Montesinos, V., Ikeno, N., Oset, E., Albaladejo, M., Nieves, J., & Tolos, L. (2025). On the determination of the D meson width in the nuclear medium with the transparency ratio. Phys. Lett. B, 860, 139172–6pp.
Abstract: We have studied the feasibility of the experimental determination of the width of a D meson in a nuclear medium by using the method of the nuclear transparency. The cross section for inclusive production of a D+ in different nuclei is evaluated, taking care of the D+ absorption in the nucleus, or equivalently, the survival probability of the D+ in its way out of the nucleus from the point of production. We use present values of the in medium width of D mesons and calculate ratios of the cross sections for different nuclei to the 12 C nucleus as reference. We find ratios of the order of 0.6 for heavy nuclei, a large deviation from unity, which indicates that the method proposed is adequate to measure this relevant magnitude, so far only known theoretically.
|
ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2024). Measurement of the Z boson invisible width at √s=13 TeV with the ATLAS detector. Phys. Lett. B, 854, 138705–25pp.
Abstract: A measurement of the invisible width of the boson using events with jets and missing transverse momentum is presented using 37 fb(-1) of 13 TeV proton-proton data collected by the ATLAS detector in 2015 and 2016. The ratio of Z -> inv to Z -> ll events, where inv refers to non-detected particles and l is either an electron or a muon, is measured and corrected for detector effects. Events with at least one energetic central jet with p(T) >= 110 GeV are selected for both the Z -> inv and Z -> ll final states to obtain a similar phase space in the ratio. The invisible width is measured to be 506 +/- 2 (stat.) +/- 12 (syst.) MeV and is the single most precise recoil-based measurement. The result is in agreement with the most precise determination from LEP and the Standard Model prediction based on three neutrino generations.
|
Ge, Z. et al, & Ayet, S. (2024). High-precision measurements of the atomic mass and electron-capture decay Q value of 95 Tc. Phys. Lett. B, 859, 139094–9pp.
Abstract: A direct measurement of the ground-state-to-ground-state electron-capture decay Q value of 95 Tc has been performed utilizing the double Penning trap mass spectrometer JYFLTRAP. The Q value was determined to be 1695.92(13) keV by taking advantage of the high resolving power of the phase-imaging ion-cyclotron-resonance technique to resolve the low-lying isomeric state of 95 Tc (excitation energy of 38.910(40) keV) from the ground state. The mass excess of 95 Tc was measured to be -86015.95(18) keV/c2, exhibiting a precision of about 28 times higher and in agreement with the value from the newest Atomic Mass Evaluation (AME2020). Combined with the nuclear energy-level data for the decay-daughter 95 Mo, two potential ultra-low Q-value transitions are identified for future long-term neutrino-mass determination experiments. The atomic self-consistent many-electron Dirac- Hartree-Fock-Slater method and the nuclear shell model have been used to predict the partial half-lives and energy-release distributions for the two transitions. The dominant correction terms related to those processes are considered, including the exchange and overlap corrections, and the shake-up and shake-off effects. The normalized distribution of the released energy in the electron-capture decay of 95 Tc to excited states of 95 Mo is compared to that of 163 Ho currently being used for electron-neutrino-mass determination.
|
Aguilar, A. C., De Soto, F., Ferreira, M. N., Papavassiliou, J., Pinto-Gomez, F., Rodríguez-Quintero, J., et al. (2024). Nonperturbative four-gluon vertex in soft kinematics. Phys. Lett. B, 858, 139065–7pp.
Abstract: We present a nonperturbative study of the form factor associated with the projection of the full four-gluon vertex on its classical tensor, for a set of kinematics with one vanishing and three arbitrary external momenta. The treatment is based on the Schwinger-Dyson equation governing this vertex, and a large-volume lattice simulation, involving ten thousand gauge field configurations. The key hypothesis employed in both approaches is the “planar degeneracy”, which classifies diverse configurations by means of a single variable, thus enabling their meaningful “averaging”. The results of both approaches show notable agreement, revealing a considerable suppression of the averaged form factor in the infrared. The deviations from the exact planar degeneracy are discussed in detail, and a supplementary variable is used to achieve a more accurate description. The effective charge defined through this special form factor is computed within both approaches, and the results obtained are in excellent agreement.
|
Aguilar, A. C., Brito, N., Ferreira, M. N., Papavassiliou, J., Oliveira, O., & Silva, P. J. (2024). Lattice determination of the Batalin-Vilkovisky function and the strong running interaction. Phys. Lett. B, 858, 139054–8pp.
Abstract: The Batalin-Vilkovisky function is a central component in the modern formulation of the background field method and the physical applications derived from it. In the present work we report on novel lattice results for this particular quantity, obtained by capitalizing on its equality with the Kugo-Ojima function in the Landau gauge. The results of the lattice simulation are in very good agreement with the predictions derived from a continuum analysis based on the corresponding Schwinger-Dyson equations. In addition, we show that an important relation connecting this function with the ghost propagator is fulfilled rather accurately. With the aid of these results, we carry out the first completely lattice-based determination of the process-independent strong running interaction, employed in a variety of phenomenological studies.
|
