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Barenboim, G., Bosch, C., Lee, J. S., Lopez-Ibañez, M. L., & Vives, O. (2015). Flavor-changing Higgs boson decays into bottom and strange quarks in supersymmetric models. Phys. Rev. D, 92(9), 095017–15pp.
Abstract: In this work, we explore the flavor-changing decays H-i -> bs in a general supersymmetric scenario. In these models the flavor-changing decays arise at loop level, but-because they originate from a dimension-four operator-they do not decouple and may provide a first sign of new physics for heavy masses beyond the reach of colliders. In the framework of the minimal supersymmetric extension of the Standard Model, we find that the largest branching ratio of the lightest Higgs (H-1) is O(10(-6)) after imposing present experimental constraints, while heavy Higgs states may still present branching ratios O(10(-3)). In a more general supersymmetric scenario, where additional Higgs states may modify the Higgs mixings, the branching ratio BR(H-1 -> bs) can reach values O(10(-4)), while heavy Higgses still remain at O(10(-3)). Although these values are clearly out of reach for the LHC, a full study in a linear collider environment could be worth pursuing.
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Barenboim, G., & Park, W. I. (2015). Spiral inflation with Coleman-Weinberg potential. Phys. Rev. D, 91(6), 063511–5pp.
Abstract: We apply the idea of spiral inflation to the Coleman-Weinberg potential and show that inflation matching our observations well is allowed for a symmetry-breaking scale ranging from an intermediate scale to a grand unified theory (GUT) scale even if the quartic coupling lambda is of O(0.1). The tensor-to-scalar ratio can be of O(0.01) in the case of GUT-scale symmetry breaking.
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Barenboim, G., & Park, W. I. (2015). Spiral inflation. Phys. Lett. B, 741, 252–255.
Abstract: We propose a novel scenario of primordial inflation in which the inflaton goes through a spiral motion starting from around the top of a symmetry breaking potential. We show that, even though inflation takes place for a field value much smaller than Planck scale, it is possible to obtain relatively large tensor-to-scalar ratio (r similar to 0.1) without fine tuning. The inflationary observables perfectly match Planck data.
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Barenboim, G., & Vives, O. (2015). Transplanckian inflation as gravity echoes. Phys. Lett. B, 748, 336–342.
Abstract: In this work, we show that, in the presence of non-minimal coupling to gravity, it is possible to generate sizeable tensor modes in single-field models without transplanckian field values. These transplanckian field values apparently needed in Einstein gravity to accommodate the experimental results may only be due to our insistence of imposing a minimal coupling of the inflaton field to gravity in a model with non-minimal couplings. We present three simple single-field models that prove that it is possible to accommodatea large tensor-to-scalar ratio without requiring transplanckian field values within the slow-roll regime.
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Barrientos, D., Bellato, M., Bazzacco, D., Bortolato, D., Cocconi, P., Gadea, A., et al. (2015). Performance of the Fully Digital FPGA-Based Front-End Electronics for the GALILEO Array. IEEE Trans. Nucl. Sci., 62(6), 3134–3139.
Abstract: In this work we present the architecture and results of a fully digital Front End Electronics (FEE) read out system developed for the GALILEO array. The FEE system, developed in collaboration with the Advanced Gamma Tracking Array (AGATA) collaboration, is composed of three main blocks: preamplifiers, digitizers and preprocessing electronics. The slow control system contains a custom Linux driver, a dynamic library and a server implementing network services. This work presents the first results of the digital FEE system coupled with a GALILEO germanium detector, which has demonstrated the capability to achieve an energy resolution of 1.53% at an energy of 1.33 MeV, similar to the one obtained with a conventional analog system. While keeping a good performance in terms of energy resolution, digital electronics will allow to instrument the full GALILEO array with a versatile system with high integration and low power consumption and costs.
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Barrio, J., Etxebeste, A., Lacasta, C., Muñoz, E., Oliver, J. F., Solaz, C., et al. (2015). Performance of VATA64HDR16 ASIC for medical physics applications based on continuous crystals and SiPMs. J. Instrum., 10, P12001–12pp.
