Browsing by Subject "SATURATION"

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  • Mäntysaari, Heikki; Schenke, Björn (2020)
    We show how exclusive vector meson production off light ions can be used to probe the spatial distribution of small-x gluons in the deuteron and He-3 wave functions. In particular, we demonstrate how short-range repulsive nucleon-nucleon interactions affect the predicted coherent J/Psi production spectra. Fluctuations of the nucleon substructure are shown to have a significant effect on the incoherent cross section above vertical bar t vertical bar greater than or similar to 0.2 GeV2. By explicitly performing the Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner (JIMWLK) evolution, we predict the x dependence of coherent and incoherent cross sections in the electron-ion collider energy range. In addition to the increase of the average size of the nucleus with decreasing x, both the growth of the nucleons and subnucleonic hot spots are visible in the cross sections. The decreasing length scale of color charge fluctuations with decreasing x is also present, but may not be observable for vertical bar t vertical bar <1 GeV2, if subnucleonic spatial fluctuations are present.
  • Mäntysaari, Heikki; Mueller, Niklas; Schenke, Björn (2019)
    Experimental processes that are sensitive to partonWigner distributions provide a powerful tool to advance our understanding of proton structure. In this work, we compute gluon Wigner and Husimi distributions of protons within the color glass condensate framework, which includes a spatially dependent McLerran-Venugopalan initial configuration and the explicit numerical solution of the Jalilian-Marian-IancuMcLerran-Weigert-Leonidov-Kovner equations. We determine the leading anisotropy of the Wigner and Husimi distributions as a function of the angle between the impact parameter and transverse momentum. We study experimental signatures of these angular correlations at a proposed electron-ion collider by computing coherent diffractive dijet production cross sections in e + p collisions within the same framework. Specifically, we predict the elliptic modulation of the cross section as a function of the relative angle between the nucleon recoil and dijet transversemomentumfor a wide kinematical range. We further predict its dependence on the collision energy, which is dominated by the growth of the proton with decreasing x.
  • The ALICE collaboration; Acharya, S.; Brucken, E. J.; Chang, B.; Hilden, T. E.; Kim, D. J.; Litichevskyi, V.; Mieskolainen, M. M.; Orava, R.; Parkkila, J. E.; Rak, J.; Räsänen, S. S.; Saarinen, S.; Slupecki, M.; Snellman, T. W.; Trzaska, W. H.; Vargyas, M.; Viinikainen, J. (2019)
    The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of J/ vector mesons off proton targets in ultra-peripheral p-Pb collisions at a centre-of-mass energy per nucleon pair =5.02 TeV. The e+e- and +- decay channels are used to measure the cross section as a function of the rapidity of the J/ in the range -2.5<y<2.7, corresponding to an energy in the p centre-of-mass in the interval 40<Wp<550 GeV. The measurements, which are consistent with a power law dependence of the exclusive J/ photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.
  • The ALICE collaboration; Acharya, S.; Adamova, D.; Kim, D. J.; Krizek, F.; Novitzky, Norbert; Onnerstad, A.; Parkkila, J. E.; Rytkönen, Heidi Maria; Räsänen, Sami; Saarimäki, Oskari Antti Matti; Slupecki, M.; Trzaska, W. H. (2021)
    The first measurement of the coherent photoproduction of rho(0) vector mesons in ultra-peripheral Xe- Xe collisions at root s(NN) = 5.44 TeV is presented. This result, together with previous HERA gamma p data and gamma-Pb measurements from ALICE, describes the atomic number (A) dependence of this process, which is particularly sensitive to nuclear shadowing effects and to the approach to the black-disc limit of QCD at a semi-hard scale. The cross section of the Xe + Xe -> rho(0) + Xe + Xe process, measured at midrapidity through the decay channel rho(0)-> pi(+)pi(-), is found to be d sigma/dy = 131.5 +/- 5.6(stat.)(-16.9)(+17.5) (syst.) mb. The ratio of the continuum to resonant contributions for the production of pion pairs is also measured. In addition, the fraction of events accompanied by electromagnetic dissociation of either one or both colliding nuclei is reported. The dependence on A of cross section for the coherent rho 0 photoproduction at a centre-of-mass energy per nucleon of the gamma A system of W gamma A,n = 65 GeV is found to be consistent with a power-law behaviour sigma (gamma A -> rho(0) A) proportional to A(alpha) with a slope alpha = 0.96 +/- 0.02(syst.). This slope signals important shadowing effects, but it is still far from the behaviour expected in the black-disc limit. (C) 2021 European Organization for Nuclear Research. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.
