Current status of npdfs and future facilities

Transcription

1 Current status of npdfs and future facilities Carlota Andrés Universidade de Santiago de Compostela QCD evolution 2017, Jefferson Lab 1 / 24

2 Outline Introduction Pre-LHC global analysis Post-LHC run I Where are we going? Conclusions 2 / 24

3 Outline Introduction Pre-LHC global analysis Post-LHC run I Where are we going? Conclusions 2 / 24

4 Outline Introduction Pre-LHC global analysis Post-LHC run I Where are we going? Conclusions 2 / 24

5 Outline Introduction Pre-LHC global analysis Post-LHC run I Where are we going? Conclusions 2 / 24

6 Outline Introduction Pre-LHC global analysis Post-LHC run I Where are we going? Conclusions 2 / 24

7 Collinear factorization Factorization DGLAP equations 3 / 24

8 Global Analysis Choose data Parametrize the PDFs at the initial scale DGLAP evolution Compute the cross sections Evaluate χ 2 Minimize χ 2 Best fit Hessian analysis for uncertainties. 4 / 24

9 Global Analysis Choose data Parametrize the PDFs at the initial scale DGLAP evolution Compute the cross sections Evaluate χ 2 Minimize χ 2 Best fit Hessian analysis for uncertainties. 4 / 24

10 Global Analysis Choose data Parametrize the PDFs at the initial scale DGLAP evolution Compute the cross sections Evaluate χ 2 Minimize χ 2 Best fit Hessian analysis for uncertainties. 4 / 24

11 Global Analysis Choose data Parametrize the PDFs at the initial scale DGLAP evolution Compute the cross sections Evaluate χ 2 Minimize χ 2 Best fit Hessian analysis for uncertainties. 4 / 24

12 Global Analysis Choose data Parametrize the PDFs at the initial scale DGLAP evolution Compute the cross sections Evaluate χ 2 Minimize χ 2 Best fit Hessian analysis for uncertainties. 4 / 24

13 Global Analysis Choose data Parametrize the PDFs at the initial scale DGLAP evolution Compute the cross sections Evaluate χ 2 Minimize χ 2 Best fit Hessian analysis for uncertainties. 4 / 24

14 What is parametrized? Free proton baseline Data are of the form npdfs always relative to proton-free PDFs. 5 / 24

15 Flavor decomposition Free proton baseline Usually flavor independence (FI) is assumed at Q 0 : DGLAP destroyes flavor independence Flavor separation should be considered ncteq15: No FI for valence quarks. EPPS16: No FI for sea and valence quarks. 6 / 24

16 Before LHC run I 7 / 24

17 Paukkunen, Nucl. Phys. A 926 (2014) 24 Valence R uv = R dv 8 / 24

18 Paukkunen, Nucl. Phys. A 926 (2014) 24 Sea Agreement in the data-constrained region 8 / 24

19 Paukkunen, Nucl. Phys. A 926 (2014) 24 Gluon No constraints from DIS and Drell-Yan ncteq15, EPS09 and DSSZ: some constraints from inclusive pion production 8 / 24

20 Where were we? Extrapolations not completely reliable: Depend on the initial parametrization (model-dependent) Low x: extrapolations High x: no constraints Gluon: no sensitivity at low and high x No flavor decomposition 9 / 24

21 Where were we? Extrapolations not completely reliable: Depend on the initial parametrization (model-dependent) Low x: extrapolations High x: no constraints Gluon: no sensitivity at low and high x No flavor decomposition 9 / 24

22 Where were we? Extrapolations not completely reliable: Depend on the initial parametrization (model-dependent) Low x: extrapolations High x: no constraints Gluon: no sensitivity at low and high x No flavor decomposition 9 / 24

23 Where were we? Extrapolations not completely reliable: Depend on the initial parametrization (model-dependent) Low x: extrapolations High x: no constraints Gluon: no sensitivity at low and high x No flavor decomposition 9 / 24

24 Where were we? Extrapolations not completely reliable: Depend on the initial parametrization (model-dependent) Low x: extrapolations High x: no constraints Gluon: no sensitivity at low and high x No flavor decomposition 9 / 24

25 Where were we? Extrapolations not completely reliable: Depend on the initial parametrization (model-dependent) Low x: extrapolations High x: no constraints Gluon: no sensitivity at low and high x No flavor decomposition 9 / 24

26 Where are we? LHC run I 9 / 24

27 LHC Run I: data Charged hadrons (ALICE, CMS) and pions (ALICE) Jets (ATLAS) Di-jets (CMS) Gluon constraints at high x! W ± (ALICE, CMS) and Z 0 (ATLAS, CMS) bosons Flavor separation? Only last two included in EPPS16 10 / 24

