1 =============== minutes of HERAFitter User's meeting 20.05.2013 ==================== 2 3 Meetings: 4 LHCP: poster of HERAFitter has been presented (Hayk Pirumov) 5 accepted abstracts for dedicated talks in: 6 EPS, LowX, HADRONSTRUCTURE13, QCD@LHC(agenda under preparation), 7 submitted abstract to ISMD, 8 planned to be submitted to HADRON 2013. 9 (this information can now also be accessed from HERAFitter web page). 10 11 News: 12 - positive feedback from PRC in recommendations released on 24th of May, 13 expected dedicated talk in open session in next PRC (stable release is 14 planned to be released about this time). 15 - from 1st of May Hayk Prumov is a librarian for HERAFitter package 16 - two bugs found recently in the HETAFitter-0.3.0 version, as a result 17 the bug fix release HERAFitter-0.3.1 is foreseen next week. 18 - the target for stable release is September-October, some improvements 19 to manual already done but still more required. Release will be 20 supplemented with the short paper. 21 22 Talks: 23 M.Botje "QCD+QED evolution in QCDNUM": 24 work in progress (coupled evolution routine, new memory layout, upgrade 25 of the internal memory and write-up are done, on the list are update of 26 the users interface and backward evolution). The test version of 27 QCDNUM 17-01-0a is foreseen first. 28 29 F.Olness "Comments on merging of FF and VFNS schemes": 30 presented proposal of number of flavour (Nf) dependent PDFs and alpha_s, 31 where user can choose when to switch between Nf and Nf+1 (one of the main 32 arguments is that matching is not necessary has to be done at scale~m_quark). 33 Example: charm production at HERA, if at sufficient low Q2 (~10GeV2) the 34 gluon with Nf=5 and Nf=3 can be rescaled by constant factor as a function 35 of x (at higher scales the scaling is no longer a constant). 36 Such PDFs could be useful for studies of the b quark density function at HERA. 37 38 M. Guzzi "News from the theory side": 39 - significant progress on ttbar differential cross section calculations 40 at approx NNLO+NNLL were presented and planned to be included into 41 HERAFitter. Some cross checks and additions (possibility of varying inputs 42 like mT, scales, alpha_s, ...) currently are ongoing. 43 - issues related to the extraction of the charm quark mass from PDF fits 44 discussed in details (in a context of the discussion from DIS13 conference). 45 Main differences between recently HERA published mC versus the CTEQ 46 determination includes differences in the PDF uncertainty determination, 47 the chi2 criteria used in the fit, different definitions of the "NLO", "NNLO" 48 in different HQ schemes, fluctuations in the PDF fits (can be caused by 49 numerical instabilities or fitting methodology), MSbar to the pole mass 50 conversion (fit is sensitive to the order of the conversion), etc.. 51 52 The doodle for next HERAFitter User's meeting is set (end of June).
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