Simple-minded unitarity constraint and an application to unparticles
International Nuclear Information System (INIS)
Delgado, Antonio; Strassler, Matthew J.
2010-01-01
Unitarity, a powerful constraint on new physics, has not always been properly accounted for in the context of hidden sectors. Feng, Rajaraman, and Tu have suggested that large (pb to nb) multiphoton or multilepton signals could be generated at the LHC through the three-point functions of a conformally invariant hidden sector (an 'unparticle' sector). Because of the conformal invariance, the kinematic distributions are calculable. However, the cross sections for many such processes grow rapidly with energy, and at some high scale, to preserve unitarity, conformal invariance must break down. Requiring that conformal invariance not be broken, and that no signals be already observed at the Tevatron, we obtain a strong unitarity bound on multiphoton events at the (10 TeV) LHC. For the model of Feng et al., even with extremely conservative assumptions, cross sections must be below 25 fb, and for operator dimension near 2, well below 1 fb. In more general models, four-photon signals could still reach cross sections of a few pb, though bounds below 200 fb are more typical. Our methods apply to a wide variety of other processes and settings.
Unitarity constraints on trimaximal mixing
International Nuclear Information System (INIS)
Kumar, Sanjeev
2010-01-01
When the neutrino mass eigenstate ν 2 is trimaximally mixed, the mixing matrix is called trimaximal. The middle column of the trimaximal mixing matrix is identical to tribimaximal mixing and the other two columns are subject to unitarity constraints. This corresponds to a mixing matrix with four independent parameters in the most general case. Apart from the two Majorana phases, the mixing matrix has only one free parameter in the CP conserving limit. Trimaximality results in interesting interplay between mixing angles and CP violation. A notion of maximal CP violation naturally emerges here: CP violation is maximal for maximal 2-3 mixing. Similarly, there is a natural constraint on the deviation from maximal 2-3 mixing which takes its maximal value in the CP conserving limit.
QCD unitarity constraints on Reggeon Field Theory
Energy Technology Data Exchange (ETDEWEB)
Kovner, Alex [Physics Department, University of Connecticut,2152 Hillside Road, Storrs, CT 06269 (United States); Levin, Eugene [Departemento de Física, Universidad Técnica Federico Santa María,and Centro Científico-Tecnológico de Valparaíso,Avda. Espana 1680, Casilla 110-V, Valparaíso (Chile); Department of Particle Physics, Tel Aviv University,Tel Aviv 69978 (Israel); Lublinsky, Michael [Physics Department, Ben-Gurion University of the Negev,Beer Sheva 84105 (Israel); Physics Department, University of Connecticut,2152 Hillside Road, Storrs, CT 06269 (United States)
2016-08-04
We point out that the s-channel unitarity of QCD imposes meaningful constraints on a possible form of the QCD Reggeon Field Theory. We show that neither the BFKL nor JIMWLK nor Braun’s Hamiltonian satisfy the said constraints. In a toy, zero transverse dimensional case we construct a model that satisfies the analogous constraint and show that at infinite energy it indeed tends to a “black disk limit' as opposed to the model with triple Pomeron vertex only, routinely used as a toy model in the literature.
QCD unitarity constraints on Reggeon Field Theory
International Nuclear Information System (INIS)
Kovner, Alex; Levin, Eugene; Lublinsky, Michael
2016-01-01
We point out that the s-channel unitarity of QCD imposes meaningful constraints on a possible form of the QCD Reggeon Field Theory. We show that neither the BFKL nor JIMWLK nor Braun’s Hamiltonian satisfy the said constraints. In a toy, zero transverse dimensional case we construct a model that satisfies the analogous constraint and show that at infinite energy it indeed tends to a “black disk limit' as opposed to the model with triple Pomeron vertex only, routinely used as a toy model in the literature.
Perturbative unitarity constraints on gauge portals
El Hedri, Sonia; Shepherd, William; Walker, Devin G. E.
2017-12-01
Dark matter that was once in thermal equilibrium with the Standard Model is generally prohibited from obtaining all of its mass from the electroweak phase transition. This implies a new scale of physics and mediator particles to facilitate dark matter annihilation. In this work, we focus on dark matter that annihilates through a generic gauge boson portal. We show how partial wave unitarity places upper bounds on the dark gauge boson, dark Higgs and dark matter masses. Outside of well-defined fine-tuned regions, we find an upper bound of 9 TeV for the dark matter mass when the dark Higgs and dark gauge bosons both facilitate the dark matter annihilations. In this scenario, the upper bound on the dark Higgs and dark gauge boson masses are 10 TeV and 16 TeV, respectively. When only the dark gauge boson facilitates dark matter annihilations, we find an upper bound of 3 TeV and 6 TeV for the dark matter and dark gauge boson, respectively. Overall, using the gauge portal as a template, we describe a method to not only place upper bounds on the dark matter mass but also on the new particles with Standard Model quantum numbers. We briefly discuss the reach of future accelerator, direct and indirect detection experiments for this class of models.
Unitarity constraints in the construction of optical potentials
International Nuclear Information System (INIS)
Cannata, F.; Deponder, J.P.; Lenz, F.
1982-01-01
We first review the unitarity properties of the first order optical potential theory which arise from the one-body nature of both the single scattering approximation and of the single particle model for the nucleus. We construct optical potentials relaxing either the independent particle guided by the requirement of incorporating the minimal unitary of the first order theory and extending it to more complex situations. Our investigation of the effects of nucleon-nucleon residual interaction results in a description of the quasifree mechanism modified by final state unitarity requires the inclusion of all possible scattering processes on a given pair of target nucleons. This naturally leads to a formation of the optical potential in terms of three-body rather than two-body amplitudes. We discuss various approximation which make, in combination with phenomenological ingredients, an evaluation of these optical potentials feasible
Constraints on the ωπ Form Factor from Analyticity and Unitarity
Ananthanarayan, B.; Caprini, Irinel; Kubis, Bastian
Form factors are important low-energy quantities and an accurate knowledge of these sheds light on the strong interactions. A variety of methods based on general principles have been developed to use information known in different energy regimes to constrain them in regions where experimental information needs to be tested precisely. Here we review our recent work on the electromagnetic ωπ form factor in a model-independent framework known as the method of unitarity bounds, partly motivated by the discre-pancies noted recently between the theoretical calculations of the form factor based on dispersion relations and certain experimental data measured from the decay ω → π0γ*. We have applied a modified dispersive formalism, which uses as input the discontinuity of the ωπ form factor calculated by unitarity below the ωπ threshold and an integral constraint on the square of its modulus above this threshold. The latter constraint was obtained by exploiting unitarity and the positivity of the spectral function of a QCD correlator, computed on the spacelike axis by operator product expansion and perturbative QCD. An alternative constraint is obtained by using data available at higher energies for evaluating an integral of the modulus squared with a suitable weight function. From these conditions we derived upper and lower bounds on the modulus of the ωπ form factor in the region below the ωπ threshold. The results confirm the existence of a disagreement between dispersion theory and experimental data on the ωπ form factor around 0:6 GeV, including those from NA60 published in 2016.
Constraints on the Kl3 form factors from analyticity and unitarity
Indian Academy of Sciences (India)
2012-10-05
in. Abstract. The Kπ form factors are investigated at low energies by the method of unitarity bounds adapted so as to include information on the phase and modulus along the elastic region of the unitarity cut. Using as input the ...
Unitarity constraints in the standard model with a singlet scalar field
International Nuclear Information System (INIS)
Kang, Sin Kyu; Park, Jubin
2015-01-01
Motivated by the discovery of a new scalar field and amelioration of the electroweak vacuum stability ascribed to a singlet scalar field embedded in the standard model (SM), we examine the implication of the perturbative unitarity in the SM with a singlet scalar field. Taking into account the full contributions to the scattering amplitudes, we derive unitarity conditions on the scattering matrix which can be translated into bounds on the masses of the scalar fields. In the case that the singlet scalar field develops vacuum expectation value (VEV), we get the upper bound on the singlet scalar mass varying with the mixing between the singlet and Higgs scalars. On the other hand, the mass of the Higgs scalar can be constrained by the unitarity condition in the case that the VEV of the singlet scalar is not generated. Applying the upper bound on the Higgs mass to the scenario of the unitarized Higgs inflation, we discuss how the unitarity condition can constrain the Higgs inflation. The singlet scalar mass is not constrained by the unitarity itself when we impose Z 2 in the model because of no mixing with the Higgs scalar. But, regarding the singlet scalar field as a cold dark matter candidate, we derive upper bound on the singlet scalar mass by combining the observed relic abundance with the unitarity condition.
Constraints on the [Formula: see text] form factor from analyticity and unitarity.
Ananthanarayan, B; Caprini, I; Kubis, B
Motivated by the discrepancies noted recently between the theoretical calculations of the electromagnetic [Formula: see text] form factor and certain experimental data, we investigate this form factor using analyticity and unitarity in a framework known as the method of unitarity bounds. We use a QCD correlator computed on the spacelike axis by operator product expansion and perturbative QCD as input, and exploit unitarity and the positivity of its spectral function, including the two-pion contribution that can be reliably calculated using high-precision data on the pion form factor. From this information, we derive upper and lower bounds on the modulus of the [Formula: see text] form factor in the elastic region. The results provide a significant check on those obtained with standard dispersion relations, confirming the existence of a disagreement with experimental data in the region around [Formula: see text].
Constraints on the ωπ form factor from analyticity and unitarity
International Nuclear Information System (INIS)
Ananthanarayan, B.; Caprini, I.; Kubis, B.
2014-01-01
Motivated by the discrepancies noted recently between the theoretical calculations of the electromagnetic ωπ form factor and certain experimental data, we investigate this form factor using analyticity and unitarity in a framework known as the method of unitarity bounds. We use a QCD correlator computed on the spacelike axis by operator product expansion and perturbative QCD as input, and exploit unitarity and the positivity of its spectral function, including the two-pion contribution that can be reliably calculated using high-precision data on the pion form factor. From this information, we derive upper and lower bounds on the modulus of the ωπ form factor in the elastic region. The results provide a significant check on those obtained with standard dispersion relations, confirming the existence of a disagreement with experimental data in the region around 0.6 GeV. (orig.)
Constraints on the ωπ form factor from analyticity and unitarity
Energy Technology Data Exchange (ETDEWEB)
Ananthanarayan, B. [Indian Institute of Science, Centre for High Energy Physics, Bangalore (India); Caprini, I. [Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O.B. MG-6, Magurele (Romania); Kubis, B. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen-und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Bonn (Germany)
2014-12-01
Motivated by the discrepancies noted recently between the theoretical calculations of the electromagnetic ωπ form factor and certain experimental data, we investigate this form factor using analyticity and unitarity in a framework known as the method of unitarity bounds. We use a QCD correlator computed on the spacelike axis by operator product expansion and perturbative QCD as input, and exploit unitarity and the positivity of its spectral function, including the two-pion contribution that can be reliably calculated using high-precision data on the pion form factor. From this information, we derive upper and lower bounds on the modulus of the ωπ form factor in the elastic region. The results provide a significant check on those obtained with standard dispersion relations, confirming the existence of a disagreement with experimental data in the region around 0.6 GeV. (orig.)
International Nuclear Information System (INIS)
Frampton, Paul H.; He Xiaogang
2010-01-01
For the three family quark flavor mixing, the best parametrization is the original Kobayashi-Maskawa matrix, V KM , with four real parameters: three rotation angles θ 1,2,3 and one phase δ. A popular way of presentation is by the unitarity triangle which, however, explicitly displays only three, not four, independent parameters. Here we propose an alternative presentation which displays simultaneously all four parameters: the unitarity boomerang.
Energy Technology Data Exchange (ETDEWEB)
Frampton, Paul H. [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan); Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255 (United States); He Xiaogang, E-mail: hexg@phys.ntu.edu.t [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan); Department of Physics and Center for Theoretical Sciences, National Taiwan University, Taipei, Taiwan (China)
2010-04-26
For the three family quark flavor mixing, the best parametrization is the original Kobayashi-Maskawa matrix, V{sub KM}, with four real parameters: three rotation angles theta{sub 1,2,3} and one phase delta. A popular way of presentation is by the unitarity triangle which, however, explicitly displays only three, not four, independent parameters. Here we propose an alternative presentation which displays simultaneously all four parameters: the unitarity boomerang.
Baryons and dual unitarization
International Nuclear Information System (INIS)
Konishi, K.-I.
1977-05-01
Processes involving baryons are discussed in the scheme of dual unitarization. In particular, the topological expansion is generalized to any hadronic S-matrix elements involving baryons and/or mesons. The expansion is based on a model for the baryon propagator, which is a set of three planar Feynman diagrams joined at a junction line. The resulting expansion is a double expansion in 1/N (N = the number of quark flavours) and in the number of baryon loops. Based on this, several new observations are made in phenomenological problems, and a unifying point of view in stressed. The scheme is evidently crossing invariant, and unitarity constraints are imposed order by order in 1/N and in the baryon loop number. (author)
Building up reggeons and the pomeron from duality and unitarity
International Nuclear Information System (INIS)
Sakai, N.
1975-07-01
The subject is treated under the following headings: duality; unitarity; duality and unitarity; 1/N expansion; Reggeon bootstrap; Pomeron equation; triple Pomeron. The results are summarized: (1) combining duality with unitarity, powerful constraints are obtained; (2) many phenomenological successes have been obtained since some practical methods of calculation were devised; and (3) even the complete unitarization is hopeful; 1/N expansion may be useful for this purpose. (author)
New analytic unitarization schemes
International Nuclear Information System (INIS)
Cudell, J.-R.; Predazzi, E.; Selyugin, O. V.
2009-01-01
We consider two well-known classes of unitarization of Born amplitudes of hadron elastic scattering. The standard class, which saturates at the black-disk limit includes the standard eikonal representation, while the other class, which goes beyond the black-disk limit to reach the full unitarity circle, includes the U matrix. It is shown that the basic properties of these schemes are independent of the functional form used for the unitarization, and that U matrix and eikonal schemes can be extended to have similar properties. A common form of unitarization is proposed interpolating between both classes. The correspondence with different nonlinear equations are also briefly examined.
Tree-level unitarity and renormalizability in Lifshitz scalar theory
International Nuclear Information System (INIS)
Fujimori, Toshiaki; Inami, Takeo; Izumi, Keisuke; Kitamura, Tomotaka
2016-01-01
We study unitarity and renormalizability in the Lifshitz scalar field theory, which is characterized by an anisotropic scaling between the space and time directions. Without the Lorentz symmetry, both the unitarity and the renormalizability conditions are modified from those in relativistic theories. We show that for renormalizability, an extended version of the power-counting condition is required in addition to the conventional one. The unitarity bound for S-matrix elements also gives stronger constraints on interaction terms because of the reference frame dependence of scattering amplitudes. We prove that both unitarity and renormalizability require identical conditions as in the case of conventional relativistic theories
Generalized eikonalization and unitarity
Energy Technology Data Exchange (ETDEWEB)
Giffon, M. [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire; Predazzi, E. [Universita di Torino (Italy); Martynov, E.
1996-12-31
In the literature, the notion of eikonalization is often used as synonymous of unitarization or, at least, as implying that unitarity is not violated. This, to the very least, appears to be wishful thinking. We discuss the properties of various types of eikonalization within a unified treatment. Linear trajectories with intercept larger than unity (so popular nowadays) lead to small asymptotic violations of unitarity even after eikonalization. Classes of eikonalizations in which the Odderon could dominate over the Pomeron are given; even so the maximal Odderon is still excluded by eikonalization. (authors). 18 refs.
Generalized eikonalization and unitarity
International Nuclear Information System (INIS)
Giffon, M.; Martynov, E.
1996-01-01
In the literature, the notion of eikonalization is often used as synonymous of unitarization or, at least, as implying that unitarity is not violated. This, to the very least, appears to be wishful thinking. We discuss the properties of various types of eikonalization within a unified treatment. Linear trajectories with intercept larger than unity (so popular nowadays) lead to small asymptotic violations of unitarity even after eikonalization. Classes of eikonalizations in which the Odderon could dominate over the Pomeron are given; even so the maximal Odderon is still excluded by eikonalization. (authors)
Geometric ghosts and unitarity
International Nuclear Information System (INIS)
Ne'eman, Y.
1980-09-01
A review is given of the geometrical identification of the renormalization ghosts and the resulting derivation of Unitarity equations (BRST) for various gauges: Yang-Mills, Kalb-Ramond, and Soft-Group-Manifold
Giudice, Gian F
2011-01-01
We consider a simple extension of the Standard Model Higgs inflation with one new real scalar field which preserves unitarity up to the Planck scale. The new scalar field (called sigma) completes in the ultraviolet the theory of Higgs inflation by linearizing the Higgs kinetic term in the Einstein frame, just as the non-linear sigma model is unitarized into its linear version. The unitarity cutoff of the effective theory, obtained by integrating out the sigma field, varies with the background value of the Higgs field. In our setup, both the Higgs field and the sigma field participate in the inflationary dynamics, following the flat direction of the potential. We obtain the same slow-roll parameters and spectral index as in the original Higgs inflation but we find that the Hubble rate during inflation depends not only on the Higgs self-coupling, but also on the unknown couplings of the sigma field.
International Nuclear Information System (INIS)
Giudice, Gian F.; Lee, Hyun Min
2011-01-01
We consider a simple extension of the Standard Model Higgs inflation with one new real scalar field which preserves unitarity up to the Planck scale. The new scalar field (called sigma) completes in the ultraviolet the theory of Higgs inflation by linearizing the Higgs kinetic term in the Einstein frame, just as the non-linear sigma model is unitarized into its linear version. The unitarity cutoff of the effective theory, obtained by integrating out the sigma field, varies with the background value of the Higgs field. In our setup, both the Higgs field and the sigma field participate in the inflationary dynamics, following the flat direction of the potential. We obtain the same slow-roll parameters and spectral index as in the original Higgs inflation but we find that the Hubble rate during inflation depends not only on the Higgs self-coupling, but also on the unknown couplings of the sigma field.
Saleem, M
2002-01-01
The Unitarity of the CKM matrix is examined in the light of the latest available accurate data. The analysis shows that a conclusive result cannot be derived at present. Only more precise data can determine whether the CKM matrix opens new vistas beyond the standard model or not.
Brustein, Ram
2011-01-01
We reconsider, from a novel perspective, how unitarity constrains the corrections to the ratio of shear viscosity \\eta\\ to entropy density s. We start with higher-derivative extensions of Einstein gravity in asymptotically anti-de Sitter spacetimes. It is assumed that these theories are derived from string theory and thus have a unitary UV completion that is dual to a unitary, UV-complete boundary gauge theory. We then propose that the gravitational perturbations about a solution of the UV complete theory are described by an effective theory whose linearized equations of motion have at most two time derivatives. Our proposal leads to a concrete prescription for the calculation of \\eta/s for theories of gravity with arbitrary higher-derivative corrections. The resulting ratio can take on values above or below 1/4\\pi\\ and is consistent with all the previous calculations, even though our reasoning is substantially different. For the purpose of calculating \\eta/s, our proposal also leads to only two possible cand...
Unitarity relations in c=1 Liouville theory
International Nuclear Information System (INIS)
Lowe, D.A.
1992-01-01
In this paper, the authors consider the S-matrix of c = 1 Liouville theory with vanishing cosmological constant. The authors examine some of the constraints imposed by unitarity. These completely determine (N,2) amplitudes at tree level in terms of the (N,1) amplitudes when the plus tachyon momenta take generic values. A surprising feature of the matrix model results is the lack of particle creation branch cuts in the higher genus amplitudes. In fact, the authors show that the naive field theory limit of Liouville theory would predict such branch cuts. However, unitarity in the full string theory ensures that such cuts do not appear in genus one (N,1) amplitudes. The authors conclude with some comments about the genus one (N,2) amplitudes
Dremin, I. M.
I begin with a tribute to V.N. Gribov and then come to a particular problem which would be of interest for him. His first paper on reggeology was devoted to elastic scatterings of hadrons. Here, using the unitarity relation in combination with experimental data about the elastic scattering in the diffraction cone, I show how the shape and the darkness of the interaction region of colliding protons change with the increase of their energies. In particular, the collisions become fully absorptive at small impact parameters at LHC energies that results in some special features of inelastic processes as well. The possible evolution with increasing energy of the shape from the dark core at the LHC to the fully transparent one at higher energies is discussed. It implies that the terminology of the black disk would be replaced by the black torus.
Causality and unitarity via the tree-loop duality relation
Energy Technology Data Exchange (ETDEWEB)
Tomboulis, E.T. [Mani L. Bhaumik Institute for Theoretical Physics,Department of Physics and Astronomy, UCLA,Los Angeles, CA 90095-1547 (United States)
2017-05-29
The tree-loop duality relation is used as a starting point to derive the constraints of causality and unitarity. Specifically, the Bogoliubov causality condition is ab initio derived at the individual graph level. It leads to a representation of a graph in terms of lower order cut graphs. Extracting the absorptive part gives then the general unitarity relation (Cutkosky rule). The derivation, being carried out directly in momentum space, holds for any local (polynomial) hermitian interaction vertices. This is in contrast to the technical difficulties arising from contact terms in the spacetime approach based on the largest time equation.
Unitarity corrections and high field strengths in high energy hard collisions
International Nuclear Information System (INIS)
Kovchegov, Y.V.; Mueller, A.H.
1997-01-01
Unitarity corrections to the BFKL description of high energy hard scattering are viewed in large N c QCD in light-cone quantization. In a center of mass frame unitarity corrections to high energy hard scattering are manifestly perturbatively calculable and unrelated to questions of parton saturation. In a frame where one of the hadrons is initially at rest unitarity corrections are related to parton saturation effects and involve potential strengths A μ ∝1/g. In such a frame we describe the high energy scattering in terms of the expectation value of a Wilson loop. The large potentials A μ ∝1/g are shown to be pure gauge terms allowing perturbation theory to again describe unitarity corrections and parton saturation effects. Genuine nonperturbative effects only come in at energies well beyond those energies where unitarity constraints first become important. (orig.)
Implications of perturbative unitarity for scalar di-boson resonance searches at LHC
Di Luzio, Luca; Nardecchia, Marco
2017-01-01
We study the constraints implied by partial wave unitarity on new physics models explaining the LHC di-photon excess at 750 GeV. We argue that the effective description in terms of the SM supplemented by a single scalar resonance breaks down at scales of few tens of TeV, where perturbative unitarity is violated due to the large cross-section required in order to fit the $\\gamma\\gamma$ signal. Likewise, we use unitarity arguments in order to set perturbativity bounds on renormalizable UV completions of the EFT description. We finally discuss under which conditions the data can be accommodated within weakly-coupled models.
Update of the Unitarity Triangle Analysis
Bevan, A.J.; Ciuchini, M.; Derkach, D.; Stocchi, A.; Franco, E.; Silvestrini, L.; Lubicz, V.; Tarantino, Cecilia; Martinelli, G.; Parodi, F.; Schiavi, C.; Pierini, M.; Sordini, V.; Vagnoni, V.
2010-01-01
We present the status of the Unitarity Triangle Analysis (UTA), within the Standard Model (SM) and beyond, with experimental and theoretical inputs updated for the ICHEP 2010 conference. Within the SM, we find that the general consistency among all the constraints leaves space only to some tension (between the UTA prediction and the experimental measurement) in BR(B -> tau nu), sin(2 beta) and epsilon_K. In the UTA beyond the SM, we allow for New Physics (NP) effects in (Delta F)=2 processes. The hint of NP at the 2.9 sigma level in the B_s-\\bar B_s mixing turns out to be confirmed by the present update, which includes the new D0 result on the dimuon charge asymmetry but not the new CDF measurement of phi_s, being the likelihood not yet released.
Dual topological unitarization -- phenomenological aspect
International Nuclear Information System (INIS)
Tan, C.I.
1978-01-01
An assessment is provided on the viability of dual topological unitarization as a practical scheme for organizing and interpreting hadronic phenomena at current machine energies. Previous detailed reviews are complemented, with emphasis on phenomenological aspects and more recent developments. Diffraction scattering, a test of P--f identity hypothesis, the flavor model, the P--f identity versus the Veneziano two-jet picture, and an illustration of the new phenomenology are included. 24 references
Anomalies, Unitarity and Quantum Irreversibility
Anselmi, D
1999-01-01
The trace anomaly in external gravity is the sum of three terms at criticality: the square of the Weyl tensor, the Euler density and Box R, with coefficients, properly normalized, called c, a and a', the latter being ambiguously defined by an additive constant. Unitarity and positivity properties of the induced actions allow us to show that the total RG flows of a and a' are equal and therefore the a'-ambiguity can be consistently removed through the identification a'=a. The picture that emerges clarifies several long-standing issues. The interplay between unitarity and renormalization implies that the flux of the renormalization group is irreversible. A monotonically decreasing a-function interpolating between the appropriate values is naturally provided by a'. The total a-flow is expressed non-perturbatively as the invariant (i.e. scheme-independent) area of the graph of the beta function between the fixed points. We test this prediction to the fourth loop order in perturbation theory, in QCD with Nf ~< ...
Lattice QCD inputs to the CKM unitarity triangle analysis
International Nuclear Information System (INIS)
Laiho, Jack; Lunghi, E.; Van de Water, Ruth S.
2010-01-01
We perform a global fit to the Cabibbo-Kobayashi-Maskawa unitarity triangle using the latest experimental and theoretical constraints. Our emphasis is on the hadronic weak matrix elements that enter the analysis, which must be computed using lattice QCD or other nonperturbative methods. Realistic lattice QCD calculations which include the effects of the dynamical up, down, and strange quarks are now available for all of the standard inputs to the global fit. We therefore present lattice averages for all of the necessary hadronic weak matrix elements. We attempt to account for correlations between lattice QCD results in a reasonable but conservative manner: whenever there are reasons to believe that an error is correlated between two lattice calculations, we take the degree of correlation to be 100%. These averages are suitable for use as inputs both in the global Cabibbo-Kobayashi-Maskawa unitarity triangle fit and other phenomenological analyses. In order to illustrate the impact of the lattice averages, we make standard model predictions for the parameters B-circumflex K , |V cb |, and |V ub |/|V cb |. We find a (2-3)σ tension in the unitarity triangle, depending upon whether we use the inclusive or exclusive determination of |V cb |. If we interpret the tension as a sign of new physics in either neutral kaon or B mixing, we find that the scenario with new physics in kaon mixing is preferred by present data.
Update of the Unitarity Triangle Analysis
International Nuclear Information System (INIS)
Tarantino, C.; Bona, M.; Sordini, V.
2009-01-01
We present the update of the Unitarity Triangle (UT) analysis within the Standard Model (SM) and beyond. Within the SM, combining the direct measurements on sides and angles, the UT turns out to be overconstraint in a consistent way, showing that the CKM matrix is the dominant source of flavour mixing and CP-violation and that New Physics (NP) effects can appear at most as small corrections to the CKM picture. Generalizing the UT analysis to investigate NP effects, constraints on b → s transitions are also included and both CKM and NP parameters are fitted simultaneously. While no evidence of NP effects is found in K - (bar) K and B d - (bar) B d mixing, in the B s - (bar) B s mixing an hint of NP is found. The UT analysis beyond the SM also allows us to derive bounds on the coefficients of the most general ΔF = 2 effective Hamiltonian, that can be translated into bounds on the NP scale. (authors)
Diffusion into infrared and unitarization of the Balitskii-Fadin-Kuraev-Lipatov Pomeron
International Nuclear Information System (INIS)
Golec-Biernat, K.; Motyka, L.; Stasto, A.M.
2002-01-01
The Balitskii-Fadin-Kuraev-Lipatov (BFKL) Pomeron in perturbative QCD is plagued by the lack of unitarity and diffusion into the infrared region of gluon virtualities. These two problems are intimately related. We perform numerical studies of the evolution equation proposed by Balitskii and Kovchegov which unitarizes the BFKL Pomeron. We show how diffusion into the infrared region is suppressed due to the emergence of a saturation scale and scaling behavior. We study the universality of this phenomenon as well as its dependence on subleading corrections to the BFKL Pomeron such as the running coupling and kinematic constraint. These corrections are very important for phenomenological applications
Implications of perturbative unitarity for scalar di-boson resonance searches at LHC
Energy Technology Data Exchange (ETDEWEB)
Di Luzio, Luca [Universita di Genova, Dipartimento di Fisica, Genova (Italy); Durham University, Institute for Particle Physics Phenomenology, Department of Physics, Durham (United Kingdom); INFN, Sezione di Genova (Italy); Kamenik, Jernej F. [Jozef Stefan Institute, Ljubljana (Slovenia); University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana (Slovenia); Nardecchia, Marco [DAMTP, University of Cambridge, Cambridge (United Kingdom); CERN, Theoretical Physics Department, Geneva (Switzerland)
2017-01-15
We study the constraints implied by partial wave unitarity on new physics in the form of spin-zero di-boson resonances at LHC. We derive the scale where the effective description in terms of the SM supplemented by a single resonance is expected to break down depending on the resonance mass and signal cross section. Likewise, we use unitarity arguments in order to set perturbativity bounds on renormalizable UV completions of the effective description. We finally discuss under which conditions scalar di-boson resonance signals can be accommodated within weakly coupled models. (orig.)
Electroweak unification and tree unitarity
International Nuclear Information System (INIS)
Horejsi, J.
1993-01-01
The monograph is an unconventional introduction into the theory of unification of weak and electromagnetic interactions, which is conceptually different from the exposition presented in standard textbooks. A detailed explanation is given of the way to the standard model of electroweak interactions which is based on a straightforward application of the requirement of renormalizability of the perturbation series expansion. The procedure to derive the model is interesting as it demonstrates the necessity of introducing vector bosons and Yang-Mills type interactions and at least one elementary scalar boson to obtain a renormalizable theory of weak and electromagnetic interactions. The book is divided into 5 chapters: introduction, problems encountered in a Fermi type theory, the intermediate vector boson, electrodynamics of vector bosons, tree unitarity, and electroweak interactions. Each chapter is completed with exercise problems to be solved by the reader. The text is supplemented with a number of appendices. The monograph is aimed at undergraduate and postgraduate students as well as at physicists interested in the theory of elementary particles. (Z.J.)
Implications of unitarity and gauge invariance for simplified dark matter models
International Nuclear Information System (INIS)
Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Schwetz, Thomas; Vogl, Stefan
2016-01-01
We show that simplified models used to describe the interactions of dark matter with Standard Model particles do not in general respect gauge invariance and that perturbative unitarity may be violated in large regions of the parameter space. The modifications necessary to cure these inconsistencies may imply a much richer phenomenology and lead to stringent constraints on the model. We illustrate these observations by considering the simplified model of a fermionic dark matter particle and a vector mediator. Imposing gauge invariance then leads to strong constraints from dilepton resonance searches and electroweak precision tests. Furthermore, the new states required to restore perturbative unitarity can mix with Standard Model states and mediate interactions between the dark and the visible sector, leading to new experimental signatures such as invisible Higgs decays. The resulting constraints are typically stronger than the ‘classic’ constraints on DM simplified models such as monojet searches and make it difficult to avoid thermal overproduction of dark matter.
Implications of unitarity and gauge invariance for simplified dark matter models
International Nuclear Information System (INIS)
Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Schwetz, Thomas; Vogl, Stefan; Stockholm Univ.
2015-10-01
We show that simplified models used to describe the interactions of dark matter with Standard Model particles do not in general respect gauge invariance and that perturbative unitarity may be violated in large regions of the parameter space. The modifications necessary to cure these inconsistencies may imply a much richer phenomenology and lead to stringent constraints on the model. We illustrate these observations by considering the simplified model of a fermionic dark matter particle and a vector mediator. Imposing gauge invariance then leads to strong constraints from dilepton resonance searches and electroweak precision tests. Furthermore, the new states required to restore perturbative unitarity can mix with Standard Model states and mediate interactions between the dark and the visible sector, leading to new experimental signatures such as invisible Higgs decays. The resulting constraints are typically stronger than the 'classic' constraints on DM simplified models such as monojet searches and make it difficult to avoid thermal overproduction of dark matter.
Dynamics of unitarization by classicalization
International Nuclear Information System (INIS)
Dvali, Gia; Pirtskhalava, David
2011-01-01
We study dynamics of the classicalization phenomenon suggested in G. Dvali et al. , according to which a class of non-renormalizable theories self-unitarizes at very high-energies via creation of classical configurations (classicalons). We study this phenomenon in an explicit model of derivatively-self-coupled scalar that serves as a prototype for a Nambu-Goldstone-Stueckelberg field. We prepare the initial state in form of a collapsing wave-packet of a small occupation number but of very high energy, and observe that the classical configuration indeed develops. Our results confirm the previous estimates, showing that because of self-sourcing the wave-packet forms a classicalon configuration with radius that increases with center of mass energy. Thus, classicalization takes place before the waves get any chance of probing short-distances. The self-sourcing by energy is the crucial point, which makes classicalization phenomenon different from the ordinary dispersion of the wave-packets in other interacting theories. Thanks to this, unlike solitons or other non-perturbative objects, the production of classicalons is not only unsuppressed, but in fact dominates the high-energy scattering. In order to make the difference between classicalizing and non-classicalizing theories clear, we use a language in which the scattering cross section in a generic theory can be universally understood as a geometric cross section set by a classical radius down to which waves can propagate freely, before being scattered. We then show, that in non-classicalizing examples this radius shrinks with increasing energy and becomes microscopic, whereas in classicalizing theories expands and becomes macroscopic. We study analogous scattering in a Galileon system and discover that classicalization also takes place there, although somewhat differently. We thus observe, that classicalization is source-sensitive and that Goldstones pass the first test.
Matter scattering in quadratic gravity and unitarity
Abe, Yugo; Inami, Takeo; Izumi, Keisuke; Kitamura, Tomotaka
2018-03-01
We investigate the ultraviolet (UV) behavior of two-scalar elastic scattering with graviton exchanges in higher-curvature gravity theory. In Einstein gravity, matter scattering is shown not to satisfy the unitarity bound at tree level at high energy. Among some of the possible directions for the UV completion of Einstein gravity, such as string theory, modified gravity, and inclusion of high-mass/high-spin states, we take R_{μν}^2 gravity coupled to matter. We show that matter scattering with graviton interactions satisfies the unitarity bound at high energy, even with negative norm states due to the higher-order derivatives of metric components. The difference in the unitarity property of these two gravity theories is probably connected to that in another UV property, namely, the renormalizability property of the two.
Hunting for new physics with unitarity boomerangs
International Nuclear Information System (INIS)
Frampton, Paul H.; He Xiaogang
2010-01-01
The standard model of particle theory will be rigorously tested by upcoming precision data on flavor mixing. Although the unitarity triangles (UTs) carry information about the Kobayashi-Maskawa (KM) quark mixing matrix, it explicitly contains just three parameters which is one short to completely fix the KM matrix. We have recently shown that the unitarity boomerangs (UBs) formed using two UTs, with a common inner angle, can completely determine the KM matrix and, therefore, better represents quark mixing. Out of the total 18 possible UBs, there is only one that does not involve very small angles and is the ideal one for practical uses. Although the UBs have different areas, there is, however, an invariant quantity, for all UBs, which is equal to a quarter of the Jarlskog parameter J squared. Hunting for new physics, with a unitarity boomerang, can reveal more information, than just using a UTs.
Three-body unitarity with isobars revisited
Energy Technology Data Exchange (ETDEWEB)
Mai, M.; Hu, B. [The George Washington University, Washington, DC (United States); Doering, M. [The George Washington University, Washington, DC (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Pilloni, A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Szczepaniak, A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Indiana University, Center for Exploration of Energy and Matter, Bloomington, IN (United States); Indiana University, Physics Department, Bloomington, IN (United States)
2017-09-15
The particle exchange model of hadron interactions can be used to describe three-body scattering under the isobar assumption. In this study we start from the 3 → 3 scattering amplitude for spinless particles, which contains an isobar-spectator scattering amplitude. Using a Bethe-Salpeter Ansatz for the latter, we derive a relativistic three-dimensional scattering equation that manifestly fulfills three-body unitarity and two-body unitarity for the sub-amplitudes. This property holds for energies above breakup and also in the presence of resonances in the sub-amplitudes. (orig.)
Unitarity bounds on low scale quantum gravity
International Nuclear Information System (INIS)
Atkins, Michael; Calmet, Xavier
2010-01-01
We study the unitarity of models with low scale quantum gravity both in four dimensions and in models with a large extra-dimensional volume. We find that models with low scale quantum gravity have problems with unitarity below the scale at which gravity becomes strong. An important consequence of our work is that their first signal at the Large Hadron Collider would not be of a gravitational nature such as graviton emission or small black holes, but rather would be linked to the mechanism which fixes the unitarity problem. We also study models with scalar fields with non-minimal couplings to the Ricci scalar. We consider the strength of gravity in these models and study the consequences for inflation models with non-minimally coupled scalar fields. We show that a single scalar field with a large non-minimal coupling can lower the Planck mass in the TeV region. In that model, it is possible to lower the scale at which gravity becomes strong down to 14 TeV without violating unitarity below that scale. (orig.)
Harry Lehmann and the analyticity unitarity programme
International Nuclear Information System (INIS)
Martin, A.
2001-01-01
I try to describe the extremely fruitful interaction I had with Harry Lehmann and the results which came out of the analyticity unitarity programme, especially the proof of the Froissart bound, which, with recent and future measurements of total cross-sections and real parts, remains topical. (orig.)
Antishadowing effects in the unitarized BFKL equation
International Nuclear Information System (INIS)
Ruan Jianhong; Shen Zhenqi; Yang Jifeng; Zhu Wei
2007-01-01
A unitarized BFKL equation incorporating shadowing and antishadowing corrections of the gluon recombination is proposed. This equation reduces to the Balitsky-Kovchegov evolution equation near the saturation limit. We find that the antishadowing effects have a sizable influence on the gluon distribution function in the preasymptotic regime
Antishadowing effects in the unitarized BFKL equation
Energy Technology Data Exchange (ETDEWEB)
Ruan Jianhong [Department of Physics, East China Normal University, Shanghai 200062 (China); Shen Zhenqi [Department of Physics, East China Normal University, Shanghai 200062 (China); Yang Jifeng [Department of Physics, East China Normal University, Shanghai 200062 (China); Zhu Wei [Department of Physics, East China Normal University, Shanghai 200062 (China)]. E-mail: weizhu@mail.ecnu.edu.cn
2007-01-01
A unitarized BFKL equation incorporating shadowing and antishadowing corrections of the gluon recombination is proposed. This equation reduces to the Balitsky-Kovchegov evolution equation near the saturation limit. We find that the antishadowing effects have a sizable influence on the gluon distribution function in the preasymptotic regime.
Higgs-Palatini inflation and unitarity
International Nuclear Information System (INIS)
Bauer, Florian; Demir, Durmus A.
2011-01-01
In the Higgs inflation scenario the Higgs field is strongly coupled to the Ricci scalar in order to drive primordial inflation. However, in its original form in pure metric formulation of gravity, the ultraviolet (UV) cutoff of the Higgs interactions and the Hubble rate are of the same magnitude, and this makes the whole inflationary evolution dependent of the unknown UV completion of the Higgs sector. This problem, the unitarity violation, plagues the Higgs inflation scenario. In this Letter we show that, in the Palatini formulation of gravitation, Higgs inflation does not suffer from unitarity violation since the UV cutoff lies parametrically much higher than the Hubble rate so that unknown UV physics does not disrupt the inflationary dynamics. Higgs-Palatini inflation, as we call it, is, therefore, UV-safe, minimal and endowed with predictive power.
Black hole information, unitarity, and nonlocality
Giddings, Steven B.
2006-01-01
The black hole information paradox apparently indicates the need for a fundamentally new ingredient in physics. The leading contender is nonlocality. Possible mechanisms for the nonlocality needed to restore unitarity to black hole evolution are investigated. Suggestions that such dynamics arises from ultra-planckian modes in Hawking's derivation are investigated and found not to be relevant, in a picture using smooth slices spanning the exterior and interior of the horizon. However, no simul...
Workshop on the CKM Unitarity Triangle
Patrice Loïez
2002-01-01
The CKM Unitarity Triangle Workshop is meant to provide an opportunity for an intense and fruitful exchange of ideas between experimentalists and theorists to assess the present knowledge on fundamental parameters from the data of LEP and other colliders, to define an agenda of future measurements to further probe the model assumptions employed in the interpretation of the data and to indicate paths for the B physics programme at LHC.
Noncommutativity and unitarity violation in gauge boson scattering
International Nuclear Information System (INIS)
Hewett, J. L.; Petriello, F. J.; Rizzo, T. G.
2002-01-01
We examine the unitarity properties of spontaneously broken noncommutative gauge theories. We find that the symmetry breaking mechanism in the noncommutative standard model of Chaichian et al. leads to an unavoidable violation of tree-level unitarity in gauge boson scattering at high energies. We then study a variety of simplified spontaneously broken noncommutative theories and isolate the source of this unitarity violation. Given the group theoretic restrictions endemic to noncommutative model building, we conclude that it is difficult to build a noncommutative standard model under the Weyl-Moyal approach that preserves unitarity
Unitarity relations for the four-body scattering amplitude
International Nuclear Information System (INIS)
Matsui, Y.
1988-01-01
A formal derivation of the general unitarity relation for the four-particle transition operator is given by generalizing the three-body formalism of Karlson and Zeiger to the four-body case. From this operator relation the on-shell unitarity relations for the amplitudes that describe elastic/rearrangement, partial breakup, and full breakup scattering processes are obtained
Massive Yang-Mills theory: Renormalizability versus unitarity
International Nuclear Information System (INIS)
Delbourgo, R.; Twisk, S.; Thompson, G.
1987-06-01
Various massive Yang-Mills theories not based on the Higgs mechanism are investigated. They are subject to conflicting demands in the twin requirements of unitarity and perturbative renormalizability. Either one or other of these requirements is violated. Unitarity is considered in some detail. (author). 18 refs, 5 figs
Gauge theory high-energy behavior from j-plane unitarity
International Nuclear Information System (INIS)
Coriano, C.; Florida Univ., Gainesville, FL; White, A.R.
1996-01-01
In a non-abelian gauge theory the t-channel multiparticle unitarity equations continued in the complex j-plane can be systematically expanded around j=1 and t=0. The combination of Ward identity constraints with unitarity is sufficient to produce directly many of the results obtained by Regge limit leading-log and next-to-leading log momentum-space calculations. The O(g 2 ) BFKL kernel is completely determined. O(g 4 ) infrared contributions to this kernel are also obtained, including the leading contribution of a new partial-wave amplitude - previously identified as a separate forward component with a holomorphically factorizable spectrum. For this amplitude the only scale ambiguity is the overall normalization and it is anticipated to be a new conformally invariant kernel. While scale-dependent non-leading reggeon interactions can not be derived by the techniques developed, it is conjectured that all conformally invariant interactions may be determined by t-channel unitarity. (orig.)
The CKM matrix and the unitarity triangle
International Nuclear Information System (INIS)
Battaglia, M.; Buras, A.J.; Gambino, P.; Stocchi, A.; Abbaneo, D.; Ali, A.; Amaral, P.; Andreev, V.; Artuso, M.; Barberio, E.; Bauer, C.; Becirevic, D.; Beneke, M.; Bigi, I.; Bozzi, C.; Brandt, T.; Buchalla, G.; Calvi, M.; Cassel, D.; Cirigliano, V.; Ciuchini, M.
2003-01-01
This report contains the results of the Workshop on the CKM Unitarity Triangle that was held at CERN on 13-16 February 2002. There had been several Workshops on B physics that concentrated on studies at e + e - machines, at the Tevatron, or at LHC separately. Here we brought together experts of different fields, both theorists and experimentalists, to study the determination of the CKM matrix from all the available data of K, D, and B physics. The analysis of LEP data for B physics is reaching its end, and one of the goals of the Workshop was to underline the results that have been achieved at LEP, SLC, and CESR. Another goal was to prepare for the transfer of responsibility for averaging B physics properties, that has developed within the LEP community, to the present main actors of these studies, from the B factory and the Tevatron experiments. The optimal way to combine the various experimental and theoretical inputs and to fit for the apex of the Unitarity Triangle has been a contentious issue. A further goal of the Workshop was to bring together the proponents of different fitting strategies, and to compare their approaches when applied to the same inputs. Since lattice QCD plays a very important role in the determination of the non-perturbative parameters needed to constrain the CKM unitarity triangle, the first Workshop was seen as an excellent opportunity to bring together lattice theorists with the aim of establishing a working group to compile averages for phenomenologically relevant quantities. Representatives from lattice collaborations around the world were invited to attend a meeting during the Workshop. A consensus was reached to set up three test working groups, collectively known as the 'CKM Lattice Working Group', to review a number of well-studied quantities: quark masses, the kaon B-parameter, and the matrix elements relevant for neutral B-meson mixing. These proceedings are organized as a coherent document with chapters covering the domains of
The CKM Matrix and the unitarity triangle
International Nuclear Information System (INIS)
Battaglia, M.
2003-01-01
This report contains the results of the Workshop on the CKM Unitarity Triangle that was held at CERN on 13-16 February 2002. There had been several Workshops on B physics that concentrated on studies at e + e - machines, at the Tevatron, or at LHC separately. Here we brought together experts of different fields, both theorists and experimentalists, to study the determination of the CKM matrix from all the available data of K, D, and B physics. The analysis of LEP data for B physics is reaching its end, and one of the goals of the Workshop was to underline the results that have been achieved at LEP, SLC, and CESR. Another goal was to prepare for the transfer of responsibility for averaging B physics properties, that has developed within the LEP community, to the present main actors of these studies, from the B factory and the Tevatron experiments. The optimal way to combine the various experimental and theoretical inputs and to fit for the apex of the Unitarity Triangle has been a contentious issue. A further goal of the Workshop was to bring together the proponents of different fitting strategies, and to compare their approaches when applied to the same inputs. Since lattice QCD plays a very important role in the determination of the non-perturbative parameters needed to constrain the CKM unitarity triangle, the first Workshop was seen as an excellent opportunity to bring together lattice theorists with the aim of establishing a working group to compile averages for phenomenologically relevant quantities. Representatives from lattice collaborations around the world were invited to attend a meeting during the Workshop. A consensus was reached to set up three test working groups, collectively known as the ''CKM Lattice Working Group'', to review a number of well-studied quantities: quark masses, the kaon B-parameter, and the matrix elements relevant for neutral B-meson mixing. These proceedings are organized as a coherent document with chapters covering the domains
Dual unitarization scheme with several trajectories
International Nuclear Information System (INIS)
Chaichiam, M.; Hayashi, M.
1977-12-01
Consequences of bootstrap with several input Regge trajectories are investigated. We find that in a formal treatment of bootstrap the consistency requires the intercept of output Pomeron pole in the one-dimensional case to be larger than one: αsub(B)(0) > 1, a situation reminiscent of the one in the Reggeon field theory. Symmetry breakings of the Pomeron couplings are derived. These couplings coincide with those of the f-dominated Pomeron model of Carlitz-Green-Zee in the approximation, when in the unitarity loops only highest Regge trajectories are included. The case when all possible trajectories are exchanged is also discussed. Predictions of dual unitary model for the slopes of differential cross section for diffractive scattering are made which differ from the ones of the CGZ model. Comparison with the experimentally available data is done. (author)
Black hole information, unitarity, and nonlocality
International Nuclear Information System (INIS)
Giddings, Steven B.
