Results for "Sacha Welinski"

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High Resolution Optical Spectroscopy and Magnetic Properties of Yb3+ in Y2SiO5Jun 22 2016Rare earth doped crystals are promising systems for quantum information processing. In particular paramagnetic rare earths could be used to build coherent interfaces with optical and microwave photons. In addition, isotopes with non zero nuclear spins ... More
Simultaneous coherence enhancement of optical and microwave transitions in solid-state electronic spinsDec 22 2017Solid-state electronic spins are extensively studied in quantum information science, both for quantum computation, sensing and communication. Electronic spins are highly interesting due to their large magnetic moments, which offer fast operations for ... More
Electron Spin Coherences in Rare-Earth Optically Excited States for Microwave to Optical Quantum TransducersFeb 09 2018Efficient and reversible optical to microwave coherent transducers are required to enable entanglement transfer between superconducting qubits and light for quantum networks. Rare-earth-doped crystals that possess narrow optical and spin transitions are ... More
Modeling spontaneous breaking of time-translation symmetryOct 14 2014Mar 02 2015We show that an ultra-cold atomic cloud bouncing on an oscillating mirror can reveal spontaneous breaking of a discrete time translation symmetry. In many-body simulations we illustrate the process of the symmetry breaking that can be induced by atomic ... More
Regularized Gaussian Psychological Networks: Brief Report on the Performance of Extended BIC Model SelectionJun 18 2016In recent literature, the Gaussian Graphical model (GGM; Lauritzen, 1996), a network of partial correlation coefficients, has been used to capture potential dynamic relationships between psychological variables. The GGM can be estimated using regularization ... More
Non-resonant driving of H atom with broken time-reversal symmetryMay 15 2000The dynamics of atomic hydrogen placed in a static electric field and illuminated by elliptically polarized microwaves is studied in the range of small field amplitudes where perturbation calculations are applicable. For a general configuration of the ... More
Anderson localization and Mott insulator phase in the time domainFeb 09 2015Jun 16 2015Particles in space periodic potentials constitute standard models for investigation of crystalline phenomena in solid state physics. Time periodicity of periodically driven systems is a close analogue of space periodicity of solid state crystals. There ... More
N-conserving Bogoliubov vacuum of a two component Bose-Einstein condensate: Density fluctuations close to a phase separation conditionJan 10 2007Mar 26 2008Two-component Bose-Einstein condensates are considered within a number conserving version of the Bogoliubov theory. We show that the Bogoliubov vacuum state can be obtained in the particle representation in a simple form. We predict considerable density ... More
Classical threshold behaviour in a 1+1-dimensional model for double ionization in strong fieldsMay 23 2006Building on insights about the classical pathways to double ionization in strong laser fields we here propose a 1+1-dimensional model that captures essentials of the 3-d potential landscape and allows efficient studies of the process in reduced dimensions. ... More
N-particle Bogoliubov vacuum stateNov 23 2005We consider the Bogoliubov vacuum state in the number-conserving Bogoliubov theory proposed by Castin and Dum [Phys. Rev. A 57, 3008 (1998)]. We show that in the particle representation the vacuum can be written in a simple diagonal form. The vacuum state ... More
Images of a Bose-Einstein condensate: diagonal dynamical Bogoliubov vacuumMar 14 2005Evolution of a Bose-Einstein condensate subject to a time-dependent external perturbation can be described by a time-dependent Bogoliubov theory: a condensate initially in its ground state Bogoliubov vacuum evolves into a time-dependent excited state ... More
Neutrino masses in the R-parity violating MSSMMay 09 2000Nov 06 2000We compute one loop neutrino masses in the R-parity violating Minimal Supersymmetric Model, including the bilinear R-parity violating masses in the mass insertion approximation. To the order we calculate, our results are independent of the Higgs-lepton ... More
Breakdown of Anderson localization of interacting quantum bright solitons in a disorder potentialMay 15 2012Sep 06 2012The center of mass of a bright soliton in a Bose-Einstein condensate may reveal Anderson localization in the presence of a weak disorder potential. We analyze the effects of interactions between two bright solitons on the Anderson localization phenomenon. ... More
