Results for "A. Camposeo"

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Control of photon transport properties in nanocomposite nanowiresMar 25 2016Active nanowires and nanofibers can be realized by the electric-field induced stretching of polymer solutions with sufficient molecular entanglements. The resulting nanomaterials are attracting an increasing attention in view of their application in a ... More
3D printing of optical materials: an investigation of the microscopic propertiesJul 09 20183D printing technologies are currently enabling the fabrication of objects with complex architectures and tailored properties. In such framework, the production of 3D optical structures, which are typically based on optical transparent matrices, optionally ... More
3D photo-responsive optical devices manufactured by advanced printing technologiesApr 12 2019Photonic components responsive to external optical stimuli are attracting increasing interest, because their properties can be manipulated by light with fast switching times, high spatial definition, and potentially remote control. These aspects can be ... More
Surface-enhanced Raman spectroscopy in 3D electrospun nanofiber mats coated with gold nanorodsJul 27 2015Mar 15 2016Nanofibers functionalized by metal nanostructures and particles are exploited as effective flexible substrates for SERS analysis. Their complex three-dimensional structure may provide Raman signals enhanced by orders of magnitude compared to untextured ... More
Optimization of electrospinning techniques for the realization of nanofiber plastic lasersMar 25 2016Electrospinning technologies for the realization of active polymeric nanomaterials can be easily up-scaled, opening perspectives to industrial exploitation, and due to their versatility they can be employed to finely tailor the size, morphology and macroscopic ... More
Polymer nanofibers as novel light-emitting sources and lasing materialNov 29 2013Polymer micro- and nano-fibers, made of organic light-emitting materials with optical gain, show interesting lasing properties. Fibers with diameters from few tens of nm to few microns can be fabricated by electrospinning, a method based on electrostatic ... More
Electrospun light-emitting nanofibers as building blocks for photonics and electronicsSep 04 2013Nanomaterials made of active fibers have the potential to become new functional components of light-emitting sources in the visible and near-IR range, lasers, and electronic devices
All-optical switching in dye-doped DNA nanofibersDec 17 2018All-optical switches are introduced which are based on deoxyribonucleic acid (DNA) in the form of electrospun fibers, where DNA is semi-intercalated with a push-pull, luminescent nonlinear pyrazoline derivative. Optical birefringence is found in the organic ... More
Controlled atmosphere electrospinning of organic nanofibers with improved light emission and waveguiding propertiesOct 20 2015Nov 16 2015Electrospinning in controlled nitrogen atmosphere is developed for the realization of active polymer nanofibers. Fibers electrospun under controlled atmospheric conditions are found to be smoother and more uniform than samples realized by conventional ... More
Electrospun amplified fiber opticsFeb 25 2015Apr 06 2015A lot of research is focused on all-optical signal processing, aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for ... More
Multifunctional polymer nanofibers: UV emission, optical gain, anisotropic wetting and high hydrophobicity for next flexible excitation sourcesSep 24 2015Nov 16 2015The use of UV light sources is highly relevant in many fields of science, being directly related to all those detection and diagnosis procedures which are based on fluorescence spectroscopy. Depending on the specific application, UV light-emitting materials ... More
Bright light emission and waveguiding in conjugated polymer nanofibers electrospun from organic-salt added solutionsAug 01 2013Sep 03 2013Light emitting electrospun nanofibers of poly-[(9,9-dioctylfluorenyl-2,7-diyl)-co-(N,N'-diphenyl)-N,N'-di(p-butyl-oxy-phenyl)-1,4-diaminobenzene)] (PFO-PBAB) are produced by electrospinning under different experimental conditions. In particular, uniform ... More
Electrostatic mechanophores in tuneable light-emitting piezo-polymer nanowiresJun 02 2017Electromechanical coupling through piezoelectric polymer chains allows the emission of organic molecules in active nanowires to be tuned. This effect is evidenced by highly bendable arrays of counter-ion dye-doped nanowires made of a poly(vinylidenefluoride) ... More
