The recently confirmed neutron-shell closure at N=32 has been investigated for the first time below the magic proton number Z=20 with mass measurements of the exotic isotopes (52,53)K, the latter ...being the shortest-lived nuclide investigated at the online mass spectrometer ISOLTRAP. The resulting two-neutron separation energies reveal a 3 MeV shell gap at N=32, slightly lower than for 52Ca, highlighting the doubly magic nature of this nuclide. Skyrme-Hartree-Fock-Bogoliubov and ab initio Gorkov-Green function calculations are challenged by the new measurements but reproduce qualitatively the observed shell effect.
This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at sqrts_{NN}=5.02 TeV. The analysis is conducted using a data sample corresponding to an ...integrated luminosity of 1.73 nb^{-1}, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy E_{T}^{γ}>3 GeV and pseudorapidity |η_{γ}|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events over the expected background has a significance of 8.2 standard deviations. The measured fiducial cross section is 78±13(stat)±7(syst)±3(lumi) nb.
Types of Contact Lowe, Matt
The American economic review,
06/2021, Letnik:
111, Številka:
6
Journal Article
Recenzirano
Odprti dostop
I estimate the effects of collaborative and adversarial intergroup contact. I randomly assigned Indian men from different castes to participate in cricket leagues or to serve as a control group. ...League players faced variation in collaborative contact, through random assignment to homogeneous-caste or mixed-caste teams, and adversarial contact, through random assignment of opponents. Collaborative contact increases cross-caste friendships and efficiency in trade, and reduces own-caste favoritism. In contrast, adversarial contact generally reduces cross-caste interaction and efficiency. League participation reduces intergroup differences, suggesting that the positive aspects of intergroup contact more than offset the negative aspects in this setting.
Short-run subsidies for health products are common in poor countries. How do they affect long-run adoption? A common fear among development practitioners is that one-off subsidies may negatively ...affect long-run adoption through reference-dependence: People might anchor around the subsidized price and be unwilling to pay more for the product later. But for experience goods, one-off subsidies could also boost long-run adoption through learning. This paper uses data from a two-stage randomized pricing experiment in Kenya to estimate the relative importance of these effects for a new, improved antimalarial bed net. Reduced form estimates show that a one-time subsidy has a positive impact on willingness to pay a year later inherit. To separately identify the learning and anchoring effects, we estimate a parsimonious experience-good model. Estimation results show a large, positive learning effect but no anchoring. We black then discuss the types of products and the contexts inherit for which these results may apply.
Electron-Ion Collider: The next QCD frontier Accardi, A.; Albacete, J. L.; Anselmino, M. ...
The European physical journal. A, Hadrons and nuclei,
2016/9, Letnik:
52, Številka:
9
Journal Article
Recenzirano
Odprti dostop
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This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader ...nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics over the past decades and, in particular, the focused ten-week program on “Gluons and quark sea at high energies” at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them. It has been benefited profoundly from inputs by the users’ communities of BNL and JLab. This White Paper offers the promise to propel the QCD science program in the US, established with the CEBAF accelerator at JLab and the RHIC collider at BNL, to the next QCD frontier.
A search for heavy Majorana neutrinos produced in the B- → π+ μ- μ- decay mode is performed using 3 fb(-1) of integrated luminosity collected with the LHCb detector in pp collisions at ...center-of-mass energies of 7 and 8 TeV at the LHC. Neutrinos with masses in the range 250 to 5000 MeV and lifetimes from zero to 1000 ps are probed. In the absence of a signal, upper limits are set on the branching fraction B(B- → π+ μ- μ-) as functions of neutrino mass and lifetime. These limits are on the order of 10(-9) for short neutrino lifetimes of 1 ps or less. Limits are also set on the coupling between the muon and a possible fourth-generation neutrino.
Fairness and cheating Houser, Daniel; Vetter, Stefan; Winter, Joachim
European economic review,
11/2012, Letnik:
56, Številka:
8
Journal Article
Recenzirano
We present evidence from a laboratory experiment showing that individuals who believe they were treated unfairly in an interaction with another person are more likely to cheat in a subsequent ...unrelated game. Specifically, subjects first participated in a dictator game. They then flipped a coin in private and reported the outcome. Subjects could increase their total payoff by cheating, i.e., lying about the outcome of the coin toss. We found that subjects were more likely to cheat in reporting the outcome of the coin flip when: (1) they received either nothing or a very small transfer from the dictator; and (2) they claimed to have been treated unfairly.
► Participants first participated in a dictator game. ► They then flipped a coin in private and reported the outcome. ► Participants could increase their total payoff by lying about the outcome of the coin toss. ► Participants who felt unfairly treated in the Dictator game were more likely to lie.
Online labor markets have great potential as platforms for conducting experiments. They provide immediate access to a large and diverse subject pool, and allow researchers to control the experimental ...context. Online experiments, we show, can be just as valid—both internally and externally—as laboratory and field experiments, while often requiring far less money and time to design and conduct. To demonstrate their value, we use an online labor market to replicate three classic experiments. The first finds quantitative agreement between levels of cooperation in a prisoner’s dilemma played online and in the physical laboratory. The second shows—consistent with behavior in the traditional laboratory—that online subjects respond to priming by altering their choices. The third demonstrates that when an identical decision is framed differently, individuals reverse their choice, thus replicating a famed Tversky-Kahneman result. Then we conduct a field experiment showing that workers have upward-sloping labor supply curves. Finally, we analyze the challenges to online experiments, proposing methods to cope with the unique threats to validity in an online setting, and examining the conceptual issues surrounding the external validity of online results. We conclude by presenting our views on the potential role that online experiments can play within the social sciences, and then recommend software development priorities and best practices.
The dependence of $\mathrm{f}_{0}$(980) production on the final-state charged-particle multiplicity in p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV is reported. The production of ...$\mathrm{f}_{0}$(980) is measured with the ALICE detector via the $\mathrm{f}_0 (980) \rightarrow \pi^{+}\pi^{-}$ decay channel in a midrapidity region of $-0.5<y<0$. Particle yield ratios of $\mathrm{f}_{0}$(980) to $\pi$ and $\mathrm{K}^{*}$(892)$^{0}$ are found to be decreasing with increasing charged-particle multiplicity. The magnitude of the suppression of the $\mathrm{f}_{0}$(980)/$\pi$ and $\mathrm{f}_{0}$(980)/$\mathrm{K}^{*}$(892)$^{0}$ yield ratios is found to be dependent on the transverse momentum $p_{\mathrm{T}}$, suggesting different mechanisms responsible for the measured effects. Furthermore, the nuclear modification factor $Q_{\mathrm{pPb}}$ of $\mathrm{f}_{0}$(980) is measured in various multiplicity ranges. The $Q_{\mathrm{pPb}}$ shows a strong suppression of the $\mathrm{f}_{0}$(980) production in the $p_{\mathrm{T}}$ region up to about 4 GeV/$c$. The results on the particle yield ratios and $Q_{\mathrm{pPb}}$ for $\mathrm{f}_{0}$(980) may help to understand the late hadronic phase in p$-$Pb collisions and the nature of the internal structure of $\mathrm{f}_{0}$(980) particle.
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