63 research outputs found

    Dose–response effects of oral guanidinoacetic acid on serum creatine, homocysteine and B vitamins levels

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    Methods: Forty-eight healthy volunteers participated in the randomized, placebo-controlled, double-blind, repeated-measure study. At baseline, after 1, 2, 4 and 6 weeks, participants provided both fasting blood samples and 24-h urine

    Energy dependence of coherent photonuclear production of J/ψ mesons in ultra-peripheral Pb-Pb collisions at sNN \sqrt{{\textrm{s}}_{\textrm{NN}}} = 5.02 TeV

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    The cross section for coherent photonuclear production of J/ψ is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of sNN \sqrt{{\textrm{s}}_{\textrm{NN}}} = 5.02 TeV. Cross sections are presented in five different J/ψ rapidity ranges within |y| < 4, with the J/ψ reconstructed via its dilepton decay channels. In some events the J/ψ is not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range 17 < WγPb,n_{γ Pb,n} < 920 GeV, where WγPb,n_{γ Pb,n} is the centre-of-mass energy per nucleon of the γPb system. This range corresponds to a Bjorken-x interval spanning about three orders of magnitude: 1.1 × 105^{−5} < x < 3.3 × 102^{−2}. In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies

    Study of the p-p-K+^+ and p-p-K^- dynamics using the femtoscopy technique

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    International audienceThe interactions of kaons (K) and antikaons (K\mathrm{\overline{K}}) with few nucleons (N) were studied so far using kaonic atom data and measurements of kaon production and interaction yields in nuclei. Some details of the three-body KNN and K\mathrm{\overline{K}}NN dynamics are still not well understood, mainly due to the overlap with multi-nucleon interactions in nuclei. An alternative method to probe the dynamics of three-body systems with kaons is to study the final state interaction within triplet of particles emitted in pp collisions at the Large Hadron Collider, which are free from effects due to the presence of bound nucleons. This Letter reports the first femtoscopic study of p-p-K+^+ and p-p-K^- correlations measured in high-multiplicity pp collisions at s\sqrt{s} = 13 TeV by the ALICE Collaboration. The analysis shows that the measured p-p-K+^+ and p-p-K^- correlation functions can be interpreted in terms of pairwise interactions in the triplets, indicating that the dynamics of such systems is dominated by the two-body interactions without significant contributions from three-body effects or bound states

    Study of flavor dependence of the baryon-to-meson ratio in proton-proton collisions at s\sqrt{s} = 13 TeV

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    The production cross sections of D0 and Λc+ hadrons originating from beauty-hadron decays (i.e., nonprompt) were measured for the first time at midrapidity (|y|<0.5) by the ALICE Collaboration in proton-proton collisions at a center-of-mass energy s=13 TeV. They are described within uncertainties by perturbative QCD calculations employing the fragmentation fractions of beauty quarks to baryons measured at forward rapidity by the LHCb Collaboration. The bb¯ production cross section per unit of rapidity at midrapidity, estimated from these measurements, is dσbb¯/dy||y|<0.5=83.1±3.5(stat)±5.4(syst)-3.2+12.3(extrap) μb. The baryon-to-meson ratios are computed to investigate the hadronization mechanism of beauty quarks. The nonprompt Λc+/D0 production ratio has a similar trend to the one measured for the promptly produced charmed particles and to the p/π+ and Λ/KS0 ratios, suggesting a similar baryon-formation mechanism among light, strange, charm, and beauty hadrons. The pT -integrated nonprompt Λc+/D0 ratio is found to be significantly higher than the one measured in e+e- collisions

    Higher-order correlations between different moments of two flow amplitudes in Pb-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

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    The correlations between different moments of two flow amplitudes, extracted with the recently developed asymmetric cumulants, are measured in Pb-Pb collisions at sNN=5.02TeV recorded by the ALICE detector at the CERN Large Hadron Collider. The magnitudes of the measured observables show a dependence on the different moments as well as on the collision centrality, indicating the presence of nonlinear response in all even moments up to the eighth. Furthermore, the higher-order asymmetric cumulants show different signatures than the symmetric and lower-order asymmetric cumulants. Comparisons with state-of-the-art event generators using two different parametrizations obtained from Bayesian optimization show differences between data and simulations in many of the studied observables, indicating a need for further tuning of the models behind those event generators. These results provide new and independent constraints on the initial conditions and transport properties of the system created in heavy-ion collisions

    Measurement of inclusive J/ψ pair production cross section in pp collisions at s\sqrt{s} =13 TeV

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    The production cross section of inclusive J/ψ pairs in pp collisions at a center-of-mass energy s=13 TeV is measured with ALICE. The measurement is performed for J/ψ in the rapidity interval 2.50. The production cross section of inclusive J/ψ pairs is reported to be 10.3±2.3(stat.)±1.3(syst.) nb in this kinematic interval. The contribution from nonprompt J/ψ (i.e., originated from beauty-hadron decays) to the inclusive sample is evaluated. The effective double-parton scattering cross section is computed, neglecting the single-parton scattering contribution

    Probing the chiral magnetic wave with charge-dependent flow measurements in Pb-Pb collisions at the LHC

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    The Chiral Magnetic Wave (CMW) phenomenon is essential to provide insights into the strong interaction in QCD, the properties of the quark-gluon plasma, and the topological characteristics of the early universe, offering a deeper understanding of fundamental physics in high-energy collisions. Measurements of the charge-dependent anisotropic flow coefficients are studied in Pb-Pb collisions at center-of-mass energy per nucleon-nucleon collision sNN \sqrt{s_{\textrm{NN}}} = 5.02 TeV to probe the CMW. In particular, the slope of the normalized difference in elliptic (v2_{2}) and triangular (v3_{3}) flow coefficients of positively and negatively charged particles as a function of their event-wise normalized number difference, is reported for inclusive and identified particles. The slope r3Norm {r}_3^{\textrm{Norm}} is found to be larger than zero and to have a magnitude similar to r2Norm {r}_2^{\textrm{Norm}} , thus pointing to a large background contribution for these measurements. Furthermore, r2Norm {r}_2^{\textrm{Norm}} can be described by a blast wave model calculation that incorporates local charge conservation. In addition, using the event shape engineering technique yields a fraction of CMW (fCMW_{CMW}) contribution to this measurement which is compatible with zero. This measurement provides the very first upper limit for fCMW_{CMW}, and in the 10–60% centrality interval it is found to be 26% (38%) at 95% (99.7%) confidence level
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