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Napiralla, P. et al, & Domingo-Pardo, C. (2020). Benchmarking the PreSPEC@GSI experiment for Coulex-multipolarimetry on the pi(p3/2) -> pi(p1/2) spin-flip transition in 85Br. Eur. Phys. J. A, 56(5), 147–10pp.
Abstract: A first performance test of the Coulomb excitation multipolarimetry (Coulex-multipolarimetry) method is presented. It is based on a 85Br pp3/ 2. pp1/ 2 spinflip experiment performed as part of the PreSPEC-AGATA campaign at the GSI Helmholtzzentrum fur Schwerionen-forschung (GSI). Via determination of background levels around the expected 85Br excitations as well as measured 197Au excitations, an upper limit for the M1 transition strength of the 1/2- 1. 3/2- g.s. transition in 85Br and a lower beam time limit for upcoming experimental campaigns utilizing Coulex-multipolarimetry have been inferred. The impact of the use of AGATA in its anticipated 1p configuration on these estimates is deduced via Geant4 simulations.
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Calibbi, L., Lopez-Ibañez, M. L., Melis, A., & Vives, O. (2020). Muon and electron g – 2 and lepton masses in flavor models. J. High Energy Phys., 06(6), 087–23pp.
Abstract: The stringent experimental bound on μ-> e gamma is compatible with a simultaneous and sizable new physics contribution to the electron and muon anomalous magnetic moments (g – 2)(l) (l = e, mu), only if we assume a non-trivial flavor structure of the dipole operator coefficients. We propose a mechanism in which the realization of the (g – 2)(l) correction is manifestly related to the mass generation through a flavor symmetry. A radiative flavon correction to the fermion mass gives a contribution to the anomalous magnetic moment. In this framework, we introduce a chiral enhancement from a non-trivial O(1) quartic coupling of the scalar potential. We show that the muon and electron anomalies can be simultaneously explained in a vast region of the parameter space with predicted vector-like mediators of masses as large as M chi is an element of [0.6, 2.5] TeV.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of CP observables in B+/- -> DK+/- and B+/- -> D pi+/- with D -> KS0 K+/- pi-/+ decays. J. High Energy Phys., 06(6), 058–25pp.
Abstract: Measurements of CP observables in B-+/- -> DK +/- and B-+/- -> D pi (+/-) decays are presented, where D represents a superposition of D-0 and D<overbar>0 states. The D meson is reconstructed in the three-body final states KS0K +/- pi -/+ and KS0K -/+ pi +/-. The analysis uses samples of B mesons produced in proton-proton collisions, corresponding to an integrated luminosity of 1.0, 2.0, and 6.0 fb(-1) collected with the LHCb detector at centre-of-mass energies of <mml:msqrt>s</mml:msqrt> = 7, 8, and 13 TeV, respectively. These measurements are the most precise to date, and provide important input for the determination of the CKM angle gamma.
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Gariazzo, S. (2020). Constraining power of open likelihoods, made prior-independent. Eur. Phys. J. C, 80(6), 552–6pp.
Abstract: One of the most criticized features of Bayesian statistics is the fact that credible intervals, especially when open likelihoods are involved, may strongly depend on the prior shape and range. Many analyses involving open likelihoods are affected by the eternal dilemma of choosing between linear and logarithmic prior, and in particular in the latter case the situation is worsened by the dependence on the prior range under consideration. In this letter, we revive a simple method to obtain constraints that depend neither on the prior shape nor range and, using the tools of Bayesian model comparison, extend it to overcome the possible dependence of the bounds on the choice of free parameters in the numerical analysis. An application to the case of cosmological bounds on the sum of the neutrino masses is discussed as an example.
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Witte, S. J., Rosauro-Alcaraz, S., McDermott, S. D., & Poulin, V. (2020). Dark photon dark matter in the presence of inhomogeneous structure. J. High Energy Phys., 06(6), 35pp.
Abstract: Dark photon dark matter will resonantly convert into visible photons when the dark photon mass is equal to the plasma frequency of the ambient medium. In cosmological contexts, this transition leads to an extremely efficient, albeit short-lived, heating of the surrounding gas. Existing work in this field has been predominantly focused on understanding the implications of these resonant transitions in the limit that the plasma frequency of the Universe can be treated as being perfectly homogeneous, i.e. neglecting inhomogeneities in the electron number density. In this work we focus on the implications of heating from dark photon dark matter in the presence of inhomogeneous structure (which is particularly relevant for dark photons with masses in the range 10(-15) eV less than or similar to m(A ') less than or similar to 10(-12) eV), emphasizing both the importance of inhomogeneous energy injection, as well as the sensitivity of cosmological observations to the inhomogeneities themselves. More specifically, we derive modified constraints on dark photon dark matter from the Ly-alpha forest, and show that the presence of inhomogeneities allows one to extend constraints to masses outside of the range that would be obtainable in the homogeneous limit, while only slightly relaxing their strength. We then project sensitivity for near-future cosmological surveys that are hoping to measure the 21cm transition in neutral hydrogen prior to reionization, and demonstrate that these experiments will be extremely useful in improving sensitivity to masses near similar to 10(-14) eV, potentially by several orders of magnitude. Finally, we discuss implications for reionization, early star formation, and late-time y-type spectral distortions, and show that probes which are inherently sensitive to the inhomogeneous state of the Universe could resolve signatures unique to the light dark photon dark matter scenario, and thus offer a fantastic potential for a positive detection.
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