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In this paper we investigate methods to study the t[bar.t] Higgs coupling. The spin and CP properties of a Higgs boson are analysed in a model-independent way in its associated production with a t[bar.t] pair in high-energy [e.sup.+] [e.sup.-] collisions. We study the prospects of establishing the CP quantum numbers of the Higgs boson in the CP-conserving case as well as those of determining the CP-mixing if CP is violated. We explore in this analysis the combined use of the total cross section and its energy dependence, the polarisation asymmetry of the top quark and the up-down asymmetry of the antitop with respect to the top-electron plane. We find that combining all three observables remarkably reduces the error on the determination of the CP properties of the Higgs Yukawa coupling. Furthermore, the top polarisation asymmetry and the ratio of cross sections at different collider energies are shown to be sensitive to the spin of the particle produced in association with the top-quark pair.

We explore the prospects for observing CP violation in the minimal supersymmetric extension of the Standard Model (MSSM) with six CP-violating parameters, three gaugino mass phases and three phases in trilinear soft supersymmetry-breaking parameters, using the CPsuperH code combined with a geometric approach to maximise CP-violating observables subject to the experimental upper bounds on electric dipole moments. We also implement CP-conserving constraints from Higgs physics, flavour physics and the upper limits on the cosmological dark matter density and spin-independent scattering. We study possible values of observables within the constrained MSSM (CMSSM), the non-universal Higgs model (NUHM), the CPX scenario and a variant of the phenomenological MSSM (pMSSM). We find values of the CP-violating asymmetry A CP in b → s γ decay that may be as large as 3 %, so future measurements of A CP may provide independent information about CP violation in the MSSM. We find that CP-violating MSSM contributions to the B s meson mass mixing term Δ M B s are in general below the present upper limit, which is dominated by theoretical uncertainties. If these could be reduced, Δ M B s could also provide an interesting and complementary constraint on the six CP-violating MSSM phases, enabling them all to be determined experimentally, in principle. We also find that CP violation in the h 2 , 3 τ + τ - and h 2 , 3 t ¯ t couplings can be quite large, and so may offer interesting prospects for future p p , e + e - , μ + μ - and γ γ colliders.

The electromagnetic radiation emitted by colliding beams is expected to play an important role at the next generation of high energy e+e- linear colliders. Focussing on the simplest process, e+e-→μ+μ-, we show that, for suitable machine parameters and luminosity, radiative effects like initial state radiation (ISR) and beamstrahlung can be used to search for resonant graviton modes of the Randall–Sundrum model in an efficient manner.

We present a Next-to-Leading Order calculation of the cross section for the leptoproduction of large-$E_{\\\bot}$ hadrons and we compare our predictions with H1 data on the forward production of $\\\pi^0$. We find large higher order corrections and an important sensitivity to the renormalization and factorization scales. These large corrections are shown to arise in part from BFKL-like diagrams at the lowest order.

We report the synthesis of Th1–xMnxO2 (x = 0, 0.001, 0.002, 0.004, and 0.01 wt%) nanoparticles by the urea combustion method using thorium nitrate gel followed by heat treatment at a higher temperature (T). The obtained Th1–xMnxO2 nanocrystals were characterized by x-ray diffraction (XRD), direct-current magnetization (M) measurements and electron paramagnetic resonance (EPR). XRD analysis revealed that Th1–xMnxO2 crystallizes in the cubic structure (Fm3m). M measurements showed ferromagnetic ordering at room temperature for Th0.99Mn0.01O2 samples annealed at 775 K. An intense and broad ferromagnetic resonance (FMR) having linewidth of ∼1200 G, was observed at relatively lower fields in the EPR spectra of Th0.99Mn0.01O2 samples annealed at 775 K, indicating the presence of a ferromagnetic phase at room temperature. EPR measurements were used to estimate the number of spins involved in the ferromagnetic ordering. Out of the total Mn present in Th0.99Mn0.01O2 samples, about 25% of the Mn2+ ions were found to be responsible for the ferromagnetic ordering. In addition to the FMR signal, a weak hyperfine sextet was observed at g = 2.0048 (55Mn, I = 5/2), which corresponds to the −1/2 ↔ +1/2 transition of Mn2+ ions, suggesting its presence at thorium sites (uncoupled spins). X-ray photoelectron spectra indicated that the manganese ions exist mainly as Mn2+, Mn3+, and Mn4+. The room-temperature ferromagnetism may be attributed to the coupling between these Mn2+ ions at thorium sites in ThO2 rather than due to the formation of any metastable secondary phases.

We report the synthesis of Th 1– x Mn x O 2 ( x = 0, 0.001, 0.002, 0.004, and 0.01 wt%) nanoparticles by the urea combustion method using thorium nitrate gel followed by heat treatment at a higher temperature ( T ). The obtained Th 1– x Mn x O 2 nanocrystals were characterized by x-ray diffraction (XRD), direct-current magnetization ( M ) measurements and electron paramagnetic resonance (EPR). XRD analysis revealed that Th 1– x Mn x O 2 crystallizes in the cubic structure ( Fm 3 m ). M measurements showed ferromagnetic ordering at room temperature for Th 0.99 Mn 0.01 O 2 samples annealed at 775 K. An intense and broad ferromagnetic resonance (FMR) having linewidth of ∼1200 G, was observed at relatively lower fields in the EPR spectra of Th 0.99 Mn 0.01 O 2 samples annealed at 775 K, indicating the presence of a ferromagnetic phase at room temperature. EPR measurements were used to estimate the number of spins involved in the ferromagnetic ordering. Out of the total Mn present in Th 0.99 Mn 0.01 O 2 samples, about 25% of the Mn 2+ ions were found to be responsible for the ferromagnetic ordering. In addition to the FMR signal, a weak hyperfine sextet was observed at g = 2.0048 ( 55 Mn, I = 5/2), which corresponds to the −1/2 ↔ +1/2 transition of Mn 2+ ions, suggesting its presence at thorium sites (uncoupled spins). X-ray photoelectron spectra indicated that the manganese ions exist mainly as Mn 2+ , Mn 3+ , and Mn 4+ . The room-temperature ferromagnetism may be attributed to the coupling between these Mn 2+ ions at thorium sites in ThO 2 rather than due to the formation of any metastable secondary phases.

Effect of gamma irradiation on protein metabolism has been studied in four species of Drosophilidae. The following developmental stages of each species were irradiated at 27°C at a dose rate of 15 rads per second over a period of 2 min: egg, third-instar larva, three pupal stages, freshly emerged imago. It has been observed that in most cases irradiation caused considerable degradation of protein. Developmental stages showing maximal and minimal radiosensitivity differ in the species observed. Thus, the relative radiosensitivity of a particular developmental stage is found to be species specific. Under the conditions of these experiments, the imagines of D. melanogaster and D. malerkotliana were not radiosensitive as shown by postirradiation increase in their protein content.