Modal Coupling of Single Photon Emitters Within Nanofiber WaveguidesAug 18 2015Jun 28 2016Nanoscale generation of individual photons in confined geometries is an exciting research field aiming at exploiting localized electromagnetic fields for light manipulation. One of the outstanding challenges of photonic systems combining emitters with ... More
The conformational evolution of elongated polymer solutions tailors the polarization of light-emission from organic nanofibersJul 14 2014Jul 30 2014Polymer fibers are currently exploited in tremendously important technologies. Their innovative properties are mainly determined by the behavior of the polymer macromolecules under the elongation induced by external mechanical or electrostatic forces, ... More
Organic nanofibers embedding stimuli-responsive threaded molecular componentsOct 08 2014Oct 15 2014While most of the studies on molecular machines have been performed in solution, interfacing these supramolecular systems with solid-state nanostructures and materials is very important in view of their utilization in sensing components working by chemical ... More
A nanophotonic laser on a graphOct 18 2017Dec 20 2018Conventional nano-photonic schemes minimise multiple scattering to realise a miniaturised version of beam-splitters, interferometers and optical cavities for light propagation and lasing. Here instead, we introduce a nanophotonic network built from multiple ... More
Near-field electrospinning of conjugated polymer light-emitting nanofibersOct 18 2013Nov 11 2013The authors report on the realization of ordered arrays of light-emitting conjugated polymer nanofibers by near-field electrospinning. The fibers, made by poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], have diameters of few hundreds of nanometers ... More
Polarized superradiance from delocalized exciton transitions in tetracene single crystalsApr 30 2013Polarized superradiant emission and exciton delocalization in tetracene single crystals are reported. Polarization-, time-, and temperature-resolved spectroscopy evidence the complete polarization of the zero-phonon line of the intrinsic tetracene emission ... More
Random lasing in an organic light-emitting crystal and its interplay with vertical cavity feedbackMay 19 2014Sep 22 2014The simultaneous vertical-cavity and random lasing emission properties of a blue-emitting molecular crystal are investigated. The 1,1,4,4-tetraphenyl-1,3-butadiene samples, grown by physical vapour transport, feature room-temperature stimulated emission ... More
Sub-ms dynamics of the instability onset of electrospinningApr 10 2015May 01 2015Electrospun polymer jets are imaged for the first time at an ultra-high rate of 10,000 frames per second, investigating the process dynamics, and the instability propagation velocity and displacement in space. The polymer concentration, applied voltage ... More
Interplay of Stimulated Emission and Fluorescence Resonance Energy Transfer in Electrospun Light-Emitting FibersDec 28 2017Concomitant amplified spontaneous emission (ASE) and F\"orster resonance energy transfer (FRET) are investigated in electrospun light-emitting fibers. Upon dye-doping with a proper FRET couple system, free-standing fibrous mats exhibit tunable FRET efficiency ... More
Anisotropic conjugated polymer chain conformation tailors the energy migration in nanofibersNov 18 2016Conjugated polymers are complex multi-chromophore systems, with emission properties strongly dependent on the electronic energy transfer through active sub-units. Although the packing of the conjugated chains in the solid state is known to be a key factor ... More
Local mechanical properties of electrospun fibers correlate to their internal nanostructureOct 05 2013Nov 14 2013The properties of polymeric nanofibers can be tailored and enhanced by properly managing the structure of the polymeric molecules at the nanoscale. Although electrospun polymer fibers are increasingly exploited in many technological applications, their ... More
Physically transient photonics: random vs. distributed feedback lasing based on nanoimprinted DNAOct 08 2014Nov 07 2014The authors report on a room-temperature nanoimprinted, DNA-based distributed feedback (DFB) laser operating at 605 nm. The laser is made of a pure DNA host matrix doped with gain dyes. At high excitation densities, the emission of the untextured dye-doped ... More
