5,011 research outputs found
Long life stau in the minimal supersymmetric standard model
We study the stau lifetime in a scenario with the LSP taken to be a
neutralino and the NLSP being a stau, based on the minimal supersymmetric
Standard Model. The mass difference between the LSP and NLSP, , must
satisfy a few % or less for coannihilation to
occur, where is the neutralino mass. We calculate the stau
lifetime from the decay modes ,
, and and
discuss its dependence on various parameters. We find that the lifetime is in
the range -- sec for GeV. We
also discuss the connection with lepton flavor violation if there is mixing
between sleptons.Comment: 15 pages, 5 figure
Constraints from Unrealistic Vacua in Supersymmetric Standard Model with Neutrino Mass Operators
We analyze a scalar potential of the minimal supersymmetric standard model
(MSSM) with neutrino mass operators along Unbounded-From-Below (UFB) and Color
and/or Charged Breaking (CCB) directions. We show necessary conditions to avoid
the potential minima which can be deeper than the realistic vacuum. These
conditions would constrain more strongly than conditions in the MSSM without
taking into account neutrino mass operators, and can improve the predictive
power of supersymmetric models with neutrino mass operators.Comment: 11 pages, 4 figure
On the Logarithmic Asymptotics of the Sixth Painleve' Equation (Summer 2007)
We study the solutions of the sixth Painlev\'e equation with a logarithmic
asymptotic behavior at a critical point. We compute the monodromy group
associated to the solutions by the method of monodromy preserving deformations
and we characterize the asymptotic behavior in terms of the monodromy itself.Comment: LaTeX with 8 figure
Non-ideal behavior of intramolecular structure factor of dilute polymers in a theta solvent
We study the configurational properties of single polymers in a theta solvent
by Monte Carlo simulation of the bond fluctuation model. The intramolecular
structure factor at the theta point is found to be distinctively different from
that of the ideal chain. The structure factor shows a hump around
and a dip around in the Kratky plot with being the radius
of gyration. This feature is apparently similar to that in a melt. The
theoretical expression by the simple perturbation expansion to the first order
in terms of the Mayer function can be fitted to the obtained structure factor
quite well, but the second virial coefficient cannot be set to zero.Comment: 8 pages, 7figure
Possible solution to the Li problem by the long lived stau
Modification of standard big-bang nucleosynthesis is considered in the
minimal supersymmetric standard model to resolve the excessive theoretical
prediction of the abundance of primordial lithium 7. We focus on the stau as a
next-lightest superparticle, which is long lived due to its small mass
difference with the lightest superparticle. It provides a number of additional
decay processes of and . A particularly
important process is the internal conversion in the stau-nucleus bound state,
which destroys the and effectively. We show
that the modification can lead to a prediction consistent with the observed
abundance of .Comment: 6 pages, 5 figure
Nanoscale anisotropic structural correlations in the paramagnetic and ferromagnetic phases of Nd0.5Sr0.5 MnO3
We report x-ray scattering studies of short-range structural correlations and
diffuse scattering in Nd0.5Sr0.5MnO3. On cooling, this material undergoes a
series of transitions, first from a paramagnetic insulating (PI) to a
ferromagnetic metallic (FM) phase, and then to a charge-ordered (CO) insulating
state. Highly anisotropic structural correlations were found in both the PI and
FM states. The correlations increase with decreasing temperature, reaching a
maximum at the CO transition temperature. Below this temperature, they abruptly
collapsed. Single-polaron diffuse scattering was also observed in both the PI
and FM states suggesting that substantial local lattice distortions are present
in these phases. We argue that our measurements indicate that nanoscale regions
exhibiting layered orbital order exist in the paramagnetic and ferromagnetic
phases of Nd0.5Sr0.5MnO3.Comment: 5 pages, 4 embedded figure
Kerangka kemahiran employability senibina graduan politeknik
Sehingga tahun 2014, hampir seratus peratus graduan diploma politeknik Malaysia diterima bekerja di pasaran pekerjaan Malaysia. Namun begitu, terdapat peningkatan tren pengangguran dalam kalangan graduan diploma senibina politeknik sejak tahun 2012. Salah satu punca kepada peningkatan jumlah pengangguran ini disebabkan oleh ketidak selarian antara kemahiran employability yang diperlukan oleh graduan senibina dan pihak firma binaan. Penekanan terhadap kemahiran employability yang bertepatan mengikut bidang penting dalam membantu graduan memahami dan mengaplikasikan kemahiran tersebut di alam pekerjaan. Kajian ini dijalankan bertujuan untuk menghasilkan kerangka kemahiran Employability Senibina (Ar–ES) bagi graduan diploma senibina politeknik yang memenuhi keperluan pihak firma binaan. Kajian ini turut bertujuan untuk mengenal pasti konstruk dan dimensi Ar–ES yang dominan diperlukan responden kajian. Kaedah gabungan penerokaan digunakan melibatkan sampel seramai 285 orang graduan diploma senibina politeknik dan 226 orang responden mewakili majikan firma binaan yang terdapat di Malaysia. Analisis data mendapati lima konstruk dan tujuh belas dimensi Ar–ES telah dikenal pasti. Konstruk etika profesional merupakan konstruk paling dominan diperlukan oleh graduan (logit= -0.19) dan pihak majikan (logit= -0.17). Hasil analisis Differential Group Functioning (DGF) mendapati tidak terdapat perbezaan yang signifikan antara graduan senibina dan pihak majikan bagi kesemua konstruk dan dimensi kerangka Ar–ES yang dominan diperlukan. Pengkaji turut mendapati bahawa kerangka Ar–ES yang diuji bersifat unidimensi dan disahkan secara empirikal dengan memenuhi kriteria analisis Principle Component Analysis (PCA). Di akhir kajian, pengkaji telah menghasilkan kerangka Ar–ES untuk graduan politeknik bagi memenuhi kehendak firma binaan Malaysia. Penghasilan kerangka ini diharap dapat membantu meningkatkan kebolehpasaran graduan diploma senibina di Malaysia dan menangani isu pengangguran dalam kalangan mereka
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