Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation

We study the decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation. Our approach for unquenching the theory is based on the heavy baryon perturbation theory in which the axial couplings for baryon - meson and the meson-meson-photon couplings from the chiral perturbation theory are used together with the QM moment couplings. It also involves the introduction of a form factor characterizing the structure of baryons considered as composite particles. Using the parameters obtained from fitting the octet baryon magnetic moments, we predict the decuplet baryon magnetic moments. The $\Omega^-$ magnetic moment is found to be in good agreement with experiment: $\mu_{\Omega^-}$ is predicted to be $-1.97 \mu_N$ compared to the experimental result of ($-$2.02 $\pm$ 0.05) $\mu_N$.Comment: 19 pages, 2 figure

Ferromagnetism below 10 K in Mn doped BiTe

Ferromagnetism is observed below 10 K in [Bi0.75Te0.125Mn0.125]Te. This material has the BiTe structure, which is made from the stacking of two Te-Bi-Te-Bi-Te blocks and one Bi-Bi block per unit cell. Crystal structure analysis shows that Mn is localized in the Bi2 blocks, and is accompanied by an equal amount of TeBi anti-site occupancy in the Bi2Te3 blocks. These TeBi anti-site defects greatly enhance the Mn solubility. This is demonstrated by comparison of the [Bi1-xMnx]Te and [Bi1-2xTexMnx]Te series; in the former, the solubility is limited to x = 0.067, while the latter has xmax = 0.125. The magnetism in [Bi1-xMnx]Te changes little with x, while that for [Bi1-2xTexMnx]Te shows a clear variation, leading to ferromagnetism for x > 0.067. Magnetic hysteresis and the anomalous Hall Effect are observed for the ferromagnetic samples.Comment: Accepted for publication in Phys. Rev.

Effective field theory and the quark model

We analyze the connections between the quark model (QM) and the description of hadrons in the low-momentum limit of heavy-baryon effective field theory in QCD. By using a three-flavor-index representation for the effective baryon fields, we show that the ``nonrelativistic'' constituent QM for baryon masses and moments is completely equivalent through O(m_s) to a parametrization of the relativistic field theory in a general spin--flavor basis. The flavor and spin variables can be identified with those of effective valence quarks. Conversely, the spin-flavor description clarifies the structure and dynamical interpretation of the chiral expansion in effective field theory, and provides a direct connection between the field theory and the semirelativistic models for hadrons used in successful dynamical calculations. This allows dynamical information to be incorporated directly into the chiral expansion. We find, for example, that the striking success of the additive QM for baryon magnetic moments is a consequence of the relative smallness of the non-additive spin-dependent corrections.Comment: 25 pages, revtex, no figure

Exploring temporal relationships among worrying, anxiety, and somatic symptoms

OBJECTIVES: The role of anxiety symptoms in the development of functional somatic symptoms (FSS) is unknown. Somatic symptoms may be triggered by or give rise to anxiety symptoms. This study aimed to 1) explore interrelationships among within-day worrying, feeling anxious, and somatic symptoms, and 2) investigate the association between these interrelationships and overall level of FSS. METHODS: This study included 767 participants (83% females, mean age 39 years), who were recruited through an online crowdsourcing study in the Dutch general population. Somatic, and anxiety symptoms were reported thrice daily (6-h intervals) for 30 days using electronic diaries. FSS were assessed at baseline (PHQ-15). Temporal relationships among worrying, feeling anxious, and somatic symptoms were modeled using a multilevel vector autoregressive model. RESULTS: We observed large heterogeneity in the within-person interrelationships among worrying, feeling anxious and somatic symptoms. Averaged over participants, higher-than-usual somatic symptoms were associated with increases in levels of worrying six hours later (B = 0.017, 95% CI [0.006, 0.027]). At the between-person level, FSS levels predicted the persistence of feeling anxious (B = 0.230 95% CI [0.105, 0.350]) and the carry-over of worrying to feeling anxious over six-hours (B = 0.159, 95% CI [0.031, 0.283]). CONCLUSIONS: In contrast to what we expected, higher levels of somatic symptoms over multiple weeks were associated with the persistence and carry-over of within-day anxiety-related symptoms. One within-person association between psychological and somatic symptoms during the day was observed, suggesting that, over a time span of 6-h, anxiety symptoms relate to somatic symptoms only in a minority of people from the general population

