Analyticity and the Isgur-Wise Function

We reconsider the recent derivation by de Rafael and Taron of bounds on the slope of the Isgur-Wise function. We argue that one must be careful to include cuts starting below the heavy meson pair production threshold, arising from heavy quark-antiquark bound states, and that if such cuts are properly accounted for then no constraints may be derived.Comment: 8 pages, uses harvmac, SLAC-PUB-5956, UCSD/PTH 92-35, CALT-68-183

LIBOR Phaseout: Litigation is Coming

This paper will explore the different steps market participants should take to make sure they are prepared when LIBOR is phased out in December 2021. Part I will focus on the actions market participants should do before going into negotiations that can increase their potential to reach a consensual agreement. Part II will explore what financial firms should be prepared for during the negotiation process and what claims may arise when no agreement is reached. The decision for how to handle any LIBOR-linked financial instrument in their portfolio should be left to the discretion of market participants themselves. This paper does not set out to make that decision, but it will communicate the urgency with which firms should act to either reach a consensual agreement or prepare for the legal risk and litigation costs of DEFCON 1

Long-Distance Dominance of the CP Asymmetry in B->X_{s,d}+gamma Decays

We show that in the Standard Model the parametrically leading (by a factor 1/alpha_s) contribution to the inclusive CP asymmetry in B->X_{s,d}+gamma decays arises from a long-distance effect in the interference of the electromagnetic dipole amplitude with the amplitude for an up-quark penguin transition accompanied by soft gluon emission. This contribution is governed by a single hadronic parameter Lambda_{17}^u related to a matrix elements of a non-local operator. In view of current experimental data, a future precision measurement of the flavor-averaged CP asymmetry in B->X_s+gamma will signal the presence of new physics only if a value below -2% is found. A cleaner probe of new physics is offered by the difference of the CP asymmetries in charged versus neutral B-meson decays.Comment: 4 page

The Residual Mass Term in the Heavy Quark Effective Theory

We reformulate the heavy quark effective theory in the presence of a residual mass term, which has been taken to vanish in previous analyses. While such a convention is permitted, the inclusion of a residual mass allows us to resolve a potential ambiguity in the choice of the expansion parameter which defines the effective theory. We show to subleading order in the mass expansion that physical quantities computed in the effective theory do not depend on the expansion parameter.Comment: 14 page

An Exploratory Lattice Study of Spectator Effects in Inclusive Decays of the Lambda_b Baryon

A possible explanation of the apparent disrepency between the theoretical prediction and experimental measurement of the ratio of lifetimes $\tau(\Lambda_b)/\tau(B_d)$ is that ``spectator effects'', which appear at $O(1/m_b^3)$ in the heavy quark expansion, contribute significantly. We investigate this possibility by computing the corresponding operator matrix elements in a lattice simulation. We find that spectator effects are indeed significant, but do not appear to be sufficiently large to account for the full discrepency. We stress, however, that this is an exploratory study, and it is important to check our conclusions on a larger lattice and using a larger sample of gluon configurations.Comment: 12 pages, Latex. One correction: in the original version of the paper, in eqs.10, 11, 12 and 39, the values of the pion masses appeared interchange

Extracting ∣Vbc∣|V_{bc}|, mcm_c and mbm_b from Inclusive DD and BB Decays

Using recent results for nonperturbative contributions to the $B$ and $D$ meson inclusive semileptonic widths, a model independent extraction of \vbc, $m_c$ and $m_b$ is made from the experimentally measured $B$ and $D$ lifetimes and semileptonic branching ratios. Constraining the parameters of the HQET at \CO(1/m_Q^2) by the $D$ semileptonic width, \vbc is found to lie in the range .040<\vbc< 0.057. The $c$ and $b$ quark masses are not well constrained due to uncertainty in the relevant scale of $\alpha_s$. These results assume the validity of perturbative QCD at the low scales relevant to semileptonic charm decay. Without making this assumption, somewhat less stringent bounds on $V_{bc}$ from $B$ decay alone may be obtained.Comment: (revised version - contains a more detailed discussion of the uncertainty in our results from the uncertainty in the scale of \alpha_s) 12 pages, 5 figures included, uses harvmac.tex and epsf.tex, UCSD/PTH 93-25, UTPT 93-21, CMU-HEP 93-1

