Results for "V. J. S. Bejar"

total 326409took 0.15s
GTC OSIRIS z-band imaging of Y dwarfsJan 15 2013The aim of the project is to contribute to the characterisation of the spectral energy distribution of the coolest brown dwarfs discovered to date, the Y dwarfs. We obtained z-band far-red imaging for six Y dwarfs and a T9+Y0 binary with the OSIRIS (Optical ... More
Spectroscopy of Hyades L dwarf candidatesOct 01 2014We present the results of photometric, astrometric, and spectroscopic follow-up of L dwarf candidates identified in the Hyades cluster by Hogan et al. (2008). We obtained low-resolution optical spectroscopy with the OSIRIS spectrograph on the Gran Telescopio ... More
Optical and infrared photometry of new very low-mass stars and brown dwarfs in the Sigma Orionis clusterApr 06 2004We present an RI photometric survey covering an area of 430 arcmin^2 around the multiple star Sigma Orionis. The observations were conducted with the 0.8 m IAC-80 Telescope at the Teide Observatory. The survey limiting R and I magnitudes are 22.5 and ... More
A Search for Very Low-mass Stars and Brown Dwarfs in the Young sigma Orionis ClusterMar 15 1999We present a CCD-based photometric survey covering 870 sq. arcmin in a young stellar cluster around the young multiple star sigma Orionis. Our survey limiting R, I, and Z magnitudes are 23.2, 21.8, and 21.0, respectively. From our colour-magnitude diagrams, ... More
Discovery of a Low-Mass Brown Dwarf Companion of the Young Nearby Star G196-3Nov 25 1998A substellar-mass object in orbit at about 300 astronomical units (AU) from the young low-mass star G196-3 was detected by direct imaging. Optical and infrared photometry and low- and intermediate-resolution spectroscopy of the faint companion, hereafter ... More
Optical Linear Polarization of Late M- and L-Type DwarfsNov 18 2004(Abridged). We report on the linear polarimetric observations in the Johnson I filter of 44 M6-L7.5 ultracool dwarfs (2800-1400 K). Eleven (10 L and 1 M) dwarfs appear to have significant linear polarization (P = 0.2-2.5%). We have compared the M- and ... More
Photometric variability of young brown dwarfs in the sigma Orionis open clusterJun 15 2004We have carried out multi-epoch, time-series differential I-band photometry of a large sample of objects in the south-east region of the young (~3 Myr), nearby (~350 pc) sigma Orionis open cluster. A field of ~1000 arcmin^2 was monitored during four nights ... More
Photometric variability of a young, low-mass brown dwarfJun 19 2003We report differential I-band and J-band photometry of S Ori 45, a cool (M8.5), young (1-8 Myr) brown dwarf of the sigma Orionis cluster with a likely mass estimated at around 20 times the mass of Jupiter. We detect variability (amplitudes ranging from ... More
An L-type substellar object in Orion: reaching the mass boundary between brown dwarfs and giant planetsAug 19 1999We present J-band photometry and low-resolution optical spectroscopy (600-1000 nm) for one of the faintest substellar member candidates in the young sigma Ori cluster, SOri 47 (I=20.53, Bejar et al. 1999). Its very red (I-J)=3.3+/-0.1 color and its optical ... More
Flare activity and photospheric analysis of Proxima CentauriJun 14 2017We present the analysis of emission lines in high-resolution optical spectra of the planet-host star Proxima Centauri (Proxima) classified as a M5.5V\@. We carry out the detailed analysis of observed spectra to get a better understanding of the physical ... More
Space Velocities of L- and T-type DwarfsJun 06 2007(Abridged) We have obtained radial velocities of a sample of 18 ultracool dwarfs (M6.5-T8) using high-resolution, near-infrared spectra obtained with NIRSPEC and the Keck II telescope. We have confirmed that the radial velocity of Gl 570 D is coincident ... More
Proper motion Pleiades candidate L-type brown dwarfsNov 09 2005We present results of an optical and near-infrared (IR) 1.8 deg^2 survey in the Pleiades open cluster to search for substellar objects. From optical I-band images from the CFHT and J-band images from the 3.5 m CAHA Telescope, we identify 18 faint and ... More
A New Pleiades Member at the Lithium Substellar BoundaryMar 19 1998We present the discovery of an object in the Pleiades open cluster, named Teide 2, with optical and infrared photometry which place it on the cluster sequence slightly below the expected substellar mass limit. We have obtained low- and high-resolution ... More
