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
Coherent spin dynamics of ytterbium ions in yttrium orthosilicateDec 01 2017We investigate the electron and nuclear spin coherence properties of ytterbium ($\mathrm{Yb}^{3+}$) ions with non-zero nuclear spin, within an yttrium orthosilicate (Y$_2$SiO$_5$) crystal, with a view to their potential application in quantum memories ... More
Simultaneous coherence enhancement of optical and microwave transitions in solid-state electronic spinsDec 22 2017Jul 27 2018Solid-state electronic spins are extensively studied in quantum information science, as their large magnetic moments offer fast operations for computing and communication, and high sensitivity for sensing. However, electronic spins are more sensitive ... More
Spectroscopic study of hyperfine properties in $^{171}$Yb$^{3+}$:Y$_2$SiO$_5$Dec 22 2017Nov 08 2018Rare-earth ion doped crystals are promising systems for quantum communication and quantum information processing. In particular, paramagnetic rare-earth centres can be utilized to realize quantum coherent interfaces simultaneously for optical and microwave ... 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
The Pressure of Misalignment Axions: a Difference from WIMPs in Galaxy Formation?Oct 18 2014Two populations of axions can contribute to cold dark matter: the classical field produced via the misalignment mechanism, and the modes produced in the decay of strings. The classical field has extra pressure, as compared to WIMPs, which could have observable ... More
Interpretations of the NuTeV $\sin^2 θ_W$Sep 26 2002Nov 03 2002We summarize theoretical explanations of the three $\sigma$ discrepancy between $\sin^2 \theta_W$ measured by NuTeV and predicted by the Standard Model global fit. Possible new physics explanations ({\it e.g.} an unmized $Z'$) are not compelling. The ... 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
Mu to e gamma and matching at mWJan 26 2016Jul 02 2016Several experiments search for \mu - e flavour change, for instance in \mu ->e conversion, \mu-> e \gamma, and \mu -> 3e. This paper studies how to translate these experimental constraints from low energy to a New Physics scale M >> mW. A basis of QCD ... 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
Weak-scale implications of thermal leptogenesis in SUSYApr 12 2003Feb 14 2004Thermal leptogenesis is an attractive mechanism for generating the baryon asymmetry of the Universe. However, in supersymmetric models, the parameter space is severely restricted by the gravitino bound on the reheat temperature $T_{RH}$. Using a parametrisation ... More
From weak-scale observables to leptogenesisFeb 11 2003Feb 20 2003Thermal leptogenesis is an attractive mechanism for generating the baryon asymmetry of the Universe. However, in supersymmetric models, the parameter space is severely restricted by the gravitino bound on the reheat temperature $T_{RH}$. For hierarchical ... More
Ingredients and Equations for Making a Magnetic Field in the Early UniverseMay 15 1996The ingredients required to create a magnetic field in the early Universe are identified, and compared with Sakharov's conditions for baryogenesis. It is also shown that a long range coherent magnetic field is not generated by the classical rolling Higgs ... 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
Including the Z in an Effective Field Theory for dark matter at the LHCMar 20 2014Oct 18 2014An Effective Field Theory for dark matter at a TeV-scale hadron collider should include contact interactions of dark matter with the partons, the Higgs and the Z. This note estimates the impact of including dark matter-Z interactions on the complementarity ... More
Flavoured LeptogenesisMay 11 2007May 18 2007Thermal leptogenesis, in the seesaw model, is a popular mechanism for generating the Baryon Asymmetry of the Universe. It was noticed recently, that including lepton flavour can modify significantly the results. These proceedings aim to discuss why and ... 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
Mu to e gamma in the 2 Higgs Doublet Model: an exercise in EFTJan 08 2016Apr 26 2016The 2 Higgs Doublet Model (2HDM) of type III has renormalisable Lepton Flavour-Violating couplings, and its one and two-loop ("Barr-Zee") contributions to $\mu \to e \gamma$ are known. In the decoupling limit, where the mass scale M of the second doublet ... More
Axions: Bose Einstein Condensate or Classical Field?May 06 2014Dec 20 2014The axion is a motivated dark matter candidate, so it would be interesting to find features in Large Scale Structures specific to axion dark matter. Such features were proposed for a Bose Einstein condensate of axions, leading to confusion in the literature ... More
Learning about flavour structure from tau to ell gamma and mu to e gamma?Dec 13 2011Feb 06 2012Current and upcoming experiments should improve the sensitivity to radiative lepton decays by an order of magnitude. This paper assumes that one of the tau --> (e, mu) gamma decays is observed, and explores the structure and consequences of the required ... More
Cosmological Constraints on B-L ViolationAug 26 1998This is a review of the cosmological bounds on $B-L$ violating interactions, and the loopholes in the argument that gives these constraints. If one assumes that the baryon asymmetry we observe today was present above the electroweak phase transition in ... More