2006-01-01
The black hole information paradox apparently indicates the need for a fundamentally new ingredient in physics. The leading contender is nonlocality. Possible mechanisms for the nonlocality needed to restore unitarity to black hole evolution are investigated. Suggestions that such dynamics arise from ultra-Planckian modes in Hawking's derivation are investigated and found not to be relevant, in a picture using smooth slices spanning the exterior and interior of the horizon. However, no simultaneous description of modes that have fallen into the black hole and outgoing Hawking modes can be given without appearance of a large kinematic invariant, or other dependence on ultra-Planckian physics. This indicates that a reliable argument for information loss has not been constructed, and that strong gravitational dynamics is important. Such dynamics has been argued to be fundamentally nonlocal in extreme situations, such as those required to investigate the fate of information
Unitarity and amplitudes for high energies
International Nuclear Information System (INIS)
Efimov, G.V.
1997-01-01
It is shown that in the quantum field theory of scalar particles with mass m the following inequalities for the upper bound for the amplitude of elastic scattering Μ(s,t) |Μ(s,t)| 0 )s, (|t|≥|t 0 |>0) and for the total cross section of scalar particles σ tot (s)≤C|d/dt ln Im Μ(s,t)| t=0 , (s → ∞) are valid. This result is based on the unitarity of the S-matrix on the mass shell and on a natural assumption that the imaginary part of the elastic scattering Im Μ(s,t) is a differentiable and convex down function in some vicinity of t=0. The locality of the theory and the analyticity of the elastic amplitude in the Martin-Lehmann ellipse are not used in proving these inequalities
Heavy-light fermion mixtures at unitarity
Energy Technology Data Exchange (ETDEWEB)
Gezerlis, Alexandros [Los Alamos National Laboratory; Carlson, Joseph [Los Alamos National Laboratory; Gandol, S [UNIV. ILL; Schmidt, E [ITALY
2009-01-01
We investigate fermion pairing in the unitary regime for a mass ratio corresponding to a {sup 6}Li-{sup 40}K mixture using quantum Monte Carlo methods. The ground-state energy and the average light- and heavy-particle excitation spectrum for the unpolarized superfluid state are nearly independent of the mass ratio. In the majority light system, the polarized superfluid is close to the energy of a phase separated mixture of nearly fully polarized normal and unpolarized superfluid. For a majority of heavy particles, we find an energy minimum for a normal state with a ratio of {approx}3:1 heavy to light particles. A slight increase in attraction to k{sub F}a{approx}2.5 yields a ground state energy of nearly zero for this ratio. A cold unpolarized system in a harmonic trap at unitarity should phase separate into three regions, with a shell of unpolarized superfluid in the middle.
A framework for testing leptonic unitarity by neutrino oscillation experiments
Energy Technology Data Exchange (ETDEWEB)
Fong, Chee Sheng [Instituto de Física, Universidade de São Paulo,C.P. 66.318, 05315-970 São Paulo (Brazil); Minakata, Hisakazu [Department of Physics, Yachay Tech,San Miguel de Urcuquí, 100119 (Ecuador); Nunokawa, Hiroshi [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro,C.P. 38097, 22451-900, Rio de Janeiro (Brazil)
2017-02-22
If leptonic unitarity is violated by new physics at an energy scale much lower than the electroweak scale, which we call low-scale unitarity violation, it has different characteristic features from those expected in unitarity violation at high-energy scales. They include maintaining flavor universality and absence of zero-distance flavor transition. We present a framework for testing such unitarity violation at low energies by neutrino oscillation experiments. Starting from the unitary 3 active plus N (arbitrary positive integer) sterile neutrino model we show that by restricting the active-sterile and sterile-sterile neutrino mass squared differences to ≳ 0.1 eV{sup 2} the oscillation probability in the (3+N) model becomes insensitive to details of the sterile sector, providing a nearly model-independent framework for testing low-scale unitarity violation. Yet, the presence of the sterile sector leaves trace as a constant probability leaking term, which distinguishes low-scale unitarity violation from the high-scale one. The non-unitary mixing matrix in the active neutrino subspace is common for the both cases. We analyze how severely the unitarity violation can be constrained in ν{sub e}-row by taking a JUNO-like setting to simulate medium baseline reactor experiments. Possible modification of the features of the (3+N) model due to matter effect is discussed to first order in the matter potential.
Signature of a Collaboration agreement between Unitar & CERN.
Pierre Gildemyn
2012-01-01
Signature of agreement with Mr Carlos Lopes (UNITAR) and Prof Rolf Heuer (CERN). From left to right : Einar Bjorgo, Francesco Pisano, Calors Lopes, Rolf Heuer, Maurizio Bona, Frédéric Hemmer, Olivier Van Damme
Unitarity violation in noninteger dimensional Gross-Neveu-Yukawa model
Ji, Yao; Kelly, Michael
2018-05-01
We construct an explicit example of unitarity violation in fermionic quantum field theories in noninteger dimensions. We study the two-point correlation function of four-fermion operators. We compute the one-loop anomalous dimensions of these operators in the Gross-Neveu-Yukawa model. We find that at one-loop order, the four-fermion operators split into three classes with one class having negative norms. This implies that the theory violates unitarity, following the definition in Ref. [1].
Unitarity and time reversal in the Glauber model
International Nuclear Information System (INIS)
Lazard, C.; Lombard, R.J.
1984-12-01
It has been pointed out by Formanek (1976-1980) that for incident energies above the particle production threshold the usual Glauber formulation of particle-nucleus scattering violates unitarity and time reversal invariance. We propose a simple method for recovering T-invariance and we discuss unitarity in view of the proposed modification. Numerical estimates are given to check the importance of T-invariance effects
The Okubo-Zweig-Iizuka rule and unitarity
International Nuclear Information System (INIS)
Ruuskanen, V.; Toernqvist, N.A.
1977-01-01
Using an explicitly unitary framework the Okubo-Zweig-Iizuka (OZI) rule is discussed and in particular how this rule is compatible with unitarity. For the phi-ω case unitarity effects (phi→KantiK→ω) contribute a (nearly) imaginary mixing of 0.6 +- 0.1 % and thus cannot account for the whole mixing of 6-10 %. For the f'-f mixing unitarity effects give a much larger value (>6.8%). In order to understand the small experimental f'→2π coupling the process f'→f→2π must be cancelled by another process e.g. f'→fsup((2))→2π, where fsup((2)) is a heavy f-like meson. For the psions above the first important charm threshold unitarity effects are likely to be crucial. At very high energies cancellations can suppress the unitarity effects. But in a transient energy interval (+p particular between the Dsup(*)antiDsup(*) and the Dsup(*)antiDsup(**) thresholds) these cancellations cannot work everywhere because mass differences are important. Therefore (if charm annihilation amplitudes near threshold are not negligibly small), it is expected that in this interval unitarity effects should be the dominant mechanism for the breaking of the OZI rule. Results from a conventional mass matrix mixing analysis are also given in the appendix. (author)
The Okubo-Zweig-Iizuka rule and dual unitarization
International Nuclear Information System (INIS)
Ninomiya, Kansuke; Toyoda, Fumihiko.
1978-01-01
The Okubo-Zweig-Iizuka (OZI) rule carries an important role in the constituent rearrangement and interest in the rule has been increased by the discovery of the J/psi particle. An example of phenomenological analysis related to the OZI rule is introduced. The decays of psi particles can be explained consistently by an existence of the disconnected type of a constituent rearrangement diagram (CRD) with comparable strength to that of the connected one. A survey of an outline of the dual unitarization scheme and discussion of the OZI rule with the scheme and other related theory are presented. The method of dual unitarization starts with the unitarity relation. In the estimation of multiparticle production amplitude in the unitarity sum, dominant nondiffractive production component is taken as a first approximation and the amplitude is described by the multiperipheral model of Reggeon exchange. Here, a case of meson-meson scattering in flavor of SU(N) scheme is considered. A survey of the mechanism of the planar bootstrap and Pomeron generation in the dual unitarization is made. The nonplanar CR diagrams give breaking of various features at the planar level. The reaction with the disconnected CRD could occur in the nonperipheral region through the hard collision of constituent and appears at large momentum transfers in comparable order with a connected one. Baryon and baryoniums with the scheme of the dual unitarization are examined. (Kato, T.)
Unitarity problems in 3D gravity theories
Alkac, Gokhan; Basanisi, Luca; Kilicarslan, Ercan; Tekin, Bayram
2017-07-01
We revisit the problem of the bulk-boundary unitarity clash in 2 +1 -dimensional gravity theories, which has been an obstacle in providing a viable dual two-dimensional conformal field theory for bulk gravity in anti-de Sitter (AdS) spacetime. Chiral gravity, which is a particular limit of cosmological topologically massive gravity (TMG), suffers from perturbative log-modes with negative energies inducing a nonunitary logarithmic boundary field theory. We show here that any f (R ) extension of TMG does not improve the situation. We also study the perturbative modes in the metric formulation of minimal massive gravity—originally constructed in a first-order formulation—and find that the massive mode has again negative energy except in the chiral limit. We comment on this issue and also discuss a possible solution to the problem of negative-energy modes. In any of these theories, the infinitesimal dangerous deformations might not be integrable to full solutions; this suggests a linearization instability of AdS spacetime in the direction of the perturbative log-modes.
Next-to-leading order unitarity fits in Two-Higgs-Doublet models with soft ℤ{sub 2} breaking
Energy Technology Data Exchange (ETDEWEB)
Cacchio, Vincenzo; Chowdhury, Debtosh; Eberhardt, Otto [Istituto Nazionale di Fisica Nucleare, Sezione di Roma,Piazzale Aldo Moro 2, I-00185 Roma (Italy); Murphy, Christopher W. [Scuola Normale Superiore,Piazza dei Cavalieri 7, I-56126 Pisa (Italy)
2016-11-07
We fit the next-to-leading order unitarity conditions to the Two-Higgs-Doublet model with a softly broken ℤ{sub 2} symmetry. In doing so, we alleviate the existing uncertainty on how to treat higher order corrections to quartic couplings of its Higgs potential. A simplified approach to implementing the next-to-leading order unitarity conditions is presented. These new bounds are then combined with all other relevant constraints, including the complete set of LHC Run I data. The upper 95% bounds we find are 4.2 on the absolute values of the quartic couplings, and 235 GeV (100 GeV) for the mass degeneracies between the heavy Higgs particles in the type I (type II) scenario. In type II, we exclude an unbroken ℤ{sub 2} symmetry with a probability of 95%. All fits are performed using the open-source code HEPfit.
Unitarity boomerangs of quark and lepton mixing matrices
International Nuclear Information System (INIS)
Li Shiwen; Ma Boqiang
2010-01-01
The most popular way to present mixing matrices of quarks (CKM) and leptons (PMNS) is the parametrization with three mixing angles and one CP-violating phase. There are two major options in this kind of parametrizations, one is the original Kobayashi-Maskawa (KM) matrix, and the other is the Chau-Keung (CK) matrix. In a new proposal by Frampton and He, a unitarity boomerang is introduced to combine two unitarity triangles, and this new presentation displays all four independent parameters of the KM parametrization in the quark sector simultaneously. In this Letter, we study the relations between KM and CK parametrizations, and also consider the quark-lepton complementarity (QLC) in the KM parametrization. The unitarity boomerang is discussed in the situation of the CK parametrization for comparison with that in the KM parametrization in the quark sector. Then we extend the idea of unitarity boomerang to the lepton sector, and check the corresponding unitarity boomerangs in the two cases of parametrizations.
Unitarity boomerangs of quark and lepton mixing matrices
Energy Technology Data Exchange (ETDEWEB)
Li Shiwen [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Ma Boqiang, E-mail: mabq@phy.pku.edu.c [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Center for High Energy Physics, Peking University, Beijing 100871 (China)
2010-07-12
The most popular way to present mixing matrices of quarks (CKM) and leptons (PMNS) is the parametrization with three mixing angles and one CP-violating phase. There are two major options in this kind of parametrizations, one is the original Kobayashi-Maskawa (KM) matrix, and the other is the Chau-Keung (CK) matrix. In a new proposal by Frampton and He, a unitarity boomerang is introduced to combine two unitarity triangles, and this new presentation displays all four independent parameters of the KM parametrization in the quark sector simultaneously. In this Letter, we study the relations between KM and CK parametrizations, and also consider the quark-lepton complementarity (QLC) in the KM parametrization. The unitarity boomerang is discussed in the situation of the CK parametrization for comparison with that in the KM parametrization in the quark sector. Then we extend the idea of unitarity boomerang to the lepton sector, and check the corresponding unitarity boomerangs in the two cases of parametrizations.
On unitarity of the particle-hole dispersive optical model
Gorelik, M. L.; Shlomo, S.; Tulupov, B. A.; Urin, M. H.
2018-02-01
For the recently developed particle-hole dispersive optical model, weak violations of unitarity due to a phenomenological description of the spreading effect are considered. Methods for unitarity restoration are proposed and implemented for the 208Pb nucleus in the description of the energy-averaged isoscalar monopole double transition density and strength functions in a wide excitation energy interval that includes the isoscalar giant monopole resonance and its overtone. To illustrate abilities of the model, direct neutron decay of the mentioned giant resonance is also considered.
Unitarity, (anti)shadowing, and black-disk limit
International Nuclear Information System (INIS)
Desgrolard, P.; Jenkovszky, L.; Struminsky, B.V.
2000-01-01
By using realistic models for elastic hadron scattering, we demonstrate that, at current accelerator energies, the s-channel unitarity bound is safe and is not to be reached until 10 5 GeV, while the black-disk limit is saturated around 6 TeV. It will be followed by a larger transparency of the scattered particles near the center
Electroweak symmetry breaking: Unitarity, dynamics, and experimental prospects
International Nuclear Information System (INIS)
Chanowitz, M.S.
1988-01-01
A review of what is known about the unexplained mechanism that breaks the electroweak symmetry and thereby gives mass to the W and Z gauge bosons while leaving the photon massless is given. Symmetry, unitarity, technicolor, supersymmetry, higgs sector dynamics, and experimental status and prospects are discussed
Unitarity corrections to short-range order long-range rapidity correlations
Capella, A
1978-01-01
Although the effective hadronic forces have short range in rapidity space, one nevertheless expects long-range dynamical correlations induced by unitarity constraints. This paper contains a thorough discussion of long-range rapidity correlations in high-multiplicity events. In particular, the authors analyze in detail the forward- backward multiplicity correlations, measured recently in the whole CERN ISR energy range. They find from these data that the normalized variance of the number n of exchanged cut Pomerons, ((n/(n)-1)/sup 2/) , is most probably in the range 0.32 to 0.36. They show that such a number is obtained from Reggeon theory in the eikonal approximation. The authors also predict a very specific violation of local compensation of charge in multiparticle events: The violation should appear in the fourth-order zone correlation function and is absent in the second-order correlation function, the only one measured until now. (48 refs).
Standard Model updates and new physics analysis with the Unitarity Triangle fit
International Nuclear Information System (INIS)
Bevan, A.; Bona, M.; Ciuchini, M.; Derkach, D.; Franco, E.; Silvestrini, L.; Lubicz, V.; Tarantino, C.; Martinelli, G.; Parodi, F.; Schiavi, C.; Pierini, M.; Sordini, V.; Stocchi, A.; Vagnoni, V.
2013-01-01
We present the summer 2012 update of the Unitarity Triangle (UT) analysis performed by the UTfit Collaboration within the Standard Model (SM) and beyond. The increased accuracy on several of the fundamental constraints is now enhancing some of the tensions amongst and within the constraint themselves. In particular, the long standing tension between exclusive and inclusive determinations of the V ub and V cb CKM matrix elements is now playing a major role. Then we present the generalisation the UT analysis to investigate new physics (NP) effects, updating the constraints on NP contributions to ΔF=2 processes. In the NP analysis, both CKM and NP parameters are fitted simultaneously to obtain the possible NP effects in any specific sector. Finally, based on the NP constraints, we derive upper bounds on the coefficients of the most general ΔF=2 effective Hamiltonian. These upper bounds can be translated into lower bounds on the scale of NP that contributes to these low-energy effective interactions
Fermionic ground state at unitarity and Haldane exclusion statistics
Energy Technology Data Exchange (ETDEWEB)
Bhaduri, R K; Murthy, M V N [Institute of Mathematical Sciences, Chennai 600 113 (India); Brack, M [Institute for Theoretical Physics, University of Regensburg, Regensburg (Germany)
2008-06-14
We consider a few-particle system of trapped neutral fermionic atoms at ultra-low temperatures, with the attractive interaction tuned to Feshbach resonance. We calculate the energies and the spatial densities of the few-body systems using a generalization of the extended Thomas-Fermi (ETF) method, and assuming the particles obey the Haldane-Wu fractional exclusion statistics (FES) at unitarity. This method is different from the scaled ETF version given by Chang and Bertsch (2007 Phys. Rev. A 76 021603). Our semiclassical FES results are consistent with the Monte Carlo calculations of the above authors, but can hardly be distinguished from their overall scaling of the ETF result at unitarity.
Fermionic ground state at unitarity and Haldane exclusion statistics
International Nuclear Information System (INIS)
Bhaduri, R K; Murthy, M V N; Brack, M
2008-01-01
We consider a few-particle system of trapped neutral fermionic atoms at ultra-low temperatures, with the attractive interaction tuned to Feshbach resonance. We calculate the energies and the spatial densities of the few-body systems using a generalization of the extended Thomas-Fermi (ETF) method, and assuming the particles obey the Haldane-Wu fractional exclusion statistics (FES) at unitarity. This method is different from the scaled ETF version given by Chang and Bertsch (2007 Phys. Rev. A 76 021603). Our semiclassical FES results are consistent with the Monte Carlo calculations of the above authors, but can hardly be distinguished from their overall scaling of the ETF result at unitarity
Unitarity in three-dimensional flat space higher spin theories
International Nuclear Information System (INIS)
Grumiller, D.; Riegler, M.; Rosseel, J.
2014-01-01
We investigate generic flat-space higher spin theories in three dimensions and find a no-go result, given certain assumptions that we spell out. Namely, it is only possible to have at most two out of the following three properties: unitarity, flat space, non-trivial higher spin states. Interestingly, unitarity provides an (algebra-dependent) upper bound on the central charge, like c=42 for the Galilean W_4"("2"−"1"−"1") algebra. We extend this no-go result to rule out unitary “multi-graviton” theories in flat space. We also provide an example circumventing the no-go result: Vasiliev-type flat space higher spin theory based on hs(1) can be unitary and simultaneously allow for non-trivial higher-spin states in the dual field theory.
Meson-baryon interactions in unitarized chiral perturbation theory
International Nuclear Information System (INIS)
Garcia Recio, G.; Nieves, J.; Ruiz Arriola, E.; Vicente Vacas, M.
2003-01-01
Meson-Baryon Interactions can be successfully described using both Chiral Symmetry and Unitarity. The s-wave meson-baryon scattering amplitude is analyzed in a Bethe-Salpeter coupled channel formalism incorporating Chiral Symmetry in the potential. Two body coupled channel unitarity is exactly preserved. The needed two particle irreducible matrix amplitude is taken from lowest order Chiral Perturbation Theory in a relativistic formalism. Off-shell behavior is parameterized in terms of low energy constants. The relation to the heavy baryon limit is discussed. The position of the complex poles in the second Riemann sheet of the scattering amplitude determine masses and widths baryonic resonances of the N(1535), N(1670), Λ(1405) and Λ(1670) resonances which compare well with accepted numbers
Effective field theory and unitarity in vector boson scattering
International Nuclear Information System (INIS)
Sekulla, Marco; Kilian, Wolfgang; Ohl, Thorsten; Reuter, Juergen
2016-10-01
Weak vector boson scattering at high energies will be one of the key measurements in current and upcoming LHC runs. It is most sensitive to any new physics associated with electroweak symmetry breaking. However, a conventional EFT analysis will fail at high energies. To address this problem, we present a parameter-free prescription valid for arbitrary perturbative and non-perturbative models: the T-matrix unitarization. We describe its implementation as an asymptotically consistent reference model matched to the low-energy effective theory. We show examples of typical observables of vector-boson scattering at the LHC in our unitarized framework. For many strongly-coupled models like composite Higgs models, dimension-8 operators might be actually the leading operators. In addition to those longitudinal and transversal dimension eight EFT operators, the effects of generic tensor and scalar resonances within simplified models are considered.
Unitarity and the time evolution of quantum mechanical states
International Nuclear Information System (INIS)
Kabir, P.K.; Pilaftsis, A.
1996-01-01
The basic requirement that, in quantum theory, the time evolution of any state is determined by the action of a unitary operator, is shown to be the underlying cause for certain open-quote open-quote exact close-quote close-quote results that have recently been reported about the time dependence of transition rates in quantum theory. Departures from exponential decay, including the open-quote open-quote quantum Zeno effect,close-quote close-quote as well as a theorem by Khalfin about the ratio of reciprocal transition rates, are shown to follow directly from such considerations. At sufficiently short times, unitarity requires that reciprocity must hold, independent of whether T invariance is valid. If T invariance does not hold, unitarity restricts the form of possible time dependence of reciprocity ratios. copyright 1996 The American Physical Society
Swain, John; Taylor, Lucas
1997-01-01
The magnitudes of the CKM matrix elements $V_{td}$, $V_{ts}$, and $V_{tb}$ are determined for the first time without any assumptions of unitarity. The implications for the unitarity of the CKM matrix as a whole are discussed.
Reggeon, Pomeron and annihilation processes in the dual unitarization scheme
International Nuclear Information System (INIS)
Dias de Deus, J.
1976-07-01
In the framework of the dual unitarization scheme the connection between particle production in processes dominated by Reggeon, Pomeron and Annihilation diagrams is discussed and critical tests of the scheme are suggested. The simple relation for average multiplicities anti nsup(R) = 1/2 anti nsup(P) = 1/3 anti nsup(A) and other relations for inclusive cross-sections and higher moments of the particle distribution are shown to be in reasonable agreement with data. (author)
Loop Amplitudes in Pure Yang-Mills from Generalised Unitarity
Brandhuber, Andreas; McNamara, Simon; Spence, Bill; Travaglini, Gabriele
2005-01-01
We show how generalised unitarity cuts in D = 4 - 2 epsilon dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions.
Loop amplitudes in pure Yang-Mills from generalised unitarity
International Nuclear Information System (INIS)
Brandhuber, Andreas; McNamara, Simon; Spence, Bill; Travaglini, Gabriele
2005-01-01
We show how generalised unitarity cuts in D = 4-2ε dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions
Loop amplitudes in pure Yang-Mills from generalised unitarity
Energy Technology Data Exchange (ETDEWEB)
Brandhuber, Andreas [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); McNamara, Simon [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); Spence, Bill [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); Travaglini, Gabriele [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom)
2005-10-15
We show how generalised unitarity cuts in D = 4-2{epsilon} dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions.
Unitarization of pomeron and Regge phenomenology of deep inelastic scattering.
Energy Technology Data Exchange (ETDEWEB)
Martynov, E S
1994-12-31
Using conventional Regge approach we consider unitarization of supercritical pomeron in DIS and then describe the total photon-proton cross-section and the proton structure functions in the region W{sup 2} = Q{sup 2}(1/x-1) + m{sup 2} {>=} 9 GeV{sup 2}, including the small-x data from HERA. (author). 15 refs., 1 tab., 15 figs.
Quark-parton model from dual topological unitarization
International Nuclear Information System (INIS)
Cohen-Tannoudji, G.; El Hassouni, A.; Kalinowski, J.; Peschanski, R.
1979-01-01
Topology, which occurs in the topological expansion of quantum chromodynamics (QCD) and in the dual topological unitarization (DTU) schemes, allows us to establish a quantitative correspondence between QCD and the dual S-matrix approaches. This topological correspondence, proposed by Veneziano and made more explicit in a recent paper for current-induced reactions, provides a clarifying and unifying quark-parton interpretation of soft inclusive processes. Precise predictions for inclusive cross sections in hadron-hadron collisions, structure functions of hadrons, and quark fragmentation functions including absolute normalizations are shown to agree with data. On a more theoretical ground the proposed scheme suggests a new approach to the confinement problem
Thermal relic dark matter beyond the unitarity limit
Energy Technology Data Exchange (ETDEWEB)
Harigaya, Keisuke [Berkeley Center for Theoretical Physics, Department of Physics, University of California,Berkeley, CA 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, CA 94720 (United States); Ibe, Masahiro [Kavli IPMU (WPI), UTIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); ICRR, The University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Kaneta, Kunio [Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS),Daejeon 34051 (Korea, Republic of); Nakano, Wakutaka; Suzuki, Motoo [Kavli IPMU (WPI), UTIAS, The University of Tokyo,Kashiwa, Chiba 277-8583 (Japan); ICRR, The University of Tokyo,Kashiwa, Chiba 277-8582 (Japan)
2016-08-25
We discuss a simple model of thermal relic dark matter whose mass can be much larger than the so-called unitarity limit on the mass of point-like particle dark matter. The model consists of new strong dynamics with one flavor of fermions in the fundamental representation which is much heavier than the dynamical scale of the new strong dynamics. Dark matter is identified with the lightest baryonic hadron of the new dynamics. The baryonic hadrons annihilate into the mesonic hadrons of the new strong dynamics when they have large radii. Resultantly, thermal relic dark matter with a mass in the PeV range is possible.
Unitarity bounds on angular distribution in multiparticle production - II
International Nuclear Information System (INIS)
Divakaran, P.P.; Kugler, M.; Soffer, J.
1976-01-01
Upper bounds which follow from unitarity are derived for the angular distribution of the detected particle C in the inclusive process AB→C+anything at a finite energy, in terms of the corresponding elastic amplitudes for a fixed value of the forward inelastic cross-section and for a fixed value of the total inelastic cross-section for the production of C. In comparison with the pp→p+anything data at 24GeV/c, some improvement on previous bounds is observed [fr
Unitarity corrections to current algebra versus chiral perturbation calculations
International Nuclear Information System (INIS)
Sa Borges, J.
1991-01-01
We compare the result of the application of the chiral perturbation approach for pion-pion scattering amplitudes with the description that follows from our first order quasi-unitarized current algebra method. We show that the only discrepancy comes in the polynomial part of the amplitudes and we trace back its origin. We discuss the peculiarities of each model irrespective of their abilities to fit the low energy experimental data. We have extended our analysis to the possible parametrization of the unknown symmetry breaking dynamics of the standard model. (orig.)
Elastic unitarity of direct channel and Froissart saturation
International Nuclear Information System (INIS)
Glushko, N.I.; Kobylinsky, N.A.
1982-01-01
The condition of elastic unitarity for direct channel continued analytically to high-energy range reveals a fast (upper the Froissart bound) rise of the amplitude between elastic and inelastic cuts in the case when the hadron scattering picture approaches the black disc limit. This fact is assumed as a basis for a new model of generating the Froissart saturation which describes well the main characteristics of NN, PIN and KN scattering. The model suggested is also compared witn the U-matrix approach
Unitarity condition in covariant quantum field theory with indefinite metric
International Nuclear Information System (INIS)
Slavnov, A.A.
1989-01-01
Conditions that ensure the existence of a unitarity S matrix acting on the subspace of states with positive norm are formulated. A study is made of BRST quantization. The only restriction on the class of theories is that the author assumes asymptotic linearization of the theory, namely, that the asymptotic dynamics is determined by a quadratic Hamiltonian. In field theory this is always the case in the framework of standard perturbation theory. However, in some models, for example, string models, and also outside the framework of perturbation theory, this condition need not be satisfied
Generalized unitarity for N=4 super-amplitudes
Energy Technology Data Exchange (ETDEWEB)
Drummond, J.M.; Henn, J. [LAPTH, Université de Savoie, CNRS B.P. 110, F-74941 Annecy-le-Vieux Cedex (France); Korchemsky, G.P., E-mail: Gregory.Korchemsky@cea.fr [Institut de Physique Théorique, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Sokatchev, E. [LAPTH, Université de Savoie, CNRS B.P. 110, F-74941 Annecy-le-Vieux Cedex (France)
2013-04-21
We develop a manifestly supersymmetric version of the generalized unitarity cut method for calculating scattering amplitudes in N=4 SYM theory. We illustrate the power of this method by computing the one-loop n-point NMHV super-amplitudes. The result confirms two conjectures which we made in Drummond, et al., [1]. Firstly, we derive the compact, manifestly dual superconformally covariant form of the NMHV tree amplitudes for arbitrary number and types of external particles. Secondly, we show that the ratio of the one-loop NMHV to the MHV amplitude is dual conformal invariant.
Three-body unitarity in the finite volume
Energy Technology Data Exchange (ETDEWEB)
Mai, M. [The George Washington University, Washington, DC (United States); Doering, M. [The George Washington University, Washington, DC (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
2017-12-15
The physical interpretation of lattice QCD simulations, performed in a small volume, requires an extrapolation to the infinite volume. A method is proposed to perform such an extrapolation for three interacting particles at energies above threshold. For this, a recently formulated relativistic 3 → 3 amplitude based on the isobar formulation is adapted to the finite volume. The guiding principle is two- and three-body unitarity that imposes the imaginary parts of the amplitude in the infinite volume. In turn, these imaginary parts dictate the leading power-law finite-volume effects. It is demonstrated that finite-volume poles arising from the singular interaction, from the external two-body sub-amplitudes, and from the disconnected topology cancel exactly leaving only the genuine three-body eigenvalues. The corresponding quantization condition is derived for the case of three identical scalar-isoscalar particles and its numerical implementation is demonstrated. (orig.)
Cold atoms at unitarity and inverse square interaction
Energy Technology Data Exchange (ETDEWEB)
Bhaduri, R K [Department of Physics and Astronomy, McMaster University, Hamilton L8S 4M1 (Canada); Murthy, M V N [The Institute of Mathematical Sciences, Chennai 600113 (India); Srivastava, M K [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India)
2009-12-14
Consider two identical atoms in a spherical harmonic oscillator interacting with a zero-range interaction which is tuned to produce an s-wave zero-energy bound state. The quantum spectrum of the system is known to be exactly solvable. We note that the same partial wave quantum spectrum is obtained by the one-dimensional scale-invariant inverse square potential. Long known as the Calogero-Sutherland-Moser (CSM) model, it leads to the fractional exclusion statistics (FES) of Haldane and Wu. The statistical parameter is deduced from the analytically calculated second virial coefficient. When FES is applied to a Fermi gas at unitarity, it gives good agreement with experimental data without the use of any free parameter.
Can the "standard" unitarized Regge models describe the TOTEM data?
Alkin, A; Martynov, E
2013-01-01
The standard Regge poles are considered as inputs for two unitarization methods: eikonal and U-matrix. It is shown that only models with three input pomerons and two input odderons can describe the high energy data on $pp$ and $\\bar pp$ elastic scattering including the new data from Tevatron and LHC. However, it seems that the both considered models require a further modification (e.g. nonlinear reggeon trajectories and/or nonexponential vertex functions) for a more satisfactory description of the data at 19.0 GeV$\\leq \\sqrt{s}\\leq$ 7 TeV and 0.01 $\\leq |t|\\leq $14.2 GeV$^{2}$.
Hawking radiation, the Stefan–Boltzmann law, and unitarization
Energy Technology Data Exchange (ETDEWEB)
Giddings, Steven B., E-mail: giddings@physics.ucsb.edu
2016-03-10
Where does Hawking radiation originate? A common picture is that it arises from excitations very near or at the horizon, and this viewpoint has supported the “firewall” argument and arguments for a key role for the UV-dependent entanglement entropy in describing the quantum mechanics of black holes. However, closer investigation of both the total emission rate and the stress tensor of Hawking radiation supports the statement that its source is a near-horizon quantum region, or “atmosphere,” whose radial extent is set by the horizon radius scale. This is potentially important, since Hawking radiation needs to be modified to restore unitarity, and a natural assumption is that the scales relevant to such modifications are comparable to those governing the Hawking radiation. Moreover, related discussion suggests a resolution to questions regarding extra energy flux in “nonviolent” scenarios, that does not spoil black hole thermodynamics as governed by the Bekenstein–Hawking entropy.
Hawking radiation, the Stefan–Boltzmann law, and unitarization
International Nuclear Information System (INIS)
Giddings, Steven B.
2016-01-01
Where does Hawking radiation originate? A common picture is that it arises from excitations very near or at the horizon, and this viewpoint has supported the “firewall” argument and arguments for a key role for the UV-dependent entanglement entropy in describing the quantum mechanics of black holes. However, closer investigation of both the total emission rate and the stress tensor of Hawking radiation supports the statement that its source is a near-horizon quantum region, or “atmosphere,” whose radial extent is set by the horizon radius scale. This is potentially important, since Hawking radiation needs to be modified to restore unitarity, and a natural assumption is that the scales relevant to such modifications are comparable to those governing the Hawking radiation. Moreover, related discussion suggests a resolution to questions regarding extra energy flux in “nonviolent” scenarios, that does not spoil black hole thermodynamics as governed by the Bekenstein–Hawking entropy.
9th International Workshop on the CKM Unitarity Triangle
CKM2016
2016-01-01
The 9th International Workshop on the CKM Unitarity Triangle (CKM 2016) will be held during November 28 to December 3, 2016 at the Tata Institute of Fundamental Research in Mumbai, India. The CKM series is a well-established international meeting in the field of quark-flavour physics that brings both experimenters and theorists on a common platform. On the experimental front, we bridge borders between neutron, kaon, charm and beauty hadron, and top quark physics. The theory program tries to cover a wide range of approaches. We shall discuss how this marriage of the two can indirectly probe physics beyond the standard model, taking into account the interplay with high-pT collider searches.
Anomalous couplings, resonances and unitarity in vector boson scattering
Energy Technology Data Exchange (ETDEWEB)
Sekulla, Marco
2015-12-04
The Standard Model of particle physics has proved itself as a reliable theory to describe interactions of elementary particles. However, many questions concerning the Higgs sector and the associated electroweak symmetry breaking are still open, even after (or because) a light Higgs boson has been discovered. The 2→2 scattering amplitude of weak vector bosons is suppressed in the Standard Model due to the Higgs boson exchange. Therefore, weak vector boson scattering processes are very sensitive to additional contributions beyond the Standard Model. Possible new physics deviations can be studied model-independently by higher dimensional operators within the effective field theory framework. In this thesis, a complete set of dimension six and eight operators are discussed for vector boson scattering processes. Assuming a scenario where new physics in the Higgs/Goldstone boson decouples from the fermion-sector and the gauge-sector in the high energy limit, the impact of the dimension six operator L{sub HD} and dimension eight operators L{sub S,0} and L{sub S,1} to vector boson scattering processes can be studied separately for complete processes at particle colliders. However, a conventional effective field theory analysis will violate the S-matrix unitarity above a certain energy limit. The direct T-matrix scheme is developed to allow a study of effective field theory operators consistent with basic quantum-mechanical principles in the complete energy reach of current and future colliders. Additionally, this scheme can be used preventively for any model, because it leaves theoretical predictions invariant, which already satisfies unitarity. The effective field theory approach is further extended by allowing additional generic resonances coupling to the Higgs/Goldstone boson sector, namely the isoscalar-scalar, isoscalar-tensor, isotensor-scalar and isotensor-tensor. In particular, the Stueckelberg formalism is used to investigate the impact of the tensor degree of
On unitarity in renormalisable R2sub(μν) quantum gravity
International Nuclear Information System (INIS)
Tomboulis, E.T.
1987-01-01
The paper on unitarity in renormalisable quantum gravity is a contribution to the book commemorating the sixtieth birthday of E.S. Fradkin. Arguments are presented for the unitarity of the general fourth-order action (non-supersymmetric) of the renormalisable higher derivative theories of gravity directly in the continuum. Graviton propagators, propagator poles, massless matter fields and gauge theories are all discussed. (U.K.)
Kiefer, Claus; Wichmann, David
2018-06-01
We extend the Born-Oppenheimer type of approximation scheme for the Wheeler-DeWitt equation of canonical quantum gravity to arbitrary orders in the inverse Planck mass squared. We discuss in detail the origin of unitarity violation in this scheme and show that unitarity can be restored by an appropriate modification which requires back reaction from matter onto the gravitational sector. In our analysis, we heavily rely on the gauge aspects of the standard Born-Oppenheimer scheme in molecular physics.
Unitarity corrections in the pT distribution for the Drell-Yan process
International Nuclear Information System (INIS)
Betempts, M.A.; Gay Ducaty, M.B.; Machado, M.V.T.
2001-01-01
In this contribution we investigate the Drell-Yan transverse momentum distribution considering the color dipole approach, taking into account unitarity aspects in the dipole cross section. The process is analyzed in the current energies on pp collisions (√s = 62 GeV) and at LHC energies (√s = 8.8 TeV. The unitarity corrections are implemented through the multiple scattering Glauber-Mueller approach. (author)
Unitarity, Feedback, Interactions - Dynamics Emergent from Repeated Measurements
Corona Ugalde, Paulina; Altamirano, Natacha; Mann, Robert; Zych, Magdalena
Modern measurement theory dispenses with the description of a measurement as a projection. Rather, the measurement is understood as an operation, whereby the system's final state is determined by an action of a completely positive trace non-increasing map and the outcomes are described by linear operators on the system, distributed according to a positive-operator valued measure (POVM). The POVM approach unifies the theory of measurements with a general description of dynamics, the theory of open quantum systems. Engineering a particular measurement and engineering a particular dynamics for the system are thus two complementary aspects of the same conceptual framework. This correspondence is directly applied in quantum simulations and quantum control theory . With this motivation, we study what types of dynamics can emerge from a model of repeated short interactions of a system with a set of ancillae. We show that contingent on the model parameters the resulting dynamics ranges from exact unitarity to arbitrary fast decoherence. For a series of measurements the effective dynamics includes feedback-control, which for a composite system yields effective interactions between the subsystems. We quantify the amount of decoherence accompanying such induced interactions. The simple framework used in the present study can find applications in devising novel quantum control protocols, or quantum simulations.
Hawking radiation, the Stefan–Boltzmann law, and unitarization
Directory of Open Access Journals (Sweden)
Steven B. Giddings
2016-03-01
Full Text Available Where does Hawking radiation originate? A common picture is that it arises from excitations very near or at the horizon, and this viewpoint has supported the “firewall” argument and arguments for a key role for the UV-dependent entanglement entropy in describing the quantum mechanics of black holes. However, closer investigation of both the total emission rate and the stress tensor of Hawking radiation supports the statement that its source is a near-horizon quantum region, or “atmosphere,” whose radial extent is set by the horizon radius scale. This is potentially important, since Hawking radiation needs to be modified to restore unitarity, and a natural assumption is that the scales relevant to such modifications are comparable to those governing the Hawking radiation. Moreover, related discussion suggests a resolution to questions regarding extra energy flux in “nonviolent” scenarios, that does not spoil black hole thermodynamics as governed by the Bekenstein–Hawking entropy.
S-Channel Dark Matter Simplified Models and Unitarity
Englert, Christoph; Spannowsky, Michael
The ultraviolet structure of $s$-channel mediator dark matter simplified models at hadron colliders is considered. In terms of commonly studied $s$-channel mediator simplified models it is argued that at arbitrarily high energies the perturbative description of dark matter production in high energy scattering at hadron colliders will break down in a number of cases. This is analogous to the well documented breakdown of an EFT description of dark matter collider production. With this in mind, to diagnose whether or not the use of simplified models at the LHC is valid, perturbative unitarity of the scattering amplitude in the processes relevant to LHC dark matter searches is studied. The results are as one would expect: at the LHC and future proton colliders the simplified model descriptions of dark matter production are in general valid. As a result of the general discussion, a simple new class of previously unconsidered `Fermiophobic Scalar' simplified models is proposed, in which a scalar mediator couples to...
Contributions of unitarity diagrams to the polarization of fermions
International Nuclear Information System (INIS)
Quadder, B.
1992-01-01
In this work the subject of large single spin observables of fermions is addressed. Such observables, as for instance the analyzing power in elastic proton scattering or the polarization of hyperons, are related to the imaginary part of a product of spin-flip and non-flip amplitudes. So both spin-flip and relative phases between spin-flip and non-flip amplitudes are required to achieve non-vanishing single spin asymmetries. In the framework of perturbative Quantum Chromodynamics the asymmetry arises from the subprocess level. For massless quarks no spin-flips occur, because the coupling to spin 1-gluons conserves helicity. If the quarks are massive or particles with other spin than 1/2 are considered, the helicity conservation no longer holds. The born amplitudes are real, so the phases come from the second order box diagrams. An efficient method due to Charap and Leader to calculate the imaginary part of such unitarity diagrams is investigated. With the aid of the general unitary condition for particles with arbitrary spins the evaluation of the imaginary part of a second order amplitude is traced back to an integration of the product of two born amplitudes over the relative angles. With this method the imaginary part of the helicity amplitudes for several subprocesses is calculated. The polarization in quark subprocesses with massive quarks is small. So we conclude that non-perturbative aspects are essential. As a model for non-perturbative effects we incorporate diquarks. They are considered as quasi-elementary constituents, beside quarks, within bayrons, which also take an active part in reactions in an medium range of momentum transfer. Spin 1-Diquarks constitute spin-flips on the born level. In order to investigate the polarization effects from quark and diquark subprocesses they were compared in different exclusive reactions within the framework of the spectator model. (orig./HSI) [de
Restoring unitarity in the Banados-Teitelboim-Zanelli black hole
International Nuclear Information System (INIS)
Solodukhin, Sergey N.
2005-01-01
Whether or not a system is unitary can be seen from the way it, if perturbed, relaxes back to equilibrium. The relaxation of a semiclassical black hole can be described in terms of a correlation function which exponentially decays with time. In the momentum space it is represented by an infinite set of complex poles to be identified with the quasinormal modes. This behavior is in sharp contrast to the relaxation in unitary theory in finite volume: the correlation function of the perturbation in this case is a quasiperiodic function of time and, in general, is expected to show the Poincare recurrences. In this paper I demonstrate how restore unitarity in the Banados-Teitelboim-Zanelli (BTZ) black hole, the simplest example of an eternal black hole in finite volume. I start with reviewing the relaxation in the semiclassical BTZ black hole and how this relaxation is mirrored in the boundary conformal field theory as suggested by the anti-de Sitter/conformal field theory correspondence. I analyze the sum over SL(2,Z) images of the BTZ space-time and suggest that it does not produce a quasiperiodic relaxation, as one might have hoped, but results in a correlation function which decays by power law. I develop an earlier suggestion and consider a nonsemiclassical deformation of the BTZ space-time that has the structure of a wormhole connecting two asymptotic regions semiclassically separated by a horizon. The small deformation parameter λ is supposed to have a nonperturbative origin to capture the finite N behavior of the boundary theory. The discrete spectrum of perturbation in the modified space-time is computed and is shown to determine the expected unitary behavior: the corresponding time evolution is quasiperiodic with a hierarchy of large time scales ln1/λ and 1/λ interpreted, respectively, as the Heisenberg and Poincare time scales in the system
A unitarized meson model including color Coulomb interaction
International Nuclear Information System (INIS)
Metzger, Kees.
1990-01-01
Ch. 1 gives a general introduction into the problem field of the thesis. It discusses in how far the internal structure of mesons is understood theoretically and which models exist. It discusses from a phenomenological point of view the problem of confinement indicates how quark models of mesons may provide insight in this phenomenon. In ch. 2 the formal theory of scattering in a system with confinement is given. It is shown how a coupled channel (CC) description and the work of other authors fit into this general framework. Explicit examples and arguments are given to support the CC treatment of such a system. In ch. 3 the full coupled-channel model as is employed in this thesis is presented. On the basis of arguments from the former chapters and the observed regularities in the experimental data, the choices underlying the model are supported. In this model confinement is described with a mass-dependent harmonic-oscillator potential and the presence of open (meson-meson) channels plays an essential role. In ch. 4 the unitarized model is applied to light scalar meson resonances. In this regime the contribution of the open channels is considerable. It is demonstrated that the model parameters as used for the description of the pseudo-scalar and vector mesons, unchanged can be used for the description of these mesons. Ch. 5 treats the color-Coulomb interaction. There the effect of the Coulomb interaction is studied in simple models without decay. The results of incorporating the color-Coulomb interaction into the full CC model are given in ch.6. Ch. 7 discusses the results of the previous chapters and the present status of the model. (author). 182 refs.; 16 figs.; 33 tabs
Non-Unitarity, sterile neutrinos, and Non-Standard neutrino Interactions
Blennow, Mattias; Fernandez-Martinez, Enrique; Hernandez-Garcia, Josu; Lopez-Pavon, Jacobo
2017-04-27
The simplest Standard Model extension to explain neutrino masses involves the addition of right-handed neutrinos. At some level, this extension will impact neutrino oscillation searches. In this work we explore the differences and similarities between the case in which these neutrinos are kinematically accessible (sterile neutrinos) or not (mixing matrix non-unitarity). We clarify apparent inconsistencies in the present literature when using different parametrizations to describe these effects and recast both limits in the popular neutrino non-standard interaction (NSI) formal- ism. We find that, in the limit in which sterile oscillations are averaged out at the near detector, their effects at the far detector coincide with non-unitarity at leading order, even in presence of a matter potential. We also summarize the present bounds existing in both limits and compare them with the expected sensitivities of near-future facilities taking the DUNE proposal as a bench- mark. We conclude that non-unitarity effects ...
The unitarity defect of the S-matrix and statistical multistep direct nuclear processes
International Nuclear Information System (INIS)
Hussein, M.S.
1986-09-01
A relation is derived which connects the unitarity defect function S + S-1 with the imaginary part of the absorptive potential responsible for the nuclear scattering. The concept of angle-dependent reaction cross-section is introduced for the purpose. A similar relation is also obtained for the equivalent quantity S + -S -1 . Several applications to nucler scattering are made, and possible relevance of this unitarity defect relation to statistical coupled channels theories of preequilibrium reactions is pointed out and discussed. (Author) [pt
Unitarity Bounds and RG Flows in Time Dependent Quantum Field Theory
Energy Technology Data Exchange (ETDEWEB)
Dong, Xi; Horn, Bart; Silverstein, Eva; Torroba, Gonzalo; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC
2012-04-05
We generalize unitarity bounds on operator dimensions in conformal field theory to field theories with spacetime dependent couplings. Below the energy scale of spacetime variation of the couplings, their evolution can strongly affect the physics, effectively shifting the infrared operator scaling and unitarity bounds determined from correlation functions in the theory. We analyze this explicitly for large-N double-trace flows, and connect these to UV complete field theories. One motivating class of examples comes from our previous work on FRW holography, where this effect explains the range of flavors allowed in the dual, time dependent, field theory.
International Nuclear Information System (INIS)
Iagolnitzer, D.
1983-11-01
Recent axiomatic results on the (non holonomic) analytic structure of the multiparticle S matrix and Green functions are reviewed and related general conjectures are described: (i) formal expansions of Green functions in terms of (holonomic) Feynman-type integrals in which each vertex represents an irreducible kernel, and (ii) ''graph by graph unitarity'' and other discontinuity formulae of the latter. These conjectures are closely linked with unitarity or asymptotic completeness equations, which they yield in a formal sense. In constructive field theory, a direct proof of the first conjecture (together with an independent proof of the second) would thus imply, as a first step, asymptotic completeness in that sense
Combined constraints on holographic bosonic technicolor
International Nuclear Information System (INIS)
Carone, Christopher D.; Primulando, Reinard
2010-01-01
We consider a model of strong electroweak symmetry breaking in which the expectation value of an additional, possibly composite, scalar field is responsible for the generation of fermion masses. The dynamics of the strongly coupled sector is defined and studied via its holographic dual, and does not correspond to a simple, scaled-up version of QCD. We consider the bounds from perturbative unitarity, the S parameter, and the mass of the Higgs-like scalar. We show that the combination of these constraints leaves a relatively limited region of parameter space viable, and suggests the qualitative features of the model that might be probed at the LHC.
On the unitarity of string propagation on SU(1,1)
International Nuclear Information System (INIS)
Mohammedi, N.
1989-12-01
We discuss the consistency (unitarity) of string propagation on the non-compact group SU(1,1) x G c and find the restrictions on the level of the Kac-Moody algebra for this propagation to be unitary. We also suggest some modifications to the Virasoro generators and obtain a manifestly unitary string theory. (author). 10 refs
Local distortion techniques and unitarity of the S-matrix for the 2-body problem
International Nuclear Information System (INIS)
Babbitt, D.; Balslev, E.
