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2.
Phys Rev Lett ; 127(20): 202301, 2021 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-34860039

RESUMO

The prompt production of the charm baryon Λ_{c}^{+} and the Λ_{c}^{+}/D^{0} production ratios were measured at midrapidity with the ALICE detector in pp and p-Pb collisions at sqrt[s_{NN}]=5.02 TeV. These new measurements show a clear decrease of the Λ_{c}^{+}/D^{0} ratio with increasing transverse momentum (p_{T}) in both collision systems in the range 2

3.
Phys Rev Lett ; 127(9): 092302, 2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34506195

RESUMO

The event-by-event correlations between three flow amplitudes are measured for the first time in Pb-Pb collisions, using higher-order symmetric cumulants. We find that different three-harmonic correlations develop during the collective evolution of the medium when compared to correlations that exist in the initial state. These new results cannot be interpreted in terms of previous lower-order flow measurements since contributions from two-harmonic correlations are explicitly removed in the new observables. A comparison to Monte Carlo simulations provides new and independent constraints for the initial conditions and system properties of nuclear matter created in heavy-ion collisions.

4.
Phys Rev Lett ; 127(4): 042302, 2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34355943

RESUMO

A measurement of dielectron production in proton-proton (pp) collisions at sqrt[s]=13 TeV, recorded with the ALICE detector at the CERN LHC, is presented in this Letter. The data set was recorded with a reduced magnetic solenoid field. This enables the investigation of a kinematic domain at low dielectron (ee) invariant mass m_{ee} and pair transverse momentum p_{T,ee} that was previously inaccessible at the LHC. The cross section for dielectron production is studied as a function of m_{ee}, p_{T,ee}, and event multiplicity dN_{ch}/dη. The expected dielectron rate from hadron decays, called hadronic cocktail, utilizes a parametrization of the measured η/π^{0} ratio in pp and proton-nucleus collisions, assuming that this ratio shows no strong dependence on collision energy at low transverse momentum. Comparison of the measured dielectron yield to the hadronic cocktail at 0.15

5.
Phys Rev Lett ; 126(16): 162001, 2021 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-33961482

RESUMO

The elliptic flow of electrons from beauty hadron decays at midrapidity (|y|<0.8) is measured in Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV with the ALICE detector at the LHC. The azimuthal distribution of the particles produced in the collisions can be parametrized with a Fourier expansion, in which the second harmonic coefficient represents the elliptic flow, v_{2}. The v_{2} coefficient of electrons from beauty hadron decays is measured for the first time in the transverse momentum (p_{T}) range 1.3-6 GeV/c in the centrality class 30%-50%. The measurement of electrons from beauty-hadron decays exploits their larger mean proper decay length cτ≈500 µm compared to that of charm hadrons and most of the other background sources. The v_{2} of electrons from beauty hadron decays at midrapidity is found to be positive with a significance of 3.75 σ. The results provide insights into the degree of thermalization of beauty quarks in the medium. A model assuming full thermalization of beauty quarks is strongly disfavored by the measurement at high p_{T}, but is in agreement with the results at low p_{T}. Transport models including substantial interactions of beauty quarks with an expanding strongly interacting medium describe the measurement within uncertainties.

6.
Morphologie ; 105(348): 64-68, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32891508

RESUMO

OBJECTIVE OF THE STUDY: The aim of this study was to assess the anatomical features of the alveolar antral artery (AAA) in edentulous patients using cone beam computed tomography (CBCT). PATIENTS: The sample consisted of 191 CBCT scans of maxillary sinuses (n=382) of male (n=59) and female (n=132) edentulous patients (age: 38-89 years). MATERIAL AND METHODS: The images were analyzed in Dolphin™ 11.9 software. Visualization, location, and diameter of the AAA was registered. RESULTS: AAA was present in 88.5% of the assessed maxillary sinuses. Bilateral visualization was predominant 77% (P<0.0001). The mean vertical distance from the most anterior part of the AAA to the sinus floor was 7.9±6mm in female patients (both sides) and 12±7.22mm on the right side and 10.9±6.86mm on the left side in males. The mean diameter of the AAA was 1.2±0.7mm on both sides in females. In males, the diameter was significantly (P<0.05) larger: 1.5±0.62mm on the right side and 1.4±0.69 on the left side in females. CONCLUSION: The AAA had a higher visualization rate, better visualization, and larger diameter when it was present bilaterally in male and female patients.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Adulto , Idoso , Idoso de 80 Anos ou mais , Artérias , Feminino , Humanos , Masculino , Seio Maxilar , Pessoa de Meia-Idade , Levantamento do Assoalho do Seio Maxilar , Software
7.
Med Oral Patol Oral Cir Bucal ; 26(3): e284-e291, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32856618

