DETERMINATION OF α_s AND m_c IN DEEP-INELASTIC SCATTERING

Abstract

We describe the determination of the strong coupling constant αs(M 2 Z ) and of the charm-quark mass mc(mc) in the MS-scheme, based on the QCD analysis of the unpolarized World deep-inelastic scattering data. At NNLO the values of αs(M 2 Z ) = 0.1134 ± 0.0011(exp) and mc(mc) = 1.24 ± 0.03(exp) +0.03 −0.02 (scale) +0.00 −0.07 (th) are obtained and are compared with other determinations, also clarifying discrepancies.

A determination of m c (m c ) from HERA data using a matched heavy-flavor scheme

“…Our results have been obtained employing the most accurate perturbative calculations presently available and will include a detailed characterization of the different sources of uncertainties on m c (m c ) from data, theory and fitting methodology. As we will show, the results are consistent with the global PDG average as well as with previous determinations based on the FFN [9,[23][24][25] and in the S-ACOT [29] schemes. 1 The uncertainty in our results turns out to be competitive with that of previous determinations based on DIS structure functions.…”

“…[24] was performed including the same exclusive charm cross-section data used in this study, it did not include the HERA1+2 combined inclusive cross-section data set which was not available at the time, but used instead the HERA combined data from run 1 only. An earlier analysis [23] used a partial charm dataset only, with correspondingly larger uncertainties, while a subsequent analysis [25] investigated the correlation between the measurement of m c (m c ) and the strong coupling constant.…”

“…In this work we will mostly concentrate on the FONLL scheme and on its implications for the determination of the charm mass. For the sake of comparison with previous studies [9,[23][24][25], a determination of the charm mass in the FFN scheme at NLO is also performed.…”

Theoretical update of the charm structure function of the proton

“…Another approach is to use the soft-gluon resummation technique [5] to derive the logarithmically enhanced NNLO terms (α 2 s ln k β , k ≤ 4), by which the terms of k = 4, 3 (and k = 2 partly) have been derived in ref. [6] ( [7]). In this contribution, we develops the latter approach, deriving all the logarithmically and/or power enhanced corrections at the NNLO by employing the resummation at the next-to-next-to leading logarithmic (NNLL) accuracy.…”

HERAFitter - an open source QCD fit framework

“…Several groups are currently involved in the PDF fitting analysis: MSTW [7], CT(EQ) [8], NNPDF [9], AB(K)M [10], GJR [11] and HERAPDF [12]. Their methods and distinguishing features are reviewed in [13,14].…”