  • Laursen, Jens Christian; Clemmensen, Kim Katrine Bjerring; Hansen, Christian Stevns; Diaz, Lars Jorge; Bordino, Marco; Groop, Per-Henrik; Frimodt-Moller, Marie; Bernardi, Luciano; Rossing, Peter (2021)
    Introduction Blood oxygen saturation is low compared with healthy controls (CONS) in the supine body position in individuals with type 1 diabetes (T1D) and has been associated with complications. Since most of daily life occurs in the upright position, it is of interest if this also applies in the standing body position. In addition, tissue oxygenation in other anatomical sites could show different patterns in T1D. Therefore, we investigated blood, arm and forehead oxygen levels in the supine and standing body positions in individuals with T1D (n=129) and CONs (n=55). Research design and methods Blood oxygen saturation was measured with pulse oximetry. Arm and forehead mixed tissue oxygen levels were measured with near-infrared spectroscopy sensors applied on the skin. Results Data are presented as least squares means +/- SEM and differences (95% Cls). Overall blood oxygen saturation was lower in T1D (CON: 97.6%+/- 0.2%; T1D: 97.0%+/--0.1 degrees/0; difference: -0.5% (95% CI -0.9% to -0.0%); p=0.034). In all participants, blood oxygen saturation increased after standing up (supine: 97.1%-+/- 0.1%; standing: 97.6%+/- 0.2%; difference: +0.6% (95% Cl 0.4% to 0.8%); p Conclusion Compared with CON, individuals with T1D exhibit possible detrimental patterns of tissue oxygen adaptation to standing, with preserved adaptation of forehead oxygenation. Further studies are needed to explore the consequences of these differences.
  • COMACARE Study Grp; Jakkula, Pekka; Reinikainen, Matti; Hästbacka, Johanna; Loisa, Pekka; Tiainen, Marjaana; Pettilä, Ville; Toppila, Jussi; Lähde, Marika; Bäcklund, Minna; Okkonen, Marjatta; Bendel, Stepani; Birkelund, Thomas; Pulkkinen, Anni; Heinonen, Jonna; Tikka, Tuukka; Skrifvars, Markus B. (2018)
    PurposeWe assessed the effects of targeting low-normal or high-normal arterial carbon dioxide tension (PaCO2) and normoxia or moderate hyperoxia after out-of-hospital cardiac arrest (OHCA) on markers of cerebral and cardiac injury.MethodsUsing a 2(3) factorial design, we randomly assigned 123 patients resuscitated from OHCA to low-normal (4.5-4.7kPa) or high-normal (5.8-6.0kPa) PaCO2 and to normoxia (arterial oxygen tension [PaO2] 10-15kPa) or moderate hyperoxia (PaO2 20-25kPa) and to low-normal or high-normal mean arterial pressure during the first 36h in the intensive care unit. Here we report the results of the low-normal vs. high-normal PaCO2 and normoxia vs. moderate hyperoxia comparisons. The primary endpoint was the serum concentration of neuron-specific enolase (NSE) 48h after cardiac arrest. Secondary endpoints included S100B protein and cardiac troponin concentrations, continuous electroencephalography (EEG) and near-infrared spectroscopy (NIRS) results and neurologic outcome at 6months.ResultsIn total 120 patients were included in the analyses. There was a clear separation in PaCO2 (p