1,081 research outputs found
Weak Stability and a Bargaining Set for the Marriage Model
In this note we introduceweak stability, a relaxation of the concept of stability for the marriage model by assuming that the agents are no longer myopic in choosing a blocking pair. The new concept is based on threats within blocking pairs: an individually rational matching is weakly stable if for every blocking pair one of themembers can find a more attractive partner with whom he forms another blocking pair for the original matching. Our main result is that under the assumption of strict preferences, the set of weakly stable and weakly efficient matchings coincides with the bargaining set of Zhou (1994) for this context.matching;(weak) stability;bargaining set
Job creation and job destruction in Estonia: labour reallocation and structural changes
This paper documents and analyses gross job flows and their determinants in Estonia over the years 1995-2001, using a unique database from the Estonian Business Registry. This database contains all (including also micro and small firms) officially registered firms in Estonia, the total number being almost 52,000. There are several important findings in the paper. Our results show that job flows (job creation and job destruction rates) have been extremely high in Estonia and are comparable to the levels documented for the US. These rates have not decreased recently, although worker flows (transitions between labour market states) have dropped. We also found that the firm-specific component in job flows excess of employment change had relatively lower importance than in western studies due to the emergence of small and medium-sized enterprises and labour reallocation between the economic sectors. The high inter-sectoral mobility has helped maintain high levels of job flows, while both are high also due to a favourable institutional environment, especially due to low start-up costs and a large share of micro enterprises
Creative destruction and transition: the effects of firm entry and exit on productivity growth in Estonia
This paper presents one of the first studies of firm demographics in Estonia, particularly, on the processes of firm entry and exit as well as survival analysis of new firms. Also decompositions of productivity change into components consisting of resource reallocation, firm entry and exit, and productivity growth within continuing firms is carried out. Our results, derived from a novel database of the population of Estonian firms, show that firm turnover has been rather high in Estonia during the observed period from 1995 to 2001, resulting from low institutional entry barriers and emergence of the SME sector. The high survival rates for new firms and surviving firms' relatively fast growth could reflect their relatively high productivity compared to incumbent firms and changes in the sectoral structure of the economy. The decomposition of productivity change shows that the high productivity growth has been mostly from within-firm productivity growth (e.g. the adoption of new production technologies and organizational changes), but the reallocation of production factors (especially the exit of low productivity units) has played an important role as well
Renormalization of dimension-six operators relevant for the Higgs decays
The discovery of the Higgs boson has opened a new window to test the SM
through the measurements of its couplings. Of particular interest is the
measured Higgs coupling to photons which arises in the SM at the one-loop
level, and can then be significantly affected by new physics. We calculate the
one-loop renormalization of the dimension-six operators relevant for
, which can be potentially important since
it could, in principle, give log-enhanced contributions from operator mixing.
We find however that there is no mixing from any current-current operator that
could lead to this log-enhanced effect. We show how the right choice of
operator basis can make this calculation simple. We then conclude that
can only be affected by RG mixing from
operators whose Wilson coefficients are expected to be of one-loop size, among
them fermion dipole-moment operators which we have also included.Comment: 21 pages. Improved version with h -> gamma Z results added and
structure of anomalous-dimension matrix determined further. Conclusions
unchange
Numerical evolution of matter in dynamical axisymmetric black hole spacetimes. I. Methods and tests
We have developed a numerical code to study the evolution of self-gravitating
matter in dynamic black hole axisymmetric spacetimes in general relativity. The
matter fields are evolved with a high-resolution shock-capturing scheme that
uses the characteristic information of the general relativistic hydrodynamic
equations to build up a linearized Riemann solver. The spacetime is evolved
with an axisymmetric ADM code designed to evolve a wormhole in full general
relativity. We discuss the numerical and algorithmic issues related to the
effective coupling of the hydrodynamical and spacetime pieces of the code, as
well as the numerical methods and gauge conditions we use to evolve such
spacetimes. The code has been put through a series of tests that verify that it
functions correctly. Particularly, we develop and describe a new set of testbed
calculations and techniques designed to handle dynamically sliced,
self-gravitating matter flows on black holes, and subject the code to these
tests. We make some studies of the spherical and axisymmetric accretion onto a
dynamic black hole, the fully dynamical evolution of imploding shells of dust
with a black hole, the evolution of matter in rotating spacetimes, the
gravitational radiation induced by the presence of the matter fields and the
behavior of apparent horizons through the evolution.Comment: 42 pages, 20 figures, submitted to Phys Rev
Axions and their Relatives
A review of the status of axions and axion-like particles is given. Special
attention is devoted to the recent results of the PVLAS collaboration, which
are in conflict with the CAST data and with the astrophysical constraints.
Solutions to the puzzle and the implications for new physics are discussed. The
question of axion-like particles being dark matter is also addressed.Comment: Updated version of an invited talk at the Axion Training (CERN,
December 2005). To appear as a Lecture Notes in Physics (Springer-Verlag),
edited by B. Beltran, M. Kuster and G. Raffel
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