RESUMO

BACKGROUND: Pigmented lesions are uncommon in the oral mucosa, and studies investigating the incidence and types of these lesions are desired to improve the diagnostic knowledge of clinicians. The aim of this study was to analyze the distribution of oral pigmented lesions in a Brazilian population. MATERIAL AND METHODS: A retrospective descriptive cross-sectional study was performed. Oral pigmented lesions were retrieved from the files of two oral and maxillofacial pathology services from Brazil over a 45-year period (1974-2019). The clinical data and the diagnoses of each case were retrieved and included in a Microsoft Excel® database. RESULTS: From 77.074 lesions diagnosed in this period, 761 (0.99%) represented pigmented lesions of the oral mucosa, including 351 (46.1%) melanocytic and 410 (53.9%) non-melanocytic lesions, with a higher incidence in females (73.2%) between the fourth and seventh decades of life. Amalgam tattoo (53.6%) represented the most common lesion, followed by melanotic macule (18.3%) and racial pigmentation (10.8%). Other pigmented lesions included nevus (9.9%), post-inflammatory pigmentation (3%), melanoma (2.1%), melanoacanthoma (1.4%), smoker's melanosis (0.4%), drug-induced pigmentation (0.3%), and melanotic neuroectodermal tumor of infancy (0.1%). The buccal mucosa was the most commonly affected site (25.2%), followed by the alveolar ridge (14.5%), and gingiva (11.8%). CONCLUSIONS: The current findings were similar to previous studies with minor differences due methodology and characteristics of the services from where lesions were retrieved. The knowledge of these data may contribute to a better understanding of oral pigmented lesions and assist clinicians to better recognize and manage them.


Assuntos
Doenças da Boca , Brasil/epidemiologia , Estudos Transversais , Diagnóstico Diferencial , Feminino , Humanos , Doenças da Boca/diagnóstico , Doenças da Boca/epidemiologia , Mucosa Bucal , Estudos Retrospectivos
8.
Med Oral Patol Oral Cir Bucal ; 26(3): e379-e386, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33340079

RESUMO

BACKGROUND: Melanoma is an aggressive malignant tumor, rarely observed in the oral cavity. The aim of this study was to describe the clinicopathologic features of a series of oral melanomas. MATERIAL AND METHODS: A retrospective descriptive study was performed. A total of 15,482 biopsy records from two oral and maxillofacial pathology services in Brazil were analyzed. All cases of oral melanomas were reviewed, and clinical, demographic, histopathological data, treatment, and follow-up status were collected. In addition, immunohistochemistry stains (pan-cytokeratin AE1/AE3, vimentin, α-SMA, CD45, S-100 protein, HMB-45, Melan A, and Ki-67) were performed. RESULTS: The series comprised of 5 males (71.4%) and 2 females (28.6%), with a mean age of 58.0 ± 9.2 years (range: 45-69 years) and a 2.5:1 male-to-female ratio. The gingiva (n = 3, 42.8%) and hard palate (n = 2, 28.6%) were the most common affected sites, presenting clinically as ulcerated swellings with a brown to black color. Cervical lymph node metastasis was detected in three patients during the first examination. Microscopically, 6 cases (85.7%) were melanotic, and one (14.3%) was amelanotic. Most cases (n = 4, 57.1%) presented a predominance of epithelioid cells. S-100 and HMB-45 were positive in all cases (n = 7, 100.0%). In contrast, only 4 cases (57.1%) were positive for Melan-A. The proliferative index with Ki-67 was high, with labeling index ranging from 70.0% to more than 90% of positive cells. Five patients died from complications of the tumors after a mean follow-up period of 7.8 months. CONCLUSIONS: Melanoma is an aggressive malignant tumor that rarely occurs in the oral cavity. It occurs mainly in adult and elderly patients and often is diagnosed in advanced stages. The current findings were similar to previous studies and reflected the characteristics of the services from where lesions were retrieved.


