Zn Diffusion and α-Fe(Zn) Layer Growth During Annealing of Zn-Coated B Steel

Direct hot press forming of Zn-coated 22MnB5 steels is impeded by micro-cracks that occur in the substrate due to the presence of Zn during the forming process. A study was therefore undertaken to quantify concentration of Zn across the α-Fe(Zn) coating and on grain boundaries in the α-Fe(Zn) layer and the underlying γ-Fe(Zn) substrate after isothermal annealing of Zn-coated 22MnB5 at 1173 K (900 °C) and to link the Zn distribution to the amount and type of micro-cracks observed in deformed samples. Finite difference model was developed to describe Zn diffusion and the growth of the α-Fe(Zn) layer. The penetration of Zn into the γ-Fe(Zn) substrate after 600 seconds annealing at 1173 K (900 °C) through bulk diffusion is estimated to be 3 μm, and the diffusion depth of Zn on the γ-Fe(Zn) grain boundaries is estimated to be 6 μm, which is significantly shorter than the maximum length (15 to 50 μm) of the micro-cracks formed in the severely stressed conditions, indicating that the Zn diffusion into the γ-Fe(Zn) from the α-Fe(Zn) during annealing is not correlated to the depth of micro-cracks. On the other hand, the maximum amount of Zn present in α-Fe(Zn) layer decreases with annealing time as the layer grows and Zn oxidizes, and the amount of Zn-enriched areas inside the α-Fe(Zn) layer is reduced leading to reduced length of cracking. Solid-Metal-Induced Embrittlement mechanism is proposed to explain the benefit of extended annealing on reduced depth of micro-crack penetration into the γ-Fe(Zn) substrate

Renormalization group parameter evolution of the minimal supersymmetric standard model with R-parity violation

A comparison of spectra obtained using the 1-loop MSSM and 2-loop R-parity violating MSSM renormalization group equations is presented. Influence of higher loop corrections and R-parity violating terms is discussed. Some numerical constraints on the R-parity violating parameters are also given.Comment: 4 pages, 1 figure, using RevTE

LHC Signature of Mirage Mediation

We study LHC phenomenology of mirage mediation scenario in which anomaly and modulus contributions to soft SUSY breaking terms are comparable to each other. A Monte Carlo study of mirage mediation, with model parameters $\alpha=1$,$M_0=500$ GeV, $n_M=1/2$, $n_H=1$ and $\rm{tan}\beta=10$, is presented. It is shown that masses of supersymmetric particles can be measured in a model independent way, providing information on SUSY breaking sector. In particular, the mass ratio of gluino to the lightest neutralino for the benchmark scenario is determined to be 1.9 \lesssim m_{\tildeg}/m_{\tilde\chi_1^0} \lesssim 3.1, well reproducing theoretical input value of $m_{\tilde g}/m_{\tilde\chi_1^0} \simeq 2.5$ which is quite distinctive from the predictions $m_{\tilde g}/m_{\tilde\chi_1^0} \gtrsim 6$ of other SUSY scenarios in which gaugino masses are unified at the GUT scale. The model parameters of mirage mediation can be also determined from various kinematic distributions

Broilers fed a low protein diet supplemented with synthetic amino acids maintained growth performance and retained intestinal integrity while reducing nitrogen excretion when raised under poor sanitary conditions

The present study investigated the effects of supplementing a low protein (LP) diet supplemented with key essential amino acids (AA) to broilers on growth performance, intestinal tract function, blood metabolites, and nitrogen excretion when the animals were maintained under various sanitary conditions for 35 D after hatching. Three hundred eighty-four one-day-old male broilers (Ross 308) were randomly allotted to groups that received one of 6 dietary treatments in a 2 × 3 factorial arrangement (i.e., 2 environmental conditions and 3 dietary treatments) to give 8 replicates per treatment. Broilers were challenged with 2 environmental conditions (sanitary vs. poor sanitary). The dietary treatments were (1) high protein (HP) diet, (2) LP diet, and (3) LP diet with synthetic key essential AA (LPA): the LP diet was supplemented with synthetic AA up to the required levels for broilers. On day 14, birds consumed the LP diet impaired growth performance compared with those fed the HP diet, while the average daily weight gain-to-feed conversion ratio of birds fed the LPA diet improved to the level of birds fed the HP diet under poor sanitary conditions (P < 0.05). Broilers raised under poor sanitary conditions and fed the LP diet displayed higher (P < 0.05) zonula occludens (ZO-1) expression on day 14 than broilers fed either the HP or LPA diet. Under sanitary conditions, birds fed HP and LPA diets showed higher villus height and crypt depth compared with those of broilers fed the LP diet on day 35. Moreover, broilers raised in the poor sanitary environment had higher (P < 0.05) serum endotoxins than those raised in the sanitary environment. Broilers fed the LPA diet showed reduced (P < 0.05) nitrogen excretion on days 14 and 35 compared with those fed the LP and HP diets independent of the environment. In conclusion, the LPA diet did not impair growth performance under poor sanitary conditions for 14 D after hatch while resulting in lower nitrogen excretion in any environment conditions throughout the experiment