Wannier threshold law for two electron escape in the presence of an external electric fieldSep 27 2001We consider double ionization of atoms or ions by electron impact in the presence of a static electric field. As in Wanniers analysis of the analogous situation without external field the dynamics near threshold is dominated by a saddle. With a field ... More
Multielectron ionization of atoms in strong fields: Classical analysis in symmetric subspaceJun 07 2000We consider the final stage of multiple ionization of atoms in a strong linearly polarized laser field within a classical model. We propose that non-sequential multiple ionization is dominated by symmetric escape from a highly excited intermediate complex. ... More
Classical double ionization of atoms in strong fieldsMay 29 2000Recent high resolution measurements of the momenta of two electrons emitted from Argon atoms in a strong laser field show a strong preference for the outgoing electrons to have similar momenta and to be ejected in the same direction along the field. We ... More
QCD corrections to the charged Higgs decay of a heavy quarkJan 13 1993Jan 13 1993We present an analytic formula for the $O(\alpha_s)$ corrections to the decay $t\to H^+b$ for nonzero $m_H$ and $m_b$. The Equivalence Theorem is used to relate these corrections to those for the process $t\to W^+b$. Contrary to previously published results ... More
On the QCD corrections to the charged Higgs decay of a heavy quarkAug 21 1992Using dimensional regularization for both infrared and ultraviolet divergences, we confirm that the QCD corrections to the decay width $\Gamma(t\to H^+b)$ are equal to those to $\Gamma(t\to W^+b)$ in the limit of a large $t$ quark mass.
Protecting the Baryon Asymmetry in Theories with R-parity ViolationSep 26 1996We propose a mechanism for hiding the primordial baryon asymmetry from interactions that could wash it out. It requires the introduction of a baryon number carrying singlet which is in equilibrium in the early universe and shares any existing baryon asymmetry. ... More
Self-localization of a small number of Bose particles in a superfluid Fermi systemJun 11 2010Jun 23 2010We consider self-localization of a small number of Bose particles immersed in a large homogeneous superfluid mixture of fermions in three and one dimensional spaces. Bosons distort the density of surrounding fermions and create a potential well where ... More
Non standard neutrino interactions at LEP2 and the LHCOct 07 2011We consider Non-Standard neutrino Interactions (NSI) connecting two neutrinos with two first-generation fermions ($e, u$ or $d$), which we assume to arise at at dimension eight due to New Physics. The coefficient is normalised as $4 \epsilon G_F/\sqrt{2}$. ... More
Resonant dynamics of the H atom in an elliptically polarized microwave fieldNov 13 1998The dynamics of Rydberg states of atomic hydrogen driven by elliptically polarized microwaves of frequency fulfilling 2:1 classical resonance condition is investigated both semiclassically and quantum mechanically in a simplified two-dimensional model ... More
Self-localized impurities embedded in a one dimensional Bose-Einstein condensate and their quantum fluctuationsMar 17 2006We consider the self-localization of neutral impurity atoms in a Bose-Einstein condensate in a 1D model. Within the strong coupling approach, we show that the self-localized state exhibits parametric soliton behavior. The corresponding stationary states ... More
Classical analysis of correlated multiple ionization in strong fieldsNov 02 2000We discuss the final stages of the simultaneous ionization of two or more electrons due to a strong laser pulse. An analysis of the classical dynamics suggests that the dominant pathway for non-sequential escape has the electrons escaping in a symmetric ... More
Non-sequential triple ionization in strong fieldsJul 12 2001We consider the final stage of triple ionization of atoms in a strong linearly polarized laser field. We propose that for intensities below the saturation value for triple ionization the process is dominated by the simultaneous escape of three electrons ... More
Leptoquarks decaying to a top quark and a charged lepton at hadron collidersFeb 22 2011Mar 15 2011We study the sensitivity of the Tevatron and the 7 TeV LHC to a leptoquark S coupling to a top quark and a charged lepton L (= e, mu, or tau). For the Tevatron, we focus on the case m_S < m_t, where the leptoquark pair production cross section is large, ... More
Images of a Bose-Einstein condensate in position and momentum spaceDec 15 2005In the Bogoliubov theory a condensate initially prepared in its ground state described by stationary Bogoliubov vacuum and later perturbed by a time-dependent potential or interaction strength evolves into a time-dependent excited state which is dynamical ... More
Condensate Heating by Atomic LossesFeb 18 2003Atomic Bose-Einstein condensate is heated by atomic losses. Predicted depletion ranges from 1% for a uniform 3D condensate to around 10% for a quasi-1D condensate in a harmonic trap.
