Three- and Four-point correlators of excited bosonic twist fields

We compute three- and four-point correlation functions containing excited bosonic twist fields. Our results can be used to determine properties, such as lifetimes and production rates, of massive string excitations localised at D-brane intersections, which could be signatures of a low string scale even if the usual string resonances are inaccessible to the LHC.Comment: 42 pages, no figure

Discrete symmetries from hidden sectors

We study the presence of abelian discrete symmetries in globally consistent orientifold compactifications based on rational conformal field theory. We extend previous work [1] by allowing the discrete symmetries to be a linear combination of U(1) gauge factors of the visible as well as the hidden sector. This more general ansatz significantly increases the probability of finding a discrete symmetry in the low energy effective action. Applied to globally consistent MSSM-like Gepner constructions we find multiple models that allow for matter parity or Baryon triality.Comment: 20 page

Search for a meteoritic component at the Beaverhead impact structure, Montana

The Beaverhead impact structure, in southwestern Montana, was identified recently by the presence of shatter cones and impactites in outcrops of Proterozoic sandstones of the Belt Supergroup. The cones occur over an area greater than 100 sq km. Because the geologic and tectonic history of this region is long and complex, the outline of the original impact crater is no longer identifiable. The extent of the area over which shatter cones occur suggests, however, that the feature may have been at least 60 km in diameter. The absence of shatter cones in younger sedimentary units suggests that the impact event occurred in late Precambrian or early Paleozoic time. We have collected samples of shocked sandstone from the so-called 'Main Site' of dark-matrix breccias, and of impact breccias and melts from the south end of Island Butte. The melts, occurring often as veins through brecciated sandstone, exhibit a distinctive fluidal texture, a greenish color, and a cryptocrystalline matrix, with small inclusions of deformed sandstone. Samples of the same type, along with country rock, were analyzed previously for major- and trace-element abundances. It was found that, although the major-element composition as relatively uniform, trace-element composition showed variations between the melt material and the adjacent sandstone. These variations were attributed to extensive weathering and hydrothermal alteration. In a more specific search for a possible meteoritic signature in the breccia and the melt material we have conducted a new series of trace-element analyses on powders of our own samples by thermal neutron activation analysis. Our results indicate that Ir abundances in the breccia, the melts, and the adjacent sandstone clasts are no greater than about 0.1 ppb, suggesting no Ir enrichment of the breccia or the melts relative to the country rock. However, both the breccia and the melt material exhibit notable enrichments in Cr (8- and 10-fold), in U (9- and 5-fold), and in the heavy REE's (1.5- and 3-fold), respectively

Optical Design of the SuMIRe PFS Spectrograph

The SuMIRe Prime Focus Spectrograph (PFS), developed for the 8-m class SUBARU telescope, will consist of four identical spectrographs, each receiving 600 fibers from a 2394 fiber robotic positioner at the telescope prime focus. Each spectrograph includes three spectral channels to cover the wavelength range 0.38-1.26 um with a resolving power ranging between 2000 and 4000. A medium resolution mode is also implemented to reach a resolving power of 5000 at 0.8 um. Each spectrograph is made of 4 optical units: the entrance unit which produces three corrected collimated beams and three camera units (one per spectral channel). The beam is split by using two large dichroics; and in each arm, the light is dispersed by large VPH gratings. The proposed optical design was optimized to achieve the requested image quality while simplifying the manufacturing of the whole optical system. The camera design consists in an innovative Schmidt camera observing a large field-of-view (10 degrees) with a very fast beam. To achieve such a performance, the classical spherical mirror is replaced by a catadioptric mirror (i.e meniscus lens with a reflective surface on the rear side of the glass, like a Mangin mirror). This article focuses on the optical architecture of the PFS spectrograph and the perfornance achieved. We will first described the global optical design of the spectrograph. Then, we will focus on the Mangin-Schmidt camera design. The analysis of the optical performance and the results obtained are presented in the last section.Comment: 8 pages - submitted at SPIE Astronomical Telescopes - Instrumentation 2014 - Montrea

Attitude toward information and learning under multiple priors

This paper studies learning under multiple priors by characterizing the decision maker's attitude toward information. She is incredulous if she integrates new information with respect to only those measures that minimizes the likelihood of the new information and credulous if she uses the maximum likelihood procedure to update her priors. Both updating rules expose her to dynamic inconsistency. We explore different ways to resolve this problem. One way consists to assume that the decision maker's attitude toward information is not relevant to characterize conditional preferences. In this case, we show that a necessary and sufficient condition, introduced by [Epstein L. and Schneider M., 2003. Recursive multiple priors. Journal of Economic Theory 113, 1-31], is the rectangularity of the set of priors. Another way is to extend optimism or pessimism to a dynamic set-up. A pessimistic (max-min expected utility) decision maker will be credulous when learning bad news but incredulous when learning good news.Conversely, an optimistic (max-max expected utility) decision maker will be credulous when learning good news but incredulous when learning bad news. It allows max-min (or max-max) expected utility preferences to be dynamically consistent but it violates consequentialism because conditioning works with respect to counterfactual outcomes. The implications of our findings when the set of priors is the core of a non-additive measure are explored.Multiple priors ; Learning ; Dynamic consistency ; Consequentialism ; Attitude toward information

A neural marker for social bias toward in-group accents

Accents provide information about the speaker's geographical, socio-economic, and ethnic background. Research in applied psychology and sociolinguistics suggests that we generally prefer our own accent to other varieties of our native language and attribute more positive traits to it. Despite the widespread influence of accents on social interactions, educational and work settings the neural underpinnings of this social bias toward our own accent and, what may drive this bias, are unexplored. We measured brain activity while participants from two different geographical backgrounds listened passively to 3 English accent types embedded in an adaptation design. Cerebral activity in several regions, including bilateral amygdalae, revealed a significant interaction between the participants' own accent and the accent they listened to: while repetition of own accents elicited an enhanced neural response, repetition of the other group's accent resulted in reduced responses classically associated with adaptation. Our findings suggest that increased social relevance of, or greater emotional sensitivity to in-group accents, may underlie the own-accent bias. Our results provide a neural marker for the bias associated with accents, and show, for the first time, that the neural response to speech is partly shaped by the geographical background of the listener

Updating Choquet Integrals , Consequentialism and Dynamic Consistency

Choquet capacities have been used to represent decision makers’ beliefs in order to generalise the expected utility approach. Conditional capacities have to be defined for dynamic choice situations where information may modify the decision maker future beliefs. Several updating rules have been proposed in the literature. We derive them from a general approach based on conditional Choquet expectations. Conversely, depending on the updating rule adopted, the conditional Choquet integral can take different values. Conditional Choquet Expected Utility are derived from axioms on preferences. However, it is now well-known in decision theory that if preferences satisfy simultaneously dynamic consistency and consequentialism axioms their representation is restricted to classical Expected Utility. We show that the rule proposed by Chateauneuf, Kast and Lapied (2001) is the only one to satisfy dynamic consistency with a nonnecessary additive capacityConditional Choquet expectation; Conditional capacity; Updating rules; Choquet Expected Utility; Dynamic consistency; Consequentialism.