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Operators for scattering of particles with spinOct 04 2016Operators for simulating the scattering of two particles with spin are constructed. Three methods are shown to give the consistent lattice operators for PN, PV, VN and NN scattering, where P, V and N denote pseudoscalar meson, vector meson and nucleon. ... More

A survey of top quark polarization at a polarized linear e^+ e^- colliderDec 21 2010Mar 25 2011We discuss in detail top quark polarization in above-threshold (t \bar t)-production at a polarized linear e^+ e^- collider. We pay particular attention to the minimization and maximization of the polarization of the top quark by tuning the longitudinal ... More

Single top quark polarization at O(alpha_s) in t t-bar production at a polarized linear e^+ e^- colliderSep 04 2012We present a detailed investigation of the NLO polarization of the top quark in t t-bar production at a polarized linear e^+ e^- collider with longitudinally polarized beams. By appropiately tuning the polarization of the beams one can achieve close to ... More

Reanalysis of lattice QCD spectra leading to the $D_{s0}^*(2317)$ and $D_{s1}^*(2460)$Dec 04 2014Jun 03 2015We perform a reanalysis of the energy levels obtained in a recent lattice QCD simulation, from where the existence of bound states of $KD$ and $KD^*$ are induced and identified with the narrow $D_{s0}^*(2317)$ and $D_{s1}^*(2460)$ resonances. The reanalysis ... More

Effects of staggered fermions and mixed actions on the scalar correlatorOct 14 2005We provide the analytic predictions for the flavor non-singlet scalar correlator, which will enable determination of the scalar meson mass from the lattice scalar correlator. We consider simulations with 2+1 staggered sea quarks and staggered or chiral ... More

Effects of partial quenching and staggered fermions on the scalar correlatorSep 22 2005Oct 20 2005We determine the mass of the lightest quark-antiquark scalar meson with I=1 using the simulation with two dynamical Domain Wall Fermions. The conventional exponential fit of the scalar correlator is justified in this case giving the mass 1.58 +/- 0.34 ... More

Quenched scalar meson correlator with Domain Wall FermionsSep 18 2002We study the singlet and non-singlet scalar-meson masses using domain wall fermions and the quenched approximation. The singlet mass is found to be smaller than the non-singlet mass and indicates that the lowest singlet meson state could be lighter than ... More

$c\to uγ$ in the minimal supersymmetric standard modelDec 11 2000The minimal supersymmetric standard model (MSSM) with universal soft breaking terms has a negligible effect on the rare $c\to u\gamma$ decay rate. We therefore study a general model with non-universal soft breaking terms constrained by vacuum stability ... More

Pseudo gap in the density of states in cupratesJan 21 2000In the framework of the t-J model for cuprates we analyze the development of a pseudo gap in the density of states (DOS), which at low doping starts to emerge for temperatures T<J and persists up to the optimum doping. The analysis is based on numerical ... More

Symmetries of spatial meson correlators in high temperature QCDFeb 08 2019Based on a complete set of $J = 0$ and $J=1$ spatial isovector correlation functions calculated with $N_F = 2$ domain wall fermions we identify an intermediate temperature regime of $T \sim 250 - 550$ MeV where chiral symmetry is restored but the correlators ... More

Can FCNC transition $c\to ul^+l^-$ be seen in $D\to Vl^+l^-$ decays?Jul 23 1998The decays $D\to Vl^+l^-$ present in principle the opportunity to observe the short distance FCNC transition $c\to ul^+l^-$, which is sensitive to the physics beyond the Standard Model. We analyze the $D \to V l^+ l^- $ decays within the Standard Model, ... More

FCNC transitions $c\to uγ$ and $s\to dγ$ in $B_c\to B_u^*γ$ and $B_s\to B_d^*γ$ decaysJan 08 1999Mar 23 1999We propose the $B_c\to B_u^*\gamma$ decay as the most suitable probe for the flavour changing neutral transition $c\to u\gamma$. We estimate the short and long distance contributions to this decay within the standard model and we find them to be comparable; ... More