1976-01-01
The two-body S-matrix for an interaction with exponential decay at infinity is defined in a time-independent way and its unitarity is proved directly by local distortion techniques. Complete sets of incoming and outgoing states or delicate resolvent estimates are not needed for the proof
Non-unitarity of the leptonic mixing matrix in the TeV-scale type-I seesaw model
International Nuclear Information System (INIS)
Ohlsson, Tommy; Popa, Christoph; Zhang, He
2010-01-01
The non-unitarity effects in leptonic flavor mixing are regarded as one of the generic features of the type-I seesaw model. Therefore, we explore these effects in the TeV-scale type-I seesaw model, and show that there exist non-trivial correlations among the non-unitarity parameters, stemming from the typical flavor structure of the low-scale seesaw model. In general, it follows from analytical discussions and numerical results that all the six non-unitarity parameters are related to three model parameters, while the widely studied parameters η eτ and η μτ cannot be phenomenologically significant simultaneously.
DEFF Research Database (Denmark)
Mödersheim, Sebastian Alexander; Basin, David; Viganò, Luca
2010-01-01
We introduce constraint differentiation, a powerful technique for reducing search when model-checking security protocols using constraint-based methods. Constraint differentiation works by eliminating certain kinds of redundancies that arise in the search space when using constraints to represent...... results show that constraint differentiation substantially reduces search and considerably improves the performance of OFMC, enabling its application to a wider class of problems....
International Nuclear Information System (INIS)
Maggiore, M.; Shifman, M.
1993-01-01
We critically discuss recent works in which the premature unitarization mechanism is studied with the inclusion of non-nearest-neighbor interactions or beyond leading order in the energy. We also point out that the nonperturbative valley method gives inconsistent results when applied to fermion-number-violating amplitudes, and we argue that, independently of the mechanism of premature unitarization, the nonperturbative amplitudes which violate the fermion number are always exponentially suppressed
Coupling WW, ZZ unitarized amplitudes to γγ in the TeV region
Energy Technology Data Exchange (ETDEWEB)
Delgado, Rafael L.; Dobado, Antonio; Llanes-Estrada, Felipe J. [Universidad Complutense de Madrid, Departamento de Fisica Teorica I, Madrid (Spain)
2017-04-15
We define and calculate helicity partial-wave amplitudes for processes linking the Electroweak Symmetry Breaking Sector (EWSBS) to γγ, employing (to NLO) the Higgs-EFT (HEFT) extension of the Standard Model and the Equivalence Theorem, while neglecting all particle masses. The resulting amplitudes can be useful in the energy regime (500 GeV - 3 TeV). We also deal with their unitarization so that resonances of the EWSBS can simultaneously be described in the γγ initial or final states. Our resulting amplitudes satisfy unitarity, perturbatively in α, but for all s values. In this way we improve on the HEFT that fails as interactions become stronger with growing s and we provide a natural framework for the decay of dynamically generated resonances into WW, ZZ and γγ pairs. (orig.)
Multi-instantons at high energies: Premature unitarization and supercritical behavior
International Nuclear Information System (INIS)
Maggiore, M.; Shifman, M.
1992-01-01
We investigate the role of multi-instantons at high energies in weakly coupled theories. We perform an explicit computation of their effect and we find that they become as important as the one-instanton contribution at energies where the latter is still exponentially small (''premature unitarization''). The computation relies on various simplifying assumptions, and we discuss them. We argue, however, that premature unitarization is a phenomenon of a very general nature, which should survive our simplifying assumptions. If this is the case, there exists a critical energy where a change of regime is forced, and the dilute-instanton-gas approximation totally collapses. Possible scenarios in the critical and supercritical domain are discussed at the qualitative level
International Nuclear Information System (INIS)
Gajnutdinov, R.Kh.
1983-01-01
Possibility is studied to build the nonrelativistic scattering theory on the base of the general physical principles: causality, superposition, and unitarity, making no use of the Schroedinger formalism. The suggested approach is shown to be more general than the nonrelativistic scattering theory based on the Schroedinger equation. The approach is applied to build a model ofthe scattering theory for a system which consists of heavy nonrelativistic particles and a light relativistic particle
Unitarity cuts and Reduction to master integrals in d dimensions for one-loop amplitudes
Anastasiou, C; Feng, B; Kunszt, Z; Mastrolia, Pierpaolo; Anastasiou, Charalampos; Britto, Ruth; Feng, Bo; Kunszt, Zoltan; Mastrolia, Pierpaolo
2007-01-01
We present an alternative reduction to master integrals for one-loop amplitudes using a unitarity cut method in arbitrary dimensions. We carry out the reduction in two steps. The first step is a pure four-dimensional cut-integration of tree amplitudes with a mass parameter, and the second step is applying dimensional shift identities to master integrals. This reduction is performed at the integrand level, so that coefficients can be read out algebraically.
Unitarity limits on the mass and radius of dark matter particles
Griest, Kim; Kamionkowski, Marc
1989-01-01
Using partial wave unitarity and the observed density of the Universe, it is show that a stable elementary particle which was once in thermal equilibrium cannot have a mass greater than 340 TeV. An extended object which was once in thermal equilibrium cannot have a radius less than 7.5 x 10(exp -7) fm. A lower limit to the relic abundance of such particles is also found.
t-Channel unitarity construction of small-x kernels
International Nuclear Information System (INIS)
Coriano, C.; White, A.R.
1995-01-01
In the leading-log approximation, the small-x behavior of parton distributions in QCD is derived from the BFKL evolution equation. The authors describe the ion as a reggeon Bethe-Salpeter equation and discuss the use of reggeon diagrams to obtain 2-2 and 2-4 reggeon interactions at O(g 4 ). They then outline the dispersion theory basis of multiparticle j-plane analysis and describe how a gauge theory can be studied by combining Ward identity constraints with the group structure of reggeon interactions. Gluon reggeization, the O(g 2 ) BFKL kernel and O(g 4 ) corrections to it, are derived within this formalism. They give an explicit expression for the O(g 4 ) forward ''parton'' kernel in terms of logarithms and evaluate the eigenvalues. A separately infra-red finite component with a holomorphically factorizable spectrum is shown to be present and conjectured to be a new leading-order partial-wave amplitude. A comparison is made with Kirschner's discussion of O(g 4 ) contributions from the multi-Regge effective action
Nonviolent unitarization: basic postulates to soft quantum structure of black holes
Giddings, Steven B.
2017-12-01
A first-principles approach to the unitarity problem for black holes is systematically explored, based on the postulates of 1) quantum mechanics 2) the ability to approximately locally divide quantum gravitational systems into subsystems 3) correspondence with quantum field theory predictions for appropriate observers and (optionally) 4) universality of new gravitational effects. Unitarity requires interactions between the internal state of a black hole and its surroundings that have not been identified in the field theory description; correspondence with field theory indicates that these are soft. A conjectured information-theoretic result for information transfer between subsystems, partly motivated by a perturbative argument, then constrains the minimum coupling size of these interactions of the quantum atmosphere of a black hole. While large couplings are potentially astronomically observable, given this conjecture one finds that the new couplings can be exponentially small in the black hole entropy, yet achieve the information transfer rate needed for unitarization, due to the large number of black hole internal states. This provides a new possible alternative to arguments for large effects near the horizon. If universality is assumed, these couplings can be described as small, soft, state-dependent fluctuations of the metric near the black hole. Open questions include that of the more fundamental basis for such an effective picture.
Non-unitarity, sterile neutrinos, and non-standard neutrino interactions
Energy Technology Data Exchange (ETDEWEB)
Blennow, Mattias [Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Albanova University Center, 106 91 Stockholm (Sweden); Coloma, Pilar [Theoretical Physics Department, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Fernandez-Martinez, Enrique; Hernandez-Garcia, Josu [Departamento de Física Teórica, Universidad Autónoma de Madrid, Cantoblanco E-28049 Madrid (Spain); Instituto de Física Teórica UAM/CSIC, Calle Nicolás Cabrera 13-15, Cantoblanco E-28049 Madrid (Spain); Lopez-Pavon, Jacobo [INFN, Sezione di Genova, via Dodecaneso 33, 16146 Genova (Italy); CERN, Theoretical Physics Department, Geneva (Switzerland)
2017-04-27
The simplest Standard Model extension to explain neutrino masses involves the addition of right-handed neutrinos. At some level, this extension will impact neutrino oscillation searches. In this work we explore the differences and similarities between the case in which these neutrinos are kinematically accessible (sterile neutrinos) or not (mixing matrix non-unitarity). We clarify apparent inconsistencies in the present literature when using different parametrizations to describe these effects and recast both limits in the popular neutrino non-standard interaction (NSI) formalism. We find that, in the limit in which sterile oscillations are averaged out at the near detector, their effects at the far detector coincide with non-unitarity at leading order, even in presence of a matter potential. We also summarize the present bounds existing in both limits and compare them with the expected sensitivities of near-future facilities taking the DUNE proposal as a benchmark. We conclude that non-unitarity effects are too constrained to impact present or near future neutrino oscillation facilities but that sterile neutrinos can play an important role at long baseline experiments. The role of the near detector is also discussed in detail.
Global structure of curves from generalized unitarity cut of three-loop diagrams
International Nuclear Information System (INIS)
Hauenstein, Jonathan D.; Huang, Rijun; Mehta, Dhagash; Zhang, Yang
2015-01-01
This paper studies the global structure of algebraic curves defined by generalized unitarity cut of four-dimensional three-loop diagrams with eleven propagators. The global structure is a topological invariant that is characterized by the geometric genus of the algebraic curve. We use the Riemann-Hurwitz formula to compute the geometric genus of algebraic curves with the help of techniques involving convex hull polytopes and numerical algebraic geometry. Some interesting properties of genus for arbitrary loop orders are also explored where computing the genus serves as an initial step for integral or integrand reduction of three-loop amplitudes via an algebraic geometric approach.
Electron-positron annihilation: unitarity, scaling and electrodynamics at high energies
Energy Technology Data Exchange (ETDEWEB)
Karl, G [Guelph Univ., Ontario (Canada); European Organization for Nuclear Research, Geneva (Switzerland))
1974-01-01
The work on e/sup +/e/sup -/ annihilation by Cabibbo, Wolfenstein and the author is reviewed. The restrictions of unitarity are analyzed and the connection between the cross sections sigmasub(h) (into hadrons) and sigmasub(..mu..) (into muons) is derived. The possibility of non-scaling in e/sup +/e/sup -/ annihilation is studied and it is pointed out that it leads to no contradiction with presently available information. It is further pointed out that non-scaling could provide a cut-off mechanism for quantum electrodynamics.
Unitarization of Koerner-Kuroda model of electromagnetic structure of octet 1/2+ baryons
International Nuclear Information System (INIS)
Dubnicka, S.; Dubnickova, A.Z.
1994-10-01
The Koerner-Kuroda model of the electromagnetic structure of octet 1/2 + baryons is restored on a more topical physical basis. Electromagnetic radii of baryons under consideration are calculated and compared with other model predictions. By an incorporation of a two-cut approximation of correct form factor analytic properties and nonzero vector-meson widths, the Koerner-Kuroda model is unitarized, providing in this manner imaginary parts of the octet 1/2 + baryon form factors to be nonzero just starting from a branch point corresponding to the lowest threshold. (author). 32 refs, 16 figs, 2 tabs
Aaij, R.; Beteta, C. Abellan; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Cartelle, P. Alvarez; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Andreassi, G.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; d'Argent, P.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Bel, L. J.; Onderwater, C. J. G.; Pellegrino, A.; Tolk, S.
2016-01-01
The first study is presented of CP violation with an amplitude analysis of the Dalitz plot of B-0 -> DK+pi(-) decays, with D -> K+pi(-), K+K-, and pi(+)pi(-). The analysis is based on a data sample corresponding to 3.0 fb(-1) of pp collisions collected with the LHCb detector. No significant CP
International Nuclear Information System (INIS)
Huber, H.; Lun, D.R.; Allen, L.J.; Amos, K.
1997-01-01
The requirements that the scattering functions for quantal scattering at energies below the first inelastic threshold be unitary and analytic have been used to establish a process that gives the complex scattering amplitudes from differential cross sections. From those amplitudes scattering phase shifts have been deduced by Legendre integration. The effects of the natural ambiguity of the phase of the scattering phase shifts have been deduced by Legendre integration. The effects of the natural ambiguity of the phase of the scattering amplitude, under conditions for which uniqueness and (numerical) stability of solutions are not assured, also have been developed to specify the scattering phase shifts can give stable nonspurious results. The scattering of electrons from He atoms for incident energies ranging from 1.5 to 19 eV are considered as an example of the procedure. Phase shift analyses of that data have been made with a variety of other techniques to allow a comparative study of these results and of sets with which are associated fits to cross sections that are statistically significant. 18 refs., 2 tabs., 8 figs
αs and |Vcs| determination, and CKM unitarity test, from W decays at NNLO
Directory of Open Access Journals (Sweden)
David d'Enterria
2016-12-01
Full Text Available The hadronic (ΓhadW and total (ΓtotW widths of the W boson, computed at least at next-to-next-to-leading-order (NNLO accuracy, are combined to derive a new precise prediction for the hadronic W branching ratio BhadW ≡ ΓhadW/ΓtotW=0.682±0.011par, using the experimental Cabibbo–Kobayashi–Maskawa (CKM matrix elements, with uncertainties dominated by the input parameters of the calculations, or BhadW=0.6742±0.0002th±0.0001par assuming CKM unitarity. Comparing the theoretical predictions and experimental measurements for various W decay observables, the NNLO strong coupling constant at the Z pole, αs(mZ2=0.117±0.042exp±0.004th±0.001par, as well as the charm-strange CKM element, |Vcs|=0.973±0.004exp±0.002par, can be extracted under different assumptions. We also show that W decays provide today the most precise test of CKM unitarity for the 5 quarks lighter than mW, ∑u,c,d,s,b|Vij|2=1.999±0.008exp±0.001th. Perspectives for αs and |Vcs| extractions from W decays measurements at the LHC and future e+e− colliders are presented.
International Nuclear Information System (INIS)
Wittman, R.
1986-07-01
An impulse amplitude for pion photoproduction, suitable for the nuclear problem, is constructed with improved background dynamics and unitarity. The superior features of the amplitude are demonstrated at energies between threshold (E/sub γ/ = 150 MeV) and the Δ(1232) resonance energy (E/sub γ/ = 320 MeV) by discussing their effects on partial cross sections relevant to exclusive transitions in the 1p-shell. The specific reactions of 13 C(γ,π - ) 13 N/sub g.s./ and 14 N(γ,π + ) 14 C/sub g.s./ are discussed in light of these more general partial cross sections. The nuclear structure of the A = 14 system helps to enhance the effects considered. At or near resonance, very sizable (20 to 30%) effects arise both from the unitarity and from the refined treatment of the pionic final state interaction generated in the Δ-hole approach. Other examples of charged pion photoproduction reactions for 1p-shell nuclei are discussed briefly. Future theoretical improvements and experimental possibilities are suggested. 61 refs., 58 figs
Unitarity bounds for gauged axionic interactions and the Green-Schwarz mechanism
Energy Technology Data Exchange (ETDEWEB)
Coriano, C. [Universita del Salento and INFN Sezione di Lecce, Dipartimento di Fisica, Lecce (Italy); University of Crete, Department of Physics and Institute of Plasma Physics, Heraklion (Greece); Guzzi, M.; Morelli, S. [Universita del Salento and INFN Sezione di Lecce, Dipartimento di Fisica, Lecce (Italy)
2008-06-15
We analyze the effective actions of anomalous models in which a four-dimensional version of the Green-Schwarz mechanism is invoked for the cancellation of the anomalies, and we compare it with those models in which gauge invariance is restored by the presence of a Wess-Zumino term. Some issues concerning an apparent violation of unitarity of the mechanism, which requires Dolgov-Zakharov poles, are carefully examined, using a class of amplitudes studied in the past by Bouchiat-Iliopoulos-Meyer (BIM), and elaborating on previous studies. In the Wess-Zumino case we determine explicitly the unitarity bound using a realistic model of intersecting branes (the Madrid model) by studying the corresponding BIM amplitudes. This is shown to depend significantly on the Stueckelberg mass and on the coupling of the extra anomalous gauge bosons and allows one to identify standard-model-like regions (which are anomaly-free) from regions where the growth of certain amplitudes is dominated by the anomaly, separated by an inflection point, which could be studied at the LHC. The bound can even be around 5-10 TeV for a Z' mass around 1 TeV and varies sensitively with the anomalous coupling. The results for the WZ case are quite general and apply to all the models in which an axion-like interaction is introduced as a generalization of the Peccei-Quinn mechanism, with a gauged axion. (orig.)
Right unitarity triangles and tri-bimaximal mixing from discrete symmetries and unification
International Nuclear Information System (INIS)
Antusch, S.; King, Stephen F.; Luhn, Christoph; Spinrath, M.
2011-01-01
We propose new classes of models which predict both tri-bimaximal lepton mixing and a right-angled Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle, α∼90 o . The ingredients of the models include a supersymmetric (SUSY) unified gauge group such as SU(5), a discrete family symmetry such as A 4 or S 4 , a shaping symmetry including products of Z 2 and Z 4 groups as well as spontaneous CP violation. We show how the vacuum alignment in such models allows a simple explanation of α∼90 o by a combination of purely real or purely imaginary vacuum expectation values (vevs) of the flavons responsible for family symmetry breaking. This leads to quark mass matrices with 1-3 texture zeros that satisfy the 'phase sum rule' and lepton mass matrices that satisfy the 'lepton mixing sum rule' together with a new prediction that the leptonic CP violating oscillation phase is close to either 0 o , 90 o , 180 o , or 270 o depending on the model, with neutrino masses being purely real (no complex Majorana phases). This leads to the possibility of having right-angled unitarity triangles in both the quark and lepton sectors.
Combining experimental and cosmological constraints on heavy neutrinos
Directory of Open Access Journals (Sweden)
Marco Drewes
2017-08-01
Full Text Available We study experimental and cosmological constraints on the extension of the Standard Model by three right handed neutrinos with masses between those of the pion and W boson. We combine for the first time direct, indirect and cosmological constraints in this mass range. This includes experimental constraints from neutrino oscillation data, neutrinoless double β decay, electroweak precision data, lepton universality, searches for rare lepton decays, tests of CKM unitarity and past direct searches at colliders or fixed target experiments. On the cosmological side, big bang nucleosynthesis has the most pronounced impact. Our results can be used to evaluate the discovery potential of searches for heavy neutrinos at LHCb, BELLE II, SHiP, ATLAS, CMS or a future lepton collider.
Energy Technology Data Exchange (ETDEWEB)
M. Battaglia et al.
2004-04-02
This report contains the results of the Workshop on the CKM Unitarity Triangle that was held at CERN on 13-16 February 2002. There had been several Workshops on B physics that concentrated on studies at e{sup +}e{sup -} machines, at the Tevatron, or at LHC separately. Here we brought together experts of different fields, both theorists and experimentalists, to study the determination of the CKM matrix from all the available data of K, D, and B physics. The analysis of LEP data for B physics is reaching its end, and one of the goals of the Workshop was to underline the results that have been achieved at LEP, SLC, and CESR. Another goal was to prepare for the transfer of responsibility for averaging B physics properties, that has developed within the LEP community, to the present main actors of these studies, from the B factory and the Tevatron experiments. The optimal way to combine the various experimental and theoretical inputs and to fit for the apex of the Unitarity Triangle has been a contentious issue. A further goal of the Workshop was to bring together the proponents of different fitting strategies, and to compare their approaches when applied to the same inputs. Since lattice QCD plays a very important role in the determination of the non-perturbative parameters needed to constrain the CKM unitarity triangle, the first Workshop was seen as an excellent opportunity to bring together lattice theorists with the aim of establishing a working group to compile averages for phenomenologically relevant quantities. Representatives from lattice collaborations around the world were invited to attend a meeting during the Workshop. A consensus was reached to set up three test working groups, collectively known as the ''CKM Lattice Working Group'', to review a number of well-studied quantities: quark masses, the kaon B-parameter, and the matrix elements relevant for neutral B-meson mixing. This report is organized as a coherent document with chapters
International Nuclear Information System (INIS)
Batyunya, B.V.; Boguslavsky, I.V.; Gramenitsky, I.M.
1979-01-01
The difference between antiproton annihilation and pp interactions has been discussed. Charged particle multiplicity distributions in anti pp-interactions at 22.4 GeV/c were used to obtain antiproton annihilation characteristics. The comparison of the topological cross section of antipp interactions with those of non-diffractive pp interactions confirms the validity of dual unitarization
Energy Technology Data Exchange (ETDEWEB)
Nishijima, K; Sasaki, R [Tokyo Univ. (Japan). Dept. of Physics
1975-06-01
On the basis of the dispersion formulation of field theories the Schwinger term in spinor electrodynamics is shown to be a c-number. The essence of the proof consists in the dimensional argument and the characteristic features of the linear unitarity condition for a set of Green's functions involving the Schwinger term.
Energy Technology Data Exchange (ETDEWEB)
Ahn, C.
1989-08-01
We study two aspects of one loop structures in quantum field theories which describe two different areas of particle physics: the one loop unitarity behavior of the Standard Model of electroweak interactions and modular invariance of string model theory. Loop expansion has its importance in that it contains quantum fluctuations due to all physical states in the theory. Therefore, by studying the various models to one loop, we can understand how the contents of the theory can contribute to physically measurable quantities and how the consistency at quantum level restricts the physical states of the theory, as well. In the first half of the thesis, we study one loop corrections to the process {ital e}{sup +}{ital e}{sup {minus}} {yields} {ital W}{sup +}{ital W}{sup {minus}}. In this process, there is a delicate unitarity-saving cancellation between s-channel and t-channel tree level Feynman diagrams. If the one loop contribution due to heavy particles corrects the channels asymmetrically, the cancellation, hence unitarity, will be delayed up to the mass scale of these heavy particles. We refer to this phenomena as the unitarity delay effect. Due to this effect, cross section below these mass scales can have significant radiative corrections which may provide an appropriate window through which we can see the high energy structure of the Standard Model from relatively low energy experiments. In the second half, we will show how quantum consistency can restrict the physical states in string theory. 53 refs., 13 figs.
International Nuclear Information System (INIS)
Savard, G.; Buchinger, F.; Crawford, J.E.; Gulick, S.; Lee, J.K.P.; Clark, J.A.; Sharma, H.; Sharma, K.S.; Hardy, J.C.; Hecht, A.A.; Levand, A.F.; Scielzo, N.D.; Tanihata, I.; Villari, A.C.C.; Wang, Y.
2005-01-01
The masses of the radioactive nuclei 46 V and its decay daughter 46 Ti have been measured with the Canadian Penning Trap on-line Penning trap mass spectrometer to a precision of 1x10 -8 . A Q EC value of 7052.90(40) keV for the superallowed beta decay of 46 V is obtained from the difference of these two masses. With this precise Q value, the Ft value for this decay is determined with improved precision. An investigation of an earlier Q-value measurement for 46 V uncovers a set of 7 measurements that cannot be reconciled with modern data and affects previous evaluations of V ud from superallowed Fermi decays. A new evaluation, adding our new data and removing the discredited subset, yields new values for G V and V ud . When combined with recent results for V us , this yields modified constraints for the unitarity of the Cabibbo-Kobayashi-Maskawa matrix and other extensions of the standard model
One-loop calculations in quantum field theory: From Feynman diagrams to unitarity cuts
International Nuclear Information System (INIS)
Ellis, R. Keith; Kunszt, Zoltan; Melnikov, Kirill; Zanderighi, Giulia
2012-01-01
The success of the experimental program at the Tevatron re-inforced the idea that precision physics at hadron colliders is desirable and, indeed, possible. The Tevatron data strongly suggests that one-loop computations in QCD describe hard scattering well. Extrapolating this observation to the LHC, we conclude that knowledge of many short-distance processes at next-to-leading order may be required to describe the physics of hard scattering. While the field of one-loop computations is quite mature, parton multiplicities in hard LHC events are so high that traditional computational techniques become inefficient. Recently, new approaches based on unitarity have been developed for calculating one-loop scattering amplitudes in quantum field theory. These methods are especially suitable for the description of multi-particle processes in QCD and are amenable to numerical implementations. We present a systematic pedagogical description of both conceptual and technical aspects of the new methods.
QED on curved background and on manifolds with boundaries: Unitarity versus covariance
International Nuclear Information System (INIS)
Vassilevich, D.V.
1994-11-01
Some recent results show that the covariant path integral and the integral over physical degrees of freedom give contradicting results on curved background and on manifolds with boundaries. This looks like a conflict between unitarity and covariance. We argue that this effect is due to the use of non-covariant measure on the space of physical degrees of freedom. Starting with the reduced phase space path integral and using covariant measure throughout computations we recover standard path integral in the Lorentz gauge and the Moss and Poletti BRST-invariant boundary conditions. We also demonstrate by direct calculations that in the approach based on Gaussian path integral on the space of physical degrees of freedom some basic symmetries are broken. (author). 39 refs
One-loop calculations in quantum field theory: from Feynman diagrams to unitarity cuts
Energy Technology Data Exchange (ETDEWEB)
Ellis, R. Keith [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Kunszt, Zoltan [Institute for Theoretical Physics (Switzerland); Melnikov, Kirill [Johns Hopkins Univ., Baltimore, MD (United States); Zanderighi, Giulia [Rudolf Peierls Centre for Theoretical Physics (United Kingdom)
2012-09-01
The success of the experimental program at the Tevatron re-inforced the idea that precision physics at hadron colliders is desirable and, indeed, possible. The Tevatron data strongly suggests that one-loop computations in QCD describe hard scattering well. Extrapolating this observation to the LHC, we conclude that knowledge of many short-distance processes at next-to-leading order may be required to describe the physics of hard scattering. While the field of one-loop computations is quite mature, parton multiplicities in hard LHC events are so high that traditional computational techniques become inefficient. Recently new approaches based on unitarity have been developed for calculating one-loop scattering amplitudes in quantum field theory. These methods are especially suitable for the description of multi-particle processes in QCD and are amenable to numerical implementations. We present a systematic pedagogical description of both conceptual and technical aspects of the new methods.
A revised formula for 3-body recombination that cannot exceed the unitarity limit
International Nuclear Information System (INIS)
Greene, Chris H.; Esry, B.D.; Suno, H.
2004-01-01
We discuss the recent developments in theory and experiment that bear on our understanding of three-body recombination at ultracold temperatures. Some of these predictions include the fourth-power dependence of the three-body rate on the two-body scattering lenght a, the appearance of quantum mechanical shape resonance and Feshbach resonances, and the existence of destructive interference minima at large positive scattering lenghts. At very large scattering lenghts, however, the a 4 dependence of the recombination rate eventually will exceed the unitarity limit. We propose in this paper a simple way to correct this problem, permitting an approximate extension of previous predictions to slightly higher energies above the three-body fragmentation threshold. A preliminary comparison is carried out with a very recent experiment by Grimm and coworkers, showing reasonable agreement
Bound-state formation for thermal relic dark matter and unitarity
International Nuclear Information System (INIS)
Harling, Benedict von; Petraki, Kalliopi
2014-01-01
We show that the relic abundance of thermal dark matter annihilating via a long-range interaction, is significantly affected by the formation and decay of dark matter bound states in the early universe, if the dark matter mass is above a few TeV . We determine the coupling required to obtain the observed dark matter density, taking into account both the direct 2-to-2 annihilations and the formation of bound states, and provide an analytical fit. We argue that the unitarity limit on the inelastic cross-section is realized only if dark matter annihilates via a long-range interaction, and we determine the upper bound on the mass of thermal-relic dark matter to be about 197 (139) TeV for (non)-self-conjugate dark matter
Unitarized model of inclusive and diffractive DIS with Q2 evolution
International Nuclear Information System (INIS)
Armesto, Nestor; Salgado, Carlos A.; Tywoniuk, Konrad; Kaidalov, Alexei B.
2010-01-01
We discuss the interplay of low-x physics and QCD scaling violations by extending the unified approach describing inclusive structure functions and diffractive production in γ*p interactions proposed in previous papers to large values of Q 2 . We describe the procedure of extracting, from the nonperturbative model, initial conditions for the QCD evolution that respect unitarity. Assuming Regge factorization of the diffractive structure function, a similar procedure is proposed for the calculation of hard diffraction. The results are in good agreement with experimental data on the proton structure function F 2 and the most recent data on the reduced diffractive cross section, x P σ r D(3) . Predictions for both F 2 and F L are presented in a wide kinematical range and compared to calculations within high-energy QCD.
WIMP Dark Matter and Unitarity-Conserving Inflation via a Gauge Singlet Scalar
International Nuclear Information System (INIS)
Kahlhoefer, Felix; McDonald, John
2015-07-01
A gauge singlet scalar with non-minimal coupling to gravity can drive inflation and later freeze out to become cold dark matter. We explore this idea by revisiting inflation in the singlet direction (S-inflation) and Higgs Portal Dark Matter in light of the Higgs discovery, limits from LUX and observations by Planck. We show that large regions of parameter space remain viable, so that successful inflation is possible and the dark matter relic abundance can be reproduced. Moreover, the scalar singlet can stabilise the electroweak vacuum and at the same time overcome the problem of unitarity-violation during inflation encountered by Higgs Inflation, provided the singlet is a real scalar. The 2-σ Planck upper bound on n s imposes that the singlet mass is below 2 TeV, so that almost the entire allowed parameter range can be probed by XENON1T.
Constraints on Non-Standard Contributions to the Charged-Current Interactions
Hagiwara, K; Hagiwara, Kaoru; Matsumoto, Seiji
1998-01-01
The success of the quantum level predictions of the Standard Model on the $Z$ boson properties, on $\\mw$ and on $\\mt$, which makes use of the muon lifetime as an input, implies a stringent constraint on new physics contributions to the $V-A$ charged-current interactions among leptons. Observed unitarity of the CKM matrix elements then implies constraints on non-standard contributions to the lepton-quark charged-current interactions. By using the recent electroweak data as inputs, we find the 95% CL limits for the corresponding contact interactions: $\\Lambda_{CC,+}^{\\ell\\ell}>7.5$ TeV and the lepton-quark contact interactions.
International Nuclear Information System (INIS)
Provost, J.
1984-01-01
Accurate tests of the theory of stellar structure and evolution are available from the Sun's observations. The solar constraints are reviewed, with a special attention to the recent progress in observing global solar oscillations. Each constraint is sensitive to a given region of the Sun. The present solar models (standard, low Z, mixed) are discussed with respect to neutrino flux, low and high degree five-minute oscillations and low degree internal gravity modes. It appears that actually there do not exist solar models able to fully account for all the observed quantities. (Auth.)
Aspects of CP violation with the BABAR detector. Constraints on the CKM Matrix
International Nuclear Information System (INIS)
Roos, L.
2004-09-01
This document presents the work done within the BABAR Collaboration as well as a phenomenological study on the interpretation of the B measurements related to the Unitarity Triangle. The read-out electronics of the Cerenkov detector, the DIRC, and especially the Time-Digital-Converter designed at LPNHE are described. Two major results of the BABAR Collaboration are presented: the measurement of the sin(2β) parameter in the b → ccs modes, which has established the CP violation in the B sector in 2001 and the study of CP asymmetries in the B 0 → π + π - channel. The constraints on the Unitarity Triangle from the K 0 K 0 system, the B semi-leptonic decays, the B oscillation parameters are in excellent agreement with those from sin(2β) and α. (author)
International Nuclear Information System (INIS)
Jones, P.M.S.
1987-01-01
There are considerable incentives for the use of nuclear in preference to other sources for base load electricity generation in most of the developed world. These are economic, strategic, environmental and climatic. However, there are two potential constraints which could hinder the development of nuclear power to its full economic potential. These are public opinion and financial regulations which distort the nuclear economic advantage. The concerns of the anti-nuclear lobby are over safety, (especially following the Chernobyl accident), the management of radioactive waste, the potential effects of large scale exposure of the population to radiation and weapons proliferation. These are discussed. The financial constraint is over two factors, the availability of funds and the perception of cost, both of which are discussed. (U.K.)
Verma, Surender; Bhardwaj, Shankita
2018-05-01
We have investigated a possible connection between the Majorana phases and geometric parameters of Majorana unitarity triangle (MT) in two-texture zero neutrino mass matrix. Such analytical relations can, also, be obtained for other theoretical models viz. hybrid textures, neutrino mass matrix with vanishing minors and have profound implications for geometric description of C P violation. As an example, we have considered the two-texture zero neutrino mass model to obtain a relation between Majorana phases and MT parameters that may be probed in various lepton number violating processes. In particular, we find that Majorana phases depend on only one of the three interior angles of the MT in each class of two-texture zero neutrino mass matrix. We have also constructed the MT for class A , B , and C neutrino mass matrices. Nonvanishing areas and nontrivial orientations of these Majorana unitarity triangles indicate nonzero C P violation as a generic feature of this class of mass models.
International Nuclear Information System (INIS)
Davies, Scott
2011-01-01
We combine the six-dimensional helicity formalism of Cheung and O'Connell with D-dimensional generalized unitarity to obtain a new formalism for computing one-loop amplitudes in dimensionally regularized QCD. With this procedure, we simultaneously obtain the pieces that are constructible from four-dimensional unitarity cuts and the rational pieces that are missed by them, while retaining a helicity formalism. We illustrate the procedure using four- and five-point one-loop amplitudes in QCD, including examples with external fermions. We also demonstrate the technique's effectiveness in next-to-leading order QCD corrections to Higgs processes by computing the next-to-leading order correction to the Higgs plus three positive-helicity gluons amplitude in the large top-quark mass limit.
Directory of Open Access Journals (Sweden)
Peter Bußjäger
2010-04-01
Full Text Available The following article describes current challenges of Austrian federalism. On ground of the Federal Constitution from 1920 Austria is a federation with nine autonomous Länder. Federalism is one of the basic principles of the constitution. Nevertheless the Länder are faced with centralizing drive due to Europeanization and unitarism. On the other hand the Länder have a strong regional identity. The Länder are emotionally deeply rooted in theAustrian population. The Länder also participate well in the decision making process on European level.Nevertheless the division of competencies both in legislation and administration between Federation and Länder is complicated and needs to be modernised. In the past various reform projects on federal level had failed while various reforms in the Land constitutions have led to more innovation on Land level. Despite these facts paradigms of reform debates on Austria´s federal system have changed: Until the early nineties of 20th century constitutionalreforms aimed to strengthen the role of the Länder. Since Austria´saccession to the EU reform projects the efficiency of the federal structures of Austria are doubted. Economical and financial crisis probably will increase the pressure for structural reforms.
Higgs Spin Determination and Unitarity of Vector-boson Scattering at the LHC
Frank, Jessica
After the discovery of a new particle at the Large Hadron Collider (LHC), it is crucial to definitely verify or disprove whether this new 125 − 126 GeV resonance is the Higgs boson of the Standard Model (SM). Thus, its features, including its spin, have to be determined. In order to distinguish the two most likely spin hypotheses, spin-0 or spin-2, the phenomenology of light spin-2 resonances produced in different gluon-fusion and vectorboson-fusion processes at the LHC is studied. Starting from an effective model for the interaction of a spin-2 particle with SM gauge bosons, cross sections and differential distributions are calculated within the Monte Carlo program Vbfnlo. Whereas with specific model parameters, such a spin-2 resonance can mimic rates and transverse-momentum distributions of a SM Higgs boson in the main decay channels γγ, WW and ZZ, several distributions allow to separate spin-2 from spin-0, almost independently of model parameters. Since the SM Higgs boson ensures the unitarity of the S...
Right unitarity triangles, stable CP-violating phases and approximate quark-lepton complementarity
International Nuclear Information System (INIS)
Xing Zhizhong
2009-01-01
Current experimental data indicate that two unitarity triangles of the CKM quark mixing matrix V are almost the right triangles with α∼90 deg. We highlight a very suggestive parametrization of V and show that its CP-violating phase φ is nearly equal to α (i.e., φ-α∼1.1 deg.). Both φ and α are stable against the renormalizaton-group evolution from the electroweak scale M Z to a superhigh energy scale M X or vice versa, and thus it is impossible to obtain α=90 deg. at M Z from φ=90 deg. at M X . We conjecture that there might also exist a maximal CP-violating phase φ∼90 deg. in the MNS lepton mixing matrix U. The approximate quark-lepton complementarity relations, which hold in the standard parametrizations of V and U, can also hold in our particular parametrizations of V and U simply due to the smallness of |V ub | and |V e3 |.
Self-unitarization of New Higgs Inflation and compatibility with Planck and BICEP2 data
International Nuclear Information System (INIS)
Germani, Cristiano; Wintergerst, Nico; Watanabe, Yuki
2014-01-01
In this paper we show that the Germani-Kehagias model of Higgs inflation (or New Higgs Inflation), where the Higgs boson is kinetically non-minimally coupled to the Einstein tensor is in perfect compatibility with the latest Planck and BICEP2 data. Moreover, we show that the tension between the Planck and BICEP2 data can be relieved within the New Higgs inflation scenario by a negative running of the spectral index. Regarding the unitarity of the model, we argue that it is unitary throughout the evolution of the Universe. Weak couplings in the Higgs-Higgs and Higgs-graviton sectors are provided by a large background dependent cut-off scale during inflation. In the same regime, the W and Z gauge bosons acquire a very large mass, thus decouple. On the other hand, if they are also non-minimally coupled to the Higgs boson, their effective masses can be enormously reduced. In this case, the W and Z bosons are no longer decoupled. After inflation, the New Higgs model is well approximated by a quartic Galileon with a renormalizable potential. We argue that this can unitarily create the right conditions for inflation to eventually start
Self-unitarization of New Higgs Inflation and compatibility with Planck and BICEP2 data
Energy Technology Data Exchange (ETDEWEB)
Germani, Cristiano; Wintergerst, Nico [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, Theresienstr. 37, 80333 München (Germany); Watanabe, Yuki, E-mail: cristiano.germani@lmu.de, E-mail: watanabe@resceu.s.u-tokyo.ac.jp, E-mail: nico.wintergerst@physik.lmu.de [Research Center for the Early Universe, University of Tokyo, Tokyo 113-0033 (Japan)
2014-12-01
In this paper we show that the Germani-Kehagias model of Higgs inflation (or New Higgs Inflation), where the Higgs boson is kinetically non-minimally coupled to the Einstein tensor is in perfect compatibility with the latest Planck and BICEP2 data. Moreover, we show that the tension between the Planck and BICEP2 data can be relieved within the New Higgs inflation scenario by a negative running of the spectral index. Regarding the unitarity of the model, we argue that it is unitary throughout the evolution of the Universe. Weak couplings in the Higgs-Higgs and Higgs-graviton sectors are provided by a large background dependent cut-off scale during inflation. In the same regime, the W and Z gauge bosons acquire a very large mass, thus decouple. On the other hand, if they are also non-minimally coupled to the Higgs boson, their effective masses can be enormously reduced. In this case, the W and Z bosons are no longer decoupled. After inflation, the New Higgs model is well approximated by a quartic Galileon with a renormalizable potential. We argue that this can unitarily create the right conditions for inflation to eventually start.
The measurements of angle γ of the unitarity triangle with the BaBar detector
International Nuclear Information System (INIS)
Derkach, D.
2010-06-01
In this thesis, we present studies of the B mesons system performed using the full dataset collected by the BABAR experiment at the PEP-II collider at SLAC. The first analysis presented here is the search of the rare V ub mediated decays B + → D + K *0 . The experimental analysis is performed looking at several D + decay modes. No signals have been found and upper limits have been set to be: Br(B + → D + K 0 ) -6 at 90% prob.; Br(B + → D + K *0 ) -6 at 90% prob. In the second part we present the CP violation studies in the B-meson system, and in particular the measurements of the γ angle of the unitarity triangle. The γ angle is the relative weak phase between the V ub and V cb elements of the CKM matrix. We present and describe the analysis using the charged B meson decays: B + → D 0 K + . These decays are studied through the ADS method, where the neutral D mesons are reconstructed into Kππ 0 final states. Combining this analysis with a similar one that used Kπ as a D 0 final state, we have obtained the following values: ratio r(DK) 0.083+0.028-0.043; γ angle = (86+51-45) degrees. If the results of this thesis are used in the full system of the B → DK and B → DK * decay amplitudes, other interesting results can be obtained. The error on the ratio r(DK * ) for the charged B decays is improved by a factor 3 resulting in r(DK * ) = (0.08 ± 0.03). The ration between the V ub mediated annihilation (A) and the color suppressed (C) amplitudes is obtained to be A/C 0 ) for neutral B decays is found to be (0.27 ± 0.09)
Multi-Higgs doublet models: physical parametrization, sum rules and unitarity bounds
Bento, Miguel P.; Haber, Howard E.; Romão, J. C.; Silva, João P.
2017-11-01
If the scalar sector of the Standard Model is non-minimal, one might expect multiple generations of the hypercharge-1/2 scalar doublet analogous to the generational structure of the fermions. In this work, we examine the structure of a Higgs sector consisting of N Higgs doublets (where N ≥ 2). It is particularly convenient to work in the so-called charged Higgs basis, in which the neutral Higgs vacuum expectation value resides entirely in the first Higgs doublet, and the charged components of remaining N - 1 Higgs doublets are mass-eigenstate fields. We elucidate the interactions of the gauge bosons with the physical Higgs scalars and the Goldstone bosons and show that they are determined by an N × 2 N matrix. This matrix depends on ( N - 1)(2 N - 1) real parameters that are associated with the mixing of the neutral Higgs fields in the charged Higgs basis. Among these parameters, N - 1 are unphysical (and can be removed by rephasing the physical charged Higgs fields), and the remaining 2( N - 1)2 parameters are physical. We also demonstrate a particularly simple form for the cubic interaction and some of the quartic interactions of the Goldstone bosons with the physical Higgs scalars. These results are applied in the derivation of Higgs coupling sum rules and tree-level unitarity bounds that restrict the size of the quartic scalar couplings. In particular, new applications to three Higgs doublet models with an order-4 CP symmetry and with a Z_3 symmetry, respectively, are presented.
How to determine all the angles of the unitarity triangle from Bd0 → DKS and Bs0 → Dφ
International Nuclear Information System (INIS)
Gronau, M.; London, D.
1990-10-01
We consider within the standard model the time-dependent decay rates of the three processes B d 0 → D 0 Ks.anti D 0 Ks and D 1 0 Ks, where D 1 0 is a neutral D meson CP-eigenstate. We show that it is possible to derive from these processes, in which two weak amplitudes are involved, two of the three angles in the unitarity triangle of the Cabibbo-Kobayashi-Maskawa matrix. The third angle can be determined from B s 0 → DΦ. All three angles are obtained free of hadronic final-state uncertainties. (orig.)
(Beta)-decay experiments and the unitarity of the CKM matrix
International Nuclear Information System (INIS)
Garrett, P E
2005-01-01
The goal of this project was to perform very precise measurements of super-allowed Fermi β decay in order to investigate a possible non-unitarity in the CKM matrix of the Standard Model of particle physics. Current data from 9 precisely measured β decays indicated that the sum-of-squares of the first row of the CKM matrix differs from 1.0 at the 2.2σ (or 98% confidence) level. If true, it would be the first firm indication of physics beyond the Standard Model--the model that has been the backbone of the worldwide physics community for more than 30 years. The physics goal of the project was to test and constrain the calculated correction factors that must be applied to the experimental data by performing measurements at the TRIUMF radioactive ion beam facility ISAC. Accurate and precise (precision goal >99.9%) half lives and decay branching ratios were measured for nuclei where different sets of calculated corrections give divergent results thereby allowing us to determine which theory, if any, gives the correct result. The LLNL contribution was to design and build the data acquisition system that will enable the experiments, and to provide theoretical calculations necessary for the interpretation of the results. The first planned measurement was 34 Ar, to be followed by 62 Ga and 74 Rb. However, there were major problems in creating a suitable, intense beam of radioactive 34 Ar. The collaboration decided to proceed with measurements on 62 Ga and 18 Ne. These experiments were performed in a series of measurements in the summer and fall of 2004. The LLNL team also is leading the effort to perform measurements on 66 As and 70 Br that are expected during 2006-2008. While the definitive experiments to meet the goals of the LDRD were not conducted during the funding period, the involvement in the radioactive program at TRIUMF has lead to a number of new initiatives, and has attracted new staff to LLNL. This LDRD has laid the foundation for involvement in one of the
International Nuclear Information System (INIS)
Khorrami, M.
1995-01-01
A general formulation for discrete-time quantum mechanics, based on Feynman's method in ordinary quantum mechanics, is presented. It is shown that the ambiguities present in ordinary quantum mechanics (due to noncommutativity of the operators), are no longer present here. Then the criteria for the unitarity of the evolution operator are examined. It is shown that the unitarity of the evolution operator puts restrictions on the form of the action, and also implies the existence of a solution for the classical initial-value problem. 13 refs
Directory of Open Access Journals (Sweden)
Chengcheng Han
2016-09-01
Full Text Available Perturbative unitarity conditions have been playing an important role in estimating the energy scale of new physics, including the Higgs mass as the most important example. In this letter, we show that there is a possibility to see the hint of a new physics (top quark partner indirectly by observing an “apparent” unitarity violation in the distribution of invariant mass of b-jet and W-boson (Mbw well above the mass of a top quark in a process of a heavy resonance decaying into a pair of top quarks.
Prospects for the measurement of the unitarity triangle angle γ from B0→DK+π- decays
International Nuclear Information System (INIS)
Gershon, Tim; Williams, Mike
2009-01-01
The potential for a precise measurement of the unitarity triangle angle γ in future experiments from the decay B 0 →DK* 0 is well known. It has recently been suggested that the sensitivity can be significantly enhanced by analyzing the B 0 →DK + π - Dalitz plot to extract amplitudes relative to those of the flavor-specific decay B 0 →D 2 * - K + . An extension to this method which includes the case where the neutral D meson is reconstructed in suppressed final states is presented. The sensitivity to γ is estimated using this method and compared to that obtained using the B 0 →DK* 0 decay alone. Experimental effects, such as background contamination, are also considered. This approach appears to be a highly attractive addition to the family of methods that can be used to determine γ.
Study of open-charm 0{sup +} states in unitarized chiral effective theory with one-loop potentials
Energy Technology Data Exchange (ETDEWEB)
Du, Meng-Lin [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Guo, Feng-Kun [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China); University of Chinese Academy of Sciences, School of Physical Sciences, Beijing (China); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Forschungszentrum Juelich, Institute for Advanced Simulation, Institut fuer Kernphysik and Juelich Center for Hadron Physics (Germany); Yao, De-Liang [Forschungszentrum Juelich, Institute for Advanced Simulation, Institut fuer Kernphysik and Juelich Center for Hadron Physics (Germany); Instituto de Fisica Corpuscular (Centro mixto CSIC-UV), Institutos de Investigacion de Paterna, Valencia (Spain)
2017-11-15
Chiral potentials are derived for the interactions between Goldstone bosons and pseudo-scalar charmed mesons up to next-to-next-to-leading order in a covariant chiral effective field theory with explicit vector charmed-meson degrees of freedom. Using the extended-on-mass-shell scheme, we demonstrate that the ultraviolet divergences and the so-called power counting breaking terms can be properly absorbed by the low-energy constants of the chiral Lagrangians. We calculate the scattering lengths by unitarizing the one-loop potentials and fit them to the data extracted from lattice QCD. The obtained results are compared to the ones without an explicit contribution of vector charmed mesons given previously. It is found that the difference is negligible for S-wave scattering in the threshold region. This validates the use of D*-less one-loop potentials in the study of the pertinent scattering lengths. We search for dynamically generated open-charm states with J{sup P} = 0{sup +} as poles of the S-matrix on various Riemann sheets. The trajectories of those poles for varying pion masses are presented as well. (orig.)