Penguin and Box Diagrams in Unitary Gauge

We evaluate one-loop diagrams in the unitary gauge that contribute to flavor-changing neutral current (FCNC) transitions involving two and four fermions. Specifically, we deal with penguin and box diagrams arising within the standard model (SM) and in nonrenormalizable extensions thereof with anomalous couplings of the W boson to quarks. We show explicitly in the SM the subtle cancelation among divergences from individual unitary-gauge contributions to some of the physical FCNC amplitudes and derive expressions consistent with those obtained using R_xi gauges in the literature. Some of our results can be used more generally in certain models involving fermions and gauge bosons which have interactions similar in form to those we consider.Comment: 11 pages, 2 figures, to appear in EPJ

Supersymmetry and the positron excess in cosmic rays

Recently the HEAT balloon experiment has confirmed an excess of high-energy positrons in cosmic rays. They could come from annihilation of dark matter in the galactic halo. We discuss expectations for the positron signal in cosmic rays from the lightest superpartner. The simplest interpretations are incompatible with the size and shape of the excess if the relic LSPs evolved from thermal equilbrium. Non-thermal histories can describe a sufficient positron rate. Reproducing the energy spectrum is more challenging, but perhaps possible. The resulting light superpartner spectrum is compatible with collider physics, the muon anomalous magnetic moment, Z-pole electroweak data, and other dark matter searches.Comment: 4 pages, 2 figures, references added, minor wording change

Inclusive J/Psi photoproduction and polarization at HERA in the kt-factorization approach

We investigate the inclusive photoproduction of J/Psi mesons at HERA within the framework of the kt-factorization QCD approach. Our consideration is based on the color singlet model supplemented with the relevant off-shell matrix elements and the CCFM and KMR unintegrated gluon densities in a proton and in a photon. Both the direct and resolved photon contributions are taken into account. Our predictions are compared with the recent experimental data taken by the H1 and ZEUS collaborations. Special attention is put on the J/Psi polarization parameters lambda and nu which are sensitive to the production dynamics.Comment: 21 pages, 15 figure

Super-conservative interpretation of muon g-2 results applied to supersymmetry

The recent developments in theory and experiment related to the anomalous magnetic moment of the muon are applied to supersymmetry. We follow a very cautious course, demanding that the supersymmetric contributions fit within five standard deviations of the difference between experiment and the standard model prediction. Arbitrarily small supersymmetric contributions are then allowed, so no upper bounds on superpartner masses result. Nevertheless, non-trivial exclusions are found. We characterize the substantial region of parameter space ruled out by this analysis that has not been probed by any previous experiment. We also discuss some implications of the results for forthcoming collider experiments.Comment: 10 pages, latex, 3 fig

Implications of the Muon Anomalous Magnetic Moment for Supersymmetry

We re-examine the bounds on supersymmetric particle masses in light of the E821 data on the muon anomalous magnetic moment. We confirm, extend and supersede previous bounds. In particular we find (at one sigma) no lower limit on tan(beta) or upper limit on the chargino mass implied by the data at present, but at least 4 sparticles must be lighter than 700 to 820 GeV and at least one sparticle must be lighter than 345 to 440 GeV. However, the E821 central value bounds tan(beta) > 4.7 and the lighter chargino mass by 690 GeV. For tan(beta) < 10, the data indicates a high probability for direct discovery of SUSY at Run II or III of the Tevatron.Comment: 20 pages LaTeX, 14 figures; references adde

Associated Production of Bottomonia and Higgs Bosons at Hadron Colliders

We study the associated production of bottomonia and Higgs bosons at hadron colliders within the factorization formalism of nonrelativistic quantum chromodynamics providing all contributing partonic cross sections in analytic form. While such processes tend to be suppressed in the standard model, they may have interesting cross sections in its minimal supersymmetric extension, especially at large values of tan(beta), where the bottom Yukawa couplings are enhanced. We present numerical results for the processes involving the lighter CP-even h^0 boson and the CP-odd A^0 boson appropriate for the Fermilab Tevatron and the CERN LHC.Comment: 33 pages, 7 figures, Latex, to appear in Phys. Rev.