Evidence of quasi-partonic higher-twist effects in deep inelastic scattering at HERA at moderate Q2Q^2

The combined HERA data for the inclusive deep inelastic scattering (DIS) cross sections for the momentum transfer $Q^2 > 1$ GeV$^2$ are fitted within the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) framework at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) accuracy, complemented by a QCD-inspired parameterisation of twist 4 corrections. A modified form of the input parton density functions is also included, motivated by parton saturation mechanism at small Bjorken $x$ and at a low scale. These modifications lead to a significant improvement of the data description in the region of low $Q^2$. For the whole data sample, the new benchmark NNLO DGLAP fit yields $\chi^2$ / d.o.f. $\simeq 1.2$ to be compared to 1.5 resulting from the standard NNLO DGLAP fit. We discuss the results in the context of the parton saturation picture and describe the impact of the higher-twist corrections on the derived parton density functions. The resulting description of the longitudinal proton structure function $F_L$ is consistent with the HERA data. Our estimates of higher-twist contributions to the proton structure functions are comparable to the leading-twist contributions at low $Q^2 \simeq 2$ GeV$^2$ and $x \simeq 10^{-5}$. The $x$-dependence of the twist 4 corrections obtained from the best fit is consistent with the leading twist 4 quasi-partonic operators, corresponding to an exchange of four interacting gluons in the $t$-channel

Structure Functions and Parton Densities: a Session Summary

Studies of fragmentation and parton density functions are a core component of research in high energy particle and nuclear physics. These quantities are inherently interesting as a probe of the quantum nature of the strong force and are also essential ingredients to additional studies in high energy scattering experiments. These proceedings provide an overview of the state of the art in this area, as presented at the Deep-Inelastic Scattering Conference in the Spring of 2021

Impact of inclusive electron ion collider data on collinear parton distributions

A study is presented of the impact of updated simulated inclusive electron ion collider deep inelastic scattering data on the determination of the proton and nuclear parton distribution functions (PDFs) at next-to-next-to-leading and next-to-leading order in QCD, respectively. The influence on the proton PDFs is evaluated relative to the HERAPDF2.0 set, which uses inclusive HERA data only, and also relative to the global fitting approach of the MSHT20 PDFs. The impact on nuclear PDFs is assessed relative to the EPPS21 global fit and is presented in terms of nuclear modification ratios. For all cases studied, significant improvements in the PDF uncertainties are observed for several parton species. The most striking impact occurs for the nuclear PDFs in general and for the region of high Bjorken x in the proton PDFs, particularly for the valence quark distributions

Extraction of the strong coupling with HERA and EIC inclusive data

Sensitivity to the strong coupling $$\alpha _S(M^2_Z)$$ is investigated using existing Deep Inelastic Scattering data from HERA in combination with projected future measurements from the Electron Ion Collider (EIC) in a next-to-next-to-leading order QCD analysis. A potentially world-leading level of precision is achievable when combining simulated inclusive neutral current EIC data with inclusive charged and neutral current measurements from HERA, with or without the addition of HERA inclusive jet and dijet data. The result can be obtained with substantially less than one year of projected EIC data at the lower end of the EIC centre-of-mass energy range. Some questions remain over the magnitude of uncertainties due to missing higher orders in the theoretical framework

Impact of Inclusive Electron Ion Collider Data on Collinear Parton Distributions

A study is presented of the impact of simulated inclusive Electron Ion Collider Deep Inelastic Scattering data on the determination of the proton and nuclear parton distribution functions (PDFs) at next-to-next-to-leading and next-to-leading order in QCD, respectively. The influence on the proton PDFs is evaluated relative to the HERAPDF2.0 set, which uses inclusive HERA data only, and also relative to the global fitting approach of the MSHT20 PDFs. The impact on nuclear PDFs is assessed relative to the EPPS21 global fit and is presented in terms of nuclear modification ratios. For all cases studied, significant improvements in the PDF uncertainties are observed for several parton species. The most striking impact occurs for the nuclear PDFs in general and for the region of high Bjorken $x$ in the proton PDFs, particularly for the valence quark distributions.Comment: 20 pages, 10 figures, 1 Tabl