International Nuclear Information System (INIS)
Chivukula, R. Sekhar; Christensen, Neil D.; Simmons, Elizabeth H.
2008-01-01
We discuss the properties of a model incorporating both a scalar electroweak Higgs doublet and an electroweak Higgs triplet. We construct the low-energy effective theory for the light Higgs doublet in the limit of small (but nonzero) deviations in the ρ parameter from one, a limit in which the triplet states become heavy. For Δρ>0, perturbative unitarity of WW scattering breaks down at a scale inversely proportional to the renormalized vacuum expectation value of the triplet field (or, equivalently, inversely proportional to the square root of Δρ). This result imposes an upper limit on the mass scale of the heavy triplet bosons in a perturbative theory; we show that this upper bound is consistent with dimensional analysis in the low-energy effective theory. Recent articles have shown that the triplet bosons do not decouple, in the sense that deviations in the ρ parameter from one do not necessarily vanish at one-loop in the limit of large triplet mass. We clarify that, despite the nondecoupling behavior of the Higgs triplet, this model does not violate the decoupling theorem since it incorporates a large dimensionful coupling. Nonetheless, we show that if the triplet-Higgs boson masses are of order the grand unified theory scale, perturbative consistency of the theory requires the (properly renormalized) Higgs-triplet vacuum expectation value to be so small as to be irrelevant for electroweak phenomenology
Financing Constraints and Entrepreneurship
William R. Kerr; Ramana Nanda
2009-01-01
Financing constraints are one of the biggest concerns impacting potential entrepreneurs around the world. Given the important role that entrepreneurship is believed to play in the process of economic growth, alleviating financing constraints for would-be entrepreneurs is also an important goal for policymakers worldwide. We review two major streams of research examining the relevance of financing constraints for entrepreneurship. We then introduce a framework that provides a unified perspecti...
Temporal Concurrent Constraint Programming
DEFF Research Database (Denmark)
Nielsen, Mogens; Valencia Posso, Frank Dan
2002-01-01
The ntcc calculus is a model of non-deterministic temporal concurrent constraint programming. In this paper we study behavioral notions for this calculus. In the underlying computational model, concurrent constraint processes are executed in discrete time intervals. The behavioral notions studied...... reflect the reactive interactions between concurrent constraint processes and their environment, as well as internal interactions between individual processes. Relationships between the suggested notions are studied, and they are all proved to be decidable for a substantial fragment of the calculus...
Temporal Concurrent Constraint Programming
DEFF Research Database (Denmark)
Nielsen, Mogens; Palamidessi, Catuscia; Valencia, Frank Dan
2002-01-01
The ntcc calculus is a model of non-deterministic temporal concurrent constraint programming. In this paper we study behavioral notions for this calculus. In the underlying computational model, concurrent constraint processes are executed in discrete time intervals. The behavioral notions studied...
Evaluating Distributed Timing Constraints
DEFF Research Database (Denmark)
Kristensen, C.H.; Drejer, N.
1994-01-01
In this paper we describe a solution to the problem of implementing time-optimal evaluation of timing constraints in distributed real-time systems.......In this paper we describe a solution to the problem of implementing time-optimal evaluation of timing constraints in distributed real-time systems....
DEFF Research Database (Denmark)
Michelsen, Aage U.
2004-01-01
Tankegangen bag Theory of Constraints samt planlægningsprincippet Drum-Buffer-Rope. Endvidere skitse af The Thinking Process.......Tankegangen bag Theory of Constraints samt planlægningsprincippet Drum-Buffer-Rope. Endvidere skitse af The Thinking Process....
Energy Technology Data Exchange (ETDEWEB)
Baldes, Iason [DESY, Notkestraße 85, Hamburg, D-22607 Germany (Germany); Petraki, Kalliopi, E-mail: iason.baldes@desy.de, E-mail: kpetraki@lpthe.jussieu.fr [Laboratoire de Physique Théorique et Hautes Energies (LPTHE), UMR 7589 CNRS and UPMC, 4 Place Jussieu, Paris, F-75252 France (France)
2017-09-01
Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s -wave and p -wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.
International Nuclear Information System (INIS)
Baldes, Iason; Petraki, Kalliopi
2017-03-01
Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s-wave and p-wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.
Energy Technology Data Exchange (ETDEWEB)
Baldes, Iason [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Petraki, Kalliopi [Nationaal Instuut voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands); UMR 7589 CNRS et UPMC, Paris (France). Laboratoire de Physique Theorique et Hautes Energies (LPTHE)
2017-03-15
Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s-wave and p-wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.
International Nuclear Information System (INIS)
Baldes, Iason; Petraki, Kalliopi
2017-01-01
Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s -wave and p -wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.
Directory of Open Access Journals (Sweden)
Arnaud Gotlieb
2013-02-01
Full Text Available Iterative imperative programs can be considered as infinite-state systems computing over possibly unbounded domains. Studying reachability in these systems is challenging as it requires to deal with an infinite number of states with standard backward or forward exploration strategies. An approach that we call Constraint-based reachability, is proposed to address reachability problems by exploring program states using a constraint model of the whole program. The keypoint of the approach is to interpret imperative constructions such as conditionals, loops, array and memory manipulations with the fundamental notion of constraint over a computational domain. By combining constraint filtering and abstraction techniques, Constraint-based reachability is able to solve reachability problems which are usually outside the scope of backward or forward exploration strategies. This paper proposes an interpretation of classical filtering consistencies used in Constraint Programming as abstract domain computations, and shows how this approach can be used to produce a constraint solver that efficiently generates solutions for reachability problems that are unsolvable by other approaches.
Resources, constraints and capabilities
Dhondt, S.; Oeij, P.R.A.; Schröder, A.
2018-01-01
Human and financial resources as well as organisational capabilities are needed to overcome the manifold constraints social innovators are facing. To unlock the potential of social innovation for the whole society new (social) innovation friendly environments and new governance structures
Design with Nonlinear Constraints
Tang, Chengcheng
2015-01-01
. The first application is the design of meshes under both geometric and static constraints, including self-supporting polyhedral meshes that are not height fields. Then, with a formulation bridging mesh based and spline based representations, the application
Dynamics and causality constraints
International Nuclear Information System (INIS)
Sousa, Manoelito M. de
2001-04-01
The physical meaning and the geometrical interpretation of causality implementation in classical field theories are discussed. Causality in field theory are kinematical constraints dynamically implemented via solutions of the field equation, but in a limit of zero-distance from the field sources part of these constraints carries a dynamical content that explains old problems of classical electrodynamics away with deep implications to the nature of physicals interactions. (author)
Momentum constraint relaxation
International Nuclear Information System (INIS)
Marronetti, Pedro
2006-01-01
Full relativistic simulations in three dimensions invariably develop runaway modes that grow exponentially and are accompanied by violations of the Hamiltonian and momentum constraints. Recently, we introduced a numerical method (Hamiltonian relaxation) that greatly reduces the Hamiltonian constraint violation and helps improve the quality of the numerical model. We present here a method that controls the violation of the momentum constraint. The method is based on the addition of a longitudinal component to the traceless extrinsic curvature A ij -tilde, generated by a vector potential w i , as outlined by York. The components of w i are relaxed to solve approximately the momentum constraint equations, slowly pushing the evolution towards the space of solutions of the constraint equations. We test this method with simulations of binary neutron stars in circular orbits and show that it effectively controls the growth of the aforementioned violations. We also show that a full numerical enforcement of the constraints, as opposed to the gentle correction of the momentum relaxation scheme, results in the development of instabilities that stop the runs shortly
International Nuclear Information System (INIS)
Sugier, A.
2003-01-01
The selected new constraints should be consistent with the scale of concern i.e. be expressed roughly as fractions or multiples of the average annual background. They should take into account risk considerations and include the values of the currents limits, constraints and other action levels. The recommendation is to select four leading values for the new constraints: 500 mSv ( single event or in a decade) as a maximum value, 0.01 mSv/year as a minimum value; and two intermediate values: 20 mSv/year and 0.3 mSv/year. This new set of dose constraints, representing basic minimum standards of protection for the individuals taking into account the specificity of the exposure situations are thus coherent with the current values which can be found in ICRP Publications. A few warning need however to be noticed: There is no more multi sources limit set by ICRP. The coherence between the proposed value of dose constraint (20 mSv/year) and the current occupational dose limit of 20 mSv/year is valid only if the workers are exposed to one single source. When there is more than one source, it will be necessary to apportion. The value of 1000 mSv lifetimes used for relocation can be expressed into annual dose, which gives approximately 10 mSv/year and is coherent with the proposed dose constraint. (N.C.)
Swain, J D
1999-01-01
We present a new method for the determination of the Cabibbo- Kobayashi-Maskawa quark mixing matrix element V/sub tb/ from electroweak loop corrections, in particular those affecting the process Z to bb. From a combined analysis of results from the LEP, SLC, Tevatron, and neutrino scattering experiments we determine V /sub tb/=0.77/sub -0.24//sup +18/. We comment briefly on the implications of this measurement for the mass of the top quark and Higgs boson, alpha /sub s/, and CKM unitarity. (19 refs).
Misconceptions and constraints
International Nuclear Information System (INIS)
Whitten, M.; Mahon, R.
2005-01-01
In theory, the sterile insect technique (SIT) is applicable to a wide variety of invertebrate pests. However, in practice, the approach has been successfully applied to only a few major pests. Chapters in this volume address possible reasons for this discrepancy, e.g. Klassen, Lance and McInnis, and Robinson and Hendrichs. The shortfall between theory and practice is partly due to the persistence of some common misconceptions, but it is mainly due to one constraint, or a combination of constraints, that are biological, financial, social or political in nature. This chapter's goal is to dispel some major misconceptions, and view the constraints as challenges to overcome, seeing them as opportunities to exploit. Some of the common misconceptions include: (1) released insects retain residual radiation, (2) females must be monogamous, (3) released males must be fully sterile, (4) eradication is the only goal, (5) the SIT is too sophisticated for developing countries, and (6) the SIT is not a component of an area-wide integrated pest management (AW-IPM) strategy. The more obvious constraints are the perceived high costs of the SIT, and the low competitiveness of released sterile males. The perceived high up-front costs of the SIT, their visibility, and the lack of private investment (compared with alternative suppression measures) emerge as serious constraints. Failure to appreciate the true nature of genetic approaches, such as the SIT, may pose a significant constraint to the wider adoption of the SIT and other genetically-based tactics, e.g. transgenic genetically modified organisms (GMOs). Lack of support for the necessary underpinning strategic research also appears to be an important constraint. Hence the case for extensive strategic research in ecology, population dynamics, genetics, and insect behaviour and nutrition is a compelling one. Raising the competitiveness of released sterile males remains the major research objective of the SIT. (author)
International Nuclear Information System (INIS)
Heilbron Filho, Paulo Fernando Lavalle; Xavier, Ana Maria
2005-01-01
The revision process of the international radiological protection regulations has resulted in the adoption of new concepts, such as practice, intervention, avoidable and restriction of dose (dose constraint). The latter deserving of special mention since it may involve reducing a priori of the dose limits established both for the public and to individuals occupationally exposed, values that can be further reduced, depending on the application of the principle of optimization. This article aims to present, with clarity, from the criteria adopted to define dose constraint values to the public, a methodology to establish the dose constraint values for occupationally exposed individuals, as well as an example of the application of this methodology to the practice of industrial radiography
Psychological constraints on egalitarianism
DEFF Research Database (Denmark)
Kasperbauer, Tyler Joshua
2015-01-01
processes motivating people to resist various aspects of egalitarianism. I argue for two theses, one normative and one descriptive. The normative thesis holds that egalitarians must take psychological constraints into account when constructing egalitarian ideals. I draw from non-ideal theories in political...... philosophy, which aim to construct moral goals with current social and political constraints in mind, to argue that human psychology must be part of a non-ideal theory of egalitarianism. The descriptive thesis holds that the most fundamental psychological challenge to egalitarian ideals comes from what......Debates over egalitarianism for the most part are not concerned with constraints on achieving an egalitarian society, beyond discussions of the deficiencies of egalitarian theory itself. This paper looks beyond objections to egalitarianism as such and investigates the relevant psychological...
Craik, Daniel
2013-01-01
Constraints on the CKM angle \\gamma are presented from GLW, ADS, and GGSZ analyses of B+- -> D K+- at the LHCb experiment. The branching fractions of B0 -> D0bar K+ \\pi- and Bs -> D0bar K- \\pi+ are also reported, measured relative to the related mode B0 -> D0bar \\pi+ \\pi-.
Constraint-based scheduling applying constraint programming to scheduling problems
Baptiste, Philippe; Nuijten, Wim
2001-01-01
Constraint Programming is a problem-solving paradigm that establishes a clear distinction between two pivotal aspects of a problem: (1) a precise definition of the constraints that define the problem to be solved and (2) the algorithms and heuristics enabling the selection of decisions to solve the problem. It is because of these capabilities that Constraint Programming is increasingly being employed as a problem-solving tool to solve scheduling problems. Hence the development of Constraint-Based Scheduling as a field of study. The aim of this book is to provide an overview of the most widely used Constraint-Based Scheduling techniques. Following the principles of Constraint Programming, the book consists of three distinct parts: The first chapter introduces the basic principles of Constraint Programming and provides a model of the constraints that are the most often encountered in scheduling problems. Chapters 2, 3, 4, and 5 are focused on the propagation of resource constraints, which usually are responsibl...
International Nuclear Information System (INIS)
Alwis, S.P. de
2016-01-01
We discuss constraints on KKLT/KKLMMT and LVS scenarios that use anti-branes to get an uplift to a deSitter vacuum, coming from requiring the validity of an effective field theory description of the physics. We find these are not always satisfied or are hard to satisfy.
Ecosystems emerging. 5: Constraints
Czech Academy of Sciences Publication Activity Database
Patten, B. C.; Straškraba, Milan; Jorgensen, S. E.
2011-01-01
Roč. 222, č. 16 (2011), s. 2945-2972 ISSN 0304-3800 Institutional research plan: CEZ:AV0Z50070508 Keywords : constraint * epistemic * ontic Subject RIV: EH - Ecology, Behaviour Impact factor: 2.326, year: 2011 http://www.sciencedirect.com/science/article/pii/S0304380011002274
DEFF Research Database (Denmark)
Dove, Graham; Biskjær, Michael Mose; Lundqvist, Caroline Emilie
2017-01-01
groups of students building three models each. We studied groups building with traditional plastic bricks and also using a digital environment. The building tasks students undertake, and our subsequent analysis, are informed by the role constraints and ambiguity play in creative processes. Based...
Graphical constraints: a graphical user interface for constraint problems
Vieira, Nelson Manuel Marques
2015-01-01
A constraint satisfaction problem is a classical artificial intelligence paradigm characterized by a set of variables (each variable with an associated domain of possible values), and a set of constraints that specify relations among subsets of these variables. Solutions are assignments of values to all variables that satisfy all the constraints. Many real world problems may be modelled by means of constraints. The range of problems that can use this representation is very diverse and embrace...
Distance Constraint Satisfaction Problems
Bodirsky, Manuel; Dalmau, Victor; Martin, Barnaby; Pinsker, Michael
We study the complexity of constraint satisfaction problems for templates Γ that are first-order definable in ({ Z}; {suc}), the integers with the successor relation. Assuming a widely believed conjecture from finite domain constraint satisfaction (we require the tractability conjecture by Bulatov, Jeavons and Krokhin in the special case of transitive finite templates), we provide a full classification for the case that Γ is locally finite (i.e., the Gaifman graph of Γ has finite degree). We show that one of the following is true: The structure Γ is homomorphically equivalent to a structure with a certain majority polymorphism (which we call modular median) and CSP(Γ) can be solved in polynomial time, or Γ is homomorphically equivalent to a finite transitive structure, or CSP(Γ) is NP-complete.
Zweben, Monte
1993-01-01
The GERRY scheduling system developed by NASA Ames with assistance from the Lockheed Space Operations Company, and the Lockheed Artificial Intelligence Center, uses a method called constraint-based iterative repair. Using this technique, one encodes both hard rules and preference criteria into data structures called constraints. GERRY repeatedly attempts to improve schedules by seeking repairs for violated constraints. The system provides a general scheduling framework which is being tested on two NASA applications. The larger of the two is the Space Shuttle Ground Processing problem which entails the scheduling of all the inspection, repair, and maintenance tasks required to prepare the orbiter for flight. The other application involves power allocation for the NASA Ames wind tunnels. Here the system will be used to schedule wind tunnel tests with the goal of minimizing power costs. In this paper, we describe the GERRY system and its application to the Space Shuttle problem. We also speculate as to how the system would be used for manufacturing, transportation, and military problems.
Directory of Open Access Journals (Sweden)
Eduard Vinyamata
2014-11-01
Full Text Available
«En parlar de les Nacions Unides, ens ve al cap la imatge dels cascos blaus, però les operacions de pau són més complexes i impliquen molta gent: militars, policia, diplomàtics i societat civil.» Ho va afirmar Sally Fegan-Wyles, la subsecretària general de les Nacions Unides i cap de l’Institut de les Nacions Unides per a la Formació Professional i la Recerca (UNITAR, en la inauguració del VII Congrés Internacional de Conflictologia i Pau de la Universitat Oberta de Catalunya (UOC, que va tenir lloc els dies 2 i 3 d’octubre. Aquesta professional del desenvolupament va explicar l’impacte que té la formació sobre resolució de conflictes en el manteniment de la pau i la seguretat al món. En aquest esdeveniment, organitzat pel Campus per la Pau i els Estudis de Dret i Ciència Política de la Universitat Oberta de Catalunya, Sally Fegan-Wyles va destacar el fet que les intervencions de pau que porten a terme les Nacions Unides han canviat de naturalesa, com també ho han fet els conflictes, amb l’aparició de les armes lleugeres i les tàctiques de guerrilla. Segons la directora d’UNITAR, «hem passat de l’acord de pau a un procés multidimensional, que implica tant la societat civil del país en conflicte com el cos diplomàtic i polític, i les tropes militars».
Efficient Searching with Linear Constraints
DEFF Research Database (Denmark)
Agarwal, Pankaj K.; Arge, Lars Allan; Erickson, Jeff
2000-01-01
We show how to preprocess a set S of points in d into an external memory data structure that efficiently supports linear-constraint queries. Each query is in the form of a linear constraint xd a0+∑d−1i=1 aixi; the data structure must report all the points of S that satisfy the constraint. This pr...
Deepening Contractions and Collateral Constraints
DEFF Research Database (Denmark)
Jensen, Henrik; Ravn, Søren Hove; Santoro, Emiliano
and occasionally non-binding credit constraints. Easier credit access increases the likelihood that constraints become slack in the face of expansionary shocks, while contractionary shocks are further amplified due to tighter constraints. As a result, busts gradually become deeper than booms. Based...
Constraints on γ and strong phases from B → πK decays
International Nuclear Information System (INIS)
Buras, Andrzej J.; Fleischer, Robert
2001-01-01
As we pointed out recently, the neutral decays B d → π - + K± and B d → π 0 K may provide non-trivial bounds on the CKM angle γ. Here we reconsider this approach in the light of recent CLEO data, which look very interesting. In particular, the results for the corresponding CP-averaged branching ratios are in favour of strong constraints on γ, where the second quadrant is preferred. Such a situation would be in conflict with the standard analysis of the unitarity triangle. Moreover, constraints on a CO-conserving strong phase δ n are in favour of a negative value of cosδ n , which would be in conflict with the factorization expectation. In addition, there seems to be an interesting discrepancy with the bounds that are implied by the charged B → πK system: whereas these decays favour a range for γ that is similar to that of the neutral modes, they point towards a positive value of cosδ c , which would be in conflict with the expectation of equal signs for cosδ n and cosδ c . (author)
Constraints on γ and strong phases from B → πK decays
International Nuclear Information System (INIS)
Buras, A.J.
2000-08-01
As we pointed out recently, the neutral decays B d → π -+ K ± and B d → π 0 K may provide non-trivial bounds on the CKM angle γ. Here we reconsider this approach in the light of recent CLEO data, which look very interesting. In particular, the results for the corresponding CP-averaged branching ratios are in favour of strong constraints on γ, where the second quadrant is preferred. Such a situation would be in conflict with the standard analysis of the unitarity triangle. Moreover, constraints on a CP-conserving strong phase δ n are in favour of a negative value of cos δ n , which would be in conflict with the factorization expectation. In addition, there seems to be an interesting discrepancy with the bounds that are implied by the charged B → π K system: whereas these decays favour a range for γ that is similar to that of the neutral modes, they point towards a positive value of cos δ c , which would be in conflict with the expectation of equal signs for cos δ n and cos δ c . (orig.)
Design with Nonlinear Constraints
Tang, Chengcheng
2015-12-10
Most modern industrial and architectural designs need to satisfy the requirements of their targeted performance and respect the limitations of available fabrication technologies. At the same time, they should reflect the artistic considerations and personal taste of the designers, which cannot be simply formulated as optimization goals with single best solutions. This thesis aims at a general, flexible yet e cient computational framework for interactive creation, exploration and discovery of serviceable, constructible, and stylish designs. By formulating nonlinear engineering considerations as linear or quadratic expressions by introducing auxiliary variables, the constrained space could be e ciently accessed by the proposed algorithm Guided Projection, with the guidance of aesthetic formulations. The approach is introduced through applications in different scenarios, its effectiveness is demonstrated by examples that were difficult or even impossible to be computationally designed before. The first application is the design of meshes under both geometric and static constraints, including self-supporting polyhedral meshes that are not height fields. Then, with a formulation bridging mesh based and spline based representations, the application is extended to developable surfaces including origami with curved creases. Finally, general approaches to extend hard constraints and soft energies are discussed, followed by a concluding remark outlooking possible future studies.
Searching for genomic constraints
Energy Technology Data Exchange (ETDEWEB)
Lio` , P [Cambridge, Univ. (United Kingdom). Genetics Dept.; Ruffo, S [Florence, Univ. (Italy). Fac. di Ingegneria. Dipt. di Energetica ` S. Stecco`
1998-01-01
The authors have analyzed general properties of very long DNA sequences belonging to simple and complex organisms, by using different correlation methods. They have distinguished those base compositional rules that concern the entire genome which they call `genomic constraints` from the rules that depend on the `external natural selection` acting on single genes, i. e. protein-centered constraints. They show that G + C content, purine / pyrimidine distributions and biological complexity of the organism are the most important factors which determine base compositional rules and genome complexity. Three main facts are here reported: bacteria with high G + C content have more restrictions on base composition than those with low G + C content; at constant G + C content more complex organisms, ranging from prokaryotes to higher eukaryotes (e.g. human) display an increase of repeats 10-20 nucleotides long, which are also partly responsible for long-range correlations; work selection of length 3 to 10 is stronger in human and in bacteria for two distinct reasons. With respect to previous studies, they have also compared the genomic sequence of the archeon Methanococcus jannaschii with those of bacteria and eukaryotes: it shows sometimes an intermediate statistical behaviour.
Searching for genomic constraints
International Nuclear Information System (INIS)
Lio', P.; Ruffo, S.
1998-01-01
The authors have analyzed general properties of very long DNA sequences belonging to simple and complex organisms, by using different correlation methods. They have distinguished those base compositional rules that concern the entire genome which they call 'genomic constraints' from the rules that depend on the 'external natural selection' acting on single genes, i. e. protein-centered constraints. They show that G + C content, purine / pyrimidine distributions and biological complexity of the organism are the most important factors which determine base compositional rules and genome complexity. Three main facts are here reported: bacteria with high G + C content have more restrictions on base composition than those with low G + C content; at constant G + C content more complex organisms, ranging from prokaryotes to higher eukaryotes (e.g. human) display an increase of repeats 10-20 nucleotides long, which are also partly responsible for long-range correlations; work selection of length 3 to 10 is stronger in human and in bacteria for two distinct reasons. With respect to previous studies, they have also compared the genomic sequence of the archeon Methanococcus jannaschii with those of bacteria and eukaryotes: it shows sometimes an intermediate statistical behaviour
Supergravity constraints on monojets
International Nuclear Information System (INIS)
Nandi, S.
1986-01-01
In the standard model, supplemented by N = 1 minimal supergravity, all the supersymmetric particle masses can be expressed in terms of a few unknown parameters. The resulting mass relations, and the laboratory and the cosmological bounds on these superpartner masses are used to put constraints on the supersymmetric origin of the CERN monojets. The latest MAC data at PEP excludes the scalar quarks, of masses up to 45 GeV, as the origin of these monojets. The cosmological bounds, for a stable photino, excludes the mass range necessary for the light gluino-heavy squark production interpretation. These difficulties can be avoided by going beyond the minimal supergravity theory. Irrespective of the monojets, the importance of the stable γ as the source of the cosmological dark matter is emphasized
Temporal Concurrent Constraint Programming
DEFF Research Database (Denmark)
Valencia, Frank Dan
Concurrent constraint programming (ccp) is a formalism for concurrency in which agents interact with one another by telling (adding) and asking (reading) information in a shared medium. Temporal ccp extends ccp by allowing agents to be constrained by time conditions. This dissertation studies...... temporal ccp by developing a process calculus called ntcc. The ntcc calculus generalizes the tcc model, the latter being a temporal ccp model for deterministic and synchronouss timed reactive systems. The calculus is built upon few basic ideas but it captures several aspects of timed systems. As tcc, ntcc...... structures, robotic devises, multi-agent systems and music applications. The calculus is provided with a denotational semantics that captures the reactive computations of processes in the presence of arbitrary environments. The denotation is proven to be fully-abstract for a substantial fragment...
Minimal Flavor Constraints for Technicolor
DEFF Research Database (Denmark)
Sakuma, Hidenori; Sannino, Francesco
2010-01-01
We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self-coupling and mas......We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self...
Social Constraints on Animate Vision
National Research Council Canada - National Science Library
Breazeal, Cynthia; Edsinger, Aaron; Fitzpatrick, Paul; Scassellati, Brian
2000-01-01
.... In humanoid robotic systems, or in any animate vision system that interacts with people, social dynamics provide additional levels of constraint and provide additional opportunities for processing economy...
Modifier constraint in alkali borophosphate glasses using topological constraint theory
Energy Technology Data Exchange (ETDEWEB)
Li, Xiang [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zeng, Huidan, E-mail: hdzeng@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Jiang, Qi [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhao, Donghui [Unifrax Corporation, Niagara Falls, NY 14305 (United States); Chen, Guorong [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Wang, Zhaofeng; Sun, Luyi [Department of Chemical & Biomolecular Engineering and Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269 (United States); Chen, Jianding [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)
2016-12-01
In recent years, composition-dependent properties of glasses have been successfully predicted using the topological constraint theory. The constraints of the glass network are derived from two main parts: network formers and network modifiers. The constraints of the network formers can be calculated on the basis of the topological structure of the glass. However, the latter cannot be accurately calculated in this way, because of the existing of ionic bonds. In this paper, the constraints of the modifier ions in phosphate glasses were thoroughly investigated using the topological constraint theory. The results show that the constraints of the modifier ions are gradually increased with the addition of alkali oxides. Furthermore, an improved topological constraint theory for borophosphate glasses is proposed by taking the composition-dependent constraints of the network modifiers into consideration. The proposed theory is subsequently evaluated by analyzing the composition dependence of the glass transition temperature in alkali borophosphate glasses. This method is supposed to be extended to other similar glass systems containing alkali ions.
Seismological Constraints on Geodynamics
Lomnitz, C.
2004-12-01
Earth is an open thermodynamic system radiating heat energy into space. A transition from geostatic earth models such as PREM to geodynamical models is needed. We discuss possible thermodynamic constraints on the variables that govern the distribution of forces and flows in the deep Earth. In this paper we assume that the temperature distribution is time-invariant, so that all flows vanish at steady state except for the heat flow Jq per unit area (Kuiken, 1994). Superscript 0 will refer to the steady state while x denotes the excited state of the system. We may write σ 0=(J{q}0ṡX{q}0)/T where Xq is the conjugate force corresponding to Jq, and σ is the rate of entropy production per unit volume. Consider now what happens after the occurrence of an earthquake at time t=0 and location (0,0,0). The earthquake introduces a stress drop Δ P(x,y,z) at all points of the system. Response flows are directed along the gradients toward the epicentral area, and the entropy production will increase with time as (Prigogine, 1947) σ x(t)=σ 0+α {1}/(t+β )+α {2}/(t+β )2+etc A seismological constraint on the parameters may be obtained from Omori's empirical relation N(t)=p/(t+q) where N(t) is the number of aftershocks at time t following the main shock. It may be assumed that p/q\\sim\\alpha_{1}/\\beta times a constant. Another useful constraint is the Mexican-hat geometry of the seismic transient as obtained e.g. from InSAR radar interferometry. For strike-slip events such as Landers the distribution of \\DeltaP is quadrantal, and an oval-shaped seismicity gap develops about the epicenter. A weak outer triggering maxiμm is found at a distance of about 17 fault lengths. Such patterns may be extracted from earthquake catalogs by statistical analysis (Lomnitz, 1996). Finally, the energy of the perturbation must be at least equal to the recovery energy. The total energy expended in an aftershock sequence can be found approximately by integrating the local contribution over
Observational constraints on interstellar chemistry
International Nuclear Information System (INIS)
Winnewisser, G.
1984-01-01
The author points out presently existing observational constraints in the detection of interstellar molecular species and the limits they may cast on our knowledge of interstellar chemistry. The constraints which arise from the molecular side are summarised and some technical difficulties encountered in detecting new species are discussed. Some implications for our understanding of molecular formation processes are considered. (Auth.)
Market segmentation using perceived constraints
Jinhee Jun; Gerard Kyle; Andrew Mowen
2008-01-01
We examined the practical utility of segmenting potential visitors to Cleveland Metroparks using their constraint profiles. Our analysis identified three segments based on their scores on the dimensions of constraints: Other priorities--visitors who scored the highest on 'other priorities' dimension; Highly Constrained--visitors who scored relatively high on...
Fixed Costs and Hours Constraints
Johnson, William R.
2011-01-01
Hours constraints are typically identified by worker responses to questions asking whether they would prefer a job with more hours and more pay or fewer hours and less pay. Because jobs with different hours but the same rate of pay may be infeasible when there are fixed costs of employment or mandatory overtime premia, the constraint in those…
An Introduction to 'Creativity Constraints'
DEFF Research Database (Denmark)
Onarheim, Balder; Biskjær, Michael Mose
2013-01-01
Constraints play a vital role as both restrainers and enablers in innovation processes by governing what the creative agent/s can and cannot do, and what the output can and cannot be. Notions of constraints are common in creativity research, but current contributions are highly dispersed due to n...
Constraint Programming for Context Comprehension
DEFF Research Database (Denmark)
Christiansen, Henning
2014-01-01
A close similarity is demonstrated between context comprehension, such as discourse analysis, and constraint programming. The constraint store takes the role of a growing knowledge base learned throughout the discourse, and a suitable con- straint solver does the job of incorporating new pieces...
Vocabulary Constraint on Texts
Directory of Open Access Journals (Sweden)
C. Sutarsyah
2008-01-01
Full Text Available This case study was carried out in the English Education Department of State University of Malang. The aim of the study was to identify and describe the vocabulary in the reading text and to seek if the text is useful for reading skill development. A descriptive qualitative design was applied to obtain the data. For this purpose, some available computer programs were used to find the description of vocabulary in the texts. It was found that the 20 texts containing 7,945 words are dominated by low frequency words which account for 16.97% of the words in the texts. The high frequency words occurring in the texts were dominated by function words. In the case of word levels, it was found that the texts have very limited number of words from GSL (General Service List of English Words (West, 1953. The proportion of the first 1,000 words of GSL only accounts for 44.6%. The data also show that the texts contain too large proportion of words which are not in the three levels (the first 2,000 and UWL. These words account for 26.44% of the running words in the texts.Â It is believed that the constraints are due to the selection of the texts which are made of a series of short-unrelated texts. This kind of text is subject to the accumulation of low frequency words especially those of content words and limited of words from GSL. It could also defeat the development of students' reading skills and vocabulary enrichment.
Constraints on WIMP masses and interactions
International Nuclear Information System (INIS)
Enqvist, K.
1991-01-01
It is shown that cosmology, experiments and unitarity considerations limit the mass and coupling g' of a generic, heavy WIMP from the above as well as from the below. There are absolute lower limits of 4x10 -5 g and 6x10 -5 g for the couplings of Diracn and Majorana WIMPs, respectively. In U(1)' models cosmology implies an upper limit of about 1 TeV on the Z' and on the WIMP masses, but only in the absence of Z-Z' mixing. (orig.)
Machine tongues. X. Constraint languages
Energy Technology Data Exchange (ETDEWEB)
Levitt, D.
Constraint languages and programming environments will help the designer produce a lucid description of a problem domain, and then of particular situations and problems in it. Early versions of these languages were given descriptions of real world domain constraints, like the operation of electrical and mechanical parts. More recently, the author has automated a vocabulary for describing musical jazz phrases, using constraint language as a jazz improviser. General constraint languages will handle all of these domains. Once the model is in place, the system will connect built-in code fragments and algorithms to answer questions about situations; that is, to help solve problems. Bugs will surface not in code, but in designs themselves. 15 references.
Fluid convection, constraint and causation
Bishop, Robert C.
2012-01-01
Complexity—nonlinear dynamics for my purposes in this essay—is rich with metaphysical and epistemological implications but is receiving sustained philosophical analysis only recently. I will explore some of the subtleties of causation and constraint in Rayleigh–Bénard convection as an example of a complex phenomenon, and extract some lessons for further philosophical reflection on top-down constraint and causation particularly with respect to causal foundationalism. PMID:23386955
Developmental constraints on behavioural flexibility.
Holekamp, Kay E; Swanson, Eli M; Van Meter, Page E
2013-05-19
We suggest that variation in mammalian behavioural flexibility not accounted for by current socioecological models may be explained in part by developmental constraints. From our own work, we provide examples of constraints affecting variation in behavioural flexibility, not only among individuals, but also among species and higher taxonomic units. We first implicate organizational maternal effects of androgens in shaping individual differences in aggressive behaviour emitted by female spotted hyaenas throughout the lifespan. We then compare carnivores and primates with respect to their locomotor and craniofacial adaptations. We inquire whether antagonistic selection pressures on the skull might impose differential functional constraints on evolvability of skulls and brains in these two orders, thus ultimately affecting behavioural flexibility in each group. We suggest that, even when carnivores and primates would theoretically benefit from the same adaptations with respect to behavioural flexibility, carnivores may nevertheless exhibit less behavioural flexibility than primates because of constraints imposed by past adaptations in the morphology of the limbs and skull. Phylogenetic analysis consistent with this idea suggests greater evolutionary lability in relative brain size within families of primates than carnivores. Thus, consideration of developmental constraints may help elucidate variation in mammalian behavioural flexibility.
Data assimilation with inequality constraints
Thacker, W. C.
If values of variables in a numerical model are limited to specified ranges, these restrictions should be enforced when data are assimilated. The simplest option is to assimilate without regard for constraints and then to correct any violations without worrying about additional corrections implied by correlated errors. This paper addresses the incorporation of inequality constraints into the standard variational framework of optimal interpolation with emphasis on our limited knowledge of the underlying probability distributions. Simple examples involving only two or three variables are used to illustrate graphically how active constraints can be treated as error-free data when background errors obey a truncated multi-normal distribution. Using Lagrange multipliers, the formalism is expanded to encompass the active constraints. Two algorithms are presented, both relying on a solution ignoring the inequality constraints to discover violations to be enforced. While explicitly enforcing a subset can, via correlations, correct the others, pragmatism based on our poor knowledge of the underlying probability distributions suggests the expedient of enforcing them all explicitly to avoid the computationally expensive task of determining the minimum active set. If additional violations are encountered with these solutions, the process can be repeated. Simple examples are used to illustrate the algorithms and to examine the nature of the corrections implied by correlated errors.
Constraint programming and decision making
Kreinovich, Vladik
2014-01-01
In many application areas, it is necessary to make effective decisions under constraints. Several area-specific techniques are known for such decision problems; however, because these techniques are area-specific, it is not easy to apply each technique to other applications areas. Cross-fertilization between different application areas is one of the main objectives of the annual International Workshops on Constraint Programming and Decision Making. Those workshops, held in the US (El Paso, Texas), in Europe (Lyon, France), and in Asia (Novosibirsk, Russia), from 2008 to 2012, have attracted researchers and practitioners from all over the world. This volume presents extended versions of selected papers from those workshops. These papers deal with all stages of decision making under constraints: (1) formulating the problem of multi-criteria decision making in precise terms, (2) determining when the corresponding decision problem is algorithmically solvable; (3) finding the corresponding algorithms, and making...
Universal Unitarity Triangle 2016 and the tension between ΔM{sub s,d} and ε{sub K} in CMFV models
Energy Technology Data Exchange (ETDEWEB)
Blanke, Monika [Karlsruhe Institute of Technology, Institut fur Kernphysik, Eggenstein-Leopoldshafen (Germany); Karlsruhe Institute of Technology, Institut fur Theoretische Teilchenphysik, Karlsruhe (Germany); Buras, Andrzej J. [TUM-IAS, Garching (Germany); TUM, Physik Department, Garching (Germany)
2016-04-15
Motivated by the recently improved results from the Fermilab Lattice and MILC Collaborations on the hadronic matrix elements entering ΔM{sub s,d} in B{sup 0}{sub s,d}- anti B{sup 0}{sub s,d} mixing, we determine the universal unitarity triangle (UUT) in models with constrained minimal flavour violation (CMFV). Of particular importance are the very precise determinations of the ratio vertical stroke V{sub ub} vertical stroke / vertical stroke V{sub cb} vertical stroke = 0.0864 ± 0.0025 and of the angle γ = (62.7 ± 2.1) {sup circle}. They follow in this framework from the experimental values of ΔM{sub d}/ΔM{sub s} and of the CP-asymmetry S{sub ψK{sub S}}. As in CMFV models the new contributions to meson mixings can be described by a single flavour-universal variable S(v), we next determine the CKM matrix elements vertical stroke V{sub ts} vertical stroke, vertical stroke V{sub td} vertical stroke, vertical stroke V{sub cb} vertical stroke and vertical stroke V{sub ub} vertical stroke as functions of S(v) using the experimental value of ΔM{sub s} as input. The lower bound on S(v) in these models, derived by us in 2006, implies then upper bounds on these four CKM elements and on the CP-violating parameter ε{sub K}, which turns out to be significantly below its experimental value. This strategy avoids the use of tree-level determinations of vertical stroke V{sub ub} vertical stroke and vertical stroke V{sub cb} vertical stroke, which are presently subject to considerable uncertainties. On the other hand, if ε{sub K} is used instead of ΔM{sub s} as input, ΔM{sub s,d} are found to be significantly above the data. In this manner we point out that the new lattice data have significantly sharpened the tension between ΔM{sub s,d} and ε{sub K} within the CMFV framework. This implies the presence of new physics contributions beyond this framework that are responsible for the breakdown of the flavour universality of the function S(v). We also present the
Constraint elimination in dynamical systems
Singh, R. P.; Likins, P. W.
1989-01-01
Large space structures (LSSs) and other dynamical systems of current interest are often extremely complex assemblies of rigid and flexible bodies subjected to kinematical constraints. A formulation is presented for the governing equations of constrained multibody systems via the application of singular value decomposition (SVD). The resulting equations of motion are shown to be of minimum dimension.
Constraint Programming versus Mathematical Programming
DEFF Research Database (Denmark)
Hansen, Jesper
2003-01-01
Constraint Logic Programming (CLP) is a relatively new technique from the 80's with origins in Computer Science and Artificial Intelligence. Lately, much research have been focused on ways of using CLP within the paradigm of Operations Research (OR) and vice versa. The purpose of this paper...
Sterile neutrino constraints from cosmology
DEFF Research Database (Denmark)
Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.
2012-01-01
The presence of light particles beyond the standard model's three neutrino species can profoundly impact the physics of decoupling and primordial nucleosynthesis. I review the observational signatures of extra light species, present constraints from recent data, and discuss the implications of po...... of possible sterile neutrinos with O(eV)-masses for cosmology....
Intertemporal consumption and credit constraints
DEFF Research Database (Denmark)
Leth-Petersen, Søren
2010-01-01
There is continuing controversy over the importance of credit constraints. This paper investigates whether total household expenditure and debt is affected by an exogenous increase in access to credit provided by a credit market reform that enabled Danish house owners to use housing equity...
Financial Constraints: Explaining Your Position.
Cargill, Jennifer
1988-01-01
Discusses the importance of educating library patrons about the library's finances and the impact of budget constraints and the escalating cost of serials on materials acquisition. Steps that can be taken in educating patrons by interpreting and publicizing financial information are suggested. (MES)
Creativity from Constraints in Engineering Design
DEFF Research Database (Denmark)
Onarheim, Balder
2012-01-01
This paper investigates the role of constraints in limiting and enhancing creativity in engineering design. Based on a review of literature relating constraints to creativity, the paper presents a longitudinal participatory study from Coloplast A/S, a major international producer of disposable...... and ownership of formal constraints played a crucial role in defining their influence on creativity – along with the tacit constraints held by the designers. The designers were found to be highly constraint focused, and four main creative strategies for constraint manipulation were observed: blackboxing...
A compendium of chameleon constraints
International Nuclear Information System (INIS)
Burrage, Clare; Sakstein, Jeremy
2016-01-01
The chameleon model is a scalar field theory with a screening mechanism that explains how a cosmologically relevant light scalar can avoid the constraints of intra-solar-system searches for fifth-forces. The chameleon is a popular dark energy candidate and also arises in f ( R ) theories of gravity. Whilst the chameleon is designed to avoid historical searches for fifth-forces it is not unobservable and much effort has gone into identifying the best observables and experiments to detect it. These results are not always presented for the same models or in the same language, a particular problem when comparing astrophysical and laboratory searches making it difficult to understand what regions of parameter space remain. Here we present combined constraints on the chameleon model from astrophysical and laboratory searches for the first time and identify the remaining windows of parameter space. We discuss the implications for cosmological chameleon searches and future small-scale probes.
A compendium of chameleon constraints
Energy Technology Data Exchange (ETDEWEB)
Burrage, Clare [School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Sakstein, Jeremy, E-mail: clare.burrage@nottingham.ac.uk, E-mail: jeremy.sakstein@port.ac.uk [Center for Particle Cosmology, Department of Physics and Astronomy, University of Pennsylvania, 209 S. 33rd St., Philadelphia, PA 19104 (United States)
2016-11-01
The chameleon model is a scalar field theory with a screening mechanism that explains how a cosmologically relevant light scalar can avoid the constraints of intra-solar-system searches for fifth-forces. The chameleon is a popular dark energy candidate and also arises in f ( R ) theories of gravity. Whilst the chameleon is designed to avoid historical searches for fifth-forces it is not unobservable and much effort has gone into identifying the best observables and experiments to detect it. These results are not always presented for the same models or in the same language, a particular problem when comparing astrophysical and laboratory searches making it difficult to understand what regions of parameter space remain. Here we present combined constraints on the chameleon model from astrophysical and laboratory searches for the first time and identify the remaining windows of parameter space. We discuss the implications for cosmological chameleon searches and future small-scale probes.
Self-Imposed Creativity Constraints
DEFF Research Database (Denmark)
Biskjaer, Michael Mose
2013-01-01
Abstract This dissertation epitomizes three years of research guided by the research question: how can we conceptualize creative self-binding as a resource in art and design processes? Concretely, the dissertation seeks to offer insight into the puzzling observation that highly skilled creative...... practitioners sometimes freely and intentionally impose rigid rules, peculiar principles, and other kinds of creative obstructions on themselves as a means to spur momentum in the process and reach a distinctly original outcome. To investigate this the dissertation is composed of four papers (Part II) framed...... of analysis. Informed by the insight that constraints both enable and restrain creative agency, the dissertation’s main contention is that creative self- binding may profitably be conceptualized as the exercise of self-imposed creativity constraints. Thus, the dissertation marks an analytical move from vague...
Macroscopic constraints on string unification
International Nuclear Information System (INIS)
Taylor, T.R.
1989-03-01
The comparison of sting theory with experiment requires a huge extrapolation from the microscopic distances, of order of the Planck length, up to the macroscopic laboratory distances. The quantum effects give rise to large corrections to the macroscopic predictions of sting unification. I discus the model-independent constraints on the gravitational sector of string theory due to the inevitable existence of universal Fradkin-Tseytlin dilatons. 9 refs
Financial Constraints and Franchising Decisions
Kai-Uwe Kuhn; Francine Lafontaine; Ying Fan
2013-01-01
We study how the financial constraints of agents affect the behavior of principals in the context of franchising. We develop an empirical model of franchising starting with a principal-agent framework that emphasizes the role of franchisees' collateral from an incentive perspective. We estimate the determinants of chains' entry (into franchising) and growth decisions using data on franchised chains and data on local macroeconomic conditions. In particular, we use collateralizable housing weal...
Analysis of Space Tourism Constraints
Bonnal, Christophe
2002-01-01
Space tourism appears today as a new Eldorado in a relatively near future. Private operators are already proposing services for leisure trips in Low Earth Orbit, and some happy few even tested them. But are these exceptional events really marking the dawn of a new space age ? The constraints associated to the space tourism are severe : - the economical balance of space tourism is tricky; development costs of large manned - the technical definition of such large vehicles is challenging, mainly when considering - the physiological aptitude of passengers will have a major impact on the mission - the orbital environment will also lead to mission constraints on aspects such as radiation, However, these constraints never appear as show-stoppers and have to be dealt with pragmatically: - what are the recommendations one can make for future research in the field of space - which typical roadmap shall one consider to develop realistically this new market ? - what are the synergies with the conventional missions and with the existing infrastructure, - how can a phased development start soon ? The paper proposes hints aiming at improving the credibility of Space Tourism and describes the orientations to follow in order to solve the major hurdles found in such an exciting development.
Infrared Constraint on Ultraviolet Theories
Energy Technology Data Exchange (ETDEWEB)
Tsai, Yuhsin [Cornell Univ., Ithaca, NY (United States)
2012-08-01
While our current paradigm of particle physics, the Standard Model (SM), has been extremely successful at explaining experiments, it is theoretically incomplete and must be embedded into a larger framework. In this thesis, we review the main motivations for theories beyond the SM (BSM) and the ways such theories can be constrained using low energy physics. The hierarchy problem, neutrino mass and the existence of dark matter (DM) are the main reasons why the SM is incomplete . Two of the most plausible theories that may solve the hierarchy problem are the Randall-Sundrum (RS) models and supersymmetry (SUSY). RS models usually suffer from strong flavor constraints, while SUSY models produce extra degrees of freedom that need to be hidden from current experiments. To show the importance of infrared (IR) physics constraints, we discuss the flavor bounds on the anarchic RS model in both the lepton and quark sectors. For SUSY models, we discuss the difficulties in obtaining a phenomenologically allowed gaugino mass, its relation to R-symmetry breaking, and how to build a model that avoids this problem. For the neutrino mass problem, we discuss the idea of generating small neutrino masses using compositeness. By requiring successful leptogenesis and the existence of warm dark matter (WDM), we can set various constraints on the hidden composite sector. Finally, to give an example of model independent bounds from collider experiments, we show how to constrain the DM–SM particle interactions using collider results with an effective coupling description.
