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At least 73 records · Page 4

Study of electromagnetic Dalitz decays χ c J → μ + μ - J / ψ

Using 4.48 × 10 8 ψ (3686) events collected with the BESIII detector, we search for the decays χ cJ → μ + μ – J/ψ through the radiative decays ψ(3686) → γχ cJ , where J = 0,1,2. The decays χ c1,2 → μ + μ – J/ψ are observed, and the corresponding branching fractions are measured to be B(χ c1 → μ + μ – J/ψ) = (2.51 ± 0.18 ± 0.20) × 10 –4 and B(χ c2 → μ + μ – J/ψ) = (2.33 ± 0.18 ± 0.29) × 10 –4 , where the first uncertainty is statistical and the second one systematic. No significant χ c0 → μ + μ – J/ψ decay is observed, and the upper limit on the branching fraction is determined to be 2.0×10 –5 at 90% confidence level. Furthermore, we present a study of dimuon invariant mass dependent transition form factor for the decays χ c1,2 → μ + μ – J/ψ.

astronomy & astrophysics↗

Manipulating strong electromagnetic fields with the average transverse momentum of relativistic nuclear collisions

Abstract We show that an event-shape engineering based on the mean transverse momentum of charged hadrons, $$[p_t]$$ [ p t ] , provides an optimal handle on the strength of the magnetic field created in central heavy-ion collisions at high energy. This is established through quantitative evaluations of the correlation existing between the event-by-event magnetic field produced by the spectator protons in 5.02 TeV Pb + Pb collisions and the event-by-event $$[p_t]$$ [ p t ] at a given collision centrality. We argue that the event selection based on $$[p_t]$$ [ p t ] provides a better handle on the magnetic field than the more traditional selection based on the event ellipticities. Advantages brought by this new method for the experimental search of the chiral magnetic effect are discussed.

Giacalone, Giuliano (ORCID:0000000287761034)↗

High-Density Signal Interface Electromagnetic Radiation Prediction for Electromagnetic Compatibility Evaluation

Radiated power calculation approaches for practical scenarios of incomplete high- density interface characterization information and incomplete incident power information are presented. The suggested approaches build upon a method that characterizes power losses through the definition of power loss constant matrices. Potential radiated power estimates include using total power loss information, partial radiated power loss information, worst case analysis, and statistical bounding analysis. A method is also proposed to calculate radiated power when incident power information is not fully known for non-periodic signals at the interface. Incident data signals are modeled from a two-state Markov chain where bit state probabilities are derived. The total spectrum for windowed signals is postulated as the superposition of spectra from individual pulses in a data sequence. Statistical bounding methods are proposed as a basis for the radiated power calculation due to the statistical calculation complexity to find a radiated power probability density function.

42 ENGINEERING↗