The production of the $\Lambda $(1520) baryonic resonance has been measured at midrapidity in inelastic pp collisions at $\sqrt{s} = 7\ \hbox {TeV}$ and in p–Pb collisions at $\sqrt{s_{\mathrm{NN}}} ...= 5.02\ \hbox {TeV}$ for non-single diffractive events and in multiplicity classes. The resonance is reconstructed through its hadronic decay channel $\Lambda $(1520) $\rightarrow \hbox {pK}^{-}$ and the charge conjugate with the ALICE detector. The integrated yields and mean transverse momenta are calculated from the measured transverse momentum distributions in pp and p–Pb collisions. The mean transverse momenta follow mass ordering as previously observed for other hyperons in the same collision systems. A Blast-Wave function constrained by other light hadrons ($\pi $, K, $\hbox {K}_{\mathrm{S}}^0$, p, $\Lambda $) describes the shape of the $\Lambda $(1520) transverse momentum distribution up to $3.5\ \hbox {GeV}/c$ in p–Pb collisions. In the framework of this model, this observation suggests that the $\Lambda $(1520) resonance participates in the same collective radial flow as other light hadrons. The ratio of the yield of $\Lambda (1520)$ to the yield of the ground state particle $\Lambda $ remains constant as a function of charged-particle multiplicity, suggesting that there is no net effect of the hadronic phase in p–Pb collisions on the $\Lambda $(1520) yield.
GLP-1 is an insulinotropic hormone that synergistically with glucose gives rise to an increased insulin response. Its secretion is increased following a meal and it is thus of interest to describe ...the secretion of this hormone following an oral glucose tolerance test (OGTT). The aim of this study was to build a mechanism-based population model that describes the time course of total GLP-1 and provides indices for capability of secretion in each subject. The goal was thus to model the secretion of GLP-1, and not its effect on insulin production. Single 75 g doses of glucose were administered orally to a mixed group of subjects ranging from healthy volunteers to patients with type 2 diabetes (T2D). Glucose, insulin, and total GLP-1 concentrations were measured. Prior population data analysis on measurements of glucose and insulin were performed in order to estimate the glucose absorption rate. The individual estimates of absorption rate constants were used in the model for GLP-1 secretion. Estimation of parameters was performed using the FOCE method with interaction implemented in NONMEM VI. The final transit/indirect-response model obtained for GLP-1 production following an OGTT included two stimulation components (fast, slow) for the zero-order production rate. The fast stimulation was estimated to be faster than the glucose absorption rate, supporting the presence of a proximal–distal loop for fast secretion from
l
-cells. The fast component (
st
3
= 8.64·10
−5
mg
−1
) was estimated to peak around 25 min after glucose ingestion, whereas the slower component (
st
4
= 26.2·10
−5
mg
−1
) was estimated to peak around 100 min. Elimination of total GLP-1 was characterised by a first-order loss. The individual values of the early phase GLP-1 secretion parameter (
st
3
) were correlated (
r
= 0.52) with the AUC(0–60 min.) for GLP-1. A mechanistic population model was successfully developed to describe total GLP-1 concentrations over time observed after an OGTT. The model provides indices related to different mechanisms of subject abilities to secrete GLP-1. The model provides a good basis to study influence of different demographic factors on these components, presented mainly by indices of the fast- and slow phases of GLP-1 response.
The production cross section of inclusive isolated photons has been measured by the ALICE experiment at the CERN LHC in pp collisions at a centre-of-momentum energy of Formula omitted 7 TeV. The ...measurement is performed with the electromagnetic calorimeter EMCal and the central tracking detectors, covering a range of Formula omitted in pseudorapidity and a transverse momentum range of Formula omitted. The result extends the Formula omitted coverage of previously published results of the ATLAS and CMS experiments at the same collision energy to smaller Formula omitted. The measurement is compared to next-to-leading order perturbative QCD calculations and to the results from the ATLAS and CMS experiments. All measurements and theory predictions are in agreement with each other.
We present a study of the inclusive charged-particle transverse momentum ( Formula omitted) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, Formula omitted, in ...pp collisions at Formula omitted and 13 TeV covering the kinematic range Formula omitted and Formula omitted GeV/c. The results are presented for events with at least one charged particle in Formula omitted (INEL Formula omitted). The Formula omitted spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The Formula omitted spectra normalized to that for INEL Formula omitted show little energy dependence. Moreover, the high- Formula omitted yields of charged particles increase faster than the charged-particle multiplicity density. The average Formula omitted as a function of multiplicity and transverse spherocity is reported for pp collisions at Formula omitted TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average Formula omitted is higher (smaller) than that measured in INEL Formula omitted pp collisions. Within uncertainties, the functional form of Formula omitted is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average Formula omitted in jet-like events.
