Results for "M. Alfonsi"

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Exact and high order discretization schemes for Wishart processes and their affine extensionsJun 11 2010Mar 13 2013This work deals with the simulation of Wishart processes and affine diffusions on positive semidefinite matrices. To do so, we focus on the splitting of the infinitesimal generator, in order to use composition techniques as Ninomiya and Victoir or Alfonsi. ... More
A simple proof for the convexity of the Choquet integralJan 07 2015This note presents an elementary and direct proof for the convexity of the Choquet integral when the corresponding set function is submodular.
Un successeur de Bouguer : Étienne Bézout (1730 -- 1783) commissaire pour la marine à l'Académie royale des sciencesOct 20 2009Jan 05 2010\'Etienne B\'ezout, member of the Acad\'emie Royale des Sciences, have to study some works and books sended at the Acad\'emy. In this article, we will look at this responsibility for Navy, before and after 1764, which is the year of B\'ezout's nomination ... More
Étienne Bézout : Analyse algébrique au siècle des LumièresOct 19 2009The topic of this paper is, on the one hand to introduce algebraic analysis results of \'Etienne B\'ezout (1730- 1783) not as we know them today but as he found them in his time, and on the other hand to emphasize his innovating viewpoints. We will be ... More
A Mean-Reverting SDE on Correlation matricesAug 26 2011Feb 13 2012We introduce a mean-reverting SDE whose solution is naturally defined on the space of correlation matrices. This SDE can be seen as an extension of the well-known Wright-Fisher diffusion. We provide conditions that ensure weak and strong uniqueness of ... More
Dynamic optimal execution in a mixed-market-impact Hawkes price modelApr 02 2014Jun 09 2015We study a linear price impact model including other liquidity takers, whose flow of orders either follows a Poisson or a Hawkes process. The optimal execution problem is solved explicitly in this context, and the closed-formula optimal strategy describes ... More
Capacitary measures for completely monotone kernels via singular controlJan 13 2012Feb 25 2013We give a singular control approach to the problem of minimizing an energy functional for measures with given total mass on a compact real interval, when energy is defined in terms of a completely monotone kernel. This problem occurs both in potential ... More
Construction of the first full-size GEM-based prototype for the CMS high-$η$ muon systemDec 07 2010Dec 09 2010In view of a possible extension of the forward CMS muon detector system and future LHC luminosity upgrades, Micro-Pattern Gas Detectors (MPGDs) are an appealing technology. They can simultaneously provide precision tracking and fast trigger information, ... More
Extension and calibration of a Hawkes-based optimal execution modelJun 29 2015We provide some theoretical extensions and a calibration protocol for our former dynamic optimal execution model. The Hawkes parameters and the propagator are estimated independently on financial data from stocks of the CAC40. Interestingly, the propagator ... More
Optimal execution and price manipulations in time-varying limit order booksApr 12 2012This paper focuses on an extension of the Limit Order Book (LOB) model with general shape introduced by Alfonsi, Fruth and Schied. Here, the additional feature allows a time-varying LOB depth. We solve the optimal execution problem in this framework for ... More
Optimal transport bounds between the time-marginals of a multidimensional diffusion and its Euler schemeMay 27 2014Mar 19 2015In this paper, we prove that the time supremum of the Wasserstein distance between the time-marginals of a uniformly elliptic multidimensional diffusion with coefficients bounded together with their derivatives up to the order $2$ in the spatial variables ... More
Maximum Likelihood Estimation for Wishart processesAug 13 2015Apr 15 2016In the last decade, there has been a growing interest to use Wishart processes for modelling, especially for financial applications. However, there are still few studies on the estimation of its parameters. Here, we study the Maximum Likelihood Estimator ... More
Stochastic Local Intensity Loss Models with Interacting Particle SystemsFeb 08 2013It is well-known from the work of Sch\"onbucher (2005) that the marginal laws of a loss process can be matched by a unit increasing time inhomogeneous Markov process, whose deterministic jump intensity is called local intensity. The Stochastic Local Intensity ... More
Optimal execution strategies in limit order books with general shape functionsAug 13 2007Feb 03 2010We consider optimal execution strategies for block market orders placed in a limit order book (LOB). We build on the resilience model proposed by Obizhaeva and Wang (2005) but allow for a general shape of the LOB defined via a given density function. ... More
