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n_TOF Collaboration(Lederer-Woods, C. et al.), Domingo-Pardo, C., & Tain, J. L. (2021). Destruction of the cosmic gamma-ray emitter Al-26 in massive stars: Study of the key Al-26(n, alpha) reaction. Phys. Rev. C, 104(3), L032803–6pp.
Abstract: Neutron destruction reactions of the cosmic gamma-ray emitter Al-26 are of importance to determine the amount of Al-26 ejected into our galaxy by supernova explosions and for Al-26 production in asymptotic giant branch stars. We performed a new measurement of the Al-26(n, alpha) reaction up to 160-keV neutron energy at the neutron time-of-flight facilities n_TOF at CERN and GELINA at EC-JRC. We provide strengths for ten resonances, six of them for the first time. We use our data to calculate astrophysical reactivities for stellar temperatures up to 0.7 GK. Our results resolve a discrepancy between the two previous direct measurements of this reaction, and indicate higher stellar destruction rates than the most recently recommended reactivity.
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Candia, P., Cottin, G., Mendez, A., & Muñoz, V. (2021). Searching for light long lived neutralinos at Super-Kamiokande. Phys. Rev. D, 104(5), 055024–11pp.
Abstract: Light neutralinos could be copiously produced from the decays of mesons generated in cosmic-ray air showers. These neutralinos can be long-lived particles in the context of R-parity violating (RPV) supersymmetric models, implying that they could be capable of reaching the surface of the earth and decay within the instrumental volume of large neutrino detectors. In this article, we use atmospheric neutrino data from the Super-Kamiokande experiment to derive novel constraints for the RPV couplings involved in the production of long-lived light neutralinos from the decays of charged D-mesons and kaons. Our results highlight the potential of neutrino detectors to search for long-lived particles, by demonstrating that it is possible to explore regions of parameter space that are not yet constrained by any fixed-target nor collider experiments.
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Aguilar, A. C., Ambrosio, C. O., De Soto, F., Ferreira, M. N., Oliveira, B. M., Papavassiliou, J., et al. (2021). Ghost dynamics in the soft gluon limit. Phys. Rev. D, 104(5), 054028–18pp.
Abstract: We present a detailed study of the dynamics associated with the ghost sector of quenched QCD in the Landau gauge, where the relevant dynamical equations are supplemented with key inputs originating from large-volume lattice simulations. In particular, we solve the coupled system of Schwinger-Dyson equations that governs the evolution of the ghost dressing function and the ghost-gluon vertex, using as input for the gluon propagator lattice data that have been cured from volume and discretization artifacts. In addition, we explore the soft gluon limit of the same system, employing recent lattice data for the three-gluon vertex that enters in one of the diagrams defining the Schwinger-Dyson equation of the ghost-gluon vertex. The results obtained from the numerical treatment of these equations are in excellent agreement with lattice data for the ghost dressing function, once the latter have undergone the appropriate scale-setting and artifact elimination refinements. Moreover, the coincidence observed between the ghost-gluon vertex in general kinematics and in the soft gluon limit reveals an outstanding consistency of physical concepts and computational schemes.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2021). Light meson spectroscopy from Dalitz plot analyses of eta(c) decays to eta ' K+K-, eta 'pi(+)pi(-), and eta pi(+)pi(-) produced in two-photon interactions. Phys. Rev. D, 104(7), 072002–23pp.
Abstract: We study the processes gamma gamma -> eta(c )-> eta'K+K-, eta'pi(+)pi(-), and eta pi(+)pi(-) using a data sample of 519 fb(-1) recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e(+)e(-) collider at center-of-mass energies at and near the Upsilon(nS) (n = 2, 3, 4) resonances. This is the first observation of the decay eta(c)-> eta'K+K- and we measure the branching fraction Gamma (eta(c) -> eta' K+K- )/(Gamma(eta(c) -> eta'pi(+)pi(-)) = 0.644 +/- 0.039(stat) +/- 0.032(sys). Significant interference is observed between gamma gamma ->eta(c)->eta pi(+)pi(-) and the nonresonant two-photon process gamma gamma -> eta pi(+)pi(-). A Dalitz plot analysis is performed of eta(c) decays to eta'K+K-, eta'pi(+)pi(-) and eta pi(+)pi(-). Combined with our previous analysis of eta(c) -> K (K) over bar pi, we measure the K-0*(1430) parameters and the ratio between its eta'K and pi K couplings. The decay eta(c) -> eta'pi(+)pi(-) is dominated by the f(0)(2100) resonance, also observed in J/psi radiative decays. A new a(0) (1700) -> eta pi resonance is observed in the eta(c) -> eta pi(+)pi(-) channel. We also compare eta(c) decays to eta and eta' final states in association with scalar mesons as they relate to the identification of the scalar glueball.
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Kuhn, K. et al, & Nacher, E. (2021). Experimental study of the nature of the 1(-) and 2(-) excited excited states in Be-10 using the Be-11(p, d) reaction in inverse kinematics. Phys. Rev. C, 104(4), 044601–10pp.
Abstract: The nature of the 1(-) and 2(-) excited states in Be-10 is studied using the Be-11(p, d) transfer reaction in inverse kinematics at 10A MeV at TRIUMF ISAC-II, in particular to assess whether either of them can be considered as an excited halo state. The angular distributions for both states are extracted using deuteron-gamma( )coincidences and analyzed using a transfer model taking into account one-step and two-step processes. A good fit of the angular distributions is obtained considering only the one-step process, whereby an inner p(3/2) neutron of Be-11 is removed, leaving the halo neutron intact. Higher-order processes however cannot be rejected. The small spectroscopic factors extracted suggest that the structure of both states is not uniquely halo-like, but rather display a more complex configuration mixing cluster and halo structures. Further insights are limited, as this experiment specifically probed the halo-like (but not cluster-like) Be-11 (1/2(+)) circle times (nu p(3/2))(-1) configuration in both states.
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