A search for planetary-mass objects and brown dwarfs in the Upper Scorpius associationAug 12 2005We report the results of a deep photometric search for planets and brown dwarfs in the nearby young OB Upper Scorpius association. We obtained optical (I) and near-infrared (JKs) images around nine very low-mass stars and brown dwarf member candidates ... More
Activity at the Deuterium-Burning Mass Limit in OrionMar 18 2002We report very intense and variable Halpha emission (pseudo-equivalent widths of ~180, 410 A) of S Ori 55, a probable free-floating, M9-type substellar member of the young sigma Orionis open star cluster. After comparison with state-of-the-art evolutionary ... More
2MASS J154043.42-510135.7: a new addition to the 5 pc populationMay 21 2014The aim of the project is to find the stars nearest to the Sun and to contribute to the completion of the stellar and substellar census of the solar neighbourhood. We identified a new late-M dwarf within 5 pc, looking for high proper motion sources in ... More
Keck NIRC Observations of Planetary-mass Candidate Members in the sigma Orionis Open ClusterAug 03 2001We present K-band photometry and low-resolution near-infrared spectroscopy from 1.44 to 2.45 micron of isolated planetary-mass candidate members in the sigma Orionis cluster found by Zapatero Osorio et al. The new data have been obtained with NIRC at ... More
VLT X-shooter spectroscopy of the nearest brown dwarf binaryJun 29 2015The aim of the project is to characterise both components of the nearest brown dwarf sytem to the Sun, WISE J104915.57-531906.1 (=Luhman16AB) at optical and near-infrared wavelengths. We obtained high signal-to-noise intermediate-resolution (R~6000-11000) ... More
Temporal changes of the flare activity of Proxima CenMay 17 2019We study temporal variations of the emission lines of Halpha, Hepsilon, H and K Ca II, D1 and D2 Na I, 4026 and 5876 A He I in the HARPS spectra of Proxima Centauri across an extended time of 13.2 years, from May 27, 2004, to September 30, 2017. Aims. ... More
Binary frequency of planet-host stars at wide separations: A new brown dwarf companion to a planet-host starAug 06 2014The aim of the project is to improve our knowledge on the multiplicity of planet-host stars at wide physical separations. We cross-matched approximately 6200 square degree area of the Southern sky imaged by the Visible Infrared Survey Telescope for Astronomy ... More
Lithium and Halpha in stars and brown dwarfs of sigma OrionisFeb 07 2002We present intermediate- and low-resolution optical spectra around Halpha and LiI 6708 A for a sample of 25 low mass stars and 2 brown dwarfs with confirmed membership in the pre-main sequence stellar sigma Orionis cluster. Our observations are intended ... More
Polarisation of very-low-mass stars and brown dwarfsApr 01 2009Apr 02 2009Ultra-cool dwarfs of the L spectral type (Teff=1400-2200K) are known to have dusty atmospheres. Asymmetries of the dwarf surface may arise from rotationally-induced flattening and dust-cloud coverage, and may result in non-zero linear polarisation through ... More
A Methane Isolated Planetary Mass Object in OrionJun 20 2002We report on the discovery of a free-floating methane dwarf toward the direction of the young star cluster sigma Orionis. Based on the object's far-red optical and near-infrared photometry and spectroscopy, we conclude that it is a possible member of ... More
A search for substellar members in the Praesepe and sigma Orionis clustersSep 11 2006(Abridged). We have conducted deep photometric searches for substellar members of the Praesepe (0.5-1 Gyr) and sigma Orionis (3 Myr) star clusters using the Sloan i' and z' filters, the 3.5-m and the 5-m Hale telescopes on the Calar Alto and Palomar Observatories, ... More
Pleiades low-mass brown dwarfs: the cluster L dwarf sequenceAug 11 2006Aug 12 2006We present a search for low-mass brown dwarfs in the Pleiades open cluster. The identification of Pleiades members fainter and cooler than those currently known allows us to constrain evolutionary models for L dwarfs and to extend the study of the cluster ... More