Long-time large deviations for the multi-asset Wishart stochastic volatility model and option pricingJun 18 2018We prove a large deviations principle for the class of multidimensional affine stochastic volatility models considered in (Gourieroux, C. and Sufana, R., J. Bus. Econ. Stat., 28(3), 2010), where the volatility matrix is modelled by a Wishart process. ... More
Evolution of the Wasserstein distance between the marginals of two Markov processesJun 09 2016In this paper, we are interested in the time derivative of the Wasserstein distance between the marginals of two Markov processes. As recalled in the introduction, the Kantorovich duality leads to a natural candidate for this derivative. Up to the sign, ... More
Smile with the Gaussian term structure modelDec 23 2014Nov 04 2015We propose an affine extension of the Linear Gaussian term structure Model (LGM) such that the instantaneous covariation of the factors is given by an affine process on semidefinite positive matrices. First, we set up the model and present some important ... More
Multivariate transient price impact and matrix-valued positive definite functionsOct 16 2013Sep 09 2015We consider a model for linear transient price impact for multiple assets that takes cross-asset impact into account. Our main goal is to single out properties that need to be imposed on the decay kernel so that the model admits well-behaved optimal trade ... More
Search for Electronic Recoil Event Rate Modulation with 4 Years of XENON100 DataJan 03 2017We report on a search for electronic recoil event rate modulation signatures in the XENON100 data accumulated over a period of 4 years, from January 2010 to January 2014. A profile likelihood method, which incorporates the stability of the XENON100 detector ... More
Search for magnetic inelastic dark matter with XENON100Apr 19 2017Oct 31 2017We present the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the XENON100 science run II. This very distinct signature is predicted in the framework of magnetic ... More
The XENON1T Dark Matter ExperimentAug 23 2017The XENON1T experiment at the Laboratori Nazionali del Gran Sasso (LNGS) is the first WIMP dark matter detector operating with a liquid xenon target mass above the ton-scale. Out of its 3.2t liquid xenon inventory, 2.0t constitute the active target of ... More
Intrinsic backgrounds from Rn and Kr in the XENON100 experimentAug 11 2017Mar 03 2018In this paper, we describe the XENON100 data analyses used to assess the target-intrinsic background sources radon ($^{222}$Rn), thoron ($^{220}$Rn) and krypton ($^{85}$Kr). We detail the event selections of high-energy alpha particles and decay-specific ... More
Signal Yields of keV Electronic Recoils and Their Discrimination from Nuclear Recoils in Liquid XenonSep 28 2017Feb 01 2018We report on the response of liquid xenon to low energy electronic recoils below 15 keV from beta decays of tritium at drift fields of 92 V/cm, 154 V/cm and 366 V/cm using the XENON100 detector. A data-to-simulation fitting method based on Markov Chain ... More
Effective field theory search for high-energy nuclear recoils using the XENON100 dark matter detectorMay 07 2017We report on WIMP search results in the XENON100 detector using a non-relativistic effective field theory approach. The data from science run II (34 kg $\times$ 224.6 live days) was re-analyzed, with an increased recoil energy interval compared to previous ... More
Results from a Calibration of XENON100 Using a Source of Dissolved Radon-220Nov 11 2016Apr 25 2017A Rn-220 source is deployed on the XENON100 dark matter detector in order to address the challenges in calibration of tonne-scale liquid noble element detectors. We show that the Pb-212 beta emission can be used for low-energy electronic recoil calibration ... More
Online $^{222}$Rn removal by cryogenic distillation in the XENON100 experimentFeb 22 2017Jun 02 2017We describe the purification of xenon from traces of the radioactive noble gas radon using a cryogenic distillation column. The distillation column is integrated into the gas purification loop of the XENON100 detector for online radon removal. This enabled ... More
Removing krypton from xenon by cryogenic distillation to the ppq levelDec 13 2016May 08 2017The XENON1T experiment aims for the direct detection of dark matter in a cryostat filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by radioactive decays inside the detector has to be sufficiently ... More
Search for WIMP Inelastic Scattering off Xenon Nuclei with XENON100May 01 2017We present the first constraints on the spin-dependent, inelastic scattering cross section of Weakly Interacting Massive Particles (WIMPs) on nucleons from XENON100 data with an exposure of 7.64$\times$10$^3$\,kg\,day. XENON100 is a dual-phase xenon time ... More