Long distance contributions in $D \to V γ$ decaysJan 13 1998Oct 21 1998Using the factorization scheme for the nonleptonic $D \to V V_0$ weak amplitudes, we classify all diagrams which arise in $D \to V \gamma$ decays and calculate them with the help of the hybrid model which combines the heavy quark effective theory and ... More

Resonant and nonresonant contributions to the weak $D\to Vl^+l^-$ decaysMay 26 1998Oct 22 1998The Cabibbo suppressed decays $D\to Vl^+l^-$ (V is light vector meson) present in principle the opportunity to observe the short distance FCNC transition $c\to ul^+l^-$, which is sensitive to physics beyond the Standard Model. We analyze these as well ... More

Probing $c\to uγ$ in $B_c\to B_u^*γ$ decayMay 11 1999Flavour changing neutral current (FCNC) transitions $c\to u\gamma$ and $c\to ul^+l^-$ are very rare in the standard model and present an interesting probe for the physics beyond it. We study long distance contamination to these short distance processes ... More

FCNC transition $c\to uγ$ in $B_c\to B_u^*γ$ decayNov 17 1999We propose the $B_c\to B_u^*\gamma$ decay as the most suitable probe for the flavour changing neutral transition $c\to u\gamma$. We estimate the short and long distance contributions to this decay within the standard model and we find them to be comparable; ... More

Rare charm meson decays D->Pl^+l^- and c->ul^+l^- in SM and MSSMJun 28 2001We study the nine possible rare charm meson decays D->Pl^+l^- (P=pi,K,eta,eta') using the Heavy Meson Chiral Lagrangians and find them to be dominated by the long distance contributions. The decay D^+ -> pi^+l^+l^- with the branching ratio 1*10^(-6) is ... More

Radiative decays of D mesonsAug 20 1998Oct 16 1998The short-distance contribution due to the $c\to u\gamma$ penguin as well as long-distance contributions are considered in an analysis of $D\to V\gamma$ decays, the latter being dominant. The matrix elements for nine $D\to V\gamma$ transitions are calculated ... More

$B_sπ^+$ scattering and search for X(5568) with lattice QCDJul 11 2016We investigate $B_s\pi^+$ scattering in s-wave using lattice QCD in order to search for an exotic resonance X(5568) with flavor $\bar b s \bar d u$; such a state was recently reported by D0 but was not seen by LHCb. If X(5568) with $J^P=0^+$ exists, it ... More

$B_sπ^+$ scattering and search for X(5568) with lattice QCDJul 11 2016Oct 11 2016We investigate $B_s\pi^+$ scattering in s-wave using lattice QCD in order to search for an exotic resonance X(5568) with flavor $\bar b s \bar d u$; such a state was recently reported by D0 but was not seen by LHCb. If X(5568) with $J^P=0^+$ exists, it ... More

Scattering phase shift and resonance properties on the lattice: an introductionOct 20 2011We describe the method for extracting the elastic scattering phase shift from a lattice simulation at an introductory level, for non-lattice practitioners. We consider the scattering in a resonant channel, where the resulting phase shift delta(s) allows ... More

Thermodynamic and thermoelectric properties of high-temperature cuprate superconductors in the stripe phaseNov 01 2002May 06 2003We examine the thermodynamic and thermoelectric properties in the stripe phase of high-Tc cuprates, by using the finite-temperature Lanczos technique for the t-J model with a potential that stabilizes vertical charge stripes. When the stripe potential ... More

Vanishing Hall Constant in the Stripe Phase of CupratesFeb 22 2001The Hall constant R_H is considered for the stripe structures. In order to explain the vanishing of R_H in LNSCO at x = 1/8, we use the relation of R_H to the Drude weight D as well as direct numerical calculation, to obtain results within the t-J model, ... More

Lattice operators for scattering of particles with spinJul 22 2016We construct operators for simulating the scattering of two hadrons with spin on the lattice. Three methods are shown to give the consistent operators for PN, PV, VN and NN scattering, where P, V and N denote pseudoscalar, vector and nucleon. Explicit ... More

