Tests of CPT invariance for neutral flavored meson-antimeson mixing

We focus on two aspects of CPT invariance in neutral meson-antimeson () mixing: (1) tests of CPT invariance, using only the property of ”lack of vacuum regeneration”, which occurs as a part of the well-known Lee-Oehme-Yang (LOY) theory; (2) methods for extracting the CPT-violating mixing parameter through explicit calculations by fully using the LOY-type theory. In the latter context, we demonstrate the importance of the C-even state. In particular, by measuring the time dependence of opposite-sign dilepton events arising from decays of the C-even and C-odd states, may be disentangled from the parameters and characterizing violations of the rule. Furthermore, these two parameters may also be determined. The same is true if one uses like-sign dilepton events arising from only the C-even state. Received: 5 August 2002 / Published online: 25 October 2002 RID="a" ID="a" e-mail: guruv@phy.iitb.ac.in RID="b" ID="b" e-mail: grimus@thp.univie.ac.at     

Information on the dynamics of the reaction KN → K1N from KLN interactions

If $\text{K}{}_{\mathrm{S}}{}^1\text{,}{}_{\mathrm{L}}\text{is a K}{}^1$ resonance decaying into K_S,L (the short- and long-lived kaon) and a neutral system S^o of pions, one can isolate the C-even and C-odd, crossed-channel contributions to $\text{KN → K}{}^1\text{N}$ by using the reactions $\text{K}{}_{\mathrm{L}}\text{N → K}{}_{\mathrm{S}}{}^1\text{,}{}_{\mathrm{L}}\text{N}$ whether S^o is a C-eigenstate, or a mixture of C-even and C-odd states. Applications to the production of K¹(890) and the Q-meson are discussed, and simple numerical predictions made for Q_S,L production. Q-production data indicate approximate t-channel helicity conservation for the ω and P' exchanges at vertices involving a spin change, in similarity to the belief for the pomeron. Q_S,L production data can give information also on Q-decays.     

|η+−| and the reaction e+e− → K0K0 at the φ-resonance

|η_+?| can be rather cleanly determined in e⁺e^?→ K⁰$\text{K}$⁰ at the φ-resonance position from the π⁺π^? time-distribution of decays of one of the produced kaons within a suitable angular portion of a hemisphere. Our procedure is better than the existing methods.     

On linear codes correcting random and low-density burst errors

This paper presents lower and upper bounds on the number of parity-check digits required for a linear code that corrects random errors and errors which are in the form of low-density bursts.     

Polymer nano-encapsulation of templated mesoporous silica monoliths with improved mechanical properties

Macroporous (1–5 μm) monolithic silica aerogels consisting of both random but also ordered mesoporous walls have been synthesized via an acid-catalyzed sol–gel process from tetramethoxysilane (TMOS) using a triblock co-polymer (Pluronic P123) as a structure-directing agent and 1,3,5-trimethylbenzene (TMB) as a micelle-swelling reagent. Pluronic P123 was removed by Soxhlet extraction, and materials in monolithic form were obtained by extracting the pore filling solvent with liquid CO₂, which eventually was taken out supercritically. Although these monoliths are more robust than base-catalyzed silica aerogels of similar density, nevertheless, the mechanical properties can be improved dramatically by letting an aliphatic di-isocyanate (Desmodur N3200) react with the silanols on the macro- and mesoporous surfaces. As it turns out, the polymer fills the mesopores and coats conformally the macropores of templated samples, so that BET surface areas decrease dramatically, from 550–620 m² g^?1 to <5 m² g^?1. By comparison, polymer nano-encapsulation of non-templated acid-catalyzed aerogels preserves a large fraction of their mesoporous surface area, and BET values decrease from 714 m² g^?1 to 109 m² g^?1. Finally, since polymer nano-encapsulation preserves the macroscopic physical dimensions of the monoliths before drying, comparative analysis of the physical dimensions against XRD data of native versus polymer nano-encapsulated samples provides evidence that upon drying macropores (micron size regime) shrink less than mesopores (nanometer size regime).     

CP,T and CPT Invariance in Neutral Kaon Decays

A brief survey of the phenomenology (with emphasis on its present status) of CP, T and CPT invariance in neutral kaon decays is given. Existing limits on the invariances of the mass matrix of the K⁰−K̄⁰ system are stated. Also included are our new results and also those of DASS and KABIR for limits on these invariances for the decay amplitudes, obtained by using existing data, and the available information on the total mass matrix. The CPT invariant part of amplitudes for decay to the I = 0 and I = 2, ππ channels is T (and CP) invariant, in the Eberhard phase convention, to about 0.4% and about 4% respectively; the corresponding T invariant part of these amplitudes is CPT (and CP) invariant to about 1% and about 5% respectively. A limit similar to this last one (5%) was already obtained in the literature by making a further approximation. The CP, T and CPT invariant part of the averaged ΔS = − ΔQ amplitude in K₁₃ decay is found to be less than about 5% of the corresponding ΔS = ΔQ amplitude; the T invariant part of the difference of the averaged ΔS = ΔQ and the averaged ΔS = − ΔQ amplitudes is CPT (and CP) invariant to about 1%. A limit similar to this one (1%) was also obtained in the literature by making a further assumption about the mass matrix. These amplitude limits are expected to have about one significant figure accuracy. Due to large experimental errors, the amplitude limits on the other non-invariance parameters for the above channels are not very good. Difficulties in deriving corresponding parameters for the 3π channel are noted. In certain respects, CPT invariance has been verified experimentally to a poorer accuracy than CP invariance and T invariance.