Extraction of the strong coupling with HERA and EIC inclusive data

Sensitivity to the strong coupling $\alpha_S(M^2_Z)$ is investigated using existing Deep Inelastic Scattering data from HERA in combination with projected future measurements from the Electron Ion Collider (EIC) in a next-to-next-to-leading order QCD analysis. A potentially world-leading level of precision is achievable when combining simulated inclusive neutral current EIC data with inclusive charged and neutral current measurements from HERA, with or without the addition of HERA inclusive jet and dijet data. The result can be obtained with substantially less than one year of projected EIC data at the lower end of the EIC centre-of-mass energy range. Some questions remain over the magnitude of uncertainties due to missing higher orders in the theoretical framework.Comment: 12 pages, 4 figure

Technical-efficiency analysis of end-of-life care in long-term care facilities within Europe : a cross-sectional study of deceased residents in 6 EU countries (PACE)

Background : An ageing population in the EU leads to a higher need of long-term institutional care at the end of life. At the same time, healthcare costs rise while resources remain limited. Consequently, an urgency to extend our knowledge on factors affecting efficiency of long-term care facilities (LTCFs) arises. This study aims to investigate and explain variation in technical efficiency of end-of-life care within and between LTCFs of six EU countries: Belgium (Flanders), England, Finland, Italy, the Netherlands and Poland. In this study, technical efficiency reflects the LTCFs' ability to obtain maximal quality of life (QoL) and quality of dying (QoD) for residents from a given set of resource inputs (personnel and capacity). Methods : Cross-sectional data were collected by means of questionnaires on deceased residents identified by LTCFs over a three-month period. An output-oriented data-envelopment analysis (DEA) was performed, producing efficiency scores, incorporating personnel and capacity as input and QoL and QoD as output. Scenario analysis was conducted. Regression analysis was performed on explanatory (country, LTCF type, ownership, availability of palliative care and opioids) and case mix (disease severity) variables. Results : 133 LTCFs of only one type (onsite nurses and offsite GPs) were considered in order to reduce heterogeneity. Variation in LTCF efficiency was found across as well as within countries. This variation was not explained by country, ownership, availability of palliative care or opioids. However, in the 'hands-on care at the bedside' scenario, i.e. only taking into account nursing and care assistants as input, Poland (p = 0.00) and Finland (p = 0.04) seemed to be most efficient. Conclusions : Efficiency of LTCFs differed extensively across as well as within countries, indicating room for considerable efficiency improvement. Our findings should be interpreted cautiously, as comprehensive comparative EU-wide research is challenging as it is influenced by many factors

Decreased costs and retained QoL due to the ‘PACE Steps to Success’ intervention in LTCFs : cost-effectiveness analysis of a randomized controlled trial

BACKGROUND: The number of residents in long-term care facilities (LTCFs) in need of palliative care is growing in the Western world. Therefore, it is foreseen that significantly higher percentages of budgets will be spent on palliative care. However, cost-effectiveness analyses of palliative care interventions in these settings are lacking. Therefore, the objective of this paper was to assess the cost-effectiveness of the 'PACE Steps to Success' intervention. PACE (Palliative Care for Older People) is a 1-year palliative care programme aiming at integrating general palliative care into day-to-day routines in LTCFs, throughout seven EU countries. METHODS: A cluster RCT was conducted. LTCFs were randomly assigned to intervention or usual care. LTCFs reported deaths of residents, about whom questionnaires were filled in retrospectively about resource use and quality of the last month of life. A health care perspective was adopted. Direct medical costs, QALYs based on the EQ-5D-5L and costs per quality increase measured with the QOD-LTC were outcome measures. RESULTS: Although outcomes on the EQ-5D-5L remained the same, a significant increase on the QOD-LTC (3.19 points, p value 0.00) and significant cost-savings were achieved in the intervention group (€983.28, p value 0.020). The cost reduction mainly resulted from decreased hospitalization-related costs (€919.51, p value 0.018). CONCLUSIONS: Costs decreased and QoL was retained due to the PACE Steps to Success intervention. Significant cost savings and improvement in quality of end of life (care) as measured with the QOD-LTC were achieved. A clinically relevant difference of almost 3 nights shorter hospitalizations in favour of the intervention group was found. This indicates that timely palliative care in the LTCF setting can prevent lengthy hospitalizations while retaining QoL. In line with earlier findings, we conclude that integrating general palliative care into daily routine in LTCFs can be cost-effective. TRIAL REGISTRATION: ISRCTN14741671