NEXT Collaboration(Navarro, K. E. et al), Carcel, S., Carrion, J. V., Lopez, F., Lopez-March, N., Martin-Albo, J., et al. (2023). A compact dication source for Ba2+ tagging and heavy metal ion sensor development. J. Instrum., 18(7), P07044–19pp.
Abstract: We present a tunable metal ion beam that delivers controllable ion currents in the picoamp range for testing of dry-phase ion sensors. Ion beams are formed by sequential atomic evaporation and single or multiple electron impact ionization, followed by acceleration into a sensing region. Controllability of the ionic charge state is achieved through tuning of electrode potentials that influence the retention time in the ionization region. Barium, lead, and cadmium samples have been used to test the system, with ion currents identified and quantified using a quadrupole mass analyzer. Realization of a clean Ba2+ ion beam within a bench-top system represents an important technical advance toward the development and characterization of barium tagging systems for neutrinoless double beta decay searches in xenon gas. This system also provides a testbed for investigation of novel ion sensing methodologies for environmental assay applications, with dication beams of Pb2+ and Cd2+ also demonstrated for this purpose.
|
Feijoo, A., Valcarce Cadenas, V., & Magas, V. K. (2023). The Xi(1620) and Xi(1690) molecular states from S =-2 meson-baryon interaction up to next-to-leading order. Phys. Lett. B, 841, 137927–6pp.
Abstract: We have studied the meson-baryon interaction in the neutral S = -2 sector using an extended Unitarized Chiral Perturbation Theory, which takes into account not only the leading Weinberg-Tomozawa term (as all the previous studies in S = -2 sector), but also the Born terms and next-to-leading order contribution. Based on the SU(3) symmetry of the chiral Lagrangian we took most of the model parameters from the BCN model [1], where these were fitted to a large amount of experimental data in the neutral S = -1 sector. We have shown that our approach is able to generate dynamically both Xi(1620) and Xi(1690) states in very reasonable agreement with the data, and can naturally explain the puzzle with the decay branching ratios of Xi(1690). Our results clearly illustrate the reliability of chiral models implementing unitarization in coupled channels and the importance of considering Born and NLO contributions for precise calculations.
|
ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., Cabrera Urban, S., et al. (2023). Search for pair production of third-generation leptoquarks decaying into a bottom quark and a τ-lepton with the ATLAS detector. Eur. Phys. J. C, 83(11), 1075–35pp.
Abstract: A search for pair-produced scalar or vector leptoquarks decaying into a b-quark and a tau-lepton is presented using the full LHC Run 2 (2015-2018) data sample of 139 fb(-1) collected with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of root s = 13TeV. Events in which at least one tau-lepton decays hadronically are considered, and multivariate discriminants are used to extract the signals. No significant deviations from the Standard Model expectation are observed and 95% confidence-level upper limits on the production cross-section are derived as a function of leptoquark mass and branching ratio B into a tau-lepton and b-quark. For scalar leptoquarks, masses below 1460GeV are excluded assuming B = 100%, while for vector leptoquarks the corresponding limit is 1650GeV (1910GeV) in the minimal-coupling (Yang-Mills) scenario.
|
Câmara, H. B., Joaquim, F. R., & Valle, J. W. F. (2023). Dark-sector seeded solution to the strong CP problem. Phys. Rev. D, 108(9), 095003–6pp.
Abstract: We propose a novel realization of the Nelson-Barr mechanism “seeded” by a dark sector containing scalars and vectorlike quarks. Charge parity (CP) and a Z8 symmetry are spontaneously broken by the complex vacuum expectation value of a singlet scalar, leaving a residual Z2 symmetry that stabilizes dark matter (DM). A complex Cabibbo-Kobayashi-Maskawa matrix arises via one-loop corrections to the quark mass matrix mediated by the dark sector. In contrast with other proposals where nonzero contributions to the strong CP phase arise at the one-loop level, in our case this occurs only at two loops, enhancing naturalness. Our scenario also provides a viable weakly interacting massive particle scalar DM candidate.
|
Abreu, L. M., Dai, L. R., & Oset, E. (2023). J/Psi decay to omega, phi, K*0 plus f0(1370), f0(1710), K0*(1430), f2(1270), f'2 (1525) and K2*(1430): Role of the D-wave for tensor production. Phys. Lett. B, 843, 137999–10pp.
Abstract: We reassess the decay of the J/Psi into an omega, phi, K*0 and one of the f0(1370), f0(1710), f2(1270), f'2 (1525), K0*(1430) and K2*(1430) resonances. We benefit from previous works that considered this reaction as a J/Psi decay into three vector mesons, with a scalar or tensor resonance being formed from the interaction of two of these vectors. The novelty here with respect to former studies is the investigation of the relation between the scalar meson and tensor productions for the first time. To this end, the spin structure of the four vectors present in the production vertex is analyzed, and the D-wave mechanism in the tensor production is included. Then, beyond the ratios studied previously involving scalar states and tensor states independently, new ratios relating the scalar and tensor meson productions are estimated. Our results suggest that the D-wave mechanism of tensor production assumes a relevant contribution. New experimental data reporting the angular distributions of these processes will be important for checking this conclusion.
|