Material radioassay and selection for the XENON1T dark matter experimentMay 04 2017The XENON1T dark matter experiment aims to detect Weakly Interacting Massive Particles (WIMPs) through low-energy interactions with xenon atoms. To detect such a rare event necessitates the use of radiopure materials to minimize the number of background ... More
First results on the scalar WIMP-pion coupling, using the XENON1T experimentNov 29 2018We present first results on the scalar WIMP-pion coupling from 1 t$\times$yr of exposure with the XENON1T experiment. This interaction is generated when the WIMP couples to a virtual pion exchanged between the nucleons in a nucleus. In contrast to most ... More
Characterization of GEM Detectors for Application in the CMS Muon Detection SystemDec 16 2010The muon detection system of the Compact Muon Solenoid experiment at the CERN Large Hadron Collider is based on different technologies for muon tracking and triggering. In particular, the muon system in the endcap disks of the detector consists of Resistive ... More
First Dark Matter Search Results from the XENON1T ExperimentMay 18 2017Nov 23 2017We report the first dark matter search results from XENON1T, a $\sim$2000-kg-target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and the first ton-scale detector of this kind. ... More
Search for Bosonic Super-WIMP Interactions with the XENON100 ExperimentSep 07 2017We present results of searches for vector and pseudo-scalar bosonic super-WIMPs, which are dark matter candidates with masses at the keV-scale, with the XENON100 experiment. XENON100 is a dual-phase xenon time projection chamber operated at the Laboratori ... More
Dark Matter Search Results from a One Tonne$\times$Year Exposure of XENON1TMay 31 2018Sep 13 2018We report on a search for Weakly Interacting Massive Particles (WIMPs) using 278.8 days of data collected with the XENON1T experiment at LNGS. XENON1T utilizes a liquid xenon time projection chamber with a fiducial mass of $(1.30 \pm 0.01)$ t, resulting ... More
Constraining the spin-dependent WIMP-nucleon cross sections with XENON1TFeb 08 2019We report the first experimental results on spin-dependent elastic WIMP-nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full tonne-year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only ... More
Proper orthogonal decomposition of solar photospheric motionsJun 27 2005The spatio-temporal dynamics of the solar photosphere is studied by performing a Proper Orthogonal Decomposition (POD) of line of sight velocity fields computed from high resolution data coming from the MDI/SOHO instrument. Using this technique, we are ... More
Spherical GEMs for parallax-free detectorsNov 17 2009We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical \textsc{gem}s are presented. Together with a spherical drift electrode, a spherical conversion gap can be formed. This would eliminate ... More
Making spherical GEMsSep 18 2009Nov 06 2009We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical GEMs are presented. Together with a spherical drift electrode, a spherical conversion gap for x-rays can be formed. This would ... More
Progress on large area GEMsSep 28 2009Nov 26 2009In 2008, a triple GEM detector prototype with an area of ~2000 cm2 has been constructed, based on foils of 66*66 cm. GEMs of such dimensions had not been made before, and innovations to the existing technology were introduced to build this detector. This ... More
Progress on large area GEMs (VCI 2010)Jul 07 2010The Gas Electron Multiplier (GEM) manufacturing technique has recently evolved to allow the production of large area GEMs. A novel approach based on single mask photolithography eliminates the mask alignment issue, which limits the dimensions in the traditional ... More
First results of spherical GEMsNov 24 2010We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical GEMs are presented. Together with a spherical drift electrode, a spherical conversion gap can be formed. This eliminates the parallax ... More
A low-mass dark matter search using ionization signals in XENON100May 20 2016Nov 03 2016We perform a low-mass dark matter search using an exposure of 30\,kg$\times$yr with the XENON100 detector. By dropping the requirement of a scintillation signal and using only the ionization signal to determine the interaction energy, we lowered the energy ... More
A low-mass dark matter search using ionization signals in XENON100May 20 2016Jun 14 2016We perform a low-mass dark matter search using an exposure of 30 kg$\times$yr with the XENON100 detector. By dropping the requirement of a scintillation signal and using only the ionization signal to determine the interaction energy, we lowered the energy ... More
Lowering the radioactivity of the photomultiplier tubes for the XENON1T dark matter experimentMar 26 2015The low-background, VUV-sensitive 3-inch diameter photomultiplier tube R11410 has been developed by Hamamatsu for dark matter direct detection experiments using liquid xenon as the target material. We present the results from the joint effort between ... More