28 LHC Run I: data Charged hadrons (ALICE, CMS) and pions (ALICE) Jets (ATLAS) Di-jets (CMS) Gluon constraints at high x! W ± (ALICE, CMS) and Z 0 (ATLAS, CMS) bosons Flavor separation? Only last two included in EPPS16 10 / 24

29 LHC Run I: data Charged hadrons (ALICE, CMS) and pions (ALICE) Jets (ATLAS) Di-jets (CMS) Gluon constraints at high x! W ± (ALICE, CMS) and Z 0 (ATLAS, CMS) bosons Flavor separation? Only last two included in EPPS16 10 / 24

30 LHC Run I: data Charged hadrons (ALICE, CMS) and pions (ALICE) Jets (ATLAS) Di-jets (CMS) Gluon constraints at high x! W ± (ALICE, CMS) and Z 0 (ATLAS, CMS) bosons Flavor separation? Only last two included in EPPS16 10 / 24

31 LHC Run I: data Charged hadrons (ALICE, CMS) and pions (ALICE) Jets (ATLAS) Di-jets (CMS) Gluon constraints at high x! W ± (ALICE, CMS) and Z 0 (ATLAS, CMS) bosons Flavor separation? Only last two included in EPPS16 10 / 24

32 Kinematic region Much higher Q 2 and lower x. EPPS16, arxiv: The LHC opens an unexplored kinematic region! 11 / 24

33 Global analysis Thanks to Paukkunen QM / 24

34 Z 0 production in p-pb EPPS16, arxiv: x Mz s e yz Data deviates from unity for non-symmetric acceptance Shadowing for y z > 0 Suppression 13 / 24

35 W ± production in p-pb EPPS16, arxiv: x Mz s e y l Isospin effects Baseline suppression Shadowing for y l± > 0 Suppression 14 / 24

36 Di-jets production in p-pb EPPS16, arxiv: Di-jets to constrain large-x gluons! Antishadowing for η dijet > 0 and EMC for η dijet < 0 Enhancement Data deviates from unity for non-symmetric acceptance 15 / 24

37 Di-jets production in p-pb EPPS16, arxiv: Di-jets to constrain large-x gluons! ncteq15: large di-jet uncertainty band DSSZ: similar to no nuclear effects 15 / 24

38 R valence EPPS16, arxiv: R V u Pb/p v +d Pb/p v uv p +dv p ncteq15: partly flavor dependence 16 / 24

39 R sea EPPS16, arxiv: R S ū Pb/p + d Pb/p + s Pb/p ū p + d p + s p EPPS16: more freedom for sea quarks Larger uncertainties 17 / 24

40 R gluon EPPS16, arxiv: EPPS16 more parameters larger uncertainties. Except: large-x (di-jet data) DSSZ almost no suppression 18 / 24

41 Summary LHC run I: novel constraints! Larger uncertainties, but lower bias Flavor separation possible with ν-dis data R uv R dv Di-jets: gluons more constrained at large x Correlated systematics missing! Accurate FFs needed Symmetric acceptances in the c.m frame! 19 / 24

42 Summary LHC run I: novel constraints! Larger uncertainties, but lower bias Flavor separation possible with ν-dis data R uv R dv Di-jets: gluons more constrained at large x Correlated systematics missing! Accurate FFs needed Symmetric acceptances in the c.m frame! 19 / 24

43 Summary LHC run I: novel constraints! Larger uncertainties, but lower bias Flavor separation possible with ν-dis data R uv R dv Di-jets: gluons more constrained at large x Correlated systematics missing! Accurate FFs needed Symmetric acceptances in the c.m frame! 19 / 24

44 Summary LHC run I: novel constraints! Larger uncertainties, but lower bias Flavor separation possible with ν-dis data R uv R dv Di-jets: gluons more constrained at large x Correlated systematics missing! Accurate FFs needed Symmetric acceptances in the c.m frame! 19 / 24

45 Summary LHC run I: novel constraints! Larger uncertainties, but lower bias Flavor separation possible with ν-dis data R uv R dv Di-jets: gluons more constrained at large x Correlated systematics missing! Accurate FFs needed Symmetric acceptances in the c.m frame! 19 / 24

46 Summary LHC run I: novel constraints! Larger uncertainties, but lower bias Flavor separation possible with ν-dis data R uv R dv Di-jets: gluons more constrained at large x Correlated systematics missing! Accurate FFs needed Symmetric acceptances in the c.m frame! 19 / 24