The Bogoliubov Theory of a BEC in Particle RepresentationOct 11 2002Jan 30 2003In the number-conserving Bogoliubov theory of BEC the Bogoliubov transformation between quasiparticles and particles is nonlinear. We invert this nonlinear transformation and give general expression for eigenstates of the Bogoliubov Hamiltonian in particle ... More
Greying of the Dark Soliton: Depletion in the Anomalous Mode of the Bogoliubov TheoryFeb 08 2002Oct 04 2002Quantum depletion from an atomic quasi one dimensional Bose-Einstein condensate with a dark soliton is studied in a framework of the Bogoliubov theory. Depletion is dominated by an anomalous mode localized in a notch of the condensate wave function. Depletion ... More
Condensate Phase MicroscopySep 06 2013Jan 29 2014We show that the phase of a Bose-Einstein condensate wave-function of ultra-cold atoms in an optical lattice potential in two-dimensions can be detected. The time-of-flight images, obtained in a free expansion of initially trapped atoms, are related to ... More
Proper phase imprinting method for a dark soliton excitation in a superfluid Fermi mixtureJun 26 2014Aug 07 2014It is common knowledge that a dark soliton can be excited in an ultra-cold atomic gas by means of the phase imprinting method. We show that, for a superfluid fermionic mixture, the standard phase imprinting procedure applied to both components fails to ... More
Basis independent neutrino masses in the $R_p$ violating MSSMOct 27 2000Mar 11 2001We calculate the neutrino mass matrix up to one loop order in the MSSM without R-parity, including the bilinears in the mass insertion approximation. This introduces additional diagrams usually neglected in the literature. We systematically consider the ... More
H atom in elliptically polarized microwaves: Semiclassical versus quantum resonant dynamicsSep 29 1998The dynamics of Rydberg states of atomic hydrogen illuminated by resonant elliptically polarized microwaves is investigated both semiclassically and quantum mechanically in a simplified two-dimensional model of an atom. Semiclassical predictions for quasienergies ... More
Is there a Vector Boson Coupling to Baryon Number?Nov 22 1994Discrepancies in measurements of the QCD running coupling constant are consistent with a new vector gauge boson coupling to baryon number with strength aB~0.1. Upsilon decays constrain such a boson to have a mass greater than about 35 GeV. It is difficult ... More
Boundary Dynamics of Three-Dimensional Asymptotically Anti-de Sitter Space-TimesJan 25 2016This thesis is organized as follows. In Chapter 2, some preliminaries are given on isometries and conformal symmetries, and we become familiar with the Virasoro algebra. Two examples of classical central charges are discussed. Chapter 3 contains an introduction ... More
Non-Standard Neutrino Interactions at CollidersAug 26 2011Many extensions of the Standard Model lead to non-standard neutrino interactions (NSI), which can affect the interpretation of current and future neutrino data. We explore an alternative approach to the study of these dimension eight four fermion interactions ... More
Solitons in coupled atomic-molecular Bose-Einstein condensates in a trapMay 16 2006Mar 26 2008We consider coupled atomic-molecular Bose-Einstein condensate system in a quasi-one-dimensional trap. In the vicinity of a Feshbach resonance the system can reveal soliton-like behavior. We analyze bright soliton solutions for the system in the trap and ... More
Pathways to non-sequential multiple ionization in strong laser fieldsMay 14 2003The outgoing electrons in non-sequential multiple ionization in intense laser fields are strongly correlated. The correlations can be explained within a classical model for interacting electrons in the presence of the external field. Here we extend the ... More
