Measurement of jet radial profiles in Pb\u2013Pb collisions at 1asNN = 2.76 TeV

The jet radial structure and particle transverse momentum (pT) composition within jets are presented in centrality-selected Pb\u2013Pb collisions at 1asNN = 2.76 TeV. Track-based jets, which are also called charged jets, were reconstructed with a resolution parameter of R = 0.3 at midrapidity |\u3b7ch jet| < 0.6 for transverse momenta pT, ch jet = 30\u2013120 GeV/c. Jet\u2013hadron correlations in relative azimuth and pseudorapidity space (\u3c6,\u3b7) are measured to study the distribution of the associated particles around the jet axis for different pT,assoc-ranges between 1 and 20 GeV/c. The data in Pb\u2013Pb collisions are compared to reference distributions for pp collisions, obtained using embedded PYTHIA simulations. The number of high-pT associate particles (4 < pT,assoc < 20 GeV/c) in Pb\u2013Pb collisions is found to be suppressed compared to the reference by 30 to 10%, depending on centrality. The radial particle distribution relative to the jet axis shows a moderate modification in Pb\u2013Pb collisions with respect to PYTHIA. High-pT associate particles are slightly more collimated in Pb\u2013Pb collisions compared to the reference, while low-pT associate particles tend to be broadened. The results, which are presented for the first time down to pT, ch jet = 30 GeV/c in Pb\u2013Pb collisions, are compatible with both previous jet\u2013hadron-related measurements from the CMS Collaboration and jet shape measurements from the ALICE Collaboration at higher pT, and add further support for the established picture of in-medium parton energy loss

Study of the \u39b\u2013\u39b interaction with femtoscopy correlations in pp and p\u2013Pb collisions at the LHC

This work presents new constraints on the existence and the binding energy of a possible \u39b\u2013\u39b bound state, the H-dibaryon, derived from \u39b\u2013\u39b femtoscopic measurements by the ALICE collaboration. The results are obtained from a new measurement using the femtoscopy technique in (Figure presented.) collisions at s=13 TeV and p\u2013Pb collisions at sNN=5.02 TeV, combined with previously published results from (Figure presented.) collisions at s=7 TeV. The \u39b\u2013\u39b scattering parameter space, spanned by the inverse scattering length f0 121 and the effective range d0, is constrained by comparing the measured \u39b\u2013\u39b correlation function with calculations obtained within the Lednick\ufd model. The data are compatible with hypernuclei results and lattice computations, both predicting a shallow attractive interaction, and permit to test different theoretical approaches describing the \u39b\u2013\u39b interaction. The region in the (f0 121,d0) plane which would accommodate a \u39b\u2013\u39b bound state is substantially restricted compared to previous studies. The binding energy of the possible \u39b\u2013\u39b bound state is estimated within an effective-range expansion approach and is found to be B\u39b\u39b=3.2 122.4+1.6(stat) 121.0+1.8(syst) MeV

Search for collectivity with azimuthal J/psi-hadron correlations in high multiplicity p-Pb collisions at ,root s(NN)=5.02 and 8.16 TeV

We present a measurement of azimuthal correlations between inclusive J/psi and charged hadrons in p-Pb collisions recorded with the ALICE detector at the CERN LHC. The J/psi are reconstructed at forward (p-going, 2.03 <y <3.53) and backward (Pb-going, -4.46 <y <-2.96) rapidity via their mu(+)mu(-) decay channel, while the charged hadrons are reconstructed at mid-rapidity (vertical bar eta vertical bar <1.8). The correlations are expressed in terms of associated charged-hadron yields per W . trigger. A rapidity gap of at least 1.5 units is required between the trigger J/psi and the associated charged hadrons. Possible correlations due to collective effects are assessed by subtracting the associated per-trigger yields in the low-multiplicity collisions from those in the high-multiplicity collisions. After the subtraction, we observe a strong indication of remaining symmetric structures at Delta phi approximate to 0 and Delta phi approximate to pi), similar to those previously found in two-particle correlations at middle and forward rapidity. The corresponding second-order Fourier coefficient (v(2) ) in the transverse momentum interval between 3 and 6 GeV/c is found to be positive with a significance of about 5 sigma. The obtained results are similar to the J/psi v(2) coefficients measured in Pb-Pb collisions at root s(NN) = 5.02 TeV, suggesting a common mechanism at the origin of the J/psi v(2) . (C) 2018 The Author. Published by Elsevier B.V.Peer reviewe