Nanoparticle-doped electrospun fiber random lasers with spatially extended light modesOct 02 2017Complex assemblies of light-emitting polymer nanofibers with molecular materials exhibiting optical gain can lead to important advance to amorphous photonics and to random laser science and devices. In disordered mats of nanofibers, multiple scattering ... More
Low-defectiveness exfoliation of MoS2 nanoparticles and their embedment in hybrid light-emitting polymer nanofibersNov 17 2018Molybdenum disulfide (MoS2) has been attracting extraordinary attention for its intriguing optical, electronic and mechanical properties. Here we demonstrate hybrid, organic-inorganic light-emitting nanofibers based on MoS2 nanoparticle dopants obtained ... More
Metal-Enhanced Near-Infrared Fluorescence by Micropatterned Gold NanocagesSep 24 2015Nov 16 2015In metal-enhanced fluorescence (MEF), the localized surface plasmon resonances of metallic nanostructures amplify the absorption of excitation light and assist in radiating the consequent fluorescence of nearby molecules to the far-field. This effect ... More
Nanowire-Intensified MEF in Hybrid Polymer-Plasmonic Electrospun FilamentsApr 15 2018Hybrid polymer-plasmonic nanostructures might combine high enhancement of localized fields from metal nanoparticles with light confinement and long-range transport in subwavelength dielectric structures. Here we report on the complex behavior of fluorophores ... More
Diverse regimes of mode intensity correlation in nanofiber random lasers through nanoparticle dopingDec 27 2017Random lasers are based on disordered materials with optical gain. These devices can exhibit either intensity or resonant feedback, relying on diffusive or interference behaviour of light, respectively, which leads to either coupling or independent operation ... More
Rotational dynamics of optically trapped polymeric nanofibersJul 13 2009The optical trapping of polymeric nanofibers and the characterization of the rotational dynamics are reported. A strategy to apply a torque to a polymer nanofiber, by tilting the trapped fibers using a symmetrical linear polarized Gaussian beam is demonstrated. ... More
Biomineral Amorphous Lasers through Light-Scattering Surfaces Assembled by Electrospun Fiber TemplatesOct 25 2017New materials aim at exploiting the great control of living organisms over molecular architectures and minerals. Optical biomimetics has been widely developed by microengineering, leading to photonic components with order resembling those found in plants ... More
Electrospun Conjugated Polymer/Fullerene Hybrid Fibers: Photoactive Blends, Conductivity through Tunnelling-AFM, Light-Scattering, and Perspective for Their Use in Bulk-Heterojunction Organic Solar CellsJan 26 2018Hybrid conjugated polymer/fullerene filaments based on MEH-PPV/PVP/PCBM are prepared by electrospinning, and their properties assessed by scanning electron, atomic and lateral force, tunnelling, and confocal microscopy, as well as by attenuated total ... More
Renormalization of the Yang-Mills theory in the ambiguity-free gaugeFeb 12 2010Jul 27 2010The renormalization procedure for the Yang-Mills theory in the gauge free of the Gribov ambiguity is constructed. It is shown that all the ultraviolet infinities may be removed by renormalization of the parameters entering the classical Lagrangian and ... More
Nonreciprocal Photon Transmission and Amplification via Reservoir EngineeringFeb 25 2015Jun 05 2015We discuss a general method for constructing nonreciprocal, cavity-based photonic devices, based on matching a given coherent interaction with its corresponding dissipative counterpart; our method generalizes the basic structure used in the theory of ... More
Anomalous mass dimension of multi-flavor QCDOct 08 2016Models of strongly interacting theories with a large mass anomalous dimension ($\gamma_m$) provide an interesting possibility for the dynamical origin of the electroweak symmetry breaking. A laboratory for these models is QCD with many flavors, which ... More
A 125 GeV Scalar Boson and SU(N_{TC})\otimes SU(3)_{{}_{L}}\otimes U(1)_{{}_{X}} modelsMar 16 2013We verify that SU(N)_{{}_{TC}}\otimes SU(3)_{{}_{L}}\otimes U(1)_{{}_{X}} models, where the gauge symmetry breaking is totally dynamical and promoted by the non-Abelian technicolor (TC) group and the strong Abelian interactions, are quite constrained ... More
