118436211
Bispectrum signatures of a modified vacuum in single field inflation with a small speed of sound
Deviations from the Bunch-Davies vacuum during an inflationary period can leave a testable imprint on the higher-order correlations of the CMB and large scale structures in the Universe. The effect is particularly pronounced if the statistical non-Gaussianity is inherently large, such as in models of inflation with a small speed of sound, e.g. DBI. First reviewing the motivations for a modified vacuum, we calculate the non-Gaussianity for a general action with a small speed of sound. The shape of its bispectrum is found to most resemble the `orthogonal' or `local' templates depending on the phase of the Bogolyubov parameter. In particular, for DBI models of inflation the bispectrum can have a profound `local' template feature, in contrast to previous results. Determining the projection into the observational templates allows us to derive constraints on the absolute value of the Bogolyubov parameter. In the small sound speed limit, the derived constraints are generally stronger than the constraint obtainable from the power spectrum. The bound on the absolute value of the Bogolyubov parameter ranges from the 10−6 to the 10−3 level for H/Λc = 10−3, depending on the specific details of the model, the sound speed and the phase of the Bogolyubov parameter.
119247401
Spin-statistics violations from heterotic string worldsheet instantons
In this paper, we consider the role that worldsheet instantons in the heterotic string could play in spin-statistics violations. Such violations are nonperturbative in the string tension and so would not appear in the spacetime effective action, producing a unique signature of string theory and the details of compactification. By performing a Bogomol'nyi transformation it is shown that there are no instanton solutions in the simplest model proposed by Harvey and Liu, but it is conjectured that more sophisticated models may yield solutions. If such instantons do exist, their effect might be measured by upcoming experiments.
13946666
A Quantum Mechanical Model of Spherical Supermembranes
We present a quantum mechanical model of spherical supermembranes. Using superfields to represent the cartesian coordinates of the membrane, we are able to exactly determine its supersymmetric vacua. We find there are two classical vacua, one corresponding to an extended membrane and one corresponding to a point-like membrane. For the = 2 case, instanton effects then lift these vacua to massive states. For the = 4 case, there is no instanton tunneling, and the vacua remain massless. Similarities to spherical supermembranes as giant gravitons and in Matrix theory on pp-waves is discussed.
84839474
Model-Independent Signatures of New Physics in Slow-Roll Inflation
We compute the universal generic corrections to the power spectrum in slow-roll inflation due to unknown high-energy physics. We arrive at this result via a careful integrating out of massive fields in the "in-in" formalism yielding a consistent and predictive low-energy effective description in time-dependent backgrounds. The density power spectrum is universally modified at leading order in $H/M$, the ratio of the scale of inflation to the scale of new physics; the tensor power spectrum receives only subleading corrections. In doing so, we show how to make sense of a physical momentum-cut-off in loop integrals despite dynamical redshifts, and how the result can be captured in a combined effective action/effective density matrix, where the latter contains non-adiabatic terms which modify the boundary conditions.
15602764
Two black hole holography, lensing, and intensity
We numerically verify the analysis of the 'expanding horizon' theory of Susskind in relation to the 't Hooft holographic conjecture. By using a numerical simulation to work out the holographic image formed by two black holes upon a screen very far away, it is seen that it is impossible for a horizon to hide behind another. We also compute the holographic intensity distribution of such an arrangement.
118874471
Model-Independent Signatures of New Physics in non-Gaussianity
Instituut-Lorentz for Theoretical Physics, University of Leiden, Leiden 2333CA, The Netherlands(Dated: February 6, 2012)We compute the model-independent contributions to the primordial bispectrum and trispectrum inde Sitter space due to high-energy physics. We do this by coupling a light inaton to an auxiliaryheavy eld, and then evaluating correlation functions in the Schwinger-Keldysh \in-in" formalism.The high-energy physics produces corrections parametrized by H=Mwhere His the scale of ina-tion and M is the mass of the heavy eld. The bispectrum peaks near the elongated shape, butotherwise contains no features. On the other hand, the trispectrum contains oscillations which areof a magnitude possibly detectable using upcoming data. These oscillations are the cosmologicalanalogue of energy eigenstate mixing.
16544780
XMM-Newton, Chandra, and CGPS observations of the Supernova Remnants G85.4+0.7 and G85.9–0.6
We present an XMM-Newton detection of two low radio surface brightness supernova remnants (SNRs), G85.4+0.7 and G85.9–0.6, discovered with the Canadian Galactic Plane Survey (CGPS). High-resolution XMM-Newton images revealing the morphology of the diffuse emission, as well as discrete point sources, are presented and correlated with radio and Chandra images. The new data also permit a spectroscopic analysis of the diffuse emission regions, and a spectroscopic and timing analysis of the point sources. Distances have been determined from H I and CO data to be 3.5 ± 1.0 kpc for SNR G85.4+0.7 and 4.8 ± 1.6 kpc for SNR G85.9–0.6. The SNR G85.4+0.7 is found to have a temperature of ~12-13 MK and a 0.5-2.5 keV luminosity of ~(1–4) × 1033D23.5 erg s−1 (where D3.5 is the distance in units of 3.5 kpc), with an electron density ne of ~(0.07–0.16) (fD3.5)−1/2 cm−3 (where f is the volume filling factor) and a shock age of ~(9–49) (fD3.5)1/2 kyr. The SNR G85.9–0.6 is found to have a temperature of ~15-19 MK and a 0.5-2.5 keV luminosity of ~(1–4) × 1034D24.8 erg s−1 (where D4.8 is the distance in units of 4.8 kpc), with an electron density ne of ~(0.04–0.10) (fD4.8)−1/2 cm−3 and a shock age of ~(12–42) (fD4.8)1/2 kyr. Based on the data presented here, none of the point sources appears to be the neutron star associated with either SNR.