| Article | |
| Report number | arXiv:1802.00064 ; DESY-18-017 |
| Title | Impact of low-$x$ resummation on QCD analysis of HERA data |
| Author(s) |
Abdolmaleki, Hamed (Semnan U.) ; Bertone, Valerio (Vrije U., Amsterdam ; NIKHEF, Amsterdam) ; Britzger, Daniel (Heidelberg U.) ; Camarda, Stefano (CERN) ; Cooper-Sarkar, Amanda (Oxford U.) ; Giuli, Francesco (Oxford U.) ; Glazov, Alexander (DESY) ; Kusina, Aleksander (Cracow, INP) ; Luszczak, Agnieszka (DESY ; Cracow Tech. U.) ; Olness, Fred (Southern Methodist U.) ; Sapronov, Andrey (Dubna, JINR ; Troitsk, TRINITY) ; Shvydkin, Pavel (Dubna, JINR ; Troitsk, TRINITY) ; Wichmann, Katarzyna (DESY) ; Zenaiev, Oleksandr (DESY) ; Bonvini, Marco (INFN, Rome) |
| Publication | 2018-08-03 |
| Imprint | 2018-01-31 |
| Number of pages | 14 |
| Note | 14 pages, 12 figures. Additional studies and various improvements. EPJC version |
| In: | Eur. Phys. J. C 78 (2018) 621 |
| DOI | 10.1140/epjc/s10052-018-6090-8 |
| Subject category | hep-ph ; Particle Physics - Phenomenology |
| Abstract | Fits to the final combined HERA deep-inelastic scattering cross-section data within the conventional DGLAP framework of QCD have shown some tension at low $x$ and low $Q^2$. A resolution of this tension incorporating $\ln(1/x)$-resummation terms into the HERAPDF fits is investigated using the xFitter program. The kinematic region where this resummation is important is delineated. Such high-energy resummation not only gives a better description of the data, particularly of the longitudinal structure function $F_L$, it also results in a gluon PDF which is steeply rising at low $x$ for low scales, $Q^2 \simeq 2.5$ GeV$^2$, contrary to the fixed-order NLO and NNLO gluon PDF. |
| Copyright/License | publication: (License: CC-BY-4.0) preprint: (License: arXiv nonexclusive-distrib 1.0) |
Corresponding record in: Inspire
Element opprettet 2018-03-08, sist endret 2023-11-25
Eksterne lenker:
00037 The up valence PDF $xu_v$, the gluon PDF $xg$ and the total singlet PDF $x\Sigma$ for the final fits with (NNLO+NLL$x$) and without (NNLO) $\ln(1/x)$ resummation.
00027 The up valence PDF $xu_v$, the gluon PDF $xg$ and the total singlet PDF $x\Sigma$ for each of the 4 steps outlined in the text.
00035 The up valence PDF $xu_v$, the gluon PDF $xg$ and the total singlet PDF $x\Sigma$ for each of the 4 steps outlined in the text.
00033 The up valence PDF $xu_v$, the gluon PDF $xg$ and the total singlet PDF $x\Sigma$ for the final fits with (NNLO+NLL$x$) and without (NNLO) $\ln(1/x)$ resummation.
00029 The HERA NC $E_p= 920$~GeV data compared to the fits with and without $\ln(1/x)$ resummation for the $Q^2 = 3.5$ and $4.5$~GeV$^2$ bins.
00025 The HERA NC $E_p= 920$~GeV data compared to the fits with and without $\ln(1/x)$ resummation for the $Q^2 = 3.5$ and $4.5$~GeV$^2$ bins.
00026 The charm PDF at $x=10^{-4}$ as a function of the factorisation scale $\mu$ for different values of the charm threshold $\mu_c = \kappa_c m_c$, with $\kappa_c=1.12,1.5,2,2.5$. The plots show the effect of the matching at NNLO (upper plot) and at NNLO+NLL$x$ (lower plot).
00032 Scatter plot of the low-$x$ and low-$Q^2$ kinematic region covered by the HERA1+2 inclusive data and charm data at $E_p= 920$~GeV. The green shaded area indicates the region in which $\ln(1/x)$ resummation has a significant effect.