Two generalisations of the Binomial theoremDec 12 2005We prove two generalisations of the Binomial theorem that are also generalisations of the q-binomial theorem. These generalisations arise from the commutation relations satisfied by the components of the co-multiplications of non-simple root vectors in ... More
The Birman-Wenzl-Murakami algebra, Hecke algebra and representations of U_{q}(osp(1|2n))Jul 03 2006A representation of the Birman-Wenzl-Murakami algebra BW_{t}(-q^{2n},q) exists in the centraliser algebra End_{U_q(osp(1|2n))}(V^{\otimes t}), where V is the fundamental (2n+1)-dimensional irreducible U_{q}(osp(1|2n))-module. This representation is defined ... More
Changes of the topological charge of vorticesFeb 25 2002Dec 20 2002We consider changes of the topological charge of vortices in quantum mechanics by investigating analytical examples where the creation or annihilation of vortices occurs. In classical hydrodynamics of non-viscous fluids the Helmholtz-Kelvin theorem ensures ... More
Astrophysical Bounds on Milli-Charged Particles in Models with a ParaphotonOct 14 1993The upper bound on the number of relativistic species present at nucleosynthesis has been used to constrain particles with electric charge $\epsilon e$ ($10^{-8} < \epsilon <1$). We correct the bound previously calculated for milli-charged particles that ... More
LHC sensitivity to the decay of a Higgs boson to tau muNov 06 2012Nov 15 2012We study the sensitivity of the LHC, with 20 inverse-fb of data, to lepton flavour violating Higgs boson decays h -> tau+ mu- (and h -> tau+ e-). We consider the large population of Higgses produced in gluon fusion, combined with leptonic decays of the ... More
Soliton in BCS superfluid Fermi gasJul 22 2004We analyze a superfluid state of two species gas of fermions trapped in a quasi-1D harmonic potential and interacting via attractive s-wave collisions. It is shown that the gap equation posesses a self consistent solution with an antisymmetric gap function. ... More
Bileptons: Present Limits and Future ProspectsSep 26 1996We define bileptons to be bosons coupling to a pair of leptons and construct the most general dimension four lagrangian involving scalar and vector bileptons. We concentrate on fields with lepton number 2, and derive model independent bounds on their ... More
Simulation of frustrated classical XY models with ultra-cold atoms in 3D triangular optical latticesNov 21 2012Jan 25 2013Miscellaneous magnetic systems are being recently intensively investigated because of their potential applications in modern technologies. Nonetheless, a many body dynamical description of complex magnetic systems may be cumbersome, especially when the ... More
Artificial magnetic field induced by an evanescent waveSep 10 2013Jan 14 2015Cold atomic gases are perfect laboratories for realization of quantum simulators. In order to simulate solid state systems in the presence of magnetic fields special effort has to be made because atoms are charge neutral. There are different methods for ... More
Rotating Drops of Axion Dark MatterMar 14 2016We consider how QCD axions produced by the misalignment mechanism could form galactic dark matter halos. We recall that stationary, gravitationally stable axion field configurations have the size of an asteroid with masses of order $10^{-13} $ solar masses ... More
Lieb-Liniger model: emergence of dark solitons in the course of measurements of particle positionsMay 25 2015Sep 04 2015Lieb-Liniger model describes bosons with contact interactions in one-dimensional space. In the limit of weak repulsive particle interactions, there are two types of low lying excitation spectrum. The first is reproduced by the Bogoliubov dispersion relation, ... More
Anderson localization in the time domainMar 18 2016Aug 18 2016In analogy with usual Anderson localization taking place in time-independent disordered quantum systems where the disorder acts in configuration space, systems exposed to temporally disordered potentials can display Anderson localization in the time domain. ... More
