Impact of sidis data on ppdfs. Rodolfo Sassot Buenos Aires

Transcription

1 Impact of sidis data on ppdfs Rodolfo Sassot Buenos Aires INT 1-3 Workshop, October 21

2 Outline: General Framework for Helicity Parton Densities (ppdfs) Status 21: DSSV, BB, LSS, NNPDFs... W-program, Run9,... Werners s talk 1 st week Impact of new sidis data (COMPASS) in ppdfs (DSSV,LSS1): what is the actual impact: on ppdfs on uncertainties what could we learn from future data where/what should we check implications for s

3 DSSV SMC A h+ HERMES A h+ SMC A h- HERMES A h- SMC A h+ HERMES A h+ SMC A h- HERMES A h- HERMES A + HERMES A h+ 1 He COMPASS A h+ HERMES A - HERMES A h- 1 He COMPASS A h- HERMES A + HERMES A K+ HERMES A - HERMES A K flavor at small-? strange/kaons? DSSV DNS (DSS FFs)

4 DSS FFs pions kaons pion ffs are safe 1 1 1/N DIS dn + /dzdq 2 THIS FIT KRE z - bin z z - bin /N DIS dn K /dzdq 2.3 z.4 THIS FIT KRE kaon ffs? 1 1 1/N DIS dn - /dzdq 2 not fitted Q 2 [GeV] z - bin /N DIS dn K /dzdq 2 not fitted Q 2 Q[GeV] 2 [GeV].4 z z - bin-.2.6 z Hermes

5 DSSV SMC A h+ HERMES A h+ SMC A h- HERMES A h- SMC A h+ HERMES A h+ SMC A h- HERMES A h- HERMES A + HERMES A h+ 1 He COMPASS A h+ HERMES A - HERMES A h- 1 He COMPASS A h- HERMES A + HERMES A K+ HERMES A - HERMES A K flavor at small-? strange/kaons? DSSV DNS (DSS FFs)

6 Compass Sidis Data:.4.2 A 1,d + A 1,d K+ A 1,d A 1,d K- A 1,d COMPASS preliminary, all deuteron data HERMES PRD71(2).2 M.G. Alekseev et al., Phys.Lett.B68:21724, A 1,p + A 1,p 1 K+ A 1,p COMPASS HERMES DSSV fit A 1,p K- A 1,p M.G. Alekseev et al., Phys.Lett.B693:2273,

7 DSSV+Compass d p.7 SMC A h+ HERMES A h+ HERMES A + HERMES A + COMPASS A + COMPASS A SMC A h- HERMES A h- HERMES A - HERMES A - COMPASS A - COMPASS A SMC A h+ COMPASS A h+ HERMES A h+ HERMES A K+ COMPASS A K+ COMPASS A K+.7 SMC A h- COMPASS A h- HERMES A h- HERMES A K- COMPASS A K- COMPASS A K HERMES A h+ 1 1 He HERMES A h- 1 He HERMES A K + K 1..2 DNS (DSS FFs) DSSV DSSV+ compass

8 HERMES A h+ HERMES A + HERMES A + COMPASS A + DSSV DSSV+ DNS COMPASS A + HERMES A h- HERMES A - HERMES A - COMPASS A - COMPASS A - COMPASS A h+ HERMES A h+ HERMES A K+ COMPASS A K+ COMPASS A K+ COMPASS A h- HERMES A h- HERMES A K- COMPASS A K- COMPASS A K-

9 Numerology : DSSV DSSV+ +d data d&p data ~2 units ~4 units DSSV well within the error bars of DSSV+ χ 2 χ 2 =1 is too little =2% is too much numerology: 1. the branch of knowledge that deals with the occult significance of numbers.

10 ppdfs.4 u d within bands.2 less polarization? DSSV DSSV+ DSSV+ 2% s DSSV 2 =1 DSSV 2 =2% g shrink at small

11 LSS1 arxiv:11.74 DIS+SIDIS DSS FFs TMC+HT for DIS data remarkable agreement

12 light sea quarks DSSV8 ± 9 K ± 9 ± +K ± 9 NEW 2 i 1 all data sets SIDIS DIS RHIC F, D all SIDIS K ± 8 ± 8 h ± 8 1 sizable impact on uncertainties (a) (b) new data prefer less polarization u 1, [.1. ] u 1, [.1. ] no tension: pions & kaons pull together 2 i 1 all data sets SIDIS DIS RHIC F, D (c) all SIDIS K ± ± h ± (d) d 1, [.1. ] d 1, [.1. ]

13 strange quarks 2 i 1 dis/3f-d cannot size sat large DSSV 8 all data sets SIDIS DIS RHIC F, D 1, [.1. ] s (a) s 1, [.2. ] all data sets SIDIS DIS RHIC F, D sizable impact on uncertainty compromise between dis and sidis sdata all data SIDIS not f,d DIS constraints! RHIC F, D 1, [.2. ] ± 9 K ± 9 ± +K ± 9 all SIDIS K ± 8 ± 8 h ± ± 9 K ± 9 ± +K ± 9 SIDIS K ± 8 ± 8 h ± need more/better sidis data at small strange: 1. unusual or surprising in a way that is unsettling or hard to understand s 2. not previously visited, seen, or encountered; unfamiliar or alien 3. having a nonzero value for strangeness , [.1-.2 ] , [.1-.2 ] s

14 can? s s.8 A 1,p.6 + A 1,p K+ A 1,p A 1 s + s K + us K us 1 COMPASS HERMES DSSV fit A 1,p K- A 1,p no significant effect at large 1 all data K+ p K- p K+ d K- d 1 all data K+ p K- p K+ d K- d too large errors at small , [.2. ] s , [.1-.2 ] s

15 Summary: new sidis data is in agreement with DSSV sizeable impact in the fit: d net item: the uncertainty bands shrink no tensions with the kaon data no surprises at small towards an unpolarized sea? negatively charged pions? s still an open issue: kaon sidis (pol & unpol) at small

16 Space for a personal/biased perspective A case for SIDIS/FFs: SIDIS/FFs until now in the backstage: large uncertainties this should change! FFs as fundamental as PDFs: not so well known yet more hard to measure FFs linked to fundamental physics: flavor & kinematic features of hadronization not well understood yet FFs/SIDIS as tools: d u =? s s =? isospin breaking SIDIS at EIC vs. PDFs uncertainties? hidden by nuclear effects limitations of dy/ w fundamental: 1. forming a necessary base or core; 2. of central importance; 3. affecting or relating to the essential nature of something or the crucial point about an issue