El aprendizaje del idioma inglés y desigualdad: formación inicial docente y propuestas curriculares para primero básico

This article is a reflection on the challenges of initial teacher training and the process of teaching English in the first year of basic education. In order to understand the context of inequality in which learning takes place in Chile, the comparative method was used to analyse the Ministry of Education's curriculum proposal for this level with that of a public school. Based on the categories identified, a questionnaire was developed and answered by 10 English teachers in order to triangulate the data. The main findings of this study address the urgency of improving teacher training programmes and the need to improve certain aspects of the curriculum in order to reduce the inequality gaps present in the curricular proposals from the initial stage.Este artículo corresponde a una reflexión sobre los desafíos de la formación inicial docente y el proceso de enseñanza del inglés en primer año de enseñanza básica. Así, con el fin de entender el contexto de desigualdad en que se aprende en Chile, se utilizó el método comparativo para analizar la propuesta curricular del Ministerio de Educación para el nivel con la de un colegio privado. A partir de las categorías identificadas, se elaboró un cuestionario respondido por 10 profesores de inglés con el propósito de triangular los datos. Los principales hallazgos de este estudio abordan la urgencia de mejorar los programas de formación docente y la necesidad de perfeccionar ciertos aspectos curriculares para reducir las brechas de desigualdad presentes en las propuestas curriculares desde la etapa inicial

Multiplicity dependence of light (anti-)nuclei production in p–Pb collisions at sNN=5.02 TeV

The measurement of the deuteron and anti-deuteron production in the rapidity range −1 < y < 0 as a function of transverse momentum and event multiplicity in p–Pb collisions at √sNN = 5.02 TeV is presented. (Anti-)deuterons are identified via their specific energy loss dE/dx and via their time-of- flight. Their production in p–Pb collisions is compared to pp and Pb–Pb collisions and is discussed within the context of thermal and coalescence models. The ratio of integrated yields of deuterons to protons (d/p) shows a significant increase as a function of the charged-particle multiplicity of the event starting from values similar to those observed in pp collisions at low multiplicities and approaching those observed in Pb–Pb collisions at high multiplicities. The mean transverse particle momenta are extracted from the deuteron spectra and the values are similar to those obtained for p and particles. Thus, deuteron spectra do not follow mass ordering. This behaviour is in contrast to the trend observed for non-composite particles in p–Pb collisions. In addition, the production of the rare 3He and 3He nuclei has been studied. The spectrum corresponding to all non-single diffractive p-Pb collisions is obtained in the rapidity window −1 < y < 0 and the pT-integrated yield dN/dy is extracted. It is found that the yields of protons, deuterons, and 3He, normalised by the spin degeneracy factor, follow an exponential decrease with mass number

Measurement of electrons from semileptonic heavy-flavour hadron decays at midrapidity in pp and Pb–Pb collisions at √sNN = 5.02 TeV

The differential invariant yield as a function of transverse momentum (pT) of electrons from semileptonic heavy-flavour hadron decays was measured at midrapidity in central (0–10%), semi-central (30–50%) and peripheral (60–80%) lead–lead (Pb–Pb) collisions at √sNN = 5.02 TeV in the pT intervals 0.5–26 GeV/c (0–10% and 30–50%) and 0.5–10 GeV/c (60–80%). The production cross section in proton–proton (pp) collisions at √s = 5.02 TeV was measured as well in 0.5 < pT < 10 GeV/c and it lies close to the upper band of perturbative QCD calculation uncertainties up to pT = 5 GeV/c and close to the mean value for larger pT. The modification of the electron yield with respect to what is expected for an incoherent superposition of nucleon–nucleon collisions is evaluated by measuring the nuclear modification factor RAA. The measurement of the RAA in different centrality classes allows in-medium energy loss of charm and beauty quarks to be investigated. The RAA shows a suppression with respect to unity at intermediate pT, which increases while moving towards more central collisions. Moreover, the measured RAA is sensitive to the modification of the parton distribution functions (PDF) in nuclei, like nuclear shadowing, which causes a suppression of the heavy-quark production at low pT in heavy-ion collisions at LHC