Inert-states of spin-5 and spin-6 Bose-Einstein condensatesAug 30 2011In this paper we consider spinor Bose-Einstein condensates with spin f=5 and f=6 in the presence and absence of external magnetic field at the mean field level. We calculate all of so-called inert-states of these systems. Inert-states are very unique ... More
Matter-wave analog of an optical random laserMar 17 2011Jul 20 2011The accumulation of atoms in the lowest energy level of a trap and the subsequent out-coupling of these atoms is a realization of a matter-wave analog of a conventional optical laser. Optical random lasers require materials that provide optical gain but, ... More
Pathways to double ionization of atoms in strong fieldsOct 12 2000Jan 31 2001We discuss the final stages of double ionization of atoms in a strong linearly polarized laser field within a classical model. We propose that all trajectories leading to non-sequential double ionization pass close to a saddle in phase space which we ... More
Quantum Superalgebras at Roots of Unity and Topological Invariants of Three-manifoldsJan 09 2006The general method of Reshetikhin and Turaev is followed to develop topological invariants of closed, connected, orientable 3-manifolds from a new class of algebras called pseudo-modular Hopf algebras. Pseudo-modular Hopf algebras are a class of Z_2-graded ... More
On Stellar Dynamo Processes and Differential RotationFeb 28 2003Many stars exhibit strong magnetic fields, some of which are thought to be of primordial origin and others a sign of magnetic dynamo processes. We briefly review the results of observational studies of solar-type stars seeking to evaluate the linkage ... More
Simulation of non-Abelian lattice gauge fields with a single component gasMar 05 2014Jul 14 2014We show that non-Abelian lattice gauge fields can be simulated with a single component ultra-cold atomic gas in an optical lattice potential. An optical lattice can be viewed as a Bravais lattice with a $N$-point basis. An atom located at different points ... More
Many-body Matter-wave Dark SolitonJul 26 2013Dec 17 2013The Gross-Pitaevskii equation - which describes interacting bosons in the mean-field approximation - possesses solitonic solutions in dimension one. For repulsively interacting particles, the stationary soliton is dark, i.e. is represented by a local ... More
Driven Rydberg atoms reveal quartic level repulsionJan 17 2001The dynamics of Rydberg states of a hydrogen atom subject simultaneously to uniform static electric field and two microwave fields with commensurate frequencies is considered in the range of small fields amplitudes. In the certain range of the parameters ... More
On the $U_{q}(osp(1|2n))$ and $U_{-q}(so(2n+1))$ Uncoloured Quantum Link InvariantsJan 21 2009Let $L$ be a link and $\Phi^{A}_{L}(q)$ its link invariant associated with the vector representation of the quantum (super)algebra $U_{q}(A)$. Let $F_{L}(r,s)$ be the Kauffman link invariant for $L$ associated with the Birman--Wenzl--Murakami algebra ... More
A Tutorial on Regularized Partial Correlation NetworksJul 05 2016Oct 03 2016Recent years have seen an emergence of network modeling applied to moods, attitudes, and problems in the realm of psychology. In this framework, psychological variables are understood to directly interact with each other rather than being caused by an ... More
Rigorous Analysis of Singularities and Absence of Analytic Continuation at First Order Phase Transition Points in Lattice Spin ModelsMay 20 2003We report about two new rigorous results on the non-analytic properties of thermodynamic potentials at first order phase transition. The first one is valid for lattice models ($d\geq 2$) with arbitrary finite state space, and finite-range interactions ... More
