1,789,632 research outputs found
Calculation of the persistence length of a flexible polymer chain with short range self-repulsion
For a self-repelling polymer chain consisting of n segments we calculate the
persistence length L(j,n), defined as the projection of the end-to-end vector
on the direction of the j`th segment. This quantity shows some pronounced
variation along the chain. Using the renormalization group and
epsilon-expansion we establish the scaling form and calculate the scaling
function to order epsilon^2. Asymptotically the simple result L(j,n) ~
const(j(n-j)/n)^(2nu-1) emerges for dimension d=3. Also outside the excluded
volume limit L(j,n) is found to behave very similar to the swelling factor of a
chain of length j(n-j)/n. We carry through simulations which are found to be in
good accord with our analytical results. For d=2 both our and previous
simulations as well as theoretical arguments suggest the existence of
logarithmic anomalies.Comment: 28 pages, 8 figures, changed conten
Probing lepton flavor violation signal via e+ e- (gamma gamma) ---> l(i) anti-l(j) in the littlest Higgs model with T-parity at the ILC
In the littlest Higgs model with T-parity, the new interactions between the
mirror leptons and the Standard Model leptons can induce some lepton flavor
violation (LFV) processes at loop level. We study the possibility of the ILC to
probe the LFV production processes . Our results show that the rates of can reach 1 fb in optimal cases after reasonable kinematical
cuts, which implies that these processes may be observed at the ILC
Dirac oscillator with nonzero minimal uncertainty in position
In the context of some deformed canonical commutation relations leading to
isotropic nonzero minimal uncertainties in the position coordinates, a Dirac
equation is exactly solved for the first time, namely that corresponding to the
Dirac oscillator. Supersymmetric quantum mechanical and shape-invariance
methods are used to derive both the energy spectrum and wavefunctions in the
momentum representation. As for the conventional Dirac oscillator, there are
neither negative-energy states for , nor symmetry between the and cases, both features being connected with
supersymmetry or, equivalently, the transformation. In
contrast with the conventional case, however, the energy spectrum does not
present any degeneracy pattern apart from that associated with the rotational
symmetry. More unexpectedly, deformation leads to a difference in behaviour
between the states corresponding to small, intermediate and
very large values in the sense that only for the first ones supersymmetry
remains unbroken, while for the second ones no bound state does exist.Comment: 28 pages, no figure, submitted to JP
On the theory of energy distributions of products of molecular beam reactions involving transient complexes
Theoretical energy distributions of reaction products in molecular beam systems are described for reactions proceeding via transient complexes. Loose and tight transition states are considered for the exit channel. For a loose transition state and the case of l ≫ j, the result is the same as of Safron et al. For the case of a tight transition state exit channel effects are included analogous to steric effects for the reverse reaction. It is shown how, via one mechanism, bending vibrational energy of that transition state can contribute to the translational energy of the reaction products. Expressions are derived for the energy distributions of the products when l ≫ j and j ≫ l
Parity doubling of highly excited mesons
Glozman has proposed that highly excited mesons and baryons fall into parity
doublets, and that the f4(2050) on the leading Regge trajectory should have a
nearly degenerate J^{PC} = 4^{-+} partner. A re-analysis of Crystal Barrel data
does not support this idea. A likely explanation is that centrifugal barriers
on the leading trajectory allow formation of the L=J-1 states, but are too
strong to allow L=J states. Two new polarisation experiments have the potential
for major progress in meson spectroscopy.Comment: 7 pages, 2 figures, 1 table. Further experimental detail added and
additional algebra. Conclusions unchanged. To be published in Physics Letters
Is there a third order phase transition for supercritical fluids?
We prove that according to Molecular Dynamics (MD) simulations of liquid
mixtures of Lennard-Jones (L-J) particles, there is no third order phase
transition in the supercritical regime beyond Andrew's critical point. This
result is in open contrast with recent theoretical studies and experiments
which instead suggest not only its existence but also its universality
regarding the chemical nature of the fluid. We argue that our results are solid
enough to go beyond the limitations of MD and the generic character of L-J
models, thus suggesting a rather smooth liquid-vapor thermodynamic behavior of
fluids in supercritical regime.Comment: 13 pages, 6 figure
Distance-two labelings of digraphs
For positive integers , an -labeling of a digraph is a
function from into the set of nonnegative integers such that
if is adjacent to in and if
is of distant two to in . Elements of the image of are called
labels. The -labeling problem is to determine the
-number of a digraph , which
is the minimum of the maximum label used in an -labeling of . This
paper studies - numbers of digraphs. In particular, we
determine - numbers of digraphs whose longest dipath is of
length at most 2, and -numbers of ditrees having dipaths
of length 4. We also give bounds for -numbers of bipartite
digraphs whose longest dipath is of length 3. Finally, we present a linear-time
algorithm for determining -numbers of ditrees whose
longest dipath is of length 3.Comment: 12 pages; presented in SIAM Coference on Discrete Mathematics, June
13-16, 2004, Loews Vanderbilt Plaza Hotel, Nashville, TN, US
Linear Collisionless Landau Damping in Hilbert Space
The equivalence between the Laplace transform [Landau L., J. Phys. USSR, 10
(1946), 25] and Hermite transform [Zocco and Schekochihin, Phys. Plasmas, 18,
102309 (2011)] solutions of the linear collisionless Landau damping problem is
proven
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