Coherent J/ψ\psi photoproduction at forward rapidity in ultra-peripheral Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm{NN}}}=5.02 TeV

The ALICE collaboration performed the first rapidity-differential measurement of coherent J/ψ photoproduction in ultra-peripheral Pb–Pb collisions at a center-of-mass energy $\sqrt{s_{\rm NN}}$ = 5.02 TeV. The J/ψ is detected via its dimuon decay in the forward rapidity region (−4.0 < y <−2.5 ) for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 750 $\mu$b$^{-1}$ . The cross section for coherent J/ψ production is presented in six rapidity bins. The results are compared with theoretical models for coherent J/ψ photoproduction. These comparisons indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of ψ′ to J/ψ coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons

Measurement of charged jet cross section in pppp collisions at s=5.02{\sqrt{s}=5.02} TeV

International audienceThe cross section of jets reconstructed from charged particles is measured in the transverse momentum range of 5<pT<100  GeV/c in pp collisions at the center-of-mass energy of s=5.02  TeV with the ALICE detector. The jets are reconstructed using the anti-kT algorithm with resolution parameters R=0.2, 0.3, 0.4, and 0.6 in the pseudorapidity range |η|<0.9-R. The charged jet cross sections are compared with the leading-order (LO) and to next-to-leading-order (NLO) perturbative quantum chromodynamics (pQCD) calculations. It is found that the NLO calculations agree better with the measurements. The cross section ratios for different resolution parameters are also measured. These ratios increase from low pT to high pT and saturate at high pT, indicating that jet collimation is larger at high pT than at low pT. These results provide a precision test of pQCD predictions and serve as a baseline for the measurement in Pb-Pb collisions at the same energy to quantify the effects of the hot and dense medium created in heavy-ion collisions at the LHC

Direct photon elliptic flow in Pb–Pb collisions at √sNN = 2.76 TeV

The elliptic flow of inclusive and direct photons was measured at mid-rapidity in two centrality classes 0-20% and 20-40% in Pb-Pb collisions at sNN−−−√ =2.76 TeV by ALICE. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the detector material with the e+e− pairs reconstructed in the central tracking system. The results of the two methods were combined and the direct photon elliptic flow was extracted in the transverse momentum range 0.9<pT<6.2 GeV/c. We test the hypothesis vγ,dir2≡0 for 0.9<pT<2.1 GeV/c and obtain a significance of 1.4σ for the 0-20% class and 1.0σ for the 20-40% class. A comparison to RHIC data shows a similar magnitude of the measured elliptic flow, while hydrodynamic and transport model calculations predict a smaller flow than observed

Azimuthal Anisotropy of Heavy-Flavor Decay Electrons in pp-Pb Collisions at sNN \sqrt{s_{\rm NN}} = 5.02 TeV

International audienceAngular correlations between heavy-flavor decay electrons and charged particles at midrapidity (|η|<0.8) are measured in p-Pb collisions at sNN=5.02  TeV. The analysis is carried out for the 0%–20% (high) and 60%–100% (low) multiplicity ranges. The jet contribution in the correlation distribution from high-multiplicity events is removed by subtracting the distribution from low-multiplicity events. An azimuthal modulation remains after removing the jet contribution, similar to previous observations in two-particle angular correlation measurements for light-flavor hadrons. A Fourier decomposition of the modulation results in a positive second-order coefficient (v2) for heavy-flavor decay electrons in the transverse momentum interval 1.5<pT<4  GeV/c in high-multiplicity events, with a significance larger than 5σ. The results are compared with those of charged particles at midrapidity and those of inclusive muons at forward rapidity. The v2 measurement of open heavy-flavor particles at midrapidity in small collision systems could provide crucial information to help interpret the anisotropies observed in such systems

Medium modification of the shape of small-radius jets in central Pb-Pb collisions at sNN=2.76 TeV\sqrt{s_{\mathrm {NN}}} = 2.76\,\rm{TeV}