Assuntos
Melanoma , Neoplasias Bucais , Adulto , Idoso , Brasil/epidemiologia , Feminino , Humanos , Masculino , Melanoma/diagnóstico , Melanoma/epidemiologia , Pessoa de Meia-Idade , Neoplasias Bucais/epidemiologia , Estudos Retrospectivos
9.
Phys Rev Lett ; 125(16): 162001, 2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-33124836

RESUMO

In this Letter, we report the first measurement of the inelastic cross section for antideuteron-nucleus interactions at low particle momenta, covering a range of 0.3≤p<4 GeV/c. The measurement is carried out using p-Pb collisions at a center-of-mass energy per nucleon-nucleon pair of sqrt[s_{NN}]=5.02 TeV, recorded with the ALICE detector at the CERN LHC and utilizing the detector material as an absorber for antideuterons and antiprotons. The extracted raw primary antiparticle-to-particle ratios are compared to the results from detailed ALICE simulations based on the geant4 toolkit for the propagation of (anti)particles through the detector material. The analysis of the raw primary (anti)proton spectra serves as a benchmark for this study, since their hadronic interaction cross sections are well constrained experimentally. The first measurement of the inelastic cross section for antideuteron-nucleus interactions averaged over the ALICE detector material with atomic mass numbers ⟨A⟩=17.4 and 31.8 is obtained. The measured inelastic cross section points to a possible excess with respect to the Glauber model parametrization used in geant4 in the lowest momentum interval of 0.3≤p<0.47 GeV/c up to a factor 2.1. This result is relevant for the understanding of antimatter propagation and the contributions to antinuclei production from cosmic ray interactions within the interstellar medium. In addition, the momentum range covered by this measurement is of particular importance to evaluate signal predictions for indirect dark-matter searches.

10.
Arq. bras. med. vet. zootec. (Online) ; 72(4): 1113-1121, July-Aug. 2020. tab, ilus
Artigo em Inglês | LILACS, VETINDEX | ID: biblio-1131513

RESUMO

A proximidade dos primatas não humanos (PNH) com o ser humano pode ser considerada um fator de risco para transmissão de bactérias entre essas duas populações. Neste estudo, foi investigada a microbiota anfibiôntica aeróbica oral e retal de calitriquídeos em um fragmento de Mata Atlântica localizado no Rio de Janeiro, Brasil, e foram realizados testes fenotípicos para detecção de bactérias multirresistentes nos isolados encontrados. Foram capturados 14 calitriquídeos e coletadas 21 amostras (14 de cavidade oral e sete de cavidade retal) em dois pontos da mata próximos às habitações humanas. As espécies mais frequentes, na cavidade oral, foram Klebsiella oxytoca (50,0%), K. pneumoniae (28,6%), Kluyvera ascorbata (21,4%) e Stenotrophomonas maltophilia (21,4%) e, na cavidade retal, K. pneumoniae (85,7%), Escherichia coli (28,6%) e Enterobacter spp. (42,9%). Todos os 48 isolados da família Enterobacteriaceae foram negativos para ESBL (betalactamase de espectro ampliado), mostrando-se não produtores da enzima nos dois métodos utilizados: disco-aproximação e método de detecção automatizado. Na pesquisa de ERC (enterobactérias resistentes a carbapenêmicos), esses mesmos isolados não apresentaram resistência aos antibióticos imipenem, meropenem e ertapenem. Todas as bactérias isoladas apresentam um potencial zoonótico, o que representa um risco à saúde pública e à conservação das espécies.(AU)


Proximity of nonhuman primates (NHP) to humans can be considered a risk factor for transmission of pathogens between these two populations. This study investigated the oral and rectal aerobic bacterial microbiota of marmosets in an anthropized area of the Atlantic Forest located in Rio de Janeiro, Brazil, and performed phenotypic tests for detection of multidrug-resistant bacteria. Twenty-one samples (14 from the oral cavity and seven from the rectum) were collected from 14 Callithrix sp. captured in two sites of the forest near human dwellings. The most frequent species identified from the oral cavity swabs were Klebsiella oxytoca (50.0%), K. pneumoniae (28.6%), Kluyvera ascorbata (21.4%) and Stenotrophomonas maltophilia (21.4%), whereas the species most commonly identified from the rectum swabs were K. pneumoniae (85.7%), Enterobacter spp. (42.9%) and Escherichia coli (28.6%). All isolates of family Enterobacteriaceae showed no extended spectrum ß-lactamase production by disk-diffusion and automated detection tests. In the search for carbapenem-resistant enterobacteriaceae these isolates presented no resistance to the imipenem, meropenem and ertapenem antibiotics. The isolate of Staphylococcus aureus was susceptible to oxacillin and the isolate of Enterococcus was susceptible to vancomycin. All isolated bacteria showed zoonotic potential, thus posing a risk to species conservation and public health.(AU)


