Early-data measurement of J/ψ → μ+μ− decays with the ATLAS detector at LHC

The approach for the observation of the first J/ψ → μ+μ− production using the ATLAS detector at the Large Hadron Collider will be presented. Given the large quarkonia cross sections, large sample of muons can be obtained with few pb−1. These clear muon samples can be used to study the Muon Spectrometer in all his aspects, like detector alignment, trigger calibration and trigger efficiency. Events of interest can be triggered by requiring one or two isolated muons; offline selection can then be applied, consisting maily of muon pseudorapidity cuts and lepton transverse-momentum threshold

Search for the rare decay Bs → μ+μ− with ATLAS

An overview of the search for the rare decay Bs → μ+μ− with the ATLAS detector at Large Hadron Collider is presented. The analysis, based on 2.4 fb−1 of integrated luminosity, has been performed by using a multivariate, multi-bin selection method. A 95% CL upper limit on the branching fraction of the process has been set at BR (Bs → μ+μ−) ≤ 2.2 10−8

Search for supersymmetry at ATLAS

These proceedings summarize the searches for Supersymmetry (SUSY) with the ATLAS detector at the Large Hadron Collider (LHC), focusing on the results obtained with the full proton-proton collisions data set recorded at a center-of-mass energy of √s = 8TeV, corresponding to an integrated luminosity of approximately 20 fb−1. Various searches were carried out in order to explore a large variety of production models and the results matched the Standard Model background expectation, therefore exclusion limits were derived on the production of new physics

Do Shareholders' Preferences Affect their Funds' Management? Evidence from the Cross Section of Shareholders and Funds

We consider how fund managers respond to the conflicting preferences of their investors. We focus on the conflict between the taxable and retirement accounts of international funds, which face different tradeoffs between dividends and capital gains. In principle, managers could resolve this conflict through dividend arbitrage, but a proprietary database of dividend-arbitrage transactions shows that in practice they cannot. Thus, managers must resolve it through their investment policies, and we find robust evidence that managers with more retirement money favor the preferences of retirement investors. We find additional evidence in the difference between U.S. and Canadian funds' portfolio weights. Nous étudions comment les gestionnaires de fonds réagissent aux préférences contradictoires de leurs investisseurs. Notre étude se concentre principalement sur les conflits entre les comptes taxés et les comptes de retraite des fonds internationaux qui font l'objet de compromis différents entre les gains en dividendes et les gains de capital. En théorie, les gestionnaires peuvent résoudre ces conflits par des opérations d'arbitrage sur les dividendes, mais une base de données privée d'opérations d'arbitrage fait apparaître qu'en pratique ils ne peuvent pas. Les gestionnaires doivent alors résoudre ces conflits à travers leurs politiques d'investissement, et nous trouvons des résultats significatifs montrant que ceux dont le capital est issu majoritairement des retraites favorisent les investisseurs de fonds de pension. Nous trouvons également des différences entre les poids des portefeuilles de fonds américains et canadiens.Dividend arbitrage, tax efficiency, agency issues, mutual funds, arbitrage sur les dividendes, taxes sur les rendements, placements pour compte, fonds commun de placement

How and Why do Investors Trade Votes, and What Does it Mean?

The standard analysis of corporate governance is that shareholders vote in the ratios that firms choose, such as one-share-one-vote. But if the cost of unbundling and trading votes is sufficiently low, then shareholders vote in the ratios that they themselves choose. We document an active market for votes within the equity-loan market, where we find that the average vote sells for zero. We hypothesize that asymmetric information motivates these vote reallocations, and we find support for this view in the cross section of votes: there is more trade for higher-spread firms and more for poor performers, especially when the vote is close. We also find that the vote reallocations correspond to support for shareholder proposals and opposition to management proposals. L'analyse classique de la gouvernance d'entreprise suppose que les actionnaires votent selon les modalités choisies par la firme, par exemple un vote par action. Mais si les coûts associés à la séparation et à l'échange des votes sont suffisamment faibles, alors les actionnaires votent selon les modalités qu'ils ont eux-mêmes choisies. Nous présentons le cas d'un marché actif de votes au sein du marché des mises de fonds sous forme d'emprunts (equity loans), où nous constatons qu'en moyenne les votes se vendent pour rien. Nous supposons que l'asymétrie d'information provoque cette réallocation des votes, et nous étayons cette hypothèse à travers l'étude transversale des votes : le nombre d'opérations est plus important pour les compagnies dont l'écart acheteur-vendeur est plus élevé ainsi que pour celles dont les résultats sont plus faibles, particulièrement lorsque le vote est clos. Cette étude montre aussi que la réallocation des votes permet de soutenir les propositions des actionnaires et de s'opposer à celles des gestionnaires.vote trading, corporate governance, equity lending, information asymmetry, transaction de votes, gouvernance d'entreprise, prêt d'actions, asymétrie d'information

