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A Tracker Solution for a Holographic Dark Energy Model

Hui Li,b; Zong-Kuan Guo; Yuan-Zhong ZhangSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We investigate a kind of holographic dark energy model with the future event horizon the IR cutoff and the equation of state ?1. In this model, the constraint on the equation of state automatically specifies an interaction between matter and dark energy. With this interaction included, an accelerating expansion is obtained as well as the transition from deceleration to acceleration. It is found that there exists a stable tracker solution for the numerical parameter d > 1, and d smaller than one will not lead to a physical solution. This model provides another possible phenomenological framework to alleviate the cosmological coincidence problem in the context of holographic dark energy. Some properties of the evolution which are relevant to cosmological parameters are also discussed. |

Note on the Slope Parameter of the Baryonic#3;b → #3;c Isgur-Wise Function

Ming-Qiu Huang; Hong-Ying Jin; J. G. K¨orner; Chun LiuSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Using the framework of the Heavy Quark Effective Theory we have re-analyzed the Isgur-Wise function describing semileptonic #3;b → #3;c decays in the QCD sum rule approach.The slope parameter of the Isgur-Wise function is found to be ρ2 = 1.35 ± 0.12, which isconsistent with an experimental measurement and a lattice calculation. To O(1/mb, 1/mc)of the heavy quark expansion the integrated #3;b decay width is used to extract the CKM matrix element Vcb for which we obtain a value of |Vcb| = 0.041±0.004 in excellent agreementwith the value of |Vcb| determined from semileptonic B → D? decays. |

Light-Cone HQET Sum Rules for the B → π Transition with 1/mQ Corrections

J. G. K¨orner; Chun Liu; Chi-Tau YanSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The B → π?ν weak decay form factors are calculated via light-cone sum rules within the framework of the heavy quark effective theory. We calculate the leading and the relevant sub-leading universal form factors. Our results are matched to the known soft pion limit. We also address the large pion energy limit of our sum rule results. Our results are compared with that of other approaches. |

NON-UNIVERSAL GAUGINO MASSES IN SUPERSYMMETRIC SO(10)

Nidal Chamoun; Chao-Shang Huang; Chun Liu; Xiao-Hong WuSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We consider SUSY SO(10) models in which SUSY breaking occurs via an F-term which does not transform as an SO(10) singlet. This results in non-universal GUT-scale gaugino masses leading to a different pattern of sparticle masses from what is expected in the minimal supergravity model (mSUGRA).We study three breaking chains of SO(10) down to the standard model through SU(4)×SU(2)×SU(2), SU(2)×SO(7) and ‘flipped’ SU(5) achieved by the representations 54 and 210 which appear in the symmetric product of two SO(10) adjoints. We examine the phenomenological implications of the different boundary conditions corresponding to the different breaking chainsand present the sparticle spectrum. |

A Phenomenological Study on Lepton Mass Matrix Textures

Chun Liu; Jeonghyeon SongSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The three active light neutrinos are used to explain the neutrino oscillations.The inherently bi-large mixing neutrino mass matrix and the Fritzsch type,bi-small mixing charged lepton mass matrix are assumed. By requiring the maximal #23;μ ?#23;#28; mixing for the atmospheric neutrino problem and the mass-squared difference approperiate for the almost maximal mixing solution to the solar neutrino problem, the following quantities are predicted: the #23;e?#23;μ mixing, Ve3, CP violation in neutrino oscillations, and the effective electron-neutrino mass relevant to neutrinoless double beta decays. |

Confronting Heavy Tau Neutrinos with Neutrino Oscillations

Chun LiuSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

If the tau neutrino is as heavy as 10 MeV which may have certain astrophysical implications, the neutrino mass pattern is studied so as to accommodate the new oscillation observations. It predicts that the electron neutrino has Marjorana mass around 0.05 eV. A supersymmetric model is described to realize the above scenario. |

Stau LSP and comparison with H± phenomenology

A.G. Akeroyd; Chun Liu; Jeonghyeon SongSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

In supersymmetric models with explicit breaking of R-parity the lightest su-persymmetric particle (LSP) may be the lightest stau, ?#28;1. Such a scenario would provide a clear sign of R-parity violating SUSY, although its phe-nomenology may resemble that of a charged Higgs boson, H±. We discuss various ways of distinguishing a LSP ?#28;1 from H± at future colliders, and address the case of ?#28;1 mimicking the signal for H±. As an example we suggest that the recent L3 signal for H+H? → qq′qq′ and H+H? → qq′#28;#23;#28; could be more easily explained by a LSP ?#28;1. |

A Model for Neutrino Warm Dark Matter and Neutrino Oscillations

Chun Liu; Jeonghyeon SongSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The muon- and tau-neutrinos with the mass in the keV range, which are allowed in a low reheating temperature cosmology, can compose the warm dark matter of the universe. A model of four light neutrinos including the keV scale #23;μ and #23;#28; is studied, which combines the seesaw mechanism and the Abelian flavor symmetry. The atmospheric neutrino anomaly is due to the #23;μ ? oscillation. The solar neutrino problem is answered by the oscillation into the light sterile neutrino, where the SMA, LMA, and LOW-QVO solutions can be accommodated in our scenario. |

Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The mass spectrum of the L = 1 orbitally excited heavy baryons with light quarks in the spin-flavor symmetric representation is studied by the 1/Nc expansion method in the framework of the heavy quark effective theory. The mixing effect from the baryons in the mixed representation is considered.The general pattern of the spectrum is predicted which will be verified bythe experiments in the near future. The 1/mQ and SU(3) corrections are also considered. Mass relations for the baryons #3;(?) c1 , #6;(?)c1 , #4;(′)(?)c1 , and (?)c1 arederived. |

1/mQ Corrections to the Heavy-to-Light-Vector Transitions in the HQET

Chao-Shang Huang; Chun Liu; Chi-Tau YanSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Within the HQET, the heavy to light vector meson transitions are systematically analyzed to the order of 1/mQ. Besides the four universal functions at the leading order, there are twenty-two independent universal form factors at the order of 1/mQ. Both the semileptonic decay B → #26; which is relevant to the |Vub| extraction, and the penguin induced decay B → K? which is important to new physics discovering, depend on these form factors.Phenomenological implications are discussed. |

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