Marinas, C., & Vos, M. (2011). The Belle-II DEPFET pixel detector: A step forward in vertexing in the superKEKB flavour factory. Nucl. Instrum. Methods Phys. Res. A, 650(1), 59–63.
Abstract: An upgrade of the successful asymmetric e(+)e(-) collider in KEK (Tsukuba, Japan) is foreseen by the fall of 2013. This new Super Flavor Factory will deliver an increased instantaneous luminosity of up to L = 8 x 10(35) cm(-2) s(-1), 40 times larger than the current KEKB machine. To exploit these new conditions and provide high precision measurements of the decay vertex of the B meson systems, a new silicon vertex detector will be operated in Belle. This new detector will consist of two layers of DEPFET Active Pixel Sensors as close as possible to the interaction point. DEPFET is a field effect transistor, with an additional deep implant underneath the channel's gate, integrated on a completely depleted bulk. This technology offers detection and an in-pixel amplification stage, while keeping low the power consumption. Under these conditions, thin sensors with small pixel size and low intrinsic noise are possible. In this article, an overview of the full system will be described, including the sensor, the front-end electronics and both the mechanical and thermal proposed solutions as well as the expected performance.
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Barenboim, G., & Panotopoulos, G. (2011). Direct neutralino searches in the NMSSM with gravitino LSP in the degenerate scenario. J. High Energy Phys., 08(8), 027–16pp.
Abstract: In the present work a two-component dark matter model is studied adopting the degenerate scenario in the R-parity conserving NMSSM. The gravitino LSP and the neutralino NLSP are extremely degenerate in mass, avoiding the BBN bounds and obtaining a high reheating temperature for thermal leptogenesis. In this model both gravitino (absolutely stable) and neutralino (quasi-stable) contribute to dark matter, and direct detection searches for neutralino are discussed. Points that survive all the constraints correspond to a singlino-like neutralino.
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Hernandez, E., & Nieves, J. (2011). Study of the strong Sigma(b) -> Lambda(b)pi and Sigma*(b) -> Lambda(b)pi in a nonrelativistic quark model. Phys. Rev. D, 84(5), 057902–5pp.
Abstract: We present results for the strong widths corresponding to the Sigma(b) -> Lambda(b)pi and Sigma*(b) -> Lambda(b)pi decays. We apply our model from Phys. Rev. D 72, 094022 (2005), where we previously studied the corresponding transitions in the charmed sector. Our nonrelativistic constituent quark model uses wave functions that take advantage of the constraints imposed by heavy quark symmetry. The partial conservation of axial current hypothesis allows us to determine the strong vertices from an analysis of the axial current matrix elements.
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De Romeri, V., Hirsch, M., & Malinsky, M. (2011). Soft masses in supersymmetric SO(10) GUTs with low intermediate scales. Phys. Rev. D, 84(5), 053012–15pp.
Abstract: The specific shape of the squark, slepton and gaugino mass spectra, if measured with sufficient accuracy, can provide invaluable information not only about the dynamics underpinning their origin at some very high scale such as the unification scale M(G), but also about the intermediate scale physics encountered throughout their renormalization group equations evolution down to the energy scale accessible for the LHC. In this work, we study general features of the TeV scale soft supersymmetry breaking parameters stemming from a generic mSugra configuration within certain classes of supersymmetry SO(10) GUTs with different intermediate symmetries below M(G). We show that particular combinations of soft masses show characteristic deviations from the mSugra limit in different models and thus, potentially, allow to distinguish between these, even if the new intermediate scales are outside the energy range probed at accelerators. We also compare our results to those obtained for the three minimal seesaw models with mSugra boundary conditions and discuss the main differences between those and our SO(10) based models.
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Nieves, J., & Valderrama, M. P. (2011). Deriving the existence of B(B)over-bar* bound states from the X(3872) and heavy quark symmetry. Phys. Rev. D, 84(5), 056015–21pp.
Abstract: We discuss the possibility and the description of bound states between B and (B) over bar* mesons. We argue that the existence of such a bound state can be deduced from (i) the weakly bound X(3872) state, (ii) certain assumptions about the short-range dynamics of the D (D) over bar* system and (iii) heavy quark symmetry. From these assumptions the binding energy of the possible B (B) over bar* bound states is determined, first in a theory containing only contact interactions which serves as a straightforward illustration of the method, and then the effects of including the one-pion exchange potential are discussed. In this latter case three isoscalar states are predicted: a positive and negative C-parity (3)S(1) – (3)D(1) state with a binding energy of 20 MeV and 6 MeV below threshold, respectively, and a positive C-parity (3)P(0) shallow state located almost at the B (B) over bar* threshold. However, large uncertainties are generated as a consequence of the 1/m(Q) corrections from heavy quark symmetry. Finally, the newly discovered isovector Z(b)(10610) state can be easily accommodated within the present framework by a minor modification of the short-range dynamics.
