Deconfinement of neutron star matter within the Nambu-Jona-Lasinio model

We study the deconfinement transition of hadronic matter into quark matter under neutron star conditions assuming color and flavor conservation during the transition. We use a two-phase description. For the hadronic phase we use different parameterizations of a non-linear Walecka model which includes the whole baryon octet. For the quark matter phase we use an SU(3)_f Nambu-Jona-Lasinio effective model including color superconductivity. Deconfinement is considered to be a first order phase transition that conserves color and flavor. It gives a short-lived transitory colorless-quark-phase that is not in beta-equilibrium, and decays to a stable configuration in tau ~ tau_{weak} ~ 10^{-8} s. However, in spite of being very short lived, the transition to this intermediate phase determines the onset of the transition inside neutron stars. We find the transition free-energy density for temperatures typical of neutron star interiors. We also find the critical mass above which compact stars should contain a quark core and below which they are safe with respect to a sudden transition to quark matter. Rather independently on the stiffness of the hadronic equation of state (EOS) we find that the critical mass of hadronic stars (without trapped neutrinos) is in the range of ~ 1.5 - 1.8 solar masses. This is in coincidence with previous results obtained within the MIT Bag model.Comment: 10 pages, 2 figure

Understanding and Encouraging Student Diversity: Involving the Community

The Committee on Diversity in the Collegeof Educationof ColumbusStateUniversityhas been involved in several programs since 2004 to increase the diversity in the college, both with students and faculty/staff. This has been accomplished by involving the community in and around Columbus, Georgia. This article addresses the committee’s work to adapt several strategies to develop a three-pronged approach: (1) acceptance of diversity within our ranks, (2) partnering with One Columbus, a community organization to promote diversity, racial harmony, and unity in Columbus, and (3) participation with CHISPA, a Hispanic organization intended to recruit and retain Hispanic students at CSU and to build community in the College of Education. Ideas for each of these are shared

Portuguese: Corpora, coordination and agreement

This paper reports some results from a corpus study of Portuguese, and explores their implications for the analysis of agreement processes involving coordinate structures (CSs), especially as regards gender agreement withi

Empirical evaluation of sequence-to-sequence models for word discovery in low-resource settings

Since Bahdanau et al. [1] first introduced attention for neural machine translation, most sequence-to-sequence models made use of attention mechanisms [2, 3, 4]. While they produce soft-alignment matrices that could be interpreted as alignment between target and source languages, we lack metrics to quantify their quality, being unclear which approach produces the best alignments. This paper presents an empirical evaluation of 3 of the main sequence-to-sequence models for word discovery from unsegmented phoneme sequences: CNN, RNN and Transformer-based. This task consists in aligning word sequences in a source language with phoneme sequences in a target language, inferring from it word segmentation on the target side [5]. Evaluating word segmentation quality can be seen as an extrinsic evaluation of the soft-alignment matrices produced during training. Our experiments in a low-resource scenario on Mboshi and English languages (both aligned to French) show that RNNs surprisingly outperform CNNs and Transformer for this task. Our results are confirmed by an intrinsic evaluation of alignment quality through the use Average Normalized Entropy (ANE). Lastly, we improve our best word discovery model by using an alignment entropy confidence measure that accumulates ANE over all the occurrences of a given alignment pair in the collection