Mass and width of a composite Higgs bosonFeb 13 2009May 18 2009The scalar Higgs boson mass in a Technicolor model was obtained by Elias and Scadron with the analysis of an homogeneous Bethe-Salpeter equation (BSE), however it was performed before the most recent developments of walking gauge theories. It was not ... More
A dynamical mechanism to explain the top-bottom quark mass hierarchyAug 17 2004Jan 20 2005We discuss the mass splitting between the the top and bottom quarks in a technicolor scenario. The model proposed here contains a left-right electroweak gauge group. An extended technicolor group and mirror fermions are introduced. The top-bottom quark ... More
Entanglement swapping, light cones and elements of realityNov 06 2005Jul 20 2006Recently, a number of two-participant all-versus-nothing Bell experiments have been proposed. Here, we give local realistic explanations for these experiments. More precisely, we examine the scenario where a participant swaps his entanglement with two ... More
Jet radio emission in Cygnus X-1 and its orbital modulationOct 01 2006Dec 22 2006We present results of our detailed theoretical study of the observed orbital modulation of the radio emission in Cyg X-1. The modulation occurs due to free-free absorption in the wind from the companion star varying with the orbital phase, and our results ... More
Programming Realization of Symbolic Computations for Non-linear Commutator Superalgebras over the Heisenberg--Weyl Superalgebra: Data Structures and Processing MethodsMay 16 2009Aug 19 2009We suggest a programming realization of an algorithm for verifying a given set of algebraic relations in the form of a supercommutator multiplication table for the Verma module, which is constructed according to a generalized Cartan procedure for a quadratic ... More
Ambiguity-free formulation of the Higgs-Kibble modelOct 05 2010A renormalizable ambiguity-free formulation of the Higgs-Kibble model is proposed.
Quantum-Limited Amplification via Reservoir EngineeringNov 01 2013Apr 08 2014We describe a new kind of phase-preserving quantum amplifier which utilizes dissipative interactions in a parametrically-coupled three-mode bosonic system. The use of dissipative interactions provides a fundamental advantage over standard cavity-based ... More
Crossed Andreev reflection in diffusive contactsNov 06 2006Crossed Andreev reflection in multiterminal structures in the diffusive regime is addressed within the quasiclassical Keldysh-Usadel formalism. The elastic cotunneling and crossed Andreev reflection of quasiparticles give nonlocal currents and voltages ... More
Light composite scalar boson from a see-saw mechanism in two-scale TC modelsJun 25 2015We consider the possibility of a light composite scalar boson arising from mass mixing between a relatively light and heavy scalar singlets in a see-saw mechanism expected to occur in two-scale Technicolor (TC) models. A light composite scalar boson can ... More
Limit on the fermion masses in technicolor modelsAug 21 2003Recently it has been pointed out that no limits can be put on the scale of fermion mass generation $(M)$ in technicolor models, because the relation between the fermion masses $(m_f)$ and $M$ depends on the dimensionality of the interaction responsible ... More
Dynamical Symmetry Breaking in a Minimal 3-3-1 ModelOct 11 2012The gauge symmetry breaking in some versions of 3-3-1 models can be implemented dynamically because at the scale of a few TeVs the $U(1)_X$ coupling constant becomes strong. In this work we consider the dynamical symmetry breaking in a minimal $SU(3)_{{}_{TC}}\times ... More
Energy criterion to select the behavior of dynamical masses in technicolor modelsMay 05 2002We propose a quite general ansatz for the dynamical mass in technicolor models. We impose on this ansatz the condition for formation of the tightest composite boson state, or the criterion that it should lead to the deepest minimum of energy. This criterion ... More
Quantum corrections to energy of short spinning string in AdS5Jun 29 2008Feb 02 2009Motivated by desire to shed light on the strong coupling behaviour of anomalous dimensions of "short" gauge theory operators we consider the famous example of folded spinning string in AdS_5 in the limit of small semiclassical spin parameter \S = S/sqrt[lambda]. ... More