Isocurvature constraints on portal couplings
Energy Technology Data Exchange (ETDEWEB)
Kainulainen, Kimmo; Nurmi, Sami; Vaskonen, Ville [Department of Physics, University of Jyväskylä, P.O.Box 35 (YFL), FI-40014 University of Jyväskylä (Finland); Tenkanen, Tommi; Tuominen, Kimmo, E-mail: kimmo.kainulainen@jyu.fi, E-mail: sami.t.nurmi@jyu.fi, E-mail: tommi.tenkanen@helsinki.fi, E-mail: kimmo.i.tuominen@helsinki.fi, E-mail: ville.vaskonen@jyu.fi [Department of Physics, University of Helsinki P.O. Box 64, FI-00014, Helsinki (Finland)
2016-06-01
We consider portal models which are ultraweakly coupled with the Standard Model, and confront them with observational constraints on dark matter abundance and isocurvature perturbations. We assume the hidden sector to contain a real singlet scalar s and a sterile neutrino ψ coupled to s via a pseudoscalar Yukawa term. During inflation, a primordial condensate consisting of the singlet scalar s is generated, and its contribution to the isocurvature perturbations is imprinted onto the dark matter abundance. We compute the total dark matter abundance including the contributions from condensate decay and nonthermal production from the Standard Model sector. We then use the Planck limit on isocurvature perturbations to derive a novel constraint connecting dark matter mass and the singlet self coupling with the scale of inflation: m {sub DM}/GeV ∼< 0.2λ{sub s}{sup 3/8} ( H {sub *}/10{sup 11} GeV){sup −3/2}. This constraint is relevant in most portal models ultraweakly coupled with the Standard Model and containing light singlet scalar fields.
Relaxations of semiring constraint satisfaction problems
CSIR Research Space (South Africa)
Leenen, L
2007-03-01
Full Text Available The Semiring Constraint Satisfaction Problem (SCSP) framework is a popular approach for the representation of partial constraint satisfaction problems. In this framework preferences can be associated with tuples of values of the variable domains...
Transmission and capacity pricing and constraints
International Nuclear Information System (INIS)
Fusco, M.
1999-01-01
A series of overhead viewgraphs accompanied this presentation which discussed the following issues regarding the North American electric power industry: (1) capacity pricing transmission constraints, (2) nature of transmission constraints, (3) consequences of transmission constraints, and (4) prices as market evidence. Some solutions suggested for pricing constraints included the development of contingent contracts, back-up power in supply regions, and new line capacity construction. 8 tabs., 20 figs
Ant colony optimization and constraint programming
Solnon, Christine
2013-01-01
Ant colony optimization is a metaheuristic which has been successfully applied to a wide range of combinatorial optimization problems. The author describes this metaheuristic and studies its efficiency for solving some hard combinatorial problems, with a specific focus on constraint programming. The text is organized into three parts. The first part introduces constraint programming, which provides high level features to declaratively model problems by means of constraints. It describes the main existing approaches for solving constraint satisfaction problems, including complete tree search
The Ambiguous Role of Constraints in Creativity
DEFF Research Database (Denmark)
Biskjær, Michael Mose; Onarheim, Balder; Wiltschnig, Stefan
2011-01-01
The relationship between creativity and constraints is often described in the literature either in rather imprecise, general concepts or in relation to very specific domains. Cross-domain and cross-disciplinary takes on how the handling of constraints influences creative activities are rare. In t......-disciplinary research into the ambiguous role of constraints in creativity....
Learning and Parallelization Boost Constraint Search
Yun, Xi
2013-01-01
Constraint satisfaction problems are a powerful way to abstract and represent academic and real-world problems from both artificial intelligence and operations research. A constraint satisfaction problem is typically addressed by a sequential constraint solver running on a single processor. Rather than construct a new, parallel solver, this work…
A general treatment of dynamic integrity constraints
de Brock, EO
This paper introduces a general, set-theoretic model for expressing dynamic integrity constraints, i.e., integrity constraints on the state changes that are allowed in a given state space. In a managerial context, such dynamic integrity constraints can be seen as representations of "real world"
Measurements of direct CP violation and constraints on the CKM triangle in B → K*π decays
Energy Technology Data Exchange (ETDEWEB)
Wagner, Andrew Phillips [Stanford Univ., CA (United States)
2010-02-01
We constrain the apex of the Cabibbo-Kobayashi-Maskawa unitarity triangle with measurements of B → K*π amplitudes from analyses of B^{0} → K^{+}π^{-}π^{0} and B^{0} → KSπ^{+}π^{-} decays. This constraint is consistent with the world average. The B^{0} → K^{+}π^{-}π^{0} decay mode is reconstructed from a sample of 454 million B^{0}$\\bar{B}$ ^{0} events collected by the BABAR detector at SLAC. We measure direct CP violation in B^{0} → K^{*+}π^{-} decays at the level of 3σ when measurements from both B^{0} → K^{+}π^{-}π^{0} and B^{0} → KSπ^{+}π^{-} decays are combined.
Constraint Specialisation in Horn Clause Verification
DEFF Research Database (Denmark)
Kafle, Bishoksan; Gallagher, John Patrick
2015-01-01
We present a method for specialising the constraints in constrained Horn clauses with respect to a goal. We use abstract interpretation to compute a model of a query-answer transformation of a given set of clauses and a goal. The effect is to propagate the constraints from the goal top......-down and propagate answer constraints bottom-up. Our approach does not unfold the clauses at all; we use the constraints from the model to compute a specialised version of each clause in the program. The approach is independent of the abstract domain and the constraints theory underlying the clauses. Experimental...
Constraint specialisation in Horn clause verification
DEFF Research Database (Denmark)
Kafle, Bishoksan; Gallagher, John Patrick
2017-01-01
We present a method for specialising the constraints in constrained Horn clauses with respect to a goal. We use abstract interpretation to compute a model of a query–answer transformed version of a given set of clauses and a goal. The constraints from the model are then used to compute...... a specialised version of each clause. The effect is to propagate the constraints from the goal top-down and propagate answer constraints bottom-up. The specialisation procedure can be repeated to yield further specialisation. The approach is independent of the abstract domain and the constraint theory...
Nuclear energy and external constraints
International Nuclear Information System (INIS)
Lattes, R.; Thiriet, L.
1983-01-01
The structural factors of this crisis probably predominate over factors arising out the economic situation, even if explanations vary in this respect. In this article devoted to nuclear energy, a possible means of Loosering external constraints the current international economic environment is firstly outlined; the context in which the policies of industrialized countries, and therefore that of France, must be developed. An examination of the possible role of energy policies in general and nuclear policies in particular as an instrument of economic policy in providing a partial solution to this crisis, will then enable to quantitatively evaluate the effects of such policies at a national level [fr
Developmental constraint of insect audition
Directory of Open Access Journals (Sweden)
Strauß Johannes
2006-12-01
Full Text Available Abstract Background Insect ears contain very different numbers of sensory cells, from only one sensory cell in some moths to thousands of sensory cells, e.g. in cicadas. These differences still await functional explanation and especially the large numbers in cicadas remain puzzling. Insects of the different orders have distinct developmental sequences for the generation of auditory organs. These sensory cells might have different functions depending on the developmental stages. Here we propose that constraints arising during development are also important for the design of insect ears and might influence cell numbers of the adults. Presentation of the hypothesis We propose that the functional requirements of the subadult stages determine the adult complement of sensory units in the auditory system of cicadas. The hypothetical larval sensory organ should function as a vibration receiver, representing a functional caenogenesis. Testing the hypothesis Experiments at different levels have to be designed to test the hypothesis. Firstly, the neuroanatomy of the larval sense organ should be analyzed to detail. Secondly, the function should be unraveled neurophysiologically and behaviorally. Thirdly, the persistence of the sensory cells and the rebuilding of the sensory organ to the adult should be investigated. Implications of the hypothesis Usually, the evolution of insect ears is viewed with respect to physiological and neuronal mechanisms of sound perception. This view should be extended to the development of sense organs. Functional requirements during postembryonic development may act as constraints for the evolution of adult organs, as exemplified with the auditory system of cicadas.
Thermomechanical constraints and constitutive formulations in thermoelasticity
Directory of Open Access Journals (Sweden)
Baek S.
2003-01-01
Full Text Available We investigate three classes of constraints in a thermoelastic body: (i a deformation-temperature constraint, (ii a deformation-entropy constraint, and (iii a deformation-energy constraint. These constraints are obtained as limits of unconstrained thermoelastic materials and we show that constraints (ii and (iii are equivalent. By using a limiting procedure, we show that for the constraint (i, the entropy plays the role of a Lagrange multiplier while for (ii and (iii, the absolute temperature plays the role of Lagrange multiplier. We further demonstrate that the governing equations for materials subject to constraint (i are identical to those of an unconstrained material whose internal energy is an affine function of the entropy, while those for materials subject to constraints (ii and (iii are identical to those of an unstrained material whose Helmholtz potential is affine in the absolute temperature. Finally, we model the thermoelastic response of a peroxide-cured vulcanizate of natural rubber and show that imposing the constraint in which the volume change depends only on the internal energy leads to very good predictions (compared to experimental results of the stress and temperature response under isothermal and isentropic conditions.
International Nuclear Information System (INIS)
Thieke, Christian; Bortfeld, Thomas; Niemierko, Andrzej; Nill, Simeon
2003-01-01
Optimization algorithms in inverse radiotherapy planning need information about the desired dose distribution. Usually the planner defines physical dose constraints for each structure of the treatment plan, either in form of minimum and maximum doses or as dose-volume constraints. The concept of equivalent uniform dose (EUD) was designed to describe dose distributions with a higher clinical relevance. In this paper, we present a method to consider the EUD as an optimization constraint by using the method of projections onto convex sets (POCS). In each iteration of the optimization loop, for the actual dose distribution of an organ that violates an EUD constraint a new dose distribution is calculated that satisfies the EUD constraint, leading to voxel-based physical dose constraints. The new dose distribution is found by projecting the current one onto the convex set of all dose distributions fulfilling the EUD constraint. The algorithm is easy to integrate into existing inverse planning systems, and it allows the planner to choose between physical and EUD constraints separately for each structure. A clinical case of a head and neck tumor is optimized using three different sets of constraints: physical constraints for all structures, physical constraints for the target and EUD constraints for the organs at risk, and EUD constraints for all structures. The results show that the POCS method converges stable and given EUD constraints are reached closely
Metric approach to quantum constraints
International Nuclear Information System (INIS)
Brody, Dorje C; Hughston, Lane P; Gustavsson, Anna C T
2009-01-01
A framework for deriving equations of motion for constrained quantum systems is introduced and a procedure for its implementation is outlined. In special cases, the proposed new method, which takes advantage of the fact that the space of pure states in quantum mechanics has both a symplectic structure and a metric structure, reduces to a quantum analogue of the Dirac theory of constraints in classical mechanics. Explicit examples involving spin-1/2 particles are worked out in detail: in the first example, our approach coincides with a quantum version of the Dirac formalism, while the second example illustrates how a situation that cannot be treated by Dirac's approach can nevertheless be dealt with in the present scheme.
Cosmographic Constraints and Cosmic Fluids
Directory of Open Access Journals (Sweden)
Salvatore Capozziello
2013-12-01
Full Text Available The problem of reproducing dark energy effects is reviewed here with particular interest devoted to cosmography. We summarize some of the most relevant cosmological models, based on the assumption that the corresponding barotropic equations of state evolve as the universe expands, giving rise to the accelerated expansion. We describe in detail the ΛCDM (Λ-Cold Dark Matter and ωCDM models, considering also some specific examples, e.g., Chevallier–Polarsky–Linder, the Chaplygin gas and the Dvali–Gabadadze–Porrati cosmological model. Finally, we consider the cosmological consequences of f(R and f(T gravities and their impact on the framework of cosmography. Keeping these considerations in mind, we point out the model-independent procedure related to cosmography, showing how to match the series of cosmological observables to the free parameters of each model. We critically discuss the role played by cosmography, as a selection criterion to check whether a particular model passes or does not present cosmological constraints. In so doing, we find out cosmological bounds by fitting the luminosity distance expansion of the redshift, z, adopting the recent Union 2.1 dataset of supernovae, combined with the baryonic acoustic oscillation and the cosmic microwave background measurements. We perform cosmographic analyses, imposing different priors on the Hubble rate present value. In addition, we compare our results with recent PLANCK limits, showing that the ΛCDM and ωCDM models seem to be the favorite with respect to other dark energy models. However, we show that cosmographic constraints on f(R and f(T cannot discriminate between extensions of General Relativity and dark energy models, leading to a disadvantageous degeneracy problem.
Causality Constraints in Conformal Field Theory
CERN. Geneva
2015-01-01
Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In d-dimensional conformal field theory, we show how such constraints are encoded in crossing symmetry of Euclidean correlators, and derive analogous constraints directly from the conformal bootstrap (analytically). The bootstrap setup is a Lorentzian four-point function corresponding to propagation through a shockwave. Crossing symmetry fixes the signs of certain log terms that appear in the conformal block expansion, which constrains the interactions of low-lying operators. As an application, we use the bootstrap to rederive the well known sign constraint on the (∂φ)4 coupling in effective field theory, from a dual CFT. We also find constraints on theories with higher spin conserved currents. Our analysis is restricted to scalar correlators, but we argue that similar methods should also impose nontrivial constraints on the interactions of spinni...
Constraint Embedding for Multibody System Dynamics
Jain, Abhinandan
2009-01-01
This paper describes a constraint embedding approach for the handling of local closure constraints in multibody system dynamics. The approach uses spatial operator techniques to eliminate local-loop constraints from the system and effectively convert the system into tree-topology systems. This approach allows the direct derivation of recursive O(N) techniques for solving the system dynamics and avoiding the expensive steps that would otherwise be required for handling the closedchain dynamics. The approach is very effective for systems where the constraints are confined to small-subgraphs within the system topology. The paper provides background on the spatial operator O(N) algorithms, the extensions for handling embedded constraints, and concludes with some examples of such constraints.
Use of dose constraints in public exposure
International Nuclear Information System (INIS)
Tageldein, Amged
2015-02-01
An overview of the dose constraints in public exposures has been carried out in this project. The establishment, development and the application of the concept of dose constraints are reviewed with regards to public exposure. The role of dose constraints in the process of optimization of radiation protection was described and has been showed that the concept of the dose constraints along with many other concept of radiation protection is widely applied in the optimization of exposure to radiation. From the beginning of the establishment of dose constraints as a concept in radiation protection, the International Commission of Radiological Protection (ICRP) has published a number of documents that provides detailed application related to radiation protection and safety of public exposure from ionizing radiation. This work provides an overview of such publications and related documents with special emphasis on optimization of public exposure using dose constraints. (au)
Causality constraints in conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Hartman, Thomas; Jain, Sachin; Kundu, Sandipan [Department of Physics, Cornell University,Ithaca, New York (United States)
2016-05-17
Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In d dimensional conformal field theory, we show how such constraints are encoded in crossing symmetry of Euclidean correlators, and derive analogous constraints directly from the conformal bootstrap (analytically). The bootstrap setup is a Lorentzian four-point function corresponding to propagation through a shockwave. Crossing symmetry fixes the signs of certain log terms that appear in the conformal block expansion, which constrains the interactions of low-lying operators. As an application, we use the bootstrap to rederive the well known sign constraint on the (∂ϕ){sup 4} coupling in effective field theory, from a dual CFT. We also find constraints on theories with higher spin conserved currents. Our analysis is restricted to scalar correlators, but we argue that similar methods should also impose nontrivial constraints on the interactions of spinning operators.
Constraint-based Word Segmentation for Chinese
DEFF Research Database (Denmark)
Christiansen, Henning; Bo, Li
2014-01-01
-hoc and statistically based methods. In this paper, we show experiments of implementing different approaches to CWSP in the framework of CHR Grammars [Christiansen, 2005] that provides a constraint solving approach to language analysis. CHR Grammars are based upon Constraint Handling Rules, CHR [Frühwirth, 1998, 2009......], which is a declarative, high-level programming language for specification and implementation of constraint solvers....
Stability Constraints for Robust Model Predictive Control
Directory of Open Access Journals (Sweden)
Amanda G. S. Ottoni
2015-01-01
Full Text Available This paper proposes an approach for the robust stabilization of systems controlled by MPC strategies. Uncertain SISO linear systems with box-bounded parametric uncertainties are considered. The proposed approach delivers some constraints on the control inputs which impose sufficient conditions for the convergence of the system output. These stability constraints can be included in the set of constraints dealt with by existing MPC design strategies, in this way leading to the “robustification” of the MPC.
Some cosmological constraints on gauge theories
International Nuclear Information System (INIS)
Schramm, D.N.
1983-01-01
In these lectures, a review is made of various constraints cosmology may place on gauge theories. Particular emphasis is placed on those constraints obtainable from Big Bang Nucleosynthesis, with only brief mention made of Big Bang Baryosynthesis. There is also a considerable discussion of astrophysical constraints on masses and lifetimes of neutrinos with specific mention of the 'missing mass (light)' problem of galactic dynamics. (orig./HSI)
Generalized Pauli constraints in small atoms
DEFF Research Database (Denmark)
Schilling, Christian; Altunbulak, Murat; Knecht, Stefan
2018-01-01
investigations have found evidence that these constraints are exactly saturated in several physically relevant systems, e.g., in a certain electronic state of the beryllium atom. It has been suggested that, in such cases, the constraints, rather than the details of the Hamiltonian, dictate the system......'s qualitative behavior. Here, we revisit this question with state-of-the-art numerical methods for small atoms. We find that the constraints are, in fact, not exactly saturated, but that they lie much closer to the surface defined by the constraints than the geometry of the problem would suggest. While...
Production Team Maintenance: Systemic Constraints Impacting Implementation
National Research Council Canada - National Science Library
Moore, Terry
1997-01-01
.... Identified constraints included: integrating the PTM positioning strategy into the AMC corporate strategic planning process, manpower modeling simulator limitations, labor force authorizations and decentralization...
Review of Minimal Flavor Constraints for Technicolor
DEFF Research Database (Denmark)
S. Fukano, Hidenori; Sannino, Francesco
2010-01-01
We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self-coupling and mas......We analyze the constraints on the the vacuum polarization of the standard model gauge bosons from a minimal set of flavor observables valid for a general class of models of dynamical electroweak symmetry breaking. We will show that the constraints have a strong impact on the self...
Toward an automaton Constraint for Local Search
Directory of Open Access Journals (Sweden)
Jun He
2009-10-01
Full Text Available We explore the idea of using finite automata to implement new constraints for local search (this is already a successful technique in constraint-based global search. We show how it is possible to maintain incrementally the violations of a constraint and its decision variables from an automaton that describes a ground checker for that constraint. We establish the practicality of our approach idea on real-life personnel rostering problems, and show that it is competitive with the approach of [Pralong, 2007].
Notes on Timed Concurrent Constraint Programming
DEFF Research Database (Denmark)
Nielsen, Mogens; Valencia, Frank D.
2004-01-01
and program reactive systems. This note provides a comprehensive introduction to the background for and central notions from the theory of tccp. Furthermore, it surveys recent results on a particular tccp calculus, ntcc, and it provides a classification of the expressive power of various tccp languages.......A constraint is a piece of (partial) information on the values of the variables of a system. Concurrent constraint programming (ccp) is a model of concurrency in which agents (also called processes) interact by telling and asking information (constraints) to and from a shared store (a constraint...
Optimal Stopping with Information Constraint
International Nuclear Information System (INIS)
Lempa, Jukka
2012-01-01
We study the optimal stopping problem proposed by Dupuis and Wang (Adv. Appl. Probab. 34:141–157, 2002). In this maximization problem of the expected present value of the exercise payoff, the underlying dynamics follow a linear diffusion. The decision maker is not allowed to stop at any time she chooses but rather on the jump times of an independent Poisson process. Dupuis and Wang (Adv. Appl. Probab. 34:141–157, 2002), solve this problem in the case where the underlying is a geometric Brownian motion and the payoff function is of American call option type. In the current study, we propose a mild set of conditions (covering the setup of Dupuis and Wang in Adv. Appl. Probab. 34:141–157, 2002) on both the underlying and the payoff and build and use a Markovian apparatus based on the Bellman principle of optimality to solve the problem under these conditions. We also discuss the interpretation of this model as optimal timing of an irreversible investment decision under an exogenous information constraint.
Linear determining equations for differential constraints
International Nuclear Information System (INIS)
Kaptsov, O V
1998-01-01
A construction of differential constraints compatible with partial differential equations is considered. Certain linear determining equations with parameters are used to find such differential constraints. They generalize the classical determining equations used in the search for admissible Lie operators. As applications of this approach equations of an ideal incompressible fluid and non-linear heat equations are discussed
Optimal Portfolio Choice with Wash Sale Constraints
DEFF Research Database (Denmark)
Astrup Jensen, Bjarne; Marekwica, Marcel
2011-01-01
We analytically solve the portfolio choice problem in the presence of wash sale constraints in a two-period model with one risky asset. Our results show that wash sale constraints can heavily affect portfolio choice of investors with unrealized losses. The trading behavior of such investors...
Freedom and constraint analysis and optimization
Brouwer, Dannis Michel; Boer, Steven; Aarts, Ronald G.K.M.; Meijaard, Jacob Philippus; Jonker, Jan B.
2011-01-01
Many mathematical and intuitive methods for constraint analysis of mechanisms have been proposed. In this article we compare three methods. Method one is based on Grüblers equation. Method two uses an intuitive analysis method based on opening kinematic loops and evaluating the constraints at the
Network Design with Node Degree Balance Constraints
DEFF Research Database (Denmark)
Pedersen, Michael Berliner; Crainic, Teodor Gabriel
This presentation discusses an extension to the network design model where there in addition to the flow conservation constraints also are constraints that require design conservation. This means that the number of arcs entering and leaving a node must be the same. As will be shown the model has ...
Constraint solving for direct manipulation of features
Lourenco, D.; Oliveira, P.; Noort, A.; Bidarra, R.
2006-01-01
In current commercial feature modeling systems, support for direct manipulation of features is not commonly available. This is partly due to the strong reliance of such systems on constraints, but also to the lack of speed of current constraint solvers. In this paper, an approach to the optimization
A Temporal Concurrent Constraint Programming Calculus
DEFF Research Database (Denmark)
Palamidessi, Catuscia; Valencia Posso, Frank Darwin
2001-01-01
The tcc model is a formalism for reactive concurrent constraint programming. In this paper we propose a model of temporal concurrent constraint programming which adds to tcc the capability of modeling asynchronous and non-deterministic timed behavior. We call this tcc extension the ntcc calculus...
Modifier constraints in alkali ultraphosphate glasses
DEFF Research Database (Denmark)
Rodrigues, B.P.; Mauro, J.C.; Yue, Yuanzheng
2014-01-01
In applying the recently introduced concept of cationic constraint strength [J. Chem. Phys. 140, 214501 (2014)] to bond constraint theory (BCT) of binary phosphate glasses in the ultraphosphate region of xR2O-(1-x)P2O5 (with x ≤ 0.5 and R = {Li, Na, Cs}), we demonstrate that a fundamental limitat...
Specifying Dynamic and Deontic Integrity Constraints
Wieringa, Roelf J.; Meyer, John-Jules; Weigand, Hans
In the dominant view of knowledge bases (KB's), a KB is a set of facts (atomic sentences) and integrity constraints (IC's). An IC is then a sentence which must at least be consistent with the other sentences in the KB, This view obliterates the distinction between, for example, the constraint that
Solar system constraints on disformal gravity theories
International Nuclear Information System (INIS)
Ip, Hiu Yan; Schmidt, Fabian; Sakstein, Jeremy
2015-01-01
Disformal theories of gravity are scalar-tensor theories where the scalar couples derivatively to matter via the Jordan frame metric. These models have recently attracted interest in the cosmological context since they admit accelerating solutions. We derive the solution for a static isolated mass in generic disformal gravity theories and transform it into the parameterised post-Newtonian form. This allows us to investigate constraints placed on such theories by local tests of gravity. The tightest constraints come from preferred-frame effects due to the motion of the Solar System with respect to the evolving cosmological background field. The constraints we obtain improve upon the previous solar system constraints by two orders of magnitude, and constrain the scale of the disformal coupling for generic models to ℳ ∼> 100 eV. These constraints render all disformal effects irrelevant for cosmology
Short-sale Constraints and Credit Runs
DEFF Research Database (Denmark)
Venter, Gyuri
), creditors with high private signals are more lenient to roll over debt, and a bank with lower asset quality remains solvent. This leads to higher allocative efficiency in the real economy. My result thus implies that the decrease in average informativeness due to short-sale constraints can be more than......This paper studies how short-sale constraints affect the informational efficiency of market prices and the link between prices and economic activity. I show that under short-sale constraints security prices contain less information. However, short-sale constraints increase the informativeness...... the price of an asset the bank holds. I show that short-selling constraints in the financial market lead to the revival of self-fulfilling beliefs about the beliefs and actions of others, and create multiple equilibria. In the equilibrium where agents rely more on public information (i.e., the price...
Revisiting the simplicity constraints and coherent intertwiners
International Nuclear Information System (INIS)
Dupuis, Maite; Livine, Etera R
2011-01-01
In the context of loop quantum gravity and spinfoam models, the simplicity constraints are essential in that they allow one to write general relativity as a constrained topological BF theory. In this work, we apply the recently developed U(N) framework for SU(2) intertwiners to the issue of imposing the simplicity constraints to spin network states. More particularly, we focus on solving on individual intertwiners in the 4D Euclidean theory. We review the standard way of solving the simplicity constraints using coherent intertwiners and we explain how these fit within the U(N) framework. Then we show how these constraints can be written as a closed u(N) algebra and we propose a set of U(N) coherent states that solves all the simplicity constraints weakly for an arbitrary Immirzi parameter.
Hamiltonian constraint in polymer parametrized field theory
International Nuclear Information System (INIS)
Laddha, Alok; Varadarajan, Madhavan
2011-01-01
Recently, a generally covariant reformulation of two-dimensional flat spacetime free scalar field theory known as parametrized field theory was quantized using loop quantum gravity (LQG) type ''polymer'' representations. Physical states were constructed, without intermediate regularization structures, by averaging over the group of gauge transformations generated by the constraints, the constraint algebra being a Lie algebra. We consider classically equivalent combinations of these constraints corresponding to a diffeomorphism and a Hamiltonian constraint, which, as in gravity, define a Dirac algebra. Our treatment of the quantum constraints parallels that of LQG and obtains the following results, expected to be of use in the construction of the quantum dynamics of LQG: (i) the (triangulated) Hamiltonian constraint acts only on vertices, its construction involves some of the same ambiguities as in LQG and its action on diffeomorphism invariant states admits a continuum limit, (ii) if the regulating holonomies are in representations tailored to the edge labels of the state, all previously obtained physical states lie in the kernel of the Hamiltonian constraint, (iii) the commutator of two (density weight 1) Hamiltonian constraints as well as the operator correspondent of their classical Poisson bracket converge to zero in the continuum limit defined by diffeomorphism invariant states, and vanish on the Lewandowski-Marolf habitat, (iv) the rescaled density 2 Hamiltonian constraints and their commutator are ill-defined on the Lewandowski-Marolf habitat despite the well-definedness of the operator correspondent of their classical Poisson bracket there, (v) there is a new habitat which supports a nontrivial representation of the Poisson-Lie algebra of density 2 constraints.
Natural Constraints to Species Diversification.
Directory of Open Access Journals (Sweden)
Eric Lewitus
2016-08-01
Full Text Available Identifying modes of species diversification is fundamental to our understanding of how biodiversity changes over evolutionary time. Diversification modes are captured in species phylogenies, but characterizing the landscape of diversification has been limited by the analytical tools available for directly comparing phylogenetic trees of groups of organisms. Here, we use a novel, non-parametric approach and 214 family-level phylogenies of vertebrates representing over 500 million years of evolution to identify major diversification modes, to characterize phylogenetic space, and to evaluate the bounds and central tendencies of species diversification. We identify five principal patterns of diversification to which all vertebrate families hold. These patterns, mapped onto multidimensional space, constitute a phylogenetic space with distinct properties. Firstly, phylogenetic space occupies only a portion of all possible tree space, showing family-level phylogenies to be constrained to a limited range of diversification patterns. Secondly, the geometry of phylogenetic space is delimited by quantifiable trade-offs in tree size and the heterogeneity and stem-to-tip distribution of branching events. These trade-offs are indicative of the instability of certain diversification patterns and effectively bound speciation rates (for successful clades within upper and lower limits. Finally, both the constrained range and geometry of phylogenetic space are established by the differential effects of macroevolutionary processes on patterns of diversification. Given these properties, we show that the average path through phylogenetic space over evolutionary time traverses several diversification stages, each of which is defined by a different principal pattern of diversification and directed by a different macroevolutionary process. The identification of universal patterns and natural constraints to diversification provides a foundation for understanding the
Natural Constraints to Species Diversification.
Lewitus, Eric; Morlon, Hélène
2016-08-01
Identifying modes of species diversification is fundamental to our understanding of how biodiversity changes over evolutionary time. Diversification modes are captured in species phylogenies, but characterizing the landscape of diversification has been limited by the analytical tools available for directly comparing phylogenetic trees of groups of organisms. Here, we use a novel, non-parametric approach and 214 family-level phylogenies of vertebrates representing over 500 million years of evolution to identify major diversification modes, to characterize phylogenetic space, and to evaluate the bounds and central tendencies of species diversification. We identify five principal patterns of diversification to which all vertebrate families hold. These patterns, mapped onto multidimensional space, constitute a phylogenetic space with distinct properties. Firstly, phylogenetic space occupies only a portion of all possible tree space, showing family-level phylogenies to be constrained to a limited range of diversification patterns. Secondly, the geometry of phylogenetic space is delimited by quantifiable trade-offs in tree size and the heterogeneity and stem-to-tip distribution of branching events. These trade-offs are indicative of the instability of certain diversification patterns and effectively bound speciation rates (for successful clades) within upper and lower limits. Finally, both the constrained range and geometry of phylogenetic space are established by the differential effects of macroevolutionary processes on patterns of diversification. Given these properties, we show that the average path through phylogenetic space over evolutionary time traverses several diversification stages, each of which is defined by a different principal pattern of diversification and directed by a different macroevolutionary process. The identification of universal patterns and natural constraints to diversification provides a foundation for understanding the deep-time evolution of
Natural Constraints to Species Diversification
Lewitus, Eric; Morlon, Hélène
2016-01-01
Identifying modes of species diversification is fundamental to our understanding of how biodiversity changes over evolutionary time. Diversification modes are captured in species phylogenies, but characterizing the landscape of diversification has been limited by the analytical tools available for directly comparing phylogenetic trees of groups of organisms. Here, we use a novel, non-parametric approach and 214 family-level phylogenies of vertebrates representing over 500 million years of evolution to identify major diversification modes, to characterize phylogenetic space, and to evaluate the bounds and central tendencies of species diversification. We identify five principal patterns of diversification to which all vertebrate families hold. These patterns, mapped onto multidimensional space, constitute a phylogenetic space with distinct properties. Firstly, phylogenetic space occupies only a portion of all possible tree space, showing family-level phylogenies to be constrained to a limited range of diversification patterns. Secondly, the geometry of phylogenetic space is delimited by quantifiable trade-offs in tree size and the heterogeneity and stem-to-tip distribution of branching events. These trade-offs are indicative of the instability of certain diversification patterns and effectively bound speciation rates (for successful clades) within upper and lower limits. Finally, both the constrained range and geometry of phylogenetic space are established by the differential effects of macroevolutionary processes on patterns of diversification. Given these properties, we show that the average path through phylogenetic space over evolutionary time traverses several diversification stages, each of which is defined by a different principal pattern of diversification and directed by a different macroevolutionary process. The identification of universal patterns and natural constraints to diversification provides a foundation for understanding the deep-time evolution of
Few-body hypernuclear constraints
International Nuclear Information System (INIS)
Gibson, B.F.
1993-01-01
Since the discovery of the first hyperfragment in a balloon flown emulsion stack some two score years ago, physicists have worked to understand how the addition of the strangeness degree of freedom alters the picture of nuclei and the baryon-baryon force. Because the Λ and Σ masses differ markedly from that of the proton and neutron, SU (3) symmetry is broken. How it is broken is a question of importance to the fundamental understanding of the baryon-baryon interaction. New dynamical symmetries, forbidden by the Pauli principle in conventional nuclei, appear. Three-body forces play a more significant role. A binding anomaly in A = 5 as well as a possible spin inversion between ground and excited states in A = 4 appear. Surprisingly narrow structure near the threshold for Σ production has been reported in the 4 He (K - , π - ) spectrum while no corresponding structure is observed in the companion 4 He(K - , π + ) spectrum; this has been interpreted as evidence for a Σ 4 He bound state. Finally, the reported observation of ΛΛ-hypernuclei, in particular ΛΛ 6 He, bears directly upon the possibilities for the prediction of a bound H particle--the S = -2 dibaryon. Although it is not feasible to invert the analysis and determine the interaction from the data on few-body systems, it is possible to utilize these data to constrain the models, provided one is careful. The author will explore briefly the constraints which the few-body data impose and the level of understanding that has been achieved
Constraint Handling Rules with Binders, Patterns and Generic Quantification
Serrano, Alejandro; Hage, J.
2017-01-01
Constraint Handling Rules provide descriptions for constraint solvers. However, they fall short when those constraints specify some binding structure, like higher-rank types in a constraint-based type inference algorithm. In this paper, the term syntax of constraints is replaced by λ-tree syntax, in
Liquidity Constraints and Fiscal Stabilization Policy
DEFF Research Database (Denmark)
Kristoffersen, Mark Strøm
It is often claimed that the presence of liquidity constrained households enhances the need for and the effects of fi…scal stabilization policies. This paper studies this in a model of a small open economy with liquidity constrained households. The results show that the consequences of liquidity...... constraints are more complex than previously thought: The optimal stabilization policy in case of productivity shocks is independent of the liquidity constraints, and the presence of liquidity constraints tends to reduce the need for an active policy stabilizing productivity shocks....
Use of dose constraints for occupational exposure
International Nuclear Information System (INIS)
Kaijage, Tunu
2015-02-01
The use of dose constraints for occupational exposure was reviewed in this project. The role of dose constraints as used in optimization of protection of workers was described. Different issues to be considered in application of the concept and challenges associated with their implementation were also discussed. The situation where dose constraints could be misinterpreted to dose limits is also explained as the two are clearly differentiated by the International Commission of Radiological Protection (ICRP) Publication 103. Moreover, recommendations to all parties responsible for protection and safety of workers were discussed. (au)
Constraint satisfaction problems CSP formalisms and techniques
Ghedira, Khaled
2013-01-01
A Constraint Satisfaction Problem (CSP) consists of a set of variables, a domain of values for each variable and a set of constraints. The objective is to assign a value for each variable such that all constraints are satisfied. CSPs continue to receive increased attention because of both their high complexity and their omnipresence in academic, industrial and even real-life problems. This is why they are the subject of intense research in both artificial intelligence and operations research. This book introduces the classic CSP and details several extensions/improvements of both formalisms a
Expressing Model Constraints Visually with VMQL
DEFF Research Database (Denmark)
Störrle, Harald
2011-01-01
) for specifying constraints on UML models. We examine VMQL's usability by controlled experiments and its expressiveness by a representative sample. We conclude that VMQL is less expressive than OCL, although expressive enough for most of the constraints in the sample. In terms of usability, however, VMQL......OCL is the de facto standard language for expressing constraints and queries on UML models. However, OCL expressions are very difficult to create, understand, and maintain, even with the sophisticated tool support now available. In this paper, we propose to use the Visual Model Query Language (VMQL...
Dose constraints, what are they now?
International Nuclear Information System (INIS)
Lazo, T.
2005-01-01
The concept of a source-related dose constraint was first introduced in ICPR publication 60. The idea was to provide a number that individual exposures from a single, specific source should not exceed, and below which optimisation of protection should take place. Dose constraints were applied to occupational and public exposures from practices. In order to simplify and clarify the ICRP's recommendations, the latest draft, RPO5, presents dose constraints again, and with the same meaning as in publication 60. However, the dose constraints are now applied in all situations, not just practices. This new approach does provide simplification, in that a single concept is applied to all types of exposures (normal situations, accident situations, and existing situations). However, the approach and numerical values that are selected by regulatory authorities for the application of the concept, particularly in normal situations which are also subject to dose limits, will be crucial to the implementation of the system of radiological protection. (author)
Biological constraints do not entail cognitive closure.
Vlerick, Michael
2014-12-01
From the premise that our biology imposes cognitive constraints on our epistemic activities, a series of prominent authors--most notably Fodor, Chomsky and McGinn--have argued that we are cognitively closed to certain aspects and properties of the world. Cognitive constraints, they argue, entail cognitive closure. I argue that this is not the case. More precisely, I detect two unwarranted conflations at the core of arguments deriving closure from constraints. The first is a conflation of what I will refer to as 'representation' and 'object of representation'. The second confuses the cognitive scope of the assisted mind for that of the unassisted mind. Cognitive closure, I conclude, cannot be established from pointing out the (uncontroversial) existence of cognitive constraints. Copyright © 2014 Elsevier Ltd. All rights reserved.
institutional and resource constraints that inhibit contractor ...
African Journals Online (AJOL)
p2333147
Keywords: Institutions; small-scale contractor performance; sugar industry. ABSTRACT ..... diverse cultural settings, women, specifically widowed or single women, have a .... constraints on business growth, such as the work limitations placed.
Constraint theory multidimensional mathematical model management
Friedman, George J
2017-01-01
Packed with new material and research, this second edition of George Friedman’s bestselling Constraint Theory remains an invaluable reference for all engineers, mathematicians, and managers concerned with modeling. As in the first edition, this text analyzes the way Constraint Theory employs bipartite graphs and presents the process of locating the “kernel of constraint” trillions of times faster than brute-force approaches, determining model consistency and computational allowability. Unique in its abundance of topological pictures of the material, this book balances left- and right-brain perceptions to provide a thorough explanation of multidimensional mathematical models. Much of the extended material in this new edition also comes from Phan Phan’s PhD dissertation in 2011, titled “Expanding Constraint Theory to Determine Well-Posedness of Large Mathematical Models.” Praise for the first edition: "Dr. George Friedman is indisputably the father of the very powerful methods of constraint theory...
Route constraints model based on polychromatic sets
Yin, Xianjun; Cai, Chao; Wang, Houjun; Li, Dongwu
2018-03-01
With the development of unmanned aerial vehicle (UAV) technology, the fields of its application are constantly expanding. The mission planning of UAV is especially important, and the planning result directly influences whether the UAV can accomplish the task. In order to make the results of mission planning for unmanned aerial vehicle more realistic, it is necessary to consider not only the physical properties of the aircraft, but also the constraints among the various equipment on the UAV. However, constraints among the equipment of UAV are complex, and the equipment has strong diversity and variability, which makes these constraints difficult to be described. In order to solve the above problem, this paper, referring to the polychromatic sets theory used in the advanced manufacturing field to describe complex systems, presents a mission constraint model of UAV based on polychromatic sets.
Constraint-based Attribute and Interval Planning
Jonsson, Ari; Frank, Jeremy
2013-01-01
In this paper we describe Constraint-based Attribute and Interval Planning (CAIP), a paradigm for representing and reasoning about plans. The paradigm enables the description of planning domains with time, resources, concurrent activities, mutual exclusions among sets of activities, disjunctive preconditions and conditional effects. We provide a theoretical foundation for the paradigm, based on temporal intervals and attributes. We then show how the plans are naturally expressed by networks of constraints, and show that the process of planning maps directly to dynamic constraint reasoning. In addition, we de ne compatibilities, a compact mechanism for describing planning domains. We describe how this framework can incorporate the use of constraint reasoning technology to improve planning. Finally, we describe EUROPA, an implementation of the CAIP framework.
Automated constraint placement to maintain pile shape
Hsu, Shu-Wei; Keyser, John
2012-01-01
structure. Next, for stabilizing the structure, we pick suitable objects from those passing the equilibrium analysis and then restrict their DOFs by managing the insertion of constraints on them. The method is suitable for controlling stacking behavior
Cosmological constraints on Brans-Dicke theory.
Avilez, A; Skordis, C
2014-07-04
We report strong cosmological constraints on the Brans-Dicke (BD) theory of gravity using cosmic microwave background data from Planck. We consider two types of models. First, the initial condition of the scalar field is fixed to give the same effective gravitational strength Geff today as the one measured on Earth, GN. In this case, the BD parameter ω is constrained to ω>692 at the 99% confidence level, an order of magnitude improvement over previous constraints. In the second type, the initial condition for the scalar is a free parameter leading to a somewhat stronger constraint of ω>890, while Geff is constrained to 0.981theory and are valid for any Horndeski theory, the most general second-order scalar-tensor theory, which approximates the BD theory on cosmological scales. In this sense, our constraints place strong limits on possible modifications of gravity that might explain cosmic acceleration.
CONSTRAINTS TO USE OF MOBILE TELEPHONY FOR ...
African Journals Online (AJOL)
Key words: Constraints, mobile telephony, frequency, farmers and telecommunications service ... efficient sharing of agricultural information ... calls on the mobile phone without the need .... adequate training on the use of mobile .... Job Market.
Modernizing China's Military: Opportunities and Constraints
National Research Council Canada - National Science Library
Crane, Keith; Cliff, Roger; Medeiros, Evan; Mulvenon, James; Overholt, William
2005-01-01
The purpose of this study is to assess future resource constraints on, and potential domestic economic and industrial contributions to, the ability of the Chinese military to become a significant threat to U.S. forces by 2025...
Optimal capital stock and financing constraints
Saltari, Enrico; Giuseppe, Travaglini
2011-01-01
In this paper we show that financing constraints affect the optimal level of capital stock even when the financing constraint is ineffective. This happens when the firm rationally anticipates that access to external financing resources may be rationed in the future. We will show that with these expectations, the optimal investment policy is to invest less in any given period, thereby lowering the desired optimal capital stock in the long run.
Credit Constraints, Political Instability, and Capital Accumulation
Risto Herrala; Rima Turk-Ariss
2013-01-01
We investigate the complex interactions between credit constraints, political instability, and capital accumulation using a novel approach based on Kiyotaki and Moore’s (1997) theoretical framework. Drawing on a unique firm-level data set from Middle-East and North Africa (MENA), empirical findings point to a large and significant effect of credit conditions on capital accumulation and suggest that continued political unrest worsens credit constraints. The results support the view that financ...
Cyclic labellings with constraints at two distances
Leese, R; Noble, S D
2004-01-01
Motivated by problems in radio channel assignment, we consider the vertex-labelling of graphs with non-negative integers. The objective is to minimise the span of the labelling, subject to constraints imposed at graph distances one and two. We show that the minimum span is (up to rounding) a piecewise linear function of the constraints, and give a complete specification, together with associated optimal assignments, for trees and cycles.
Portfolios with nonlinear constraints and spin glasses
Gábor, Adrienn; Kondor, I.
1999-12-01
In a recent paper Galluccio, Bouchaud and Potters demonstrated that a certain portfolio problem with a nonlinear constraint maps exactly onto finding the ground states of a long-range spin glass, with the concomitant nonuniqueness and instability of the optimal portfolios. Here we put forward geometric arguments that lead to qualitatively similar conclusions, without recourse to the methods of spin glass theory, and give two more examples of portfolio problems with convex nonlinear constraints.
Future Cosmological Constraints From Fast Radio Bursts
Walters, Anthony; Weltman, Amanda; Gaensler, B. M.; Ma, Yin-Zhe; Witzemann, Amadeus
2018-03-01
We consider the possible observation of fast radio bursts (FRBs) with planned future radio telescopes, and investigate how well the dispersions and redshifts of these signals might constrain cosmological parameters. We construct mock catalogs of FRB dispersion measure (DM) data and employ Markov Chain Monte Carlo analysis, with which we forecast and compare with existing constraints in the flat ΛCDM model, as well as some popular extensions that include dark energy equation of state and curvature parameters. We find that the scatter in DM observations caused by inhomogeneities in the intergalactic medium (IGM) poses a big challenge to the utility of FRBs as a cosmic probe. Only in the most optimistic case, with a high number of events and low IGM variance, do FRBs aid in improving current constraints. In particular, when FRBs are combined with CMB+BAO+SNe+H 0 data, we find the biggest improvement comes in the {{{Ω }}}{{b}}{h}2 constraint. Also, we find that the dark energy equation of state is poorly constrained, while the constraint on the curvature parameter, Ω k , shows some improvement when combined with current constraints. When FRBs are combined with future baryon acoustic oscillation (BAO) data from 21 cm Intensity Mapping, we find little improvement over the constraints from BAOs alone. However, the inclusion of FRBs introduces an additional parameter constraint, {{{Ω }}}{{b}}{h}2, which turns out to be comparable to existing constraints. This suggests that FRBs provide valuable information about the cosmological baryon density in the intermediate redshift universe, independent of high-redshift CMB data.
Generalized Pauli constraints in small atoms
Schilling, Christian; Altunbulak, Murat; Knecht, Stefan; Lopes, Alexandre; Whitfield, James D.; Christandl, Matthias; Gross, David; Reiher, Markus
2018-05-01
The natural occupation numbers of fermionic systems are subject to nontrivial constraints, which include and extend the original Pauli principle. A recent mathematical breakthrough has clarified their mathematical structure and has opened up the possibility of a systematic analysis. Early investigations have found evidence that these constraints are exactly saturated in several physically relevant systems, e.g., in a certain electronic state of the beryllium atom. It has been suggested that, in such cases, the constraints, rather than the details of the Hamiltonian, dictate the system's qualitative behavior. Here, we revisit this question with state-of-the-art numerical methods for small atoms. We find that the constraints are, in fact, not exactly saturated, but that they lie much closer to the surface defined by the constraints than the geometry of the problem would suggest. While the results seem incompatible with the statement that the generalized Pauli constraints drive the behavior of these systems, they suggest that the qualitatively correct wave-function expansions can in some systems already be obtained on the basis of a limited number of Slater determinants, which is in line with numerical evidence from quantum chemistry.
University Course Timetabling using Constraint Programming
Directory of Open Access Journals (Sweden)
Hadi Shahmoradi
2017-03-01
Full Text Available University course timetabling problem is a challenging and time-consuming task on the overall structure of timetable in every academic environment. The problem deals with many factors such as the number of lessons, classes, teachers, students and working time, and these are influenced by some hard and soft constraints. The aim of solving this problem is to assign courses and classes to teachers and students, so that the restrictions are held. In this paper, a constraint programming method is proposed to satisfy maximum constraints and expectation, in order to address university timetabling problem. For minimizing the penalty of soft constraints, a cost function is introduced and AHP method is used for calculating its coefficients. The proposed model is tested on department of management, University of Isfahan dataset using OPL on the IBM ILOG CPLEX Optimization Studio platform. A statistical analysis has been conducted and shows the performance of the proposed approach in satisfying all hard constraints and also the satisfying degree of the soft constraints is on maximum desirable level. The running time of the model is less than 20 minutes that is significantly better than the non-automated ones.
Reduction Of Constraints For Coupled Operations
International Nuclear Information System (INIS)
Raszewski, F.; Edwards, T.