Exploratory graph analysis: a new approach for estimating the number of dimensions in psychological researchMay 07 2016Oct 19 2016The estimation of the correct number of dimensions is a long-standing problem in psychometrics. Several methods have been proposed, such as parallel analysis (PA), Kaiser-Guttman's eigenvalue-greaterthan-one rule, multiple average partial procedure (MAP), ... More
Influence of the learning method in the performance of feedforward neural networks when the activity of neurons is modifiedApr 21 2014A method that allows us to give a different treatment to any neuron inside feedforward neural networks is presented. The algorithm has been implemented with two very different learning methods: a standard Back-propagation (BP) procedure and an evolutionary ... More
Turbulent Convection Under the Influence of Rotation: Sustaining a Strong Differential RotationJun 12 2002The intense turbulence present in the solar convection zone is a major challenge to both theory and simulation as one tries to understand the origins of the striking differential rotation profile with radius and latitude that has been revealed by helioseismology. ... More
Hunting for giant cells in deep stellar convective zones using wavelet analysisJan 06 2011We study the influence of stratification on stellar turbulent convection near the stellar surface and in depth by carrying out 3D high resolution hydrodynamic simulations with the ASH code. Four simulations with different radial density contrast corresponding ... More
Basis-independent methods for the two-Higgs-doublet modelApr 06 2005Nov 27 2005In the most general two-Higgs-doublet model (2HDM), unitary transformations between the two Higgs fields do not change the functional form of the Lagrangian. All physical observables of the model must therefore be independent of such transformations (i.e., ... More
Solar Turbulence and Magnetism Studied Within a Rotating Convective Spherical ShellFeb 28 2003We discuss recent advances made in modelling the complex magnetohydrodynamics of the Sun using our anelastic spherical harmonics (ASH) code. We have conducted extensive 3--D simulations of compressible convection in rotating spherical shells with and ... More
NGC 346: Looking in the Cradle of a Massive Star ClusterNov 02 2015[abridged] How does a star cluster of more than few 10,000 solar masses form? We present the case of the cluster NGC 346 in the Small Magellanic Cloud, and its star-forming region N66, and we propose a scenario for its formation, based on observations ... More
Three dimensional non-linear evolution of a magnetic flux tube in a spherical shell: Influence of turbulent convection and associated mean flowsJul 13 2009We present the first 3D MHD study in spherical geometry of the non-linear dynamical evolution of magnetic flux tubes in a turbulent rotating convection zone. We study numerically the rise of magnetic toroidal flux ropes from the base of a modelled convection ... More
Estimating Psychological Networks and their Accuracy: A Tutorial PaperApr 28 2016Sep 14 2016The usage of psychological networks that conceptualize psychological behavior as a complex interplay of psychological and other components has gained increasing popularity in various fields of psychology. While prior publications have tackled the topics ... More
LHC sensitivity to lepton flavour violating Z boson decaysJul 20 2012Aug 30 2012We estimate that the LHC could set bounds BR(Z -> mu^\pm e^\mp) < 4.1 * 10^{-7} and BR(Z -> tau^\pm mu^\mp)< 3.5 * 10^{-6} (at 95% C.L.) with 20 inverse fb of data at 8 TeV. A similar sensitivity can be anticipated for Z -> tau^\pm e^\mp, because we consider ... More
Comment on "Quantum entangled dark solitons formed by ultracold atoms in optical lattices"Jan 07 2010We demonstrate that knowledge of two body correlation functions like g2(x) is insufficient to draw conclusions about whether solitons fill in or not in individual experimental runs. In our example, g2 is filled in, while the soliton is not.