Discovery of a wide companion near the deuterium burning mass limit in the Upper Scorpius associationDec 20 2007We present the discovery of a companion near the deuterium burning mass limit located at a very wide distance, at an angular separation of 4.6+/-0.1 arcsec (projected distance of ~ 670 AU) from UScoCTIO108, a brown dwarf of the very young Upper Scorpius ... More
Multiplicity of very low-mass objects in the Upper Scorpius OB association: a possible wide binary populationDec 09 2005We report the initial results of a VLT/NACO high spatial resolution imaging survey for multiple systems among 58 M-type members of the nearby Upper Scorpius OB association. Nine pairs with separations below 100 have been resolved. Their small angular ... More
CARMENES input catalogue of M dwarfs II. High-resolution imaging with FastCamAug 29 2016Aims: We search for low-mass companions of M dwarfs and characterize their multiplicity fraction with the purpose of helping in the selection of the most appropriate targets for the CARMENES exoplanet survey. Methods: We obtained high-resolution images ... More
SafetyMay 26 2017Chapter 17 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered ... More
High contrast optical imaging of companions: the case of the brown dwarf binary HD-130948BCSep 28 2010High contrast imaging at optical wavelengths is limited by the modest correction of conventional near-IR optimized AO systems.We take advantage of new fast and low-readout-noise detectors to explore the potential of fast imaging coupled to post-processing ... More
An eclipsing double-line spectroscopic binary at the stellar/substellar boundary in the Upper Scorpius OB associationNov 10 2015We aim at constraining evolutionary models at low mass and young ages by identifying interesting transiting system members of the nearest OB association to the Sun, Upper Scorpius, targeted by the Kepler mission. We produced light curves for M dwarf members ... More
New constraints on the membership of the T dwarf S Ori 70 in the sigma Orionis clusterOct 15 2007(Abridged) The nature of S Ori 70, a faint mid-T type object found towards the direction of the young sigma Orionis cluster, is still under debate. We intend to disentangle whether it is a field brown dwarf or a 3-Myr old planetary-mass member of the ... More
High spatial resolution and high contrast optical speckle imaging with FASTCAM at the ORMSep 23 2010In this paper, we present an original observational approach, which combines, for the first time, traditional speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high contrast (1e-5) within 0.5 to ... More
The Substellar Mass Function in sigma OrionisApr 05 2001We combine results from imaging searches for substellar objects in the sigma Orionis cluster and follow-up photometric and spectroscopic observations to derive a census of the brown dwarf population in a region of 847 arcmin^2. We identify 64 very low-mass ... More
CARMENES input catalogue of M dwarfs IV. New rotation periods from photometric time seriesOct 08 2018Aims. The main goal of this work is to measure rotation periods of the M-type dwarf stars being observed by the CARMENES exoplanet survey to help distinguish radial-velocity signals produced by magnetic activity from those produced by exoplanets. Rotation ... More
A deep WISE search for very late type objects and the discovery of two halo/thick-disk T dwarfs: WISE 0013+0634 and WISE 0833+0052Aug 02 2013A method is defined for identifying late T and Y dwarfs in WISE down to low values of signal-to-noise. This requires a WISE detection only in the W2-band and uses the statistical properties of the WISE multi-frame measurements and profile fit photometry ... More
The CARMENES search for exoplanets around M dwarfs - Photospheric parameters of target stars from high-resolution spectroscopyFeb 08 2018The new CARMENES instrument comprises two high-resolution and high-stability spectrographs that are used to search for habitable planets around M dwarfs in the visible and near-infrared regime via the Doppler technique. Characterising our target sample ... More
Discovery of a very cool object with extraordinarily strong H(alpha) emissionAug 28 2002We report on the finding of the strongest H(alpha) emission -pseudoequivalent width of 705 Angstrom- known so far in a young, late type dwarf. This object, named as SOri71, is a substellar candidate member of the 1-8 Myr star cluster sigma Orionis. Due ... More