The pseudorapidity density of charged particles, Formula omitted, in p-Pb collisions has been measured at a centre-of-mass energy per nucleon-nucleon pair of Formula omitted = 8.16 TeV at ...mid-pseudorapidity for non-single-diffractive events. The results cover 3.6 units of pseudorapidity, Formula omitted. The Formula omitted value is Formula omitted at Formula omitted. This quantity divided by Formula omitted / 2 is Formula omitted, where Formula omittedis the average number of participating nucleons, is 9.5% higher than the corresponding value for p-Pb collisions at Formula omitted = 5.02 TeV. Measurements are compared with models based on different mechanisms for particle production. All models agree within uncertainties with data in the Pb-going side, while HIJING overestimates, showing a symmetric behaviour, and EPOS underestimates the p-going side of the Formula omitted distribution. Saturation-based models reproduce the distributions well for Formula omitted. The Formula omitted is also measured for different centrality estimators, based both on the charged-particle multiplicity and on the energy deposited in the Zero-Degree Calorimeters. A study of the implications of the large multiplicity fluctuations due to the small number of participants for systems like p-Pb in the centrality calculation for multiplicity-based estimators is discussed, demonstrating the advantages of determining the centrality with energy deposited near beam rapidity.
First results on Formula omitted, Formula omitted and K/p fluctuations are obtained with the ALICE detector at the CERN LHC as a function of centrality in Formula omitted collisions at Formula ...omitted. The observable Formula omitted, which is defined in terms of the moments of particle multiplicity distributions, is used to quantify the magnitude of dynamical fluctuations of relative particle yields and also provides insight into the correlation between particle pairs. This study is based on a novel experimental technique, called the Identity Method, which allows one to measure the moments of multiplicity distributions in case of incomplete particle identification. The results for Formula omitted show a change of sign in Formula omitted from positive to negative towards more peripheral collisions. For central collisions, the results follow the smooth trend of the data at lower energies and Formula omitted exhibits a change in sign for Formula omitted and K/p.
We report on the measurement of the inclusive J/ Formula omitted polarization parameters in pp collisions at a center of mass energy Formula omitted TeV with the ALICE detector at the LHC. The ...analysis is based on a data sample corresponding to an integrated luminosity of 1.23 pb Formula omitted. J/ Formula omitted resonances are reconstructed in their di-muon decay channel in the rapidity interval Formula omitted and over the transverse-momentum interval Formula omitted Formula omitted. The three polarization parameters ( Formula omitted, Formula omitted, Formula omitted) are measured as a function of Formula omitted both in the helicity and Collins-Soper reference frames. The measured J/ Formula omitted polarization parameters are found to be compatible with zero within uncertainties, contrary to expectations from all available predictions. The results are compared with the measurement in pp collisions at Formula omitted TeV.
Neutral pion and Formula omitted meson invariant differential yields were measured in non-single diffractive p-Pb collisions at Formula omitted = 5.02 TeV with the ALICE experiment at the CERN LHC. ...The analysis combines results from three complementary photon measurements, utilizing the PHOS and EMCal calorimeters and the Photon Conversion Method. The invariant differential yields of Formula omitted and Formula omitted meson inclusive production are measured near mid-rapidity in a broad transverse momentum range of Formula omitted and Formula omitted, respectively. The measured Formula omitted ratio increases with Formula omitted and saturates for Formula omitted > 4 Formula omitted at Formula omitted. A deviation from Formula omitted scaling is observed for Formula omitted 2 Formula omitted. The measured Formula omitted ratio is consistent with previous measurements from proton-nucleus and pp collisions over the full Formula omitted range. The measured Formula omitted ratio at high Formula omitted also agrees within uncertainties with measurements from nucleus-nucleus collisions. The Formula omitted and Formula omitted yields in p-Pb relative to the scaled pp interpolated reference, Formula omitted, are presented for Formula omitted 20 Formula omitted and Formula omitted 20 Formula omitted, respectively. The results are compared with theoretical model calculations. The values of Formula omitted are consistent with unity for transverse momenta above 2 Formula omitted. These results support the interpretation that the suppressed yield of neutral mesons measured in Pb-Pb collisions at LHC energies is due to parton energy loss in the hot QCD medium.
Formula omitted meson measurements provide insight into strangeness production, which is one of the key observables for the hot medium formed in high-energy heavy-ion collisions. ALICE measured ...Formula omitted production through its decay in muon pairs in Pb-Pb collisions at Formula omitted TeV in the intermediate transverse momentum range Formula omitted GeV/c and in the rapidity interval Formula omitted. The Formula omitted yield was measured as a function of the transverse momentum and collision centrality. The nuclear modification factor was obtained as a function of the average number of participating nucleons. Results were compared with the ones obtained via the kaon decay channel in the same Formula omitted range at midrapidity. The values of the nuclear modification factor in the two rapidity regions are in agreement within uncertainties.
A measurement of beauty hadron production at mid-rapidity in proton-lead collisions at a nucleon–nucleon centre-of-mass energy sNN=5.02 TeV is presented. The semi-inclusive decay channel of beauty ...hadrons into J/ψ is considered, where the J/ψ mesons are reconstructed in the dielectron decay channel at mid-rapidity down to transverse momenta of 1.3 GeV/c. The bb¯ production cross section at mid-rapidity, dσbb¯/dy, and the total cross section extrapolated over full phase space, σbb¯, are obtained. This measurement is combined with results on inclusive J/ψ production to determine the prompt J/ψ cross sections. The results in p–Pb collisions are then scaled to expectations from pp collisions at the same centre-of-mass energy to derive the nuclear modification factor RpPb, and compared to models to study possible nuclear modifications of the production induced by cold nuclear matter effects. RpPb is found to be smaller than unity at low pT for both J/ψ coming from beauty hadron decays and prompt J/ψ.
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