57,990 research outputs found

    Strangeness magnetic form factor of the proton in the extended chiral quark model

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    Background: Unravelling the role played by nonvalence flavors in baryons is crucial in deepening our comprehension of QCD. Strange quark, a component of the higher Fock states in baryons, is an appropriate tool to investigate nonperturbative mechanisms generated by the pure sea quark. Purpose: Study the magnitude and the sign of the strangeness magnetic moment μs\mu_s and the magnetic form factor (GMsG_M^s) of the proton. Methods: Within an extended chiral constituent quark model, we investigate contributions from all possible five-quark components to μs\mu_s and GMs(Q2)G_M^s (Q^2) in the four-vector momentum range Q21Q^2 \leq 1 (GeV/c)2^2. Probability of the strangeness component in the proton wave function is calculated employing the 3P0^3 P_0 model. Results: Predictions are obtained without any adjustable parameters. Observables μs\mu_s and GMs(Q2)G_M^s (Q^2) are found to be small and negative, consistent with the lattice-QCD findings as well as with the latest data released by the PVA4 and HAPPEX Collaborations. Conclusions: Due to sizeable cancelations among different configurations contributing to the strangeness magnetic moment of the proton, it is indispensable to (i) take into account all relevant five-quark components and include both diagonal and non-diagonal terms, (ii) handle with care the oscillator harmonic parameter ω5\omega_5 and the ssˉ{s \bar s} component probability.Comment: References added, typos corrected, accepted for publication by Phys. Rev.

    Person re-identification by robust canonical correlation analysis

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    Person re-identification is the task to match people in surveillance cameras at different time and location. Due to significant view and pose change across non-overlapping cameras, directly matching data from different views is a challenging issue to solve. In this letter, we propose a robust canonical correlation analysis (ROCCA) to match people from different views in a coherent subspace. Given a small training set as in most re-identification problems, direct application of canonical correlation analysis (CCA) may lead to poor performance due to the inaccuracy in estimating the data covariance matrices. The proposed ROCCA with shrinkage estimation and smoothing technique is simple to implement and can robustly estimate the data covariance matrices with limited training samples. Experimental results on two publicly available datasets show that the proposed ROCCA outperforms regularized CCA (RCCA), and achieves state-of-the-art matching results for person re-identification as compared to the most recent methods

    Reference face graph for face recognition

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    Face recognition has been studied extensively; however, real-world face recognition still remains a challenging task. The demand for unconstrained practical face recognition is rising with the explosion of online multimedia such as social networks, and video surveillance footage where face analysis is of significant importance. In this paper, we approach face recognition in the context of graph theory. We recognize an unknown face using an external reference face graph (RFG). An RFG is generated and recognition of a given face is achieved by comparing it to the faces in the constructed RFG. Centrality measures are utilized to identify distinctive faces in the reference face graph. The proposed RFG-based face recognition algorithm is robust to the changes in pose and it is also alignment free. The RFG recognition is used in conjunction with DCT locality sensitive hashing for efficient retrieval to ensure scalability. Experiments are conducted on several publicly available databases and the results show that the proposed approach outperforms the state-of-the-art methods without any preprocessing necessities such as face alignment. Due to the richness in the reference set construction, the proposed method can also handle illumination and expression variation

    Mission policies of the Episcopal Church in the Philippines (ECP), 1901-1980: their contribution to the regional character of the Church

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    This study demonstrates the extensive contribution of successive mission policies from 1901 to 1980 to the regional character of the Episcopal Church in the Philippines (ECP). The policy of concentration from 1901 to 1919, which focused church’s work in certain areas of Luzon and Mindanao, continued to impact the development of its mission in spite of the adoption of new policies in the succeeding years. This is because it was primarily developed in relation to the issue of marginality in Philippine society, a factor that remained vital to new policies although it was not always explicitly acknowledged. Although the policy of consolidation from 1920 to 1940 aimed at strengthening the initial mission work, it also allowed expansion for the sake of marginalized people like the Tiruray in Upi, Maguindanao. After World War II to 1962, the church adopted policies of centralization - gathering key institutions in one centre - and expansion of influence - bringing church’s influence to the mainstream of Philippine society. However, when the church pursued its expansion to the lowland Filipinos in partnership with the Iglesia Filipina Independiente (IFI), the concentration of its work amongst the marginalized people in the Cordillera and Mindanao was further enhanced. From 1962 to 1980, the church adopted parallel policies of devolution – Filipinization of leadership - and decentralization – division of the district into dioceses. However, since the policy of decentralization was developed not only for efficient administration of the church but also for its regional expansion, it further contributed to concentration of work in places where the church has been previously working. The framework of ‘mission history after the “world-Christian turn” ’ employed in this study made it possible to arrive at the above conclusions in spite of relying on sources that are predominantly colonial, because it demands reconceiving mission history in the light of World Christianity. In particular, this mission history articulates Filipino voices that have been muted and yet can be detected in the way missionaries dealt with issues like marginality. The capacity to highlight local context and local voices in this framework is partly due to the identification of the double role of mission policies - mediating and synthesizing - in the dialogical relationship between theory (theology, theories, ideals) and practice (expediencies or what is happening on the ground) in the work of Christian mission. This study contributes to the broadening of mission history as well as demonstrating the importance of mission history in the continuous growth and evolution of World Christianity as an area of study

    Intrinsic charm content of the nucleon and charmness-nucleon sigma term

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    In the extended chiral constituent quark model, the intrinsic ccˉc \bar{c} content of the nucleon is investigated. The probabilities of the quark-antiquark components in the nucleon wave functions are calculated by taking the nucleon to be admixtures of three- and five-quark components, with the relevant transitions handled {\it via} the 3^{3}P0_{0} mechanism. Predictions for the probability of the ccˉc \bar{c} in the nucleon wave function and the charmness-nucleon sigma term are presented. Our numerical results turn out to be consistent with the predictions from various other approaches reported in the literature.Comment: Accepted for publication in Phys. Rev.
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