The Disappearing Act of KH 15D: Photometric Results from 1995 to 2004Jul 25 2005We present results from the most recent (2002-2004) observing campaigns of the eclipsing system KH 15D, in addition to re-reduced data obtained at Van Vleck Observatory (VVO) between 1995 and 2000. Phasing nine years of photometric data shows substantial ... More
First T dwarfs in the VISTA Hemisphere SurveyOct 18 2012The aim of the project is to improve our current knowledge of the density of T dwarfs and the shape of the substellar initial mass function by identifying a magnitude-limited sample of T dwarfs in the full southern sky. We present the results of a photometric ... More
The CARMENES search for exoplanets around M dwarfs: Different roads to radii and masses of the target starsApr 05 2019We determine the radii and masses of 293 nearby, bright M dwarfs of the CARMENES survey. This is the first time that such a large and homogeneous high-resolution (R>80 000) spectroscopic survey has been used to derive these fundamental stellar parameters. ... More
CARMENES: Calar Alto high-Resolution search for M dwarfs with Exo-earths with a Near-infrared Echelle SpectrographDec 03 2009CARMENES, Calar Alto high-Resolution search for M dwarfs with Exo-earths with a Near-infrared Echelle Spectrograph, is a study for a next-generation instrument for the 3.5m Calar Alto Telescope to be designed, built, integrated, and operated by a consortium ... More
Top Quark Physics at CollidersOct 07 2004Oct 09 2004We review some recent developments in top quark production and decay at current and future colliders.
The K2-ESPRINT Project II: Spectroscopic follow-up of three exoplanet systems from Campaign 1 of K2Feb 04 2016We report on Doppler observations of three transiting planet candidates that were detected during Campaign 1 of the K2 mission. The Doppler observations were conducted with FIES, HARPS-N and HARPS. We measure the mass of K2-27b (EPIC 201546283b), and ... More
Collider aspects of flavour physics at high QJan 11 2008This review presents flavour related issues in the production and decays of heavy states at LHC, both from the experimental side and from the theoretical side. We review top quark physics and discuss flavour aspects of several extensions of the Standard ... More
FCNC top quark decays beyond the Standard ModelJan 26 2001Flavor Changing Neutral Current decays of the top quark within the strict context of the Standard Model are known to be extremely rare. In fact, they are hopelessly undetectable at the Tevatron, LHC and LC in any of their scheduled upgradings. Therefore, ... More
The nuclear Schiff moment and time invariance violation in atomsAug 03 2001Mar 13 2002Parity and time invariance violating (P,T-odd) nuclear forces produce P,T-odd nuclear moments. In turn, these moments can induce electric dipole moments (EDMs) in atoms through the mixing of electron wavefunctions of opposite parity. The nuclear EDM is ... More
Loop Induced Flavor Changing Neutral Decays of the Top Quark in a General Two-Higgs-Doublet ModelNov 07 2000Feb 13 2001Decays of the top quark induced by flavor changing neutral currents (FCNC) are known to be extremely rare events within the Standard Model. This is so not only for the decay modes into gauge bosons, but most notably in the case of the Higgs channels, ... More
Violations of fundamental symmetries in atoms and tests of unification theories of elementary particlesSep 12 2003High-precision measurements of violations of fundamental symmetries in atoms are a very effective means of testing the standard model of elementary particles and searching for new physics beyond it. Such studies complement measurements at high energies. ... More
Laser Excitation of Polarization Waves in a Frozen GasAug 16 1999Apr 18 2000Laser experiments with optically excited frozen gases entail the excitation of polarization waves. In a continuum approximation the waves are dispersionless, but their frequency depends on the direction of the propagation vector. An outline is given of ... More
Resonant Processes and Exciton Propagation in a Frozen GasAug 30 2000Sep 12 2000We present numerical simulations of a theory of resonant processes in a frozen gas of excited atoms interacting via dipole-dipole potentials that vary as $r^{-3}$, where $r$ is the interatomic separation. The simulations calculate time-dependent averages ... More