X(3872) and Y(4140) using diquark-antidiquark operators with lattice QCDOct 30 2015We discuss a recent lattice study of charmonium-like mesons with $J^{PC}=1^{++}$ and three quark contents $\bar cc\bar du$, $\bar cc(\bar uu + \bar dd)$ and $\bar cc\bar ss$, where the latter two can mix with $\bar cc$. In this quantum channel, the long ... More

The rare decays of D mesonsAug 22 2002The flavor changing transitions in the c->u gamma, c->u gamma gamma and c->u l+ l- offer the possibility to search for new physics in the charm sector. We investigate dominant decay mechanisms in the radiative decays D->V gamma, D->P(V) l+ l-, D->gamma ... More

A Possible Arena for Searching New Physics - the $Γ(D^0 \to ρ^0 γ)/Γ(D^0 \to ωγ)$ RatioJun 06 2000We propose to investigate flavour changing neutral currents in the $c \to u \gamma$ transition through the measurement of the difference between $\Gamma (D^0 \to \rho^0 \gamma)$ and $\Gamma (D^0 \to \omega \gamma)$. This is based on the observation that ... More

Taste breaking effects in scalar meson correlatorsOct 03 2006As a consistency check of the staggered-fermion fourth-root approximation, we analyze the a_0 and f_0 correlators, including the effects of two-meson taste-multiplet intermediate states. Rooted staggered chiral perturbation theory describes the contributions ... More

Incoherent transport induced by a single static impurity in a Heisenberg chainJan 28 2009The effect of a single static impurity on the many-body states and on the spin and thermal transport in the one-dimensional anisotropic Heisenberg chain at finite temperatures is studied. Whereas the pure Heisenberg model reveals Poisson level statistics ... More

Decay of rho and a1 mesons on the lattice using distillationNov 02 2011We extract the P-wave pi-pi phase shift for five values of pion relative momenta, which gives information on the rho resonance. The Breit-Wigner formula describes the pi-pi phase shift dependence nicely and we extract m(rho)=792(7)(8) MeV and the coupling ... More

Anomalous scaling of conductivity in integrable fermion systemsMar 12 2004Jun 23 2004We analyze the high-temperature conductivity in one-dimensional integrable models of interacting fermions: the t-V model (anisotropic Heisenberg spin chain) and the Hubbard model, at half-filling in the regime corresponding to insulating ground state. ... More

Scalar meson in dynamical and partially quenched two-flavor QCD: lattice results and chiral loopsJul 29 2004This is an exploratory study of the lightest non-singlet scalar $q\bar q$ state on the lattice with two dynamical quarks. Domain Wall fermions are used for both sea and valence quarks on a 16^3*32 lattice with an inverse lattice spacing of 1.7 GeV. We ... More

Top Quark Production at TeV Energies as a Potential SUSY DetectorApr 24 2001We consider the process of top-antitop production from electron-positron annihilation, for c. m. energies in the few TeV regime, in the MSSM theoretical framework. We show that, at the one loop level, the \underline{slopes} of a number of observable quantities ... More

Pion-nucleon scattering in the Roper channel from lattice QCDOct 05 2016We present a lattice QCD study of $N\pi$ scattering in the positive-parity nucleon channel, where the puzzling Roper resonance $N^*(1440)$ resides in experiment. The study is based on the PACS-CS ensemble of gauge configurations with $N_f=2+1$ Wilson-clover ... More

Lattice studies of charmonia and exoticsAug 28 2015The lattice QCD simulations of charmonia and exotic charmonium-like states are reviewed. I report on the first exploratory simulation of charmonium resonances above open charm threshold which takes into account the strong decay. The puzzles related to ... More