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Jimenez, R., Pena-Garay, C., & Verde, L. (2011). Is it possible to explore Peccei-Quinn axions from frequency-dependence radiation dimming? Phys. Lett. B, 703(3), 232–236.
Abstract: We explore how the Peccei-Quinn (PQ) axion parameter space can be constrained by the frequency-dependence dimming of radiation from astrophysical objects. To do so we perform accurate calculations of photon-axion conversion in the presence of a variable magnetic field. We propose several tests where the PQ axion parameter space can be explored with current and future astronomical surveys: the observed spectra of isolated neutron stars, occultations of background objects by white dwarfs and neutron stars, the light-curves of eclipsing binaries containing a white dwarf. We find that the lack of dimming of the light-curve of a detached eclipsing white dwarf binary recently observed, leads to relevant constraints on the photon-axion conversion. Current surveys designed for Earth-like planet searches are well matched to strengthen and improve the constraints on the PQ axion using astrophysical objects radiation dimming.
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Panotopoulos, G. (2011). A dynamical dark energy model with a given luminosity distance. Gen. Relativ. Gravit., 43(11), 3191–3199.
Abstract: It is assumed that the current cosmic acceleration is driven by a scalar field, the Lagrangian of which is a function of the kinetic term only, and that the luminosity distance is a given function of the red-shift. Upon comparison with baryon acoustic oscillations and cosmic microwave background data the parameters of the models are determined, and then the time evolution of the scalar field is determined by the dynamics using the cosmological equations. We find that the solution is very different than the corresponding solution when the non-relativistic matter is ignored, and that the universe enters the acceleration era at larger red-shift compared to the standard I > CDM model.
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Oset, E., & Ramos, A. (2011). Chiral unitary approach to eta ' N scattering at low energies. Phys. Lett. B, 704(4), 334–342.
Abstract: We study the eta'N interaction within a chiral unitary approach which includes pi N, eta N and related pseudoscalar meson-baryon coupled channels. Since the SU(3) singlet does not contribute to the standard interaction and the eta' is mostly a singlet, the resulting scattering amplitude is very small and inconsistent with the experimental scattering length. The additional consideration of vector meson-baryon states into the coupled channel scheme, via normal and anomalous couplings of pseudoscalar to vector mesons, enhances substantially the eta'N amplitude. We also exploit the freedom of adding to the Lagrangian a new term, allowed by the symmetries of QCD, which couples baryons to the singlet meson of SU(3). Adjusting the unknown strength to the eta'N scattering length, we obtain predictions for the elastic eta'N -> eta'N and inelastic eta'N -> eta N, pi N, K Lambda, K Sigma cross sections at low eta' energies, and discuss their significance.
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de Azcarraga, J. A., & Izquierdo, J. M. (2012). D=3 (p, q)-Poincare supergravities from Lie algebra expansions. Nucl. Phys. B, 854(1), 276–291.
Abstract: We use the expansion of superalgebras procedure (summarized in the text) to derive Chem-Simons (CS) actions for the (p, q)-Poincare supergravities in three-dimensional spacetimes. After deriving the action for the (p, 0)-Poincare supergravity as a CS theory for the expansion osp(p vertical bar 2: R)(2, 1) of osp(p vertical bar 2: R), we find the general (p, q)-Poincare superalgebras and their associated D = 3 supergravity actions as CS gauge theories from an expansion of the simple osp(p + q vertical bar 2, R) superalgebras, namely osp(p + q vertical bar 2, R)(2, 1, 2).
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Perez-Ramos, R., Mathieu, V., & Sanchis-Lozano, M. A. (2011). Three-particle correlations in QCD jets and beyond. J. Phys. G, 38(11), 115007–34pp.
Abstract: In this paper, we present a detailed study of three-particle correlations in quark and gluon jets. We give theoretical results for this observable in the double logarithmic approximation and the modified leading logarithmic approximation. In both resummation schemes, we use the formalism of the generating functional and solve the evolution equations analytically from the steepest descent evaluation of the one-particle distribution. In addition, in this paper we include predictions beyond the limiting spectrum approximation and study this observable near the hump of the single inclusive distribution. We thus provide a further test of the local parton hadron duality and make predictions for the LHC. The computation of higher rank correlators is presented in the double logarithmic approximation and shown to be rather cumbersome.
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