35 research outputs found
Discrete power law with exponential cutoff and Lotka's law
No full textOne of the first bibliometric laws appeared in Alfred J. Lotka\u27s 1926 examination of author productivity in chemistry and physics. The result was a productivity distribution described by a power law. In this paper, Lotka\u27s original data on author productivity in chemistry are reconsidered. We define a discrete power law with exponential cutoff, test Lotka\u27s data, and compare the fit to the discrete power law
Poster for Goldfadn's operetta Bar Kochba, Romania
No full textBar Kokhba, by the celebrated author Goldfaden. Romanian poster. Printed by Libraria Smolinsky. Advertisement for a benefit performance of a Goldfaden operetta by Group Tikvas Kanada (Hope of Canada) from Paşcani (now in Romania) to raise funds for "two hundred starving people on their way to the Land of Israel.”Digital imagedigitize
Impact of a resonance on thermal targets for invisible dark photon searches
No full textDark photons in the MeV to GeV mass range are important targets for
experimental searches. We consider the case where dark photons decay
invisibly to hidden dark matter through . For generic masses,
proposed accelerator searches are projected to probe the thermal target region
of parameter space, where the particles annihilate through in the early universe and freeze out with the correct relic density.
However, if , dark matter annihilation is resonantly
enhanced, shifting the thermal target region to weaker couplings. For degeneracies, we find that the annihilation cross section is generically
enhanced by four (two) orders of magnitude for scalar (pseudo-Dirac) dark
matter. For such moderate degeneracies, the thermal target region drops to weak
couplings beyond the reach of all proposed accelerator experiments in the
scalar case and becomes extremely challenging in the pseudo-Dirac case.
Proposed direct detection experiments can probe moderate degeneracies in the
scalar case. For greater degeneracies, the effect of the resonance can be even
more significant, and both scalar and pseudo-Dirac cases are beyond the reach
of all proposed accelerator and direct detection experiments. For scalar dark
matter, we find an absolute minimum that sets the ultimate experimental
sensitivity required to probe the entire thermal target parameter space, but
for pseudo-Dirac fermions, we find no such thermal target floor
Poster for Goldfadn's operetta Bar Kochba, Romania
No full textBar Kokhba, by the celebrated author Goldfaden. Romanian poster. Printed by Libraria Smolinsky. Advertisement for a benefit performance of a Goldfaden operetta by Group Tikvas Kanada (Hope of Canada) from Paşcani (now in Romania) to raise funds for "two hundred starving people on their way to the Land of Israel.”Digital imagedigitize
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Towards the Detection of an Abelian Dark Sector
No full textDark matter remains the foremost sign of particle physics beyond the Standard Model. Little is known about its microscopic properties, but there are compelling astrophysical and cosmological reasons to believe that it resides in a ``dark sector'' with its own forces, and with weak coupling to the Standard Model. One popular theory which may explain these dark matter interactions is known as the ``kinetic mixing portal'' wherein a ``dark photon'' of a new abelian gauge symmetry is induced to mix with the Standard Model photon, and thus to mediate interactions with the visible sector. In this dissertation we will examine the phenomenology of this theory. As dark matter travels through the galaxy it may scatter off of nuclei through dark photon exchange, losing enough energy to become gravitationally trapped and accumulate in astrophysical bodies. We propose and examine in detail a search for the dark photons radiated by this trapped population of dark matter in Chapters 2, 3, and 4, finding that there are viable regions of parameter space that cannot be probed by direct detection but would be amenable to discovery by this search. In Chapter 5 we perform a detailed calculation of the dark matter abundance in theories where dark matter annihilates through the kinetic mixing portal. We find that the reach of current dark photon search experiments are remarkably sensitive to the mass of the dark photon near resonance and place an absolute lower limit on the thermal relic parameters of scalar dark matter coupled to a dark photon
Erratum: Dark photons from captured inelastic dark matter annihilation: Charged particle signatures [Phys. Rev. D <b>95</b> , 075015 (2017)]
No full textDark photons from captured inelastic dark matter annihilation: Charged particle signatures
No full textPoster for Goldfadn's operetta Bar Kochba, Romania
No full textBar Kokhba, by the celebrated author Goldfaden. Romanian poster. Printed by Libraria Smolinsky. Advertisement for a benefit performance of a Goldfaden operetta by Group Tikvas Kanada (Hope of Canada) from Paşcani (now in Romania) to raise funds for "two hundred starving people on their way to the Land of Israel.”Digital imagedigitize
Co-author Weighting in Bibliometric Methodology and Subfields of a Scientific Discipline
No full textAbstract Purpose To give a theoretical framework to measure the relative impact of bibliometric methodology on the subfields of a scientific discipline, and how that impact depends on the method of evaluation used to credit individual scientists with citations and publications. The authors include a study of the discipline of physics to illustrate the method. Indicators are introduced to measure the proportion of a credit space awarded to a subfield or a set of authors. Design/methodology/approach The theoretical methodology introduces the notion of credit spaces for a discipline. These quantify the total citation or publication credit accumulated by the scientists in the discipline. One can then examine how the credit is divided among the subfields. The design of the physics study uses the American Physical Society print journals to assign subdiscipline classifications to articles and gather citation, publication, and author information. Credit spaces for the collection of Physical Review Journal articles are computed as a proxy for physics. Findings There is a substantial difference in the value or impact of a specific subfield depending on the credit system employed to credit individual authors. Research limitations Subfield classification information is difficult to obtain. In the illustrative physics study, subfields are treated in groups designated by the Physical Review journals. While this collection of articles represents a broad part of the physics literature, it is not all the literature nor a random sample. Practical implications The method of crediting individual scientists has consequences beyond the individual and affects the perceived impact of whole subfields and institutions. Originality/value The article reveals the consequences of bibliometric methodology on subfields of a disciple by introducing a systematic theoretical framework for measuring the consequences
Erratum: Dark photons from the center of the Earth: Smoking-gun signals of dark matter [Phys. Rev. D <b>93</b> , 015014 (2016)]
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