Exclusion of Leptophilic Dark Matter Models using XENON100 Electronic Recoil DataJul 28 2015Laboratory experiments searching for galactic dark matter particles scattering off nuclei have so far not been able to establish a discovery. We use data from the XENON100 experiment to search for dark matter interacting with electrons. With no evidence ... More
Search for Event Rate Modulation in XENON100 Electronic Recoil DataJul 28 2015We have searched for periodic variations of the electronic recoil event rate in the (2-6) keV energy range recorded between February 2011 and March 2012 with the XENON100 detector, adding up to 224.6 live days in total. Following a detailed study to establish ... More
First Axion Results from the XENON100 ExperimentApr 05 2014Aug 27 2014We present the first results of searches for axions and axion-like-particles with the XENON100 experiment. The axion-electron coupling constant, $g_{Ae}$, has been tested by exploiting the axio-electric effect in liquid xenon. A profile likelihood analysis ... More
Response of the XENON100 Dark Matter Detector to Nuclear RecoilsApr 04 2013Jul 18 2013Results from the nuclear recoil calibration of the XENON100 dark matter detector installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), Italy are presented. Data from measurements with an external 241AmBe neutron source are compared ... More
The distributed Slow Control System of the XENON100 ExperimentNov 05 2012The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, was designed to search for evidence of dark matter interactions inside a volume of liquid xenon using a dual-phase time projection chamber. This paper describes ... More
The neutron background of the XENON100 dark matter experimentJun 10 2013Sep 02 2013The XENON100 experiment, installed underground at the Laboratori Nazionali del Gran Sasso (LNGS), aims to directly detect dark matter in the form of Weakly Interacting Massive Particles (WIMPs) via their elastic scattering off xenon nuclei. This paper ... More
Conceptual design and simulation of a water Cherenkov muon veto for the XENON1T experimentJun 09 2014Feb 25 2015XENON is a dark matter direct detection project, consisting of a time projection chamber (TPC) filled with liquid xenon as detection medium. The construction of the next generation detector, XENON1T, is presently taking place at the Laboratori Nazionali ... More
Analysis of the XENON100 Dark Matter Search DataJul 14 2012Oct 14 2013The XENON100 experiment, situated in the Laboratori Nazionali del Gran Sasso, aims at the direct detection of dark matter in the form of weakly interacting massive particles (WIMPs), based on their interactions with xenon nuclei in an ultra low background ... More
Observation and applications of single-electron charge signals in the XENON100 experimentNov 05 2013Jan 28 2014The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper, we report the observation ... More
Limits on spin-dependent WIMP-nucleon cross sections from 225 live days of XENON100 dataJan 28 2013Jan 29 2013We present new experimental constraints on the elastic, spin-dependent WIMP-nucleon cross section using recent data from the XENON100 experiment, operated in the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 224.6 live days x 34 kg of exposure ... More
Comment on "On the subtleties of searching for dark matter with liquid xenon detectors"Aug 28 2012In a recent manuscript (arXiv:1208.5046) Peter Sorensen claims that XENON100's upper limits on spin-independent WIMP-nucleon cross sections for WIMP masses below 10 GeV "may be understated by one order of magnitude or more". Having performed a similar, ... More
Dark Matter Results from 225 Live Days of XENON100 DataJul 25 2012Mar 20 2013We report on a search for particle dark matter with the XENON100 experiment, operated at the Laboratori Nazionali del Gran Sasso (LNGS) for 13 months during 2011 and 2012. XENON100 features an ultra-low electromagnetic background of (5.3 \pm 0.6) \times ... More
Prompt K_short production in pp collisions at sqrt(s)=0.9 TeVAug 18 2010Sep 15 2010The production of K_short mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The luminosity of the analysed sample is determined using a novel technique, involving measurements ... More
Search for Two-Neutrino Double Electron Capture of $^{124}$Xe with XENON100Sep 12 2016Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shell. For $^{124}$Xe this process has not yet been observed and its detection would provide a new reference for nuclear matrix ... More
XENON100 Dark Matter Results from a Combination of 477 Live DaysSep 20 2016We report on WIMP search results of the XENON100 experiment, combining three runs summing up to 477 live days from January 2010 to January 2014. Data from the first two runs were already published. A blind analysis was applied to the last run recorded ... More
