TY - JOUR

T1 - Observational constraints on patch inflation in noncommutative spacetime

AU - Calcagni, Gianluca

AU - Tsujikawa, Shinji

PY - 2004/11

Y1 - 2004/11

N2 - We study constraints on a number of patch inflationary models in noncommutative spacetime using a compilation of recent high-precision observational data. In particular, the four-dimensional general relativistic (GR) case, the Randall-Sundrum (RS), and the Gauss-Bonnet brane world scenarios are investigated by extending previous commutative analyses to the infrared limit of a maximally symmetric realization of the stringy uncertainty principle. The effect of spacetime noncommutativity modifies the standard consistency relation between the tensor spectral index and the tensor-to-scalar ratio. We perform likelihood analyses in terms of inflationary observables using new consistency relations and confront them with large-field inflationary models with potential V ∝ φp in two classes of noncommutative scenarios. We find a number of interesting results: (i) the quartic potential (p = 4) is rescued from marginal rejection in the class 2 GR case, and (ii) steep inflation driven by an exponential potential (p → ∞) is allowed in the class 1 RS case. Spacetime noncommutativity can lead to blue-tilted scalar and tensor spectra even for monomial potentials, thus opening up a possibility to explain the loss of power observed in cosmic microwave background anisotropies. We also explore patch inflation with a Dirac-Born-Infeld tachyon field and explicitly show that the associated likelihood analysis is equivalent to the one in the ordinary scalar field case by using horizon-flow parameters. It turns out that tachyon inflation is compatible with observations in all patch cosmologies even for large p.

AB - We study constraints on a number of patch inflationary models in noncommutative spacetime using a compilation of recent high-precision observational data. In particular, the four-dimensional general relativistic (GR) case, the Randall-Sundrum (RS), and the Gauss-Bonnet brane world scenarios are investigated by extending previous commutative analyses to the infrared limit of a maximally symmetric realization of the stringy uncertainty principle. The effect of spacetime noncommutativity modifies the standard consistency relation between the tensor spectral index and the tensor-to-scalar ratio. We perform likelihood analyses in terms of inflationary observables using new consistency relations and confront them with large-field inflationary models with potential V ∝ φp in two classes of noncommutative scenarios. We find a number of interesting results: (i) the quartic potential (p = 4) is rescued from marginal rejection in the class 2 GR case, and (ii) steep inflation driven by an exponential potential (p → ∞) is allowed in the class 1 RS case. Spacetime noncommutativity can lead to blue-tilted scalar and tensor spectra even for monomial potentials, thus opening up a possibility to explain the loss of power observed in cosmic microwave background anisotropies. We also explore patch inflation with a Dirac-Born-Infeld tachyon field and explicitly show that the associated likelihood analysis is equivalent to the one in the ordinary scalar field case by using horizon-flow parameters. It turns out that tachyon inflation is compatible with observations in all patch cosmologies even for large p.

UR - http://www.scopus.com/inward/record.url?scp=42749099603&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=42749099603&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.70.103514

DO - 10.1103/PhysRevD.70.103514

M3 - Article

AN - SCOPUS:42749099603

SN - 0556-2821

VL - 70

SP - 103514-1-103514-16

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

IS - 10

M1 - 103514

ER -