00042 The resummed splitting functions at NNLO+NLL$x$ (solid) compared to fixed order at LO (dotted), NLO (dashed) and NNLO (dot-dot-dashed) for $P_{gg}$ (upper curves) and $P_{qg}$ (lower curves) as a function of $x$. The plots are at $\alpha_S=0.28$ (corresponding to $Q^2\sim 4$~GeV$^2$) and $n_f=4$.
00036 The $\chi^2$/d.o.f. as a function of $Q^2_{\rm min}$ (left), $x_{\rm min}$ (center), and $y_{\rm max}$ (right). Each plot reports also the number of degrees of freedom at the extremities of each profile.
00043 The $\chi^2$/d.o.f. as a function of $Q^2_{\rm min}$ (left), $x_{\rm min}$ (center), and $y_{\rm max}$ (right). Each plot reports also the number of degrees of freedom at the extremities of each profile.
00031 The $\chi^2$/d.o.f. as a function of $Q^2_{\rm min}$ (left), $x_{\rm min}$ (center), and $y_{\rm max}$ (right). Each plot reports also the number of degrees of freedom at the extremities of each profile.
00037 The up valence PDF $xu_v$, the gluon PDF $xg$ and the total singlet PDF $x\Sigma$ for the final fits with (NNLO+NLL$x$) and without (NNLO) $\ln(1/x)$ resummation.00027 The up valence PDF $xu_v$, the gluon PDF $xg$ and the total singlet PDF $x\Sigma$ for each of the 4 steps outlined in the text.00035 The up valence PDF $xu_v$, the gluon PDF $xg$ and the total singlet PDF $x\Sigma$ for each of the 4 steps outlined in the text.00033 The up valence PDF $xu_v$, the gluon PDF $xg$ and the total singlet PDF $x\Sigma$ for the final fits with (NNLO+NLL$x$) and without (NNLO) $\ln(1/x)$ resummation.00029 The HERA NC $E_p= 920$~GeV data compared to the fits with and without $\ln(1/x)$ resummation for the $Q^2 = 3.5$ and $4.5$~GeV$^2$ bins.00025 The HERA NC $E_p= 920$~GeV data compared to the fits with and without $\ln(1/x)$ resummation for the $Q^2 = 3.5$ and $4.5$~GeV$^2$ bins.00026 The charm PDF at $x=10^{-4}$ as a function of the factorisation scale $\mu$ for different values of the charm threshold $\mu_c = \kappa_c m_c$, with $\kappa_c=1.12,1.5,2,2.5$. The plots show the effect of the matching at NNLO (upper plot) and at NNLO+NLL$x$ (lower plot).00032 Scatter plot of the low-$x$ and low-$Q^2$ kinematic region covered by the HERA1+2 inclusive data and charm data at $E_p= 920$~GeV. The green shaded area indicates the region in which $\ln(1/x)$ resummation has a significant effect.00042 The resummed splitting functions at NNLO+NLL$x$ (solid) compared to fixed order at LO (dotted), NLO (dashed) and NNLO (dot-dot-dashed) for $P_{gg}$ (upper curves) and $P_{qg}$ (lower curves) as a function of $x$. The plots are at $\alpha_S=0.28$ (corresponding to $Q^2\sim 4$~GeV$^2$) and $n_f=4$.00036 The $\chi^2$/d.o.f. as a function of $Q^2_{\rm min}$ (left), $x_{\rm min}$ (center), and $y_{\rm max}$ (right). Each plot reports also the number of degrees of freedom at the extremities of each profile.00043 The $\chi^2$/d.o.f. as a function of $Q^2_{\rm min}$ (left), $x_{\rm min}$ (center), and $y_{\rm max}$ (right). Each plot reports also the number of degrees of freedom at the extremities of each profile.00031 The $\chi^2$/d.o.f. as a function of $Q^2_{\rm min}$ (left), $x_{\rm min}$ (center), and $y_{\rm max}$ (right). Each plot reports also the number of degrees of freedom at the extremities of each profile.