1,371 research outputs found
FOR WORKSHOP: THE INCOMPUTABLE,
of virtual machinery with “physically indefinable ” functions What’s Meta-Morphogenesis? A partial answer: Evolution, individual development, learning, and cultural change producing new mechanisms of evolution, individual development, learning, and cultural chang
Rare tau Decays in R-parity Violating Supersymmetry
We constrain, from rare tau decays, several combinations of and
type couplings coming from Supersymmetry without R-parity. The
processes that we consider are tau --> l M, tau --> l_i l_j l_k, and tau --> l
gamma, where l stands for either e or mu, and M is the generic symbol for a
meson. We update several existing bounds, and provide a few new ones too.Comment: 12 pages, no figure
One-loop Beta Functions for the Orientable Non-commutative Gross-Neveu Model
We compute at the one-loop order the beta-functions for a renormalisable
non-commutative analog of the Gross Neveu model defined on the Moyal plane. The
calculation is performed within the so called x-space formalism. We find that
this non-commutative field theory exhibits asymptotic freedom for any number of
colors. The beta-function for the non-commutative counterpart of the Thirring
model is found to be non vanishing.Comment: 16 pages, 9 figure
Network synchronization: Optimal and Pessimal Scale-Free Topologies
By employing a recently introduced optimization algorithm we explicitely
design optimally synchronizable (unweighted) networks for any given scale-free
degree distribution. We explore how the optimization process affects
degree-degree correlations and observe a generic tendency towards
disassortativity. Still, we show that there is not a one-to-one correspondence
between synchronizability and disassortativity. On the other hand, we study the
nature of optimally un-synchronizable networks, that is, networks whose
topology minimizes the range of stability of the synchronous state. The
resulting ``pessimal networks'' turn out to have a highly assortative
string-like structure. We also derive a rigorous lower bound for the Laplacian
eigenvalue ratio controlling synchronizability, which helps understanding the
impact of degree correlations on network synchronizability.Comment: 11 pages, 4 figs, submitted to J. Phys. A (proceedings of Complex
Networks 2007
Femtoscopy of the system shape fluctuations in heavy ion collisions
Dipole, triangular, and higher harmonic flow that have an origin in the
initial density fluctuations has gained a lot of attention as they can provide
additional important information about the dynamical properties (e.g.
viscosity) of the system. The fluctuations in the initial geometry should be
also reflected in the detail shape and velocity field of the system at
freeze-out. In this talk I discuss the possibility to measure such fluctuations
by means of identical and non-identical particle interferometry.Comment: 4 pages, Proceedings of Quark Matter 2011 Conference, May 23 - May
28, Annecy, Franc
Cosmology with Hypervelocity Stars
In the standard cosmological model, the merger remnant of the Milky Way and
Andromeda (Milkomeda) will be the only galaxy remaining within our event
horizon once the Universe has aged by another factor of ten, ~10^{11} years
after the Big Bang. After that time, the only extragalactic sources of light in
the observable cosmic volume will be hypervelocity stars being ejected
continuously from Milkomeda. Spectroscopic detection of the velocity-distance
relation or the evolution in the Doppler shifts of these stars will allow a
precise measurement of the vacuum mass density as well as the local matter
distribution. Already in the near future, the next generation of large
telescopes will allow photometric detection of individual stars out to the edge
of the Local Group, and may target the ~10^{5+-1} hypervelocity stars that
originated in it as cosmological tracers.Comment: 4 pages, 2 figures, accepted for publication in the Journal of
Cosmology and Astroparticle Physics (JCAP, 2011
Divergence-free Nonrenormalizable Models
A natural procedure is introduced to replace the traditional, perturbatively
generated counter terms to yield a formulation of covariant, self-interacting,
nonrenormalizable scalar quantum field theories that has the added virtue of
exhibiting a divergence-free perturbation analysis. To achieve this desirable
goal it is necessary to reexamine the meaning of the free theory about which
such a perturbation takes place.Comment: 22 pages. Version accepted for publication; involves modest addition
to the end of Sec.
Instabilities at [110] Surfaces of d_{x^2-y^2} Superconductors
We compare different scenarios for the low temperature splitting of the
zero-energy peak in the local density of states at (110) surfaces of
d_{x^2-y^2}-wave superconductors, observed by Covington et al.
(Phys.Rev.Lett.79 (1997), 277). Using a tight binding model in the
Bogolyubov-de Gennes treatment we find a surface phase transition towards a
time-reversal symmetry breaking surface state carrying spontaneous currents and
an s+id-wave state. Alternatively, we show that electron correlation leads to a
surface phase transition towards a magnetic state corresponding to a local spin
density wave state.Comment: 4 pages, 5 figure
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