A statistical model of three-dimensional anisotropy and intermittency in strong Alfvénic turbulenceMay 24 2016We propose a simple statistical model of three-dimensionally anisotropic, intermittent, strong Alfv\'enic turbulence, incorporating both critical balance and dynamic alignment. Our model is based on log-Poisson statistics for Elsasser-field increments ... More
One- and many-body effects on mirages in quantum corralsAug 27 2002May 23 2003Recent interesting experiments used scanning tunneling microscopy to study systems involving Kondo impurities in quantum corrals assembled on Cu or noble metal surfaces. The solution of the two-dimensional one-particle Schrodinger equation in a hard wall ... More
New results for the missing quantum numbers labeling the quadrupole and octupole boson basisMay 24 2004Oct 27 2004The many $2^k$-pole boson states, $|N_kv_k\alpha_k I_kM_k>$ with $k=2,3$, realize the irreducible representation (IR) for the group reduction chains $SU(2k+1)\supset R_{2k+1}\supset R_3\supset R_2$. They have been analytically studied and widely used ... More
Technicolor models with coupled systems of Schwinger-Dyson equationsFeb 28 2019Mar 15 2019When Technicolor (TC), QCD, Extended Technicolor (ETC) and other interactions become coupled through their different Schwinger-Dyson equations, the solution of these equations are modified in comparison with the ones of the isolated equations. The change ... More
Curved space resolution of singularity of fractional D3-branes on conifoldNov 01 2001We construct a supergravity dual to the cascading $SU(N+M) x SU(N)$ supersymmetric gauge theory (related to fractional D3-branes on conifold according to Klebanov et al) in the case when the 3-space is compactified on $S^3$ and in the phase with unbroken ... More
Schwinger-Dyson approach and its application to generate a light composite scalarJan 15 2016Feb 24 2016We discuss the possibility of generating a light composite scalar boson, in a scenario that we may generically call Technicolor, or in any variation of a strongly interacting theory, where by light we mean a scalar composite mass about one order of magnitude ... More
Dynamical gluon mass corrections in heavy quarkonia decaysApr 26 2000Using the expression of the dynamical gluon mass obtained through the operator product expansion we discuss the relevance of gluon mass effects in the decays V -> hadrons (V = J/Psi, Upsilon). Relativistic and radiative corrections are also introduced ... More
Semiclassical rigid strings with two spins in AdS_5Nov 12 2009Semiclassical spinning string states in AdS_5 are, in general, characterised by the three SO(2,4) conserved charges: the energy E and the two spins S_1 and S_2. We discuss several examples of explicit classical solutions for rigid closed strings of (bended) ... More
Search for excited electrons through $γγ$ scatteringAug 10 2012We study the potential of $\gamma \gamma$ option of future high energy linear $e^{+}e^{-}$ colliders to search for excited electrons with spin-1/2. We calculate single production cross sections, give the angular distributions and $f-m^*$ contour plots ... More
A study of spectra of Cyg X-3 observed by BeppoSAXDec 22 2004Jan 10 2005We model the ~1-200 keV spectra of Cygnus X-3 observed by BeppoSAX. The continuum, modeled by Comptonization in a hybrid plasma, is modified by the strongly ionized plasma of the stellar wind of the Wolf-Rayet companion star. Discrete absorption and emission ... More
Quantum Corrections to Bekenstein-Hawking Black Hole Entropy and Gravity Partition FunctionsApr 25 2013Algebraic aspects of the computation of partition functions for quantum gravity and black holes in $AdS_3$ are discussed. We compute the sub-leading quantum corrections to the Bekenstein-Hawking entropy. It is shown that the quantum corrections to the ... More
Chiral expansion of nucleon PDF at $x\sim m_π/M_N$Nov 14 2013Based on the chiral perturbation theory, we investigate the low-energy dynamics of nucleon parton distributions. We show that in different regions of the momentum fraction $x$ the chiral expansion is significantly different. For nucleon parton distributions ... More
Effects of the stellar wind on X-ray spectra of Cygnus X-3Oct 30 2007Feb 04 2008We study X-ray spectra of Cyg X-3 from BeppoSAX, taking into account absorption and emission in the strong stellar wind of its companion. We find the intrinsic X-ray spectra are well modelled by disc blackbody emission, its upscattering by hot electrons ... More
