Double transverse spin asymmetry in the p↑pˉ↑p^\uparrow\bar{p}^\uparrow Drell-Yan process from Sivers functions

We show that the transverse double spin asymmetry (DSA) in the Drell-Yan process contributed only from the Sivers functions can be picked out by the weighting function $\frac{Q_T}{M^2}(\cos(\phi-\phi_{S_1})\cos(\phi-\phi_{S_2})+3\sin(\phi-\phi_{S_1})\sin(\phi-\phi_{S_2}))$. The asymmetry is proportional to the product of two Sivers functions from each hadron $f_{1T}^{\perp(1)}\times f_{1T}^{\perp (1)}$. Using two sets of Sivers functions extracted from the semi-inclusive deeply elastic scattering data at HERMES, we estimate this asymmetry in the $p^\uparrow\bar{p}^\uparrow$ Drell-Yan process which is possible to be performed in HESR at GSI. The prediction of DSA in the Drell-Yan process contributed by the function g_{1T}(x,\Vec k_T^2), which can be extracted by the weighting function $\frac{Q_T}{M^2}(3\cos(\phi-\phi_{S_1})\cos(\phi-\phi_{S_2})+\sin(\phi-\phi_{S_1})\sin(\phi-\phi_{S_2}))$, is also given at GSI.Comment: 6 latex pages, 2 figures, to appear in PR

Fermion Masses and Mixings in a S4 Based Model

It has been recently claimed that the symmetry group S4 yields to the Tri-bimaximal neutrino mixing in a "natural" way from the group theory point of view. Approving of this feature as an indication, we build a supersymmetric model of lepton and quark masses based on this family symmetry group. In the lepton sector, a correct mass hierarchy among the charged leptons is achieved together to a neutrino mass matrix which can be diagonalized by the Tri-bimaximal pattern. Our model results to be phenomenologically unequivalent with respect to other proposals based on different flavour groups but still predicting the Tri-bimaximal mixing. In the quark sector a realistic pattern for masses and mixing angles is obtained. The flavour structures of the mass matrices in both the sectors come from the spontaneously symmetry breaking of S4, due to several scalar fields, which get non-zero vacuum expectation values. A specific vacuum alignment is required and it is shown to be a natural results of the minimization of the scalar potential and, moreover, to be stable under the corrections from the higher order terms.Comment: 25 pages, LaTeX; added references and minor correctio

In vivo validation of the electronic depth control probes.

In this article, we evaluated the electrophysiological performance of a novel, high-complexity silicon probe array. This brain-implantable probe implements a dynamically reconfigurable voltage-recording device, coordinating large numbers of electronically switchable recording sites, referred to as electronic depth control (EDC). Our results show the potential of the EDC devices to record good-quality local field potentials, and single- and multiple-unit activities in cortical regions during pharmacologically induced cortical slow wave activity in an animal model

Systematic Parameter Space Search of Extended Quark-Lepton Complementarity

We systematically investigate the parameter space of neutrino and charged lepton mass matrices for textures motivated by an extended quark-lepton complementarity. As the basic hypothesis, we postulate that all mixing angles in U_l and U_nu be either maximal or described by powers of a single small quantity epsilon ~ theta_C. All mass hierarchies are described by this epsilon as well. In this study, we do not assume specific forms for U_l and U_nu, such as large mixing coming from the neutrino sector only. We perform a systematic scan of the 262,144 generated mixing matrices for being compatible with current experimental data, and find a sample of 2,468 possibilities. We then analyze and classify the effective charged lepton and neutrino mass textures, where we especially focus on a subset of models getting under pressure for small theta_13. In addition, we predict the mixing angle distributions from our sample of all valid textures, and study the robustness of this prediction. We also demonstrate how our procedure can be extended to predictions of the Dirac and Majorana phases in U_PMNS. For instance, we find that CP conservation in neutrino oscillations is preferred, and we can impose a lower bound on the mixing matrix element for neutrinoless double beta decay.Comment: 37 pages, 9 figures. Small error in Eq. (36) corrected, and Figs. 8 and 9 updated. Final version matched to Nuclear Physics B version. A detailed list of our textures compatible with current data can be obtained at http://theorie.physik.uni-wuerzburg.de/~winter/Resources/Textures/index.htm