Measurement of electrons from semileptonic heavy-flavour hadron decays at midrapidity in pp and Pb-Pb collisions at √ s(NN)=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\u201310%), semi-central (30\u201350%) and peripheral (60\u201380%) lead\u2013lead (Pb\u2013Pb) collisions at sNN=5.02 TeV in the pT intervals 0.5\u201326 GeV/c (0\u201310% and 30\u201350%) and 0.5\u201310 GeV/c (60\u201380%). The production cross section in proton\u2013proton (pp) collisions at s=5.02 TeV was measured as well in 0.5<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\u2013nucleon 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

Systematic studies of correlations between different order flow harmonics in Pb-Pb collisions at root s(NN)=2.76 TeV

The correlations between event-by-event fluctuations of anisotropic flow harmonic amplitudes have been measured in Pb-Pb collisions at root s(NN) = 2.76 TeV with the ALICE detector at the Large Hadron Collider. The results are reported in terms of multiparticle correlation observables dubbed symmetric cumulants. These observables are robust against biases originating from nonflow effects. The centrality dependence of correlations between the higher order harmonics (the quadrangular v(4) and pentagonal v(5) flow) and the lower order harmonics (the elliptic v(2) and triangular v(3) flow) is presented. The transverse momentum dependences of correlations between v(3) and v(2) and between v(4) and v(2) are also reported. The results are compared to calculations from viscous hydrodynamics and a multiphase transport (AMPT) model calculations. The comparisons to viscous hydrodynamic models demonstrate that the different order harmonic correlations respond differently to the initial conditions and the temperature dependence of the ratio of shear viscosity to entropy density (eta/s). Asmall average value of eta/s is favored independent of the specific choice of initial conditions in the models. The calculations with the AMPT initial conditions yield results closest to the measurements. Correlations among the magnitudes of v(2), v(3), and v(4) show moderate p(T) dependence in midcentral collisions. This might be an indication of possible viscous corrections to the equilibrium distribution at hadronic freeze-out, which might help to understand the possible contribution of bulk viscosity in the hadronic phase of the system. Together with existing measurements of individual flow harmonics, the presented results provide further constraints on the initial conditions and the transport properties of the system produced in heavy-ion collisions

One-dimensional charged kaon femtoscopy in p-Pb collisions at root s(NN)=5.02 TeV

The correlations of identical charged kaons were measured in p-Pb collisions at 1asNN = 5.02 TeV by the ALICE experiment at the LHC. The femtoscopic invariant radii and correlation strengths were extracted from one-dimensional kaon correlation functions and were compared with those obtained in pp and Pb-Pb collisions at 1as = 7 TeV and 1asNN = 2.76 TeV, respectively. The presented results also complement the identical-pion femtoscopic data published by the ALICE collaboration. The extracted radii increase with increasing charged- particle multiplicity and decrease with increasing pair transverse momentum. At comparable multiplicities, the radii measured in p-Pb collisions are found to be close to those observed in pp collisions. The obtained femtoscopic parameters are reproduced by the EPOS 3 hadronic interaction model and disfavor models with large initial size or strong collective expansion at low multiplicities

Longitudinal and azimuthal evolution of two-particle transverse momentum correlations in Pb-Pb collisions at root √sNN=2.76 TeV

This paper presents the first measurements of the charge independent (CI) and charge dependent (CD) two-particle transverse momentum correlators G2CI and G2CD in Pb–Pb collisions at sNN=2.76TeV by the ALICE collaboration. The two-particle transverse momentum correlator G2 was introduced as a measure of the momentum current transfer between neighboring system cells. The correlators are measured as a function of pair separation in pseudorapidity (Δη) and azimuth (Δφ) and as a function of collision centrality. From peripheral to central collisions, the correlator G2CI exhibits a longitudinal broadening while undergoing a monotonic azimuthal narrowing. By contrast, G2CD exhibits a narrowing along both dimensions. These features are not reproduced by models such as HIJING and AMPT. However, the observed narrowing of the correlators from peripheral to central collisions is expected to result from the stronger transverse flow profiles produced in more central collisions and the longitudinal broadening is predicted to be sensitive to momentum currents and the shear viscosity per unit of entropy density η/s of the matter produced in the collisions. The observed broadening is found to be consistent with the hypothesized lower bound of η/s and is in qualitative agreement with values obtained from anisotropic flow measurements

Two-particle differential transverse momentum and number density correlations in p-Pb collisions at 5.02 TeV and Pb-Pb collisions at 2.76 TeV at the CERN Large Hadron Collider

