High-precision determination of the pion-nucleon σ\sigma-term from Roy-Steiner equations

We present a determination of the pion-nucleon ($\pi N$) $\sigma$-term $\sigma_{\pi N}$ based on the Cheng-Dashen low-energy theorem (LET), taking advantage of the recent high-precision data from pionic atoms to pin down the $\pi N$ scattering lengths as well as of constraints from analyticity, unitarity, and crossing symmetry in the form of Roy-Steiner equations to perform the extrapolation to the Cheng-Dashen point in a reliable manner. With isospin-violating corrections included both in the scattering lengths and the LET, we obtain $\sigma_{\pi N}=(59.1\pm 1.9\pm 3.0)$ MeV $=(59.1\pm 3.5)$ MeV, where the first error refers to uncertainties in the $\pi N$ amplitude and the second to the LET. Consequences for the scalar nucleon couplings relevant for the direct detection of dark matter are discussed.Comment: 6 pages, 1 figure; title changed by journal, version to be published in PR

Alexander and writhe polynomials for virtual knots

We give a new interpretation of the Alexander polynomial $\Delta_0$ for virtual knots due to Sawollek and Silver and Williams, and use it to show that, for any virtual knot, $\Delta_0$ determines the writhe polynomial of Cheng and Gao (equivalently, Kauffman's affine index polynomial). We also use it to define a second-order writhe polynomial, and give some applications.Comment: 22 pages, 19 figure

Is Yogācāra Phenomenology? Some Evidence from the Cheng weishi lun

There have been several attempts of late to read Yogācāra through the lens of Western phenomenology. I approach the issue through a reading of the Cheng weishi lun (Treatise on the Perfection of Consciousness Only), a seventh-century Chinese compilation that preserves the voices of multiple Indian commentators on Vasubandhu’s Triṃśikāvijñaptikārikā (Thirty Verses on Consciousness). Specifically, I focus on the “five omnipresent mental factors” (pañcasarvatraga, Chin. wu bianxing xinsuo) and the “four aspects” (Chin. sifen) of cognition. These two topics seem ripe, at least on the surface, for phenomenological analysis, particularly as the latter topic includes a discussion of “self-awareness” (svasaṃvedana, svasaṃvitti, Chin. zizheng). Yet we find that the Cheng weishi lun account has little in common with the tradition associated with Husserl and his heirs. The categories and modes of analysis in the Cheng weishi lun do not emerge from or aver to a systematic reflection on the nature of “lived experience” so much as they are focused on subliminal processes and metaphysical entities that belong to the domain of the noumenal. In my conclusion I suggest that the later pramāṇa tradition associated with Dignāga and Dharmakīrti—a tradition that profoundly influenced later Yogācāra exegesis in Tibet—did indeed take a “phenomenological turn.” But my comparison shows that both traditions falter when it comes to relating conceptual content to non-conceptual experience, and thus there is reason to be skeptical about claims that phenomenology is epistemologically grounded in how the world presents itself first-personally

Preface Modeling soil system: Complexity under your feet

none4openDe Bartolo S.; Otten W.; Cheng Q.; Tarquis A.M.De Bartolo, S.; Otten, W.; Cheng, Q.; Tarquis, A. M