Search results for "lattice [space-time]"
showing 10 items of 692 documents
Ds0⁎±(2317)and KD scattering fromBs0decay
2015
We study the B¯s0→Ds−(KD)+ weak decay, and look at the KD invariant mass distribution, for which we use recent lattice QCD results for the KD interaction from where the Ds0⁎(2317) resonance appears as a KD bound state. Since there are not yet experimental data on this reaction, in a second step we propose an analysis method to obtain information on the Ds0⁎(2317) resonance from the future experimental KD mass distribution in this decay. For this purpose, we generate synthetic data taking a few points from our theoretical distribution, to which we add a 5% or 10% error. With this analysis method, we prove that one can obtain from these “data” the existence of a bound KD state, the KD scatter…
First-Principles Calculation of Electroweak Box Diagrams from Lattice QCD.
2020
We present the first realistic lattice QCD calculation of the $\gamma W$-box diagrams relevant for beta decays. The nonperturbative low-momentum integral of the $\gamma W$ loop is calculated using a lattice QCD simulation, complemented by the perturbative QCD result at high momenta. Using the pion semileptonic decay as an example, we demonstrate the feasibility of the method. By using domain wall fermions at the physical pion mass with multiple lattice spacings and volumes, we obtain the axial $\gamma W$-box correction to the semileptonic pion decay, $\Box_{\gamma W}^{VA}\big|_{\pi}=2.830(11)_{\mathrm{stat}}(26)_{\mathrm{sys}}\times10^{-3}$, with the total uncertainty controlled at the leve…
Study of dynamics ofD0→K−e+νeandD0→π−e+νedecays
2015
In an analysis of a 2.92 fb(-1) data sample taken at 3.773 GeV with the BESIII detector operated at the BEPCII collider, we measure the absolute decay branching fractions B(D-0 -> K(-)e(+)nu(e)) = (3.505 +/- 0.014 +/- 0.033)% and B(D-0 -> pi(-)e(+)nu(e)) = (0.295 +/- 0.004 +/- 0.003)%. From a study of the differential decay rates we obtain the products of hadronic form factor and the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element f(+)(K)(0)vertical bar V-cs vertical bar = 0.7172 +/- 0.0025 +/- 0.0035 and f(+)(pi)(0)vertical bar V-cd vertical bar = 0.1435 +/- 0.0018 +/- 0.0009. Combining these products with the values of vertical bar V-cs(d)vertical bar from the SM constrain…
‘‘Improved’’ lattice study of semileptonic decays ofDmesons
1995
We present results of a lattice computation of the matrix elements of the vector and axial-vector currents which are relevant for the semi-leptonic decays $D \rightarrow K$ and $D \rightarrow K^*$. The computations are performed in the quenched approximation to lattice QCD on a $24^3 \times 48$ lattice at $\beta=6.2$, using an $O(a)$-improved fermionic action. In the limit of zero lepton masses the semi-leptonic decays $D \rightarrow K$ and $D \rightarrow K^*$ are described by four form factors: $f^{+}_K,V,A_1$ and $A_2$, which are functions of $q^2$, where $q^{\mu}$ is the four-momentum transferred in the process. Our results for these form factors at $q^2=0$ are: $f^+_K(0)=0.67 \er{7}{8}$…
Theory of the growth mode for a thin metallic film on an insulating substrate
2002
We have developed a novel theory predicting the growth mode of a thin metallic film on an insulating substrate. This combines ab initio electronic structure calculations for several ordered metal/insulator interfaces (varying both coverage and substrate lattice constant), with a thermodynamic approach based on microscopic calculations. We illustrate this approach for Ag film deposited on MgO(0 0 1) substrate. Ab initio calculations predict high mobility of adsorbed silver atoms on the perfect magnesia surface even at low temperatures. Our theoretical analysis clearly demonstrates that the growth of metallic islands is predominant at the initial stage of silver deposition, which agrees with …
Site symmetry approach applied to the supercell model of MgAl2O4 spinel with oxygen interstitials: Ab initio calculations
2018
This study has been carried out within the framework of the EUROfusion Consortium and has been provided funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The authors are indebted to E.A. Kotomin, A.I. Popov and R. Vila for stimulating discussions. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Calculations have been performed using both the Marconi supercomputer system at the Computational Simulation Centre (Italy) and the Computer Center of St. Petersburg State University.
2D Slab Models of Nanotubes Based on Tetragonal TiO2 Structures: Validation over a Diameter Range
2021
This research was funded by the M-ERA.NET project ?Multiscale computer modelling, synthesis and rational design of photo(electro)catalysts for efficient visible-light-driven seawater splitting? (CatWatSplit). Institute of Solid State Physics, University of Latvia as the Center of Excel-lence has received funding from the European Union?s Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under Grant Agreement No. 739508, project CAMART2.
Special factors and the combinatorics of suffix and factor automata
2011
AbstractThe suffix automaton (resp. factor automaton) of a finite word w is the minimal deterministic automaton recognizing the set of suffixes (resp. factors) of w. We study the relationships between the structure of the suffix and factor automata and classical combinatorial parameters related to the special factors of w. We derive formulae for the number of states of these automata. We also characterize the languages LSA and LFA of words having respectively suffix automaton and factor automaton with the minimal possible number of states.
Binding Sites, Vibrations and Spin-Lattice Relaxation Times in Europium(II)-Based Metallofullerene Spin Qubits.
2021
Abstract To design molecular spin qubits with enhanced quantum coherence, a control of the coupling between the local vibrations and the spin states is crucial, which could be realized in principle by engineering molecular structures via coordination chemistry. To this end, understanding the underlying structural factors that govern the spin relaxation is a central topic. Here, we report the investigation of the spin dynamics in a series of chemically designed europium(II)‐based endohedral metallofullerenes (EMFs). By introducing a unique structural difference, i. e. metal‐cage binding site, while keeping other molecular parameters constant between different complexes, these manifest the ke…
Monte Carlo studies of polymer interdiffusion and spinodal decomposition: A review
1991
Abstract Putting a layer of polymer A on top of a layer of polymer B, the broadening of the interfacial profile is observed in the framework of a lattice model (‘bond fluctuation method’). The interdiffusion constant is studied as a function of chain length, vacancy concentration, and interaction energy between unlike monomers, and a comparison with pertinent theoretical predictions is made. A lattice model where polymers are represented as self-avoiding walks on a simple cubic lattice is used to model ‘spinodal decomposition’, i.e. phase separation by ‘uphill diffusion’ in the unstable part of the phase diagram of a polymer mixture. For chain lengths N ≤ 32, the linearized Cahn-like theory…