Nuclear PDFs: latest update (and future facilities) P. Zurita February 16th, 2017 Wright laboratory, Yale University, CT, USA
Disclaimer I will talk only about observables included in PDFs and npdfs fits, computed with dear old pqcd. Any other measurement can eventually be included, just not part of the talk :)
Outline The questions: what, why, how? Where were we? Where are we? Where are we going? Summary
WHAT? What are PDFs? d (p + l! l 0 + X) = X a dˆla!l 0 X f a d (p + l! l 0 + X + h) = X a,b dˆla!b f a D h b d (p + p! l++l ) = X a,b dˆab!l l f a f b d (p + p! X + h) = X a,b,c dˆab!c f a f b D h c
WHAT? What are PDFs? d (p + l! l 0 + X) = X a dˆla!l 0 X f a d (p + l! l 0 + X + h) = X a,b dˆla!b f a D h b d (p + p! l++l ) = X a,b dˆab!l l f a f b d (p + p! X + h) = X a,b,c dˆab!c f a f b D h c hard
WHAT? What are PDFs? d (p + l! l 0 + X) = X a dˆla!l 0 X f a d (p + l! l 0 + X + h) = X a,b dˆla!b f a D h b d (p + p! l++l ) = X a,b dˆab!l l f a f b d (p + p! X + h) = X a,b,c dˆab!c f a f b D h c SOFT
WHAT? But the title reads nuclear PDFs
WHAT? But the title reads nuclear PDFs early 80 s: measurement of DIS crosssections in e-a collisions d 2 eh!ex dxdq 2 = 4 2 e.m. xq 4 " 1 y + y2 2! F 2 (x, Q 2 ) y 2 2 F L(x, Q 2 ) #
WHAT?
WHAT? effect in cross-section is this a hard, soft or hard and soft effect?
WHAT? pqcd is successful don t want to throw it away the proposal is: factorization holds change only in the soft part
WHAT? so now d (A + l! l 0 + X) = X a dˆla!l 0 X f A a d (A + l! l 0 + X + h) = X a,b dˆla!b f A a D h b d (A + p! l++l ) = X a,b dˆab!l l f A a f b d (A + p! X + h) = X a,b,c dˆab!c f A a f b D h c
WHY? do I need these? really? WHY?
WHY? do I need these? really? WHY? because in QCD they are crucial for describing the perturbative regime of
WHY? do I need these? really? WHY? because in QCD they are crucial for describing the perturbative regime of nuclear DIS
WHY? do I need these? really? WHY? because in QCD they are crucial for describing the perturbative regime of nuclear DIS non QGP effects in p-a, d-a, A-A
WHY? do I need these? really? WHY? because in QCD they are crucial for describing the perturbative regime of nuclear DIS non QGP effects in p-a, d-a, A-A cosmic rays
WHY? do I need these? really? WHY? because in QCD they are crucial for describing the perturbative regime of nuclear DIS non QGP effects in p-a, d-a, A-A cosmic rays neutrino DIS (needed for proton PDFs)
HOW? How? All soft contributions are determined by global QCD analyses
HOW? How? All soft contributions are determined by global QCD analyses pick data sets
HOW? How? All soft contributions are determined by global QCD analyses pick data sets compute the observables
HOW? assumed initial shape of the nuclear/proton PDF ratio (R valence, R sea and R gluon ) 1.5 y a antishadowing Fermimotion 1.0 0.6 y 0 shadowing EMCeffect y e 0.2 x a x e 10-3 10-2 10-1 1 f p/a i (x, Q 0 )=f p i (x, Q 0)R i (x, A) A-dependent parameters
HOW? How? All soft contributions are determined by global QCD analyses pick data sets compute the observables construct 2 2 X 2= = i w i d exp i i d i th! 2 weights: amount and accuracy of the data data sets: DIS, DY, p(d)-a, SIDIS, cross-sections, rates theory: LO, NLO, quarks mass error treatment: correlation matrix
HOW? How? All soft contributions are determined by global QCD analyses pick data sets compute the observables construct 2 2 X 2= = i w i d exp i i d i th! 2 weights: amount and accuracy of the data data sets: DIS, DY, p(d)-a, SIDIS, cross-sections, rates theory: LO, NLO, quarks mass error treatment: correlation matrix move parameters until minimum reached
HOW? How? All soft contributions are determined by global QCD analyses pick data sets compute the observables construct 2 2 X 2= = i w i d exp i i d i th! 2 weights: amount and accuracy of the data data sets: DIS, DY, p(d)-a, SIDIS, cross-sections, rates theory: LO, NLO, quarks mass error treatment: correlation matrix move parameters until minimum reached all done!
