Temperature measurement of fragment emitting systems in Au+Au 35 MeV/nucleon collisions

We report on the results of experiments performed to investigate the Au1Au 35 MeV/nucleon reaction. The reaction products generated in the disassembly of the unique source formed in central collisions and those coming from the decay of the quasiprojectile in peripheral and midperipheral ones ~five different impact parameters! were identified through a careful data selection based on the study of energy and angular distributions. The excitation energies of the fragment sources have been extracted through a calorimetric method and by means of a comparison with model calculations. The nuclear temperatures of these decaying systems have been measured from the relative isotopic abundances and, also for central collisions, from the relative populations of excited states. The temperatures of the quasiprojectile disassembling systems are slowly increasing going towards smaller impact parameter. The relationship between temperature and excitation energy seems to be almost independent of the characteristics of the emitting source. The extracted caloric curve shows a slow monotonic increase with increasing excitation energy. A comparison with data derived from Au fragmentation at much higher incident energies is discussed. @S0556-2813~98!04408-2

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Updated measurement of decay-time-dependent CP asymmetries in D0→K+K−D^0 \to K^+K^- and D0→π+π−D^0 \to \pi^+\pi^- decays

International audienceA search for decay-time-dependent charge-parity (CP) asymmetry in D0→K+K- and D0→π+π- decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13 TeV, and corresponding to an integrated luminosity of 5.4  fb-1. The D0 mesons are required to originate from semileptonic decays of b hadrons, such that the charge of the muon identifies the flavor of the neutral D meson at production. The asymmetries in the effective decay widths of D0 and D¯0 mesons are determined to be AΓ(K+K-)=(-4.3±3.6±0.5)×10-4 and AΓ(π+π-)=(2.2±7.0±0.8)×10-4, where the uncertainties are statistical and systematic, respectively. The results are consistent with CP symmetry and, when combined with previous LHCb results, yield AΓ(K+K-)=(-4.4±2.3±0.6)×10-4 and AΓ(π+π-)=(2.5±4.3±0.7)×10-4

First measurement of the Z→μ+μ−Z\rightarrow \mu^+ \mu^- angular coefficients in the forward region of pppp collisions at s=13\sqrt{s}=13 TeV

The first study of the angular distribution of $\mu^+ \mu^-$ pairs produced in the forward rapidity region via the Drell-Yan reaction $pp \rightarrow \gamma^{*}/Z +X \rightarrow l^+ l^- + X$ is presented, using data collected with the LHCb detector at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.1 $\rm{fb}^{-1}$. The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the $Z$-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton

Precision measurement of forward ZZ boson production in proton-proton collisions at s=13\sqrt{s} = 13 TeV

A precision measurement of the $Z$ boson production cross-section at $\sqrt{s} = 13$ TeV in the forward region is presented, using $pp$ collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb$^{-1}$. The production cross-section is measured using $Z\rightarrow\mu^+\mu^-$ events within the fiducial region defined as pseudorapidity $2.020$ GeV/$c$ for both muons and dimuon invariant mass $60<M_{\mu\mu}<120$ GeV/$c^2$. The integrated cross-section is determined to be \begin{equation*} \sigma(Z\rightarrow\mu^+\mu^-) = 195.3 \pm 0.2 \pm 1.5 \pm 3.9~pb, \end{equation*} where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions, including a prediction at next-to-next-to-leading order in perturbative quantum chromodynamics and a prediction with resummation

Study of the lineshape of the χc1(3872)\chi_{c1}(3872) state

A study of the lineshape of the $\chi_{c1}(3872)$ state is made using a data sample corresponding to an integrated luminosity of 3 fb$^{-1}$ collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate $\chi_{c1}(3872)$ and $ψ(2S)$ mesons from $b$-hadron decays are selected in the $J/ψπ^+π^-$ decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the $\chi_{c1}(3872)$) and $ψ(2S)$ states, $Δm$, and the width of the $\chi_{c1}(3872)$ state, $Γ_{BW}$, are determined to be $\frac {Δm=185.598±0.067±0.068 \, MeV,} {Γ_{BW}=1.39±0.24±0.10 \, MeV}$, where the first uncertainty is statistical and the second systematic. Using a Flatté-inspired model, the mode and full width at half maximum of the lineshape are determined to be $\frac {mode=3871.69_{-0.04-0.13}^{+0.00+0.05} MeV,} {FWHM=0.22_{-0.06-0.13}^{+0.07+0.11} MeV}$. An investigation of the analytic structure of the Flatté amplitude reveals a pole structure, which is compatible with a quasibound $D^0\bar{D}^{*0}$ state but a quasivirtual state is still allowed at the level of 2 standard deviations