Direct search limits on the Littlest Higgs model

Recent direct searches for new massive particles place constraints on the free parameters of the Littlest Higgs model. Depending on the choice of model free parameters, the direct search limit on the global symmetry breaking scale f can range from as low as a few hundred GeV to in excess of 4.5 TeV. The most stringent constraints are from exclusion of the A_H using high-mass dilepton resonance searches. The Z_H provides the best constraint in parameter regions where the A_H decouples from leptons. Current top pair resonance data approach but do not yet reach a useful limit in the anomaly-cancelling case, but do provide a constraint for a limited range of parameters in other cases. A neutral gauge boson is shown to be undetectable in dilepton resonances for a significant range of parameter space due to decoupling from Standard Model leptons, providing a counterexample to broad claims that a new neutral gauge boson (sometimes generically referred to as a Z') is ruled out to a high mass scale.Comment: Conforms to published version. Minor clarifications and corrections, and additions to acknowledgment

The evolution of auditory contrast

This paper reconciles the standpoint that language users do not aim at improving their sound systems with the observation that languages seem to improve their sound systems. Computer simulations of inventories of sibilants show that Optimality-Theoretic learners who optimize their perception grammars automatically introduce a so-called prototype effect, i.e. the phenomenon that the learner’s preferred auditory realization of a certain phonological category is more peripheral than the average auditory realization of this category in her language environment. In production, however, this prototype effect is counteracted by an articulatory effect that limits the auditory form to something that is not too difficult to pronounce. If the prototype effect and the articulatory effect are of a different size, the learner must end up with an auditorily different sound system from that of her language environment. The computer simulations show that, independently of the initial auditory sound system, a stable equilibrium is reached within a small number of generations. In this stable state, the dispersion of the sibilants of the language strikes an optimal balance between articulatory ease and auditory contrast. The important point is that this is derived within a model without any goal-oriented elements such as dispersion constraints

An engineering approach to business model experimentation – an online investment research startup case study

Every organization needs a viable business model. Strikingly, most of current literature is focused on business model design, whereas there is almost no attention for business model validation and implementation and related business model experimentation. The goal of the research as described in this paper is to develop a business model engineering tool for supporting business model management as a continuous design, validation and implementation cycle. The tool is applied to an online investment research startup in roll out and market phase. This paper describes the research as performed in a case study setting by focusing on the design, implementation and evaluation of the business model engineering tool. We also analyze the actual implementation and usage of the business model tool by the online investment research startup by focusing on the most critical actions related to actual business model implementation – i.e. actions with so-called ‘Lollapalooza tendencies’

The violability of backness in retroflex consonants

This paper addresses remarks made by Flemming (2003) to the effect that his analysis of the interaction between retroflexion and vowel backness is superior to that of Hamann (2003b). While Hamann maintained that retroflex articulations are always back, Flemming adduces phonological as well as phonetic evidence to prove that retroflex consonants can be non-back and even front (i.e. palatalised). The present paper, however, shows that the phonetic evidence fails under closer scrutiny. A closer consideration of the phonological evidence shows, by making a principled distinction between articulatory and perceptual drives, that a reanalysis of Flemming’s data in terms of unviolated retroflex backness is not only possible but also simpler with respect to the number of language-specific stipulations

Asymptotic expansions for a remarkable class of random walks

This paper extends the research of Wiegel (J. Math. Phys. 21 (1980) 2111) on random walks which differ from free random walks through the occurrence of an extra weightfactor (−1) at every crossing of a half-line. Starting from a new closed-form expression for the weight distribution of these walks, we derive various integral representations and asymptotic expansions for the total weight of all walks

Decays of the Littlest Higgs Z_H and the Onset of Strong Dynamics

The Little Higgs mechanism, as realized in various models, requires a set of new massive gauge bosons, some of which mix with gauge bosons of the Standard Model. For a range of mixing angles the coupling of gauge bosons to scalars can become strong, ultimately resulting in a breakdown of perturbative calculation. This phenomenon is studied in the Littlest Higgs model, where the approach to strong dynamics is characterized by increasing tree-level decay widths of the neutral Z_H boson to lighter gauge bosons plus multiple scalars. These increasing widths suggest a distinctive qualitative collider signature for the approach to the strong coupling regime of large Higgs and other scalar multiplicities. In this work we catalog the kinematically allowed three-body decays of the Z_H, and calculate the partial width of the process Z_H to Z_L H H. This partial width is found to be larger than the comparable two-body decay Z_H to Z_L H for values of the SU(2) mixing angle cosine(theta) less than 0.13, indicating divergence of the littlest Higgs sigma field expansion at values of cosine(theta) larger than a simple parametric calculation would suggest. Additionally, we present analytical expressions for all two-body decays of the Littlest Higgs Z_H gauge boson, including the effects of all final-state masses

Loanword adaptation as first-language phonological perception

We show that loanword adaptation can be understood entirely in terms of phonological and phonetic comprehension and production mechanisms in the first language. We provide explicit accounts of several loanword adaptation phenomena (in Korean) in terms of an Optimality-Theoretic grammar model with the same three levels of representation that are needed to describe L1 phonology: the underlying form, the phonological surface form, and the auditory-phonetic form. The model is bidirectional, i.e., the same constraints and rankings are used by the listener and by the speaker. These constraints and rankings are the same for L1 processing and loanword adaptation