Images of the Dark Soliton in a Depleted CondensateDec 19 2002Feb 07 2003The dark soliton created in a Bose-Einstein condensate becomes grey in course of time evolution because its notch fills up with depleted atoms. This is the result of quantum mechanical calculations which describes output of many experimental repetitions ... More
Simulations of core convection and resulting dynamo action in rotating A-type starsSep 28 2004We present the results of 3--D nonlinear simulations of magnetic dynamo action by core convection within A-type stars of 2 solar masses, at a range of rotation rates. We consider the inner 30% by radius of such stars, with the spherical domain thereby ... More
Simulations of core convection in rotating A-type stars: Differential rotation and overshootingSep 30 2003We present the results of 3--D simulations of core convection within A-type stars of 2 solar masses, at a range of rotation rates. We consider the inner 30% by radius of such stars, thereby encompassing the convective core and some of the surrounding ... More
LeptogenesisFeb 20 2008Jun 06 2008Leptogenesis is a class of scenarios where the baryon asymmetry of the Universe is produced from a lepton asymmetry generated in the decays of a heavy sterile neutrino. We explain the motivation for leptogenesis. We review the basic mechanism, and describe ... More
The smallest neutrino massNov 30 2006Jan 17 2007We consider models where one Majorana neutrino is massless at tree level (like the see saw with two right-handed neutrinos), and compute the contribution to its mass m generated by two-loop quantum corrections. The result is m \sim 10^{-13}eV in the SM ... More
Baryogenesis at Low Reheating TemperaturesJan 28 2000Mar 18 2000We note that the maximum temperature during reheating can be much greater than the reheating temperature $T_r$ at which the Universe becomes radiation dominated. We show that the Standard Model anomalous $(B+L)$-violating processes can therefore be in ... More
Collective excitation of trapped degenerate Fermi gasesNov 13 2001Mar 21 2002We show that the slow driving of a focused laser beam through the cloud of trapped cold fermions allows for a creation of the collective excitation in the system. The method, proposed originally by us for bosons, seems to be quite feasible experimentally ... More
Dark soliton in a disorder potentialNov 22 2011Feb 09 2012We consider dark soliton in a Bose-Einstein condensate in the presence of a weak disorder potential. Deformation of the soliton shape is analyzed within the Bogoliubov approach and by employing expansion in eigenstates of the P\"oschl-Teller Hamiltonian. ... More
Theoretical seismology in 3D : nonlinear simulations of internal gravity waves in solar-like starsMar 17 2014Apr 04 2014Internal gravity waves (hereafter IGWs) are studied for their impact on the angular momentum transport in stellar radiation zones and the information they provide about the structure and dynamics of deep stellar interiors. We here present the first 3D ... More
Quantum Depletion of an Excited CondensateOct 03 2001Oct 07 2002We analyze greying of the dark soliton in a Bose-Einstein condensate in the limit of weak interaction between atoms. The condensate initially prepared in the excited dark soliton state is loosing atoms because of spontaneous quantum depletion. These atoms ... More
On Preserving a B+L Asymmetry Produced in the Early UniverseMar 09 1994One of the most efficient mechanisms for producing the baryon asymmetry of the Universe is the decay of scalar condensates in a SUSY GUT as was first suggested by Affleck and Dine. We show that given a large enough asymmetry, the baryon number will be ... More
Assimilating data into an αω dynamo model of the sun: A variational approachMay 03 2011We have developed a variational data assimilation technique for the Sun using a toy {\alpha}{\Omega} dynamo model. The purpose of this work is to apply modern data assimilation techniques to solar data using a physically based model. This work represents ... More
Dark Matter Abundance and Electroweak Baryogenesis in the CMSSMJul 15 1999The Minimal Supersymmetric Standard Model has a candidate dark matter particle in its spectrum and may be able to generate the baryon asymmetry of the Universe (BAU) at the electroweak phase transition. In the Constrained MSSM, we find the area of parameter ... More
Model independent constraints on leptoquarks from rare processesSep 22 1993We present model independent constraints on the masses and couplings to fermions of $B$ and $L$ conserving leptoquarks. Such vector or scalar particles could have masses below 100 GeV and be produced at HERA; we list the generation dependent bounds that ... More