A lattice study of light scalar tetraquarks with isopins 0, 1/2 and 1Sep 30 2008The observed mass pattern of scalar resonances below 1 GeV gives preference to the tetraquark assignment over the conventional $\bar qq$ assignment for these states. We present a search for tetraquarks with isospins 0,1/2,1 in lattice QCD, where isospin ... More

Scalar mesons on the LatticeNov 09 2005The simulations of the light scalar mesons on the lattice are presented at the introductory level. The methods for determining the scalar meson masses are described. The problems related to some of these methods are presented and their solutions discussed. ... More

Hadron SpectroscopyNov 03 2014Recent results on the hadron spectroscopy from lattice QCD are reviewed with emphasis on the meson sector and in particular on quarkonium-like $XYZ$ states. I report on the first rigorous treatment of the near-threshold states $X(3872)$ and $D_s^0(2317)$, ... More

Electron Green's Function in the Planar t-J ModelNov 29 1996The electron Green's functions $G({\bf k},\omega)$ within the t-J model and in the regime of intermediate doping is studied analytically using equations of motion for projected fermionic operators and the decoupling of the self energy into the single-particle ... More

Hall effect of charge carriers in a correlated systemSep 30 1996The dynamical Hall response in a correlated electronic system is analysed within the linear response theory for tight binding models. At $T=0$ the d.c. Hall constant for a single quasiparticle is expressed explicitly via the charge stiffness, and a semiclassical ... More

Hadron spectroscopy and interactions from lattice QCDSep 10 2016Sep 23 2016Lattice QCD approach to study the hadronic resonances and exotic hadrons is described at an introductory level. The main challenge is that these states decay strongly via one or more decay channels, and they often lie near thersholds. Specific results ... More

Lattice searches for tetraquarks and mesonic molecules: light scalar mesons and XYZ statesApr 21 2010Searches for tetraquarks and mesonic molecules in lattice QCD are briefly reviewed. In the light quark sector the most serious candidates are the lightest scalar resonances sigma, kappa, a0 and f0. In the hidden-charm sector I discuss lattice simulations ... More

Lattice QCD review of charmonium and open-charm spectroscopyOct 16 2013Oct 18 2013Lattice QCD results on the spectroscopy of charmonium(like) states and open charm mesons are reviewed. Near-threshold states X(3872) and D_{s0}^*(2317) were treated rigorously for the first time and the searches for Z_c^+(3900), X(4140) and $cc\bar u\bar ... More

Simulations of light scalar mesons on the lattice and related difficultiesApr 16 2008I review the lattice simulations of light scalar mesons with quark-antiquark and tetraquark interpolating fields. Several difficulties which complicate the extraction of scalar meson masses from the scalar correlators are pointed out. One of the major ... More

Normal State Properties of Cuprates: t-J Model vs. ExperimentJul 03 2000We discuss some recent results for the properties of doped antiferromagnets, obtained within the planar t-J model mainly by the finite-temperature Lanczos method, with the emphasis on the comparison with experimental results in cuprates. Among the thermodynamic ... More

On the universal optical conductivity and single-particle relaxation in cupratesMay 19 2000Jul 14 2000The origin of the universal optical conductivity form sigma(omega) ~ (1-e^(omega/T))/omega established in numerical model studies of doped antiferromagnets and consistent with experiments on cuprates near optimal doping is discussed. It is shown that ... More

Probing new physics in rare charm processesApr 17 2001We explore the sensitivity of the flavour changing neutral currents among c and u quarks in the context of the Minimal Supersymmetric Standard Model. The standard model rate for c->u gamma can be enhanced by up to two orders of magnitudes in general MSSM, ... More

Exotic and conventional mesons from latticeSep 28 2014Recent results on meson spectroscopy from lattice QCD are reviewed. The emphasis is on interesting states near thresholds like $Z_c^+(3900)$, $X(3872)$ and $D_{s0}^*(2317)$. Another focus is on the meson resonances in light, strange and charm sector, ... More

Weak decays of Heavy mesonsOct 11 2000I explore the possibility of using heavy meson decays as probes for flavour changing neutral transitions (FCNC) $c\to u\gamma$ and $c\to ul^+l^-$. In the standard model, these are the most frequent FCN transitions among the quarks with charge $2/3e_0$. ... More