HOW? too good to be true
HOW? too good to be true which data sets? to which order? heavy quarks mass effects? scales? error treatment? weights? parameters??
WHERE WERE WE? LO EKS: Eskola, Kolhinen, Salgado, Eur.Phys.J. C9 (1999) HKM: Hirai, Kumano, Miyama, Phys.Rev. D64 (2001) nds: de Florian, Sassot, Phys.Rev. D69 (2004) HKN: Hirai, Kumano, Nagai, Phys.Rev. C76 (2007) > KEK nuclear physics textbook (2015) NLO EPS09: Eskola, Paukkunen, Salgado, JHEP 0904 (2009) DSSZ: de Florian, Sassot, Stratmann, PZ, Phys.Rev. D85 (2012) ncteq15: Kovarik et al., Phys.Rev. D93 (2016) EPPS16: Eskola, Paakkinen, Paukkunen, Salgado, arxiv:1612.05741 NNLO KA15: Khanpour, Tehrani, Phys.Rev. D93 (2016) no.1, 014026 to come a) A-Z: NNLO b) NNPDF: Pb npdfs
WHERE WERE WE? Paukkunen, Nucl. Phys. A 926 (2014) 24
WHERE WERE WE? de Florian, Sassot, Stratmann, PZ, Phys.Rev. D85 (2012) d dau /d pp 1.8 1.6 1.4 1.2 1 0.8 0 0.6 0.4 PHENIX STAR 1.6 + most gluon sensitive data d dau /d pp 1.4 1.2 1 0.8 0.6 0.4 this fit (nff) this fit (DSS) (62 points) d dau /d pp 1.6 1.4 1.2 1 0.8 0.6 0.4 0 5 10 15 - EPS 09 (DSS) nds (DSS) p T [GeV]
WHERE WERE WE? Paukkunen, Nucl. Phys. A 926 (2014) 24 Outside the kinematical region probed by the experiments we have extrapolations given by the initial shape model dependent not entirely reliable
WHERE WERE WE? in general with the data we had - High x: no constraints - Low x: extrapolations - No sensitivity to flavour separation - No sensitivity to gluon density at low nor high x
d a t a t y p e SET DSSZ PRD85 (2012) ncteq15 PRD93 (2016) KA15 PRD93 (2016) e-dis D-Y pions ν-dis EW jets # data points 1579 740 1479 accuracy NLO NLO NNLO proton PDF MSTW2008 ~ CTEQ6.1 JR09 flavour separation? no valence only no
Where are we after LHC Run I?