On open superstring partition function in inhomogeneous rolling tachyon backgroundOct 27 2003Jan 27 2004We consider open superstring partition function Z on the disc in time-dependent tachyon background T= f(x_i) e^{m x_0} where the profile function f depends on spatial coordinates. We compute Z to second order in derivatives of f and compare the result ... More
On gravitational couplings in D-brane actionNov 12 2002Oct 26 2004We compute the two closed string graviton - two open string scalar scattering amplitude on the disc to show that there is no second-derivative curvature - scalar coupling term R X^2 in the low-energy effective action of a D-brane in curved space in type ... More
Coherent effects in double-barrier Josephson junctionsDec 07 1999The general solution for ballistic electronic transport through double-barrier Josephson junctions is derived. We show the existence of a regime of phase-coherent transport in which the supercurrent is proportional to the single barrier transparency and ... More
The origin of the first and third generation fermion masses in a technicolor scenarioFeb 19 2003Jan 22 2004We argue that the masses of the first and third fermionic generations, which are respectively of the order of a few MeV up to a hundred GeV, are originated in a dynamical symmetry breaking mechanism leading to masses of the order $\alpha \mu$, where $\alpha$ ... More
On (non)integrability of classical strings in p-brane backgroundsNov 15 2012Jan 07 2013We investigate the question of possible integrability of classical string motion in curved p-brane backgrounds. For example, the D3-brane metric interpolates between the flat and the AdS_5 x S^5 regions in which string propagation is integrable. We find ... More
On the power of non-local boxesApr 18 2005Nov 07 2005A non-local box is a virtual device that has the following property: given that Alice inputs a bit at her end of the device and that Bob does likewise, it produces two bits, one at Alice's end and one at Bob's end, such that the XOR of the outputs is ... More
Casimir effect for scalar fields under Robin boundary conditions on platesJul 31 2000Oct 22 2001We study the Casimir effect for scalar fields with general curvature coupling subject to mixed boundary conditions $(1+\beta_{m}n^{\mu}\partial_{\mu})\phi =0$ at $x=a_{m}$ on one ($m=1$) and two ($m=1,2$) parallel plates at a distance $a\equiv a_{2}-a_{1}$ ... More
Technicolor models with coupled systems of Schwinger-Dyson equationsFeb 28 2019When Technicolor (TC), QCD, Extended Technicolor (ETC) and other interactions become coupled through their different Schwinger-Dyson equations, the solution of these equations are modified in comparison with the ones of the isolated equations. The change ... More
A statistical model of three-dimensional anisotropy and intermittency in strong Alfvénic turbulenceMay 24 2016Dec 14 2016We propose a simple statistical model of three-dimensionally anisotropic, intermittent, strong Alfv\'enic turbulence, incorporating both critical balance and dynamic alignment. Our model is based on log-Poisson statistics for Elsasser-field increments ... More
Geodesics and admissible-path spaces in Carnot GroupsNov 26 2013We study the topology of admissible-loop spaces on a step-two Carnot group G. We use a Morse-Bott theory argument to study the structure and the number of geodesics on G connecting the origin with a 'vertical' point (geodesics are critical points of the ... More
Numerical analysis of renormalon technique in quantum mechanicsNov 29 1996Jul 14 1997We discuss the ways of extracting a low energy scale of an underlying theory using high energy scattering data. Within an exactly solvable model of quantum mechanics we analyze a technique based on introduction of nonperturbative power corrections accounting ... More
Analytical results for $e^+e^-\to t\bar t$ and $γγ\to t\bar t$ observables near the threshold up to the next-to-next-to-leading order of NRQCDApr 08 1999Oct 10 2001We present an analytical description of top-antitop pair production near the threshold in $e^+e^-$ annihilation and $\g\g$ collisions. A set of basic observables considered includes the total cross sections, forward-backward asymmetry and top quark polarization. ... More