Parametrizations of the Seesaw, or, can the Seesaw be tested?Sep 29 2004This proceedings contains a review, followed by a more speculative discussion. I review different coordinate choices on the 21-dimensional parameter space of the seesaw, and which of these 21 quantities are observable. In MSUGRA, there is a 1-1 correspondance ... More
Basis independent parametrisations of R parity violation in the soft SUSY breaking sectorAug 26 1998The magnitude of R-parity violating coupling constants depends on which direction in the space of weak doublets with hypercharge = -2 corresponds to the Higgs. To address this ``basis dependence'', one can construct combinations of coupling constants ... More
Divided power algebras over an operadDec 11 2017Nov 26 2018The purpose of this paper is to give a characterisation of divided power algebras over a reduced operad. Such a characterisation is given in terms of polynomial operations, following the classical example of divided power algebras. We describe these polynomial ... More
Electron Spin Coherences in Rare-Earth Optically Excited States for Microwave to Optical Quantum TransducersFeb 09 2018Feb 16 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
High-cooperativity coupling of a rare-earth spin ensemble to a superconducting resonator using yttrium orthosilicate as a substrateJan 10 2019Apr 25 2019Yttrium orthosilicate (Y$_2$SiO$_5$, or YSO) has proved to be a convenient host for rare-earth ions used in demonstrations of microwave quantum memories and optical memories with microwave interfaces, and shows promise for coherent microwave--optical ... More
High-cooperativity coupling of rare-earth spins using yttrium orthosilicate as a substrateJan 10 2019Yttrium orthosilicate (Y$_2$SiO$_5$, or YSO) has proved to be a convenient host for rare-earth ions used in demonstrations of microwave quantum memories and optical memories with microwave interfaces, and shows promise for coherent microwave-optical conversion ... 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
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
A lower bound on the right-handed neutrino mass from leptogenesisFeb 25 2002Apr 23 2002In the seesaw model, the baryon asymmetry of the Universe can be generated by the decay of the lightest right-handed neutrino, nu_R. For a hierarchical spectrum of right-handed neutrinos, we show that there is a model independent upper bound on the CP ... More
Determining See-Saw Parameters from Weak Scale Measurements?Apr 08 2001Sep 18 2001The see-saw mechanism is a very attractive explanation for small neutrino masses, parametrized at the GUT scale by the right-handed Majorana mass matrix, ${\cal M}$, and the neutrino Yukawa matrix, ${\bf Y_\nu}$. We show that in a SUSY model with universal ... 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
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
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
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
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
Quantum measurements of timeOct 30 2018We propose a time-of-arrival operator in quantum mechanics by conditioning on a quantum clock. This allows us to bypass the problems that afflict previous proposals, and to obtain a Hermitian time of arrival operator whose probability distribution arises ... 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
Various definitions of Minimal Flavour Violation for LeptonsJul 29 2006Neutrino masses imply the violation of lepton flavour and new physics beyond the Standard Model. However, flavour change has only been observed in oscillations. In analogy with the quark sector, we could deduce the existence of a principle of Minimal ... 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
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
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
Reconstructing SeesawsAug 02 2011Nov 03 2011We explore some aspects of "reconstructing" the heavy singlet sector of supersymmetric type I seesaw models, for two, three or four singlets. We work in the limit where one light neutrino is massless. In an ideal world, where selected coefficients of ... More
Leptogenesis and low-energy phasesJun 28 2002Oct 09 2002In supersymmetric models, the CP asymmetry produced in the decay of the lightest right-handed neutrino, $\equiv epsilon$, can be written as a function of weak scale parameters. We introduce a way of separating epsilon into contributions from the various ... More
Thermalisation after inflationSep 07 2000Nov 06 2000During (re)heating of the universe after inflation, the relativistic decay products of the inflaton field $\phi$ must lose energy and additional particles must be produced to attain a thermalised state at a temperature $T_{\reh}$. We estimate the rate ... 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
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
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
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
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
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
