Measurement of the charm and beauty structure functions using the H1 vertex detector at HERA

Abstract

Inclusive charm and beauty cross sections are measured in e − p and e + p neutral current collisions at HERA in the kinematic region of photon virtuality 5 ≤ Q 2 ≤ 2000 GeV 2 and Bjorken scaling variable 0.0002 ≤ x ≤ 0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of 189 pb −1 . The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined with previous data and compared to QCD predictions.

Measurement of beauty and charm production in deep inelastic scattering at HERA and measurement of the beauty-quark mass

“…The same relative variations were applied to the beauty MC; δ 9 light-flavour background -the light-flavour contribution to the subtracted significance distribution includes a contribution from long-lifetime strange-hadron decays. To estimate the uncertainty due to modelling of this effect, the MC light-flavour distribution of N (S + ) − N (S − ) was scaled by ±30 % [14] and the fit was repeated;…”

“…The solid line shows the Hvqdis prediction with the ZEUS-S PDF, corrected for hadronisation effects, with the uncertainties indicated by the band; the dotted line shows the same prediction using the ABKM PDF; the dashed line shows the prediction from Rapgap scaled to match the measured integrated cross sections. [29], open triangles [27], open circles [26] and filled squares [9,11,14]). The inner error bars are the statistical uncertainty while the outer error bars represent the statistical, systematic (not including the error on the integrated luminosity) and extrapolation uncertainties added in quadrature.…”

“…Beauty and charm production in DIS has been measured using several methods by the H1 [5][6][7][8][9][10][11][12][13][14][15][16] and ZEUS [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] collaborations. All but the two most recent measurements of…”

“…For heavy-quark transverse momenta comparable to the quark mass, next-to-leading-order (NLO) QCD calculations based on the dynamical generation of the massive quarks [1][2][3][4] are expected to provide reliable predictions. Beauty and charm production in DIS has been measured using several methods by the H1 [5][6][7][8][9][10][11][12][13][14][15][16] and ZEUS [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Inclusive jet cross sections in beauty and charm events are used in the analysis presented here to extract the heavy-quark contribution to the proton structure function F 2 with high precision, and to measure the b-quark mass. For this purpose, the long lifetimes of the weakly decaying b and c hadrons, which make the reconstruction of their decay vertices possible, as well as their large masses were exploited.…”

Measurement of D ± production in deep inelastic ep scattering with the ZEUS detector at HERA

“…At HERA, several different charm-tagging techniques have been exploited to measure charm production in DIS [1][2][3][4][5][6][7][8][9][10][11][12]. Recently, a combined analysis of these data was performed [13], yielding results with both statistical and systematic uncertainties significantly reduced.…”