Next-to-next-to-leading order relation between $R(e^+e^-\to b\bar b)$ and $Γ_{\rm sl}(b\to clν_l)$ and precise determination of $|V_{cb}|$May 16 1998Oct 30 1998We present the next-to-next-to-leading order relation between the moments of the $\Upsilon$ system spectral density and the inclusive $B$-meson semileptonic width. The perturbative series for the width as an explicit function of the moments is well convergent ... More
Quark-hadron duality for $K^0-\bar{K^0}$ mixingNov 27 1997Long distance contribution to the $K^0-\bar K^0$ mixing is taken into account consistently and the corrections to the naive duality result represented by the famous box diagram are found to be small. Estimates are given in the leading order of the chiral ... More
A scalar gluonium contribution to $K\rightarrowππ$ decayJul 17 1995We study a new $K\rightarrow\pi\pi$ decay channel with gluons in intermediate state which is normally neglected within the factorization framework. Both short-distance and long-distance parts of the amplitude are calculated. The chiral Lagrangian approach ... More
Periodic solutions of Schrodinger equation in Hilbert spaceSep 03 2012Necessary and sufficient conditions for existence of boundary value problem of Schrodinger equation are obtained in linear and nonlinear cases. Periodic analytical solutions are represented using generalized Green's operator
Bottom quark pole mass and $|V_{cb}|$ matrix element from $R(e^+e^-\to b\bar b)$ and $Γ_{sl}(b\to clν_l)$ in the next-to-next-to-leading orderJul 20 1998Mar 19 1999We present a consistent analysis of $\Upsilon$ sum rules and $B$-meson semileptonic width in the next-to-next-to-leading order in the strong coupling constant. The analysis is based on the analytical result for the heavy quark vector current correlator ... More
Practical techniques of QCD vs exact results of solvable modelsDec 30 1996Jul 14 1997We check quantitatively the validity of some popular phenomenological approaches of QCD in simple models. Dispersion sum rules are considered within the ladder approximation of a field-theoretic model with OPE given by ordinary loop diagrams which are ... More
Thin topological insulator film in a perpendicular magnetic fieldMar 10 2011May 10 2011We report on a study of an ultrathin topological insulator film with hybridization between the top and bottom surfaces, placed in a quantizing perpendicular magnetic field. We calculate the full Landau level spectrum of the film as a function of the applied ... More
Optimized perturbation theory for bound states: toy model and realistic problemJun 20 1995Within quantum mechanics model we study the problem of resummation of an asymptotic perturbation series for bound state parameters via optimization of the perturbative expansion. A possible application of the method to the positronium lifetime calculation ... More
Can Electro-Weak $\h$-Term be Observable ?May 14 1993We rederive and discuss the result of the previous paper that in the standard model $\theta$-term related to $W$-boson field can not be induced by weak instantons. This follows from the existence of the fermion zero mode in the instanton field even when ... More
Exact string background from a WZW model based on the Heisenberg groupMar 07 1994A WZW model for the non-semi-simple D-dimensional Heisenberg group, which directly generalizes the E_{2}^{c} group, is constructed. It is found to correspond to an D-dimensional string background of plane-wave type with physical Lorentz signature D-2. ... More
Notes on non-thermal X-ray radiation of radio supernova remnant W50 and collimated radiation of SS433Jun 19 2013Diffuse X-ray emission of the radio nebula W50 along the line of the of jets of the microquasar SS433 has a non-thermal power law component. This could be the inverse-Compton scattered emission of the SS433 accretion disk funnel, which is collimated in ... More
Next-to-next-to-leading order vacuum polarization function of heavy quark near threshold and sum rules for $b \bar b$ systemMar 16 1998Apr 06 1998A correlator of the vector current of a heavy quark is computed analytically near threshold in the next-to-next-to-leading order in perturbative and relativistic expansion that includes $\al_s^2$, $\al_sv$ and $v^2$ corrections in the coupling constant ... More
