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Gelmini, G. B., Takhistov, V., & Witte, S. J. (2019). Geoneutrinos in large direct detection experiments. Phys. Rev. D, 99(9), 093009–11pp.
Abstract: Geoneutrinos can provide a unique insight into Earth's interior, its central engine, and its formation history. We study the detection of geoneutrinos in large direct detection experiments, which has been considered nonfeasible. We compute the geoneutrino-induced electron and nuclear recoil spectra in different materials, under several optimistic assumptions. We identify germanium as the most promising target element due to the low nuclear recoil energy threshold that could be achieved. The minimum exposure required for detection would be O(10) ton-years. The realistic low thresholds achievable in germanium and silicon permit the detection of K-40 geoneutrinos. These are particularly important to determining Earth's formation history, but they are below the kinematic threshold of inverse beta decay, the detection process used in scintillator-based experiments.
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Gottardo, A. et al, Gadea, A., & Algora, A. (2019). New spectroscopic information on Tl-211,Tl-213: A changing structure beyond the N=126 shell closure. Phys. Rev. C, 99(5), 054326–7pp.
Abstract: The neutron-rich isotopes Tl-211,Tl-213, beyond the N = 126 shell closure, have been studied for the first time in isomer gamma-ray decay, exploiting the fragmentation of a primary uranium beam at the Fragment Separator-Rare Isotopes Investigation at GSI setup. The observed isomeric states in Tl-211,Tl-213 show a deviation from the seniority-like scheme of Tl-209. The possible interpretation of the data is discussed on the basis of energy-level systematics and shell-model calculations.
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Diel, F., Fujita, Y., Fujita, H., Cappuzzello, F., Ganioglu, E., Grewe, E. W., et al. (2019). High-resolution study of the Gamow-Teller (GT_) strength in the Zn-64(He-3, t) Ga-64 reaction. Phys. Rev. C, 99(5), 054322–10pp.
Abstract: Gamow-Teller (GT) transitions starting from the T-z = +2 nucleus Zn-64 to the T-z = +1 nucleus Ga-64 were studied in a (p, n)-type (He-3,t) charge-exchange reaction at a beam energy of 140 MeV/nucleon and scattering angles close to 0 degrees. Here, T-z is the z component of the isospin T. The experiment was conducted at the Research Center for Nuclear Physics (RCNP) in Osaka, Japan. An energy resolution of approximate to 34 keV was achieved by applying beam matching techniques to the Grand Raiden magnetic spectrometer system. With our good resolution, we could observe GT strength fragmented in many states up to an excitation energy of approximate to 11 MeV. By performing angular distribution analysis, we could identify states in Ga-64 excited by GT transitions. The reduced GT transition strengths [B(GT)values] were calculated assuming the proportionality between the cross sections and the B(GT)values. Shell-model calculations using the GXPF1J interaction reproduced the B(GT)strength distribution throughout the spectrum. States with isospin T = 3 were identified by comparing the Zn-64(He-3,t)Ga-64 spectrum with a Zn-64(d, He-2)Cu-64 spectrum. Relative excitation energies of the corresponding structures are in good agreement, supporting the robustness of isospin symmetry in the mass number A = 64 nuclei.
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Barenboim, G., & Park, W. I. (2019). Spontaneous baryogenesis in spiral inflation. Eur. Phys. J. C, 79(6), 456–11pp.
Abstract: We examined the possibility of spontaneous baryogenesis driven by the inflaton in the scenario of spiral inflation, and found the parametric dependence of the late-time baryon number asymmetry. As a result, it is shown that, depending on the effective coupling of baryon/lepton number violating operators, it is possible to obtain the right amount of asymmetry even in the presence of a matter-domination era as long as such era is relatively short. In a part of the parameter space, the required expansion rate during inflation is close to the current upper-bound, and hence can be probed in the near future experiments.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Barranco Navarro, L., Cabrera Urban, S., et al. (2019). Search for heavy charged long-lived particles in the ATLAS detector in 36.1 fb(-1) of proton-proton collision data at root s=13 Te V. Phys. Rev. D, 99(9), 092007–34pp.
Abstract: A search for heavy charged long-lived particles is performed using a data sample of 36.1 fb(-1) of protonproton collisions at root s = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. The search is based on observables related to ionization energy loss and time of flight, which are sensitive to the velocity of heavy charged particles traveling significantly slower than the speed of light. Multiple search strategies for a wide range of lifetimes, corresponding to path lengths of a few meters, are defined as model independently as possible, by referencing several representative physics cases that yield long-lived particles within supersymmetric models, such as gluinos/squarks (R-hadrons), charginos and staus. No significant deviations from the expected Standard Model background are observed. Upper limits at 95% confidence level are provided on the production cross sections of long-lived R-hadrons as well as directly pair-produced staus and charginos. These results translate into lower limits on the masses of long-lived gluino, sbottom and stop R-hadrons, as well as staus and charginos of 2000, 1250, 1340, 430, and 1090 GeV, respectively.
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