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IDS Collaboration(Lica, R. et al), Algora, A., & Nacher, E. (2025). Revealing the Nature of yrast States in Neutron-Rich Polonium Isotopes. Phys. Rev. Lett., 134(5), 052502–7pp.
Abstract: Polonium isotopes having two protons above the shell closure at Z = 82 show a wide variety of lowlying, high-spin isomeric states across the whole chain. The structure of neutron-deficient isotopes up to 210Po (N = 126) is well established as they are easily produced through various methods. However, there is not much information available for the neutron-rich counterparts for which only selective techniques can be used for their production. We report on the first fast-timing measurements of yrast states up to the 8+ level in 214,216,218Po isotopes produced in the beta- decay of 214,216,218Bi at ISOLDE, CERN. In particular, our new half-life value of 607(14) ps for the 8+1 state in 214Po is nearly 20 times shorter than the value available in the literature and comparable with the newly measured half-lives of 409(16) and 628(25) ps for the corresponding 8+1 states in 216,218Po, respectively. The measured B(E2; 8+1 -> 6+1 ) transition probability values follow an increasing trend relative to isotope mass, reaching a maximum for 216Po. The increase contradicts the previous claims of isomerism for the 8+ yrast states in neutron-rich 214Po and beyond. Together with the other measured yrast transitions, the B(E2) values provide a crucial test of the different theoretical approaches describing the underlying configurations of the yrast band. The new experimental results are compared to shell-model calculations using the KHPE and H 208 effective interactions and their pairing-modified versions, showing an increase in configuration mixing when moving toward the heavier isotopes.
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Reina-Valero, J., Navarro-Madrid, J. R., Blas, D., Diaz-Morcillo, A., Garcia Irastorza, I., Gimeno, B., et al. (2025). High-frequency gravitational waves detection with the BabyIAXO haloscopes. Phys. Rev. D, 111(4), 043024–13pp.
Abstract: We present the first analysis using RADES-BabyIAXO cavities as detectors of high-frequency gravitational waves (HFGWs). In particular, we discuss two configurations for distinct frequency ranges of HFGWs: cavity 1, mostly sensitive at a frequency range of 252.8-333.2 MHz, and cavity 2, at 2.504- 3.402 GHz, which is a scaled down version of cavity 1. We find that cavity 1 will reach sensitivity to strains of the HFGWs of order h1 10-21, while cavity 2 will reach h2 10-20. These represent the best estimations of the RADES-BabyIAXO cavities as HFGW detectors, showing how this setup can produce groundbreaking results in axion physics and HFGWs simultaneously.
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Parada, A., & Sanchez Garcia, G. (2025). Probing neutrino millicharges at the European Spallation Source. Phys. Rev. D, 111(3), 035012–15pp.
Abstract: We study the potential of a set of future detectors, proposed to be located at the European Spallation Source (ESS), to probe neutrino millicharges through coherent elastic neutrino-nucleus scattering. In particular, we focus on detectors with similar characteristics as those that are under development for operation at the ESS, including detection technologies based on cesium iodine, germanium, and noble gases. Under the considered conditions, we show that the Ge detector, with a lighter nuclear target mass with respect to CsI and a noble gas like Xe, is more efficient to constrain neutrino millicharges, reaching a sensitivity of 10-9e for diagonal neutrino millicharges, and 10-8e for the transition ones. In addition, we study the effects of including electron scattering processes for the CsI detector, achieving an expected sensitivity of 10-11e for the diagonal millicharges.
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Gonzalez Suarez, R., Pattnaik, B., & Zurita, J. (2025). Leptophilic Z' bosons at the FCC-ee: Discovery opportunities. Phys. Rev. D, 111(3), 035029–15pp.
Abstract: We examine the possibility to detect new SM-neutral vector bosons (Z') that couple exclusively to leptons in the electron-positron mode of the Future Circular Collider (FCC-ee). Focusing on the Z' production with a radiated photon search channel, we show that the FCC-ee can significantly extend the unprobed parameter space by increasing the exclusion in the coupling by one to two orders of magnitude in the kinematically allowed mass range (from 10 to 365 GeV), with the leading sensitivity being driven by the muon channel. In doing so, it outperforms other proposed lepton collider options such as CLIC and ILC in this range of masses. Further, we discuss the possibility of improving the sensitivity of the FCC-ee to this model through the modification of the dilepton invariant mass resolution and the photon energy resolution. The impact of systematic uncertainties on the expected sensitivities is also studied.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2025). Measurement of the associated production of a top-antitop-quark pair and a Higgs boson decaying into a b(b)over-bar pair in pp collisions at √s=13 TeV using the ATLAS detector at the LHC. Eur. Phys. J. C, 85(2), 210–40pp.
Abstract: This paper reports the measurement of Higgs boson production in association with a t (t) over bar pair in the H -> b (b) over bar decay channel. The analysis uses 140 fb(-1) of 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The final states with one or two electrons or muons are employed. An excess of events over the expected background is found with an observed (expected) significance of 4.6 (5.4) standard deviations. The t (t) over barH cross-section is sigma(t (t) over barH)=411(-92)(+101)fb=411 +/- 54(stat.)(-75)(+85)(syst.)fb for a Higgs boson mass of 125.09 GeV, consistent with the prediction of the Standard Model of 507(-50)(+35) fb. The cross-section is also measured differentially in bins of the Higgs boson transverse momentum within the simplified template cross-section framework.
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