Comment on ``Next-to-next-to-leading order vacuum polarization function of heavy quark near threshold and sum rules for $b \bar b$ system'' and ``Next-to-next-to-leading order relation between $R(e^+e^-\to b\bar b)$ and $Γ_{\rm sl}(b\to clν_l)$ and precise ... MoreJan 19 1999The most recent recalculation of the two-loop correction to the static quark-antiquark potential gave the numerical value different from the previously known one. We comment on the effect this change produces on the numerical estimates of the bottom quark ... More
Extended analysis of the "penguin" part of $K\toππ$ amplitudeMar 14 1995We make an attempt to clarify the role of the annihilation or "penguin" mode in the description of the $K\rightarrow\pi\pi$ decay within the Standard Model. The attention is concentrated on new operators in the effective $\Delta S=1$ Hamiltonian and the ... More
A study of RXTE and BeppoSAX observations of Cyg X-3Jan 14 2004We present an analysis of Cyg X-3 data from RXTE/PCA,HEXTE and ASM, supplemented by a selected spectrum from BeppoSAX. We fit the PCA/HEXTE spectra from 1996-2000 by a model including hybrid Comptonization, reflection and absorption, and classify them ... More
Non-reciprocal quantum interactions and devices via autonomous feed-forwardOct 20 2016In a recent work [A. Metelmann and A. A. Clerk, Phys. Rev. X 5, 021025 (2015)], a general reservoir-engineering approach for generating non-reciprocal quantum interactions and devices was described. We show here how in many cases this general recipe can ... More
Deciphering the minimum of energy of some walking technicolor modelsMay 11 2010There are quasi-conformal theories, like the Minimal and Ultraminimal Technicolor models, which may break dynamically the gauge symmetry of the Standard Model and at the same time are compatible with electroweak precision data. The main characteristic ... More
Strength of the Trilinear Higgs Boson Coupling in Technicolor ModelsOct 14 2005Oct 20 2005We discuss the strength of the trilinear Higgs boson coupling in technicolor (or composite) models in a model independent way. The coupling is determined as a function of a very general ansatz for the technicolor self-energy, and turns out to be equal ... More
Scalar bosons in Minimal and Ultraminimal Technicolor: Masses, trilinear couplings and widthsDec 05 2009May 04 2010We compute masses, trilinear self-couplings and decay widths into weak bosons of the scalar composite bosons in the case of the Minimal and Ultraminimal technicolor models. The masses, computed via the Bethe-Salpeter equation, turn out to be light and ... More
Graph homology: Koszul and Verdier dualityFeb 12 2007We show that Verdier duality for certain sheaves on the moduli spaces of graphs associated to Koszul operads corresponds to Koszul duality of operads. This in particular gives a conceptual explanation of the appearance of graph cohomology of both the ... More
Top quark threshold production in $γγ$ collision in the next-to-leading orderOct 27 1998Apr 23 1999The total cross section of the top quark-antiquark pair production near threshold in $\gamma\gamma$ collision is computed analytically up to the next-to-leading order in perturbative and nonrelativistic expansion for general photon helicity. The approximation ... More
On a subtle point of sum rules calculations: toy modelMar 30 1995We consider a two-point correlator in massless $\phi^3$ model within the ladder approximation . The spectral density of the correlator is known explicitly and does not contain any resonances. Meanwhile making use of the standard sum rules technique with ... More
Topological response in Weyl semimetals and the chiral anomalyJun 08 2012Sep 25 2012We demonstrate that topological transport phenomena, characteristic of Weyl semimetals, namely the semi-quantized anomalous Hall effect and the chiral magnetic effect (equilibrium magnetic-field-driven current), may be thought of as two distinct manifestations ... More
Anomalous diffusion and quasistationarity in the HMF modelNov 12 2007We explore the quasistationary regime of the Hamiltonian Mean Field Model (HMF) showing that at least three different classes of events exist, with a different diffusive behavior and with a relative frequency which depends on the size of the system. Along ... More
Broadband polarization retarderApr 26 2011We derive a new kind of effective broadband polarization device using the analogy between the equation for the polarization of light, propagating through an optically anisotropic medium, and the optical Bloch equation in adiabatic regime, which describes ... More