31,725 research outputs found
Perturbation of Initial Stability of an FSAPDS Projectile
For a spinning projectile, the initial stability condition is 2 = 1+ (4 K3 / K22) > 0. In the presentstudy, this condition has been modified for the malalignments arising due to pressure gradientand damping moment for an FSAPDS projectile. The equations of motion are established for thefirst phase of motion. A mathematical model for the first phase of motion has been developed.The effect of perturbation on the trajectory and stability of motion are discussed. It is provedthat if 3 K(a parameter appearing due to perturbation)(-K22 2 /4 ), the initial stability ofmotion will breakdown
Pretransitional behavior of viscoelastic parameters at the nematic to twist-bend nematic phase transition in flexible: N -mers
© 2019 the Owner Societies. We report dynamic light scattering measurements of the orientational (Frank) elastic constants and associated viscosities among a homologous series of a liquid crystalline dimer, trimer, and tetramer exhibiting a uniaxial nematic (N) to twist-bend nematic (NTB) phase transition. The elastic constants for director splay (K11), twist (K22) and bend (K33) exhibit the relations K11 > K22 > K33 and K11/K22 > 2 over the bulk of the N phase. Their behavior near the N-NTB transition shows dependency on the parity of the number (n) of the rigid mesomorphic units in the flexible n-mers. Namely, the bend constant K33 in the dimer and tetramer turns upward and starts increasing close to the transition, following a monotonic decrease through most of the N phases. In contrast, K33 for the trimer flattens off just above the transition and shows no pretransitional enhancement. The twist constant K22 increases pretransitionally in both even and odd n-mers, but more weakly so in the trimer, while K11 increases steadily on cooling without evidence of pretransitional behavior in any n-mer. The viscosities associated with pure splay, twist-dominated twist-bend, and pure bend fluctuations in the N phase are comparable in magnitude to those of rod-like monomers. All three viscosities increase with decreasing temperature, but the bend viscosity in particular grows sharply near the N-NTB transition. The N-NTB pretransitional behavior is shown to be in qualitative agreement with the predictions of a coarse-grained theory, which models the NTB phase as a "pseudo-layered" structure with the symmetry (but not the mass density wave) of a smectic-A∗ phase
Heavy Quark Impact Factor at Next-to-leading Level
We further analyze the definition and the calculation of the heavy quark
impact factor at next-to-leading (NL) log(s) level, and we provide its
analytical expression in a previously proposed k-factorization scheme. Our
results indicate that k-factorization holds at NL level with a properly chosen
energy scale, and with the same gluonic Green's function previously found in
the massless probe case.Comment: LaTeX2e, 17pp, 2 figures, uses JHEP.cls. The complete paper,
including figures, is also available via anonymous ftp at
ftp://ttpux2.physik.uni-karlsruhe.de/ttp00/ttp00-06, or via www at
http://www-ttp.physik.uni-karlsruhe.de/Preprints
Quark-Antiquark-Gluon Jets in DIS Diffractive Dissociation
We study the diffractive production of jets with large transverse
momenta in the region of large diffractive masses (small ). Cross
sections for transverse and longitudinal photons are obtained in the leading
log 1/x_{\fP} and log approximation, keeping all powers in log
. We perform a numerical study and illustrate the angular
distribution of the three jets. We also estimate the integrated diffractive
three jet cross section and compare with the dijet cross section obtained
before.Comment: 28 pages (Latex), 20 figures (Postscript
The Electroweak Standard Model in the Axial Gauge
We derive the Feynman rules of the standard model in the axial gauge. After
this we prove that the fields and do not correspond to
physical particles. As a consequence, these fields cannot appear as incoming or
outgoing lines in Feynman graphs. We then calculate the contribution of these
fields in the case of a particular decay mode of the top quark.Comment: 16 pages, no figures. Added derivation of polarization su
On a generalization of Jacobi's elliptic functions and the Double Sine-Gordon kink chain
A generalization of Jacobi's elliptic functions is introduced as inversions
of hyperelliptic integrals. We discuss the special properties of these
functions, present addition theorems and give a list of indefinite integrals.
As a physical application we show that periodic kink solutions (kink chains) of
the double sine-Gordon model can be described in a canonical form in terms of
generalized Jacobi functions.Comment: 18 pages, 9 figures, 3 table
Quasi-doubly periodic solutions to a generalized Lame equation
We consider the algebraic form of a generalized Lame equation with five free
parameters. By introducing a generalization of Jacobi's elliptic functions we
transform this equation to a 1-dim time-independent Schroedinger equation with
(quasi-doubly) periodic potential. We show that only for a finite set of
integral values for the five parameters quasi-doubly periodic eigenfunctions
expressible in terms of generalized Jacobi functions exist. For this purpose we
also establish a relation to the generalized Ince equation.Comment: 15 pages,1 table, accepted for publication in Journal of Physics
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