Signal for CP violation in $B^{\pm} \to P {\bar P} π^{\pm}$ decaysJul 21 1998We analyze the partial rate asymmetry in $B^{\pm} \to P {\bar P} \pi^{\pm}$ decays ($ P = \pi^+, K ^+, \pi^0, \eta$) which results from the interference of the nonresonant decay amplitude and the resonant amplitude for $B^{\pm} \to \chi_{c0} \pi^{\pm} ... More

The CP violating asymmetry in $B^{\pm} \to M {\bar M} π^{\pm}$ decaysSep 04 1998We analyze the asymmetry in the partial widths for the decays $B^{\pm} \to M {\bar M} \pi^{\pm}$ ($ M = \pi^+, K ^+, \pi^0, \eta$), which results from the interference of the nonresonant decay amplitude with the resonant amplitude for $B^{\pm} \to \chi_{c0} ... More

Lattice study of light scalar tetraquarks with I=0,2,1/2,3/2: are sigma and kappa tetraquarks?May 06 2010Nov 26 2010We investigate whether the lightest scalar mesons sigma and kappa have a large tetraquark component, as is strongly supported by many phenomenological studies. A search for possible light tetraquark states with J^PC=0^++ and I=0, 2, 1/2, 3/2 on the lattice ... More

Searching for tetraquarks on the latticeFeb 01 2010We address the question whether the lightest scalar mesons sigma and kappa are tetraquarks. We present a search for possible light tetraquark states with J^PC=0^++ and I=0, 1/2, 3/2, 2 in the dynamical and the quenched lattice simulations using tetraquark ... More

Spectroscopy of light tetraquark statesOct 15 2009We address the question whether the lightest scalar mesons sigma and kappa are tetraquarks, as is strongly supported by many phenomenological studies. We present a search for possible light tetraquark states with J^PC=0^++ and I=0, 1/2, 3/2, 2 on the ... More

Hadronic Resonances in Lattice QCDApr 08 2013I discuss how masses and widths of hadron resonances are extracted from lattice QCD. Recent lattice results on the light, strange and charm meson resonances are reviewed. Their properties are revealed by simulating the corresponding scattering channels ... More

Finite Temperature Dynamical Correlations using the Microcanonical Ensemble and the Lanczos AlgorithmFeb 11 2003We show how to generalise the zero temperature Lanczos method for calculating dynamical correlation functions to finite temperatures. The key is the microcanonical ensemble, which allows us to replace the involved canonical ensemble with a single appropriately ... More

Ground State and Finite Temperature Lanczos MethodsNov 25 2011The present review will focus on recent development of exact-diagonali- zation (ED) methods that use Lanczos algorithm to transform large sparse matrices onto the tridiagonal form. We begin with a review of basic principles of the Lanczos method for computing ... More

Universal Charge and Spin Response in Optimally Doped AntiferromagnetsJul 11 1995Charge and spin response in the planar $t-J$ model at finite temperatures are investigated numerically, in the regime corresponding to cuprates at intermediate doping. We show that the local spin correlation function is $T$-independent, leading to $\chi''(\omega<J) ... More

Universality of Charge and Spin Response in Doped AntiferromagnetsJan 18 1996Recent results for the finite-temperature static and dynamical properties of the planar $t-J$ model, obtained by a novel numerical method for small correlated systems, are reviewed. Of particular interest are $T>0$ charge and spin response functions: ... More

Evidence for ideal insulating/conducting state in a 1D integrable systemAug 18 1995Using numerical diagonalization techniques we analyze the finite temperature/frequency conductance of a one dimensional model of interacting spinless fermions. Depending on the interaction, the observed finite temperature charge stiffness and low frequency ... More

