A New Proposal for the Picture Changing Operators in the Minimal Pure Spinor Formalism

Using a new proposal for the "picture lowering" operators, we compute the tree level scattering amplitude in the minimal pure spinor formalism by performing the integration over the pure spinor space as a multidimensional Cauchy-type integral. The amplitude will be written in terms of the projective pure spinor variables, which turns out to be useful to relate rigorously the minimal and non-minimal versions of the pure spinor formalism. The natural language for relating these formalisms is the Cech-Dolbeault isomorphism. Moreover, the Dolbeault cocycle corresponding to the tree-level scattering amplitude must be evaluated in SO(10)/SU(5) instead of the whole pure spinor space, which means that the origin is removed from this space. Also, the Cech-Dolbeault language plays a key role for proving the invariance of the scattering amplitude under BRST, Lorentz and supersymmetry transformations, as well as the decoupling of unphysical states. We also relate the Green's function for the massless scalar field in ten dimensions to the tree-level scattering amplitude and comment about the scattering amplitude at higher orders. In contrast with the traditional picture lowering operators, with our new proposal the tree level scattering amplitude is independent of the constant spinors introduced to define them and the BRST exact terms decouple without integrating over these constant spinors.Comment: 56 pages, typos correcte

Large Electric Dipole Moments of Heavy Leptons

In many models of CP violation, the electric dipole moments (EDMs) of leptons scale as the cube of the lepton mass. In these models, the EDM of a 100 GeV heavy lepton would be a billion times greater than that of the muon, and could be as large as a 0.01 e-fermi. In other models, in which the heavy leptons have different properties from the lighter generations, a similarly large EDM can be obtained. A large EDM could dominate the electromagnetic properties of heavy leptons. The angular distribution and production cross-section of both charged and neutral heavy leptons with large dipole moments is calculated and discussed. The interesting possibility that a heavy neutrino with a large EDM could leave an ionization track in a drift chamber is investigated.Comment: Discussion expanded extensively to include model-dependence of results. Calculations unchanged. Note Added To Acknowledgments: This paper is dedicated to the memory of Nathan Isgu

Pure spinor computation towards open string three-loop

Using the recent results in the pure spinor formulation, we lay out a ground-work towards the full momentum space amplitudes of open superstrings at three-loop. After briefly reviewing the one-loop amplitude, we directly work out the two-loop and reproduce the result that was obtained by a symmetry argument. For the three-loop, first we use the two-loop regulator as a warm-up exercise. The result vanishes. We then employ the regulator that has been recently proposed by Aisaka and Berkovits (AB). It is noted that the terms in higher power in $\frac{1}{\lambda\bar{\lambda}}$ that render the two-loop regulator disqualified for the three-loop do not contribute. This with a few other indications suggests a possibility that the AB regulator might also lead to a vanishing result. Nevertheless, we argue that it is possible to acquire the three-loop amplitude, and present a result that we anticipate to be the three-loop amplitude.Comment: 41 pages, latex, cosmetic change

Pure Spinor Approach to Type IIA Superstring Sigma Models and Free Differential Algebras

This paper considers the Free Differential Algebra and rheonomic parametrization of type IIA Supergravity, extended to include the BRS differential and the ghosts. We consider not only the ghosts lambda's of supersymmetry but also the ghosts corresponding to gauge and Lorentz transformations. In this way we can derive not only the BRS transformations of fields and ghosts but also the standard pure spinor constraints on lambda's. Moreover the formalism allows to derive the action for the pure spinor formulation of type IIA superstrings in a general background, recovering the action first obtained by Berkovits and Howe.Comment: 1+23 pages, v2: added clarifications and a reference, misprints corrected, v3: presentation improved, results unchange

CP violation at colliders

The prospects of experimental detection of $CP$ violation at $e^+e^-$ and $pp/p\overline{p}$ colliders are reviewed. After a general discussion on the quantities which can measure $CP$ violation and on the implications of the $CPT$ theorem, various possibilities of measuring $CP$ violation arising outside the standard model are taken up. $CP$ violation in leptonic processes, especially polarization effects in $e^+e^-\rightarrow l^+l^-$ are discussed next. $CP$ violation in $t\overline{t}$ and $W^+W^-$ production and decay is also described. (Based on talk presented at the WHEPP3, Madras, January 1994).Comment: 20 pages, latex, no figures (only revision is the comment that the article is based on a talk presented at WHEPP3, Madras, January 1994

Free Differential Algebras and Pure Spinor Action in IIB Superstring Sigma Models

In this paper we extend to the case of IIB superstring sigma models the method proposed in hep-th/10023500 to derive the pure spinor approach for type IIA sigma models. In particular, starting from the (Free) Differential Algebra and superspace parametrization of type IIB supergravity, extended to include the BRST differential and all the ghosts, we derive the BRST transformations of fields and ghosts as well as the standard pure spinor constraints for the ghosts $\lambda$ related to supersymmetry. Moreover, using the method first proposed by us, we derive the pure spinor action for type IIB superstrings in curved supergravity backgrounds (on shell), in full agreement with the action first obtained by Berkovits and Howe.Comment: 24 page

