Uncertainty and stepwise investment

We analyze the optimal investment strategy of a firm that can complete a project either in one stage at a single freely chosen time point or in incremental steps at distinct time points. The presence of economies of scale gives rise to the following trade-off: lumpy investment has a lower total cost, but stepwise investment gives more flexibility by letting the firm choose the timing individually for each stage. Our main question is how uncertainty in market development affects this trade-off. The answer is unambiguous and in contrast with a conventional real-options intuition: higher uncertainty makes the single-stage investment more attractive relative to the more flexible stepwise investment strategy

Lambda(1520) measurements at the GlueX experiment

This thesis presents the first measurements of the photon beam asymmetry Sigma, spin-density matrix elements and differential cross-sections in Lambda(1520) photoproduction at photon beam energies between 8.2 GeV and 8.8 GeV. These measurements will help to constrain physics models, describing the production process of hadrons at high photon energies, as they are needed in the search for exotic mesons. The data used in this analysis were recorded using the GlueX beamline and detector in Hall D of the Thomas Jefferson National Accelerator Facility (JLab) in Virginia, USA. JLab provides a 12 GeV electron beam which is converted to a linearly polarised photon beam on a thin diamond, via the coherent bremsstrahlung technique. The photon beam is incident on a liquid hydrogen target where it can produce various meson and baryon resonances such as the Lambda(1520). The GlueX detector setup surrounding the target is able to detect both charged and neutral final state particles resulting from the reaction. Careful analysis of their momentum and angular distributions allows the determination of the observables presented in this work. For the extraction of physics observables the sPlot method was used together with unbinned extended maximum likelihood fitting and Markov Chain Monte Carlo methods. The effect of longitudinal phase space analyses was studied and resulted in a publication. So far, previous measurements for this reaction have only been made at much lower or higher energies. This is the first measurement of this reaction in the energy range of GlueX. This work also provides the first measurement of polarised spin-density matrix elements for this reaction channel. These are critical steps towards GlueX’s main goal, which is to establish and map out the spectrum of exotic hybrid mesons, an important milestone in our understanding of quantum chromo dynamics and the strong force

Photoproduction of the Λ\Lambda(1520) hyperon with a 9 GeV photon beam at GlueX

The GlueX experiment is located at the Thomas Jefferson National Accelerator Facility (JLab) in Newport News, VA, USA. It features a hermetic 4$\pi$ detector with excellent tracking and calorimetry capabilities. Its 9 GeV linearly polarized photon beam is produced from the 12 GeV electron beam, delivered by JLab's Continuous Electron Beam Accelerator Facility (CEBAF), via bremsstrahlung on a thin diamond and is incident on a LH2 target. GlueX recently finished its first data taking period and published first results. The main goal of GlueX is to measure gluonic excitations of mesons. These so-called hybrid or exotic mesons are predicted by Quantum Chromodynamics (QCD) but haven't been experimentally confirmed yet. They can have quantum numbers not accessible by ordinary quark-antiquark pairs which helps in identifying them using partial wave analysis techniques. The search for exotic mesons requires a very good understanding of photoproduction processes in a wide range of final states, one of them being $pK^{+}K^{-}$ which contains many meson and baryon reactions. The $\Lambda$(1520) is a prominent hyperon resonance in this final state and is the subject of this presentation. This talk will give an introduction to the GlueX experiment and show preliminary results for the photoproduction of the $\Lambda$(1520) hyperon. The measurement of important observables like the photon beam asymmetry and spin-density matrix elements will be discussed and an outlook to possible measurements of further hyperon states in the $pK^{+}K^{-}$ final state will be given.Comment: 6 pages, 6 figures, proceedings for the International Nuclear Physics Conference 2019 (INPC 2019