We present the measurement of a new set of jet shape observables for track-based jets in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV. The set of jet shapes includes the first radial moment or angularity, g, the momentum dispersion, p$_{T}$D, and the difference between the leading and sub-leading constituent track transverse momentum, LeSub. These observables provide complementary information on the jet fragmentation and can constrain different aspects of the theoretical description of jet-medium interactions. The jet shapes were measured for a small resolution parameter R = 0.2 and were fully corrected to particle level. The observed jet shape modifications indicate that in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by PYTHIA calculations, which were validated with the measurements of the jet shapes in proton-proton collisions at $\sqrt{s}=7$ TeV. The comparison of the measured distributions to templates for quark and gluon-initiated jets indicates that in-medium fragmentation resembles that of quark jets in vacuum. We further argue that the observed modifications are not consistent with a totally coherent energy loss picture where the jet loses energy as a single colour charge, suggesting that the medium resolves the jet structure at the angular scales probed by our measurements (R = 0.2). Furthermore, we observe that small-R jets can help to isolate purely energy loss effects from other effects that contribute to the modifications of the jet shower in medium such as the correlated background or medium response

Charged-particle production as a function of multiplicity and transverse spherocity in pp collisions at s=5.02\sqrt{s} =5.02 and 13 TeV

We present a study of the inclusive charged-particle transverse momentum ($p_{\rm T}$) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, ${\rm d}N_{\rm ch}/{\rm d}\eta$, in pp collisions at $\sqrt{s}=5.02$ and 13 TeV covering the kinematic range $|\eta|0$). The transverse momentum spectra are reported for two multiplicity estimators covering different pseudorapidity regions. While the $p_{\rm T}$ spectra exhibit a strong dependence on multiplicity and center-of-mass energy, they show little energy dependence when normalized to the $p_{\rm T}$ spectrum for INEL$\,>0$. The behavior of the multiplicity dependent spectra from intermediate to high transverse momentum ($6 0$ pp collisions. Moreover, within uncertainties the functional form of $\langle p_{\rm T} \rangle(N_{\rm ch})$ is not affected by the spherocity selection. However, in PYTHIA 6 (tune Perugia 2011) and PYTHIA 8 (tune Monash 2013) the functional form of $\langle p_{\rm T} \rangle(N_{\rm ch})$ is modified by the spherocity selection and in particular for jet-like events, the models overestimate the average $p_{\rm T}$. The general purpose QCD Monte Carlo generator EPOS LHC gives a good description of many features of data. The observations are discussed in terms of multi-parton interactions with large momentum transfer and color reconnection.We present a study of the inclusive charged-particle transverse momentum ( $p_{\mathrm{T}}$ ) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, $\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta$ , in pp collisions at $\sqrt{s}=5.02$ and 13 TeV covering the kinematic range $|\eta |0$ ). The $p_\mathrm{T}$ spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The $p_{\mathrm{T}}$ spectra normalized to that for INEL $\,>0$ show little energy dependence. Moreover, the high- $p_{\mathrm{T}}$ yields of charged particles increase faster than the charged-particle multiplicity density. The average ${ p}_{\mathrm{T}}$ as a function of multiplicity and transverse spherocity is reported for pp collisions at $\sqrt{s}=13$  TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average $p_\mathrm{T}$ is higher (smaller) than that measured in INEL $\,>0$ pp collisions. Within uncertainties, the functional form of $\langle p_{\mathrm{T}} \rangle (N_{\mathrm{ch}})$ is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average $p_{\mathrm{T}}$ in jet-like events.We present a study of the inclusive charged-particle transverse momentum ($p_{\rm T}$) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, ${\rm d}N_{\rm ch}/{\rm d}\eta$, in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV covering the kinematic range $|\eta|0$). The $p_{\rm T}$ spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The $p_{\rm T}$ spectra normalized to that for INEL $>0$ show little energy dependence. Moreover, the high-$p_{\rm T}$ yields of charged particles increase faster than the charged-particle multiplicity density. The average $\it{p}_{\rm T}$ as a function of multiplicity and transverse spherocity is reported for pp collisions at $\sqrt{s}=13$ TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average $p_{\rm T}$ is higher (smaller) than that measured in INEL $>0$ pp collisions. Within uncertainties, the functional form of $\langle p_{\rm T} \rangle(N_{\rm ch})$ is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average $p_{\rm T}$ in jet-like events