278 research outputs found

    Quark CP-Phase and Froggatt-Nielsen Mechanism

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    On the basis of the Froggatt-Nielsen mechanism, we study quark flavor mixings in the SU(6)×SU(2)RSU(6) \times SU(2)_R model. The characteristic structure of the CKM matrix is attributed to the hierarchical effective Yukawa couplings due to the Froggatt-Nielsen mechanism and also to the state-mixings beyond the MSSM. We elucidate the detailed form of the CKM matrix elements and find interesting relations between the \textit{CP} violating phase and three mixing angles. Taking the existing data of three mixing angles, we estimate the quark \textit{CP}-phase at δ=(75±3)\delta = (75 \pm 3)^{\circ}. This result is in accord with observations.Comment: 14 pages, no figure. To be published in Physics Letters B. Several sentences are added. arXiv admin note: text overlap with arXiv:1210.376

    The String Unufication of Gauge Cuoplings and Gauge Kinetic Mixings

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    In the superstring models we have not only the complete {\bf 27} multiplets of E6E_6 but also extra incomplete (27+27)({\bf 27}+{\overline {\bf 27}}) chiral supermultiplets being alive at low energies. Associated with these additional multiplets, when the gauge symmetry contains more than one U(1)U(1) gauge group, there may exist gauge kinetic mixings among these U(1)U(1) gauge groups. In such cases the effect of gauge kinetic mixings should be incorporated into the study of unification of gauge couplings. We study these interesting effects systematically in these models. The string threshold effect is also taken into account. It is found that in the four-generation models we do not have a advisable solution of string unification of gauge couplings consistent with experimental values at the electroweak scale. We also discuss the possible scenarios to solve this problem.Comment: 27 pages, LaTeX, DPNU-93-16, AUE-03-9

    The Aligned SU(5)×U(1)2SU(5) \times U(1)^2 Model

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    In Calabi-Yau string compactification, it is pointed out that there exists a new type of SU(5)×U(1)2SU(5) \times U(1)^2 model (the aligned SU(5)×U(1)2SU(5) \times U(1)^2 model) in which the SU(5)SU(5) differs from the standard SU(5)SU(5) and also from the flipped SU(5)SU(5). With the aid of the discrete symmetry suggested from Gepner model, we construct a simple and phenomenologically interesting three-generation model with the aligned SU(5)×U(1)2SU(5) \times U(1)^2 gauge symmetry. The triplet-doublet splitting problem can be solved. It is also found that there is a realistic solution for solar neutrino problem and for the μ\mu -problem. At low energies this model is in accord with the minimal supersymmetric standard model except for the existence of singlet fields with masses of O(1)O(1)TeV.Comment: LaTeX 24 page

    Students with dyslexia: research projects at Northumbria University

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    Northumbria University has about 700 registered disabled students, the majority of whom (around 58 per cent) are registered as having dyslexia and account for approximately two per cent of the total student population. Therefore dyslexic students represent the largest single group of disabled students and are those with whom most staff are likely to come into contact. The research authors were keen to ascertain whether there was a difference in academic performance between dyslexic and non-dyslexic students in respect of degree classification and assignment marks and to investigate whether dyslexic students generally felt supported in their academic studies. Research involved both qualitative and quantitative strands and the areas explored include pre expectations; general support throughout study; methods, flexibility and clarity of learning tasks, in particular assessment and levels of performance throughout and at the end of their study. This research is ongoing, however, findings have proved invaluable as a basis in the construction of good practice guidelines in dealing with the pedagogic needs of this diverse student grou