Search for Z_c^+(3900) in the 1^+- channel on the latticeAug 09 2013Oct 16 2013Recently three experiments reported a discovery of manifestly exotic Z_c^+(3900) in the decay to J/psi pi+, while J and P are experimentally unknown. We search for this state on the lattice by simulating the channel with J^PC=1^+- and I=1, and we do not ... More

Effects of Littlest Higgs model in rare D meson decaysNov 04 2005Feb 23 2006A tree-level flavor changing neutral current in the up-like quark sector appears in one of the variations of the Littlest Higgs model. We investigate the effects of this coupling in the D+ -> pi+ l+ l- and D0 -> rho0 l+ l- decays, which are the most appropriate ... More

Pseudogap and the Fermi surface in the t-J modelSep 12 2001We calculate spectral functions within the t-J model as relevant to cuprates in the regime from low to optimum doping. On the basis of equations of motion for projected operators an effective spin-fermion coupling is derived. The self energy due to short-wavelength ... More

Spectral functions and pseudogap in the t-J modelNov 06 2000Feb 28 2001We calculate spectral functions within the t-J model as relevant to cuprates in the regime from low to optimum doping. On the basis of equations of motion for projected operators an effective spin-fermion coupling is derived. The self energy due to short-wavelength ... More

Nonlinear current response of an isolated system of interacting fermionsJul 20 2010Nonlinear real-time response of interacting particles is studied on the example of a one-dimensional tight-binding model of spinless fermions driven by electric field. Using equations of motion and numerical methods we show that for a non-integrable case ... More

Search for New Physics in Rare D DecaysOct 03 2006In many extensions of the standard model an additional up-like heavy quark appears. Its appearance induces flavour changing neutral current transition in the up-quark region at the tree level. We investigate possible effects of these models in the c->u ... More

Reply to the Comments by B. Farid and A.M. Tsvelik, arXiv:0909.2886v1, and B. Farid, arXiv:0909.2887v1Feb 19 2010In the recent preprints the authors claim that conclusions on the violation of the Luttinger sum rule (LSR) as put forward in published papers by the present authors are false or at least not conclusive enough. It concerns the validity of the LSR within ... More

Finite-temperature dynamics with the density-matrix renormalization group methodSep 01 2009Oct 22 2009We present a novel numerical method for the evaluation of dynamical response functions at finite temperatures in one-dimensional strongly correlated systems. The approach is based on the density-matrix renormalization group method, combined with the finite-temperature ... More

Breakdown of the Luttinger sum rule within the Mott-Hubbard insulatorMar 31 2008Oct 10 2008The validity of the Luttinger sum rule is investigated within the prototype tight-binding model of interacting fermions in one dimension, i.e., the t-V model including the next-nearest neighbor hopping t' in order to break the particle-hole symmetry. ... More

Luttinger sum rule for finite systems of correlated electronsSep 12 2006Nov 28 2006The validity of the Luttinger sum rule is considered for finite systems of interacting electrons, where the Fermi volume is determined by location of zeroes of Green's function. It is shown that the sum rule in the paramagnetic state is evidently violated ... More

Magnetic collective mode in underdoped cuprates: a phenomenological analysisJul 13 2006Oct 24 2006The dynamical spin susceptibility as relevant for underdoped cuprates is analysed within the memory-function (MeF) approach. A phenomenological damping function combined with a $T$-independent sum rule is used to describe the anomalous normal state and ... More

Anomalous Spin Dynamics in Doped Quantum AntiferromagnetsOct 24 1994Finite-temperature spin dynamics in planar t-J model is studied using the method based on the Lanczos diagonalization of small systems. Dynamical spin structure factor at moderate dopings shows the coexistence of free-fermion-like and spin-fluctuation ... More

Reactive Hall constant of Strongly Correlated ElectronsJul 12 2001The zero-temperature Hall response within tight-binding models of correlated electrons is studied. Using the linear response theory and a linearization in the magnetic field B, a general relation for the reactive (zero frequency) Hall constant in the ... More

