D-term chaotic inflation in supergravity

Even though the chaotic inflation is one of the most popular inflation models for its simple dynamics and compelling resolutions to the initial condition problems, its realization in supergravity has been considered a challenging task. We discuss how the chaotic inflation dominated by the D-term can be induced in supergravity, which would give a new perspective on the inflation model building in supergravity.Comment: 5 pages, to appear in Phys. Rev.

The Decay of the Inflaton in No-scale Supergravity

We study the decay of the inflaton in no-scale supergravity and show that decay due to the gravitational interactions through supergravity effects is highly suppressed relative to the case in minimal supergravity or models with a generic Kahler potential. We also show that decay to gravitinos is suppressed. We demonstrate that decay and sufficient reheating are possible with the introduction of a non-trivial gauge kinetic term. This channel may be dominant in no-scale supergravity, yet yields a re-heating temperature which is low enough to avoid the gravitino problem while high enough for Big Bang Nucleosynthesis and baryogenesis.Comment: Added the footnote in the conclusion section which discusses the constrains on the explicit inflaton couplings to the matter fields via non-renormalizable operators. To appear in JCA

Supersymmetric Musings on the Predictivity of Family Symmetries

We discuss the predictivity of family symmetries for the soft supersymmetry breaking parameters in the framework of supergravity. We show that unknown details of the messenger sector and the supersymmetry breaking hidden sector enter into the soft parameters, making it difficult to obtain robust predictions. We find that there are specific choices of messenger fields which can improve the predictivity for the soft parameters.Comment: 20 pages, 5 figure

Heavy Right-Handed Neutrinos and Dark Matter in the ν\nuCMSSM

We perform a systematic study of the effects of the type-I seesaw mechanism on the dark matter abundance in the constrained supersymmetric standard model (CMSSM) which includes three right-handed neutrinos (the $\nu$CMSSM). For large values of $m_0,m_{1/2}$, we exploit the effects of large neutrino Yukawa couplings on the renormalization group (RG) evolution of the up-type Higgs. In particular, we show that the focus point scale can greatly exceed the electroweak scale resulting in the absence of a focus point region for which the relic density of neutralinos is within the range determined by WMAP. We also discuss the effects of the right-handed neutrinos on the so-called funnel region, where the relic density is controlled by s-channel annihilations through a heavy Higgs. For small values of $m_0,m_{1/2}$, we discuss the possibility of sneutrino coannihilation regions with an emphasis on the suppression of the left-handed slepton doublet masses due to the neutrino Yukawa coupling. We consider two types of toy models consistent with either the normal or inverted hierarchy of neutrino masses.Comment: 18 pages, 7 figures, references and a footnote added, typos correcte

New D-term chaotic inflation in supergravity and leptogenesis

We present a new model of D-term dominated chaotic inflation in supergravity. The F-flat direction present in this model is lifted by the dominant D-term, which leads to chaotic inflation and subsequent reheating. No cosmic string is formed after inflation because the U(1) gauge symmetry is broken during inflation. The leptogenesis scenario via the inflaton decay in our D-term chaotic inflation scenario is also discussed.Comment: 14 pages, no figure, to appear in Phys. Rev.

Cross-correlating the Thermal Sunyaev-Zel'dovich Effect and the Distribution of Galaxy Clusters

We present the analytical formulas, derived based on the halo model, to compute the cross-correlation between the thermal Sunyaev-Zel'dovich (SZ) effect and the distribution of galaxy clusters. By binning the clusters according to their redshifts and masses, this cross-correlation, the so-called stacked SZ signal, reveals the average SZ profile around the clusters. The stacked SZ signal is obtainable from a joint analysis of an arcminute-resolution cosmic microwave background (CMB) experiment and an overlapping optical survey, which allows for detection of the SZ signals for clusters whose masses are below the individual cluster detection threshold. We derive the error covariance matrix for measuring the stacked SZ signal, and then forecast for its detection from ongoing and forthcoming combined CMB-optical surveys. We find that, over a wide range of mass and redshift, the stacked SZ signal can be detected with a significant signal to noise ratio (total S/N \gsim 10), whose value peaks for the clusters with intermediate masses and redshifts. Our calculation also shows that the stacking method allows for probing the clusters' SZ profiles over a wide range of scales, even out to projected radii as large as the virial radius, thereby providing a promising way to study gas physics at the outskirts of galaxy clusters.Comment: 11 pages, 6 figures, 3 tables, minor revisions reflect PRD published versio

