Search results for " parto"

Applicability of pion-nucleus Drell-Yan data in global analysis of nuclear parton distribution functions

2017

Despite the success of modern nuclear parton distribution functions (nPDFs) in describing nuclear hard-process data, they still suffer from large uncertainties. One of the poorly constrained features is the possible asymmetry in nuclear modifications of valence $u$ and $d$ quarks. We study the possibility of using pion-nucleus Drell-Yan dilepton data as a new constraint in the global analysis of nPDFs. We find that the nuclear cross-section ratios from the NA3, NA10 and E615 experiments can be used without imposing significant new theoretical uncertainties and, in particular, that these datasets may have some constraining power on the $u$/$d$ -asymmetry in nuclei.

DETERMINATION OF ALPHA-S FROM THE SCALING VIOLATION IN THE FRAGMENTATION FUNCTIONS IN E+E- ANNIHILATION

1993

A determination of the hadronic fragmentation functions of the Z0 boson is presented from a study of the inclusive hadron production with the DELPHI detector at LEP. These fragmentation functions were compared with the ones at lower energies, thus covering data in a large kinematic range: 196 less-than-or-equal-to Q2 less-than-or-equal-to 8312 GeV2 and x (= p(h)/E(beam)) > 0.08. A large scaling violation was observed, which was used to extract the strong coupling constant in second order QCD: alpha(s)(M(Z)) = 0.118 +/- 0.005. The corresponding QCD scale for five quark flavours is: LAMBDA(MS)(5)BAR = 230 +/- 60 MeV.

Quark and gluon distributions and $\alpha_{s}$ from nucleon structure functions at low $x$

1993

Abstract The Q2 dependence of the structure functions F2p and F2d recently measured by the NMC is compared with the predictions of perturbative QCD at next-to-leading order. Good agreement is observed, leading to accurate determinations of the quark and gluon distributions in the range 0.008 ⩽ × ⩽ 0.5. The strong coupling constant is measured from the low x data; the result agrees with previous determinations.

Parton distributions and lattice QCD calculations: A community white paper

2018

Progress in particle and nuclear physics 100, 107 - 160 (2018). doi:10.1016/j.ppnp.2018.01.007

Tevatron constraints on models of the Higgs boson with exotic spin and parity using decays to bottom-antibottom quark pairs.

2015

et al.

EPPS16: Nuclear parton distributions with LHC data

2017

We introduce a global analysis of collinearly factorized nuclear parton distribution functions (PDFs) including, for the first time, data constraints from LHC proton-lead collisions. In comparison to our previous analysis, EPS09, where data only from charged-lepton-nucleus deep inelastic scattering (DIS), Drell-Yan (DY) dilepton production in proton-nucleus collisions and inclusive pion production in deuteron-nucleus collisions were the input, we now increase the variety of data constraints to cover also neutrino-nucleus DIS and low-mass DY production in pion-nucleus collisions. The new LHC data significantly extend the kinematic reach of the data constraints. We now allow much more freedom…

Three-Dimensional parton structure of light nuclei

2017

Two promising directions beyond inclusive deep inelastic scattering experiments, aimed at unveiling the three dimensional structure of the bound nucleon, are reviewed, considering in particular the $^3$He nucleus. The 3D structure in coordinate space can be accessed through deep exclusive processes, whose non-perturbative part is encoded in generalized parton distributions (GPDs). In this way, the distribution of partons in the transverse plane can be obtained. As an example, coherent deeply virtual Compton scattering (DVCS) off $^3$He nuclei, important to access the neutron GPDs, will be discussed. In Impulse Approximation (IA), the sum of two GPDs of $^3$He, $H$ and $E$, at low momentum t…

La vita prenatale, il parto e il neonato

2007

Flavour Separation of Helicity Distributions from Deep Inelastic Muon-Deuteron Scattering

2009

We present a LO evaluation of helicity densities of valence, \Delta u_v+\Delta d_v, non-strange sea, \Delta\bar{u}+\Delta\bar{d}, and strange quarks, \Delta s (assumed to be equal to \Delta\bar{s}). They have been obtained from the inclusive asymmetry A_{3,d} and the semi-inclusive asymmetries A^{\pi+}_{1,d}, A^{\pi-}_{1,d}, A^{K+}_{1,d}, A^{K-}_{1,d} measured in polarised deep inelastic muon-deuteron scattering. The full deuteron statistics of COMPASS (years 2002-2004 and 2006) has been used. The data cover the range Q^2 > 1 (GeV/c)^2 and 0.004<x<0.3. Both non-strange densities are found to be in a good agreement with previous measurements. The distribution of \Delta s(x) is compatible wit…

Impiego dell'atosiban nella minaccia di parto prematuro

2006

È stato condotto uno studio prospettico su 66 gravide con lo scopo di vlutare l'efficacia e la sicurezza dell'atosiban nel trattamento della minaccia di parto pretermine. L'efficacia tocolitica è stata valutata in termini di numero di donne che non hanno parrorito dopo 48 ore e dopo 7 giorni dall'inizio della terapia. La sicurezza del farmaco, invece, in termini di effetti collaterali materni e morbilità neonatale. Le pazienti che presentavano contrazioni uterine intense e persistenti (3 ogni 10 minuti) sono state suddivise in base alle modificazioni del collo in 3 gruppi. Il 1 gruppo è composto da 20 gravide con lunghezza del collo compresa tra 25-35 mm, il II gruppo è composto da 30 gravi…