Assuntos
Humanos , Animais , Reto/microbiologia , Callithrix/microbiologia , Microbiota , Boca/microbiologia , Staphylococcus aureus , Brasil , Transmissão de Doença Infecciosa , Stenotrophomonas maltophilia , Risco à Saúde Humana , Klebsiella oxytoca , Escherichia coli
11.
Phys Rev Lett ; 125(1): 012301, 2020 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-32678650

RESUMO

The first evidence of spin alignment of vector mesons (K^{*0} and ϕ) in heavy-ion collisions at the Large Hadron Collider (LHC) is reported. The spin density matrix element ρ_{00} is measured at midrapidity (|y|<0.5) in Pb-Pb collisions at a center-of-mass energy (sqrt[s_{NN}]) of 2.76 TeV with the ALICE detector. ρ_{00} values are found to be less than 1/3 (1/3 implies no spin alignment) at low transverse momentum (p_{T}<2 GeV/c) for K^{*0} and ϕ at a level of 3σ and 2σ, respectively. No significant spin alignment is observed for the K_{S}^{0} meson (spin=0) in Pb-Pb collisions and for the vector mesons in pp collisions. The measured spin alignment is unexpectedly large but qualitatively consistent with the expectation from models which attribute it to a polarization of quarks in the presence of angular momentum in heavy-ion collisions and a subsequent hadronization by the process of recombination.

12.
Phys Rev Lett ; 125(2): 022301, 2020 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-32701333

RESUMO

The first measurement at the LHC of charge-dependent directed flow (v_{1}) relative to the spectator plane is presented for Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV. Results are reported for charged hadrons and D^{0} mesons for the transverse momentum intervals p_{T}>0.2 GeV/c and 3

13.
Biochem Genet ; 58(4): 580-594, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32277314

RESUMO

The impaired bioavailability of endogenous nitric oxide (NO) in sickle cell anemia (SCA) may be influenced by polymorphisms in the endothelial nitric oxide synthase gene (eNOS). We compared allelic/genotypic frequencies of the eNOS polymorphisms T-786C, VNTR4a/b and G894T between 89 adult SCA patients and 100 healthy controls, and investigated the relationship between these SNPs and markers of hemolysis [lactate dehydrogenase (LDH), indirect bilirubin (IB) and reticulocyte counts], inflammation [interleukins IL-1ß, IL-6, IL-8, Tumor Necrosis Factor (TNF-α) and C-reactive protein (CRP)] and endothelial dysfunction (ED) [soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), soluble L-selectin (sL-selectin), von Willebrand Factor (vWF) antigen and D-dimers] in the patients. The frequencies of the mutant -786C allele and -786C/C genotype were significantly higher in patients (p = 0.02 and p = 0.04, respectively) but not significantly correlated with the markers. For VNTR4a/b and G894T, the allelic/genotypic frequencies did not statistically differ between patient and control groups. Patients carrying the 4a allele and those with the 894G/G genotype showed a significant decrease in IB (p = 0.02 and p = 0.04, respectively), and only patients with the 4a allele exhibited reduced IL-1ß (p = 0.01). The correlation profiles between markers of inflammation and ED significantly differed between patients carrying the mutant alleles and those with wild-type genotypes. This appears to be the first report on the relationship between eNOS gene polymorphisms and markers of hemolysis, inflammation and ED in Brazilian SCA patients. Our results indicate that the SNPs analyzed may influence the phenotypic variability of these patients.


Assuntos
Anemia Falciforme/enzimologia , Anemia Falciforme/genética , Produtos de Degradação da Fibrina e do Fibrinogênio/análise , Hemólise , Molécula 1 de Adesão Intercelular/sangue , Óxido Nítrico Sintase Tipo III/genética , Polimorfismo de Nucleotídeo Único , Molécula 1 de Adesão de Célula Vascular/sangue , Fator de von Willebrand/análise , Adulto , Alelos , Anemia Falciforme/sangue , Anemia Falciforme/epidemiologia , Bilirrubina/sangue , Biomarcadores/sangue , Brasil/epidemiologia , Estudos de Casos e Controles , Citocinas/sangue , Feminino , Frequência do Gene , Haplótipos , Humanos , Inflamação/sangue , L-Lactato Desidrogenase/sangue , Masculino , Contagem de Reticulócitos , Adulto Jovem
14.
Int Endod J ; 53(7): 998-1006, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32239513