2009-01-01
The homogeneity constraint was implemented in the Defense Waste Processing Facility (DWPF) Product Composition Control System (PCCS) to help ensure that the current durability models would be applicable to the glass compositions being processed during DWPF operations. While the homogeneity constraint is typically an issue at lower waste loadings (WLs), it may impact the operating windows for DWPF operations, where the glass forming systems may be limited to lower waste loadings based on fissile or heat load limits. In the sludge batch 1b (SB1b) variability study, application of the homogeneity constraint at the measurement acceptability region (MAR) limit eliminated much of the potential operating window for DWPF. As a result, Edwards and Brown developed criteria that allowed DWPF to relax the homogeneity constraint from the MAR to the property acceptance region (PAR) criterion, which opened up the operating window for DWPF operations. These criteria are defined as: (1) use the alumina constraint as currently implemented in PCCS (Al 2 O 3 (ge) 3 wt%) and add a sum of alkali constraint with an upper limit of 19.3 wt% (ΣM 2 O 2 O 3 constraint to 4 wt% (Al 2 O 3 (ge) 4 wt%). Herman et al. previously demonstrated that these criteria could be used to replace the homogeneity constraint for future sludge-only batches. The compositional region encompassing coupled operations flowsheets could not be bounded as these flowsheets were unknown at the time. With the initiation of coupled operations at DWPF in 2008, the need to revisit the homogeneity constraint was realized. This constraint was specifically addressed through the variability study for SB5 where it was shown that the homogeneity constraint could be ignored if the alumina and alkali constraints were imposed. Additional benefit could be gained if the homogeneity constraint could be replaced by the Al 2 O 3 and sum of alkali constraint for future coupled operations processing based on projections from Revision 14 of
Constraint-Muse: A Soft-Constraint Based System for Music Therapy
Hölzl, Matthias; Denker, Grit; Meier, Max; Wirsing, Martin
Monoidal soft constraints are a versatile formalism for specifying and solving multi-criteria optimization problems with dynamically changing user preferences. We have developed a prototype tool for interactive music creation, called Constraint Muse, that uses monoidal soft constraints to ensure that a dynamically generated melody harmonizes with input from other sources. Constraint Muse provides an easy to use interface based on Nintendo Wii controllers and is intended to be used in music therapy for people with Parkinson’s disease and for children with high-functioning autism or Asperger’s syndrome.
Energy Technology Data Exchange (ETDEWEB)
Latour, E
2007-10-15
This thesis applies the Gronau-London-Wyler (GLW) method to the B{sup {+-}} {yields} D{sup *}K{sup {+-}} decays in view of measuring the angle {gamma} of the unitarity triangle of the CKM matrix at the Babar experiment. After a review of CP violation, we describe the different paths used so far for measuring {gamma}, with a special emphasis on the GLW method. Then the analysis is presented. It relies on an optimized selection for maximizing signal sensitivity, and on an extended maximum likelihood fit from which we extract the four GLW observables A{sup *}(CP+), R{sup *}(CP+), A{sup *}(CP-) and R{sup *}(CP-). Results obtained using Run 1 to 5 of Babar, corresponding to 347 fb{sup -1}, i.e. 381*10{sup 6} BB-bar pairs, give A{sup *}(CP+) equals -0.114{+-}0.089{+-}0.007; R{sup *}(CP+) equals 1.313{+-}0.132{+-}0.029; A{sup *}(CP-) equals 0.060{+-}0.099{+-}0.016 and R{sup *}(CP-) equals 1.081{+-}0.119{+-}0.034. Translated into cartesian coordinates x{sub {+-}}{sup *} for comparing with Dalitz analysis, we get x{sub +}{sup *} equals 0,112{+-}0,061{+-}0,012; x{sub -}{sup *} equals 0,004{+-}0,059{+-}0,012. All these results are in agreement with previous measurements from Babar and Belle experiments. Precision is improved by a factor two on CP even observables and a factor three for CP odd observables, in particular due to the use of D{sup *} {yields} D{sup 0}{gamma} decays, and is better on x{sub {+-}}{sup *} than the world average of Babar and Belle Dalitz measurements. The statistics used is too small for providing a precise enough r{sub B}{sup *} with R{sup *}(CP{+-}) that could constrain {gamma}. However the combination of our results with Dalitz measurements will improve this constraint. (author)
Fuzzy Constraint-Based Agent Negotiation
Institute of Scientific and Technical Information of China (English)
Menq-Wen Lin; K. Robert Lai; Ting-Jung Yu
2005-01-01
Conflicts between two or more parties arise for various reasons and perspectives. Thus, resolution of conflicts frequently relies on some form of negotiation. This paper presents a general problem-solving framework for modeling multi-issue multilateral negotiation using fuzzy constraints. Agent negotiation is formulated as a distributed fuzzy constraint satisfaction problem (DFCSP). Fuzzy constrains are thus used to naturally represent each agent's desires involving imprecision and human conceptualization, particularly when lexical imprecision and subjective matters are concerned. On the other hand, based on fuzzy constraint-based problem-solving, our approach enables an agent not only to systematically relax fuzzy constraints to generate a proposal, but also to employ fuzzy similarity to select the alternative that is subject to its acceptability by the opponents. This task of problem-solving is to reach an agreement that benefits all agents with a high satisfaction degree of fuzzy constraints, and move towards the deal more quickly since their search focuses only on the feasible solution space. An application to multilateral negotiation of a travel planning is provided to demonstrate the usefulness and effectiveness of our framework.
Pair Production Constraints on Superluminal Neutrinos Revisited
International Nuclear Information System (INIS)
Brodsky, Stanley
2012-01-01
We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p 2 can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.
Diffusion Processes Satisfying a Conservation Law Constraint
Directory of Open Access Journals (Sweden)
J. Bakosi
2014-01-01
Full Text Available We investigate coupled stochastic differential equations governing N nonnegative continuous random variables that satisfy a conservation principle. In various fields a conservation law requires a set of fluctuating variables to be nonnegative and (if appropriately normalized sum to one. As a result, any stochastic differential equation model to be realizable must not produce events outside of the allowed sample space. We develop a set of constraints on the drift and diffusion terms of such stochastic models to ensure that both the nonnegativity and the unit-sum conservation law constraints are satisfied as the variables evolve in time. We investigate the consequences of the developed constraints on the Fokker-Planck equation, the associated system of stochastic differential equations, and the evolution equations of the first four moments of the probability density function. We show that random variables, satisfying a conservation law constraint, represented by stochastic diffusion processes, must have diffusion terms that are coupled and nonlinear. The set of constraints developed enables the development of statistical representations of fluctuating variables satisfying a conservation law. We exemplify the results with the bivariate beta process and the multivariate Wright-Fisher, Dirichlet, and Lochner’s generalized Dirichlet processes.
Faddeev-Jackiw quantization and constraints
International Nuclear Information System (INIS)
Barcelos-Neto, J.; Wotzasek, C.
1992-01-01
In a recent Letter, Faddeev and Jackiw have shown that the reduction of constrained systems into its canonical, first-order form, can bring some new insight into the research of this field. For sympletic manifolds the geometrical structure, called Dirac or generalized bracket, is obtained directly from the inverse of the nonsingular sympletic two-form matrix. In the cases of nonsympletic manifolds, this two-form is degenerated and cannot be inverted to provide the generalized brackets. This singular behavior of the sympletic matrix is indicative of the presence of constraints that have to be carefully considered to yield to consistent results. One has two possible routes to treat this problem: Dirac has taught us how to implement the constraints into the potential part (Hamiltonian) of the canonical Lagrangian, leading to the well-known Dirac brackets, which are consistent with the constraints and can be mapped into quantum commutators (modulo ordering terms). The second route, suggested by Faddeev and Jackiw, and followed in this paper, is to implement the constraints directly into the canonical part of the first order Lagrangian, using the fact that the consistence condition for the stability of the constrained manifold is linear in the time derivative. This algorithm may lead to an invertible two-form sympletic matrix from where the Dirac brackets are readily obtained. This algorithm is used in this paper to investigate some aspects of the quantization of constrained systems with first- and second-class constraints in the sympletic approach
Latin hypercube sampling with inequality constraints
International Nuclear Information System (INIS)
Iooss, B.; Petelet, M.; Asserin, O.; Loredo, A.
2010-01-01
In some studies requiring predictive and CPU-time consuming numerical models, the sampling design of the model input variables has to be chosen with caution. For this purpose, Latin hypercube sampling has a long history and has shown its robustness capabilities. In this paper we propose and discuss a new algorithm to build a Latin hypercube sample (LHS) taking into account inequality constraints between the sampled variables. This technique, called constrained Latin hypercube sampling (cLHS), consists in doing permutations on an initial LHS to honor the desired monotonic constraints. The relevance of this approach is shown on a real example concerning the numerical welding simulation, where the inequality constraints are caused by the physical decreasing of some material properties in function of the temperature. (authors)
Lorentz violation. Motivation and new constraints
International Nuclear Information System (INIS)
Liberati, S.; Maccione, L.
2009-09-01
We review the main theoretical motivations and observational constraints on Planck scale sup-pressed violations of Lorentz invariance. After introducing the problems related to the phenomenological study of quantum gravitational effects, we discuss the main theoretical frameworks within which possible departures from Lorentz invariance can be described. In particular, we focus on the framework of Effective Field Theory, describing several possible ways of including Lorentz violation therein and discussing their theoretical viability. We review the main low energy effects that are expected in this framework. We discuss the current observational constraints on such a framework, focusing on those achievable through high-energy astrophysics observations. In this context we present a summary of the most recent and strongest constraints on QED with Lorentz violating non-renormalizable operators. Finally, we discuss the present status of the field and its future perspectives. (orig.)
WMAP constraints on the Cardassian model
International Nuclear Information System (INIS)
Sen, A.A.; Sen, S.
2003-01-01
We investigate the constraints on the Cardassian model using the recent results from the Wilkinson microwave anisotropy probe for the locations of the peaks of the cosmic microwave background (CMB) anisotropy spectrum. We find that the model is consistent with the recent observational data for a certain range of the model parameter n and the cosmological parameters. We find that the Cardassian model is favored compared to the ΛCDM model for a higher spectral index (n s ≅1) together with a lower value of the Hubble parameter h (h≤0.71). But for smaller values of n s , both ΛCDM and Cardassian models are equally favored. Also, irrespective of supernova constraints, CMB data alone predict the current acceleration of the Universe in this model. We have also studied the constraint on σ 8 , the rms density fluctuations at the 8h -1 Mpc scale
Some general constraints on identical band symmetries
International Nuclear Information System (INIS)
Guidry, M.W.; Strayer, M.R.; Wu, C.; Feng, D.H.
1993-01-01
We argue on general grounds that nearly identical bands observed for superdeformation and less frequently for normal deformation must be explicable in terms of a symmetry having a microscopic basis. We assume that the unknown symmetry is associated with a Lie algebra generated by terms bilinear in fermion creation and annihilation operators. Observed features of these bands and the general properties of Lie groups are then used to place constraints on acceptable algebras. Additional constraints are placed by assuming that the collective spectrum is associated with a dynamical symmetry, and examining the subgroup structure required by phenomenology. We observe that requisite symmetry cannot be unitary, and that the simplest known group structures consistent with these minimal criteria are associated with the Ginocchio algebras employed in the fermion dynamical symmetry model. However, our arguments are general in nature, and we propose that they imply model-independent constraints on any candidate explanation for identical bands
Lorentz violation. Motivation and new constraints
Energy Technology Data Exchange (ETDEWEB)
Liberati, S. [Scuola Internazionale Superiore di Studi Avanzati SISSA, Trieste (Italy); Istituto Nazionale di Fisica Nucleare INFN, Sezione di Trieste (Italy); Maccione, L. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2009-09-15
We review the main theoretical motivations and observational constraints on Planck scale sup-pressed violations of Lorentz invariance. After introducing the problems related to the phenomenological study of quantum gravitational effects, we discuss the main theoretical frameworks within which possible departures from Lorentz invariance can be described. In particular, we focus on the framework of Effective Field Theory, describing several possible ways of including Lorentz violation therein and discussing their theoretical viability. We review the main low energy effects that are expected in this framework. We discuss the current observational constraints on such a framework, focusing on those achievable through high-energy astrophysics observations. In this context we present a summary of the most recent and strongest constraints on QED with Lorentz violating non-renormalizable operators. Finally, we discuss the present status of the field and its future perspectives. (orig.)
Constraints and spandrels of interareal connectomes
Rubinov, Mikail
2016-12-01
Interareal connectomes are whole-brain wiring diagrams of white-matter pathways. Recent studies have identified modules, hubs, module hierarchies and rich clubs as structural hallmarks of these wiring diagrams. An influential current theory postulates that connectome modules are adequately explained by evolutionary pressures for wiring economy, but that the other hallmarks are not explained by such pressures and are therefore less trivial. Here, we use constraint network models to test these postulates in current gold-standard vertebrate and invertebrate interareal-connectome reconstructions. We show that empirical wiring-cost constraints inadequately explain connectome module organization, and that simultaneous module and hub constraints induce the structural byproducts of hierarchies and rich clubs. These byproducts, known as spandrels in evolutionary biology, include the structural substrate of the default-mode network. Our results imply that currently standard connectome characterizations are based on circular analyses or double dipping, and we emphasize an integrative approach to future connectome analyses for avoiding such pitfalls.
Ring power balance observing plasma stability constraints
International Nuclear Information System (INIS)
Campbell, R.B.; Logan, B.G.
1982-01-01
Ring power balance is performed for an E-ring stabilized tandem mirror reactor, taking into account constraints imposed by plasma stability. The two most important criteria are the stability of the core interchange and hot electron interchange modes. The former determines the ring thickness, the latter determines the minimum hot electron temperature; both quantities are important for power balance. The combination of the hot electron interchange constraint and the fact that the barrier density is low places the operating point on the synchrotron dominated branch of power balance. The reference case considered here requires a reasonable 34 MW of heating power deposited in the rings. We also have examined the sensitivity of the required ring power on uncertainties in the numerical coefficients of the stability constraints. We have found that the heating power is strongly affected
Effective constraint algebras with structure functions
International Nuclear Information System (INIS)
Bojowald, Martin; Brahma, Suddhasattwa
2016-01-01
This article presents the result that fluctuations and higher moments of a state, by themselves, do not imply quantum corrections in structure functions of constrained systems. Moment corrections are isolated from other types of quantum effects, such as factor-ordering choices and regularization, by introducing a new condition with two parts: (i) having a direct (or faithful) quantization of the classical structure functions, (ii) free of factor-ordering ambiguities. In particular, it is assumed that the classical constraints can be quantized in an anomaly free way, so that properties of the resulting constraint algebras can be derived. If the two-part condition is not satisfied, effective constraints can still be evaluated, but quantum effects may be stronger. Consequences for canonical quantum gravity, whose structure functions encode space–time structure, are discussed. In particular, deformed algebras found in models of loop quantum gravity provide reliable information even in the Planck regime. (paper)
Managing Constraint Generators in Retail Design Processes
DEFF Research Database (Denmark)
Münster, Mia Borch; Haug, Anders
case studies of fashion store design projects, the present paper addresses this gap. The and six case studies of fashion store design projects, the present paper sheds light on the types of constraints generated by the relevant constraint generators. The paper shows that in the cases studied......Retail design concepts are complex designs meeting functional and aesthetic demands. During a design process a retail designer has to consider various constraint generators such as stakeholder interests, physical limitations and restrictions. Obviously the architectural site, legislators...... and landlords need to be considered as well as the interest of the client and brand owner. Furthermore the users need to be taken into account in order to develop an interesting and functional shopping and working environments. Finally, suppliers and competitors may influence the design with regard...
Coverage-based constraints for IMRT optimization
Mescher, H.; Ulrich, S.; Bangert, M.
2017-09-01
Radiation therapy treatment planning requires an incorporation of uncertainties in order to guarantee an adequate irradiation of the tumor volumes. In current clinical practice, uncertainties are accounted for implicitly with an expansion of the target volume according to generic margin recipes. Alternatively, it is possible to account for uncertainties by explicit minimization of objectives that describe worst-case treatment scenarios, the expectation value of the treatment or the coverage probability of the target volumes during treatment planning. In this note we show that approaches relying on objectives to induce a specific coverage of the clinical target volumes are inevitably sensitive to variation of the relative weighting of the objectives. To address this issue, we introduce coverage-based constraints for intensity-modulated radiation therapy (IMRT) treatment planning. Our implementation follows the concept of coverage-optimized planning that considers explicit error scenarios to calculate and optimize patient-specific probabilities q(\\hat{d}, \\hat{v}) of covering a specific target volume fraction \\hat{v} with a certain dose \\hat{d} . Using a constraint-based reformulation of coverage-based objectives we eliminate the trade-off between coverage and competing objectives during treatment planning. In-depth convergence tests including 324 treatment plan optimizations demonstrate the reliability of coverage-based constraints for varying levels of probability, dose and volume. General clinical applicability of coverage-based constraints is demonstrated for two cases. A sensitivity analysis regarding penalty variations within this planing study based on IMRT treatment planning using (1) coverage-based constraints, (2) coverage-based objectives, (3) probabilistic optimization, (4) robust optimization and (5) conventional margins illustrates the potential benefit of coverage-based constraints that do not require tedious adjustment of target volume objectives.
Judgement of Design Scheme Based on Flexible Constraint in ICAD
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The conception of flexible constraint is proposed in the paper. The solution of flexible constraint is in special range, and maybe different in different instances of same design scheme. The paper emphasis on how to evaluate and optimize a design scheme with flexible constraints based on the satisfaction degree function defined on flexible constraints. The conception of flexible constraint is used to solve constraint conflict and design optimization in complicated constraint-based assembly design by the PFM parametrization assembly design system. An instance of gear-box design is used for verifying optimization method.
q-Virasoro constraints in matrix models
Energy Technology Data Exchange (ETDEWEB)
Nedelin, Anton [Dipartimento di Fisica, Università di Milano-Bicocca and INFN, sezione di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano (Italy); Department of Physics and Astronomy, Uppsala university,Box 516, SE-75120 Uppsala (Sweden); Zabzine, Maxim [Department of Physics and Astronomy, Uppsala university,Box 516, SE-75120 Uppsala (Sweden)
2017-03-20
The Virasoro constraints play the important role in the study of matrix models and in understanding of the relation between matrix models and CFTs. Recently the localization calculations in supersymmetric gauge theories produced new families of matrix models and we have very limited knowledge about these matrix models. We concentrate on elliptic generalization of hermitian matrix model which corresponds to calculation of partition function on S{sup 3}×S{sup 1} for vector multiplet. We derive the q-Virasoro constraints for this matrix model. We also observe some interesting algebraic properties of the q-Virasoro algebra.
Constraints on reusability of learning objects
DEFF Research Database (Denmark)
May, Michael; Hussmann, Peter Munkebo; Jensen, Anne Skov
2010-01-01
It is the aim of this paper to discuss some didactic constraints on the use and reuse of digital modular learning objects. Engineering education is used as the specific context of use with examples from courses in introductory electronics and mathematics. Digital multimedia and modular learning....... Constraints on reuse arise from the nature of conceptual understanding in higher education and the functionality of learning objects within present technologies. We will need didactic as well as technical perspectives on learning objects in designing for understanding....
Constraints on hadronically decaying dark matter
Energy Technology Data Exchange (ETDEWEB)
Garny, Mathias [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ibarra, Alejandro [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Tran, David [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Minnesota Univ., Minneapolis, MN (United States). School of Physics and Astronomy
2012-05-15
We present general constraints on dark matter stability in hadronic decay channels derived from measurements of cosmic-ray antiprotons.We analyze various hadronic decay modes in a model-independent manner by examining the lowest-order decays allowed by gauge and Lorentz invariance for scalar and fermionic dark matter particles and present the corresponding lower bounds on the partial decay lifetimes in those channels. We also investigate the complementarity between hadronic and gamma-ray constraints derived from searches for monochromatic lines in the sky, which can be produced at the quantum level if the dark matter decays into quark-antiquark pairs at leading order.
Constraints on hadronically decaying dark matter
International Nuclear Information System (INIS)
Garny, Mathias; Ibarra, Alejandro; Tran, David; Minnesota Univ., Minneapolis, MN
2012-05-01
We present general constraints on dark matter stability in hadronic decay channels derived from measurements of cosmic-ray antiprotons.We analyze various hadronic decay modes in a model-independent manner by examining the lowest-order decays allowed by gauge and Lorentz invariance for scalar and fermionic dark matter particles and present the corresponding lower bounds on the partial decay lifetimes in those channels. We also investigate the complementarity between hadronic and gamma-ray constraints derived from searches for monochromatic lines in the sky, which can be produced at the quantum level if the dark matter decays into quark-antiquark pairs at leading order.
Orthology and paralogy constraints: satisfiability and consistency
Lafond, Manuel; El-Mabrouk, Nadia
2014-01-01
Background A variety of methods based on sequence similarity, reconciliation, synteny or functional characteristics, can be used to infer orthology and paralogy relations between genes of a given gene family G . But is a given set C of orthology/paralogy constraints possible, i.e., can they simultaneously co-exist in an evolutionary history for G ? While previous studies have focused on full sets of constraints, here we consider the general case where C does not necessarily involve a ...
Reduction of Constraints: Applicability of the Homogeneity Constraint for Macrobatch 3
International Nuclear Information System (INIS)
Peeler, D.K.
2001-01-01
The Product Composition Control System (PCCS) is used to determine the acceptability of each batch of Defense Waste Processing Facility (DWPF) melter feed in the Slurry Mix Evaporator (SME). This control system imposes several constraints on the composition of the contents of the SME to define acceptability. These constraints relate process or product properties to composition via prediction models. A SME batch is deemed acceptable if its sample composition measurements lead to acceptable property predictions after accounting for modeling, measurement and analytic uncertainties. The baseline document guiding the use of these data and models is ''SME Acceptability Determination for DWPF Process Control (U)'' by Brown and Postles [1996]. A minimum of three PCCS constraints support the prediction of the glass durability from a given SME batch. The Savannah River Technology Center (SRTC) is reviewing all of the PCCS constraints associated with durability. The purpose of this review is to revisit these constraints in light of the additional knowledge gained since the beginning of radioactive operations at DWPF and to identify any supplemental studies needed to amplify this knowledge so that redundant or overly conservative constraints can be eliminated or replaced by more appropriate constraints
Loosening Psychometric Constraints on Educational Assessments
Kane, Michael T.
2017-01-01
In response to an argument by Baird, Andrich, Hopfenbeck and Stobart (2017), Michael Kane states that there needs to be a better fit between educational assessment and learning theory. In line with this goal, Kane will examine how psychometric constraints might be loosened by relaxing some psychometric "rules" in some assessment…
Fish farmers' perceptions of constraints affecting aquaculture ...
African Journals Online (AJOL)
The study focused on fish farmers' perceptions of constraints affecting aquaculture development in Akwa-Ibom State of Nigeria. Random sampling procedure was used to select 120 respondents from whom primary data was collected. Data analysis was with the aid of descriptive statistics. Results show that fish farming ...
Confluence Modulo Equivalence in Constraint Handling Rules
DEFF Research Database (Denmark)
Christiansen, Henning; Kirkeby, Maja Hanne
2015-01-01
Previous results on confluence for Constraint Handling Rules, CHR, are generalized to take into account user-defined state equivalence relations. This allows a much larger class of programs to enjoy the advantages of confluence, which include various optimization techniques and simplified...
Domain general constraints on statistical learning.
Thiessen, Erik D
2011-01-01
All theories of language development suggest that learning is constrained. However, theories differ on whether these constraints arise from language-specific processes or have domain-general origins such as the characteristics of human perception and information processing. The current experiments explored constraints on statistical learning of patterns, such as the phonotactic patterns of an infants' native language. Infants in these experiments were presented with a visual analog of a phonotactic learning task used by J. R. Saffran and E. D. Thiessen (2003). Saffran and Thiessen found that infants' phonotactic learning was constrained such that some patterns were learned more easily than other patterns. The current results indicate that infants' learning of visual patterns shows the same constraints as infants' learning of phonotactic patterns. This is consistent with theories suggesting that constraints arise from domain-general sources and, as such, should operate over many kinds of stimuli in addition to linguistic stimuli. © 2011 The Author. Child Development © 2011 Society for Research in Child Development, Inc.
Constraint-Referenced Analytics of Algebra Learning
Sutherland, Scot M.; White, Tobin F.
2016-01-01
The development of the constraint-referenced analytics tool for monitoring algebra learning activities presented here came from the desire to firstly, take a more quantitative look at student responses in collaborative algebra activities, and secondly, to situate those activities in a more traditional introductory algebra setting focusing on…
Robust Utility Maximization Under Convex Portfolio Constraints
International Nuclear Information System (INIS)
Matoussi, Anis; Mezghani, Hanen; Mnif, Mohamed
2015-01-01
We study a robust maximization problem from terminal wealth and consumption under a convex constraints on the portfolio. We state the existence and the uniqueness of the consumption–investment strategy by studying the associated quadratic backward stochastic differential equation. We characterize the optimal control by using the duality method and deriving a dynamic maximum principle
Prospects and Constraints of Household Irrigation Practices ...
African Journals Online (AJOL)
Constraints and prospects of hand dug wells related to household irrigation were assessed in Hayelom watershed (~1045 ha), by evaluating groundwater suitability for irrigation, soil quality and impact of intervention. 181 hand dug wells have come into existence in the watershed due to intervention and benefiting about ...
Primordial black holes survive SN lensing constraints
García-Bellido, Juan; Clesse, Sébastien; Fleury, Pierre
2018-06-01
It has been claimed in [arxiv:1712.02240] that massive primordial black holes (PBH) cannot constitute all of the dark matter (DM), because their gravitational-lensing imprint on the Hubble diagram of type Ia supernovae (SN) would be incompatible with present observations. In this note, we critically review those constraints and find several caveats on the analysis. First of all, the constraints on the fraction α of PBH in matter seem to be driven by a very restrictive choice of priors on the cosmological parameters. In particular, the degeneracy between Ωm and α was ignored and thus, by fixing Ωm, transferred the constraining power of SN magnitudes to α. Furthermore, by considering more realistic physical sizes for the type-Ia supernovae, we find an effect on the SN lensing magnification distribution that leads to significantly looser constraints. Moreover, considering a wide mass spectrum of PBH, such as a lognormal distribution, further softens the constraints from SN lensing. Finally, we find that the fraction of PBH that could constitute DM today is bounded by fPBH < 1 . 09(1 . 38) , for JLA (Union 2.1) catalogs, and thus it is perfectly compatible with an all-PBH dark matter scenario in the LIGO band.
MatrixPlot: visualizing sequence constraints
DEFF Research Database (Denmark)
Gorodkin, Jan; Stærfeldt, Hans Henrik; Lund, Ole
1999-01-01
MatrixPlot: visualizing sequence constraints. Sub-title Abstract Summary : MatrixPlot is a program for making high-quality matrix plots, such as mutual information plots of sequence alignments and distance matrices of sequences with known three-dimensional coordinates. The user can add information...
Constraint-induced movement therapy after stroke
Kwakkel, G.; Veerbeek, J.M.; van Wegen, E.E.H.; Wolf, S.L.
2015-01-01
Constraint-induced movement therapy (CIMT) was developed to overcome upper limb impairments after stroke and is the most investigated intervention for the rehabilitation of patients. Original CIMT includes constraining of the non-paretic arm and task-oriented training. Modified versions also apply
Institutional and resource constraints that inhibit contractor ...
African Journals Online (AJOL)
Results show that contractors face institutional constraints (work allocation limitations, lack of performance incentives and high transaction costs, such as negotiation costs, the risk of a loss in work and contract default risk), cash flow problems, poor physical infrastructure and a lack of labour. It is expected that the promotion ...
Sustainability constraints on UK bioenergy development
International Nuclear Information System (INIS)
Thornley, Patricia; Upham, Paul; Tomei, Julia
2009-01-01
Use of bioenergy as a renewable resource is increasing in many parts of the world and can generate significant environmental, economic and social benefits if managed with due regard to sustainability constraints. This work reviews the environmental, social and economic constraints on key feedstocks for UK heat, power and transport fuel. Key sustainability constraints include greenhouse gas savings achieved for different fuels, land availability, air quality impacts and facility siting. Applying those constraints, we estimate that existing technologies would facilitate a sustainability constrained level of medium-term bioenergy/biofuel supply to the UK of 4.9% of total energy demand, broken down into 4.3% of heat demands, 4.3% of electricity, and 5.8% of transport fuel. This suggests that attempts to increase the supply above these levels could have counterproductive sustainability impacts in the absence of compensating technology developments or identification of additional resources. The barriers that currently prevent this level of supply being achieved have been analysed and classified. This suggests that the biggest policy impacts would be in stimulating the market for heat demand in rural areas, supporting feedstock prices in a manner that incentivised efficient use/maximum greenhouse gas savings and targeting investment capital that improves yield and reduces land-take.
Industrial capacity is not a constraint
International Nuclear Information System (INIS)
Walske, C.
1977-01-01
The improved rate at which nuclear power plants are likely to be ordered in the next two years will still be well below the annual level needed to meet official planning assumptions. Industry's capability is not a constraint but the government should be more positive on nuclear power, licensing and the fuel cycle. (author)
Hours Constraints Within and Between Jobs
Euwals, R.W.
1997-01-01
In the empirical literature on labour supply, several models are developed to incorporate constraints on working hours. These models do not address the question to which extent working hours are constrained within and between jobs. In this paper I investigate the effect of individual changes in
Management practices and production constraints of central ...
African Journals Online (AJOL)
management practices of central highland goats and their major constraints. ... tance to improve the goat production potential and livelihood of the farmers in the study ... ing the productivity and income from keeping goats, there is a study gap in ..... and day time, possibly increasing the chance of getting contagious diseases.
Near-Optimal Fingerprinting with Constraints
Directory of Open Access Journals (Sweden)
Gulyás Gábor György
2016-10-01
Full Text Available Several recent studies have demonstrated that people show large behavioural uniqueness. This has serious privacy implications as most individuals become increasingly re-identifiable in large datasets or can be tracked, while they are browsing the web, using only a couple of their attributes, called as their fingerprints. Often, the success of these attacks depends on explicit constraints on the number of attributes learnable about individuals, i.e., the size of their fingerprints. These constraints can be budget as well as technical constraints imposed by the data holder. For instance, Apple restricts the number of applications that can be called by another application on iOS in order to mitigate the potential privacy threats of leaking the list of installed applications on a device. In this work, we address the problem of identifying the attributes (e.g., smartphone applications that can serve as a fingerprint of users given constraints on the size of the fingerprint. We give the best fingerprinting algorithms in general, and evaluate their effectiveness on several real-world datasets. Our results show that current privacy guards limiting the number of attributes that can be queried about individuals is insufficient to mitigate their potential privacy risks in many practical cases.
Language-universal constraints on speech segmentation
Norris, D.; McQueen, J.M.; Cutler, A.; Butterfield, S.; Kearns, R.K.
2001-01-01
Two word-spotting experiments are reported that examine whether the Possible-Word Constraint (PWC; Norris, McQueen, Cutler & Butterfield, 1997) is a language-specific or language-universal strategy for the segmentation of continuous speech. The PWC disfavors parses which leave an impossible residue
Neuroplasticity in Constraint-Induced Movement Therapy
DEFF Research Database (Denmark)
Blicher, Jakob; Near, Jamie; Næss-Schmidt, Erhard
2014-01-01
In healthy subjects, decreasing GABA facilitates motor learning[1]. Recent studies, using PET[2], TMS[3-5], and pharmacological challenges[6], have pointed indirectly to a decrease in neuronal inhibitory activity after stroke. Therefore, we hypothesize that a suppression of GABA levels post strok...... might be beneficial to motor recovery during Constraint-Induced Movement Therapy (CIMT)....
Optimal Environmental Policy Differentials under Emissions Constraints
Florax, R.J.G.M.; Mulatu, A.; Withagen, C.A.A.M.
2007-01-01
Is there a case for preferential treatment of the exposed sector in an economy when compliance to an aggregate emissions constraint induced by an international environmental agreement is mandatory? This question is being debated in many countries in the context of the implementation of the Kyoto
An examination of constraints to wilderness visitation
Gary T. Green; J. Michael Bowker; Cassandra Y. Johnson; H. Ken Cordell; Xiongfei Wang
2007-01-01
Certain social groups appear notably less in wilderness visitation surveys than their population proportion. This study examines whether different social groups in American society (minorities, women, rural dwellers, low income and less educated populations) perceive more constraints to wilderness visitation than other groups. Logistic regressions were fit to data from...
Groundwater for sustainable development opportunities and constraints
International Nuclear Information System (INIS)
Abdel Rahman Attia, F.
1999-01-01
This paper discusses water resources availability and demand; concept and constraints of sustainable development; ground water protection. Water issues specific for arid zones and the network on ground water protection in the Arab region are discussed. Recommendations on ground water protection in arid zones are given
Borrowing constraints, multiple equilibria and monetary policy
Assenza, T.
2007-01-01
The appealing feature of Kiyotaki and Moore's Financial Accelerator model (Kiyotaki and Moore, 1997, 2002) is the linkage of asset price changes and borrowing constraints. This framework therefore is the natural vehicle to explore the net worth channel of the monetary transmission mechanism. In the
Choice within Constraints: Mothers and Schooling.
David, Miriam; Davies, Jackie; Edwards, Rosalind; Reay, Diane; Standing, Kay
1997-01-01
Explores, from a feminist perspective, the discourses of choice regarding how women make their choices as consumers in the education marketplace. It argues that mothers as parents are not free to choose but act within a range of constraints, i.e., their choices are limited by structural and moral possibilities in a patriarchal and racist society.…
Cognitive Dissonance Reduction as Constraint Satisfaction.
Shultz, Thomas R.; Lepper, Mark R.
1996-01-01
It is argued that the reduction of cognitive dissonance can be viewed as a constraint satisfaction problem, and a computational model of the process of consonance seeking is proposed. Simulations from this model matched psychological findings from the insufficient justification and free-choice paradigms of cognitive dissonance theory. (SLD)
Data Driven Constraints for the SVM
DEFF Research Database (Denmark)
Darkner, Sune; Clemmensen, Line Katrine Harder
2012-01-01
We propose a generalized data driven constraint for support vector machines exemplified by classification of paired observations in general and specifically on the human ear canal. This is particularly interesting in dynamic cases such as tissue movement or pathologies developing over time. Assum...
Reinforcement, Behavior Constraint, and the Overjustification Effect.
Williams, Bruce W.
1980-01-01
Four levels of the behavior constraint-reinforcement variable were manipulated: attractive reward, unattractive reward, request to perform, and a no-reward control. Only the unattractive reward and request groups showed the performance decrements that suggest the overjustification effect. It is concluded that reinforcement does not cause the…
Affordability Constraints in Major Defense Acquisitions
2016-11-01
memo, does not provide a detailed recipe for those who must produce quantitative affordability constraints. Enclosure 8 of the January 7, 2015 version...3.0’s full title includes “Achieving Dominant Capabilities 2015 Lot 2028 Lot 2038 Lot $0 $100 $200 $300 $400 $ 500 $600 $700 $800 $900 0 10000 20000
Perceptual Constraints on Infant Memory Retrieval.
Gerhardstein, Peter; Liu, Jane; Rovee-Collier, Carolyn
1998-01-01
Three experiments examined characteristics of a stimulus-cueing retrieval from long-term memory for 3-month olds. Used mobiles displaying either Qs (feature-present stimuli) or Os (feature-absent stimuli) and tested 24 hours later. Findings indicated that target-distractor similarity constraints, whether or not a feature-present stimulus, would…
On the canonical treatment of Lagrangian constraints
International Nuclear Information System (INIS)
Barbashov, B.M.
2001-01-01
The canonical treatment of dynamic systems with manifest Lagrangian constraints proposed by Berezin is applied to concrete examples: a special Lagrangian linear in velocities, relativistic particles in proper time gauge, a relativistic string in orthonormal gauge, and the Maxwell field in the Lorentz gauge
CONSTRAINTS AND PROBLEMS OF INTERNET SERVICES IN ...
African Journals Online (AJOL)
In spite of the benefits of the Internet to learning, teaching and research a number of difficulties still bedevil the provision of services in Nigeria. The objective of this study was to examine the constraints and problems of Internet Services at the Obafemi Awolowo University, Ile-Ife. Questionnaires were administered to ...
Ability or Finances as Constraints on Entrepreneurship?
DEFF Research Database (Denmark)
Andersen, Steffen; Meisner Nielsen, Kasper
2012-01-01
We use a natural experiment in Denmark to test the hypothesis that aspiring entrepreneurs face financial constraints because of low entrepreneurial quality. We identify 304 constrained entrepreneurs who start a business after receiving windfall wealth and examine the performance of these marginal...
Ability or Finances as Constraints on Entrepreneurship?
DEFF Research Database (Denmark)
Andersen, Steffen; Meisner Nielsen, Kasper
We use a natural experiment in Denmark to test the hypothesis that aspiring entrepreneurs face financial constraints because of low entrepreneurial quality. We identify 304 constrained entrepreneurs who start a business after receiving windfall wealth and examine the performance of these marginal...
Quantum centipedes with strong global constraint
Grange, Pascal
2017-06-01
A centipede made of N quantum walkers on a one-dimensional lattice is considered. The distance between two consecutive legs is either one or two lattice spacings, and a global constraint is imposed: the maximal distance between the first and last leg is N + 1. This is the strongest global constraint compatible with walking. For an initial value of the wave function corresponding to a localized configuration at the origin, the probability law of the first leg of the centipede can be expressed in closed form in terms of Bessel functions. The dispersion relation and the group velocities are worked out exactly. Their maximal group velocity goes to zero when N goes to infinity, which is in contrast with the behaviour of group velocities of quantum centipedes without global constraint, which were recently shown by Krapivsky, Luck and Mallick to give rise to ballistic spreading of extremal wave-front at non-zero velocity in the large-N limit. The corresponding Hamiltonians are implemented numerically, based on a block structure of the space of configurations corresponding to compositions of the integer N. The growth of the maximal group velocity when the strong constraint is gradually relaxed is explored, and observed to be linear in the density of gaps allowed in the configurations. Heuristic arguments are presented to infer that the large-N limit of the globally constrained model can yield finite group velocities provided the allowed number of gaps is a finite fraction of N.
Egalitarian Risk Sharing under Liquidity Constraints
Koster, M.; Boonen, T.
2014-01-01
Undertaking joint projects in practice involves a lot of uncertainty, especially when it comes to the final costs. This paper addresses the problem of sharing realized costs by the participants, subject to their indvidual liquidity constraints. If all cost levels can be accounted for, and it the
Constraints on the CP-Violating MSSM
Arbey, A; Godbole, R M; Mahmoudi, F
2016-01-01
We discuss the prospects for observing CP violation in the MSSM with six CP-violating phases, using a geometric approach to maximise CP-violating observables subject to the experimental upper bounds on electric dipole moments. We consider constraints from Higgs physics, flavour physics, the dark matter relic density and spin-independent scattering cross section with matter.
Constraints To Effective Community Development Projects Among ...
African Journals Online (AJOL)
The study focused on the perceived constraints to effective community development projects among rural households in Calabar agricultural zone of Cross River State, Nigeria. Data were collected with the aid of structured questionnaire from 104 randomly selected respondents in the study area. Data analysis was by the ...
Nuclear safety: an operational constraint or necessity
International Nuclear Information System (INIS)
Gauvenet, A.
1983-01-01
Different aspects of the nuclear safety in the operation of power stations are analysed. There is always a danger that safety is considered as a constraint at operator level, but it is essential that human factors and working conditions be taken into consideration [fr
Tilapia culture in Kuwait: constraints and solutions
Ridha, M.T.
2006-01-01
Tilapia farming in Kuwait is in its early stages. Slow growth, high production cost and poor demand are the major constraints to the expansion of tilapia culture in Kuwait. This article presents some suggestions for overcoming these problems to improve the economic feasibility of tilapia culture in Kuwait.
Constraints on low energy Compton scattering amplitudes
International Nuclear Information System (INIS)
Raszillier, I.
1979-04-01
We derive the constraints and correlations of fairly general type for Compton scattering amplitudes at energies below photoproduction threshold and fixed momentum transfer, following from (an upper bound on) the corresponding differential cross section above photoproduction threshold. The derivation involves the solution of an extremal problem in a certain space of vector - valued analytic functions. (author)
A Microkernel Architecture for Constraint Programming
Michel, Laurent; Van Hentenryck, Pascal
2014-01-01
This paper presents a microkernel architecture for constraint programming organized around a number of small number of core functionalities and minimal interfaces. The architecture contrasts with the monolithic nature of many implementations. Experimental results indicate that the software engineering benefits are not incompatible with runtime efficiency.
On the canonical treatment of Lagrangian constraints
International Nuclear Information System (INIS)
Barbashov, B.M.
2001-01-01
The canonical treatment of dynamic systems with manifest Lagrangian constraints proposed by Berezin is applied to concrete examples: a specific Lagrangian linear in velocities, relativistic particles in proper time gauge, a relativistic string in orthonormal gauge, and the Maxwell field in the Lorentz gauge
Confluence Modulo Equivalence in Constraint Handling Rules
DEFF Research Database (Denmark)
Christiansen, Henning; Kirkeby, Maja Hanne
2014-01-01
Previous results on confluence for Constraint Handling Rules, CHR, are generalized to take into account user-defined state equivalence relations. This allows a much larger class of programs to enjoy the ad- vantages of confluence, which include various optimization techniques and simplified...
Constraint Embedding Technique for Multibody System Dynamics
Woo, Simon S.; Cheng, Michael K.
2011-01-01
Multibody dynamics play a critical role in simulation testbeds for space missions. There has been a considerable interest in the development of efficient computational algorithms for solving the dynamics of multibody systems. Mass matrix factorization and inversion techniques and the O(N) class of forward dynamics algorithms developed using a spatial operator algebra stand out as important breakthrough on this front. Techniques such as these provide the efficient algorithms and methods for the application and implementation of such multibody dynamics models. However, these methods are limited only to tree-topology multibody systems. Closed-chain topology systems require different techniques that are not as efficient or as broad as those for tree-topology systems. The closed-chain forward dynamics approach consists of treating the closed-chain topology as a tree-topology system subject to additional closure constraints. The resulting forward dynamics solution consists of: (a) ignoring the closure constraints and using the O(N) algorithm to solve for the free unconstrained accelerations for the system; (b) using the tree-topology solution to compute a correction force to enforce the closure constraints; and (c) correcting the unconstrained accelerations with correction accelerations resulting from the correction forces. This constraint-embedding technique shows how to use direct embedding to eliminate local closure-loops in the system and effectively convert the system back to a tree-topology system. At this point, standard tree-topology techniques can be brought to bear on the problem. The approach uses a spatial operator algebra approach to formulating the equations of motion. The operators are block-partitioned around the local body subgroups to convert them into aggregate bodies. Mass matrix operator factorization and inversion techniques are applied to the reformulated tree-topology system. Thus in essence, the new technique allows conversion of a system with
Constraints on perturbative RG flows in six dimensions
Energy Technology Data Exchange (ETDEWEB)
Stergiou, Andreas [Department of Physics, Yale University,217 Prospect St, New Haven, CT 06520 (United States); Stone, David [INFN, Sezione di Roma,Piazzale A. Moro 2, I-00185 Roma (Italy); Vitale, Lorenzo G. [Institut de Théorie des Phènoménes Physiques, EPFL,Route Cantonale, CH-1015 Lausanne (Switzerland)
2016-08-01
When conformal field theories (CFTs) are perturbed by marginally relevant deformations, renormalization group (RG) flows ensue that can be studied with perturbative methods, at least as long as they remain close to the original CFT. In this work we study such RG flows in the vicinity of six-dimensional unitary CFTs. Neglecting effects of scalar operators of dimension two and four, we use Weyl consistency conditions to prove the a-theorem in perturbation theory, and establish that scale implies conformal invariance. We identify a quantity that monotonically decreases in the flow to the infrared due to unitarity, showing that it does not agree with the one studied recently in the literature on the six-dimensional ϕ{sup 3} theory.
Toward making the constraint hypersurface an attractor in free evolution
International Nuclear Information System (INIS)
Fiske, David R.
2004-01-01
When constructing numerical solutions to systems of evolution equations subject to a constraint, one must decide what role the constraint equations will play in the evolution system. In one popular choice, known as free evolution, a simulation is treated as a Cauchy problem, with the initial data constructed to satisfy the constraint equations. This initial data are then evolved via the evolution equations with no further enforcement of the constraint equations. The evolution, however, via the discretized evolution equations introduce constraint violating modes at the level of truncation error, and these constraint violating modes will behave in a formalism dependent way. This paper presents a generic method for incorporating the constraint equations into the evolution equations so that the off-constraint dynamics are biased toward the constraint satisfying solutions
Constraints and Creativity in NPD - Testing the Impact of 'Late Constraints'
DEFF Research Database (Denmark)
Onarheim, Balder; Valgeirsdóttir, Dagný
experiment was conducted, involving 12 teams of industrial designers from three different countries, each team working on two 30 minutes design tasks. In one condition all constraints were given at the start, and in the other one new radical constraint was added after 12 minutes. The output from all 24 tasks......The aim of the presented work is to investigate how the timing of project constraints can influence the creativity of the output in New Product Development (NPD) projects. When seeking to produce a creative output, is it beneficial to know all constraints when initiating a project...... was assessed for creativity using the Consensual Assessment Technique (CAT), and a comparative within-subjects analysis found no significant different between the two conditions. Controlling for task and assessor a small but non-significant effect was found, in favor of the ‘late constraint’ condition. Thus...
Czech Academy of Sciences Publication Activity Database
Červinka, Michal; Kanzow, Ch.; Schwartz, A.
2016-01-01
Roč. 160, č. 1 (2016), s. 353-377 ISSN 0025-5610 R&D Projects: GA ČR GAP402/12/1309; GA ČR GA15-00735S Institutional support: RVO:67985556 Keywords : Cardinality constraints * Constraint qualifications * Optimality conditions * KKT conditions * Strongly stationary points Subject RIV: BA - General Mathematics Impact factor: 2.446, year: 2016 http://library.utia.cas.cz/separaty/2016/MTR/cervinka-0461165.pdf
Medical image segmentation by means of constraint satisfaction neural network
International Nuclear Information System (INIS)
Chen, C.T.; Tsao, C.K.; Lin, W.C.
1990-01-01
This paper applies the concept of constraint satisfaction neural network (CSNN) to the problem of medical image segmentation. Constraint satisfaction (or constraint propagation), the procedure to achieve global consistency through local computation, is an important paradigm in artificial intelligence. CSNN can be viewed as a three-dimensional neural network, with the two-dimensional image matrix as its base, augmented by various constraint labels for each pixel. These constraint labels can be interpreted as the connections and the topology of the neural network. Through parallel and iterative processes, the CSNN will approach a solution that satisfies the given constraints thus providing segmented regions with global consistency
Optimisation and constraints - a view from ICRP
International Nuclear Information System (INIS)
Dunster, H.J.
1994-01-01
The optimisation of protection has been the major policy underlying the recommendations of the International Commission on Radiological Protection for more than 20 years. In earlier forms, the concept can be traced back to 1951. Constraints are more recent, appearing in their present form only in the 1990 recommendations of the Commission. The requirement to keep all exposures as low as reasonably achievable applies to both normal and potential exposures. The policy and the techniques are well established for normal exposures, i.e. exposures that are certain to occur. The application to potential exposures, i.e. exposures that have a probability of occurring that is less than unity, is more difficult and is still under international discussion. Constraints are needed to limit the inequity associated with the use of collective dose in cost-benefit analysis and to provide a margin to protect individuals who may be exposed to more than one source. (author)
Constraints on stellar evolution from pulsations
International Nuclear Information System (INIS)
Cox, A.N.
1984-01-01
Consideration of the many types of intrinsic variable stars, that is, those that pulsate, reveals that perhaps a dozen classes can indicate some constraints that affect the results of stellar evolution calculations, or some interpretations of observations. Many of these constraints are not very strong or may not even be well defined yet. The author discusses the case for six classes: classical Cepheids with their measured Wesselink radii, the observed surface effective temperatures of the known eleven double-mode Cepheids, the pulsation periods and measured surface effective temperatures of three R CrB variables, the delta Scuti variable VZ Cnc with a very large ratio of its two observed periods, the nonradial oscillations of the Sun, and the period ratios of the newly discovered double-mode RR Lyrae variables. (Auth.)