Using RSS to Improve Web Harvest Results for News Web Sites

In the last several years, the Library of Congress Web archiving program has grown to include large sites that publish news–over more than a year we learned they present serious challenges. After thinking through the use cases for archived online news sites, we realized that completeness of harvest was paramount. As we developed our understanding of deficiencies in the completeness of these kinds of sites we began to test use of RSS feeds to build customized seed lists for shallow crawls as the primary way these sites are crawled. Over time we discovered that while completeness of harvest was greatly improved, we had a new problem with the ability to browse to all harvested content. This article is a case study describing these iterative experiences that are a work in progress

Economically optimal marine reserves without spatial heterogeneity in a simple two-patch model

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Natural Resource Modeling 28 (2015): 244-255, doi:10.1111/nrm.12066.Bioeconomic analyses of spatial fishery models have established that marine reserves can be economically optimal (i.e., maximize sustainable profit) when there is some type of spatial heterogeneity in the system. Analyses of spatially continuous models and models with more than two discrete patches have also demonstrated that marine reserves can be economically optimal even when the system is spatially homogeneous. In this note we analyze a spatially homogeneous two-patch model and show that marine reserves can be economically optimal in this case as well. The model we study includes the possibility that fishing can damage habitat. In this model, marine reserves are necessary to maximize sustainable profit when dispersal between the patches is sufficiently high and habitat is especially vulnerable to damage.Graduate Research Fellowship and a Postdoctoral Research Fellowship in Biology Grant Number: DBI-1401332; US National Science Foundation Grant Numbers: OCE-1031256, DEB-1257545, DEB-11450172016-06-2

Habitat damage, marine reserves, and the value of spatial management

Author Posting. © Ecological Society of America, 2013. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 23 (2013): 959–971, doi:10.1890/12-0447.1.The biological benefits of marine reserves have garnered favor in the conservation community, but “no-take” reserve implementation is complicated by the economic interests of fishery stakeholders. There are now a number of studies examining the conditions under which marine reserves can provide both economic and ecological benefits. A potentially important reality of fishing that these studies overlook is that fishing can damage the habitat of the target stock. Here, we construct an equilibrium bioeconomic model that incorporates this habitat damage and show that the designation of marine reserves, coupled with the implementation of a tax on fishing effort, becomes both biologically and economically favorable as habitat sensitivity increases. We also study the effects of varied degrees of spatial control on fisheries management. Together, our results provide further evidence for the potential monetary and biological value of spatial management, and the possibility of a mutually beneficial resolution to the fisherman–conservationist marine reserve designation dilemma.M. G. Neubert acknowledges the support of the National Science Foundation (DMS-0532378, OCE-1031256) and a Thomas B. Wheeler Award for Ocean Science and Society. H. V. Moeller acknowledges support from a National Science Foundation Graduate Research Fellowship. This research is based in part on work supported by Award No. USA 00002 made by King Abdullah University of Science and Technology (KAUST)

U-Spin Symmetry in Charmless B Decays

We prove a general theorem about equal CP rate differences within pairs of U-spin related charmless $B$ and $B_s$ decays. Large deviations from equalities would be evidence for new physics. Six pairs of decays into two pseudoscalar mesons are identified where such relations hold. Ratios of corresponding rate differences and certain ratios of rates measure U-spin breaking. These processes provide useful information on the weak phase $\gamma={\rm Arg} V^*_{ub}$. Applications of U-spin symmetry to other decays are discussed.Comment: A few typos corrected, to appear in Phys. Lett.