Results from a Calibration of XENON100 Using a Source of Dissolved Radon-220Nov 11 2016A Rn-220 source is deployed on the XENON100 dark matter detector in order to address the challenges in calibration of tonne-scale liquid noble element detectors. We show that the Pb-212 beta emission can be used for low-energy electronic recoil calibration ... More
DARWIN: towards the ultimate dark matter detectorJun 22 2016DARk matter WImp search with liquid xenoN (DARWIN) will be an experiment for the direct detection of dark matter using a multi-ton liquid xenon time projection chamber at its core. Its primary goal will be to explore the experimentally accessible parameter ... More
Physics reach of the XENON1T dark matter experimentDec 23 2015Apr 15 2016The XENON1T experiment is currently in the commissioning phase at the Laboratori Nazionali del Gran Sasso, Italy. In this article we study the experiment's expected sensitivity to the spin-independent WIMP-nucleon interaction cross section, based on Monte ... More
A new signal for scalar top bound state productionOct 01 1993We study the production and decay of a scalar \stst\ bound state \sigst\ at hadron supercolliders, where \st\ is the lighter stop eigenstate. If \st\ has no tree--level 2--body decays, the dominant decay modes of \sigst\ are $gg$ or, if $m_h < \mst \ll ... More
Massive Neutrino in Non-commutative Space-timeDec 24 2007Apr 01 2008We consider the noncommutative standard model based on $SU(3)\times SU(2)\times U(1)$. We study the gauge transformation of right handed neutrino and its direct interaction with photon in the noncommutative space-time. We show that the massive Dirac neutrinos, ... More
Infinite order excitonic Bloch equations for asymmetric nanostructuresJul 04 2003We present a new exciton-based formalism for calculating the coherent response of asymmetric semiconductor multiple quantum well structures to ultra-short optical pulses valid to infinite order in the optical field and including the self-generated intraband ... More
Scalar StoponiumAug 18 1993We study the decays of a scalar \stst\ bound state \sigst, where \st\ is the lighter stop eigenstate. If \st\ has no tree--level 2--body decays, the dominant decay modes of \sigst\ are $gg$ or, if $m_h < \mst \ll \mstt$, a pair of light scalar Higgs bosons ... More
Parton Model in Lorentz Invariant Non-Commutative SpaceMay 26 2004Aug 22 2004We consider the Lorentz invariant non-commutative QED and complete the Feynman rules for the theory up to the order $\theta^2$. In the Lorentz invariant version of the non-commutative QED the particles with fractional charges can be also considered. We ... More
Electromagnetic Response of Weyl SemimetalsMar 22 2013Jun 27 2013It has been suggested recently, based on subtle field-theoretical considerations, that the electromagnetic response of Weyl semimetals and the closely related Weyl insulators can be characterized by an axion term E.B with space and time dependent axion ... More
The Charm Quark Contribution to the Proton Structure FunctionOct 14 2006Dec 27 2006The charm quark structure function $F^c_2$ and the longitudinal structure function $F_l^p$ are directly sensitive to the gluon content of proton and therefore are crucial in understanding of proton structure function, in particular at low momentum transfer ... More
Production and Decay of Scalar Stoponium Bound StatesDec 02 1993In this paper we discuss possible signatures for the production of scalar \stst\ (stoponium) bound states \sigst\ at hadron colliders, where \st\ is the lighter scalar top eigenstate. We first study the decay of \sigst; explicit expressions are given ... More
The decay of singlet scalar dark matter to unparticle and photonMay 06 2008We consider the unparticle physics introduced by Georgi and show that if the standard model is extended to include a singlet scalar as a dark matter candidate, there is a channel which leads to its decay to photon and unparticle. We calculate the decay ... More
Lorentz Conserving Noncommutative Standard ModelMar 29 2007May 10 2007We consider Lorentz conserving noncommutative field theory to construct the Lorentz conserving noncommutative standard model based on the gauge group $SU(3)\times SU(2)\times U(1)$. We obtain the enveloping algebra-valued of Higgs field up to the second ... More
Shelving and Probe Efficiency in Trapped Ion ExperimentsFeb 24 2014A generalized probe sequence typical of trapped ion experiments using shelving is studied. Detection efficiency is analyzed for finite shelved state lifetimes and using multi-modal count distributions. Multi-modal distributions are more appropriate for ... More