Isospin breaking corrections to nucleon form factors in the constituent quark modelApr 27 1995We examine isospin breaking in the nucleon wave functions due to the $u - d$ quark mass difference and the Coulomb interaction among the quarks, and their consequences on the nucleon electroweak form factors in a nonrelativistic constituent quark model. ... More
Forward Modeling of Synthetic EUV/SXR Emission from Solar Coronal Active Regions: Case of AR 11117Sep 12 2014Recent progress in obtaining high spatial resolution images of the solar corona in the extreme-ultraviolet (EUV) with Hinode, TRACE, SDO and recent Hi-C missions and soft X-ray (SXR) bands opened a new avenue in understanding the solar coronal heating, ... More
Completely reducible hypersurfaces in a pencilJan 10 2007Apr 09 2007We study completely reducible fibers of pencils of hypersurfaces on $\mathbb P^n$ and associated codimension one foliations of $\mathbb P^n$. Using methods from theory of foliations we obtain certain upper bounds for the number of these fibers as functions ... More
Renormalization group method for weakly coupled quantum chains: comparison with exact diagonalizationFeb 20 2004We show that numerical quasi-one-dimensional renormalization group allows accurate study of weakly coupled chains with modest computational effort. We perform a systematic comparison with exact diagonalization results in two and three-leg spin ladders ... More
Production and FCNC decay of supersymmetric Higgs bosons into heavy quarks in the LHCAug 03 2005Oct 31 2005We analyze the production and subsequent decay of the neutral MSSM Higgs bosons (h = h^0, H^0, A^0) mediated by flavor changing neutral currents (FCNC) in the LHC collider. We have computed the h-production cross-section times the FCNC branching ratio, ... More
The radiative potential method for calculations of QED radiative corrections to energy levels and electromagnetic amplitudes in many-electron atomsJul 08 2005We derive an approximate expression for a "radiative potential" which can be used to calculate QED strong Coulomb field radiative corrections to energies and electric dipole (E1) transition amplitudes in many-electron atoms with an accuracy of a few percent. ... More
Molecular Bose-Einstein condensate as an amplifier of weak interactionsJul 26 2002Collisions and chemical reactions of molecules in Bose-Einstein condensates (BECs) are extremely sensitive to weak fields. This sensitivity arises due to the high density of compound resonances and a macroscopic number of molecules with kinetic energy ... More
Resonance reactions and enhancement of weak interactions in collisions of cold moleculesMar 24 2006Aug 24 2006With the creation of ultracold atoms and molecules, a new type of chemistry - "resonance" chemistry - emerges: chemical reactions can occur when the energy of colliding atoms and molecules matches a bound state of the combined molecule (Feshbach resonance). ... More
The K2-ESPRINT Project V: a short-period giant planet orbiting a subgiant starMay 30 2016We report on the discovery and characterization of the transiting planet K2-39b (EPIC 206247743b). With an orbital period of 4.6 days, it is the shortest-period planet orbiting a subgiant star known to date. Such planets are rare, with only a handful ... More
The performance of an idealized large-area array of moderate-sized IACTsAug 20 2007We present simulations of a large array of imaging atmospheric Cherenkov telescopes (IACTs), for which the size of the array footprint is much larger than the size of the Cherenkov lightpool. To evaluate limitations of the imaging atmospheric Cherenkov ... More
General soliton matrices in the Riemann-Hilbert problem for integrable nonlinear equationsJun 16 2003We derive the soliton matrices corresponding to an arbitrary number of higher-order normal zeros for the matrix Riemann-Hilbert problem of arbitrary matrix dimension, thus giving the complete solution to the problem of higher-order solitons. Our soliton ... More
Energy range of hadronic calorimeter towers and cells for high-pT jets at a 100 TeV colliderNov 04 2015Dec 28 2015This paper discusses a study of tower and cell energy ranges of a hadronic calorimeter for a 100 TeV pp collider. The dynamic energy ranges were estimated using Standard Model jets with transverse momenta above 20 TeV. The simulations were performed using ... More