Minimal Mass Matrices for Dirac Neutrinos

We consider the possibility of neutrinos being Dirac particles and study minimal mass matrices with as much zero entries as possible. We find that up to 5 zero entries are allowed. Those matrices predict one vanishing mass state, CP conservation and U_{e3} either zero or proportional to R, where R is the ratio of the solar and atmospheric \Delta m^2. Matrices containing 4 zeros can be classified in categories predicting U_{e3} = 0, U_{e3} \neq 0 but no CP violation or |U_{e3}| \neq 0 and possible CP violation. Some cases allow to set constraints on the neutrino masses. The characteristic value of U_{e3} capable of distinguishing some of the cases with non-trivial phenomenological consequences is about R/2 \sin 2 \theta_{12}. Matrices containing 3 and less zero entries imply (with a few exceptions) no correlation for the observables. We outline models leading to the textures based on the Froggatt-Nielsen mechanism or the non-Abelian discrete symmetry D_4 \times Z_2.Comment: 32 pages, 3 figures. Comments and references added. To appear in JHE

What makes activities strategic: Toward a new framework for strategy‐as‐practice research

Research Abstract: Strategy as practice is one of the most vibrant approaches to strategy research. Yet, there is significant ambiguity around what characterizes an activity as strategic and thus as falling into the domain of strategy as practice. In this article, we address this fundamental concern by differentiating four distinctive views of what qualifies activities as strategic: (1) activities that have important consequences, (2) activities that are labeled strategic, (3) activities carried out by strategists, and (4) activities that perform an important recurrent pattern. Each of these views is associated with different research questions resulting in different research insights. We discuss how the four views together form a new research framework that expands the notion of strategy and thereby the research domain of strategic management.Managerial Summary: Strategy as practice is an important approach to studying strategic management that focuses on strategic activities. However, there is significant ambiguity around what characterizes activities as strategic. In this article, we identify four different views on this question: (1) activities that have important consequences, (2) activities that are labeled strategic, (3) activities carried out by strategists, and (4) activities that perform an important recurrent pattern of activities. Each of these views is associated with different questions and thus with different types of insights. We suggest that the four views together form a research framework that reveals distinctive links between strategy as practice and other lines of strategy research and that expands our notion of strategy and thereby the domain of strategic management

A See-Saw S4S_4 model for fermion masses and mixings

We present a supersymmetric see-saw $S_4$ model giving rise to the most general neutrino mass matrix compatible with Tri-Bimaximal mixing. We adopt the $S_4\times Z_5$ flavour symmetry, broken by suitable vacuum expectation values of a small number of flavon fields. We show that the vacuum alignment is a natural solution of the most general superpotential allowed by the flavour symmetry, without introducing any soft breaking terms. In the charged lepton sector, mass hierarchies are controlled by the spontaneous breaking of the flavour symmetry caused by the vevs of one doublet and one triplet flavon fields instead of using the Froggatt-Nielsen U(1) mechanism. The next to leading order corrections to both charged lepton mass matrix and flavon vevs generate corrections to the mixing angles as large as ${\cal O}(\lambda_C^2)$. Applied to the quark sector, the symmetry group $S_4\times Z_5$ can give a leading order $V_{CKM}$ proportional to the identity as well as a matrix with ${\cal O}(1)$ coefficients in the Cabibbo $2\times 2$ submatrix. Higher order corrections produce non vanishing entries in the other $V_{CKM}$ entries which are generically of ${\cal O}(\lambda_C^2)$.Comment: 30 pages, 3 figures, minor changes to match the published versio

The Fungal Cell Wall : Structure, Biosynthesis, and Function

N.G. is funded by the Wellcome Trust via a senior investigator award and a strategic award and by the MRC Centre for Medical Mycology. C.M. acknowledges the support of the Wellcome Trust and the MRC. N.G. and C.M. are part of the MRC Centre for Medical Mycology. J.P.L. acknowledges support from ANR, Aviesan, and FRM.Peer reviewedPublisher PD

Subleading-twist effects in single-spin asymmetries in semi-inclusive deep-inelastic scattering on a longitudinally polarized hydrogen target

Single-spin asymmetries in the semi-inclusive production of charged pions in deep-inelastic scattering from transversely and longitudinally polarized proton targets are combined to evaluate the subleading-twist contribution to the longitudinal case. This contribution is significantly positive for (\pi^+) mesons and dominates the asymmetries on a longitudinally polarized target previously measured by \hermes. The subleading-twist contribution for (\pi^-) mesons is found to be small

Double hadron leptoproduction in the nuclear medium

First measurement of double-hadron production in deep-inelastic scattering has been measured with the HERMES spectrometer at HERA using a 27.6 GeV positron beam with deuterium, nitrogen, krypton and xenon targets. The influence of the nuclear medium on the ratio of double-hadron to single-hadron yields has been investigated. Nuclear effects are clearly observed but with substantially smaller magnitude and reduced $A$-dependence compared to previously measured single-hadron multiplicity ratios. The data are in fair agreement with models based on partonic or pre-hadronic energy loss, while they seem to rule out a pure absorptive treatment of the final state interactions. Thus, the double-hadron ratio provides an additional tool for studying modifications of hadronization in nuclear matter