Search results for "imaginary"
showing 10 items of 86 documents
A critical analysis on deeply bound kaonic states in nuclei
2005
We make a critical analysis on the theoretical calculations that lead to predictions of deeply bound kaonic states in nuclei. The model set-up, after dropping several important processes and channels, leads unavoidably to an unrealistic deep potential with a very small imaginary part. We review also the experimental results taken as reference for the claim of deeply bound kaons. We suggest that the peaks of the proton spectra come from $K^-$ absorption on a pair of nucleons, leaving the rest of the nucleons as spectators. Based on this conjecture we predict what would happen in other nuclei.
Accessing the real part of the forwardJ/ψ−pscattering amplitude fromJ/ψphotoproduction on protons around threshold
2016
We provide an updated analysis of the forward $J/\ensuremath{\psi}$-p scattering amplitude, relating its imaginary part to $\ensuremath{\gamma}p\ensuremath{\rightarrow}J/\ensuremath{\psi}p$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}c\overline{c}X$ cross section data, and calculating its real part through a once-subtracted dispersion relation. From a global fit to both differential and total cross section data, we extract a value for the spin-averaged $J/\ensuremath{\psi}$-p s-wave scattering length ${a}_{\ensuremath{\psi}p}=0.046\ifmmode\pm\else\textpm\fi{}0.005\text{ }\text{ }\mathrm{fm}$, which can be translated into a $J/\ensuremath{\psi}$ binding energy in nuclear matter of ${B}_…
Stochastic Dynamics of Ferroelectric Polarization
2008
This study is addressed to the conceptual and technical problems emerging for ferroelectric systems out of thermodynamic equilibrium. The theoretical setup includes a lattice of interacting cells, each cell obeying regular dynamics determined by Ginzburg-Landau model Hamiltonians whereas relaxation toward minimum energy state is reproduced by thermal environment. Representative examples include polarization response of a single lattice cell, birth of a domain as triggered by the ergodicity breaking, and the effect of nonlocal electroelastic interaction all evidenced combining the Fokker-Planck, imaginary time Schrodinger and symplectic integration techniques.
Theory and modeling of polarization switching in ferroelectrics
2005
Abstract Kinetics of polarization response in ferroelectrics is reproduced within Langevin, Fokker–Planck and imaginary time Schrodinger equation techniques for energy functionals of growing complexity modeling an assembly of coarse grained particles with attractive first neighbor interaction. Symplectic integration based numerical approach captures dynamic hysteresis, polarization switching, and spatially extended stationary polarization. Solution of relevant nonstationary problem is adapted to large scale parallel computing.
Neoliberalism and the moral economy of fraud
2019
In the popular imaginary, corrupt officials and criminal elites have populated the global South – and especially Africa – since the 1980s. In the aftermath of the 2008 financial crisis and with the...
Hypergestures in Complex Time: Creative Performance Between Symbolic and Physical Reality
2015
Musical performance and composition imply hypergestural transformation from symbolic to physical reality and vice versa. But most scores require movements at infinite physical speed that can only be performed approximately by trained musicians. To formally solve this divide between symbolic notation and physical realization, we introduce complex time (\(\mathbb {C}\)-time) in music. In this way, infinite physical speed is “absorbed” by a finite imaginary speed. Gestures thus comprise thought (in imaginary time) and physical realization (in real time) as a world-sheet motion in space-time, corresponding to ideas from physical string theory. Transformation from imaginary to real time gives us…
Splitting Magnitude Response into Real and Imaginary Parts
2017
The determination of real and imaginary parts from magnitude responses is studied for causal linear time-invariant systems having monotonic impulse responses. It is demonstrated that the problem can be interpreted as a special filtering task in the Mellin transform domain having a diffuse magnitude response bounded by the magnitude responses of the filters corresponding to zero and maximum imaginary parts prescribed by the Kronig-Kramers relations. Discrete-time filters processing geometrically sampled magnitude responses are designed for determining the real and imaginary parts. Testing results are presented verifying the performance of the filters.
Pion-induced η production on nuclei
1990
Abstract Low-energy η production on nuclei is investigated in a DWIA framework, using a Green function method. The η potential is constructed by folding medium-modified η N → S 11 → η N scattering amplitudes with nuclear wave functions. A phenomenological spreading potential is introduced for the intermediate S 11 resonance. Calculated ( π + , p ) η cross sections on 12 C and 16 O with the spreading potential having an imaginary part of the order of −50 ∼ −100 MeV compare favorably with recent experimental data. It is also shown that the energy dependence of the ( π + , η ) inclusive spectra is nicely reproduced, though the magnitude is somewhat underestimated.
Kontsevich–Zagier Periods
2017
We compare the set of Kontsevich–Zagier periods defined by integrals over semi-algebraic subsets of \(\mathbb {R}^n\) with cohomological periods.
House Without Rooms
2019
Una riflessione letteraria e architettonica sul progetto House Whitout Rooms di Raimund Abraham, elaborata nell’ambito del Laboratorio Aperto - Omaggio a Dedalo svoltasi al Palazzo Belmonte-Riso durante la Via dei Librai 2018. La Casa senza stanze come interno inospitale, nel quale trovare il disagio necessario per desiderare la fuga.