Is altruism bad for cooperation?

Some philosophers and social scientists have stressed the importance for good government of an altruistic citizenry that values the well being of one another. Others have emphasized the need for incentives that induce even the self interested to contribute to the public good. Implicitly most have assumed that these two approaches are complementary or at worst additive. But this need not be the case. Behavioral experiments find that if reciprocity-minded subjects feel hostility towards free riders and enjoy inflicting harm on them, near efficient levels of contributions to a public good may be supported when group members have opportunities to punish low contributors. Cooperation may also be supported if individuals are sufficiently altruistic that they internalize the group benefits that their contributions produce. Using a utility function embodying both reciprocity and altruism we show that unconditional altruism towards other members attenuates the punishment motive and thus may reduce the level of punishment inflicted on defectors, resulting in lower rather than higher levels of contributions. Increases in altruism may also reduce the level of benefits from the public project net of contribution costs and punishment costs. The negative effect of altruism on cooperation and material payoffs is greater the stronger is the reciprocity motive among the members. JEL Categories: D64 (altruism); H41 (public goods)public goods, altruism, spite, reciprocity, punishment, cooperation

Social Preferences and Public Economics: Mechanism design when social preferences depend on incentives

Social preferences such as altruism, reciprocity, intrinsic motivation and a desire to uphold ethical norms are essential to good government, often facilitating socially desirable allocations that would be unattainable by incentives that appeal solely to self-interest. But experimental and other evidence indicates that conventional economic incentives and social preferences may be either complements or substitutes, explicit incentives crowding in or crowding out social preferences. We investigate the design of optimal incentives to contribute to a public good under these conditions. We identify cases in which a sophisticated planner cognizant of these non-additive effects would make either more or less use of explicit incentives, by comparison to a naive planner who assumes they are absent. JEL Categories: D52, D64, H21. H41Social preferences, implementation theory, incentive contracts, incomplete contracts, framing, motivational crowding out, ethical norms, constitutions

Searching for Dark Photons with Maverick Top Partners

In this paper, we present a model in which an up-type vector-like quark (VLQ) is charged under a new $U(1)_d$ gauge force which kinetically mixes with the SM hypercharge. The gauge boson of the $U(1)_d$ is the dark photon, $\gamma_d$. Traditional searches for VLQs rely on decays into Standard Model electroweak bosons $W,Z$ or Higgs. However, since no evidence for VLQs has been found at the Large Hadron Collider (LHC), it is imperative to search for other novel signatures of VLQs beyond their traditional decays. As we will show, if the dark photon is much less massive than the Standard Model electroweak sector, $M_{\gamma_d}\ll M_Z$, for the large majority of the allowed parameter space the VLQ predominately decays into the dark photon and the dark Higgs that breaks the $U(1)_d$ . That is, this VLQ is a `maverick top partner' with nontraditional decays. One of the appeals of this scenario is that pair production of the VLQ at the LHC occurs through the strong force and the rate is determined by the gauge structure. Hence, the production of the dark photon at the LHC only depends on the strong force and is largely independent of the small kinetic mixing with hypercharge. This scenario provides a robust framework to search for a light dark sector via searches for heavy colored particles at the LHC.Comment: 40 pages and 11 figure

Optical SETI at Harvard-Smithsonian

A high-intensity pulsed laser, teamed with a moderate sized transmitting telescope, forms an efficient interstellar beacon. To a distant observer in the direction of its slender beam, such a laser transmitter, built with "Earth 2000" technology only, would appear (during its brief pulse) a thousand times brighter than our sun in broadband visible light; even at ranges of 1000 light years a single nanosecond laser pulse would deliver roughly a thousand photons to a 10-meter receiving telescope. We have built a photometer to search for such unresolved pulses, and are using it in a piggyback targeted search of some 2500 nearby solar-type stars. The photometer receives about 1/3 of the light focused by the 1.5-meter optical reflector, otherwise unused by the primary experiment (a stellar radial-velocity survey). A beamsplitter followed by a pair of fast hybrid avalanche detectors is triggered in coincidence to record the time and intensity profile of large pulses. In the first year of operation the system has made ~8500 observations of ~2500 separate stellar candidates, amounting to 50 days of cumulative observation time. We review those observations, and suggest follow-on experiments

Comprehensive force field for multiply-chlorinated hydrocarbons

A force field is presented that has been optimized for chlorinated hyrocarbons containing isolated, vicinal, and geminal secondary chlorines. For carbon--chlorine stretch modes, 74 frequencies in 10 molecules are reproduced with an average error of 4.5 cm-. This force field can therefore serve to study these conformation-dependent modes in multiply-chlorinated hydrocarbons.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28955/1/0000792.pd

Vibrational analysis of 2,2,3-trichlorobutane and a force field for 2,2-dichloropropane

The infrared and Raman spectra of 2,2,3-dichlorobutane have been analysed in terms of normal modes calculated from a force field for secondary dichlorides refined using this molecule as well as 2,2-dichlorobutane and 2,2-dichloropropane. A force field specific to the latter molecule is presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28954/1/0000791.pd

Vibrational analysis of 2,3,4-trichloropentanes

One meso form and the racemic isomer of 2,3,4-trichloropentane have been synthesized, and their infrared and Raman spectra analysed on the basis of a general force field refined for multiply-chlorinated hydrocarbons. Previous results on 2,3-dichlorobutane have been incorporated in this study, thus providing a force field for detailed analyses of vicinally-chlorinated hydrocarbons.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28952/1/0000789.pd