The Neutralino Relic Density in Minimal N=1 SupergravityJul 10 1992We compute the cosmic relic (dark matter) density of the lightest supersymmetric particle (LSP) in the framework of minimal $N=1$ Supergravity models with radiative breaking of the electroweak gauge symmetry. To this end, we re--calculate the cross sections ... More
Quantization and $2π$ Periodicity of the Axion Action in Topological InsulatorsJun 17 2010Nov 10 2010The Lagrangian describing the bulk electromagnetic response of a three-dimensional strong topological insulator contains a topological `axion' term of the form '\theta E dot B'. It is often stated (without proof) that the corresponding action is quantized ... More
Photon Neutrino Scattering in Non-Commutative SpaceNov 04 2005Jan 19 2006We extend the non-commutative standard model based on the minimal $SU(3)\times SU(2)\times U(1)$ gauge group to include the interaction of photon with neutrino. We show that, in the gauge invariant manner, only the right handed neutrino can directly couple ... More
On the effect of the thermal gas component to the stability of vortices in trapped Bose-Einstein condensatesMar 12 2002We study the stability of vortices in trapped single-component Bose-Einstein condensates within self-consistent mean-field theories--especially we consider the Hartree-Fock-Bogoliubov-Popov theory and its recently proposed gapless extensions. It is shown ... More
Quantum information processing: The case of vanishing interaction energyOct 27 2002We investigate the rate of operation of quantum "black boxes" ("oracles") and point out the possibility of performing an operation by a quantum "oracle" whose average energy equals zero. This counterintuitive result not only presents a generalization ... More
Neutralino-Nucleon Scattering RevisitedJul 01 1993We present a detailed discussion of the elastic scattering of a supersymmetric neutralino off a nucleon or nucleus, with emphasis on the spin--independent interaction. We carefully treat QCD effects on the squark exchange contribution. In particular, ... More
Phase boundaries of a spin-3/2 Blume-Emery-Griffiths model on a honeycomb latticeOct 11 2013The spin-3/2 Blume-Emery-Griffiths model on a honeycomb lattice is studied by Monte Carlo simulations with the goal to determine phase diagrams for a range of the model parameters and to investigate the nature of the phase transitions between the respective ... More
Flares on A-type stars: Evidence for heating of solar corona by nanoflares?Aug 11 2016We analyzed the occurrence rates of flares on stars of spectral types K, G, F, and A, observed by Kepler. We found that the histogram of occurrence frequencies of stellar flares is systematically shifted towards a high-energy tail for A-type stars compared ... More
The Formation Rates of Population III Stars and Chemical Enrichment of Halos during the Reionization EraJan 06 2009[abridged] The First Stars in the Universe form out of pristine primordial gas clouds that have been radiatively cooled to a few hundreds of degrees Kelvin either via molecular or atomic (Lyman-Alpha) hydrogen lines. This primordial mode of star formation ... More
Symmetry Adaptation Techniques in n-Photon Absorption SpectroscopyOct 27 1998We present some recent progress achieved in the application of symmetry adaptation techniques to n-photon absorption spectroscopy of rare earth ions in finite symmetry. More specifically, this work is concerned with the determination of the intensity ... More
Two-Photon Spectroscopy of Transition-Metal Ions in Cubical SymmetryOct 26 1998Symmetry adaptation techniques are applied to the determination of intensities of intra-configurational two-photon transitions for transition-metal ions in cubical symmetry. This leads to a simple model giving the polarization dependence of intensities ... More
An Alternative Basis for the Wigner-Racah Algebra of the Group SU(2)Dec 17 1997The Lie algebra of the classical group SU(2) is constructed from two quon algebras for which the deformation parameter is a common root of unity. This construction leads to (i) a not very well-known polar decomposition of the ladder generators of the ... More
Enhanced Sampling in the Well-Tempered EnsembleOct 26 2009Apr 13 2010We introduce the well-tempered ensemble (WTE) which is the biased ensemble sampled by well-tempered metadynamics when the energy is used as collective variable. WTE can be designed so as to have approximately the same average energy as the canonical ensemble ... More
Berry's Phase Induced Bose-Einstein condensation into a Vortex StateNov 23 1998The existence of a geometric phase in magnetic traps can be used to Bose condense a magnetically trapped atomic gas into a vortex state. We propose an experimental setup where a magnetic trap together with a blue detuned laser beam form a multiply connected ... More
Superconducting state in Fe-based materials and spin-fluctuation theory of pairingOct 28 2015Short review of the spin-fluctuation theory of superconductive pairing in iron-based pnictides and chalcogenides.
