Toward an understanding of short distance repulsions among baryons in QCD -- NBS wave functions and operator product expansion --

We report on our recent attempts to determine the short distance behaviors of general 2-baryon and 3-baryon forces, which are defined from the Nambu-Bethe-Salpeter(NBS) wave function, by using the operator product expansion and a renormalization group analysis in QCD. We have found that the repulsion at short distance increases as the number of valence quarks increases or when the number of different flavors involved decreases. This global tendency suggests a Pauli suppression principle among quark fields at work.Comment: 14 pages, add two exmples in sect.3.4, a version accepted for Progress of Theoretical Physic

An ideal toy model for confining, walking and conformal gauge theories: the O(3) sigma model with theta-term

A toy model is proposed for four dimensional non-abelian gauge theories coupled to a large number of fermionic degrees of freedom. As the number of flavors is varied the gauge theory may be confining, walking or conformal. The toy model mimicking this feature is the two dimensional O(3) sigma model with a theta-term. For all theta the model is asymptotically free. For small theta the model is confining in the infra red, for theta = pi the model has a non-trivial infra red fixed point and consequently for theta slightly below pi the coupling walks. The first step in investigating the notoriously difficult systematic effects of the gauge theory in the toy model is to establish non-perturbatively that the theta parameter is actually a relevant coupling. This is done by showing that there exist quantities that are entirely given by the total topological charge and are well defined in the continuum limit and are non-zero, despite the fact that the topological susceptibility is divergent. More precisely it is established that the differences of connected correlation functions of the topological charge (the cumulants) are finite and non-zero and consequently there is only a single divergent parameter in Z(theta) but otherwise it is finite. This divergent constant can be removed by an appropriate counter term rendering the theory completely finite even at theta > 0.Comment: 9 pages, 2 figures, minor modification, references adde

Resource requirements and speed versus geometry of unconditionally secure physical key exchanges

The imperative need for unconditional secure key exchange is expounded by the increasing connectivity of networks and by the increasing number and level of sophistication of cyberattacks. Two concepts that are information theoretically secure are quantum key distribution (QKD) and Kirchoff-law-Johnson-noise (KLJN). However, these concepts require a dedicated connection between hosts in peer-to-peer (P2P) networks which can be impractical and or cost prohibitive. A practical and cost effective method is to have each host share their respective cable(s) with other hosts such that two remote hosts can realize a secure key exchange without the need of an additional cable or key exchanger. In this article we analyze the cost complexities of cable, key exchangers, and time required in the star network. We mentioned the reliability of the star network and compare it with other network geometries. We also conceived a protocol and equation for the number of secure bit exchange periods needed in a star network. We then outline other network geometries and trade-off possibilities that seem interesting to explore.Comment: 13 pages, 7 figures, MDPI Entrop

Short Distance Repulsion Among Baryons

We review recent investigations on the short distance behaviors of potentials among baryons, which are formulated through the Nambu-Bethe-Salpeter (NBS) wave function. After explaining the method to define the potentials, we analyze the short distance behavior of the NBS wave functions and the corresponding potentials by combining the operator product expansion and a renormalization group analysis in the perturbation theory of QCD. These analytic results are compared with numerical results obtained in lattice QCD simulations.Comment: 16 pages, late

Graph-Embedding Empowered Entity Retrieval

In this research, we improve upon the current state of the art in entity retrieval by re-ranking the result list using graph embeddings. The paper shows that graph embeddings are useful for entity-oriented search tasks. We demonstrate empirically that encoding information from the knowledge graph into (graph) embeddings contributes to a higher increase in effectiveness of entity retrieval results than using plain word embeddings. We analyze the impact of the accuracy of the entity linker on the overall retrieval effectiveness. Our analysis further deploys the cluster hypothesis to explain the observed advantages of graph embeddings over the more widely used word embeddings, for user tasks involving ranking entities

Electron-phonon coupling in potassium-doped graphene: Angle-resolved photoemission spectroscopy

The electron-phonon coupling in potassium-doped graphene on Ir(111) is studied via the renormalization of the pi* band near the Fermi level, using angle-resolved photoemission spectroscopy. The renormalization is found to be fairly weak and almost isotropic, with a mass enhancement parameter of lambda= 0.28(6) for both the K-M and the K-G direction. These results are found to agree well with recent first principles calculations.Comment: 5 pages, 3 figure

The Highly Dynamic Behavior of the Innermost Dust and Gas in the Transition Disk Variable LRLL 31

We describe extensive synoptic multi-wavelength observations of the transition disk LRLL 31 in the young cluster IC 348. We combined four epochs of IRS spectra, nine epochs of MIPS photometry, seven epochs of cold-mission IRAC photometry and 36 epochs of warm mission IRAC photometry along with multi-epoch near-infrared spectra, optical spectra and polarimetry to explore the nature of the rapid variability of this object. We find that the inner disk, as traced by the 2-5micron excess stays at the dust sublimation radius while the strength of the excess changes by a factor of 8 on weekly timescales, and the 3.6 and 4.5micron photometry shows a drop of 0.35 magnitudes in one week followed by a slow 0.5 magnitude increase over the next three weeks. The accretion rate, as measured by PaBeta and BrGamma emission lines, varies by a factor of five with evidence for a correlation between the accretion rate and the infrared excess. While the gas and dust in the inner disk are fluctuating the central star stays relatively static. Our observations allow us to put constraints on the physical mechanism responsible for the variability. The variabile accretion, and wind, are unlikely to be causes of the variability, but both are effects of the same physical process that disturbs the disk. The lack of periodicity in our infrared monitoring indicates that it is unlikely that there is a companion within ~0.4 AU that is perturbing the disk. The most likely explanation is either a companion beyond ~0.4 AU or a dynamic interface between the stellar magnetic field and the disk leading to a variable scale height and/or warping of the inner disk.Comment: Accepted to ApJ. 10 pages of text, plus 11 tables and 13 figures at the en

Operator product expansion and the short distance behavior of 3-flavor baryon potentials

The short distance behavior of baryon-baryon potentials defined through Nambu-Bethe-Salpeter wave functions is investigated using the operator product expansion. In a previous analysis of the nucleon-nucleon case, corresponding to the SU(3) channels $27_s$ and $\overline{10}_a$, we argued that the potentials have a repulsive core. A new feature occurs for the case of baryons made up of three flavors: manifestly asymptotically attractive potentials appear in the singlet and octet channels. Attraction in the singlet channel was first indicated by quark model considerations, and recently been found in numerical lattice simulations. The latter have however not yet revealed asymptotic attraction in the octet channels; we give a speculative explanation for this apparent discrepancy.Comment: 11 pages, 2 figure