47 Summary LHC run I: novel constraints! Larger uncertainties, but lower bias Flavor separation possible with ν-dis data R uv R dv Di-jets: gluons more constrained at large x Correlated systematics missing! Accurate FFs needed Symmetric acceptances in the c.m frame! 19 / 24

48 Where are we going? 19 / 24

49 LHC: run I and run II LHC run I: p-p reference at s = 5 GeV measured R ppb Other observables possible LHC run II: already a p-p reference at s = 8 GeV Drell-Yan at LHCb Correlated systematics needed It would be better: same phase space for p-p and p-pb 20 / 24

50 LHC: run I and run II LHC run I: p-p reference at s = 5 GeV measured R ppb Other observables possible LHC run II: already a p-p reference at s = 8 GeV Drell-Yan at LHCb Correlated systematics needed It would be better: same phase space for p-p and p-pb 20 / 24

51 LHC: run I and run II LHC run I: p-p reference at s = 5 GeV measured R ppb Other observables possible LHC run II: already a p-p reference at s = 8 GeV Drell-Yan at LHCb Correlated systematics needed It would be better: same phase space for p-p and p-pb 20 / 24

52 LHC: run I and run II LHC run I: p-p reference at s = 5 GeV measured R ppb Other observables possible LHC run II: already a p-p reference at s = 8 GeV Drell-Yan at LHCb Correlated systematics needed It would be better: same phase space for p-p and p-pb 20 / 24

53 A-Z NNLO npdfs First NNLO npdf set within a GM-VFNS Charged lepton and neutrino DIS data already included Drell-Yan to come Nuclear effects in deuterium Flavor separation? When? 17xx.xxxx Carlota Andres and Pia Zurita 21 / 24

54 A-Z NNLO npdfs First NNLO npdf set within a GM-VFNS Charged lepton and neutrino DIS data already included Drell-Yan to come Nuclear effects in deuterium Flavor separation? When? 17xx.xxxx Carlota Andres and Pia Zurita 21 / 24

55 A-Z NNLO npdfs First NNLO npdf set within a GM-VFNS Charged lepton and neutrino DIS data already included Drell-Yan to come Nuclear effects in deuterium Flavor separation? When? 17xx.xxxx Carlota Andres and Pia Zurita 21 / 24

56 A-Z NNLO npdfs First NNLO npdf set within a GM-VFNS Charged lepton and neutrino DIS data already included Drell-Yan to come Nuclear effects in deuterium Flavor separation? When? 17xx.xxxx Carlota Andres and Pia Zurita 21 / 24

57 A-Z NNLO npdfs First NNLO npdf set within a GM-VFNS Charged lepton and neutrino DIS data already included Drell-Yan to come Nuclear effects in deuterium Flavor separation? When? 17xx.xxxx Carlota Andres and Pia Zurita 21 / 24

58 A-Z NNLO npdfs First NNLO npdf set within a GM-VFNS Charged lepton and neutrino DIS data already included Drell-Yan to come Nuclear effects in deuterium Flavor separation? When? 17xx.xxxx Carlota Andres and Pia Zurita 21 / 24

59 EIC: kinematics Crucial to study the low-x region!! Accardi et al., Eur. Phys. J. A52 (2016) no.9, / 24

60 EIC Accardi et al., Eur. Phys. J. A52 (2016) no.9, / 24

61 EIC Accardi et al., Eur. Phys. J. A52 (2016) no.9, 268 Never measured for e-a!! 24 / 24

62 Backup 24 / 24

63 npdfs vs. PDFs kinematics 24 / 24

64 Hessian method χ 2 expanded around the minimum χ 2 = χ i,j ( ai ai 0 ) ( Hij aj aj 0 ) = χ i z 2 i (δx ) 2 = ( ) X 2 δz i, δz i = δz+ i + δz i z i 2 PDF uncetainty sets S ± i : S 1 ± = δz± 1 (1, 0,..., 0) S ± N = δz± N (0, 0,..., N) (δx ) 2 = 1 4 i [ X (S + i ) X (S i ) ] 2 24 / 24

65 Hessian method δz ± i are defined to correspond to a fixed χ 2 Ideally χ 2 = 1 In practice: χ 2 >> 1 due to the parametrization bias: EPPS16: χ 2 = 52 DSSZ12: χ 2 = 30 ncteq15: χ 2 = 35 EPJ C / 24

66 Drell-Yan 24 / 24

67 LHeC 24 / 24