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Antusch, S., Figueroa, D. G., Marschall, K., & Torrenti, F. (2022). Characterizing the postinflationary reheating history: Single daughter field with quadratic-quadratic interaction. Phys. Rev. D, 105(4), 043532–36pp.
Abstract: We study the evolution of the energy distribution and equation of state of the Universe from the end of inflation until the onset of either radiation domination (RD) or a transient period of matter domination (MD). We use both analytical techniques and lattice simulations. We consider two-field models where the inflaton (/) has a monomial potential after inflation V((/)) proportional to i(/) – vip (p 4, and of order similar to 50% for p 4. The system goes to MD at late times for p = 2, while it goes to RD for p > 2. In the later case, we can calculate exactly the number of e-folds until RD as a function of g2, and hence predict accurately inflationary observables like the scalar tilt ns and the tensor-to-scalar ratio r. In the scenario (ii), the energy is always transferred completely to X for p > 2, as long as its effective mass m2X = g2((/) – v)2 is not negligible. For p = 2, the final ratio between the energy densities of X and (/) depends strongly on g2. For all p > 2, the system always goes to MD at late times.
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XENON Collaboration(Aprile, E. et al), & Orrigo, S. E. A. (2017). Results from a calibration of XENON100 using a source of dissolved radon-220. Phys. Rev. D, 95(7), 072008–10pp.
Abstract: A Rn-220 source is deployed on the XENON100 dark matter detector in order to address the challenges in calibration of tonne-scale liquid noble element detectors. We show that the Pb-212 beta emission can be used for low-energy electronic recoil calibration in searches for dark matter. The isotope spreads throughout the entire active region of the detector, and its activity naturally decays below background level within a week after the source is closed. We find no increase in the activity of the troublesome Rn-222 background after calibration. Alpha emitters are also distributed throughout the detector and facilitate calibration of its response to Rn-222. Using the delayed coincidence of Rn-220-Po-216, we map for the first time the convective motion of particles in the XENON100 detector. Additionally, we make a competitive measurement of the half-life of Po-212, t(1/2) = (293.9 +/- (1.0)(stat) +/- (0.6)(sys)) ns.
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XENON100 Collaboration(Aprile, E. et al), & Orrigo, S. E. A. (2016). Low-mass dark matter search using ionization signals in XENON100. Phys. Rev. D, 94(9), 092001–6pp.
Abstract: We perform a low-mass dark matter search using an exposure of 30 kg x yr with the XENON100 detector. By dropping the requirement of a scintillation signal and using only the ionization signal to determine the interaction energy, we lowered the energy threshold for detection to 0.7 keV for nuclear recoils. No dark matter detection can be claimed because a complete background model cannot be constructed without a primary scintillation signal. Instead, we compute an upper limit on the WIMP-nucleon scattering cross section under the assumption that every event passing our selection criteria could be a signal event. Using an energy interval from 0.7 keV to 9.1 keV, we derive a limit on the spin-independent WIMP-nucleon cross section that excludes WIMPs with a mass of 6 GeV/c(2) above 1.4 x 10(-41) cm(2) at 90% confidence level.
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XENON100 Collaboration(Aprile, E. et al), & Orrigo, S. E. A. (2014). First axion results from the XENON100 experiment. Phys. Rev. D, 90(6), 062009–7pp.
Abstract: We present the first results of searches for axions and axionlike particles with the XENON100 experiment. The axion-electron coupling constant, g(Ae), has been probed by exploiting the axioelectric effect in liquid xenon. A profile likelihood analysis of 224.6 live days x 34-kg exposure has shown no evidence for a signal. By rejecting g(Ae) larger than 7.7 x 10(-12) (90% C. L.) in the solar axion search, we set the best limit to date on this coupling. In the frame of the DFSZ and KSVZ models, we exclude QCD axions heavier than 0.3 and 80 eV/c(2), respectively. For axionlike particles, under the assumption that they constitute the whole abundance of dark matter in our galaxy, we constrain gAe to be lower than 1 x 10(-12) (90% C.L.) for masses between 5 and 10 keV/c(2).
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Aranda, A., Bonilla, C., Morisi, S., Peinado, E., & Valle, J. W. F. (2014). Dirac neutrinos from flavor symmetry. Phys. Rev. D, 89(3), 033001–5pp.
Abstract: We present a model where Majorana neutrino mass terms are forbidden by the flavor symmetry group Delta(27). Neutrinos are Dirac fermions and their masses arise in the same way as those of the charged fermions, due to very small Yukawa couplings. The model fits current neutrino oscillation data and correlates the octant of the atmospheric angle theta(23) with the magnitude of the lightest neutrino mass, with maximal mixing excluded for any neutrino mass hierarchy.
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