Metz, Pitonyak 10 longitudinal transverse At TMD level, take suitable traces and fnd: Longitudinal Transverse Collins-Soper Schaefer-Teryaev Twist-2 Twist-3! NEW! NEW! NEW 20

21 Quark-gluon-quark TMD sum rules Combine q-q sume rules using Equaton of Moton relatons:! NEW Transversity in DIS! Diehl-Sapeta! NEW NEW: proven at correlator level 21

22 Measuring the jet correlator In collaboraton with A.Baccheta, M.Radici, A.Signori

23 Measuring the jet correlator Accardi, Bacchetta, Radici, in prep. Related to confnement, mass generaton [C.Roberts] Jet mass Mjet can be measured in polarized e+ + e : Needs LT asymmetry in semi-inclusive Lambda producton Similarly a LU asymmetry in unpolarized dihadron producton 23

24 Need polarized e+e- colliders! Are existng facilites enough? adapted from Paticle Data Book BEPC super KEKB ILC JLab/BNL E beam [GeV] (e--) 7 (e--) 250? s [GeV] ? maybe 80% e-60% e+ YES! polarization? Can we get a (polarized) e+ e- collider at JLab / BNL? At JLab12? JLEIC? erhic? What else is interestng to study? Factorizaton tests for FFs (low s, unpol), Ideas? 24

25 Final thoughts

26 Final thoughts Jet correlators open up new theory and phenomenology Transversity contributes to inclusive g2 Extended BC and ETL sum rules New handle on proton tensor charge Open queston: spin transport to small x! New twist-3 TMD sum rules How to measure jet correlators? Polarized e+e- collider Observables in p+p?? How to calculate jet correlators? In latce QCD? Any relaton to chiral condensate? What can we learn from OPE? 26

27 Towards universal fits di-had FF transversity PDF pol PDF Frag Fns 27

28 di-had FF JA M + Pa v ia? Towards universal fits transversity M A J PDF 18 pol PDF Frag Fns JAM 15, 16, 17 J.Ethier s talk 28

29 di-had FF JA M + Pa vi a? Masters of the Universe transversity M A J A 3He deuteron Accardi, PoS DIS2015 PDF 18 pol PDF Frag Fns JAM 15, 16, 17 J.Ethier s talk 29

30 di-had FF JA M + Pa v ia? Masters of the Universe transversity M A J A 3He deuteron Accardi, PoS DIS2015 PDF 18 pol PDF Frag Fns JAM 15, 16, 17 J.Ethier s talk 30

31 Thank you!