QCD_{1+1} with Static Quarks as Supersymmetric Quantum MechanicsFeb 09 1998We reexamine the solvable model problem of two static, fundamental quarks interacting with a SU(2) Yang-Mills field on a spatial circle, introduced by Engelhardt and Schreiber. If the quarks are at the same point, the model exhibits a quantum mechanical ... More
Massive Binary Black Holes in the Cosmic LandscapeJun 23 2009Binary black holes occupy a special place in our quest for understanding the evolution of galaxies along cosmic history. If massive black holes grow at the center of (pre-)galactic structures that experience a sequence of merger episodes, then dual black ... More
Einstein and the mystery of eternity of lifeApr 08 2009While Special and General Relativity are well known by a very large number of people, Einstein's religious convinctions are almost ignored. The paper focuses on what was his view about immortality. Einstein believed in Spinoza's view of God and in cosmic ... More
Effect of inelastic scattering on parametric pumpingAug 03 2001Pumping of charge in phase-coherent mesoscopic systems due to the out-of-phase modulation of two parameters has recently found considerable interest. We investigate the effect of inelastic processes on the adiabatically pumped current through a two terminal ... More
Hidden quantum pump effects in quantum coherent ringsFeb 27 2003Time periodic perturbations of an electron system on a ring are examined. For small frequencies periodic small amplitude perturbations give rise to side band currents which in leading order are inversely proportional to the frequency. These side band ... More
Dynamic scattering channels of a double barrier structureApr 02 2008We calculate analytically the Floquet scattering matrix for a periodically driven double-barrier structure. Our approach takes into account dynamical effects which become necessarily important when electrons propagate through a system subject to a fast ... More
Dissipation and noise in adiabatic quantum pumpsJan 16 2002We investigate the distribution function, the heat flow and the noise properties of an adiabatic quantum pump for an arbitrary relation of pump frequency $\omega$ and temperature. To achieve this we start with the scattering matrix approach for ac-transport. ... More
Remarks on the high-energy behaviour of cross-sections in weak-scale string theoriesSep 20 2001We consider the high-energy behaviour of processes involving Kaluza-Klein (KK) gravitons of weak-scale string theories. We discuss how form-factors derived within string theory modify the couplings of KK gravitons and thereby lead to an exponential fall-off ... More
Metastability in Two Dimensions and the Effective PotentialApr 12 1993We study analytically and numerically the decay of a metastable phase in (2+1)-dimensional classical scalar field theory coupled to a heat bath, which is equivalent to two-dimensional Euclidean quantum field theory at zero temperature. By a numerical ... More
Morphisms of Projective Varieties from the viewpoint of Minimal Model TheoryMay 22 2002In this Lecture Notes we present, in a sufficiently self contained way, our contributions and interests in the field of Minimal Model Theory. We study Fano-Mori spaces, both from the biregular and the birational point of view. For the former we recall ... More
New analyticity constraints on the high energy behavior of hadron-hadron cross sectionsJan 25 2006Mar 16 2006We here comment on a series of recent papers by Igi and Ishida[K. Igi and M. Ishida, Phys. Lett B 622, 286 (2005)] and Block and Halzen[M. M. Block and F. Halzen, Phys. Rev D 72, 036006 (2005)] that fit high energy $pp$ and $\bar pp$ cross section and ... More
Factorization Theorems for High Energy nn, gamma p and gamma gamma ScatteringFeb 17 2003The robustness of the factorization theorem for total cross sections, $\sigma_{nn}/\sigma_{\gamma p}=\sigma_{\gamma p}/\sigma_{\gamma\gamma}$, originally proved by Block and Kaidalov\cite{bk} for $nn$ (the even portion of $pp$ and $\pbar p$ scattering), ... More