Physically meaningful and not so meaningful symmetries in Chern-Simons theory

We explicitly show that the Landau gauge supersymmetry of Chern-Simons theory does not have any physical significance. In fact, the difference between an effective action both BRS invariant and Landau supersymmetric and an effective action only BRS invariant is a finite field redefinition. Having established this, we use a BRS invariant regulator that defines CS theory as the large mass limit of topologically massive Yang-Mills theory to discuss the shift k \to k+\cv of the bare Chern-Simons parameter $k$ in conncection with the Landau supersymmetry. Finally, to convince ourselves that the shift above is not an accident of our regularization method, we comment on the fact that all BRS invariant regulators used as yet yield the same value for the shift.Comment: phyzzx, 21 pages, 2 figures in one PS fil

Effect of B-site Dopants on Magnetic and Transport Properties of LaSrCoRuO6_6

Effect of Co, Ru and Cu substitution at B and B' sites on the magnetic and transport properties of LaSrCoRuO$_6$ have been investigated. All the doped compositions crystallize in the monoclinic structure in the space group $P2_1/n$ indicating a double perovskite structure. While the magnetization and conductivity increase in Co and Ru doped compounds, antiferromagnetism is seen to strengthen in the Cu doped samples. These results are explained on the basis of a competition between linear Co-O-Ru-O-Co and perpendicular Co-O-O-Co antiferromagnetic interactions and due to formation of Ru-O-Ru ferromagnetic networks

The Lie Algebraic Significance of Symmetric Informationally Complete Measurements

Examples of symmetric informationally complete positive operator valued measures (SIC-POVMs) have been constructed in every dimension less than or equal to 67. However, it remains an open question whether they exist in all finite dimensions. A SIC-POVM is usually thought of as a highly symmetric structure in quantum state space. However, its elements can equally well be regarded as a basis for the Lie algebra gl(d,C). In this paper we examine the resulting structure constants, which are calculated from the traces of the triple products of the SIC-POVM elements and which, it turns out, characterize the SIC-POVM up to unitary equivalence. We show that the structure constants have numerous remarkable properties. In particular we show that the existence of a SIC-POVM in dimension d is equivalent to the existence of a certain structure in the adjoint representation of gl(d,C). We hope that transforming the problem in this way, from a question about quantum state space to a question about Lie algebras, may help to make the existence problem tractable.Comment: 56 page

CP Violation in Hyperon Nonleptonic Decays within the Standard Model

We calculate the CP-violating asymmetries A(Lambda_-^0) and A(Xi_-^-) in nonleptonic hyperon decay within the Standard Model using the framework of heavy-baryon chiral perturbation theory (chiPT). We identify those terms that correspond to previous calculations and discover several errors in the existing literature. We present a new result for the lowest-order (in chiPT) contribution of the penguin operator to these asymmetries, as well as an estimate for the uncertainty of our result that is based on the calculation of the leading nonanalytic corrections.Comment: 21 pages, 2 figures; discussion clarified, results & conclusions unchanged, to appear in Phys. Rev.

Translanguaging in mainstream education:a sociocultural approach

Due to the monolingual self-understanding of European nation-states, migration-induced multilingualism and the language mixing practices it triggers are not usually acknowledged as resources for learning within mainstream classrooms. The term translanguaging has recently been put forward as both a way of describing the flexible ways in which bilinguals draw upon their multiple languages to enhance their communicative potential and a pedagogical approach in which teachers and pupils use these practices for learning. However, little research has been conducted in how the translanguaging approach can be used in mainstream education to enhance knowledge. This study draws on videographic data recorded in 59 10th grade (15-year-olds) subject-matter classes in 4 secondary schools. Applying sociocultural discourse analysis to peer–peer interaction and therefore considering how learners scaffold one another as they participate in collaborative talk and in the co-construction of knowledge, results describe several functions of translanguaging for ‘exploratory talk’ leading to content-matter learning. Multilingual adolescents in naturalistic settings thus use their multilingualism to cognitively engage with content-based tasks and produce high-order speech acts embedded in complex talk