Abstract: Detectors based on Silicon Photomultipliers (SiPMs) coupled to continuous crystals are being tested in medical physics applications due to their potential high resolution and sensitivity. To cope with the high granularity required for a very good spatial resolution, SiPM matrices with a large amount of elements are needed. To be able to read the information coming from each individual channel, dedicated ASICs are employed. The VATA64HDR16 ASIC is a 64-channel, charge-sensitive amplifier that converts the collected charge into a proportional current or voltage signal. A complete assessment of the suitability of that ASIC for medical physics applications based on continuous crystals and SiPMs has been carried out. The input charge range is linear from 20 pC up to 55 pC. The energy resolution obtained at 511 keV is 10% FWHM with a LaBr3 crystal and 16% FWHM with a LYSO crystal. A coincidence timing resolution of 24 ns FWHM is obtained with two LYSO crystals.
Keywords: Solid state detectors; Photon detectors for UV, visible and IR photons (solid-state) (PIN diodes, APDs, Si-PMTs, G-APDs, CCDs, EBCCDs, EMCCDs etc); Front-end electronics for detector readout; Gamma detectors (scintillators, CZT, HPG, HgI etc)
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Bayar, M., Ren, X. L., & Oset, E. (2015). States of rho D*(D)over-bar* with J=3 within the fixed center approximation to the Faddeev equations. Eur. Phys. J. A, 51(5), 61–9pp.
Abstract: We study the interaction of rho, D* and (D) over bar* with spins aligned using the fixed center approximation to the Faddeev equations. We select a cluster of D*(D) over bar*, which is found to be bound in I = 0 and can be associated to the X(3915), and let the rho meson orbit around the D* and (D) over bar*. In this case we find an I = 1 state with mass around 4340 MeV and narrow width of about 50MeV. We also investigate the case with a cluster of rho D* and let the (D) over bar * orbit around the system of the two states. The rho D* cluster is also found to bind and leads to the D-2*(2460) state. The addition of the extra (D) over bar* produces further binding and we find, with admitted uncertainties, a state of I = 0 around 4000MeV, and a less bound narrow state with I = 1 around 4200 MeV.
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Bazeia, D., Lobao, A. S., Losano, L., Menezes, R., & Olmo, G. J. (2015). Braneworld solutions for modified theories of gravity with nonconstant curvature. Phys. Rev. D, 91(12), 124006–11pp.
Abstract: We study braneworld models in the presence of scalar field in a five-dimensional geometry with a single extra dimension of infinite extent, with gravity modified to include a function of the Ricci scalar. We develop a procedure that allows us to obtain an analytical solution for the braneworld configuration in a diversity of models, in the much harder case where the Ricci scalar is a nonconstant quantity.
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Bazeia, D., Losano, L., Menezes, R., Olmo, G. J., & Rubiera-Garcia, D. (2015). Robustness of braneworld scenarios against tensorial perturbations. Class. Quantum Gravity, 32(21), 215011–10pp.
Abstract: Inspired by the peculiarities of the effective geometry of crystalline structures, we reconsider thick brane scenarios from a metric-affine perspective. We show that for a rather general family of theories of gravity, whose Lagrangian is an arbitrary function of the metric and the Ricci tensor, the background and scalar field equations can be written in first-order form, and tensorial perturbations have a non negative definite spectrum, which makes them stable under linear perturbations regardless of the form of the gravity Lagrangian. We find, in particular, that the tensorial zero modes are exactly the same as predicted by Einstein's theory regardless of the scalar field and gravitational Lagrangians.
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Bazeia, D., Losano, L., Menezes, R., Olmo, G. J., & Rubiera-Garcia, D. (2015). Thick brane in f(R) gravity with Palatini dynamics. Eur. Phys. J. C, 75, 569–10pp.
Abstract: This work deals with modified gravity in five dimensional spacetime. We study a thick Palatini f(R) brane, that is, a braneworld scenario described by an anti-de Sitter warped geometry with a single extra dimension of infinite extent, sourced by real scalar field under the Palatini approach, where the metric and the connection are regarded as independent degrees of freedom. We consider a first-order framework which we use to provide exact solutions for the scalar field and warp factor. We also investigate a perturbative scenario such that the Palatini approach is implemented through a Lagrangian f(R)=R+ϵR^n, where the small parameter ϵ controls the deviation from the standard thick brane case.
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