Microbial diversity arising from thermodynamic constraints
Großkopf, Tobias; Soyer, Orkun S
2016-01-01
The microbial world displays an immense taxonomic diversity. This diversity is manifested also in a multitude of metabolic pathways that can utilise different substrates and produce different products. Here, we propose that these observations directly link to thermodynamic constraints that inherently arise from the metabolic basis of microbial growth. We show that thermodynamic constraints can enable coexistence of microbes that utilise the same substrate but produce different end products. We find that this thermodynamics-driven emergence of diversity is most relevant for metabolic conversions with low free energy as seen for example under anaerobic conditions, where population dynamics is governed by thermodynamic effects rather than kinetic factors such as substrate uptake rates. These findings provide a general understanding of the microbial diversity based on the first principles of thermodynamics. As such they provide a thermodynamics-based framework for explaining the observed microbial diversity in different natural and synthetic environments. PMID:27035705
Microbial diversity arising from thermodynamic constraints.
Großkopf, Tobias; Soyer, Orkun S
2016-11-01
The microbial world displays an immense taxonomic diversity. This diversity is manifested also in a multitude of metabolic pathways that can utilise different substrates and produce different products. Here, we propose that these observations directly link to thermodynamic constraints that inherently arise from the metabolic basis of microbial growth. We show that thermodynamic constraints can enable coexistence of microbes that utilise the same substrate but produce different end products. We find that this thermodynamics-driven emergence of diversity is most relevant for metabolic conversions with low free energy as seen for example under anaerobic conditions, where population dynamics is governed by thermodynamic effects rather than kinetic factors such as substrate uptake rates. These findings provide a general understanding of the microbial diversity based on the first principles of thermodynamics. As such they provide a thermodynamics-based framework for explaining the observed microbial diversity in different natural and synthetic environments.
Locality constraints and 2D quasicrystals
International Nuclear Information System (INIS)
Socolar, J.E.S.
1990-01-01
The plausible assumption that long-range interactions between atoms are negligible in a quasicrystal leaks to the study of tilings that obey constraints on the local configurations of tiles. The theory of such constraints (called matching rules) for 2D quasicrystal tilings is reviewed here. Different types of matching rules are defined and examples of tilings obeying them are given where known. The role of tile decoration is discussed and is shown to be significant in at least two cases (octagonal and dodecagonal duals of periodic 4-grids and 6-grids). A new result is introduced: a constructive procedure is described for generating weak matching rules for tilings with N-fold symmetry, for any N that is either a prime number or twice a prime number. The physics associated with weak matching rules, results on local growth rules, and the case of icosahedral symmetry are all briefly discussed. (author). 29 refs, 4 figs
Neutrino mass constraints on β decay
International Nuclear Information System (INIS)
Ito, Takeyasu M.; Prezeau, Gary
2005-01-01
Using the general connection between the upper limit on the neutrino mass and the upper limits on certain types of non-standard-model interactions that can generate loop corrections to the neutrino mass, we derive constraints on some non-standard-model d→ue - ν interactions. When cast into limits on n→pe - ν coupling constants, our results yield constraints on scalar and tensor weak interactions improved by more than an order of magnitude over the current experimental limits. When combined with the existing limits, our results yield vertical bar C S /C V vertical bar or approx. 5x10 -3 , vertical bar C S ' /C V vertical bar or approx. 5x10 -3 , vertical bar C T /C A vertical bar -2 , and vertical bar C T ' /C A vertical bar -2
Constraints from jet calculus on quark recombination
International Nuclear Information System (INIS)
Jones, L.M.; Lassila, K.E.; Willen, D.
1979-01-01
Within the QCD jet calculus formalism, we deduce an equation describing recombination of quarks and antiquarks into mesons within a quark or gluon jet. This equation relates the recombination function R(x 1 ,x 2 ,x) used in current literature to the fragmentation function for producing that same meson out of the parton initiating the jet. We submit currently used recombination functions to our consistency test, taking as input mainly the u-quark fragmentation data into π + mesons, but also s-quark fragmentation into K - mesons. The constraint is well satisfied at large Q 2 for large moments. Our results depend on one parameter, Q 0 2 , the constraint equation being satisfied for small values of this parameter
Financial Constraints and Nominal Price Rigidities
DEFF Research Database (Denmark)
Menno, Dominik Francesco; Balleer, Almut; Hristov, Nikolay
This paper investigates how financial market imperfections and the frequency of price adjustment interact. Based on new firm-level evidence for Germany, we document that financially constrained firms adjust prices more often than their unconstrained counterparts, both upwards and downwards. We show...... that these empirical patterns are consistent with a partial equilibrium menu-cost model with a working capital constraint. We then use the model to show how the presence of financial frictions changes profits and the price distribution of firms compared to a model without financial frictions. Our results suggest...... that tighter financial constraints are associated with higher nominal rigidities, higher prices and lower output. Moreover, in response to aggregate shocks, aggregate price rigidity moves substantially, the response of inflation is dampened, while output reacts more in the presence of financial frictions...
Automated constraint placement to maintain pile shape
Hsu, Shu-Wei
2012-11-01
We present a simulation control to support art-directable stacking designs by automatically adding constraints to stabilize the stacking structure. We begin by adapting equilibrium analysis in a local scheme to find "stable" objects of the stacking structure. Next, for stabilizing the structure, we pick suitable objects from those passing the equilibrium analysis and then restrict their DOFs by managing the insertion of constraints on them. The method is suitable for controlling stacking behavior of large scale. Results show that our control method can be used in varied ways for creating plausible animation. In addition, the method can be easily implemented as a plug-in into existing simulation solvers without changing the fundamental operations of the solvers. © 2012 ACM.
Fundamental constraints on some event data
International Nuclear Information System (INIS)
Watson, I.A.
1986-01-01
A modified version of Searle's theory of the structure of human action has been explained and applied to man machine interaction. The comprehensiveness of the theory has been demonstrated, in particular its explanation of human performance and that its consistency with current theories of human error for which it provides an overall setting. The importance of the mental component of human error is highlighted and the constraints that this puts on the collection analysis and use of human error data. Examples have been given to illustrate and apply the theory ranging from considerations of the tenuousness of the link between safety goals and data to simple valve operations. Two approaches which recognise the constraints shown by the theory have been explained. (orig./DG)
Constraints on backreaction in dust universes
International Nuclear Information System (INIS)
Raesaenen, Syksy
2006-01-01
We study backreaction in dust universes using exact equations which do not rely on perturbation theory, concentrating on theoretical and observational constraints. In particular, we discuss the recent suggestion (Kolb et al 2005 Preprint hep-th/0503117) that superhorizon perturbations could explain present-day accelerated expansion as a useful example which can be ruled out. We note that a backreaction explanation of late-time acceleration will have to involve spatial curvature and subhorizon perturbations
Constraints on Large-Block Shareholders
Clifford G. Holderness; Dennis P. Sheehan
1998-01-01
Corporate managers who own a majority of the common stock in their company or who represent another firm owning such an interest appear to be less constrained than managers of diffusely held firms, yet their power to harm minority shareholders must be circumscribed by some organizational or legal arrangements. Empirical investigations reveal that boards of directors in majority-owned firms are little different from firms with diffuse stock ownership. Another source of constraints on a majorit...
Constraints on fermion mixing with exotics
International Nuclear Information System (INIS)
Nardi, E.; Tommasini, D.
1991-11-01
We analyze the constraints on the mixing angles of the standard fermions with new heavy particles with exotic SU(2) x U(1) quantum number assignments (left-handed singlets or right-handed doublets), that appear in many extensions of the electroweak theory. The updated Charged Current and Neutral Current experimental data, including also the recent Z-peak measurements, are considered. The results of the global analysis of all these data are then presented
On the covariantization of the Chiral constraints
International Nuclear Information System (INIS)
Wotzasek, Clovis; Abreu, E.M.C. de; Neves, C.
1994-01-01
We show that a complete covariantization of the chiral constraint in the Floreanini-Jackiw necessitates an infinite number of auxiliary Wess-Zumino fields otherwise the covariantization is only partial and unable to remove the nonlocality in the chiral boson operator. We comment on recent works that claim to obtain covariantization through the use of Batalin-Fradklin-Tyutin method, that uses just one Wess-Zumino field. (author)
Hours Constraints Within and Between Jobs
Euwals, R.W.
1997-01-01
In the empirical literature on labour supply, several models are developed to incorporate constraints on working hours. These models do not address the question to which extent working hours are constrained within and between jobs. In this paper I investigate the effect of individual changes in labour supply preferences on actual working hours. The availability of subjective information on the individual’s preferred working hours gives direct measures on the degree of adjustment of working ho...
Prominent Constraints Faced by Government Managers.
1983-06-01
organizations have varied cultures and missions. 8 There has been little researc -h on the identification of these constraints and the effective...Additionally, in the current environment they4 15 are responsible to set the rate schedule for various services provided to NAVAIR, and to market ...NAVAIR. They are paid on the basis of work to be performed. This allows a better cost accounting system, but results in some marketing behavior by the
Work Hours Constraints: Impacts and Policy Implications
Constant, Amelie F.; Otterbach, Steffen
2011-01-01
If individuals reveal their preference as consumers, then they are taken seriously. What happens if individuals, as employees, reveal their preferences in working hours? And what happens if there is a misalignment between actual hours worked and preferred hours, the so-called work hours constraints? How does this affect the productivity of workers, their health, and overall life satisfaction? Labor supply and corresponding demand are fundamental to production. Labor economists know for long t...
Embedded System Synthesis under Memory Constraints
DEFF Research Database (Denmark)
Madsen, Jan; Bjørn-Jørgensen, Peter
1999-01-01
This paper presents a genetic algorithm to solve the system synthesis problem of mapping a time constrained single-rate system specification onto a given heterogeneous architecture which may contain irregular interconnection structures. The synthesis is performed under memory constraints, that is......, the algorithm takes into account the memory size of processors and the size of interface buffers of communication links, and in particular the complicated interplay of these. The presented algorithm is implemented as part of the LY-COS cosynthesis system....
Least Squares Problems with Absolute Quadratic Constraints
Directory of Open Access Journals (Sweden)
R. Schöne
2012-01-01
Full Text Available This paper analyzes linear least squares problems with absolute quadratic constraints. We develop a generalized theory following Bookstein's conic-fitting and Fitzgibbon's direct ellipse-specific fitting. Under simple preconditions, it can be shown that a minimum always exists and can be determined by a generalized eigenvalue problem. This problem is numerically reduced to an eigenvalue problem by multiplications of Givens' rotations. Finally, four applications of this approach are presented.
Information Constraints and Financial Aid Policy
Judith Scott-Clayton
2012-01-01
One justification for public support of higher education is that prospective students, particularly those from underprivileged groups, lack complete information about the costs and benefits of a college degree. Beyond financial considerations, students may also lack information about what they need to do academically to prepare for and successfully complete college. Yet until recently, college aid programs have typically paid little attention to students' information constraints, and the comp...
Cosmological constraints with clustering-based redshifts
Kovetz, Ely D.; Raccanelli, Alvise; Rahman, Mubdi
2017-07-01
We demonstrate that observations lacking reliable redshift information, such as photometric and radio continuum surveys, can produce robust measurements of cosmological parameters when empowered by clustering-based redshift estimation. This method infers the redshift distribution based on the spatial clustering of sources, using cross-correlation with a reference data set with known redshifts. Applying this method to the existing Sloan Digital Sky Survey (SDSS) photometric galaxies, and projecting to future radio continuum surveys, we show that sources can be efficiently divided into several redshift bins, increasing their ability to constrain cosmological parameters. We forecast constraints on the dark-energy equation of state and on local non-Gaussianity parameters. We explore several pertinent issues, including the trade-off between including more sources and minimizing the overlap between bins, the shot-noise limitations on binning and the predicted performance of the method at high redshifts, and most importantly pay special attention to possible degeneracies with the galaxy bias. Remarkably, we find that once this technique is implemented, constraints on dynamical dark energy from the SDSS imaging catalogue can be competitive with, or better than, those from the spectroscopic BOSS survey and even future planned experiments. Further, constraints on primordial non-Gaussianity from future large-sky radio-continuum surveys can outperform those from the Planck cosmic microwave background experiment and rival those from future spectroscopic galaxy surveys. The application of this method thus holds tremendous promise for cosmology.
Distributed Unmixing of Hyperspectral Datawith Sparsity Constraint
Khoshsokhan, S.; Rajabi, R.; Zayyani, H.
2017-09-01
Spectral unmixing (SU) is a data processing problem in hyperspectral remote sensing. The significant challenge in the SU problem is how to identify endmembers and their weights, accurately. For estimation of signature and fractional abundance matrices in a blind problem, nonnegative matrix factorization (NMF) and its developments are used widely in the SU problem. One of the constraints which was added to NMF is sparsity constraint that was regularized by L1/2 norm. In this paper, a new algorithm based on distributed optimization has been used for spectral unmixing. In the proposed algorithm, a network including single-node clusters has been employed. Each pixel in hyperspectral images considered as a node in this network. The distributed unmixing with sparsity constraint has been optimized with diffusion LMS strategy, and then the update equations for fractional abundance and signature matrices are obtained. Simulation results based on defined performance metrics, illustrate advantage of the proposed algorithm in spectral unmixing of hyperspectral data compared with other methods. The results show that the AAD and SAD of the proposed approach are improved respectively about 6 and 27 percent toward distributed unmixing in SNR=25dB.
Constraints based analysis of extended cybernetic models.
Mandli, Aravinda R; Venkatesh, Kareenhalli V; Modak, Jayant M
2015-11-01
The cybernetic modeling framework provides an interesting approach to model the regulatory phenomena occurring in microorganisms. In the present work, we adopt a constraints based approach to analyze the nonlinear behavior of the extended equations of the cybernetic model. We first show that the cybernetic model exhibits linear growth behavior under the constraint of no resource allocation for the induction of the key enzyme. We then quantify the maximum achievable specific growth rate of microorganisms on mixtures of substitutable substrates under various kinds of regulation and show its use in gaining an understanding of the regulatory strategies of microorganisms. Finally, we show that Saccharomyces cerevisiae exhibits suboptimal dynamic growth with a long diauxic lag phase when growing on a mixture of glucose and galactose and discuss on its potential to achieve optimal growth with a significantly reduced diauxic lag period. The analysis carried out in the present study illustrates the utility of adopting a constraints based approach to understand the dynamic growth strategies of microorganisms. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Current constraints on the cosmic growth history
International Nuclear Information System (INIS)
Bean, Rachel; Tangmatitham, Matipon
2010-01-01
We present constraints on the cosmic growth history with recent cosmological data, allowing for deviations from ΛCDM as might arise if cosmic acceleration is due to modifications to general relativity or inhomogeneous dark energy. We combine measures of the cosmic expansion history, from Type 1a supernovae, baryon acoustic oscillations, and the cosmic microwave background (CMB), with constraints on the growth of structure from recent galaxy, CMB, and weak lensing surveys along with integated Sachs Wolfe-galaxy cross correlations. Deviations from ΛCDM are parameterized by phenomenological modifications to the Poisson equation and the relationship between the two Newtonian potentials. We find modifications that are present at the time the CMB is formed are tightly constrained through their impact on the well-measured CMB acoustic peaks. By contrast, constraints on late-time modifications to the growth history, as might arise if modifications are related to the onset of cosmic acceleration, are far weaker, but remain consistent with ΛCDM at the 95% confidence level. For these late-time modifications we find that differences in the evolution on large and small scales could provide an interesting signature by which to search for modified growth histories with future wide angular coverage, large scale structure surveys.
Use of dose constraints in medical exposure
International Nuclear Information System (INIS)
Mutanga, N. V. T.
2013-04-01
Medical-related radiation is the largest source of controllable radiation exposure to humans and it accounts for more than 95% of radiation exposure from man-made sources. Medical exposure to radiation is exposure incurred by patients as part of their own medical or dental diagnosis or treatment; by persons, other than those occupationally exposed, knowingly, while voluntarily helping in the support and comfort of patients; and by volunteers in a programme of biomedical research involving their exposure. Because it is planned exposure, medical exposure has to conform to a set of principles of protection that apply equally to all controllable exposure situations: the principle of justification, the principle of optimisation of protection, and the principle of application of limits on maximum doses in planned situations. In this study the concept of dose constraints is being scrutinized to see if it can be applied in medical exposures and the benefits of such restrictions. Dose constraints can only be applied to exposure to persons voluntary helping in the support and comfort of patients as well as volunteers in the programme of biomedical research. There are no dose constraints for patients but the concept of reference levels applies. (au)
Constraints on grand unified superstring theories
International Nuclear Information System (INIS)
Ellis, J.; Lopez, J.L.; Nanopoulos, D.V.; Houston Advanced Research Center
1990-01-01
We evaluate some constraints on the construction of grand unified superstring theories (GUSTs) using higher level Kac-Moody algebras on the world-sheet. In the most general formulation of the heterotic string in four dimensions, an analysis of the basic GUST model-building constraints, including a realistic hidden gauge group, reveals that there are no E 6 models and any SO(10) models can only exist at level-5. Also, any such SU(5) models can exist only for levels 4≤k≤19. These SO(10) and SU(5) models risk having many large, massless, phenomenologically troublesome representations. We also show that with a suitable hidden sector gauge group, it is possible to avoid free light fractionally charged particles, which are endemic to string derived models. We list all such groups and their representations for the flipped SU(5)xU(1) model. We conclude that a sufficiently binding hidden sector gauge group becomes a basic model-building constraint. (orig.)
Constraints on stellar evolution from pulsations
International Nuclear Information System (INIS)
Cox, A.N.
1983-01-01
Consideration of the many types of intrinsic variable stars, that is, those that pulsate, reveals that perhaps a dozen classes can indicate some constraints that affect the results of stellar evolution calculations, or some interpretations of observations. Many of these constraints are not very strong or may not even be well defined yet. In this review we discuss only the case for six classes: classical Cepheids with their measured Wesselink radii, the observed surface effective temperatures of the known eleven double-mode Cepheids, the pulsation periods and measured surface effective temperatures of three R CrB variables, the delta Scuti variable VZ Cnc with a very large ratio of its two observed periods, the nonradial oscillations of our sun, and the period ratios of the newly discovered double-mode RR Lyrae variables. Unfortunately, the present state of knowledge about the exact compositions; mass loss and its dependence on the mass, radius, luminosity, and composition; ;and internal mixing processes, as well as sometimes the more basic parameters such as luminosities and surface effective temperatures prevent us from applying strong constraints for every case where currently the possibility exists
New constraints for canonical general relativity
International Nuclear Information System (INIS)
Reisenberger, M.P.
1995-01-01
Ashtekar's canonical theory of classical complex Euclidean GR (no Lorentzian reality conditions) is found to be invariant under the full algebra of infinitesimal 4-diffeomorphisms, but non-invariant under some finite proper 4-diffeos when the densitized dreibein, E a i , is degenerate. The breakdown of 4-diffeo invariance appears to be due to the inability of the Ashtekar Hamiltonian to generate births and deaths of E flux loops (leaving open the possibility that a new 'causality condition' forbidding the birth of flux loops might justify the non-invariance of the theory).A fully 4-diffeo invariant canonical theory in Ashtekar's variables, derived from Plebanski's action, is found to have constraints that are stronger than Ashtekar's for rank E< 2. The corresponding Hamiltonian generates births and deaths of E flux loops.It is argued that this implies a finite amplitude for births and deaths of loops in the physical states of quantum GR in the loop representation, thus modifying this (partly defined) theory substantially.Some of the new constraints are second class, leading to difficulties in quantization in the connection representation. This problem might be overcome in a very nice way by transforming to the classical loop variables, or the 'Faraday line' variables of Newman and Rovelli, and then solving the offending constraints.Note that, though motivated by quantum considerations, the present paper is classical in substance. (orig.)
Tail Risk Constraints and Maximum Entropy
Directory of Open Access Journals (Sweden)
Donald Geman
2015-06-01
Full Text Available Portfolio selection in the financial literature has essentially been analyzed under two central assumptions: full knowledge of the joint probability distribution of the returns of the securities that will comprise the target portfolio; and investors’ preferences are expressed through a utility function. In the real world, operators build portfolios under risk constraints which are expressed both by their clients and regulators and which bear on the maximal loss that may be generated over a given time period at a given confidence level (the so-called Value at Risk of the position. Interestingly, in the finance literature, a serious discussion of how much or little is known from a probabilistic standpoint about the multi-dimensional density of the assets’ returns seems to be of limited relevance. Our approach in contrast is to highlight these issues and then adopt throughout a framework of entropy maximization to represent the real world ignorance of the “true” probability distributions, both univariate and multivariate, of traded securities’ returns. In this setting, we identify the optimal portfolio under a number of downside risk constraints. Two interesting results are exhibited: (i the left- tail constraints are sufficiently powerful to override all other considerations in the conventional theory; (ii the “barbell portfolio” (maximal certainty/ low risk in one set of holdings, maximal uncertainty in another, which is quite familiar to traders, naturally emerges in our construction.
Constraint theory, singular lagrangians and multitemporal dynamics
International Nuclear Information System (INIS)
Lusanna, L.
1988-01-01
Singular Lagrangians and constraint theory permeate theoretical physics, as shown by the relevance of gauge theories, string models and general relativity. Their study used finite---dimensional models as a guide to develop the theory, but their main use was in classical field theory, due to the necessity of understanding their quantization. The covariant quantization of singular Lagrangians led to the BRST approach and to the theory of the effective action. On the other hand their phase---space formulation, culminated with the BFV approach for first class, second class and reducible constraints. It, in turn, gave new insights in the theory of singular Lagrangians and constraints and in their cohomological aspects. However the Hamiltonian approach to field theory is highly nontrivial, is open to criticism due to its problems with locality, geometry and manifest covariance and its canonical quantization has still to be developed, because there is no proof of the renormalizability of the Schroedinger representation of field theory. This paper discusses how, notwithstanding these developments, there is still a big amount of ambiguity at every level of the theory
Orthology and paralogy constraints: satisfiability and consistency.
Lafond, Manuel; El-Mabrouk, Nadia
2014-01-01
A variety of methods based on sequence similarity, reconciliation, synteny or functional characteristics, can be used to infer orthology and paralogy relations between genes of a given gene family G. But is a given set C of orthology/paralogy constraints possible, i.e., can they simultaneously co-exist in an evolutionary history for G? While previous studies have focused on full sets of constraints, here we consider the general case where C does not necessarily involve a constraint for each pair of genes. The problem is subdivided in two parts: (1) Is C satisfiable, i.e. can we find an event-labeled gene tree G inducing C? (2) Is there such a G which is consistent, i.e., such that all displayed triplet phylogenies are included in a species tree? Previous results on the Graph sandwich problem can be used to answer to (1), and we provide polynomial-time algorithms for satisfiability and consistency with a given species tree. We also describe a new polynomial-time algorithm for the case of consistency with an unknown species tree and full knowledge of pairwise orthology/paralogy relationships, as well as a branch-and-bound algorithm in the case when unknown relations are present. We show that our algorithms can be used in combination with ProteinOrtho, a sequence similarity-based orthology detection tool, to extract a set of robust orthology/paralogy relationships.
Canonical and D-transformations in Theories with Constraints
Gitman, Dmitri M.
1995-01-01
A class class of transformations in a super phase space (we call them D-transformations) is described, which play in theories with second-class constraints the role of ordinary canonical transformations in theories without constraints.
Branch and bound algorithms to solve semiring constraint satisfaction problems
CSIR Research Space (South Africa)
Leenen, L
2008-12-01
Full Text Available The Semiring Constraint Satisfaction Problem (SCSP) framework is a popular approach for the representation of partial constraint satisfaction problems. Considerable research has been done in solving SCSPs, but limited work has been done in building...
Differential constraints and exact solutions of nonlinear diffusion equations
International Nuclear Information System (INIS)
Kaptsov, Oleg V; Verevkin, Igor V
2003-01-01
The differential constraints are applied to obtain explicit solutions of nonlinear diffusion equations. Certain linear determining equations with parameters are used to find such differential constraints. They generalize the determining equations used in the search for classical Lie symmetries
A combined constraint handling framework: an empirical study
DEFF Research Database (Denmark)
Si, Chengyong; Hu, Junjie; Lan, Tian
2017-01-01
This paper presents a new combined constraint handling framework (CCHF) for solving constrained optimization problems (COPs). The framework combines promising aspects of different constraint handling techniques (CHTs) in different situations with consideration of problem characteristics. In order...
Pension fund's illiquid assets allocation under liquidity and capital constraints
Broeders, Dirk; Jansen, Kristy; Werker, Bas
2017-01-01
This paper empirically assesses the impact of liquidity and capital constraints on the allocation of defined benefit pension funds to illiquid assets. Liquidity constraints result from short-term pension payments and collateral requirements on derivatives. Capital constraints follow from the requirement to retain sufficient capital to absorb unexpected losses. Liability duration and hedging affect the allocation to illiquid assets through both these constraints. First, we find a hump-shaped i...
ON Integrated Chance Constraints in ALM for Pension Funds
Youssouf A. F. Toukourou; Fran\\c{c}ois Dufresne
2015-01-01
We discuss the role of integrated chance constraints (ICC) as quantitative risk constraints in asset and liability management (ALM) for pension funds. We define two types of ICC: the one period integrated chance constraint (OICC) and the multiperiod integrated chance constraint (MICC). As their names suggest, the OICC covers only one period whereas several periods are taken into account with the MICC. A multistage stochastic linear programming model is therefore developed for this purpose and...
DELPHI ANALYSIS OF CONSTRAINTS TO MAIZE PRODUCTION IN ...
African Journals Online (AJOL)
A descriptive Delphi study was conducted to: identify constraints to maize production on SNL from the perspectives of crop researchers, extension officers and farmers; categorise the constraints; rank them in order of importance; and identify ways of addressing them. A total of 33 constraint items were identified and ...
Extended Set Constraints and Tree Grammar Abstraction of Programs
DEFF Research Database (Denmark)
Rosendahl, Mads; Gallagher, John Patrick
2011-01-01
Set constraints are relations between sets of ground terms or trees. This paper presents two main contributions: firstly we consider an extension of the systems of set constraints to include a tuple constructor, and secondly we construct a simplified solution procedure for set constraints. We...
A comparison of debt and primary-deficit constraints
Ribeiro, M.P.; Beetsma, R.; Schabert, A.
2008-01-01
This paper compares constraints on the public debt with constraints on the primary deficit. The analysis takes into account how an optimizing government reacts to the different constraints when deciding on a spending and borrowing plan. We find that the economy behaves similarly under both
Constraint programming for modelling and solving modal satisfiability
Brand, S.; Gennari, R.; de Rijke, M.
2003-01-01
We explore to what extent and how efficiently constraint programmingcan be used in the context of automated reasoning for modal logics. We encode modal satisfiability problems as constraint satisfactionproblems with non-boolean domains, together with suitable constraints.Experiments show that the
Pension fund's illiquid assets allocation under liquidity and capital constraints
Broeders, Dirk; Jansen, Kristy; Werker, Bas
2017-01-01
This paper empirically assesses the impact of liquidity and capital constraints on the allocation of defined benefit pension funds to illiquid assets. Liquidity constraints result from short-term pension payments and collateral requirements on derivatives. Capital constraints follow from the
Relating chronology protection and unitarity through holography
Czech Academy of Sciences Publication Activity Database
Raeymaekers, Joris; Van den Bleeken, D.; Vercnocke, B.
2010-01-01
Roč. 2010, č. 4 (2010), s. 1-9 ISSN 1126-6708 Grant - others:EUROHORC(XE) EYI/07/E010 Institutional research plan: CEZ:AV0Z10100502 Keywords : AdS-CFT correspondence * models of quantum gravity * classical theories of gravity Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 6.049, year: 2010 http://www.springerlink.com/content/g5q123uj51218371/
Black hole unitarity and antipodal entanglement
't Hooft, Gerard
Hawking particles emitted by a black hole are usually found to have thermal spectra, if not exactly, then by a very good approximation. Here, we argue differently. It was discovered that spherical partial waves of in-going and out-going matter can be described by unitary evolution operators
Cluster formulation in the dual topological unitarization
International Nuclear Information System (INIS)
Hossain, M.
1979-02-01
The work of Chiu, Hossain, and Tow is generalized by incorporating the no double counting condition and the t/sub min/ effect in the integral equations for the Reggeon and the Pomeron. The relation between the no double counting condition and the average cluster separation is derived, and a test is proposed to determine the correct counting. It is shown that the t/sub min/ effect is quite important in determining the Regge parameters. The model predicts a relation between five physical quantities: the Pomeron intercept (α/sub p/ 0 ) and slope (α/sub p/'), the magnitude (k) and the exponential dependence (b) of the triple-Regge vertex, and the ratio of Pomeron to Reggeon residues (c) at t = 0. The solutions obtained are well within the range of acceptable values. A reasonable solution is, for example, α/sub p/ 0 = .92, α/sub p/' = .2, b = 1.6, k = 12.9, and c = 0.91. It is found that cuts are present in both the Reggeon and the Pomeron amplitudes, and their contributions are small compared to the leading poles. 27 references
Unitarity and predictiveness in new Higgs inflation
Fumagalli, Jacopo; Mooij, Sander; Postma, Marieke
2018-03-01
In new Higgs inflation the Higgs kinetic terms are non-minimally coupled to the Einstein tensor, allowing the Higgs field to play the role of the inflaton. The new interaction is non-renormalizable, and the model only describes physics below some cutoff scale. Even if the unknown UV physics does not affect the tree level inflaton potential significantly, it may still enter at loop level and modify the running of the Standard Model (SM) parameters. This is analogous to what happens in the original model for Higgs inflation. A key difference, though, is that in new Higgs inflation the inflationary predictions are sensitive to this running. Thus the boundary conditions at the EW scale as well as the unknown UV completion may leave a signature on the inflationary parameters. However, this dependence can be evaded if the kinetic terms of the SM fermions and gauge fields are non-minimally coupled to gravity as well. Our approach to determine the model's UV dependence and the connection between low and high scale physics can be used in any particle physics model of inflation.
Unitarity and irreversibility in chaotic systems
International Nuclear Information System (INIS)
Hasegawa, H.H.; Saphir, W.C.
1992-01-01
We analyze the spectral properties of the Perron-Frobenius operator U, associated with some simple highly chaotic maps. We obtain a spectral decomposition of U in terms of generalized eigenfunctions of U and its adjoint. The corresponding eigenvalues are related to the decay rates of correlation functions and have magnitude less than one, so that physically measurable quantities manifestly approach equilibrium. To obtain decaying eigenstates of unitary and isometric operators it is necessary to extend the Hilbert-space formulation of dynamical systems. We describe and illustrate a method to obtain the decomposition explicitly
Dynamical dark energy: Current constraints and forecasts
Upadhye, Amol; Ishak, Mustapha; Steinhardt, Paul J.
2005-09-01
We consider how well the dark energy equation of state w as a function of redshift z will be measured using current and anticipated experiments. We use a procedure which takes fair account of the uncertainties in the functional dependence of w on z, as well as the parameter degeneracies, and avoids the use of strong prior constraints. We apply the procedure to current data from the Wilkinson Microwave Anisotropy Probe, Sloan Digital Sky Survey, and the supernova searches, and obtain results that are consistent with other analyses using different combinations of data sets. The effects of systematic experimental errors and variations in the analysis technique are discussed. Next, we use the same procedure to forecast the dark energy constraints achievable by the end of the decade, assuming 8 years of Wilkinson Microwave Anisotropy Probe data and realistic projections for ground-based measurements of supernovae and weak lensing. We find the 2σ constraints on the current value of w to be Δw0(2σ)=0.20, and on dw/dz (between z=0 and z=1) to be Δw1(2σ)=0.37. Finally, we compare these limits to other projections in the literature. Most show only a modest improvement; others show a more substantial improvement, but there are serious concerns about systematics. The remaining uncertainty still allows a significant span of competing dark energy models. Most likely, new kinds of measurements, or experiments more sophisticated than those currently planned, are needed to reveal the true nature of dark energy.
Constraints on stress-energy perturbations in general relativity
International Nuclear Information System (INIS)
Traschen, J.
1985-01-01
Conditions are found for the existence of integral constraints on stress-energy perturbations in general relativity. The integral constraints can be thought of as a general-relativistic generalization of the conservation of energy and momentum of matter perturbations in special relativity. The constraints are stated in terms of a vector field V, and the Robertson-Walker spacetimes are shown to have such constraint vectors. Although in general V is not a Killing vector, in a vacuum spacetime the constraint vectors are precisely the Killing vectors
[The Nature and Issues of Drug Addiction Treatment under Constraint].
Quirion, Bastien
This article is exploring different forms of constraint that are exerted in the field of drug addiction treatment. The objective of this article is to establish benchmarks and to stimulate reflection about the ethical and clinical implications of those constraints in the field of drug addiction treatment. This article is presenting a critical review of different forms of constraint that can be exerted in Canada in regard to the treatment of drug addiction. In the first section of the article, a definition of therapeutic intervention is proposed, that includes the dimension of power, which justifies the importance of considering the coercive aspects of treatment. The second section, which represents the core section of the paper, is devoted to the presentation of different levels of constraint that can be distinguished in regard to drug addicts who are under treatment. Three levels of constraint are exposed: judicial constraint, institutional constraint and relational constraint. The coercive aspect of treatment can then be recognized as a combination of all tree levels of constraint. Judicial constraint refers to any form of constraint in which the court or the judge is imposing or recommending treatment. This particular level of constraint can take different forms, such as therapeutic remands, conditions of a probation order, conditions of a conditional sentence of imprisonment, and coercive treatment such as the ones provided through drug courts. Institutional constraint refers to any form of constraint exerted within any institutional setting, such as correctional facilities and programs offered in community. Correctional facilities being limited by their own specific mission, it might have a major impact on the way the objectives of treatment are defined. Those limitations can then be considered as a form of constraint, in which drug users don't have much space to express their personal needs. Finally, relational constraint refers to any form of constraint in
Nonlinear Model Predictive Control with Constraint Satisfactions for a Quadcopter
Wang, Ye; Ramirez-Jaime, Andres; Xu, Feng; Puig, Vicenç
2017-01-01
This paper presents a nonlinear model predictive control (NMPC) strategy combined with constraint satisfactions for a quadcopter. The full dynamics of the quadcopter describing the attitude and position are nonlinear, which are quite sensitive to changes of inputs and disturbances. By means of constraint satisfactions, partial nonlinearities and modeling errors of the control-oriented model of full dynamics can be transformed into the inequality constraints. Subsequently, the quadcopter can be controlled by an NMPC controller with the updated constraints generated by constraint satisfactions. Finally, the simulation results applied to a quadcopter simulator are provided to show the effectiveness of the proposed strategy.
Epidemics on adaptive networks with geometric constraints
Shaw, Leah; Schwartz, Ira
2008-03-01
When a population is faced with an epidemic outbreak, individuals may modify their social behavior to avoid exposure to the disease. Recent work has considered models in which the contact network is rewired dynamically so that susceptibles avoid contact with infectives. We consider extensions in which the rewiring is subject to constraints that preserve key properties of the social network structure. Constraining to a fixed degree distribution destroys previously observed bistable behavior. The most effective rewiring strategy is found to depend on the spreading rate.
Constraints on the braneworld from compact stars
Energy Technology Data Exchange (ETDEWEB)
Felipe, R.G. [Instituto Politecnico de Lisboa, ISEL, Instituto Superior de Engenharia de Lisboa, Lisboa (Portugal); Instituto Superior Tecnico, Universidade de Lisboa, Departamento de Fisica, Centro de Fisica Teorica de Particulas, CFTP, Lisboa (Portugal); Paret, D.M. [Universidad de la Habana, Departamento de Fisica General, Facultad de Fisica, La Habana (Cuba); Martinez, A.P. [Instituto de Cibernetica, Matematica y Fisica (ICIMAF), La Habana (Cuba); Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Nucleares, Mexico, Distrito Federal (Mexico)
2016-06-15
According to the braneworld idea, ordinary matter is confined on a three-dimensional space (brane) that is embedded in a higher-dimensional space-time where gravity propagates. In this work, after reviewing the limits coming from general relativity, finiteness of pressure and causality on the brane, we derive observational constraints on the braneworld parameters from the existence of stable compact stars. The analysis is carried out by solving numerically the brane-modified Tolman-Oppenheimer-Volkoff equations, using different representative equations of state to describe matter in the star interior. The cases of normal dense matter, pure quark matter and hybrid matter are considered. (orig.)
Mean-Reverting Portfolio With Budget Constraint
Zhao, Ziping; Palomar, Daniel P.
2018-05-01
This paper considers the mean-reverting portfolio design problem arising from statistical arbitrage in the financial markets. We first propose a general problem formulation aimed at finding a portfolio of underlying component assets by optimizing a mean-reversion criterion characterizing the mean-reversion strength, taking into consideration the variance of the portfolio and an investment budget constraint. Then several specific problems are considered based on the general formulation, and efficient algorithms are proposed. Numerical results on both synthetic and market data show that our proposed mean-reverting portfolio design methods can generate consistent profits and outperform the traditional design methods and the benchmark methods in the literature.
Phloem physics: mechanisms, constraints, and perspectives.
Jensen, Kaare H
2018-04-13
Plants have evolved specialized vascular tissues for the distribution of energy, water, nutrients, and for communication. The phloem transports sugars from photosynthetic source regions (e.g. mature leaves) to sugar sinks (e.g. developing tissues such as buds, flowers, roots). Moreover, chemical signals such as hormones, RNAs and proteins also move in the phloem. Basic physical processes strongly limit phloem anatomy and function. This paper provides an overview of recent research and perspectives on phloem biomechanics and the physical constraints relevant to sugar transport in plants. Copyright © 2018 Elsevier Ltd. All rights reserved.
Unique supply function equilibrium with capacity constraints
International Nuclear Information System (INIS)
Holmberg, Paer
2008-01-01
Consider a market where producers submit supply functions to a procurement auction with uncertain demand, e.g. an electricity auction. In the Supply Function Equilibrium (SFE), every firm commits to the supply function that maximises expected profit in the one-shot game given the supply functions of competitors. A basic weakness of the SFE is the presence of multiple equilibria. This paper shows that with (i) symmetric producers, (ii) perfectly inelastic demand, (iii) a price cap, and (iv) capacity constraints that bind with a positive probability, there exists a unique, symmetric SFE. (author)
Variational calculus with constraints on general algebroids
Energy Technology Data Exchange (ETDEWEB)
Grabowska, Katarzyna [Physics Department, Division of Mathematical Methods in Physics, University of Warsaw, Hoza 69, 00-681 Warszawa (Poland); Grabowski, Janusz [Institute of Mathematics, Polish Academy of Sciences, Sniadeckich 8, PO Box 21, 00-956 Warszawa (Poland)], E-mail: konieczn@fuw.edu.pl, E-mail: jagrab@impan.gov.pl
2008-05-02
Variational calculus on a vector bundle E equipped with a structure of a general algebroid is developed, together with the corresponding analogs of Euler-Lagrange equations. Constrained systems are introduced in the variational and geometrical settings. The constrained Euler-Lagrange equations are derived for analogs of holonomic, vakonomic and nonholonomic constraints. This general model covers the majority of first-order Lagrangian systems which are present in the literature and reduces to the standard variational calculus and the Euler-Lagrange equations in classical mechanics for E = TM.
Black hole entropy, universality, and horizon constraints
International Nuclear Information System (INIS)
Carlip, Steven
2006-01-01
To ask a question about a black hole in quantum gravity, one must restrict initial or boundary data to ensure that a black hole is actually present. For two-dimensional dilaton gravity, and probably a much wider class of theories, I show that the imposition of a 'stretched horizon' constraint modifies the algebra of symmetries at the horizon, allowing the use of conformal field theory techniques to determine the asymptotic density of states. The result reproduces the Bekenstein-Hawking entropy without any need for detailed assumptions about the microscopic theory. Horizon symmetries may thus offer an answer to the problem of universality of black hole entropy
Black hole entropy, universality, and horizon constraints
Energy Technology Data Exchange (ETDEWEB)
Carlip, Steven [Department of Physics, University of California, Davis, CA 95616 (United States)
2006-03-01
To ask a question about a black hole in quantum gravity, one must restrict initial or boundary data to ensure that a black hole is actually present. For two-dimensional dilaton gravity, and probably a much wider class of theories, I show that the imposition of a 'stretched horizon' constraint modifies the algebra of symmetries at the horizon, allowing the use of conformal field theory techniques to determine the asymptotic density of states. The result reproduces the Bekenstein-Hawking entropy without any need for detailed assumptions about the microscopic theory. Horizon symmetries may thus offer an answer to the problem of universality of black hole entropy.
Variational constraints for electrical-impedance tomography
International Nuclear Information System (INIS)
Berryman, J.G.; Kohn, R.V.
1990-01-01
The task of electrical-impedance tomography is to invert boundary measurements for the conductivity distribution of a body. This inverse problem can be formulated so the primary data are the measured powers dissipated across injection electrodes. Then, since these powers are minima of the pertinent (dual) variational principles, feasibility constraints can be found for the nonlinear inversion problem. When power may be measured accurately, the existence of these dual variational principles implies that any exact solution must lie at a point of intersection of the two feasibility boundaries
Soft Budget Constraints in Professional Football
DEFF Research Database (Denmark)
Storm, Rasmus K.; Nielsen, Klaus
2012-01-01
European professional football clubs go out of business even though they operate chronically on the edge of financial collapse? The paper argues that the paradox can be explained by the fact that professional football clubs operate within soft budget constraints in a way which is similar to the role...... of large companies in socialist economies – a phenomenon which was first identified by the Hungarian Economist János Kornai. More generally, it is argued that our understanding of the peculiar economics of professional team sports can be enhanced significantly by applying the soft budget constrain concept...
Intelligence Constraints on Terrorist Network Plots
Woo, Gordon
Since 9/11, the western intelligence and law enforcement services have managed to interdict the great majority of planned attacks against their home countries. Network analysis shows that there are important intelligence constraints on the number and complexity of terrorist plots. If two many terrorists are involved in plots at a given time, a tipping point is reached whereby it becomes progressively easier for the dots to be joined and for the conspirators to be arrested, and for the aggregate evidence to secure convictions. Implications of this analysis are presented for the campaign to win hearts and minds.
Overlapping constraint for variational surface reconstruction
DEFF Research Database (Denmark)
Aanæs, Henrik; Solem, J.E.
2005-01-01
In this paper a counter example, illustrating a shortcoming in most variational formulations for 3D surface estimation, is presented. The nature of this shortcoming is a lack of an overlapping constraint. A remedy for this shortcoming is presented in the form of a penalty function with an analysi...... of the effects of this function on surface motion. For practical purposes, this will only have minor influence on current methods. However, the insight provided in the analysis is likely to influence future developments in the field of variational surface reconstruction....
Variational calculus with constraints on general algebroids
International Nuclear Information System (INIS)
Grabowska, Katarzyna; Grabowski, Janusz
2008-01-01
Variational calculus on a vector bundle E equipped with a structure of a general algebroid is developed, together with the corresponding analogs of Euler-Lagrange equations. Constrained systems are introduced in the variational and geometrical settings. The constrained Euler-Lagrange equations are derived for analogs of holonomic, vakonomic and nonholonomic constraints. This general model covers the majority of first-order Lagrangian systems which are present in the literature and reduces to the standard variational calculus and the Euler-Lagrange equations in classical mechanics for E = TM
CMB constraints on running non-Gaussianity
Oppizzi, Filippo; Liguori, Michele; Renzi, Alessandro; Arroja, Frederico; Bartolo, Nicola
2017-01-01
We develop a complete set of tools for CMB forecasting, simulation and estimation of primordial running bispectra, arising from a variety of curvaton and single-field (DBI) models of Inflation. We validate our pipeline using mock CMB running non-Gaussianity realizations and test it on real data by obtaining experimental constraints on the $f_{\\rm NL}$ running spectral index, $n_{\\rm NG}$, using WMAP 9-year data. Our final bounds (68\\% C.L.) read $-0.3< n_{\\rm NG}
Institutional opportunities and constraints to biomass development
International Nuclear Information System (INIS)
Costello, R.; Finnell, J.
1998-01-01
This paper examines a number of institutional opportunities and constraints applicable to biomass as well as other renewable energy technologies. Technological progress that improves performance or increases system efficiencies can open doors to deployment; however, market success depends on overcoming the institutional challenges that these technologies will face. It can be far more difficult to put into place the necessary institutional mechanisms which will drive these commercialization efforts. The keys to the successful implementation of energy technologies and, in particular, biomass power technologies, are issues that can be categorized as: (1) regulatory; (2) financial; (3) infrastructural; and (4) perceptual. (author)
Total-variation regularization with bound constraints
International Nuclear Information System (INIS)
Chartrand, Rick; Wohlberg, Brendt
2009-01-01
We present a new algorithm for bound-constrained total-variation (TV) regularization that in comparison with its predecessors is simple, fast, and flexible. We use a splitting approach to decouple TV minimization from enforcing the constraints. Consequently, existing TV solvers can be employed with minimal alteration. This also makes the approach straightforward to generalize to any situation where TV can be applied. We consider deblurring of images with Gaussian or salt-and-pepper noise, as well as Abel inversion of radiographs with Poisson noise. We incorporate previous iterative reweighting algorithms to solve the TV portion.
Constraints on Gauge Field Production during Inflation
DEFF Research Database (Denmark)
Nurmi, Sami; Sloth, Martin Snoager
2014-01-01
In order to gain new insights into the gauge field couplings in the early universe, we consider the constraints on gauge field production during inflation imposed by requiring that their effect on the CMB anisotropies are subdominant. In particular, we calculate systematically the bispectrum...... of the primordial curvature perturbation induced by the presence of vector gauge fields during inflation. Using a model independent parametrization in terms of magnetic non-linearity parameters, we calculate for the first time the contribution to the bispectrum from the cross correlation between the inflaton...
Big bang nucleosynthesis constraints on bulk neutrinos
International Nuclear Information System (INIS)
Goh, H.S.; Mohapatra, R.N.
2002-01-01
We examine the constraints imposed by the requirement of successful nucleosynthesis on models with one large extra hidden space dimension and a single bulk neutrino residing in this dimension. We solve the Boltzmann kinetic equation for the thermal distribution of the Kaluza-Klein modes and evaluate their contribution to the energy density at the big bang nucleosynthesis epoch to constrain the size of the extra dimension R -1 ≡μ and the parameter sin 2 2θ which characterizes the mixing between the active and bulk neutrinos
Gamma ray constraints on decaying dark matter
DEFF Research Database (Denmark)
Cirelli, M.; Moulin, E.; Panci, P.
2012-01-01
We derive new bounds on decaying dark matter from the gamma ray measurements of (i) the isotropic residual (extragalactic) background by Fermi and (ii) the Fornax galaxy cluster by H.E.S.S. We find that those from (i) are among the most stringent constraints currently available, for a large range...... of dark matter masses and a variety of decay modes, excluding half-lives up to similar to 10(26) to few 10(27) seconds. In particular, they rule out the interpretation in terms of decaying dark matter of the e(+/-) spectral features in PAMELA, Fermi and H.E.S.S., unless very conservative choices...
Participation Constraints in the Stock Market
DEFF Research Database (Denmark)
Andersen, Steffen; Meisner Nielsen, Kasper
2011-01-01
We use a natural experiment to investigate the impact of participation constraints on individuals' decisions to invest in the stock market. Unexpected inheritance due to sudden deaths results in exogenous variation in financial wealth, and allows us to examine whether fixed entry and ongoing...... participation costs cause non-participation. We have three key findings. First, windfall wealth has a positive effect on participation. Second, the majority of households do not react to sizeable windfalls by entering the stock market, but hold on to substantial safe assets—even over longer horizons. Third...
Low energy constraints and scalar leptoquarks⋆
Directory of Open Access Journals (Sweden)
Fajfer Svjetlana
2014-01-01
Full Text Available The presence of a colored weak doublet scalar state with mass below 1 TeV can provide an explanation of the observed branching ratios in B → D(∗τντ decays. Constraints coming from Z → bb̄, muon g − 2, lepton flavor violating decays are derived. The colored scalar is accommodated within 45 representation of SU(5 group of unification. We show that presence of color scalar can improve mass relations in the up-type quark sector mass. Impact of the colored scalar embedding in 45-dimensional representation of SU(5 on low-energy phenomenology is also presented.
