Effects of initial axion production and photon--axion oscillation on type Ia supernova dimming

Recently, Csaki, Kaloper and Terning (CKT) suggested that axion-photon oscillation in the intergalactic medium can explain the observed dimming of distant type Ia supernovae. This mechanism works only if the initial axion flux is much smaller than the initial photon flux. We study several mechanisms for such initial axion production. The direct axion production in the supernovae, the photon-axion oscillation in the magnetic field of supernovae and in the magnetic field of their host galaxies are addressed. We find it likely that the initial axion flux is very small and therefore does not pose a problem to the CKT mechanism.Comment: 11 pages, Revtex4. Minor modifications in the tex

Sneutrino Mixing Phenomena

In any model with nonzero Majorana neutrino masses, the sneutrino and antisneutrino of the supersymmetric extended theory mix. We outline the conditions under which sneutrino-antisneutrino mixing is experimentally observable. The mass-splitting of the sneutrino mass eigenstates and sneutrino oscillation phenomena are considered.Comment: 12 pages, revtex + axodraw, 1 figure included. Minor change

Lepton Mass Matrix Models

The smallness and hierarchy in fermion parameters could be the result of selection rules due to an Abelian horizontal symmetry broken by a small parameter. When applied to the lepton sector, then for a large class of models, a number of interesting order of magnitude relations arise: with $i<j$, $m(\nu_i)/m(\nu_j)\sim\sin^2\theta_{ij}$; m(\ell^-_i)/m(\ell^-_j)\lsim\sin\theta_{ij}; m(\nu_i)/m(\nu_j)\gsim m^2(\ell^-_i)/m^2(\ell^-_j); m(\nu_e)\lsim m(\nu_\mu)\lsim m(\nu_\tau). The relations between neutrino masses and mixings may become exact if the horizontal symmetry together with holomorphy induce certain zero entries in the lepton mass matrices. A full high energy theory is likely to include scalars with flavor changing couplings and heavy leptons in vector representations; however, the masses of these particles are too heavy to be directly observed in experiment. Indirect evidence for the horizontal symmetry may arise from other sectors of the theory: non-degenerate sleptons are allowed as the symmetry aligns lepton and slepton mass matrices; light leptoquarks are allowed as the symmetry can make their couplings diagonal and chiral.Comment: 25 pages, uses harvmac; no figure

Big data, small concepts:Histosophy as an approach to longue-durée history

In this essay, we sketch out a method, histosophy, which makes possible the study of intellectual history and conceptual genealogy both in depth and over long periods of time. Histosophy uses digital tools to survey ‘large issues within small compasses.’ A genealogy of signifiers, it considers metonymic parts of a problem in order to contribute precisely and coherently to a larger perspective. We outline the theoretical contours of our approach. We exemplify how it works in practice by looking at the signifier ‘esprit de corps’, the study of which is presented in detail in the histosophical book The Genealogy of Esprit de Corps(Edinburgh University Press, 2019). The phrase ‘esprit de corps’ has been widely used since the eighteenth century in different discourses (political, military, sociological, etc.), but it is sufficiently limited that its genealogy can be traced across centuries and nations with precision, coherence, clarity, and with the help of automated search engines. By contrast, related but bigger concepts like freedom, individualism or solidarity are part of dozens of disparate and fuzzy discourses, so often uttered that the analysis of modern uses is problematic. The histosophical methodology is applicable in six discrete stages, here outlined

Managing AI Risks in an Era of Rapid Progress

In this short consensus paper, we outline risks from upcoming, advanced AI systems. We examine large-scale social harms and malicious uses, as well as an irreversible loss of human control over autonomous AI systems. In light of rapid and continuing AI progress, we propose urgent priorities for AI R&D and governance