WHERE ARE WE? form the ppb white paper estimations J.Phys. G39 (2012) 015010
WHERE ARE WE? Before EPPS16 N. Armesto, H. Paukkunen, J.M. Penín, C. A. Salgado and P.Z., EPJ C76 (2016) no.4, 218 jets (ATLAS) charged hadrons (ALICE, CMS) and pions (ALICE) W boson (ALICE, CMS) and Z boson (ATLAS, CMS) di-jets (CMS) only the last two included in EPPS16 arxiv:1612.05741 http://www.int.washington.edu/talks/workshops/int_17_65w/
WHERE ARE WE? arxiv:1612.05741
WHERE ARE WE? Z d (y Z )/d ( y Z ) No nuclear e ects ATLAS data EPPS16 Zproduction,pPb, p s =5.02 TeV 66 GeV <M`+` < 116 GeV d (y Z 0.4)/d ( y Z 0.4) CMS data No nuclear e ects EPPS16 Zproduction,pPb, p s =5.02 TeV p T (`±) > 20 GeV `± lab < 2.4 60 GeV <M`+` < 120 GeV y Z y Z 0.4 x M Z,W p s e y arxiv:1612.05741
WHERE ARE WE? W +/- Phys.Lett. B750 (2015) 565-586 good candidate for flavour decomposition
WHERE ARE WE? W +/- d (y`+)/d ( y`+) CMS data No nuclear e ects EPPS16 W + production, ppb p s =5.02 TeV p T (`+) > 25 GeV d (y` )/d ( y` ) W CMS data No nuclear e ects EPPS16 production, ppb, p s =5.02 TeV p T (` ) > 25 GeV lepton rapidity (lab frame) lepton rapidity (lab frame) arxiv:1612.05741
WHERE ARE WE? W +/- Phys.Lett. B750 (2015) 565-586 good candidate for flavour decomposition arxiv:1612.05741
WHERE ARE WE? di-jets Eur.Phys.J. C74 (2014) no.7, 2951
WHERE ARE WE? di-jets arxiv:1612.05741
WHERE ARE WE? R valence arxiv:1612.05741
WHERE ARE WE? R sea arxiv:1612.05741
WHERE ARE WE? R gluon arxiv:1612.05741
d a t a t y p e SET DSSZ PRD85 (2012) ncteq15 PRD93 (2016) KA15 PRD93 (2016) EPPS16 arxiv:1612.05741 e-dis D-Y pions ν-dis EW jets # data points 1579 740 1479 1811 accuracy NLO NLO NNLO NLO proton PDF MSTW2008 ~ CTEQ6.1 JR09 CT14NLO flavour separation? no valence only no yes!
WHERE ARE WE? the new set is great, but what have we learned so far?
WHERE ARE WE? the new set is great, but what have we learned so far? - call for flavour separation in the npdfs can be answered by data - di-jets strongly depend on proton PDFs - accurate FFs needed
WHERE ARE WE GOING? The future: LHC Run II RHIC EIC LHeC??
WHERE ARE WE GOING? TO CERN LHC: - Run I: measured pp reference @5TeV, ratios to be re-analysed, observables not considered before could be included - Run II: already a pp reference @ 8TeV, LHCb involved, new FFs to come
WHERE ARE WE GOING? TO BNL Aschenauer et al., arxiv:1602.03922 [nucl-ex] direct photon g + q! q +
WHERE ARE WE GOING? TO BNL Aschenauer et al., arxiv:1602.03922 [nucl-ex] direct photon g + q! q + R g (Pb)(x,Q 2 =1.0 GeV 2 ) 1.5 DSSZ before rew. DSSZ after rew. 1 0.5 0 10-4 10-3 10-2 10-1 1 R g (Pb)(x,Q 2 =1.69 GeV 2 ) 1.5 EPS09 before rew. EPS09 after rew. 1 0.5 0 10-4 10-3 10-2 10-1 1 x x
WHERE ARE WE GOING? TO BNL Aschenauer et al., arxiv:1602.03922 [nucl-ex] Drell-Yan
WHERE ARE WE GOING? TO BNL Aschenauer et al., arxiv:1602.03922 [nucl-ex] Drell-Yan R sea (Pb)(x,Q 2 =1.0 GeV 2 ) 1.2 1 0.8 DSSZ before rew. DSSZ after rew. 0.6 0.4 0.2 10-4 10-3 10-2 10-1 1 x R sea (Pb)(x,Q 2 =1.69 GeV 2 ) 1.2 1 0.8 EPS09 before rew. EPS09 after rew. 0.6 0.4 0.2 10-4 10-3 10-2 10-1 1 x
WHERE ARE WE GOING? TO BNL? Accardi et al., Eur.Phys.J. A52 (2016) no.9, 268 Great possibilities!