A Stochastic Model of Fragmentation in Dynamic Storage Allocation

We study a model of dynamic storage allocation in which requests for single units of memory arrive in a Poisson stream at rate λ and are accommodated by the first available location found in a linear scan of memory. Immediately after this first-fit assignment, an occupied location commences an exponential delay with rate parameter μ, after which the location again becomes available. The set of occupied locations (identified by their numbers) at time t forms a random subset St of {1,2, . . .}. The extent of the fragmentation in St, i.e. the alternating holes and occupied regions of memory, is measured by (St) - |St |. In equilibrium, the number of occupied locations, |S|, is known to be Poisson distributed with mean ρ = λ/μ. We obtain an explicit formula for the stationary distribution of max (S), the last occupied location, and by independent arguments we show that (E max (S) - E|S|)/E|S| → 0 as the traffic intensity ρ → ∞. Moreover, we verify numerically that for any ρ the expected number of wasted locations in equilibrium is never more than 1/3 the expected number of occupied locations. Our model applies to studies of fragmentation in paged computer systems, and to containerization problems in industrial storage applications. Finally, our model can be regarded as a simple concrete model of interacting particles [Adv. Math., 5 (1970), pp. 246–290]

The Earliest Optical Observations of GRB 030329

We present the earliest optical imaging observations of GRB 030329 related to SN 2003dh. The burst was detected by the HETE-2 satellite at 2003 March 29, 11:37:14.67 UT. Our wide-field monitoring started 97 minutes before the trigger and the burst position was continuously observed. We found no precursor or contemporaneous flare brighter than $V=5.1$ ($V=5.5$) in 32 s (64 s) timescale between 10:00 and 13:00 UT. Follow-up time series photometries started at 12:51:39 UT (75 s after position notice through the GCN) and continued for more than 5 hours. The afterglow was $Rc= 12.35\pm0.07$ at $t=74$ min after burst. Its fading between 1.2 and 6.3 hours is well characterized by a single power-law of the form $f{\rm(mJy)} = (1.99\pm0.02{\rm (statistic)}\pm0.14{\rm (systematic)}) \times (t/1 {\rm day})^{-0.890\pm 0.006 {\rm (statistic)}\pm 0.010 {\rm (systematic)}}$ in $Rc$-band. No significant flux variation was detected and upper limits are derived as $(\Delta f/f)_{\rm RMS} = 3-5$% in minutes to hours timescales and $(\Delta f/f)_{\rm RMS} = 35-5$% in seconds to minutes timescales. Such a featureless lightcurve is explained by the smooth distribution of circumburst medium. Another explanation is that the optical band was above the synchrotron cooling frequency where emergent flux is insensitive to the ambient density contrasts. Extrapolation of the afterglow lightcurve to the burst epoch excludes the presence of an additional flare component at $t<10$ minutes as seen in GRB 990123 and GRB 021211.Comment: ApJL, in pres

Parameterizing the Power Spectrum: Beyond the Truncated Taylor Expansion

The power spectrum is traditionally parameterized by a truncated Taylor series: $ln P(k) = ln P_* + (n_*-1) ln(k/k_*) + {1/2} n'_* ln^2(k/k_*)$. It is reasonable to truncate the Taylor series if $|n'_* ln(k/k_*)| << |n_*-1|$, but it is not if $|n'_* ln(k/k_*)| \gtrsim |n_*-1|$. We argue that there is no good theoretical reason to prefer $|n'_*| << |n_*-1|$, and show that current observations are consistent with $|n'_* ln(k/k_*)| ~ |n_*-1|$ even for $|ln(k/k_*)| ~ 1$. Thus, there are regions of parameter space, which are both theoretically and observationally relevant, for which the traditional truncated Taylor series parameterization is inconsistent, and hence it can lead to incorrect parameter estimations. Motivated by this, we propose a simple extension of the traditional parameterization, which uses no extra parameters, but that, unlike the traditional approach, covers well motivated inflationary spectra with $|n'_*| ~ |n_*-1|$. Our parameterization therefore covers not only standard-slow-roll inflation models but also a much wider class of inflation models. We use this parameterization to perform a likelihood analysis for the cosmological parameters.Comment: References added. Typo correcte