Spectral properties of the planar t-J modelJul 19 1996The single-particle spectral functions $A({\bf k},\omega)$ and self-energies $\Sigma({\bf k},\omega)$ are calculated within the $t-J$ model using the finite-temperature Lanczos method for small systems. A remarkable asymmetry between the electron and ... More

Charge Dynamics in the Planar t-J ModelDec 28 1994The finite-temperature optical conductivity $\sigma(\omega)$ in the planar $t-J$ model is analysed using recently introduced numerical method based on the Lanczos diagonalization of small systems (up to 20 sites), as well as by analytical approaches, ... More

Spin-fluctuation mechanism of superconductivityJun 28 2005Normal and superconducting state spectral properties of cuprates are theoretically described within the extended t-J model. The method is based on the equations of motion for projected fermionic operators and the mode-coupling approximation for the self-energy ... More

Freezing of spin dynamics in underdoped cupratesFeb 03 2009The Mori's memory function approach to spin dynamics in doped antiferromagnetic insulator combined with the assumption of temperature independent static spin correlations and constant collective mode damping leads to w/T scaling in a broad range. The ... More

Transport of Strongly Correlated ElectronsMar 14 2002Lectures deal with the theory of electronic transport, in particular with the electrical conductivity, in systems dominated by strong electron-electron repulsion. The concept of charge stiffness is introduced to distinguish conductors and insulators at ... More

On the electron-energy loss spectra and plasmon resonance in cupratesMar 18 1999The consequences of the non-Drude charge response in the normal state of cuprates and the effect of the layered structure on electron-energy loss spectra are investigated, both for experiments in the transmission and the reflection mode. It is shown that ... More

Spectral functions, Fermi surface and pseudogap in the t-J modelSep 12 2001Spectral functions within the generalized t-J model as relevant to cuprates are analyzed using the method of equations of motion for projected fermion operators. In the evaluation of the self energy the decoupling of spin and single-particle fluctuations ... More

A lattice study of light scalar tetraquarksOct 09 2008The observed mass pattern of scalar resonances below 1 GeV gives preference to the tetraquark assignment over the conventional $\bar qq$ assignment for these states. We present a search for tetraquarks with isospins 0, 1/2, 1 in lattice QCD, where the ... More

Violation of the Luttinger sum rule within the Hubbard model on a triangular latticeSep 03 2007Jul 11 2008The frequency-moment expansion method is developed to analyze the validity of the Luttinger sum rule within the Mott-Hubbard insulator, as represented by the generalized Hubbard model at half filling and large $U$. For the particular case of the Hubbard ... More

Freezing of spin dynamics and omega/T scaling in underdoped cupratesJan 06 2010The memory function approach to spin dynamics in doped antiferromagnetic insulator combined with the assumption of temperature independent static spin correlations and constant collective mode damping leads to omega/T scaling in a broad range. The theory ... More

Transport in one dimensional quantum systemsApr 28 2003May 05 2003In this Chapter, we present recent theoretical developments on the finite temperature transport of one dimensional electronic and magnetic quantum systems as described by a variety of prototype models. In particular, we discuss the unconventional transport ... More

Temperature Dependence of Hall Response in Doped AntiferromagnetsMar 25 2002Using finite-temperature Lanczos method the frequency-dependent Hall response is calculated numerically for the t-J model on the square lattice and on ladders. At low doping, both the high-frequency RH* and the d.c. Hall coefficient RH0 follow qualitatively ... More

Finite-temperature properties of doped antiferromagnetsMar 26 1998We review recent results for the properties of doped antiferromagnets, obtained by the numerical analysis of the planar t-J model using the novel finite-temperature Lanczos method for small correlated systems. First we shortly summarize our present understanding ... More

Raman Response in Doped AntiferromagnetsJan 29 1996Mar 07 1996The resonant part of the $B_{1g}$ electronic Raman scattering response is calculated within the $t-J$ model on a planar lattice as a function of temperature and hole doping, using a finite-temperature diagonalization method for small systems. Results, ... More

