Phenomenology of pseudotensor mesons and the pseudotensor glueball

We study the decays of the pseudotensor mesons $[ \pi_{2}(1670) , K_{2}(1770) , \eta_{2}(1645) , \eta_{2}(1870) ]$ interpreted as the ground-state nonet of $1^1 D_{2}$ $\bar{q}q$ states using interaction Lagrangians which couple them to pseudoscalar, vector, and tensor mesons. While the decays of $\pi_2 (1670)$ and $K_2 (1770)$ can be well described, the decays of the isoscalar states $\eta_2 (1645)$ and $\eta_2 (1870)$ can be brought in agreement with experimental data only if the mixing angle between nonstrange and strange states is surprisingly large (about $-42^\circ$, similar to the mixing in the pseudoscalar sector, in which the chiral anomaly is active). Such a large mixing angle is however at odd with all other conventional quark-antiquark nonets: if confirmed, a deeper study of its origin will be needed in the future. Moreover, the $\bar{q}q$ assignment of pseudotensor states predicts that the ratio $[ \eta_2 (1870) \rightarrow a_2 (1320) \pi]/[\eta_2 (1870) \rightarrow f_2 (1270) \eta]$ is about $23.5$. This value is in agreement with Barberis et al., ($20.4 \pm 6.6$), but disagrees with the recent reanalysis of Anisovich et al., ($1.7 \pm 0.4$). Future experimental studies are necessary to understand this puzzle. If Anisovich's value shall be confirmed, a simple nonet of pseudoscalar mesons cannot be able to describe data (different assignments and/or additional state, such as an hybrid state, will be needed). In the end, we also evaluate the decays of a pseudoscalar glueball into the aforementioned conventional $\bar{q}q$ states: a sizable decay into $K^\ast_2 (1430) K$ and $a_2 (1230) \pi$ together with a vanishing decay into pseudoscalar-vector pairs [such as $\rho(770) \pi$ and $K^\ast (892) K$] are expected. This information can be helpful in future studies of glueballs at the ongoing BESIII and at the future PANDA experiments.Comment: 22 pages (15 main text, 4 appendix, 3 references), 8 tables, 2 figures, v2: more references, additional information and minor changes due to referee comments, published versio

The roles of incentives and voluntary cooperation for contractual compliance

Efficiency under contractual incompleteness often requires voluntary cooperation in situations where self-regarding incentives for contractual compliance are present as well. Here we provide a comprehensive experimental analysis based on the gift-exchange game of how explicit and implicit incentives affect cooperation. We first show that there is substantial cooperation under non-incentive compatible contracts. Incentive-compatible contracts induce best-reply effort and crowd out any voluntary cooperation. Further experiments show that this result is robust to two important variables: experiencing Trust contracts without any incentives and implicit incentives coming from repeated interaction. Implicit incentives have a strong positive effect on effort only under non-incentive compatible contracts.principal-agent games; gift-exchange experiments; incomplete contracts, explicit incentives; implicit incentives; repeated games; separability; experiments

Rifles and Reinforcement: The National Rifle Association’s Partisan Approach to Gun Ownership

The NRA has long been the dominant player in the battle over gun control. Scholars have attributed this dominance in large part to the NRA’s ability to mobilize its membership when necessary. Lacombe (2018) has written of the NRA’s cultivation of a politicized social identity around gun ownership that assists it in doing so. In this thesis, I show that the NRA has tied this gun owner identity to conservatism and to the Republican party. I find that the NRA’s homogenous membership composition advantages it in its strategy of developing a partisan politicized gun-owner identity among its members. The NRA deliberately taps into members’ existing identities in the process of cultivating such an identity. Using Liliana Mason’s (2018) work on identity reinforcement as a framework, I demonstrate that the NRA has much to gain from facilitating the alignment of a gun owner identity with a Republican partisan identity. The alignment of identities tends to strengthen all identities involved, making individuals who hold them more susceptible to action-driving emotions, like enthusiasm and anger. These individuals thus become more likely to engage in politics and are easier to mobilize. With this in mind, I argue that identity reinforcement has been a driving factor in the NRA’s success in overcoming the problem of collective action