Conductivity close to antiferromagnetic criticalityJul 14 2012Jan 02 2013We study the conductivity of a 3D disordered metal close to the antiferromagnetic instability within the framework of the spin-fermion model using the diagrammatic technique. We calculate the interaction correction $\delta\sigma(\omega,T)$ to the conductivity, ... More
Schwarzschild-Couder two-mirror telescope for ground-based gamma-ray astronomyAug 21 2007Schwarzschild-type aplanatic telescopes with two aspheric mirrors, configured to correct spherical and coma aberrations, are considered for application in gamma-ray astronomy utilizing the ground-based atmospheric Cherenkov technique. We use analytical ... More
Higgs Boson Flavor-Changing Neutral Decays into Top Quark in a General Two-Higgs-Doublet ModelJul 10 2003Oct 03 2003Higgs boson decays mediated by flavor changing neutral currents (FCNC) are very much suppressed in the Standard Model, at the level of 10^{-15} for Higgs boson masses of a few hundred GeV. Therefore, any experimental vestige of them would immediately ... More
SUSY Higgs boson flavor-changing neutral currents at the LHCJan 23 2006Jan 30 2006We compute and analyze the Flavor-Changing Neutral Current (FCNC) interactions of Minimal Supersymmetric Standard Model Higgs bosons (h = h0, H0, A0) with heavy quarks (top and bottom), focusing on the strongly-interacting sector. We correlate the Higgs ... More
Duality of metric entropyJul 14 2004For two convex bodies K and T in $R^n$, the covering number of K by T, denoted N(K,T), is defined as the minimal number of translates of T needed to cover K. Let us denote by $K^o$ the polar body of K and by D the euclidean unit ball in $R^n$. We prove ... More
Transition Redshift: New Kinematic Constraints from SupernovaeMay 09 2008Jul 02 2008The transition redshift (deceleration/acceleration) is discussed by expanding the deceleration parameter to first order around its present value. A detailed study is carried out by considering two different parameterizations: $q=q_0 + q_1z$ and $q=q_0 ... More
Structure, classifcation, and conformal symmetry, of elementary particles over non-archimedean space-timeMay 08 2009It is known that no length or time measurements are possible in sub-Planckian regions of spacetime. The Volovich hypothesis postulates that the micro-geometry of spacetime may therefore be assumed to be non-archimedean. In this letter, the consequences ... More
Disordered and Ordered States in a Frustrated Anisotropic Heisenberg HamiltonianMar 15 2004We use a recently proposed perturbative numerical renormalization group algorithm to investigate ground-state properties of a frustrated three dimensional Heisenberg model on an anisotropic lattice. We analyze the ground state energy, the finite size ... More
A 3% Determination of $H_0$ at Intermediate RedshiftsJun 02 2012Dec 10 2013Recent determinations of the Hubble constant, H_0, at extremely low and very high redshifts based on the cosmic distance ladder (grounded with trigonometric parallaxes) and a cosmological model (applied to Planck 2013 data) respectively, are revealing ... More
Deflationary cosmology: constraints from angular size and ages of globular clustersFeb 13 2002Jul 02 2002Observational constraints to a large class of decaying vacuum cosmologies are derived using the angular size data of compact radio sources and the latest age estimates of globular clusters. For this class of deflationary $\Lambda(t)$ models, the present ... More
Constraining the dark energy with galaxy clusters X-ray dataMar 17 2003The equation of state characterizing the dark energy component is constrained by combining Chandra observations of the X-ray luminosity of galaxy clusters with independent measurements of the baryonic matter density and the latest measurements of the ... More
Atomic electric dipole moments of He and Yb induced by nuclear Schiff momentsMay 28 2007We have calculated the atomic electric dipole moments (EDMs) d of ^3He and ^{171}Yb induced by their respective nuclear Schiff moments S. Our results are d(He)= 8.3x10^{-5} and d(Yb)= -1.9 in units 10^{-17}S/(e{fm}^3)e cm. By considering the nuclear Schiff ... More