    Long-term oxygen therapy in Japan: history, present status, and current problems

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    Historically, the progress of long term-oxygen therapy (LTOT) in Japan has been characterized by collaboration among academicgroups, policy makers, and industrial companies. The public health insurance program has covered the cost of LTOT since 1985.Thomas Petty’s group in Denver enthusiastically carried out the public implementation of LTOT and conveyed the concept of pulmonaryrehabilitation for the processing with LTOT. Although the target diseases of LTOT in Japan tended to be chronic obstructivepulmonary disease or sequelae of primary lung tuberculosis, it was soon applied for cardiac diseases as well as other pulmonarydiseases. Together with increasing medical costs for geriatric patients, the political conversion from hospital based care ofa traditional style to home care system has been performed, with two background reasons: the improvement of quality of life ofpatients and the reduction of the medical expense. Presently, LTOT plays a pivotal role in the successful implementation of homerespiratory care for elderly patients. In addition, this promotes comprehensive pulmonary rehabilitation, a team approach, andclose liaisons between primary care and hospitals. Currently, the total number of patients using LTOT exceeds 150,000. In Japan,LTOT resulted in an advancement in the medical care as well as in administrative decision to introduce it as a nationwide systemafter analyzing the results of opinion polls of patients with respiratory failure. However, the recent great earthquake in East Japanrevealed that many unresolved problems remain for these patients, and these issues are of great concern.Historically, the progress of long term-oxygen therapy (LTOT) in Japan has been characterized by collaboration among academicgroups, policy makers, and industrial companies. The public health insurance program has covered the cost of LTOT since 1985.Thomas Petty’s group in Denver enthusiastically carried out the public implementation of LTOT and conveyed the concept of pulmonaryrehabilitation for the processing with LTOT. Although the target diseases of LTOT in Japan tended to be chronic obstructivepulmonary disease or sequelae of primary lung tuberculosis, it was soon applied for cardiac diseases as well as other pulmonarydiseases. Together with increasing medical costs for geriatric patients, the political conversion from hospital based care ofa traditional style to home care system has been performed, with two background reasons: the improvement of quality of life ofpatients and the reduction of the medical expense. Presently, LTOT plays a pivotal role in the successful implementation of homerespiratory care for elderly patients. In addition, this promotes comprehensive pulmonary rehabilitation, a team approach, andclose liaisons between primary care and hospitals. Currently, the total number of patients using LTOT exceeds 150,000. In Japan,LTOT resulted in an advancement in the medical care as well as in administrative decision to introduce it as a nationwide systemafter analyzing the results of opinion polls of patients with respiratory failure. However, the recent great earthquake in East Japanrevealed that many unresolved problems remain for these patients, and these issues are of great concern

    Semidirect product gauge group [SU(3)c×SU(2)L]U(1)Y[SU(3)_{\rm c} \times SU(2)_{\rm L}]\rtimes U(1)_{\rm Y} and quantization of hypercharge

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    In the Standard Model the hypercharges of quarks and leptons are not determined by the gauge group SU(3)c×SU(2)L×U(1)YSU(3)_{\rm c} \times SU(2)_{\rm L} \times U(1)_{\rm Y} alone. We show that, if we choose the semidirect product group [SU(3)c×SU(2)L]U(1)Y[SU(3)_{\rm c} \times SU(2)_{\rm L}] \rtimes U(1)_{\rm Y} as its gauge group, the hyperchages are settled to be n/6modZ  (n=0,1,3,4)n/6 \mod {\mathbb{Z}}\;(n = 0,1,3,4) . In addition, the conditions for gauge-anomaly cancellation give strong constraints. As a result, the ratios of the hypercharges are uniquely determined and the gravitational anomaly is automatically canceled. The standard charge assignment to quarks and leptons can be properly reproduced. For exotic matter fields their hypercharges are also discussed.Comment: 17 pages, 2 tables; LaTeX; typos corrected, references added or replaced, argument in Secs. 2 and 3 revised, results unchanged; to be published in Phys. Rew.

    The Weak-Scale Hierarchy and Discrete Symmetries

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    In the underlying Planck scale theory we introduce a certain type of discrete symmetry, which potentially brings the stability of the weak-scale hierarchy under control. Under the discrete symmetry the μ\mu -problem and the tadpole problem can be solved simultaneously without relying on some fine-tuning of parameters. Instead, it is required that doublet Higgs and color-triplet Higgs fields reside in different irreducible representations of the gauge symmetry group at the Planck scale and that they have distinct charges of the discrete symmetry group.Comment: 13 pages, LATEX, 1 figures(not included, available on request by fax or Postscript file
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