Coupling QCD-scale axion-like particles to gluons

We present a novel data-driven method for determining the hadronic interaction strengths of axion-like particles (ALPs) with QCD-scale masses. Using our method, it is possible to calculate the hadronic production and decay rates of ALPs, along with many of the largest ALP decay rate to exclusive final states. To illustrate the impact on QCD-scale ALP phenomenology, we consider the scenario where the ALP-gluon coupling is dominant over the ALP coupling to photons, electroweak bosons, and all fermions for $m_{\pi} \lesssim m_a \lesssim 3$ GeV. We emphasize, however, that our method can easily be generalized to any set of ALP couplings to SM particles. Finally, using the approach developed here, we provide calculations for the branching fractions of $\eta_c \to VV$ decays, i.e. $\eta_c$ decays into two vector mesons, which are consistent with the known experimental values.Comment: 19 pages, 7 figures; v3 Fig 4 updated to account for a small change in the limit taken from [1903.03586

Υ\Upsilon and ψ\psi leptonic decays as probes of solutions to the RD(∗)R_D^{(*)} puzzle

Experimental measurements of the ratios $R(D^{(*)})\equiv\frac{\Gamma(B\to D^{(*)}\tau\nu)}{\Gamma(B\to D^{(*)}\ell\nu)}$ ($\ell=e,\mu$) show a $3.9\sigma$ deviation from the Standard Model prediction. In the absence of light right-handed neutrinos, a new physics contribution to $b\to c\tau\nu$ decays necessarily modifies also $b\bar b\to\tau^+\tau^-$ and/or $c\bar c\to\tau^+\tau^-$ transitions. These contributions lead to violation of lepton flavor universality in, respectively, $\Upsilon$ and $\psi$ leptonic decays. We analyze the constraints resulting from measurements of the leptonic vector-meson decays on solutions to the $R(D^{(*)})$ puzzle. Available data from BaBar and Belle can already disfavor some of the new physics explanations of this anomaly. Further discrimination can be made by measuring $\Upsilon(1S,2S,3S)\to\tau\tau$ in the upcoming Belle II experiment.Comment: Version published in JHEP, 17 pages, 7 figure

Pluralizing the Sharing Economy

The so-called “sharing” economy presents one of the most important and controversial regulatory dilemmas of our time—yet, surprisingly, it remains undertheorized. This Article supplies needed analysis. Specifically, the Article offers a regulatory model that distinguishes between two separate kinds of transactions: conventional economic transactions and those that rely on temporary access to goods and services that would otherwise go underutilized (what I call “access-to-excess” transactions). The regulatory regime that this Article proposes would distinguish between true access-to-excess transactions and conventional transactions. The model is rooted in a version of pluralist theory that posits that the state is responsible for cultivating a range of social institutions that offer meaningful economic and social alternatives to individuals. Recognizing access-to-excess transactions in a separate legal regime does not mean countenancing all access-to-excess activity in an under-regulated Wild West of markets. Pluralism has something to offer here as well: I argue that, properly understood, pluralistic principles do not endorse free-market and hands-off policies. Rather, they require state intervention to preserve existing choices, embed and balance diverse values (not only autonomy), ensure fair competition, and protect consumers and employees from strategic and opportunistic behaviors. Thus, pluralistic principles offer the normative foundation for inventive regulation—neither conventional nor free market—that can restrain some of the “sharing” economy’s harms without impeding innovation. Finally, the Article reverses the lens: The “sharing” economy serves as a real-life laboratory to reveal the operation of pluralistic theory and, thus, sheds light on the theory’s limitations. In particular, the “sharing” economy shows how the plasticity of pluralistic theory may enable harmful free-market policies to masquerade as “choice.

First Comes Marriage, Then Comes Baby, Then Comes What Exactly?

Taiwan’s legalization of same-sex marriage is an event of international importance concerning the rights of LGBTQ+ individuals and partners; further, it constitutes an opportunity to examine the state of LGBTQ+ equality in Taiwan and elsewhere. To this end, through theoretical and comparative lenses, this Article asks what equality for LGBTQ+ means and what comes after marriage. It offers perspectives on the past, present, and future of the intersection of same-sex marriage and equality. Looking at the path to same-sex marriage in Taiwan, the Article argues that the Taiwanese Constitutional Court’s ruling legalizing same-sex marriage maintained a line between domesticated liberty for LGBTQ+ people, on the one hand, and limits on that population’s liberty to form families, on the other. The law that implemented the ruling kept this tension; hence, it enfolds discrimination against LGBTQ+ individuals, especially in the area of family formation. But Taiwan is not exceptional in holding onto parentage discrimination after legalization of same-sex marriage. The European perspective teaches that discrimination in parentage remains after legalization but disappears over time. Experience from elsewhere also clarifies that the fight for equal parental rights can be difficult, and that much opposition to LGBTQ+ equality is embedded in biases related to LGBTQ+ parenting and in racism. Finally, moving to explore future paths to parity, the Article contends that, for various reasons including those indicated above, marriage cannot serve as the final frontier of LGBTQ+ equality. Substantive equality in Taiwan requires, at the least, the repeal of adultery as a grounds for divorce and for civil remedies. A broader view of equality and autonomy also warrants adopting a regime in which marriage is not the only mechanism to access rights and benefits that are linked to relationships of interdependency. Likewise, creating more options for legal recognition of relationships is imperative for individuals in diverse types of relationships, and for LGBTQ+ individuals in particular. Lastly, the Article suggests that discrimination that currently exists in the area of obligations toward parents-in-law has a liberating aspect. The Taiwanese experience is a teaching moment for LGBTQ+ movements and scholars around the globe. It calls on other scholars to avoid generalizations in framing paths to liberty and equality by being sensitive to local differences, and to reconsider the place of marriage as the golden standard of LGBTQ+ equality

Registering Relationships

Despite the dramatic changes in family structure in the past decades — including the unprecedented and skyrocketing number of families who live in non-marital arrangements — marriage and marriage-mimic institutions remain the only legal options for the recognition of relationships. This regulatory regime leaves millions of Americans without the means to establish and protect relationship rights. The article suggests that the legal issues arising from non-marital relationships would be best addressed if more options for legal recognition of such relationships were offered. Accordingly, this article presents the primary principles of a registration-based marriage alternative, founded on contract: “registered contractual relationships.” This legal institution would offer couples the option to sign — and deposit with the state registrar — a contract defining the partners’ obligations and rights vis-à-vis one another and changing their status to that of “registered partners.” Registered partners would receive most of the rights and benefits that the state provides for married couples. Registration would not require a solemnization process nor any ceremonial or religious component and would provide an easy way to dissolve relationships in cases where couples do not have minor children. This model enjoys the flexibility of contracts and the certainty of official registration. It promotes greater autonomy in family formation in two ways: it allows more choice among state-sanctioned mechanisms; and it allows people to design the terms of their relationships, rather than imposing the one-size-fits-all structure of marriage. The introduction of registered contractual relationships would have far-reaching legal and societal consequences. It would provide a functional model for registration and termination of partnerships, offer an alternative that is free of (and reduces) the harmful symbolism of marriage, and accommodate a wide range of family structures. At the same time, it would efficiently address the state’s need to regulate some aspects of relationships in the interest of avoiding and mediating conflict and of encouraging couples to think about and negotiate their rights early in their relationships. The article also looks at the success of the French PACS — a model that resembles registered contractual relationships and provides important lessons to the United States