Anomalous normal-state properties of iron pnictides: phenomenological theoryDec 16 2009Mar 01 2010We employ the phenomenological theory of the quasiparticle relaxation based on the simplified two-band description and the spin-fluctuation induced interband coupling to analyze recent normal-state transport data in electron-doped iron pnictides, in particular ... More

Double dispersion of the magnetic resonant mode in cupratesMar 04 2005The magnetic excitation spectra in the vicinity of the resonant peak, as observed by inelastic neutron scattering in cuprates, are studied within the memory-function approach. It is shown that at intermediate doping the superconducting gap induces a double ... More

Magnetic response of nonmagnetic impurities in cupratesJun 04 2004A theory of the local magnetic response of a nonmagnetic impurity in a doped antiferromagnet, as relevant to the normal state in cuprates, is presented. It is based on the assumption of the overdamped collective mode in the bulk system and on the evidence, ... More

Thermodynamics of the planar Hubbard modelJun 04 2002The thermodynamic properties: specific heat, entropy, spin susceptibility $\chi_s$ and charge susceptibility $\chi_c$ are studied as a function of temperature and doping within the two-dimensional Hubbard model with various $U/t=4 - 12$. Quantities are ... More

Thermodynamic properties of the planar $t-J$ modelMar 12 1996Several thermodynamic quantities within the planar $t-J$ model are calculated using the $T>0$ Lanczos method on clusters of up to 26 sites. Hole density $c_h(\mu,T)$ shows a non-Fermi liquid behavior as a function of $T$ and suggests a transition from ... More

Spectral Functions and Pseudogap in Models of Strongly Correlated ElectronsAug 30 2002The theoretical investigation of spectral functions and pseudogap in systems with strongly correlated electrons is discussed, with the emphasis on the single-band t-J model as relevant for superconducting cuprates. The evidence for the pseudogap features ... More

Spin-fluctuation mechanism of superconductivity in cupratesFeb 02 2005The theory of superconductivity within the t-J model, as relevant for cuprates, is developed. It is based on the equations of motion for projected fermionic operators and the mode-coupling approximation for the self-energy matrix. The dynamical spin susceptibility ... More

Evidence for X(3872) from DD* scattering on the latticeJul 19 2013Oct 16 2013A candidate for the charmonium(like) state X(3872) is found 11 +/- 7 MeV below the DD* threshold using dynamical Nf=2 lattice simulation with J^PC=1^++ and I=0. This is the first lattice simulation that establishes a candidate for X(3872) in addition ... More

Scattering phase shifts for two particles of different mass and non-zero total momentum in lattice QCDFeb 09 2012May 15 2012We derive the relation between the scattering phase shift and the two-particle energy in the finite box, which is relevant for extracting the strong phase shifts in lattice QCD. We consider elastic scattering of two particles with different mass and with ... More

Dynamical central peak and spinon deconfinement in frustrated spin chainsMar 22 2010Studying the dynamical spin structure factor in frustrated spin chains with spontaneously dimerized ground state we show that besides the gapped spin-wave excitations there appears at finite temperatures also a sharp central peak. The latter can be attributed ... More

Resistivity and optical conductivity of cuprates within the t-J modelApr 25 2005Jun 08 2005The optical conductivity $\sigma(\omega)$ and the d.c. resistivity $\rho(T)$ within the extended t-J model on a square lattice, as relevant to high-$T_c$ cuprates, are reinvestigated using the exact-diagonalization method for small systems, improved by ... More

Thermoelectric power in one-dimensional Hubbard modelJul 09 2004The thermoelectric power S is studied within the one-dimensional Hubbard model using the linear response theory and the numerical exact-diagonalization method for small systems. While both the diagonal and off-diagonal dynamical correlation functions ... More

Momentum dependent relaxation rate and pseudogap in doped magnetic insulatorsAug 14 2006The spectral functions and corresponding self energies are calculated within the planar t-t'-J model as relevant to hole-doped cuprates using the exact diagonalization method at finite temperatures, combined with the averaging over twisted boundary conditions. ... More