Leptonic ZZ decays in the littlest HiggsHiggs model with T-parity

The littlest $Higgs$ model with T-parity (called the $LHT$ model) predicts the existence of the T-odd leptons, which can generate contributions to some leptonic processes at the one-loop level. We calculate their contributions to the leptonic $Z$ decay processes $Z\to l\bar{l'}$, $Z\to l\bar{l}$, and Z\rightarro \nu\bar{\nu}. We find that the T-odd leptons can give significant contributions to the branching ratios of these decay processes in most of the parameter space. The experimental measurement values might generate constraints on the free parameters of the $LHT$ model.Comment: 16 pages, 8 figures, minor corrections; final version published in Phys.Rev.

Bottom Baryons

Recently CDF and D0 collaborations observed several bottom baryons. In this work we perform a systematic study of the masses of bottom baryons up to $1/m_Q$ in the framework of heavy quark effective field theory (HQET) using the QCD sum rule approach. The extracted chromo-magnetic splitting between the bottom baryon heavy doublet agrees well with the experimental data.Comment: 8 pages, 5 figures, 3 tables. More discussions and references adde

A review of the open charm and open bottom systems

Since the discovery of the first charmed meson in 1976, many open-charm and open-bottom hadrons were observed. In 2003 two narrow charm-strange states $D_{s0}^*(2317)$ and $D_{s1}(2460)$ were discovered by the BaBar and CLEO Collaborations, respectively. After that, more excited heavy hadrons were reported. In this work, we review the experimental and theoretical progress in this field.Comment: Review accepted by Reports on Progress in Physics, 161 pages, 53 figures, 23 tables, more references added and review on heavy baryons adde

HAZ Phase Transformation and Thermal Damage for Laser Remanufacturing a High-Strength Stainless Steel

It briefly introduced laser remanufacturing, which was an advanced repairing method to refabricate damaged components based on laser forming technologies. The possible factors in determining the performance of the laser remanufacturing FV520B were studied by numerical simulation and experimental methods. First, the results of free dilatometry test showed that the volume effect of phase transformations were corresponding to the transformation temperatures and heating rate of the laser process had remarkable effects on the kinetics of phase transformation. In addition, the evolution of temperature fields of the single-pass and multi-layer laser cladding processes were analyzed by numerical simulation method based on deactivate and reactivate element theory. A combined method of dilatometry and metallography was conducted to reveal the effect of cooling condition and phase transformation on the microstructure of HAZ. The maximum temperature of thermal cycle had a dominating effect on the microstructure, microhardness and phase transformation temperature rather than cooling rate. Thermal cycles had a significant effect on the metallographic transformation and consequently decided the mechanical performance. Microhardness and tensile tests were conducted and the results showed that strength and ductility of laser remanufacturing FV520B were equivalent to that of forgings

catena-Poly[[triaqua­(pyridine-κN)nickel(II)]-μ-sulfato-κ2 O:O′]

The title compound, [Ni(SO4)(C5H5N)(H2O)3]n, was synthesized by the hydro­thermal reaction of NiSO4·6H2O, pyridine and water. The central NiII atom is coordinated in a distorted octa­hedral environment by a pyridine N atom, three aqua O atoms and two O atoms of bridging sulfate anions, yielding a zigzag chain. A three-dimensional network is generated via complex hydrogen bonds involving the sulfate and aqua ligands and a pyridine C—H group

Residual Stress Analysis of Laser Remanufacturing

Laser remanufacturing is an advanced repairing method to remanufacture damaged parts based on laser processing, such as laser cladding and laser welding. As a critical factor in determining the remanufacturing quality, residual stress of different laser-remanufactured parts was analysed by numerical methods based on deactivating and reactivating element theory, as well as experimental methods such as X-ray diffraction and hole drilling measurements. The distributions and evolution law of residual stress during multipass laser welding of 7A52 high-strength aluminium alloy, and the effects of forming strategy, heat input and solid-state phase transition on residual stress in the laser cladding forming layers of QT 500 cast iron and FV520B high strength steel, were emphatically studied. The simulation results of residual stress fit well with the experimental results, indicating that both residual stress and its accumulation phenomenon would occur during the laser welding and laser cladding forming, and were affected by factors such as welding pass, heat input and phase transition. It is feasible to control residual stress by using cross path forming strategy, less heat input and alloying power materials with low martensite transition point (Ms)

The Two Phase Transitions of Hydrophobically End-Capped Poly(N-isopropylacrylamide)s in Water

High-sensitivity differential scanning calorimetry (HS-DSC) thermograms of aqueous poly(N-isopropylacrylamide) (PNIPAM) solutions present a sharp unimodal endotherm that signals the heat-induced dehydration/collapse of the PNIPAM chain. Similarly, alpha,omega-di-n-octadecyl-PNIPAM (C18-PN-C18) aqueous solutions exhibit a unimodal endotherm. In contrast, aqueous solutions of alpha,omega-hydrophobically modified PNIPAMs with polycyclic terminal groups, such as pyrenylbutyl (Py-PN-Py), adamantylethyl (Ad-PN-Ad), and azopyridine- (C12-PN-AzPy) moieties, exhibit bimodal thermograms. The origin of the two transitions was probed using microcalorimetry measurements, turbidity tests, variable temperature H-1 NMR (VT-NMR) spectroscopy, and 2-dimensional NOESY experiments with solutions of polymers of molar mass (M-n) from 5 to 20 kDa and polymer concentrations of 0.1 to 3.0 mg/mL. The analysis outcome led us to conclude that the difference of the thermograms reflects the distinct self-assembly structures of the polymers. C18-PN-C18 assembles in water in the form of flower micelles held together by a core of tightly packed n-C18 chains. In contrast, polymers end-tagged with azopyridine, pyrenylbutyl, or adamantylethyl form a loose core that allows chain ends to escape from the micelles, to reinsert in them, or to dangle in surrounding water. The predominant low temperature (T-1) endotherm, which is insensitive to polymer concentration, corresponds to the dehydration/collapse of PNIPAM chains within the micelles, while the higher temperature (T-2) endotherm is attributed to the dehydration of dangling chains and intermicellar bridges. This study of the two phase transitions of telechelic PNIPAM homopolymer highlights the rich variety of morphologies attainable via responsive hydrophobically modified aqueous polymers and may open the way to a variety of practical applications.Peer reviewe