Creative Careers: The Life Cycles of Nobel Laureates in Economics

This paper studies life cycle creativity among Nobel laureate economists. We identify two distinct life cycles of scholarly creativity. Experimental innovators work inductively, accumulating knowledge from experience. Conceptual innovators work deductively, applying abstract principles. We find that conceptual innovators do their most important work earlier in their careers than experimental laureates. For instance, our estimates imply that the probability that the most conceptual laureate publishes his single best work peaks at age 25 compared to the mid-50s for the most experimental laureate. Thus while experience benefits experimental innovators, newness to a field benefits conceptual innovators.

Cosmological Density Perturbations with a Scale-Dependent Newton's G

We explore possible cosmological consequences of a running Newton's constant $G ( \Box )$, as suggested by the non-trivial ultraviolet fixed point scenario in the quantum field-theoretic treatment of Einstein gravity with a cosmological constant term. In particular we focus here on what possible effects the scale-dependent coupling might have on large scale cosmological density perturbations. Starting from a set of manifestly covariant effective field equations derived earlier, we systematically develop the linear theory of density perturbations for a non-relativistic, pressure-less fluid. The result is a modified equation for the matter density contrast, which can be solved and thus provides an estimate for the growth index parameter $\gamma$ in the presence of a running $G$. We complete our analysis by comparing the fully relativistic treatment with the corresponding results for the non-relativistic (Newtonian) case, the latter also with a weakly scale dependent $G$.Comment: 54 pages, 4 figure

Production of Milky Way structure by the Magellanic Clouds

Previous attempts at disturbing the galactic disk by the Magellanic Clouds relied on direct tidal forcing. However, by allowing the halo to actively respond rather than remain a rigid contributor to the rotation curve, the Clouds may produce a wake in the halo which then distorts the disk. Recent work reported here suggests that the Magellanic Clouds use this mechanism to produce disk distortions sufficient to account for both the radial location, position angle and sign of the HI warp and observed anomalies in stellar kinematics towards the galactic anticenter and LSR motion.Comment: 8 pages, uuencoded compressed PostScript, no figures, html version with figures and mpeg simulations available at http://www-astro.phast.umass.edu/Preprints/martin/martin1/lmc_online.htm

Catalytic reaction between adsorbed oxygen and hydrogen on Rh(111)

Abstract unavailable

The resultant parameters of effective theory

This is the 4-th paper in the series devoted to a systematic study of the problem of mathematically correct formulation of the rules needed to manage an effective field theory. Here we consider the problem of constructing the full set of essential parameters in the case of the most general effective scattering theory containing no massless particles with spin J > 1/2. We perform the detailed classification of combinations of the Hamiltonian coupling constants and select those which appear in the expressions for renormalized S-matrix elements at a given loop order.Comment: 21 pages, 4 LaTeX figures, submitted to Phys. Rev.

Implementing PCAC in Nonperturbative Models of Pion Production

Traditional few-body descriptions of pion production use integral equations to sum the strong interactions nonperturbatively. Although much physics is thereby included, there has not been a practical way of incorporating the constraints of chiral symmetry into such approaches. Thus the traditional few-body descriptions fail to reflect the underlying theory of strong interactions, QCD, which is largely chirally symmetric. In addition, the lack of chiral symmetry in the few-body approaches means that their predictions of pion production are in principle not consistent with the partial conservation of axial current (PCAC), a fact that has especially large consequences at low energies. We discuss how the recent introduction of the ``gauging of equations method'' can be used to include PCAC into traditional few-body descriptions and thereby solve this long standing problemComment: Contribution to Proceedings, 1st Asia-Pacific Conference on Few-Body Problems in Physics, Noda/Kashiwa, Japan, 23-28 August 1999, to be published by Springer-Verlag as "Few-Body Systems Supplement". 7 pages, revtex, epsf, 3 Postscript figure

Comments on the tethered galaxy problem

In a recent paper Davis et al. make the counter intuitive assertion that a galaxy held `tethered' at a fixed distance from our own could emit blueshifted light. Moreover, this effect may be derived from the simplest Friedmann-Robertson-Walker spacetimes and the (0.3,0.7) case which is believed to be a good late time model of our own universe. In this paper we recover the previous authors' results in a more transparent form. We show how their results rely on a choice of cosmological distance scale and revise the calculations in terms of observable quantities which are coordinate independent. By this method we see that, although such a tethering would reduce the redshift of a receding object, it would not do so sufficiently to cause the proposed blueshift. The effect is also demonstrated to be much smaller than conjectured below the largest intergalactic scales. We also discuss some important issues, raised by this scenario, relating to the interpretation of redshift and distance in relativistic cosmology.Comment: 6 pages, 3 figures, submitted to Am.J.Phy

Oxidation of carbon monoxide over Ag (111) by preadsorbed active oxygen studied by XPS and UPS

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Higgs Inflation, Quantum Smearing and the Tensor to Scalar Ratio

In cosmic inflation driven by a scalar gauge singlet field with a tree level Higgs potential, the scalar to tensor ratio r is estimated to be larger than 0.036, provided the scalar spectral index n_s >= 0.96. We discuss quantum smearing of these predictions arising from the inflaton couplings to other particles such as GUT scalars, and show that these corrections can significantly decrease r. However, for n_s >= 0.96, we obtain r >= 0.02 which can be tested by the Planck satellite.Comment: 10 pages, 3 figures and 3 table

Periodic Gravitational Waves From Small Cosmic String Loops

We consider a population of small, high-velocity cosmic string loops. We assume the typical length of these loops is determined by the gravitational radiation scale and use the results of \cite{Polchinski:2007rg} which pointed out their highly relativistic nature. A study of the gravitational wave emission from such a population is carried out. The large Lorentz boost involved causes the lowest harmonics of the loops to fall within the frequency band of the LIGO detector. Due to this feature the gravitational waves emitted by such loops can be detected in a periodic search rather than in burst or stochastic analysis. It is shown that, for interesting values of the string tension (10^{-10}\lsim G\mu\lsim 10^{-8}) the detector can observe loops at reasonably high redshifts and that detection is, in principle, possible. We compute the number of expected observations produced by such a process. For a 10 hour search we find that this number is of order $O(10^{-4})$. This is a consequence of the low effective number density of the loops traveling along the line of sight. However, small probabilities of reconnection and longer observation times can improve the result.Comment: 1+15 pages, 7 figure