Measurement of the τ\tau electric dipole moment using longitudinal polarization of e+e−e^+e^- beams

Certain CP-odd momentum correlations in the production and subsequent decay of $\tau$ pairs in $e^+ e^-$ collisions are enhanced significantly when the $e^+$ and $e^-$ beams are longitudinally polarized. These may be used to probe the real and imaginary parts of $d_\tau^\gamma$, the electric dipole moment of the $\tau$. Closed-form expressions for these ``vector correlations'' and the standard deviation of the operators defining them due to standard model interactions are presented for the two-body final states of $\tau$ decays. If 42\% average polarization of each beam is achieved, as proposed for the tau-charm factories, with equal integrated luminosities for each sign of polarization and a total yield of $2\cdot 10^7$ $\tau^+ \tau^-$ pairs, it is possible to attain sensitivities for $\vert\delta {\rm Re} d_{\tau}^{\gamma}\vert$ of $8\cdot 10^{-19}$, $1\cdot 10^{-19}$, $1\cdot 10^{-19}$ $e$ cm respectively and for $\vert\delta {\rm Im} d_{\tau}^{\gamma}\vert$ of $4\cdot 10^{-14}$, $6\cdot 10^{-15}$, $5\cdot 10^{-16}$ $e$ cm respectively at the three operating center-of-mass energies of 3.67, 4.25 and 10.58 GeV. These bounds emerge when the effects of a posible weak dipole form factor $d_\tau^Z$ are negligible as is the case when it is of the same order of magnitude as $d_\tau^\gamma$. Furthermore, in such a polarization experiment where different polarizations are possible, a model-independent disentangling of their individual effects is possible, and a technique to achieve this is described. A strong longitudinal polarization physics programme at the tau-charm factory appears warranted.Comment: 30 pages, latex, no figure

Decoupling of unphysical states in the minimal pure spinor formalism I

This is the first of a series of two papers where decoupling of unphysical states in the minimal pure spinor formalism is investigated. The multi-loop amplitude prescription for the minimal pure spinor superstring formulated in hep-th/0406055 involves the insertion of picture changing operators in the path integral. These operators are BRST closed in a distributional sense and depend on a number of constant tensors. One can trace the origin of these insertions to gauge fixing, so the amplitudes are formally independent of the constant tensors. We show however by explicit tree-level and one-loop computations that the picture changing operators are not BRST closed inside correlators and the amplitudes do depend on these constant tensors. This is due to the fact that the gauge fixing condition implicit in the existing minimal amplitude prescription is singular and this can lead to Lorentz violation and non-decoupling of BRST exact states. As discussed in hep-th/0406055, a manifestly Lorentz invariant prescription can be obtained by integrating over the constant tensors and in the sequel to this paper, it is shown that when one includes these integrations unphysical states do decouple to all orders despite the fact that the PCO's are not BRST closed inside correlators.Comment: 77 pages (51 pages + appendices), added hyperref

Dipeptidyl Peptidase IV and Incident Diabetes: The Atherosclerosis Risk in Communities (ARIC) study

Dipeptidyl peptidase IV (DPP-IV) is not only important in β-cell function but also has proinflammatory actions. We aimed to investigate whether it could act as a link between low-grade chronic inflammation and diabetes

Racial Differences in Association of Elevated Interleukin-18 Levels With Type 2 Diabetes: The Atherosclerosis Risk in Communities Study

Elevated plasma interleukin-18 (IL-18) has been linked to onset of diabetes mellitus (DM) and its complications. However, so far this association has been shown only in predominantly white populations. We examined IL-18 levels and their association with incident DM in a racially heterogeneous population. In a nested case-cohort design representing a 9-year follow-up of 9,740 middle-aged, initially healthy, nondiabetic white and African American participants of the Atherosclerosis Risk in Communities Study, we selected and measured analytes on race-stratified (50% white, 50% African American) random samples of both cases of incident diabetes (n = 548) and eligible members of the full cohort (n = 536). Baseline IL-18 levels were significantly higher in white participants compared with African American participants (P < 0.001). Although white participants in the fourth (versus first) quartile of IL-18 levels had a significant hazard ratio (HR) for developing DM (HR: 2.1, 95% CI: 1.3-3.4), after adjustment for age, sex, and study center, no difference was seen among African Americans (HR: 1.0, 95% CI: 0.6-1.7). Unlike those in African Americans, IL-18 levels in whites had a significant correlation with age (P < 0.01); anthropometric characteristics such as waist circumference (P < 0.001), height (P = 0.04), waist-to-hip ratio (P < 0.001), and BMI (P < 0.01); and total (P < 0.001) and high-molecular-weight (P < 0.001) adiponectin. There are racial differences in levels of IL-18 and the association of IL-18 with risk factors and incident type 2 DM. In addition, there seems to be a complex interplay of inflammation and adiposity in the development of DM