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
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
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
Constraints on 2l2q operators from $μ- e$ flavour-changing meson decaysJul 26 2018Nov 19 2018We study lepton flavour violating two- and three-body decays of pseudoscalar mesons in Effective Field Theory (EFT). We give analytic formulae for the decay rates in the presence of a complete basis of QED and QCD-invariant operators. The constraints ... More
Estimated constraints on t-channel Leptoquark exchange from LHC contact interaction searchesSep 08 2014The t-channel exchange of a first generation leptoquark could contribute to the cross-section for q q-bar to e+e-. The leptoquark is off-shell, so this process can be sensitive to leptoquarks beyond the mass reach of pair production searches at the LHC ... More
Bose Einstein condensation of the classical axion field in cosmology?Jul 30 2013Dec 04 2013The axion is a motivated cold dark matter candidate, which it would be interesting to distinguish from weakly interacting massive particles. Sikivie has suggested that axions could behave differently during non-linear galaxy evolution, if they form a ... More
Similar Dark Matter and Baryon abundances with TeV-scale LeptogenesisAug 02 2012Aug 10 2012We estimate the Baryon Asymmetry of the Universe (BAU) produced in an inverse seesaw model containing extra light singlets, and with lepton number conservation prior to the electroweak phase transition. An order one CP asymmetry epsilon is required to ... More
Constraints on two-lepton, two quark operatorsAug 02 2010Aug 15 2010Physics from beyond the Standard Model, such as leptoquarks, can induce four fermion operators involving a quark, an anti-quark, a lepton and an anti-lepton. We update the (flavour dependent) constraints on the coefficients of such interactions, arising ... More
Leptogenesis and a Jarlskog InvariantDec 01 2003Dec 10 2003The relation between low energy CP violating phases, and the CP asymmetry of leptogenesis, $\epsilon$, is investigated. Although it is known that in general those are independent, there may be a relation when a model is specified. We construct a Jarlskog ... More
Quantum measurements of timeOct 30 2018Mar 27 2019We propose a time-of-arrival operator in quantum mechanics by conditioning on a quantum clock. This allows us to bypass the problems that afflict previous proposals, and to obtain a Hermitian time of arrival operator whose probability distribution arises ... 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
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
Quantum dark solitons in Bose gas confined in a hard wall boxMay 26 2017Sep 16 2017Schr\"odinger equation for Bose gas with repulsive contact interactions in one-dimensional space may be solved analytically with the help of the Bethe ansatz if we impose periodic boundary conditions. It was shown that in such a system there exist many-body ... 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
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
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
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.
Anderson localization of a Rydberg electron along a classical orbitMar 24 2017May 12 2017Anderson localization is related to exponential localization of a particle in the configuration space in the presence of a disorder potential. Anderson localization can be also observed in the momentum space and corresponds to quantum suppression of classical ... More
Fractional Time CrystalsDec 28 2018Mar 14 2019Time crystals are quantum systems which are able to reveal condensed matter behavior in the time domain. It is known that crystalization in time can be observed in a periodically driven many-body system when interactions between particles force a system ... More
Lepton flavour violating Higgs and tau to mu gammaJan 04 2010Jun 13 2010We update phenomenological constraints on a Two Higgs Doublet Model with lepton flavour non-conserving Yukawa couplings. We review that $\tan \beta$ is ambiguous in such "Type III" models, and define it from the $\tau$ Yukawa coupling. The neutral scalars ... 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
Time crystals: a reviewApr 12 2017Jan 18 2018Time crystals are time-periodic self-organized structures postulated by Frank Wilczek in 2012. While the original concept was strongly criticized, it stimulated at the same time an intensive research leading to propositions and experimental verifications ... More
Baryogenesis in Models with a Low Quantum Gravity ScaleOct 07 1998Dec 08 1998We make generic remarks about baryogenesis in models where the scale $M_s$ of quantum gravity is much below the Planck scale. These correspond to M-theory vacua with a large volume for the internal space. Baryogenesis is a challenge, particularly for ... 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
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
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
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
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
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
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