RESUMO

AIM: To evaluate the shaping ability of the single-file XP-endo Shaper system (XP-S; FKG Dentaire, La Chaux-de-Fonds, Switzerland) employing a different working time and of the multiple-file ProTaper Next system (Dentsply Sirona, Ballaigues, Switzerland) using micro-computed tomography (micro-CT) technology. METHODOLOGY: Twenty long oval-shaped canals in mandibular incisors were matched anatomically and scanned by micro-CT (Skyscan 1172; Bruker micro-CT, Kontich, Belgium). The canals were divided into two groups (n = 10) according to the canal preparation protocol: XP-endo Shaper (XP-S) with an extra 45 s of instrumentation and ProTaper Next (PTN X4). The images recorded before and after preparation were evaluated for morphometric measures of volume, surface area, structure model index and untouched walls. The data were compared statistically (Student's t-test for homogenous variances and Mann-Whitney test) between the two groups (XP-S and PTN X4) at α = 5%. RESULTS: Root canal preparation significantly increased all parameters (volume, surface area, structure model index and untouched walls) tested in each group (P < 0.05). There was no significant difference (P > 0.05) in the percentage increase of volume (107.50%-93.13%), surface area (27.74%-29.68%) or untouched canal wall (13.08%-11.74%) between XP-S and PTN X4, respectively. CONCLUSIONS: The XP-endo Shaper system (single-file) with an extra 45 s of instrumentation and the ProTaper Next system (multiple files) had a similar root canal shaping ability. Neither technique was able to fully prepare the long oval-shaped canals of mandibular incisors.


Assuntos
Cavidade Pulpar , Preparo de Canal Radicular , Bélgica , Desenho de Equipamento , Humanos , Microtomografia por Raio-X
15.
Arq. bras. med. vet. zootec. (Online) ; 72(2): 443-451, Mar./Apr. 2020. ilus, tab
Artigo em Português | LILACS, VETINDEX | ID: biblio-1128368

RESUMO

O objetivo foi avaliar protocolos de maturação in vitro (MIV) para oócitos de cutias, seguida de fertilização in vitro (FIV) e ativação partenogenética (AP). Os oócitos imaturos (CCOs) foram obtidos por fatiamento do ovário, após OSH, e submetidos a três grupos: MAT - 16 (16 horas de maturação), MAT - 20 (20 horas de maturação) e MAT - 24 (24 horas de maturação), em incubadora de cultivo a 38,8°C, com atmosfera de 5% de CO2 e 95% de umidade relativa. A maturação foi analisada pela presença do primeiro corpúsculo polar. Em seguida, os CCOs maduros foram submetidos à FIV, com período de coincubação dos CCOs e dos espermatozoides de 15h, a 38,8ºC e 5% de CO2, e AP com ionomicina. Os grupos de MIV foram analisados utilizando-se o teste qui-quadrado e, nos experimentos de FIV e AP, foram analisadas a taxa de clivagem e a proporção de desenvolvimento embrionário. A análise estatística foi realizada utilizando-se o programa SAS. Houve diferença significativa entre os grupos de maturação, tendo os grupos MAT - 20 e MAT - 24 apresentado maior porcentagem de oócitos maturados in vitro. As taxas de clivagem e de desenvolvimento embrionário foram de 8,6% e 2,9%, respectivamente, na FIV, e de 63,6% e 15,1%, na AP. Entretanto, nos dois casos, o embrião não passou do estágio de mórula.(AU)


The objective was to evaluate IVM protocols for agouti oocytes, followed by in vitro fertilization (IVF) and parthenogenetic activation (PA). The immature oocytes (CCOs) were obtained by slicing the ovary after OSH and submitted to three groups: MAT - 16 (16 hours maturation), MAT - 20 (20 hours maturation) and MAT - (24 hours maturation), in a culture incubator at 38.8°C, with an atmosphere of 5% CO2 and 95% relative humidity. The maturation was analyzed by the presence of the first polar corpuscle. Then, mature CCOs were submitted to IVF, with co-incubation period of CCOs and spermatozoa from 15h to 38.8°C and 5% of CO2, and PA with inomycin. The IVM groups were analyzed using the chi-square test and in the FIV and PA experiment the rate of cleavage and the rate of embryonic development were analyzed. Statistical analysis was performed using the SAS program. There was a significant difference between the maturation groups, and the MAT - 20 and MAT - 24 groups showed a higher percentage of matured oocytes in vitro. The rates of cleavage and embryonic development were 8.6% and 2.9%, respectively in FIV and 63.6% and 15.1% in PA. However, in both cases the embryo did not pass beyond the morula stage.(AU)


