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200 papers

Gauge coupling unification is studied in the MSSM with non-universal soft supersymmetry breaking terms. If gaugino masses are sufficiently smaller than scalar soft masses and the scalar soft masses have also certain types of…

High Energy Physics - Phenomenology · Physics 2009-10-28 T. Kobayashi , D. Suematsu , Y. Yamagishi

A model independent analysis shows that the running of the spectral index of the three year WMAP results can be nicely realized in noncommutative inflation. We also re-examine some concrete noncommutative inflation models. We find that a…

Astrophysics · Physics 2009-11-11 Qing-Guo Huang , Miao Li

Composite system is studied in noncommutative phase space with preserved rotational symmetry. We find conditions on the parameters of noncommutativity on which commutation relations for coordinates and momenta of the center-of-mass of…

Quantum Physics · Physics 2018-02-27 Kh. P. Gnatenko , V. M. Tkachuk

We investigate the primordial power spectrum of the density perturbations based on the assumption that spacetime is noncommutative in the early stage of inflation. Due to the spacetime noncommutativity, the primordial power spectrum can…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-02 Khamphee Karwan

We study the cosmological implications of the space-space noncommutative inflation and present formulae for the spectral index and its running. Our results show that deviations from the spectral index and its running depend on the…

Astrophysics · Physics 2009-11-10 S. A. Alavi , Forough Nasseri

We propose a variation of spacetime noncommutative field theory to realize the stringy spacetime uncertainty relation without breaking any of the global symmetries of the homogeneous isotropic universe. We study the spectrum of metric…

High Energy Physics - Theory · Physics 2009-11-07 Robert Brandenberger , Pei-Ming Ho

We propose a mechanism borrowed from string theory which yields a non-singular transition from a phase of Ekpyrotic contraction to the expanding phase of Standard Big Bang cosmology. The same mechanism converts the initial vacuum spectrum…

High Energy Physics - Theory · Physics 2020-04-21 Robert Brandenberger , Ziwei Wang

We present simple analytic approximations for the linear and fully evolved nonlinear mass power spectrum for spatially flat cold dark matter (CDM) cosmological models with quintessence (Q). Quintessence is a time evolving, spatially…

Astrophysics · Physics 2009-10-31 Chung-Pei Ma , R. R. Caldwell , Paul Bode , Limin Wang

In the standard model production of on-shell Z boson at a photon collider (or Z decays into $\gamma\gamma$) is strictly forbidden by angular momentum conservation and Bose statistics (the Yang's Theorem). In the standard model with…

High Energy Physics - Phenomenology · Physics 2009-11-11 Xiao-Gang He , Xue-Qian Li

Koide's mass relation of charged leptons has been extended to quarks and neutrinos, and we prove here that this relation is independent of energy scale in a huge energy range from $1 {GeV}$ to $2\times10^{16} {GeV}$. By using the parameters…

High Energy Physics - Phenomenology · Physics 2009-11-11 Nan Li , Bo-Qiang Ma

We study the spectrum of loops as a part of a complete network of cosmic strings in flat spacetime. After a long transient regime, characterized by production of small loops at the scale of the initial conditions, it appears that a true…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Vitaly Vanchurin , Ken D. Olum , Alexander Vilenkin

We try to constrain the noncommutativity length scale of the theoretical model given in Ref. [1] using the observational data from ACBAR, CBI and five year WMAP. The noncommutativity parameter is not constrained by WMAP data, however ACBAR…

String/M theory inspires an uncertainty relation between space and time which deviates from general relativity. It is possible to explore this deviation from cosmological observations, in particular from the CMB fluctuation spectrum. This…

Astrophysics · Physics 2008-11-26 Qing-Guo Huang , Miao Li

In this paper I discuss connections between the noncommutative geometry approach to the standard model on one side, and the internal space coming from strings on the other. The standard model in noncommutative geometry is described via the…

High Energy Physics - Theory · Physics 2008-11-26 Fedele Lizzi

Non commutative geometry is creating new possibilities for physics. Quantum spacetime geometry and post inflationary models of the universe with matter creation have an enormous range of scales of time, distance and energy in between. There…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ajay Patwardhan

A particle spectrum below the string scale in accordance with predictions from heterotic string theory yields a Planck mass $m_{Pl}=(8\pi G_N)^{-1/2}$ which exceeds the string scale by a factor $\simeq 61.9$. A Planck mass…

High Energy Physics - Theory · Physics 2007-05-23 Rainer Dick

We present a new inflation model, known as noncommutative decrumpling inflation, in which space has noncommutative geometry with time variability of the number of spatial dimensions. Within the framework of noncommutative decrumpling…

High Energy Physics - Theory · Physics 2009-11-10 Forough Nasseri , S. A. Alavi

We consider a two-point spatial lattice approximation to an open string moving in a flat background with B field. It gives a constrained dipole system under the influence of a vector potential. Solving and quantizing this system recover all…

High Energy Physics - Theory · Physics 2009-10-31 Zheng Yin

We review the noncommutative spectral geometry, a gravitational model that combines noncommutative geometry with the spectral action principle, in an attempt to unify General Relativity and the Standard Model of electroweak and strong…

High Energy Physics - Theory · Physics 2014-03-25 Mairi Sakellariadou

Non-commutative geometry at inflation can give arise to parity violating modulations of the primordial power spectrum. We develop the statistical tools needed for investigating whether these modulations are evident in the Cosmic Microwave…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-25 N. E. Groeneboom , M. Axelsson , D. F. Mota , T. Koivisto