IAEA '77: between politics and factual constraints
International Nuclear Information System (INIS)
Freytag, A.
1976-01-01
The IAEA's organization of its 20th General Conference at Rio de Janeiro clearly underlined the importance of a comprehensive international transfer of nuclear technology. Despite all efforts to keep the Agency out of general political confrontations, the Conference was tinged politically by the PLO and South Africa problems. Besides the next five year program, which was agreed upon in the light of existing factual constraints, the support and control functions of the IAEA and next year's Salzburg Fuel Cycle Conference were other main topics of discussion. The 1977 IAEA budget was approved at a level of 43.5 million, the General Fund at 6.5 million. (orig.) [de
Mission Implementation Constraints on Planetary Muon Radiography
Jones, Cathleen E.; Kedar, Sharon; Naudet, Charles; Webb, Frank
2011-01-01
Cost: Use heritage hardware, especially use a tested landing system to reduce cost (Phoenix or MSL EDL stage). The sky crane technology delivers higher mass to the surface and enables reaching targets at higher elevation, but at a higher mission cost. Rover vs. Stationary Lander: Rover-mounted instrument enables tomography, but the increased weight of the rover reduces the allowable payload weight. Mass is the critical design constraint for an instrument for a planetary mission. Many factors that are minor factors or do not enter into design considerations for terrestrial operation are important for a planetary application. (Landing site, diurnal temperature variation, instrument portability, shock/vibration)
Modeling Network Transition Constraints with Hypergraphs
DEFF Research Database (Denmark)
Harrod, Steven
2011-01-01
Discrete time dynamic graphs are frequently used to model multicommodity flows or activity paths through constrained resources, but simple graphs fail to capture the interaction effects of resource transitions. The resulting schedules are not operationally feasible, and return inflated objective...... values. A directed hypergraph formulation is derived to address railway network sequencing constraints, and an experimental problem sample solved to estimate the magnitude of objective inflation when interaction effects are ignored. The model is used to demonstrate the value of advance scheduling...... of train paths on a busy North American railway....
Evaluation of uranium resources. Problems and constraints
International Nuclear Information System (INIS)
Williams, R.M.
1979-01-01
Growing awareness that the era of cheap energy is over has led to current efforts by governments and international organizations to examine the question of the adequacy of energy resources on a global scale. Despite the relative success of the NEA and the IAEA efforts in the study of world uranium supply, there is a need for such studies to become still more comprehensive and broader in scope. A basic problem exists with respect to the lack of a universally accepted set of resource terms by which to classify resource estimates once they are made. Often voids exist in international assessments because of insufficient data with respect to known resources and occasionally because of a lack of expertise to make the required estimates. With respect to the assessment of undiscovered uranium resources, major constraints are the relatively embryonic state of methodology for assessment of undiscovered resources and the fact that the inventory of basic geology, geochemical, and geophysical data is either incomplete or non-existent in many parts of the world. Finally, once resource estimates are made, there is often an unclear understanding about when and at what rate the resources can be made available. Hopefully, current efforts will lead to a solution to some of the principal problems and constraints which may be impeding progress toward an expansion and improvement of world uranium resource assessments. (author)
Movement constraints on interpersonal coordination and communication.
Tolston, Michael T; Shockley, Kevin; Riley, Michael A; Richardson, Michael J
2014-10-01
The present study investigated how constraining movement affects interpersonal coordination and joint cognitive performance. Pairs of participants worked cooperatively to solve picture-puzzle tasks in which they conversed to identify differences between pictures in 3 degree-of-constraint conditions: both participants were free to move their hands (free-free; FF); both participants' hands were restrained (restrained-restrained; RR); and the hands of 1 participant were free while the hands of the other participant were restrained (free-restrained; FR). Eye tracking data were collected, and movement was measured at the waist, hand, and head. Data were analyzed using Cross-Recurrence Quantification Analysis (CRQ). Postural sway coordination, gaze coordination, and task performance were predicted to be highest in FF, followed by RR, and then by FR. Results showed the asymmetric FR condition generally exhibited lesser degrees of coordination than the symmetric Conditions FF and RR, and that the patterning of coordination in the symmetric conditions varied across the measured body segments. These results demonstrate that movement restraints affect not only interpersonal postural coordination, but also joint attention. Additionally, significant positive relationships were found between task performance and total amount of anterior-posterior movement measured at the head, hand and waist; number of utterances; and number of differences pairs found in the puzzles. These findings indicate a relationship between movement and task performance consistent with the hypotheses that both interpersonal coordination and cognitive performance are sensitive to local action constraints.
Constraints on particle physics from cosmology
International Nuclear Information System (INIS)
Schramm, D.N.; Charlton, J.C.
1986-01-01
Cosmology and particle physics have become symbiotic in their relationship. In the past, developments in physics have been used to explain astrophysics problems. Recently, cosmology also has been able to place constraints on particle properties and these constraints can be tested by experiment. Thus, the flow of information at the interface of particle physics and cosmology is no longer just one-way. (Astronomy is no longer a parasite of physics.) Many examples of the interchange are described in this review. The timeline of cosmology is rapidly filling in as later events find their explanations in earlier events. In this review, the authors mention what is known about each epoch and show how it might constrain the particle models. Since a great deal of effort is devoted currently to the study of the dark matter problem, special emphasis will be placed on this issue. This study of dark matter and galaxy formation will allow us to draw upon much of what was discussed in earlier epochs. This review draws heavily on a previous review by the authors
Stochastic population dynamics under resource constraints
Energy Technology Data Exchange (ETDEWEB)
Gavane, Ajinkya S., E-mail: ajinkyagavane@gmail.com; Nigam, Rahul, E-mail: rahul.nigam@hyderabad.bits-pilani.ac.in [BITS Pilani Hyderabad Campus, Shameerpet, Hyd - 500078 (India)
2016-06-02
This paper investigates the population growth of a certain species in which every generation reproduces thrice over a period of predefined time, under certain constraints of resources needed for survival of population. We study the survival period of a species by randomizing the reproduction probabilities within a window at same predefined ages and the resources are being produced by the working force of the population at a variable rate. This randomness in the reproduction rate makes the population growth stochastic in nature and one cannot predict the exact form of evolution. Hence we study the growth by running simulations for such a population and taking an ensemble averaged over 500 to 5000 such simulations as per the need. While the population reproduces in a stochastic manner, we have implemented a constraint on the amount of resources available for the population. This is important to make the simulations more realistic. The rate of resource production then is tuned to find the rate which suits the survival of the species. We also compute the mean life time of the species corresponding to different resource production rate. Study for these outcomes in the parameter space defined by the reproduction probabilities and rate of resource production is carried out.
Instabilities constraint and relativistic mean field parametrization
International Nuclear Information System (INIS)
Sulaksono, A.; Kasmudin; Buervenich, T.J.; Reinhard, P.-G.; Maruhn, J.A.
2011-01-01
Two parameter sets (Set 1 and Set 2) of the standard relativistic mean field (RMF) model plus additional vector isoscalar nonlinear term, which are constrained by a set of criteria 20 determined by symmetric nuclear matter stabilities at high densities due to longitudinal and transversal particle–hole excitation modes are investigated. In the latter parameter set, δ meson and isoscalar as well as isovector tensor contributions are included. The effects in selected finite nuclei and nuclear matter properties predicted by both parameter sets are systematically studied and compared with the ones predicted by well-known RMF parameter sets. The vector isoscalar nonlinear term addition and instability constraints have reasonably good effects in the high-density properties of the isoscalar sector of nuclear matter and certain finite nuclei properties. However, even though the δ meson and isovector tensor are included, the incompatibility with the constraints from some experimental data in certain nuclear properties at saturation point and the excessive stiffness of the isovector nuclear matter equation of state at high densities as well as the incorrect isotonic trend in binding the energies of finite nuclei are still encountered. It is shown that the problem may be remedied if we introduce additional nonlinear terms not only in the isovector but also in the isoscalar vectors. (author)
Observational Constraints for Modeling Diffuse Molecular Clouds
Federman, S. R.
2014-02-01
Ground-based and space-borne observations of diffuse molecular clouds suggest a number of areas where further improvements to modeling efforts is warranted. I will highlight those that have the widest applicability. The range in CO fractionation caused by selective isotope photodissociation, in particular the large 12C16O/13C16O ratios observed toward stars in Ophiuchus, is not reproduced well by current models. Our ongoing laboratory measurements of oscillator strengths and predissociation rates for Rydberg transitions in CO isotopologues may help clarify the situtation. The CH+ abundance continues to draw attention. Small scale structure seen toward ζ Per may provide additional constraints on the possible synthesis routes. The connection between results from optical transitions and those from radio and sub-millimeter wave transitions requires further effort. A study of OH+ and OH toward background stars reveals that these species favor different environments. This brings to focus the need to model each cloud along the line of sight separately, and to allow the physical conditions to vary within an individual cloud, in order to gain further insight into the chemistry. Now that an extensive set of data on molecular excitation is available, the models should seek to reproduce these data to place further constraints on the modeling results.
Legal, ethical,and economic constraints
International Nuclear Information System (INIS)
Libassi, F.P.; Donaldson, L.F.
1980-01-01
This paper considers the legal, ethical, and economic constraints to developing a comprehensive knowledge of the biological effects of ionizing radiation. These constraints are not fixed and immutable; rather they are determined by the political process. Political issues cannot be evaded. The basic objective of developing a comprehensive knowledge about the biological effects of ionizing radiation exists as an objective not only because we wish to add to the store of human knowledge but also because we have important use for that knowledge. It will assist our decision-makers to make choices that affect us all. These choices require both hard factual information and application of political judgment. Research supplies some of the hard factual information and should be as free as possible from political influence in its execution. At the same time, the political choices that must be made influence the direction and nature of the research program as a whole. Similarly, the legal, ethical, and economic factors that constrain our ability to expand knowledge through research reflect a judgment by political agents that values other than expansion of knowledge should be recognized and given effect
Heat exchanger networks design with constraints
International Nuclear Information System (INIS)
Amidpur, M.; Zoghi, A.; Nasiri, N.
2000-01-01
So far there have been two approaches to the problem of heat recovery system design where stream matching constraints exist. The first approach involves mathematical techniques for solving the combinational problem taking due recognition of the constraints. These methodologies are now efficient, still suffer from the problem of taking a significant amount of control and direction away from the designer. The second approach based upon so called pinch technology and involves the use of adaptation of standard problem table algorithm. Unfortunately, the proposed methodologies are not very easy to understand, therefore they fail to provide the insight and generally associated with these approaches. Here, a new pinch based methodology is presented. In this method, we modified the traditional numerical targeting procedure-problem table algorithm which is stream cascade table. Unconstrained groups are established by using of artificial intelligence method such that they have minimum utility consumption among different alternatives. Each group is an individual network, therefore, traditional optimization, used in pinch technology, should be employed. By transferring energy between groups heat recovery can be maximized, then each group designs individually and finally networks combine together. One of the advantages of using this method is simple targeting and easy networks-design. Besides the approach has the potential using of new network design methods such as dual temperature approach, flexible pinch design, pseudo pinch design. It is hoped that this methodology provides insight easy network design
Hydrostatic equilibrium of stars without electroneutrality constraint
Krivoruchenko, M. I.; Nadyozhin, D. K.; Yudin, A. V.
2018-04-01
The general solution of hydrostatic equilibrium equations for a two-component fluid of ions and electrons without a local electroneutrality constraint is found in the framework of Newtonian gravity theory. In agreement with the Poincaré theorem on analyticity and in the context of Dyson's argument, the general solution is demonstrated to possess a fixed (essential) singularity in the gravitational constant G at G =0 . The regular component of the general solution can be determined by perturbation theory in G starting from a locally neutral solution. The nonperturbative component obtained using the method of Wentzel, Kramers and Brillouin is exponentially small in the inner layers of the star and grows rapidly in the outward direction. Near the surface of the star, both components are comparable in magnitude, and their nonlinear interplay determines the properties of an electro- or ionosphere. The stellar charge varies within the limits of -0.1 to 150 C per solar mass. The properties of electro- and ionospheres are exponentially sensitive to variations of the fluid densities in the central regions of the star. The general solutions of two exactly solvable stellar models without a local electroneutrality constraint are also presented.
Cosmological constraints on the neutron lifetime
Energy Technology Data Exchange (ETDEWEB)
Salvati, L.; Pagano, L.; Melchiorri, A. [Physics Department, Università di Roma ' ' La Sapienza' ' , Piazzale Aldo Moro 2, 00185, Rome (Italy); Consiglio, R., E-mail: laura.salvati@roma1.infn.it, E-mail: luca.pagano@roma1.infn.it, E-mail: rconsiglio@na.infn.it, E-mail: alessandro.melchiorri@roma1.infn.it [Physics Department, Università di Napoli ' ' Federico II' ' , Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy)
2016-03-01
We derive new constraints on the neutron lifetime based on the recent Planck 2015 observations of temperature and polarization anisotropies of the CMB. Under the assumption of standard Big Bang Nucleosynthesis, we show that Planck data constrains the neutron lifetime to τ{sub n} = (907±69) [s] at 68% c.l.. Moreover, by including the direct measurements of primordial Helium abundance of Aver et al. (2015) and Izotov et al. (2014), we show that cosmological data provide the stringent constraints τ{sub n} = (875±19) [s] and τ{sub n} = (921±11) [s] respectively. The latter appears to be in tension with neutron lifetime value quoted by the Particle Data Group (τ{sub n} = (880.3±1.1) [s]). Future CMB surveys as COrE+, in combination with a weak lensing survey as EUCLID, could constrain the neutron lifetime up to a ∼ 6 [s] precision.
Emerging carbon constraints for corporate risk management
International Nuclear Information System (INIS)
Busch, Timo; Hoffmann, Volker H.
2007-01-01
While discussions about global sustainability challenges abound, the financial risks that they incur, albeit important, have received less attention. We suggest that corporate risk assessments should include sustainability-related aspects, especially with relation to the natural environment, and encompass the flux of critical materials within a company's value chain. Such a comprehensive risk assessment takes into account input- as well as output-related factors. With this paper, we focus on the flux of carbon and define carbon constraints that emerge due to the disposition of fossil fuels in the input dimension and due to direct and indirect climate change effects in the output dimension. We review the literature regarding the financial consequences of carbon constraints on the macroeconomic, sector, and company level. We conclude that: a) financial consequences seem to be asymmetrically distributed between and within sectors, b) the individual risk exposure of companies depends on the intensity of and dependency on carbon-based materials and energy, and c) financial markets have only started to incorporate these aspects in their valuations. This paper ends with recommendations on how to incorporate our results in an integrated carbon risk management framework. (author)
Condensation with two constraints and disorder
Barré, J.; Mangeolle, L.
2018-04-01
We consider a set of positive random variables obeying two additive constraints, a linear and a quadratic one; these constraints mimic the conservation laws of a dynamical system. In the simplest setting, without disorder, it is known that such a system may undergo a ‘condensation’ transition, whereby one random variable becomes much larger than the others; this transition has been related to the spontaneous appearance of non linear localized excitations in certain nonlinear chains, called breathers. Motivated by the study of breathers in a disordered discrete nonlinear Schrödinger equation, we study different instances of this problem in presence of a quenched disorder. Unless the disorder is too strong, the phase diagram looks like the one without disorder, with a transition separating a fluid phase, where all variables have the same order of magnitude, and a condensed phase, where one variable is much larger than the others. We then show that the condensed phase exhibits various degrees of ‘intermediate symmetry breaking’: the site hosting the condensate is chosen neither uniformly at random, nor is it fixed by the disorder realization. Throughout the article, our heuristic arguments are complemented with direct Monte Carlo simulations.
Updated constraints on the cosmic string tension
International Nuclear Information System (INIS)
Battye, Richard; Moss, Adam
2010-01-01
We reexamine the constraints on the cosmic string tension from cosmic microwave background (CMB) and matter power spectra, and also from limits on a stochastic background of gravitational waves provided by pulsar timing. We discuss the different approaches to modeling string evolution and radiation. In particular, we show that the unconnected segment model can describe CMB spectra expected from thin string (Nambu) and field theory (Abelian-Higgs) simulations using the computed values for the correlation length, rms string velocity and small-scale structure relevant to each variety of simulation. Applying the computed spectra in a fit to CMB and SDSS data we find that Gμ/c 2 -7 (2σ) if the Nambu simulations are correct and Gμ/c 2 -7 in the Abelian-Higgs case. The degeneracy between Gμ/c 2 and the power spectrum slope n S is substantially reduced from previous work. Inclusion of constraints on the baryon density from big bang nucleosynthesis (BBN) imply that n S 2 and loop production size, α, we find that Gμ/c 2 -7 for αc 2 /(ΓGμ) 2 -11 /α for αc 2 /(ΓGμ)>>1.
Experimental constraint on quark electric dipole moments
Liu, Tianbo; Zhao, Zhiwen; Gao, Haiyan
2018-04-01
The electric dipole moments (EDMs) of nucleons are sensitive probes of additional C P violation sources beyond the standard model to account for the baryon number asymmetry of the universe. As a fundamental quantity of the nucleon structure, tensor charge is also a bridge that relates nucleon EDMs to quark EDMs. With a combination of nucleon EDM measurements and tensor charge extractions, we investigate the experimental constraint on quark EDMs, and its sensitivity to C P violation sources from new physics beyond the electroweak scale. We obtain the current limits on quark EDMs as 1.27 ×10-24 e .cm for the up quark and 1.17 ×10-24 e .cm for the down quark at the scale of 4 GeV2 . We also study the impact of future nucleon EDM and tensor charge measurements, and show that upcoming new experiments will improve the constraint on quark EDMs by about 3 orders of magnitude leading to a much more sensitive probe of new physics models.
Planck constraints on holographic dark energy
International Nuclear Information System (INIS)
Li, Miao; Zhang, Zhenhui; Li, Xiao-Dong; Ma, Yin-Zhe; Zhang, Xin
2013-01-01
We perform a detailed investigation on the cosmological constraints on the holographic dark energy (HDE) model by using the Plank data. We find that HDE can provide a good fit to the Plank high-l (l ∼> 40) temperature power spectrum, while the discrepancy at l ≅ 20-40 found in the ΛCDM model remains unsolved in the HDE model. The Plank data alone can lead to strong and reliable constraint on the HDE parameter c. At the 68% confidence level (CL), we obtain c = 0.508 ± 0.207 with Plank+WP+lensing, favoring the present phantom behavior of HDE at the more than 2σ CL. By combining Plank+WP with the external astrophysical data sets, i.e. the BAO measurements from 6dFGS+SDSS DR7(R)+BOSS DR9, the direct Hubble constant measurement result (H 0 = 73.8 ± 2.4 kms −1 Mpc −1 ) from the HST, the SNLS3 supernovae data set, and Union2.1 supernovae data set, we get the 68% CL constraint results c = 0.484 ± 0.070, 0.474 ± 0.049, 0.594 ± 0.051, and 0.642 ± 0.066, respectively. The constraints can be improved by 2%-15% if we further add the Plank lensing data into the analysis. Compared with the WMAP-9 results, the Plank results reduce the error by 30%-60%, and prefer a phantom-like HDE at higher significant level. We also investigate the tension between different data sets. We find no evident tension when we combine Plank data with BAO and HST. Especially, we find that the strong correlation between Ω m h 3 and dark energy parameters is helpful in relieving the tension between the Plank and HST measurements. The residual value of χ 2 Plank+WP+HST −χ 2 Plank+WP is 7.8 in the ΛCDM model, and is reduced to 1.0 or 0.3 if we switch the dark energy to w model or the holographic model. When we introduce supernovae data sets into the analysis, some tension appears. We find that the SNLS3 data set is in tension with all other data sets; for example, for the Plank+WP, WMAP-9 and BAO+HST, the corresponding Δχ 2 is equal to 6.4, 3.5 and 4.1, respectively. As a comparison
Adaptive laser link reconfiguration using constraint propagation
Crone, M. S.; Julich, P. M.; Cook, L. M.
1993-01-01
This paper describes Harris AI research performed on the Adaptive Link Reconfiguration (ALR) study for Rome Lab, and focuses on the application of constraint propagation to the problem of link reconfiguration for the proposed space based Strategic Defense System (SDS) Brilliant Pebbles (BP) communications system. According to the concept of operations at the time of the study, laser communications will exist between BP's and to ground entry points. Long-term links typical of RF transmission will not exist. This study addressed an initial implementation of BP's based on the Global Protection Against Limited Strikes (GPALS) SDI mission. The number of satellites and rings studied was representative of this problem. An orbital dynamics program was used to generate line-of-site data for the modeled architecture. This was input into a discrete event simulation implemented in the Harris developed COnstraint Propagation Expert System (COPES) Shell, developed initially on the Rome Lab BM/C3 study. Using a model of the network and several heuristics, the COPES shell was used to develop the Heuristic Adaptive Link Ordering (HALO) Algorithm to rank and order potential laser links according to probability of communication. A reduced set of links based on this ranking would then be used by a routing algorithm to select the next hop. This paper includes an overview of Constraint Propagation as an Artificial Intelligence technique and its embodiment in the COPES shell. It describes the design and implementation of both the simulation of the GPALS BP network and the HALO algorithm in COPES. This is described using a 59 Data Flow Diagram, State Transition Diagrams, and Structured English PDL. It describes a laser communications model and the heuristics involved in rank-ordering the potential communication links. The generation of simulation data is described along with its interface via COPES to the Harris developed View Net graphical tool for visual analysis of communications
On a Nonstationary Route Problem with Constraints
Directory of Open Access Journals (Sweden)
A. G. Chentsov
2012-01-01
Full Text Available The extremal route problem of permutations under constraints in the form of preceding conditions is investigated. It is supposed that an executer leaves the initial point (the base after which he visits a system of megalopolises (finite goal sets and performs some work on each megalopolis. The cost functions for executor permutations and interior works depend on the “visiting moment” that can correspond to the real time or can also correspond to the natural regular succession (the first visiting, the second visiting, and so on. An economic variant of the widely interpreted dynamic programming method (DPM is constructed. On this basis an optimal computer realized algorithm is constructed. A variant of a greed algorithm is proposed.
Identifying energy constraints to parasite resistance.
Allen, D E; Little, T J
2011-01-01
Life-history theory suggests that energetically expensive traits may trade off against each other, resulting in costs associated with the development or maintenance of a particular phenotype. The deployment of resistance mechanisms during parasite exposure is one such trait, and thus their potential benefit in fighting off parasites may be offset by costs to other fitness-related traits. In this study, we used trade-off theory as a basis to test whether stimulating an increased development rate in juvenile Daphnia would reveal energetic constraints to its ability to resist infection upon subsequent exposure to the castrating parasite, Pasteuria ramosa. We show that the presumably energetically expensive process of increased development rate does result in more infected hosts, suggesting that parasite resistance requires the allocation of resources from a limited source, and thus has the potential to be costly.
Constraints on the evolution of phenotypic plasticity
DEFF Research Database (Denmark)
Murren, Courtney J; Auld, Josh R.; Callahan, Hilary S
2015-01-01
Phenotypic plasticity is ubiquitous and generally regarded as a key mechanism for enabling organisms to survive in the face of environmental change. Because no organism is infinitely or ideally plastic, theory suggests that there must be limits (for example, the lack of ability to produce...... an optimal trait) to the evolution of phenotypic plasticity, or that plasticity may have inherent significant costs. Yet numerous experimental studies have not detected widespread costs. Explicitly differentiating plasticity costs from phenotype costs, we re-evaluate fundamental questions of the limits...... to the evolution of plasticity and of generalists vs specialists. We advocate for the view that relaxed selection and variable selection intensities are likely more important constraints to the evolution of plasticity than the costs of plasticity. Some forms of plasticity, such as learning, may be inherently...
A note on migration with borrowing constraints.
Ghatak, S; Levine, P
1994-12-01
"This note examines an important conflict between the theory and evidence on migration in LDCs. While the Harris-Todaro class of models explain the phenomenon of migration mainly by expected income differential between the economically advanced and the backward regions, the actual evidence in some cases suggests that migration could actually rise following a rise in income in backward areas. We resolve this puzzle by analysing migration in the context of the existence of imperfect credit markets in LDCs. We show that under certain plausible conditions, the rate of migration from the rural to the urban areas may actually rise when rural wages rise, as they ease the constraints on borrowing by potential migrants." excerpt
Constraint Embedding for Vehicle Suspension Dynamics
Directory of Open Access Journals (Sweden)
Jain Abhinandan
2016-06-01
Full Text Available The goal of this research is to achieve close to real-time dynamics performance for allowing auto-pilot in-the-loop testing of unmanned ground vehicles (UGV for urban as well as off-road scenarios. The overall vehicle dynamics performance is governed by the multibody dynamics model for the vehicle, the wheel/terrain interaction dynamics and the onboard control system. The topic of this paper is the development of computationally efficient and accurate dynamics model for ground vehicles with complex suspension dynamics. A challenge is that typical vehicle suspensions involve closed-chain loops which require expensive DAE integration techniques. In this paper, we illustrate the use the alternative constraint embedding technique to reduce the cost and improve the accuracy of the dynamics model for the vehicle.
Cosmological Constraints on Mirror Matter Parameters
International Nuclear Information System (INIS)
Wallemacq, Quentin; Ciarcelluti, Paolo
2014-01-01
Up-to-date estimates of the cosmological parameters are presented as a result of numerical simulations of cosmic microwave background and large scale structure, considering a flat Universe in which the dark matter is made entirely or partly of mirror matter, and the primordial perturbations are scalar adiabatic and in linear regime. A statistical analysis using the Markov Chain Monte Carlo method allows to obtain constraints of the cosmological parameters. As a result, we show that a Universe with pure mirror dark matter is statistically equivalent to the case of an admixture with cold dark matter. The upper limits for the ratio of the temperatures of ordinary and mirror sectors are around 0.3 for both the cosmological models, which show the presence of a dominant fraction of mirror matter, 0.06≲Ω_m_i_r_r_o_rh"2≲0.12.
Regional magnetic anomaly constraints on continental rifting
Vonfrese, R. R. B.; Hinze, W. J.; Olivier, R.; Bentley, C. R.
1985-01-01
Radially polarized MAGSAT anomalies of North and South America, Europe, Africa, India, Australia and Antarctica demonstrate remarkably detailed correlation of regional magnetic lithospheric sources across rifted margins when plotted on a reconstruction of Pangea. These major magnetic features apparently preserve their integrity until a superimposed metamorphoric event alters the magnitude and pattern of the anomalies. The longevity of continental scale magnetic anomalies contrasts markedly with that of regional gravity anomalies which tend to reflect predominantly isostatic adjustments associated with neo-tectonism. First observed as a result of NASA's magnetic satellite programs, these anomalies provide new and fundamental constraints on the geologic evolution and dynamics of the continents and oceans. Accordingly, satellite magnetic observations provide a further tool for investigating continental drift to compliment other lines of evidence in paleoclimatology, paleontology, paleomagnetism, and studies of the radiometric ages and geometric fit of the continents.
A new spin on causality constraints
Energy Technology Data Exchange (ETDEWEB)
Hartman, Thomas; Jain, Sachin; Kundu, Sandipan [Department of Physics, Cornell University, Ithaca, New York (United States)
2016-10-26
Causality in a shockwave state is related to the analytic properties of a four-point correlation function. Extending recent results for scalar probes, we show that this constrains the couplings of the stress tensor to light spinning operators in conformal field theory, and interpret these constraints in terms of the interaction with null energy. For spin-1 and spin-2 conserved currents in four dimensions, the resulting inequalities are a subset of the Hofman-Maldacena conditions for positive energy deposition. It is well known that energy conditions in holographic theories are related to causality on the gravity side; our results make a connection on the CFT side, and extend it to non-holographic theories.
Variables as Contextual Constraints in Translating Irony
Directory of Open Access Journals (Sweden)
Babîi Oana
2015-06-01
Full Text Available The translator’s role and responsibility are high in any act of interlingual communication, and even higher when irony, an indirect and deliberately elusive form of communication, is involved in the translation process. By allowing more than one possible interpretation, irony is inevitably exposed to the risk of being misunderstood. This paper attempts to capture the complexity of translating irony, making use of theoretical frameworks provided by literary studies and translation studies. It analyses if and how the types of irony, the literary genres and the cultural, normative factors, perceived as potential contextual constraints, have an impact on the translator’ choices in rendering irony in translation, taking illustrative examples from Jonathan Swift, Oscar Wilde, Aldous Huxley and David Lodge’s works.
Soft Budget Constraints in Public Hospitals.
Wright, Donald J
2016-05-01
A soft budget constraint arises when a government is unable to commit to not 'bailout' a public hospital if the public hospital exhausts its budget before the end of the budget period. It is shown that if the political costs of a 'bailout' are relatively small, then the public hospital exhausts the welfare-maximising budget before the end of the budget period and a 'bailout' occurs. In anticipation, the government offers a budget to the public hospital that may be greater than or less than the welfare-maximising budget. In either case, the public hospital treats 'too many' elective patients before the 'bailout' and 'too few' after. The introduction of a private hospital reduces the size of any 'bailout' and increases welfare. Copyright © 2015 John Wiley & Sons, Ltd.
Power System Operations With Water Constraints
Qiu, F.; Wang, J.
2015-12-01
The interdependency between water and energy, although known for many decades, has not received enough attention until recent events under extreme weather conditions (especially droughts). On one hand, water and several types of energy supplies have become increasingly scarce; the demand on water and energy continues to grow. On the other hand, the climate change has become more and more disruptive (i.e., intensity and frequency of extreme events), causing severe challenges to both systems simultaneously. Water and energy systems have become deeply coupled and challenges from extreme weather events must be addressed in a coordinated way across the two systems.In this work, we will build quantitative models to capture the interactions between water and energy systems. We will incorporate water constraints in power system operations and study the impact of water scarcity on power system resilience.
Hadronic EDM constraints on orbifold GUTs
International Nuclear Information System (INIS)
Hisano, Junji; Kakizaki, Mitsuru; Nagai, Minoru
2005-01-01
We point out that the null results of the hadronic electric dipole moment (EDM) searches constrain orbifold grand unified theories (GUTs), where the GUT symmetry and supersymmetry (SUSY) are both broken by boundary conditions in extra dimensions and it leads to rich fermion and sfermion flavor structures. A marginal chromoelectric dipole moment (CEDM) of the up quark is induced by the misalignment between the CP violating left- and right-handed up-type squark mixings, in contrast to the conventional four-dimensional SUSY GUTs. The up quark CEDM constraint is found to be as strong as those from charged lepton flavor violation (LFV) searches. The interplay between future EDM and LFV experiments will probe the structures of the GUTs and the SUSY breaking mediation mechanism
Evolution of Neutron Stars and Observational Constraints
Directory of Open Access Journals (Sweden)
Lattimer J.
2010-10-01
Full Text Available The structure and evolution of neutron stars is discussed with a view towards constraining the properties of high density matter through observations. The structure of neutron stars is illuminated through the use of several analytical solutions of Einstein’s equations which, together with the maximally compact equation of state, establish extreme limits for neutron stars and approximations for binding energies, moments of inertia and crustal properties as a function of compactness. The role of the nuclear symmetry energy is highlighted and constraints from laboratory experiments such as nuclear masses and heavy ion collisions are presented. Observed neutron star masses and radius limits from several techniques, such as thermal emissions, X-ray bursts, gammaray ﬂares, pulsar spins and glitches, spin-orbit coupling in binary pulsars, and neutron star cooling, are discussed. The lectures conclude with a discusson of proto-neutron stars and their neutrino signatures.
Implementing network constraints in the EMPS model
Energy Technology Data Exchange (ETDEWEB)
Helseth, Arild; Warland, Geir; Mo, Birger; Fosso, Olav B.
2010-02-15
This report concerns the coupling of detailed market and network models for long-term hydro-thermal scheduling. Currently, the EPF model (Samlast) is the only tool available for this task for actors in the Nordic market. A new prototype for solving the coupled market and network problem has been developed. The prototype is based on the EMPS model (Samkjoeringsmodellen). Results from the market model are distributed to a detailed network model, where a DC load flow detects if there are overloads on monitored lines or intersections. In case of overloads, network constraints are generated and added to the market problem. Theoretical and implementation details for the new prototype are elaborated in this report. The performance of the prototype is tested against the EPF model on a 20-area Nordic dataset. (Author)
Astrophysical constraints on Planck scale dissipative phenomena.
Liberati, Stefano; Maccione, Luca
2014-04-18
The emergence of a classical spacetime from any quantum gravity model is still a subtle and only partially understood issue. If indeed spacetime is arising as some sort of large scale condensate of more fundamental objects, then it is natural to expect that matter, being a collective excitation of the spacetime constituents, will present modified kinematics at sufficiently high energies. We consider here the phenomenology of the dissipative effects necessarily arising in such a picture. Adopting dissipative hydrodynamics as a general framework for the description of the energy exchange between collective excitations and the spacetime fundamental degrees of freedom, we discuss how rates of energy loss for elementary particles can be derived from dispersion relations and used to provide strong constraints on the base of current astrophysical observations of high-energy particles.
Universal constraints on axions from inflation
Energy Technology Data Exchange (ETDEWEB)
Ferreira, Ricardo Z.; Sloth, Martin S. [CP-Origins, Center for Cosmology and Particle Physics Phenomenology,University of Southern Denmark, Campusvej 55, 5230 Odense M (Denmark)
2014-12-19
We consider the presence of an axion like particle, σ, with a generic CP violating axial coupling of the form (α σ/f)FF-tilde, where F{sub μν} is the gauge field strength of a generic abelian U(1) gauge group, not necessarily associated with the standard electromagnetism, and f is the decay constant of the axion. It has previously been demonstrated that if the axion is identified with the inflaton, such an interaction can lead to measurable cosmological signatures (non-Gaussian modifications of the curvature perturbation spectrum) depending on the parameter ξ=α σ-dot /(fH). In the present paper we will show that the generation of curvature perturbation at horizon crossing due to the axial coupling has a universal form and remains unmodified in terms of the ξ parameter even if the axion, σ, is not identified with the inflaton. As a consequence, it does not appear to be possible to generate CMB tensor perturbations through this mechanism, larger than the vacuum ones, without violating the observational constraints unless we combine this mechanism with a curvaton or if the σ field becomes heavy and decays during inflation. Even in this last case there are non-trivial constraints coming from the slow-roll evolution of the curvature perturbation on super horizon scales which should be taken into account. We also comment on implications for inflationary models where axions play an important role as, for example, models of natural inflation where more than one axion are included and models where the curvaton is an axion.
Input and output constraints affecting irrigation development
Schramm, G.
1981-05-01
In many of the developing countries the expansion of irrigated agriculture is used as a major development tool for bringing about increases in agricultural output, rural economic growth and income distribution. Apart from constraints imposed by water availability, the major limitations considered to any acceleration of such programs are usually thought to be those of costs and financial resources. However, as is shown on the basis of empirical data drawn from Mexico, in reality the feasibility and effectiveness of such development programs is even more constrained by the lack of specialized physical and human factors on the input and market limitations on the output side. On the input side, the limited availability of complementary factors such as, for example, truly functioning credit systems for small-scale farmers or effective agricultural extension services impose long-term constraints on development. On the output side the limited availability, high risk, and relatively slow growth of markets for high-value crops sharply reduce the usually hoped-for and projected profitable crop mix that would warrant the frequently high costs of irrigation investments. Three conclusions are drawn: (1) Factors in limited supply have to be shadow-priced to reflect their high opportunity costs in alternative uses. (2) Re-allocation of financial resources from immediate construction of projects to longer-term increase in the supply of scarce, highly-trained manpower resources are necessary in order to optimize development over time. (3) Inclusion of high-value, high-income producing crops in the benefit-cost analysis of new projects is inappropriate if these crops could potentially be grown in already existing projects.
Origin of constraints in relativistic classical Hamiltonian dynamics
International Nuclear Information System (INIS)
Mallik, S.; Hugentobler, E.
1979-01-01
We investigate the null-plane or the front form of relativistic classical Hamiltonian dynamics as proposed by Dirac and developed by Leutwyler and Stern. For systems of two spinless particles we show that the algebra of Poincare generators is equivalent to describing dynamics in terms of two covariant constraint equations, the Poisson bracket of the two constraints being weakly zero. The latter condition is solved for certain simple forms of constraints
Evaluating Direct Manipulation Operations for Constraint-Based Layout
Zeidler , Clemens; Lutteroth , Christof; Stuerzlinger , Wolfgang; Weber , Gerald
2013-01-01
Part 11: Interface Layout and Data Entry; International audience; Layout managers are used to control the placement of widgets in graphical user interfaces (GUIs). Constraint-based layout managers are more powerful than other ones. However, they are also more complex and their layouts are prone to problems that usually require direct editing of constraints. Today, designers commonly use GUI builders to specify GUIs. The complexities of traditional approaches to constraint-based layouts pose c...
Financial constraints and international trade with endogenous mode of competition:
Bouët, Antoine; Vaubourg, Anne-Gaël
2015-01-01
The goal of this paper is to examine how financial constraints affect firms’ decisions to export when the mode of intra-sectoral competition is endogenous. We propose an extension of Neary and Tharakan’s (2012) model, in which firms resort to external funders to finance fixed export costs and investments in production capacities. We assume that sectors differ in financial constraint and that the cost of capital increases with the level of financial constraint. We first show that less financia...
Cosmic microwave background constraints on primordial black hole dark matter
Energy Technology Data Exchange (ETDEWEB)
Aloni, Daniel; Blum, Kfir [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Herzl 234, Rehovot (Israel); Flauger, Raphael, E-mail: daniel.aloni@weizmann.ac.il, E-mail: kfir.blum@weizmann.ac.il, E-mail: flauger@physics.ucsd.edu [University of California, 9500 Gilman Drive 0319, La Jolla, San Diego, CA, 92093 (United States)
2017-05-01
We revisit cosmic microwave background (CMB) constraints on primordial black hole dark matter. Spectral distortion limits from COBE/FIRAS do not impose a relevant constraint. Planck CMB anisotropy power spectra imply that primordial black holes with m {sub BH}∼> 5 M {sub ⊙} are disfavored. However, this is susceptible to sizeable uncertainties due to the treatment of the black hole accretion process. These constraints are weaker than those quoted in earlier literature for the same observables.
An Extensive Evaluation of Portfolio Approaches for Constraint Satisfaction Problems
Directory of Open Access Journals (Sweden)
Roberto Amadini
2016-06-01
Full Text Available In the context of Constraint Programming, a portfolio approach exploits the complementary strengths of a portfolio of different constraint solvers. The goal is to predict and run the best solver(s of the portfolio for solving a new, unseen problem. In this work we reproduce, simulate, and evaluate the performance of different portfolio approaches on extensive benchmarks of Constraint Satisfaction Problems. Empirical results clearly show the benefits of portfolio solvers in terms of both solved instances and solving time.
On relaxing the Mangasarian-Fromovitz constraint qualification
Czech Academy of Sciences Publication Activity Database
Kruger, A.Y.; Minchenko, L.; Outrata, Jiří
2014-01-01
Roč. 18, č. 1 (2014), s. 171-189 ISSN 1385-1292 R&D Projects: GA ČR GAP402/12/1309 Institutional support: RVO:67985556 Keywords : Nonlinear programming * Regularity conditions * Constraint qualifications * Lagrange multipliers * Mangasarian–Fromovitz constraint qualification * Constant rank constraint qualification Subject RIV: BA - General Mathematics Impact factor: 0.679, year: 2014 http://library.utia.cas.cz/separaty/2014/MTR/outrata-0426110.pdf
Financial constraint and R&D investment: evidence from CIS
Tiwari, A.K.; Mohnen, P.; Palm, F.C.; Schim van der Loeff, S.
2007-01-01
Using direct information on financial constraints from questionnaires, rather than the commonly used balance sheet information, this paper presents evidence that, controlling for traditional factors as size, market share, cooperative arrangement, and expected profitability, financial constraints affect a firm's decision of how much to invest in R&D activities. Apart from these constraints, other hampering factors as market uncertainty and institutional bottlenecks, regulations and organizatio...
Constraints and Logic Programming in Grammars and Language Analysis
DEFF Research Database (Denmark)
Christiansen, Henning
2014-01-01
Constraints are an important notion in grammars and language analysis, and constraint programming techniques have been developed concurrently for solving a variety of complex problems. In this chapter we consider the synthesis of these branches into practical and effective methods for language...... methods that combine constraints with logic grammars such as Definite Clause Grammars and CHR Grammars, and show also a direct relationship to abductive reasoning....
Energy Technology Data Exchange (ETDEWEB)
Malcles, J
2006-04-15
The analysis of B{sup {+-}} {yields} pi{sup {+-}}{pi}{sup 0} and B{sup {+-}} {yields} K{sup {+-}}{pi}{sup 0} modes has been done with a sample of 227 millions of B pairs corresponding to 205 fb{sup -1} of data collected between october 1999 and july 2004 with the BABAR detector. The branching ratios and CP asymmetries obtained are: Br({pi}{pi}{sup 0}) = (5.57 {+-} 0.60 {+-} 0.33)*10{sup -6}; Br(K{pi}{sup 0}) (11.50 {+-} 0.65 {+-} 0.57)*10{sup -6}; A({pi}{pi}{sup 0}) = (-0.007 {+-} 0.104 {+-} 0.023); and A(K{pi}{sup 0}) = (0.066 {+-} 0.055 {+-} 0.010). The constraints on the angle alpha of the unitarity triangle have been derived from the isospin analysis of B {yields} {pi}{pi} modes. The isospin symmetry has also been used to relate B {yields} K{pi} modes in order to constraint the CKM matrix. More significant constraints have been obtained with the SU(3) symmetry for B, Bs {yields} {pi}{pi}/ K{pi}/ KK modes. They are in good agreement with the Standard CKM fit. It has been shown that such an analysis will be competitive with the Standard CKM fit in the future and will allow to determine SU(3) breaking or New Physics parameters from data. (author)
Theory of constraints: A state-of-art review
Directory of Open Access Journals (Sweden)
Maryam Orouji
2015-11-01
Full Text Available The theory of constraints (TOC is a management tool, which considers any manageable system as being limited in reaching more of its objectives by some constraints. According to TOC, there is always, at least, one single constraint, and TOC implements a concentrating process to detect the constraint and restructure the remaining of the organization around it. This paper presents an overview of different perspectives of TOC and its implementation in different industries such as project management, quality management, outsourcing, product mix, make-to-buy, accounting, banking and health care, etc. The results indicate that the method has been extensively implemented in different areas of accounting.
Integral constraints on perturbations of Robertson-Walker cosmologies
International Nuclear Information System (INIS)
Ellis, G.F.R.; Jaklitsch, M.J.
1989-01-01
Integral constraints occur in the case of spherically symmetric inhomogeneities in Robertson-Walker universes, and (according to Traschen) in the case of general perturbations of these models. It is shown that these constraints are the same in the case of spherical symmetry, and they are interpreted as 'fitting conditions', that is, as constraints on the background Robertson-Walker model rather than on the nature of inhomogeneities. These integral constraints significantly affect the interpretation of anisotropies in the cosmic microwave background radiation. 22 refs
Block Pickard Models for Two-Dimensional Constraints
DEFF Research Database (Denmark)
Forchhammer, Søren; Justesen, Jørn
2009-01-01
In Pickard random fields (PRF), the probabilities of finite configurations and the entropy of the field can be calculated explicitly, but only very simple structures can be incorporated into such a field. Given two Markov chains describing a boundary, an algorithm is presented which determines...... for the domino tiling constraint represented by a quaternary alphabet. PRF models are also presented for higher order constraints, including the no isolated bits (n.i.b.) constraint, and a minimum distance 3 constraint by defining super symbols on blocks of binary symbols....
Parallel Execution of Multi Set Constraint Rewrite Rules
DEFF Research Database (Denmark)
Sulzmann, Martin; Lam, Edmund Soon Lee
2008-01-01
that the underlying constraint rewrite implementation executes rewrite steps in parallel on increasingly popular becoming multi-core architectures. We design and implement efficient algorithms which allow for the parallel execution of multi-set constraint rewrite rules. Our experiments show that we obtain some......Multi-set constraint rewriting allows for a highly parallel computational model and has been used in a multitude of application domains such as constraint solving, agent specification etc. Rewriting steps can be applied simultaneously as long as they do not interfere with each other.We wish...
Energy Technology Data Exchange (ETDEWEB)
Chen, Y.L.; Wang, G.Z., E-mail: gzwang@ecust.edu.cn; Xuan, F.Z.; Tu, S.T.
2015-04-15
Highlights: • Solution of constraint parameter τ* for through-wall cracked pipes has been obtained. • Constraint increases with increasing crack length and radius–thickness ratio of pipes. • Constraint-dependent LBB curve for through-wall cracked pipes has been constructed. • For increasing accuracy of LBB assessments, constraint effect should be considered. - Abstract: The leak-before-break (LBB) concept has been widely applied in the structural integrity assessments of pressured pipes in nuclear power plants. However, the crack-tip constraint effects in LBB analyses and designs cannot be incorporated. In this paper, by using three-dimensional finite element calculations, the modified load-independent T-stress constraint parameter τ* for circumferential through-wall cracked pipes with different geometries and crack sizes has been analyzed under different loading conditions, and the solutions of the crack-tip constraint parameter τ* have been obtained. Based on the τ* solutions and constraint-dependent J–R curves of a steel, the constraint-dependent LBB (leak-before-break) curves have been constructed. The results show that the constraint τ* increases with increasing crack length θ, mean radius R{sub m} and radius–thickness ratio R{sub m}/t of the pipes. In LBB analyses, the critical crack length calculated by the J–R curve of the standard high constraint specimen for pipes with shorter cracks is over-conservative, and the degree of conservatism increases with decreasing crack length θ, R{sub m} and R{sub m}/t. Therefore, the constraint-dependent LBB curves should be constructed to modify the over-conservatism and increase accuracy of LBB assessments.
Structure formation cosmic rays: Identifying observational constraints
Directory of Open Access Journals (Sweden)
Prodanović T.
2005-01-01
Full Text Available Shocks that arise from baryonic in-fall and merger events during the structure formation are believed to be a source of cosmic rays. These "structure formation cosmic rays" (SFCRs would essentially be primordial in composition, namely, mostly made of protons and alpha particles. However, very little is known about this population of cosmic rays. One way to test the level of its presence is to look at the products of hadronic reactions between SFCRs and the ISM. A perfect probe of these reactions would be Li. The rare isotope Li is produced only by cosmic rays, dominantly in αα → 6Li fusion reactions with the ISM helium. Consequently, this nuclide provides a unique diagnostic of the history of cosmic rays. Exactly because of this unique property is Li affected most by the presence of an additional cosmic ray population. In turn, this could have profound consequences for the Big-Bang nucleosynthesis: cosmic rays created during cosmic structure formation would lead to pre-Galactic Li production, which would act as a "contaminant" to the primordial 7Li content of metalpoor halo stars. Given the already existing problem of establishing the concordance between Li observed in halo stars and primordial 7Li as predicted by the WMAP, it is crucial to set limits to the level of this "contamination". However, the history of SFCRs is not very well known. Thus we propose a few model-independent ways of testing the SFCR species and their history, as well as the existing lithium problem: 1 we establish the connection between gamma-ray and Li production, which enables us to place constraints on the SFCR-made lithium by using the observed Extragalactic Gamma-Ray Background (EGRB; 2 we propose a new site for testing the primordial and SFCR-made lithium, namely, low-metalicity High-Velocity Clouds (HVCs, which retain the pre-Galactic composition without any significant depletion. Although using one method alone may not give us strong constraints, using them in