Anomaly Cancelations in Orientifolds with Quantized B Flux

We consider anomaly cancelations in Type IIB orientifolds on T^4/Z_N with quantized NS-NS sector background B-flux. For a rank b B-flux on T^4 (b is always even) and when N is even, the cancelation requires a 2^{b/2} multiplicity of states in the 59-open string sector. We identify the twisted sector R-R scalars and tensor multiplets which are involved in the Green-Schwarz mechanism. We give more details of the construction of these models and argue that consistency with the 2^{b/2} multiplicity of 59-sector states requires a modification of the relation between the open string 1-loop channel modulus and the closed string tree channel modulus in the 59-cylinder amplitudes.Comment: Revtex 3.0, 34 pages, 2 figures, references adde

Production of Specific Fragments of {varphi}X174 Replicative Form DNA by a Restriction Enzyme from Haemophilus parainfluenzae, Endonuclease HP

A restriction endonuclease from Haemophilus parainfluenzae degrades {varphi}X174 replicative form DNA into eight specific fragments, ranging from 1,700 to 150 base pairs and terminated specifically by deoxycytidylic acid

A note on obstinate tachyons in classical dS solutions

The stabilisation of the dilaton and volume in tree-level flux compactifications leads to model independent and thus very powerful existence and stability criteria for dS solutions. In this paper we show that the sizes of cycles wrapped by orientifold planes are scalars whose scalings in the potential are not entirely model independent, but enough to entail strong stability constraints. For all known dS solutions arising from massive IIA supergravity flux compactifications on SU(3)-structure manifolds the tachyons are exactly within the subspace spanned by the dilaton, the total volume and the volumes of the orientifold cycles. We illustrate this in detail for the well-studied case of the O6 plane compactification on SU(2)xSU(2)/Z_2xZ_2. For that example we uncover another novel structure in the tachyon spectrum: the dS solutions have a singular, but supersymmetric, Minkowski limit, in which the tachyon exactly aligns with the sgoldstino.Comment: 22 pages; v2: added references, minor change

Inflation as a Probe of Short Distance Physics

We show that a string-inspired Planck scale modification of general relativity can have observable cosmological effects. Specifically, we present a complete analysis of the inflationary perturbation spectrum produced by a phenomenological Lagrangian that has a standard form on large scales but incorporates a string-inspired short distance cutoff, and find a deviation from the standard result. We use the de Sitter calculation as the basis of a qualitative analysis of other inflationary backgrounds, arguing that in these cases the cutoff could have a more pronounced effect, changing the shape of the spectrum. Moreover, the computational approach developed here can be used to provide unambiguous calculations of the perturbation spectrum in other heuristic models that modify trans-Planckian physics and thereby determine their impact on the inflationary perturbation spectrum. Finally, we argue that this model may provide an exception to constraints, recently proposed by Tanaka and Starobinsky, on the ability of Planck-scale physics to modify the cosmological spectrum.Comment: revtex, 8 pages, eps figures included, references adde

Heavy Higgs Bosons at 14 TeV and 100 TeV

Searching for Higgs bosons beyond the Standard Model (BSM) is one of the most important missions for hadron colliders. As a landmark of BSM physics, the MSSM Higgs sector at the LHC is expected to be tested up to the scale of the decoupling limit of O(1) TeV, except for a wedge region centered around $\tan\beta \sim 3 -10$, which has been known to be difficult to probe. In this article, we present a dedicated study testing the decoupled MSSM Higgs sector, at the LHC and a next-generation $pp$-collider, proposing to search in channels with associated Higgs productions, with the neutral and charged Higgs further decaying into $tt$ and $tb$, respectively. In the case of neutral Higgs we are able to probe for the so far uncovered wedge region via $pp\to bb H/A \to bbtt$. Additionally, we cover the the high $\tan\beta$ range with $pp\to bb H/A \to bb\tau\tau$. The combination of these searches with channels dedicated to the low $\tan\beta$ region, such as $pp\to H/A \to tt$ and $pp\to tt H/A \to tttt$ potentially covers the full $\tan\beta$ range. The search for charged Higgs has a slightly smaller sensitivity for the moderate $\tan\beta$ region, but additionally probes for the higher and lower $\tan\beta$ regions with even greater sensitivity, via $pp\to tb H^\pm \to tbtb$. While the LHC will be able to probe the whole $\tan\beta$ range for Higgs masses of O(1) TeV by combining these channels, we show that a future 100 TeV $pp$-collider has a potential to push the sensitivity reach up to $\sim \mathcal O(10)$ TeV. In order to deal with the novel kinematics of top quarks produced by heavy Higgs decays, the multivariate Boosted Decision Tree (BDT) method is applied in our collider analyses. The BDT-based tagging efficiencies of both hadronic and leptonic top-jets, and their mutual fake rates as well as the faking rates by other jets ($h$, $Z$, $W$, $b$, etc.) are also presented.Comment: published versio

Unification with Enlarged Kaluza-Klein Dimensions

In minimal theories with extra spatial dimensions at scales mu_0 much lower than the conventional GUT scale, unification can give too-large predictions for alpha_3(M_Z) given alpha_1(M_Z) and alpha_2(M_Z) as empirical input. We systematically study the effects of adding extra states above the compactification scale on running of the gauge couplings and find several simple examples that give unification where all alpha_i(M_Z) are consistent with low-energy data. We study both the supersymmetric and nonsupersymmetric unification.Comment: 18 pages, LaTeX, analysis for the susy case takes into account that extra hypermultiplets come in conjugate pairs, minor changes in text and references, to be published in Phys. Lett.

Phenomenology of 3-Family Grand Unified String Models

In the 3-family grand unified string models constructed so far, there is only one adjoint (and no higher dimensional representation) Higgs field in the grand unified gauge group. In this preliminary analysis, we address the proton-decay problem in the 3-family E_6 and related SO(10) string models. In particular, we analyze the doublet-triplet splitting (within certain assumptions about non-perturbative dynamics). It appears that generically some fine-tuning is necessary to arrange for a pair of Higgs doublets to be light, while having color Higgs triplets superheavy. We also discuss charge-2/3 quark mass matrix that generically also seems to require some fine-tuning to have rank 1.Comment: 12 pages, Revtex 3.0. Minor corrections mad

Brief, Why the Launch Equipment Test Facility Needs a Laser Tracker

The NASA Kennedy Space Center Launch Equipment Test Facility (LETF) supports a wide spectrum of testing and development activities. This capability was originally established in the 1970's to allow full-scale qualification of Space Shuttle umbilicals and T-O release mechanisms. The LETF has leveraged these unique test capabilities to evolve into a versatile test and development area that supports the entire spectrum of operational programs at KSC. These capabilities are historically Aerospace related, but can certainly can be adapted for other industries. One of the more unique test fixtures is the Vehicle Motion Simulator or the VMS. The VMS simulates all of the motions that a launch vehicle will experience from the time of its roll-out to the launch pad, through roughly the first X second of launch. The VMS enables the development and qualification testing of umbilical systems in both pre-launch and launch environments. The VMS can be used to verify operations procedures, clearances, disconnect systems performance &margins, and vehicle loads through processing flow motion excursions