Calculation of parity and time invariance violation in the radium atomDec 14 1999Parity (P) and time (T) invariance violating effects in the Ra atom are strongly enhanced due to close states of opposite parity, the large nuclear charge Z and the collective nature of P,T-odd nuclear moments. We have performed calculations of the atomic ... More
The atomic electric dipole moment induced by the nuclear electric dipole moment; the magnetic moment effectDec 03 2010Mar 02 2011We have considered a mechanism for inducing a time-reversal violating electric dipole moment (EDM) in atoms through the interaction of a nuclear EDM (d_N) with the hyperfine interaction, the "magnetic moment effect". We have derived the operator for this ... More
Deformed Distance Duality Relations and Supernovae DimmingOct 23 2011The basic cosmological distances are linked by the Etherington cosmic distance duality relation, $\eta (z) = D_{L}(z)(1+z)^{-2}/D_{A}(z) \equiv 1$, where $D_{L}$ and $D_{A}$ are, respectively, the luminosity and angular diameter distances. In order to ... More
Martensite-like transition and spin-glass behavior in nanocrystalline Pr0.5Ca0.5MnO3Apr 04 2012We report on isothermal pulsed (20 ms) field magnetization, temperature dependent AC - susceptibility, and the static low magnetic field measurements carried out on 10 nm sized Pr0.5Ca0.5MnO3 nanoparticles (PCMO10). The saturation field for the magnetization ... More
Calculations of parity nonconserving s-d transitions in Cs, Fr, Ba II, and Ra IIJan 08 2001We have performed ab initio mixed-states and sum-over-states calculations of parity nonconserving (PNC) electric dipole (E1) transition amplitudes between s-d electron states of Cs, Fr, Ba II, and Ra II. For the lower states of these atoms we have also ... More
Calculation of parity nonconservation in cesium and possible deviation from the Standard ModelNov 02 2001We have calculated the 6s-7s parity nonconserving E1 transition amplitude (E_{PNC}) in cesium. This calculation has been performed with higher numerical accuracy than our 1989 calculation [V.A. Dzuba, V.V. Flambaum, and O.P. Sushkov, Phys. Lett. A {\bf ... More
Simplified Quartessence CosmologyOct 31 2006Jan 14 2009We propose a new class of accelerating world models unifying the cosmological dark sector (dark matter and dark energy). All the models are described by a simplified version of the Chaplygin gas Quartessence cosmology. It is found that even for $\Omega_k ... More
Cosmological constraints on Chaplygin gas dark energy from galaxy clusters X-ray and supernova dataJun 16 2003Feb 02 2004The recent observational evidences for the present accelerated stage of the Universe have stimulated renewed interest for alternative cosmologies. In general, such models contain an unknown negative-pressure dark component that explains the supernova ... More
A simplified approach for Chaplygin-type cosmologiesAug 22 2006A new class of accelerating cosmological models driven by a one-parameter version of the general Chaplygin-type equation of state is proposed. The simplified version is naturally obtained from causality considerations with basis on the adiabatic sound ... More
Cosmological implications of APM 08279+5255, an old quasar at z = 3.91Jan 13 2003Mar 04 2003The existence of old high-redshift objects provides an important tool for constraining the expanding age of the Universe and the formation epoch of the first objects. In a recent paper, Hasinger {\it et al.} (2002) reported the discovery of the quasar ... More
Magnetocaloric effect and nature of magnetic transition in nanoscale Pr0.5Ca0.5MnO3Sep 27 2012Systematic measurements pertinent to the magnetocaloric effect and nature of magnetic transition around the transition temperature are performed in the 10 nm Pr0.5Ca0.5MnO3 nanoparticles (PCMO10) . Maxwell relation is employed to estimate the change in ... More
Precise calculation of parity nonconservation in cesium and test of the standard modelApr 12 2002We have calculated the 6s-7s parity nonconserving (PNC) E1 transition amplitude, E_{PNC}, in cesium. We have used an improved all-order technique in the calculation of the correlations and have included all significant contributions to E_{PNC}. Our final ... More
Oscillatory exchange bias and training effects in nanocrystalline Pr0.5Ca0.5MnO3Apr 04 2012We report on exchange bias effects in 10 nm particles of Pr0.5Ca0.5MnO3 which appear as a result of competing interactions between the ferromagnetic (FM)/anti-ferromagnetic (AFM) phases. The fascinating new observation is the demonstration of the temperature ... More