Neutrino Masses and Mixing in Supersymmetric Models without RR Parity

We study neutrino masses and mixing in Supersymmetric Models without $R$ parity and with generic soft Supersymmetry breaking terms. Neutrinos acquire mass from various sources: tree level neutrino--neutralino mixing, loop effects and non--renormalizable operators. Abelian horizontal symmetries (invoked to explain the smallness and hierarchy in quark parameters) replace $R$ parity in suppressing neutrino masses. We find lower bounds on the mixing angles: \sin\theta_{ij} \gsim m(\ell_i^-)/m(\ell_j^-) ($i<j$) and unusual order of magnitude predictions for neutrino mass ratios: $m(\nu_e)/m(\nu_\mu)\sim\sin^2\theta_{12}$; $m(\nu_i)/m(\nu_\tau)\sim 10^{-7} \sin^2\theta_{i3}$ ($i=1,2$). Bounds from laboratory experiments exclude m_{\nu_\tau} \gsim 3\ MeV and the cosmological constraint that excludes m_{\nu_\tau} \gsim 100\ eV is not evaded. Neither the solar nor the atmospheric neutrino problems are likely to be solved by $\nu_\mu-\nu_e$ oscillations. These conclusions can be evaded if holomorphy plays an important role in the lepton Yukawa couplings.Comment: 16 pages, harvmac, no figures; Version to appear in Phys. Lett.

Historicism and constructionism: rival ideas of historical change

Simon ZB. Historicism and constructionism: rival ideas of historical change. History of European Ideas. 2019;45(8):1171-1190.A seemingly unitary appeal to history might evoke today two incompatible operations of historicization that yield contradictory results. This article attempts to understand two co-existing senses of historicity as conflicting ideas of historical change and rival practices of temporal comparison: historicism and constructionism. At their respective births, both claimed to make sense of the world and ourselves as changing over time. Historicism, dominating nineteenth-century Western thought and overseeing the professionalization of historical studies, advocated an understanding of the present condition of the human world as developing out of past conditions. Constructionism, dominating the second half of the twentieth century, understood the present condition as the recent invention of certain ‘historical’ environments, without prior existence. As competing ideas of historical change, they both entail a comparison between past and present conditions of their investigated subjects, but their practices of temporal comparison are irreconcilable and represent two distinct ways of historicization

21 Pelajaran untuk abad ke - 21

Dalam Sapiens, dia menjelajahi masa lalu kita. Dalam Homo Deus, dia menerawang masa depan kita. Kini, Yuval Noah Harari, salah seorang pemikir paling inovatif di planet ini, beralih ke masa kini untuk mendalami perkara-perkara yang paling mendesak hari ini. Bagaimana komputer dan robot mengubah makna menjadi manusia? Bagaimana kita menghadapi wabah berita palsu? Apakah negara, bangsa, dan agama masih relevan? Apa yang harus kita ajarkan kepada anak-anak kita? 21 Pelajaran untuk Abad Ke-21 karya Yuval Noah Harari adalah penyelidikan yang cermat dan visioner atas perkara-perkara yang paling mendesak selagi kita bergerak ke masa depan yang belum tertebak. Selagi teknologi melaju lebih cepat daripada pemahaman kita terhadapnya, selagi peretasan menjadi taktik perang, dan selagi dunia terasa makin terpolarisasi, Harari membahas tantangan menjalani hidup di tengah perubahan yang terus-menerus dan membingungkan, serta mengangkat pertanyaan-pertanyaan utama yang perlu kita ajukan kepada diri sendiri sehingga kita mampu terus bertahan. Dalam dua puluh satu bab yang provokatif sekaligus mendalam, Harari mengembangkan gagasan-gagasan yang dijelajahinya di buku-bukunya terdahulu, mengurai isu-isu politik, teknologi, sosial, dan eksistensial sambil memberi saran bagaimana menghadapi masa depan yang mungkin sama sekali berbeda: Bagaimana cara kita mempertahankan kebebasan memilih ketika Mahadata mengawasi kita? Akan seperti apa angkatan kerja masa depan, dan bagaimana seharusnya kita mempersiapkan diri? Bagaimana sebaiknya kita mengatasi ancaman terorisme? Mengapa demokrasi liberal mengalami krisis? Keahlian Harari memahami dari mana kita berasal dan ke mana kita menuju telah meraih imajinasi jutaan pembaca di seluruh dunia. Di buku ini, dia mengajak kita mempertimbangkan kembali nilai-nilai, makna, dan keterlibatan pribadi di dunia yang penuh keriuhan dan ketidakpastian. Saat kita kebanjiran informasi yang tak relevan, kejernihan menjadi kekuatan. Tantangan-tantangan zaman yang kompleks tersaji dengan jernih dan mudah dimengerti dalam 21 Pelajaran untuk Abad Ke-21.xvi, 357 hl