We present measurements of two-particle differential number correlation functions R2 and transverse momentum correlation functions P2, obtained from p-Pb collisions at 5.02 TeV and Pb-Pb collisions at 2.76 TeV. The results are obtained by using charged particles in the pseudorapidity range |\u3b7|<1.0 and transverse momentum range 0.2<2.0 GeV/c as a function of pair separation in pseudorapidity, |\u394\u3b7|, azimuthal angle \u394\u3c6, and for several charged-particle multiplicity classes. Measurements are carried out for like-sign and unlike-sign charged-particle pairs separately and combined to obtain charge-independent and charge-dependent correlation functions. We study the evolution of the width of the near-side peak of these correlation functions with collision centrality. Additionally, we study Fourier decompositions of the correlators in \u394\u3c6 as a function of pair separation |\u394\u3b7|. Significant differences in the dependence of their harmonic coefficients on multiplicity classes are found. These differences can be exploited, in theoretical models, to obtain further insight into charged-particle production and transport in heavy-ion collisions. Moreover, an upper limit of nonflow contributions to flow coefficients vn measured in Pb-Pb collisions based on the relative strength of Fourier coefficients measured in p-Pb interactions is estimated

The Entorhinal Cortex Atrophy Score Is Diagnostic and Prognostic in Mild Cognitive Impairment.

peer reviewed[en] BACKGROUND: Structural magnetic resonance imaging (MRI) is routinely performed in patients with mild cognitive impairment (MCI), but diagnostic accuracy to detect early cerebral atrophy is limited. OBJECTIVE: To validate the visual entorhinal cortex atrophy (ERICA) rating scale regarding diagnosis, biomarker status, neuropsychological profile, and dementia risk in MCI. METHODS: The ERICA score was retrospectively assessed regarding its discrimination of MCI (n = 80) from subjective cognitive decline and Alzheimer's disease (AD) dementia (n = 60, respectively), its prediction of conversion to dementia (median follow-up 28 months) and amyloid/tau biomarker status, and its association with neuropsychological tests. RESULTS: The ERICA score achieved 97% positive predictive value (PPV) for the presence of MCI. Discrimination between MCI and AD dementia (area under the curve: 0.71) was comparable to volumetry, and superior to the medial temporal lobe atrophy (MTA) score (p = 0.006). The PPV of the ERICA score for conversion to dementia was 83%, equivalent to tau status. It achieved 90% PPV for conversion when combined with tau, and 100% negative predictive value with verbal recall. While no measure predicted the predominantly positive amyloid status, the ERICA score was at least comparable to volumetry, and superior to the MTA score in predicting tau positivity (92% PPV for phospho-tau). The ERICA score was associated with verbal learning and memory, and, unlike the MTA score, also with AD-specific deficits in cued verbal recall. CONCLUSION: The ERICA score is a simple and valuable tool to exploit structural MRI for diagnosis and prognosis in MCI and is non-inferior to volumetry

The effects of whole-body electromyostimulation (WB-EMS) in comparison to a multimodal treatment concept in patients with non-specific chronic back pain-A prospective clinical intervention study.

BackgroundAccording to present guidelines, active exercise is one key component in the comprehensive treatment of nonspecific chronic back pain (NSCBP). Whole body electromyostimulation (WB-EMS) is a safe, and time-effective training method, that may be effective in NSCBP-patients.MethodsIn this prospective and controlled nonrandomized clinical study, two therapeutic approaches were compared. One group received 20 minutes WB-EMS per week. An active control group (ACG) received a multimodal therapy program. A third group included subjects without back pain. To all groups, the following measurement instruments were applied: Numeric Rating Scale (NRS), Oswestry Disability Index (ODI), North American Spine Society Instrument (NASS); SF 36 survey and measurements for muscular function and postural stability. In the EMS-group: T0: baseline; T1: at 6 weeks; T2: at 12 weeks and T3: at 24 weeks. In the ACG: T0 baseline and T1 after 4 weeks.ResultsIn the intervention group, 128 patients with low back pain were enrolled, 85 in the WB-EMS group and 43 in the ACG. 34 subjects were allocated to the passive control group. The average age was 58.6 years (18-86 years). In the EMS group, the NRS (1-10) improved statistically and clinically significantly by 2 points. The ODI was reduced by 19.7 points. The NASS and most of the SF 36 items improved significantly. In the multimodal treatment group, only the muscular function improved slightly.ConclusionOur data support the hypothesis that WB-EMS is at least as effective as a multimodal treatment, which is often referred to as being the golden standard. Therefore WB-EMS may be an effective and, with 20 min./week training time, very time-efficient alternative to established multimodal treatment models