Updated Bounds on Milli-Charged ParticlesJan 18 2000May 02 2000We update the bounds on fermions with electric charge $\epsilon e$ and mass $m_\epsilon$. For $m_\epsilon\lsim m_e$ we find $10^{-15}\lsim\epsilon<1$ is excluded by laboratory experiments, astrophysics and cosmology. For larger masses, the limits are ... More
Solving the flavour problem with hierarchical fermion wave functionsNov 21 2007Apr 03 2008We investigate the flavour structure of generic extensions of the SM where quark and lepton mass hierarchies and the suppression of flavour-changing transitions originate only by the normalization constants of the fermion kinetic terms. We show that in ... More
Looking Deep Within an A-type Star: Core Convection Under the Influence of RotationFeb 28 2003The advent of massively parallel supercomputing has begun to permit explicit 3--D simulations of turbulent convection occurring within the cores of early-type main sequence stars. Such studies should complement the stellar structure and evolution efforts ... More
Detecting patterns of species diversification in the presence of both rate shifts and mass extinctionsApr 22 2014Aug 31 2015Recent methodological advances are enabling better examination of speciation and extinction processes and patterns. A major open question is the origin of large discrepancies in species number between groups of the same age. Existing frameworks to model ... More
Massive stars reveal variations of the stellar initial mass function in the Milky Way stellar clustersMay 26 2016Sep 27 2016We investigate whether the stellar initial mass function (IMF) is universal, or whether it varies significantly among young stellar clusters in the Milky Way. We propose a method to uncover the range of variation of the parameters that describe the shape ... More
Experimental violation of a d-dimensional Bell inequality using energy-time entangled photonsSep 17 2014Feb 06 2015We experimentally study the violation of the CGLMP inequality for entangled 2-qubit and 2-qutrit states with different degrees of entanglement using numerically optimized measurement settings. The qudits are encoded and manipulated in the frequency spectrum ... More
Chaotic Rydberg atoms with broken time-reversal symmetrySep 01 1999The dynamics of Rydberg states of atomic hydrogen perturbed simultaneously by a static electric field and a resonant microwave field of elliptical polarization is analysed in the quantum perturbative limit of small amplitudes. For some configurations, ... More
From transition magnetic moments to majorana neutrino massesJun 08 2005Oct 12 2005It is well known that a majorana mass induces a (small) transition magnetic moment. The converse is also true; in this paper we estimate the loop contribution of transition magnetic moments $[\mu]_{\alpha \beta}$ to the neutrino mass matrix $[m]_{\alpha ... More
Of Contact Interactions and CollidersOct 17 2014The hierarchy of scales which would allow dimension-six contact interactions to parametrise New Physics may not be verified at colliders. Instead, we explore the feasability and usefulness of parametrising the high-energy tail of distributions at the ... More
Huge quantum particle number fluctuations in a two-component Bose gas in a double-well potentialApr 09 2010May 24 2011Two component Bose gas in a double well potential with repulsive interactions may undergo a phase separation transition if the inter-species interactions outweigh the intra-species ones. We analyze the transition in the strong interaction limit within ... More
Mean field loops versus quantum anti-crossing nets in trapped Bose-Einstein condensatesAug 31 2001Oct 30 2002We study a Bose-Einstein condensate trapped in an asymmetric double well potential. Solutions of the time-independent Gross-Pitaevskii equation reveal intrinsic loops in the energy (or chemical potential) level behavior when the shape of the potential ... More
Quantum bright soliton in a disorder potentialNov 04 2009At very low temperature, a quasi-one-dimensional ensemble of atoms with attractive interactions tend to form a bright soliton. When exposed to a sufficiently weak external potential, the shape of the soliton is not modified, but its external motion is ... More
Stirring Bose-Einstein condensateMay 23 2002Sep 18 2002By shining a tightly focused laser light on the condensate and moving the center of the beam along the spiral line one may stir the condensate and create vortices. It is shown that one can induce rotation of the condensate in the direction opposite to ... More