Why does the clustering of haloes depend on their formation history

We discuss in the framework of the excursion set formalism a recent discovery from N-body simulations that the clustering of haloes of given mass depends on their formation history. We review why the standard implementation of this formalism is unable to explain such dependencies, and we show that this can, in principle, be rectified by implementing in full an ellipsoidal collapse model where collapse depends not only on the overdensity but also on the shape of the initial density field. We also present an alternative remedy for this deficiency, namely the inclusion of collapse barriers for pancakes and filaments, together with the assumption that formation history depends on when these barriers are crossed. We implement both these extensions in a generalised excursion set method, and run large Monte Carlo realisations to quantify the effects. Our results suggest that effects as large as those found in simulations can only arise in the excursion set formalism if the formation history of a halo does indeed depend on the size of its progenitor filaments and pancakes. We also present conditional distributions of progenitor pancakes and filaments for low-mass haloes identified at present epoch, and discuss a recent claim by Mo et.al. that most low-mass haloes were embedded in massive pancakes at $z\sim 2$.Comment: 11 pages, 8 figures, submitted to MNRA

The Schrodinger Wave Functional and Closed String Rolling Tachyon

In this short note we apply Schrodinger picture description of the minisuperspace approach to the closed string tachyon condensation. We will calculate the rate of produced closed string and we will show that the density of high massive closed string modes reaches the string density in time of order one in string units.Comment: 12 page

Nonlocal Dynamics of p-Adic Strings

We consider the construction of Lagrangians that might be suitable for describing the entire $p$-adic sector of an adelic open scalar string. These Lagrangians are constructed using the Lagrangian for $p$-adic strings with an arbitrary prime number $p$. They contain space-time nonlocality because of the d'Alembertian in argument of the Riemann zeta function. We present a brief review and some new results.Comment: 8 page

In search of the elusive long-wave fundamental

Action spectra for threshold detection of flicker (30 Hz) were obtained on 11 deuteranopes under carefully controlled adaptation conditions. Individual differences were large, so that each one of the long-wave fundamentals proposed by different theorists finds reasonable justification in the spectrum measured on at least one deuteranope. Some deuteranopes' spectra are not described by any one of these "fundamentals". To a first approximation at least, trichromats' spectra show the property of linear additivity. One such trichromat's spectrum agreed well with that of a deuteranope with whom he shares a common erythrolabe, and appears to be uninfluenced by his chlorolabe-filled cones.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24130/1/0000387.pd

Zeta Nonlocal Scalar Fields

We consider some nonlocal and nonpolynomial scalar field models originated from p-adic string theory. Infinite number of spacetime derivatives is determined by the operator valued Riemann zeta function through d'Alembertian $\Box$ in its argument. Construction of the corresponding Lagrangians L starts with the exact Lagrangian $\mathcal{L}_p$ for effective field of p-adic tachyon string, which is generalized replacing p by arbitrary natural number n and then taken a sum of $\mathcal{L}_n$ over all n. The corresponding new objects we call zeta scalar strings. Some basic classical field properties of these fields are obtained and presented in this paper. In particular, some solutions of the equations of motion and their tachyon spectra are studied. Field theory with Riemann zeta function dynamics is interesting in its own right as well.Comment: 13 pages, submitted to Theoretical and Mathematical Physic

Tachyons on Dp-branes from Abelian Higgs sphalerons

We consider the Abelian Higgs model in a (p+2)-dimensional space time with topology M^{p+1} x S^1 as a field theoretical toy model for tachyon condensation on Dp-branes. The theory has periodic sphaleron solutions with the normal mode equations resembling Lame-type equations. These equations are quasi-exactly solvable (QES) for specific choices of the Higgs- to gauge boson mass ratio and hence a finite number of algebraic normal modes can be computed explicitely. We calculate the tachyon potential for two different values of the Higgs- to gauge boson mass ratio and show that in comparison to previously studied pure scalar field models an exact cancellation between the negative energy contribution at the minimum of the tachyon potential and the brane tension is possible for the simplest truncation in the expansion about the field around the sphaleron. This gives further evidence for the correctness of Sen's conjecture.Comment: 14 Latex pages including 3 eps-figure

Fire and plant evolution

3 páginas, 1 figura.Peer reviewe

Dual equivalence in models with higher-order derivatives

We introduce a class of higher-order derivative models in (2,1) space-time dimensions. The models are described by a vector field, and contain a Proca-like mass term which prevents gauge invariance. We use the gauge embedding procedure to generate another class of higher-order derivative models, gauge-invariant and dual to the former class. We show that the results are valid in arbitrary (d,1) space-time dimensions when one discards the Chern-Simons and Chern-Simons-like terms. We also investigate duality at the quantum level, and we show that it is preserved in the quantum scenario. Other results include investigations concerning the gauge embedding approach when the vector field couples with fermionic matter, and when one adds nonlinearity.Comment: RevTex4, 14 pages; new version includes duality at the quantum level, and new references. To be published in J. Phys.