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Inclusive measurements at HERA from low to high x Olaf Behnke (DESY) on behalf of ISMD2013, Chicago, USA 17 th September 2013 1.

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Presentation on theme: "Inclusive measurements at HERA from low to high x Olaf Behnke (DESY) on behalf of ISMD2013, Chicago, USA 17 th September 2013 1."— Presentation transcript:

1 Inclusive measurements at HERA from low to high x Olaf Behnke (DESY) on behalf of ISMD2013, Chicago, USA 17 th September

2 2 Content Inclusive measurements: Flavour inclusive Charm production HERA Neutral current (NC) Charged current (CC) Proton Todays menu:

3 3 The HERA ep collider ( ) ~0.5 fb -1 per experiment Longitudinally polarised e ±

4 Deep inelastic scattering at HERA Get Feynman diagram Event display? k' k x P q= k-k ' Q 2 = -q 2 y = E /E e |p-cms -Resolution -Energy Relation: Q 2 = Sxy e±e± u Quark momentum S = 318 GeV NC event in H1 detector: 27.6 GeV 920 GeV 4

5 5 The HERA proton handbook Scaling violations ~ g(x,Q 2) F 2, F L F 2, F L, F 3 Bremsstrahlung of valence quarks Using all info in an NLO QCD fit (DGLAP evolution) : Data well described by DGLAP NLO QCD Charged Current JHEP 09 (2012) 61 H1PDF 2012

6 6 H1 HERA I Low Q 2 High Q 2 ZEUS H1 HERA II ZEUS NC 22 pb -1 + further data sets from low E p runs etc. e+pe+pe-pe-p NC 100 pb -1 CC 100 pb -1 NC 16 pb -1 CC 16 pb -1 Low Q 2 High Q 2 NC 30 pb -1 NC 108 pb -1 CC 108 pb -1 NC 16 pb -1 CC 16 pb -1 High Q 2 NC 182 pb -1 CC 182 pb -1 NC 150 pb -1 CC 150 pb -1 High Q 2 NC 136 pb -1 CC 132 pb -1 NC 170 pb -1 CC 175 pb -1 e+pe+pe-pe-p HERA inclusive data sets Low Q 2 ~150 GeV 2

7 7 H1 HERA I Low Q 2 High Q 2 ZEUS H1 HERA II ZEUS NC 22 pb -1 + further data sets from low E p runs etc. H1PDF 2012 JHEP 09 (2012) 61 e+pe+pe-pe-p NC 100 pb -1 CC 100 pb -1 NC 16 pb -1 CC 16 pb -1 Low Q 2 High Q 2 NC 30 pb -1 NC 108 pb -1 CC 108 pb -1 NC 16 pb -1 CC 16 pb -1 High Q 2 NC 182 pb -1 CC 182 pb -1 NC 150 pb -1 CC 150 pb -1 High Q 2 NC 136 pb -1 CC 132 pb -1 NC 170 pb -1 CC 175 pb -1 e+pe+pe-pe-p HERA inclusive data sets Low Q 2 ~150 GeV 2

8 8 H1 HERA I Low Q 2 High Q 2 ZEUS H1 HERA II ZEUS NC 22 pb -1 + further data sets from low E p runs etc. e+pe+pe-pe-p NC 100 pb -1 CC 100 pb -1 NC 16 pb -1 CC 16 pb -1 Low Q 2 High Q 2 NC 30 pb -1 NC 108 pb -1 CC 108 pb -1 NC 16 pb -1 CC 16 pb -1 High Q 2 NC 182 pb -1 CC 182 pb -1 NC 150 pb -1 CC 150 pb -1 High Q 2 NC 136 pb -1 CC 132 pb -1 NC 170 pb -1 CC 175 pb -1 e+pe+pe-pe-p HERA inclusive data sets Low Q 2 ~150 GeV 2 HERAPDF1.0 JHEP 1 (2010) 1

9 9 H1 HERA I Low Q 2 High Q 2 ZEUS H1 HERA II ZEUS NC 22 pb -1 + further data sets from low E p runs etc. e+pe+pe-pe-p NC 100 pb -1 CC 100 pb -1 NC 16 pb -1 CC 16 pb -1 Low Q 2 High Q 2 NC 30 pb -1 NC 108 pb -1 CC 108 pb -1 NC 16 pb -1 CC 16 pb -1 High Q 2 NC 182 pb -1 CC 182 pb -1 NC 150 pb -1 CC 150 pb -1 High Q 2 NC 136 pb -1 CC 132 pb -1 NC 170 pb -1 CC 175 pb -1 e+pe+pe-pe-p HERA inclusive data sets Low Q 2 ~150 GeV 2 HERAPDF1.5 H1prelim (2) ZEUS-prel (8) Now published JHEP 09 (2012) 61 Now published DESY HERAs Best! Preliminary data Not yet available ISMD