Assuntos
Animais , Oócitos , Fertilização In Vitro/veterinária , Técnicas de Maturação in Vitro de Oócitos/veterinária , Dasyproctidae , Partenogênese , Ionomicina
16.
Phys Rev Lett ; 124(9): 092301, 2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-32202883

RESUMO

The study of the strength and behavior of the antikaon-nucleon (K[over ¯]N) interaction constitutes one of the key focuses of the strangeness sector in low-energy quantum chromodynamics (QCD). In this Letter a unique high-precision measurement of the strong interaction between kaons and protons, close and above the kinematic threshold, is presented. The femtoscopic measurements of the correlation function at low pair-frame relative momentum of (K^{+}p⊕K^{-}p[over ¯]) and (K^{-}p⊕K^{+}p[over ¯]) pairs measured in pp collisions at sqrt[s]=5, 7, and 13 TeV are reported. A structure observed around a relative momentum of 58 MeV/c in the measured correlation function of (K^{-}p⊕K^{+}p[over ¯]) with a significance of 4.4σ constitutes the first experimental evidence for the opening of the (K[over ¯]^{0}n⊕K^{0}n[over ¯]) isospin breaking channel due to the mass difference between charged and neutral kaons. The measured correlation functions have been compared to Jülich and Kyoto models in addition to the Coulomb potential. The high-precision data at low relative momenta presented in this work prove femtoscopy to be a powerful complementary tool to scattering experiments and provide new constraints above the K[over ¯]N threshold for low-energy QCD chiral models.

19.
Phys Rev Lett ; 123(14): 142301, 2019 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-31702212

RESUMO

Measurements of anisotropic flow coefficients (v_{n}) and their cross-correlations using two- and multiparticle cumulant methods are reported in collisions of pp at sqrt[s]=13 TeV, p-Pb at a center-of-mass energy per nucleon pair sqrt[s_{NN}]=5.02 TeV, Xe-Xe at sqrt[s_{NN}]=5.44 TeV, and Pb-Pb at sqrt[s_{NN}]=5.02 TeV recorded with the ALICE detector. The multiplicity dependence of v_{n} is studied in a very wide range from 20 to 3000 particles produced in the midrapidity region |η|<0.8 for the transverse momentum range 0.2v_{3}>v_{4} is found in pp and p-Pb collisions, similar to that seen in large collision systems, while a weak v_{2} multiplicity dependence is observed relative to nucleus-nucleus collisions in the same multiplicity range. Using a novel subevent method, v_{2} measured with four-particle cumulants is found to be compatible with that from six-particle cumulants in pp and p-Pb collisions. The magnitude of the correlation between v_{n}^{2} and v_{m}^{2}, evaluated with the symmetric cumulants SC(m,n) is observed to be positive at all multiplicities for v_{2} and v_{4}, while for v_{2} and v_{3} it is negative and changes sign for multiplicities below 100, which may indicate a different v_{n} fluctuation pattern in this multiplicity range. The observed long-range multiparticle azimuthal correlations in high multiplicity pp and p-Pb collisions can neither be described by pythia 8 nor by impact-parameter-Glasma, music, and ultrarelativistic quantum molecular dynamics model calculations, and hence, provide new insights into the understanding of collective effects in small collision systems.

20.
Phys Rev Lett ; 123(11): 112002, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31573229

RESUMO

This Letter presents the first experimental observation of the attractive strong interaction between a proton and a multistrange baryon (hyperon) Ξ^{-}. The result is extracted from two-particle correlations of combined p-Ξ^{-}⊕p[over ¯]-Ξ[over ¯]^{+} pairs measured in p-Pb collisions at sqrt[s_{NN}]=5.02 TeV at the LHC with ALICE. The measured correlation function is compared with the prediction obtained assuming only an attractive Coulomb interaction and a standard deviation in the range [3.6, 5.3] is found. Since the measured p-Ξ^{-}⊕p[over ¯]-Ξ[over ¯]^{+} correlation is significantly enhanced with respect to the Coulomb prediction, the presence of an additional, strong, attractive interaction is evident. The data are compatible with recent lattice calculations by the HAL-QCD Collaboration, with a standard deviation in the range [1.8, 3.7]. The lattice potential predicts a shallow repulsive Ξ^{-} interaction within pure neutron matter and this implies stiffer equations of state for neutron-rich matter including hyperons. Implications of the strong interaction for the modeling of neutron stars are discussed.

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