Reddenings and metallicities in the LMC and SMC from Stroemgren CCD photometryDec 01 2000The individual reddenings for B stars in two fields in the Small Magellanic Cloud (SMC) and two fields in the Large Magellanic Cloud (LMC) are determined by means of Stroemgren uvby CCD photometry. In both LMC fields we find a foreground reddening of ... More
Eclipsing binaries in the Magellanic Clouds. uvby CCD light curves and photometric analyses for HV982 (LMC), HV12578 (LMC), HV1433 (SMC), and HV11284 (SMC)Feb 28 2003We present new accurate CCD uvby light curves for the LMC eclipsing binaries HV982 and HV12578, and for the SMC systems HV1433 and HV11284 obtained at the Danish 1.5m telescope at ESO, La Silla. The light curves were derived from DoPHOT photometry, and ... More
The Density Matrix Renormalization Group Method for Realistic Large-Scale Nuclear Shell-Model CalculationsJul 11 2002The Density Matrix Renormalization Group (DMRG) method is developed for application to realistic nuclear systems. Test results are reported for 24Mg.
The Density Matrix Renormalization Group Method and Large-Scale Nuclear Shell-Model CalculationsFeb 15 2002The particle-hole Density Matrix Renormalization Group (p-h DMRG) method is discussed as a possible new approach to large-scale nuclear shell-model calculations. Following a general description of the method, we apply it to a class of problems involving ... More
Relaxation of Bose-Einstein Condensates of Magnons in Magneto-Textural Traps in Superfluid $^3$He-BJul 25 2013Nov 05 2013In superfluid $^3$He-B externally pumped quantized spin-wave excitations or magnons spontaneously form a Bose-Einstein condensate in a 3-dimensional trap created with the order-parameter texture and a shallow minimum in the polarizing field. The condensation ... More
Quantum Interference Effects in Slowly Rotating NUT Space-timeApr 17 2008Apr 20 2008General relativistic quantum interference effects in the slowly rotating NUT space-time as the Sagnac effect and the phase shift effect of interfering particle in neutron interferometer are considered. It was found that in the case of the Sagnac effect ... More
Irreversible Multilayer AdsorptionFeb 20 1993Random sequential adsorption (RSA) models have been studied due to their relevance to deposition processes on surfaces. The depositing particles are represented by hard-core extended objects; they are not allowed to overlap. Numerical Monte Carlo studies ... More
Collective Effects in Random Sequential Adsorption of Diffusing Hard SquaresOct 24 1992We study by Monte Carlo computer simulations random sequential adsorption (RSA) with diffusional relaxation, of lattice hard squares in two dimensions. While for RSA without diffusion the coverage approaches its maximum jamming value (large-time fractional ... More
Gravitational waves in a stringlike fluid cosmologyJun 03 1998The coupling of a stringlike fluid with ordinary matter and gravity may lead to a closed Universe with the dynamic of an open one. This can provide an alternative solution for the age and horizon problems. A study of density perturbations of the stringlike ... More
Vibrational and stochastic resonances in two coupled overdamped anharmonic oscillatorsNov 10 2006We study the overdamped version of two coupled anharmonic oscillators under the influence of both low- and high-frequency forces respectively and a Gaussian noise term added to one of the two state variables of the system. The dynamics of the system is ... More
Classical and quantum partition bound and detector inefficiencyMar 19 2012Jul 02 2014We study randomized and quantum efficiency lower bounds in communication complexity. These arise from the study of zero-communication protocols in which players are allowed to abort. Our scenario is inspired by the physics setup of Bell experiments, where ... More
Strong-field effects in Rabi oscillations between a single state and a superposition of statesSep 22 2011Rabi oscillations of quantum population are known to occur in two-level systems driven by spectrally narrow laser fields. In this work we study Rabi oscillations induced by shaped broadband femtosecond laser pulses. Due to the broad spectral width of ... More