15,148 research outputs found
Variational Principle in the Algebra of Asymptotic Fields
This paper proposes a variational principle for the solutions of quantum
field theories in which the ``trial functions'' are chosen from the algebra of
asymptotic fields, and illustrates this variational principle in simple cases.Comment: 15 pages, Latex, no figure
Virtual Transfer Price Negotiations:Unintended Interactions with Incentive Systems
Despite decades of research concerning the impact of computer-mediated communication (CMC) on decision-making, the potential interaction with the organization\u27s management control system has just recently received attention. Media naturalness theory is used to develop hypotheses concerning the interactions of communication medium with the incentive pay scheme, a ubiquitous aspect of management control systems. A laboratory experiment was used to examine the interactions between two treatments: face-to-face negotiations versus virtual (computer-mediated) negotiations and cooperative versus competitive incentive pay schemes. Buyer-seller dyads negotiated the price and quantity of the transferred goods. Results indicate that while virtual negotiations are more efficient in terms of time than face-to-face negotiations, there is not a significant interaction with the incentive pay scheme for efficiency. However. results also indicate that virtual negotiations are less effective in terms of optimal quantity (organizational profit) than face-to-face, and that there is a significant interaction with the incentive pay scheme. Virtual negotiations have the unintended consequence of reducing the effectiveness (organizational profitability) of the negotiations
The chameleon groups of Richard J. Thompson: automorphisms and dynamics
The automorphism groups of several of Thompson's countable groups of
piecewise linear homeomorphisms of the line and circle are computed and it is
shown that the outer automorphism groups of these groups are relatively small.
These results can be interpreted as stability results for certain structures of
PL functions on the circle. Machinery is developed to relate the structures on
the circle to corresponding structures on the line
Non-Pauli Effects from Noncommutative Spacetimes
Noncommutative spacetimes lead to nonlocal quantum field theories (qft's)
where spin-statistics theorems cannot be proved. For this reason, and also
backed by detailed arguments, it has been suggested that they get corrected on
such spacetimes leading to small violations of the Pauli principle. In a recent
paper \cite{Pauli}, Pauli-forbidden transitions from spacetime noncommutativity
were calculated and confronted with experiments. Here we give details of the
computation missing from this paper. The latter was based on a spacetime
different from the Moyal plane. We argue that it
quantizes time in units of . Energy is then conserved only mod
. Issues related to superselection rules raised by non-Pauli
effects are also discussed in a preliminary manner.Comment: 15 Pages, 1 Table, Full details and further developments of
arXiv:1003.2250. This version is close to the one accepted by JHE
Canonical Partition Functions for Parastatistical Systems of any order
A general formula for the canonical partition function for a system obeying
any statistics based on the permutation group is derived. The formula expresses
the canonical partition function in terms of sums of Schur functions. The only
hitherto known result due to Suranyi [ Phys. Rev. Lett. {\bf 65}, 2329 (1990)]
for parasystems of order two is shown to arise as a special case of our general
formula. Our results also yield all the relevant information about the
structure of the Fock spaces for parasystems.Comment: 9 pages, No figures, Revte
Tidal Evolution of Close-in Extra-Solar Planets
The distribution of eccentricities e of extra-solar planets with semi-major
axes a > 0.2 AU is very uniform, and values for e are relatively large,
averaging 0.3 and broadly distributed up to near 1. For a < 0.2 AU,
eccentricities are much smaller (most e < 0.2), a characteristic widely
attributed to damping by tides after the planets formed and the protoplanetary
gas disk dissipated. Most previous estimates of the tidal damping considered
the tides raised on the planets, but ignored the tides raised on the stars.
Most also assumed specific values for the planets' poorly constrained tidal
dissipation parameter Qp. Perhaps most important, in many studies, the strongly
coupled evolution between e and a was ignored. We have now integrated the
coupled tidal evolution equations for e and a over the estimated age of each
planet, and confirmed that the distribution of initial e values of close-in
planets matches that of the general population for reasonable Q values, with
the best fits for stellar and planetary Q being ~10^5.5 and ~10^6.5,
respectively. The accompanying evolution of a values shows most close-in
planets had significantly larger a at the start of tidal migration. The earlier
gas disk migration did not bring all planets to their current orbits. The
current small values of a were only reached gradually due to tides over the
lifetimes of the planets. These results may have important implications for
planet formation models, atmospheric models of "hot Jupiters", and the success
of transit surveys.Comment: accepted to Ap
A model of ballistic aggregation and fragmentation
A simple model of ballistic aggregation and fragmentation is proposed. The
model is characterized by two energy thresholds, Eagg and Efrag, which
demarcate different types of impacts: If the kinetic energy of the relative
motion of a colliding pair is smaller than Eagg or larger than Efrag, particles
respectively merge or break; otherwise they rebound. We assume that particles
are formed from monomers which cannot split any further and that in a
collision-induced fragmentation the larger particle splits into two fragments.
We start from the Boltzmann equation for the mass-velocity distribution
function and derive Smoluchowski-like equations for concentrations of particles
of different mass. We analyze these equations analytically, solve them
numerically and perform Monte Carlo simulations. When aggregation and
fragmentation energy thresholds do not depend on the masses of the colliding
particles, the model becomes analytically tractable. In this case we show the
emergence of the two types of behavior: the regime of unlimited cluster growth
arises when fragmentation is (relatively) weak and the relaxation towards a
steady state occurs when fragmentation prevails. In a model with mass-dependent
Eagg and Efrag the evolution with a cross-over from one of the regimes to
another has been detected
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