Evidence on the Efficacy of School-Based Incentives for Healthy Living

We analyze the effects of a school-based incentive program on children's exercise habits. The program offers children an opportunity to win prizes if they walk or bike to school during prize periods. We use daily child-level data and individual fixed effects models to measure the impact of the prizes by comparing behavior during prize periods with behavior during non-prize periods. Variation in the timing of prize periods across different schools allows us to estimate models with calendardate fixed effects to control for day-specific attributes, such as weather and proximity to holidays. On average, we find that being in a prize period increases riding behavior by sixteen percent, a large impact given that the prize value is just six cents per participating student. We also find that winning a prize lottery has a positive impact on ridership over subsequent weeks; consider heterogeneity across prize type, gender, age, and calendar month; and explore differential effects on the intensive versus extensive margins.health; exercise; children; school; incentives; active commuting

On Interferometric Duality in Multibeam Experiments

We critically analyze the problem of formulating duality between fringe visibility and which-way information, in multibeam interference experiments. We show that the traditional notion of visibility is incompatible with any intuitive idea of complementarity, but for the two-beam case. We derive a number of new inequalities, not present in the two-beam case, one of them coinciding with a recently proposed multibeam generalization of the inequality found by Greenberger and YaSin. We show, by an explicit procedure of optimization in a three-beam case, that suggested generalizations of Englert's inequality, do not convey, differently from the two-beam case, the idea of complementarity, according to which an increase of visibility is at the cost of a loss in path information, and viceversa.Comment: 26 pages, 1 figure, substantial changes in the text, new material has been added in Section 3. Version to appear in J.Phys.

Personalized Recommendation of PoIs to People with Autism

The suggestion of Points of Interest to people with Autism Spectrum Disorder (ASD) challenges recommender systems research because these users' perception of places is influenced by idiosyncratic sensory aversions which can mine their experience by causing stress and anxiety. Therefore, managing individual preferences is not enough to provide these people with suitable recommendations. In order to address this issue, we propose a Top-N recommendation model that combines the user's idiosyncratic aversions with her/his preferences in a personalized way to suggest the most compatible and likable Points of Interest for her/him. We are interested in finding a user-specific balance of compatibility and interest within a recommendation model that integrates heterogeneous evaluation criteria to appropriately take these aspects into account. We tested our model on both ASD and "neurotypical" people. The evaluation results show that, on both groups, our model outperforms in accuracy and ranking capability the recommender systems based on item compatibility, on user preferences, or which integrate these two aspects by means of a uniform evaluation model

Neutralino spin measurement with ATLAS detector at LHC

Minimal Supergravity (mSUGRA) [1] Supersimmetry breaking mechanism is a leading candidate for yielding new physics beyond the Standard Model (SM). Within mSUGRA framework masses, mixings and decays of all SUSY and Higgs particles are determined in terms of four input parameters and a sign: the common mass m 0 of scalar particles at the grand unification scale, the common fermion mass m 1/2, the common trilinear coupling A 0, the ratio of the Higgs vacuum expectation values tan β and the sign of the supersymmetric Higgs mass parameter μ. Once a signal of a physics beyond the Standard Model is seen at LHC, it will be fundamental to measure properties of new particles, like spin, in order to prove that they are indeed supersymmetric partners. The present work [2] is based on the spin analysis method proposed in [3] and allows the discrimination of different hypotheses for spin assignments. Some studies [4, 5] show that this method can also be used for the discrimination of SUSY from an Universal Extra Dimensions model which can mimick low energy SUSY at hadron colliders. In this report two selected points inside stau-coannihilation and bulk regions of the allowed mSUGRA parameter space are considered. Fast simulation [6] of the ATLAS detector was performed in order to investigate the feasibility of supersymmetric particles’ spin measurement