The Strangeness Program at GlueX

The GlueX experiment located at Jefferson Lab studies the spectrum of hadrons using photoproduction on a LH2 target in a wide variety of final states. With its detector system capable of measuring neutral and charged final state particles over almost the full solid angle, and very good particle identification capabilities, GlueX can measure many different hadrons containing strangeness. A linearly polarized photon beam allows the measurement of polarization observables, which contain information about the production mechanisms involved in generating strange particles in photoproduction. In addition, GlueX can perform precise cross-section measurements, which help to study the spectrum of strange hadrons. In this presentation, the GlueX experiment is introduced, and recent progress of its strangeness program is discussed. We present recent results on Σ0 beam asymmetries, Λ(1520) spin-density matrix elements and ongoing studies of the Λ(1405) lineshape. We also present our recent progress on measurements of ΛΛ̅ and Ξ(∗) photoproduction. Also, future prospects for strangeness measurements at GlueX are discussed

Photoproduction of the Λ(1520) Hyperon with a 9 GeV Photon Beam at GlueX

The GlueX experiment is located at the Thomas Jefferson National Accelerator Facility (JLab) in Newport News, VA, USA. It features a hermetic 4π detector with excellent tracking and calorimetry capabilities. Its 9 GeV linearly polarized photon beam is produced from the 12 GeV electron beam, delivered by JLab's Continuous Electron Beam Accelerator Facility (CEBAF), via bremsstrahlung on a thin diamond and is incident on a LH2 target. GlueX recently finished its first data taking period and published first results. The main goal of GlueX is to measure gluonic excitations of mesons. These so-called hybrid or exotic mesons are predicted by Quantum Chromodynamics (QCD) but haven't been experimentally confirmed yet. They can have quantum numbers not accessible by ordinary quark-antiquark pairs which helps in identifying them using partial wave analysis techniques. The search for exotic mesons requires a very good understanding of photoproduction processes in a wide range of final states, one of them being pK+K− which contains many meson and baryon reactions. The Λ(1520) is a prominent hyperon resonance in this final state and is the subject of this presentation. This talk will give an introduction to the GlueX experiment and show preliminary results for the photoproduction of the Λ(1520) hyperon. The measurement of important observables like the photon beam asymmetry and spin-density matrix elements will be discussed and an outlook to possible measurements of further hyperon states in the pK+K− final state will be given

Special Libraries, October 1940

Volume 31, Issue 8https://scholarworks.sjsu.edu/sla_sl_1940/1007/thumbnail.jp

Neural computations underlying inverse reinforcement learning in the human brain

In inverse reinforcement learning an observer infers the reward distribution available for actions in the environment solely through observing the actions implemented by another agent. To address whether this computational process is implemented in the human brain, participants underwent fMRI while learning about slot machines yielding hidden preferred and non-preferred food outcomes with varying probabilities, through observing the repeated slot choices of agents with similar and dissimilar food preferences. Using formal model comparison, we found that participants implemented inverse RL as opposed to a simple imitation strategy, in which the actions of the other agent are copied instead of inferring the underlying reward structure of the decision problem. Our computational fMRI analysis revealed that anterior dorsomedial prefrontal cortex encoded inferences about action-values within the value space of the agent as opposed to that of the observer, demonstrating that inverse RL is an abstract cognitive process divorceable from the values and concerns of the observer him/herself

Thermal equilibrium and statistical thermometers in special relativity

There is an intense debate in the recent literature about the correct generalization of Maxwell's velocity distribution in special relativity. The most frequently discussed candidate distributions include the Juettner function as well as modifications thereof. Here, we report results from fully relativistic one-dimensional (1D) molecular dynamics (MD) simulations that resolve the ambiguity. The numerical evidence unequivocally favors the Juettner distribution. Moreover, our simulations illustrate that the concept of 'thermal equilibrium' extends naturally to special relativity only if a many-particle system is spatially confined. They make evident that 'temperature' can be statistically defined and measured in an observer frame independent way.Comment: version accepted for publication (5 pages), part of the introduction modified, new figures, additional reference