WHERE ARE WE GOING? TO BNL? F 2 (x,q 2 ) - log 10 (x) 5 4.5 4 3.5 3 2.5 2 1.5 1 F 2 in e+au x = 2.0 10-4 3.2 10-4 5.2 10-4 8.2 10-4 1.3 10-3 2.0 10-3 3.2 10-3 5.2 10-3 8.2 10-3 5 on 50 GeV 5 on 100 GeV 20 on 100 GeV F 2 World Data (A Fe) CTEQ10+EPS09 1.3 10-2 2.0 10-2 Ldt = 10 fb -1 /A Errors enlarged by factor 3 3.2 10-2 5.2 10-2 8.2 10-2 1.3 10-1 2.0 10-1 F L (x,q 2 ) - log 10 (x) 5 4.5 4 3.5 3 2.5 2 1.5 1 F L in e+au x = 3.7 10-4 x = 6.3 10-4 x = 1.4 10-3 x = 2.6 10-3 x = 3.8 10-3 x = 5.8 10-3 x = 9.1 10-3 x = 1.6 10-2 x = 3.0 10-2 Ldt = 10 fb -1 /A 20 on 50,75,100 GeV 5 on 50,75,100 GeV 0.5 0 1 10 10 2 10 3 Q 2 (GeV 2 ) 3.2 10-1 5.2 10-1 8.2 10-1 0.5 0 1 10 10 2 10 3 Q 2 (GeV 2 ) Accardi et al., Eur.Phys.J. A52 (2016) no.9, 268
WHERE ARE WE GOING? TO BNL? F 2 c c (x,q 2 ) - log10 (x)/10 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 x = 2.0 10-4 3.2 10-4 5.2 10-4 8.2 10-4 1.3 10-3 2.0 10-3 3.2 10-3 5.2 10-3 8.2 10-3 1.3 10-2 2.0 10-2 F 2 c c in e+au 5 on 50 GeV 5 on 100 GeV 20 on 100 GeV CTEQ10+ EPS09 3.2 10-2 5.2 10-2 8.2 10-2 Never measured for ea! 0.1 0.05 Ldt = 10 fb -1 /A 0 1 10 10 2 10 3 Q 2 (GeV 2 ) 1.3 10-1 2.0 10-1 3.2 10-1 5.2 10-1 Accardi et al., Eur.Phys.J. A52 (2016) no.9, 268
WHERE ARE WE GOING? TO BNL? J.H. Lee, IS2016, Lisbon
WHERE ARE WE GOING? TO BNL? R A = N (x,q 2,z) N e (x,q 2 ) N (x,q 2,z) N e (x,q 2 ) A d Sassot, Stratmann and P.Z., Phys.Rev. D81 (2010) 054001
WHERE ARE WE GOING? TO CERN? Aballeira et al., J. Phys. G 39 (2012) 075001
WHERE ARE WE GOING? TO CERN? Armesto, Helenius and Paukkunen, PoS DIS2016 (2016) 276
WHERE ARE WE GOING? TO CERN? Armesto, Helenius and Paukkunen, PoS DIS2016 (2016) 276
Summary several sets of npdfs available
Summary several sets of npdfs available strange and gluon distributions not yet well constrained by data
Summary several sets of npdfs available strange and gluon distributions not yet well constrained by data p-pb @ the LHC and pa @ RHIC crucial to study the low x region
Summary several sets of npdfs available strange and gluon distributions not yet well constrained by data p-pb @ the LHC and pa @ RHIC crucial to study the low x region EIC (LHeC?) to go further
ongoing and to do nuclear effects truly universal? correlated errors? more data in DY? high pt particle production? cross-sections instead of structure functions? nuclear effects for deuteron? more flexible parameterizations? higher fixed-order analyses? A-A collisions? centrality dependence? final state nuclear effects?...???
That s all folks!
That s all folks! for now