10 10 H1 HERA I Low Q 2 High Q 2 ZEUS H1 HERA II ZEUS NC 22 pb -1 + further data sets from low E p runs etc. e+pe+pe-pe-p NC 100 pb -1 CC 100 pb -1 NC 16 pb -1 CC 16 pb -1 Low Q 2 High Q 2 NC 30 pb -1 NC 108 pb -1 CC 108 pb -1 NC 16 pb -1 CC 16 pb -1 High Q 2 NC 182 pb -1 CC 182 pb -1 NC 150 pb -1 CC 150 pb -1 High Q 2 NC 136 pb -1 CC 132 pb -1 NC 170 pb -1 CC 175 pb -1 e+pe+pe-pe-p HERA inclusive data sets Low Q 2 ~150 GeV 2 Future goal: combination of all the published measurements and PDF fit

11 11 The HERAPDF1.5 family Available at NLO NNLO and now (sep. 2013) also at LO NLO Obtained with the open source QCD fit framework, see poster by P. Starovoitov

12 12 HERAPDF1.5 compared to HERA e + p NC data Data well described over huge Q 2 and x range by DGLAP NLO QCD Q 2 min

13 13 HERAPDF1.5 predictions for Tevatron Data well described by HERAPDF1.5

14 14 HERAPDF1.5 predictions for (exemplary) LHC jet data Well described by HERAPDF1.5 These data yet to be used in PDF fit, carry information on high-x gluon

15 15 Can we get PDFs just from the LHC? Not with any precision Using simulated LHC W, Z and jet data with ultimate precision estimated from current experience

16 HERA Charm production and schemes 16 Massive scheme: Q 2 ~m c 2 Massless scheme: Q 2 >>m c 2 Mixed schemes: interpolate, but how to do transition? numerous variants FFNS ZM-VFNS GM-VFNS

17 17 HERA Charm data combination Combine D*,D +,D 0, and lifetime tag data take correlated systematics fully into account ~ cc red EPJ C73 (2013) 2311

18 18 Best precision:~5% HERA Charm data combination Combine D*,D +,D 0, and lifetime tag data take correlated systematics fully into account ~ cc red EPJ C73 (2013) 2311

19 19 Combined charm data vs NLO GMVFNS EPJ C73 (2013) 2311 NLO GM-VFNS ok large theory uncertainty dominated by m c variation HERAPDF1.5: only inclusive DIS data RT standard scheme

20 20 PDF plus charm mass parameter fit EPJ C73 (2013) 2311 Various GM-VFNS: interpolate differently between massive and massless schemes different quality of charm data description for fixed M c compensate by M c opt values stabilises flavour mixture in PDF stabilises LHC predictions (W,Z) (see backup) M c = 1.4 GeV Using instead M c = M c opt Fit combined charm and inclusive DIS data GMVFN-schemes with charm pole mass M c

21 21 Impact of charm data on PDF improve sea flavour decomposition Example: RT optimal scheme EPJ C73 (2013) 2311

22 Conclusions 22 Precise combined HERA charm DIS data test heavy quark mass terms in pQCD: variable flavour number schemes: Data can separate between them, compensate by M c opt improve sea flavour decomposition Fixed flavour number scheme (not shown, see backup) : Provides the best data description Fit running m c (m c )= 1.26±0.06 GeV Further new precise ZEUS charm DIS data: D* and D+ (not shown, see backup) : Final H1 and ZEUS Neutral and Charged Current bulk data sets available since 2012 Best precisions of ~1.5% for NC data with Q 2 from few to 500 GeV 2 Data well described over large Q 2 and x range by NLO QCD Ongoing work on final HERA combination HERA Data based PDFs are essential for predictions at the LHC, we recommend HERAPDF1.5 (NNLO, NLO, now Charm production Inclusive DIS

23 Backup slides

24 24 e-p e+p ZEUS final high Q 2 HERA II results completed by e+p NC data Reduced NC cross sections PRD 87, (2013) Data well described by DGLAP NLO QCD Best precisions of ~1.5%

25 Charm production at HERA 25 Large contributions to incl. DIS Sensitive to g(x)

26 Charm contribution to DIS: F 2 cc 26

27 27 Z,W cross section predictions for LHC optimal M c reduces significantly uncertainty Z0Z0 W+W+ W-W- EPJ C73 (2013) 2311

28 28 stabilise sea flavour composition Impact of charm data on PDF Example: RT optimal scheme EPJ C73 (2013) 2311

29 29 EPJ C73 (2013) 2311 Use MS running mass NLO+ partial NNLO Very good description everywhere Combined charm data vs ABM FFNS prediction

30 30 Fit: PDF plus MS running charm mass EPJ C73 (2013) 2311 Fit combined charm and inclusive DIS data use ABM FFNS m c (m c ) = 1.26 ±0.05 exp ±0.03 mod ±0.02 s GeV PDG: ±0.025 GeV (lattice QCD + time-like processes) nice and consistent result

31 31 Brand new charm results in DIS: D* and D+ DESY DESY Consistent findings New ZEUS results will improve combination, PDF and m c fits ~ cc red


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