Vector Meson Decay of Baryon Resonances

We investigate the coupling of vector mesons with nucleons to nucleon resonances in an isospin-selective VMD approach and explore the in-medium properties of vector mesons.Comment: 8 pages, 2tables, 4 figures, invited talk at NSTAR 2001, Workshop on the Physics of Excited Nucleons, University of Mainz, Germany, March 7-10, 2001. To be published in World Scientifi

Vector Mesons and Baryon Resonances in Nuclear Matter

We calculate the effect of many-body interactions in nuclear matter on the spectral function of $\rho$ and $\omega$ meson. In particular, we focus on the role played by baryon resonances in this context.Comment: 4 pages, 4 figures, to be published in proceedings of the Third International Conference on Perspectives on Hadronic Physics, 7 - 11 May 2001, Miramare-Trieste, Ital

Coupling of Baryon Resonances to the NωN \omega channel

We estimate the resonance coupling strength $f_{RN\omega}$ and $f_{RN\rho}$ from a Vector Meson Dominance (VMD) analysis. The isoscalar and isovector part of the photon coupling are obtained separately from helicity amplitudes. The reliability of this approach is tested by comparing VMD predictions for $f_{RN\rho}$ with values obtained from fitting the hadronic decay widths into $N \rho$. A reasonable agreement is found, but VMD tends to underestimate the coupling constants. In order to confirm consistency with experimental data, we calculate the cross-sections for photon-and pion induced reactions within a {\it Breit-Wigner} model. Finally, we study how the properties of $\omega$ mesons in nuclear matter are affected from the excitation of resonance-hole loops. For an $\omega$ at rest, we find a broadening of about 40 MeV, while at higher momenta the effect of resonance excitations is reduced.Comment: 21 pages, 5 ps figures, misprints corrected, discussion added, improved calculation of gamma N -> omega N, revised version to be published in Nuclear Physics

Hadronic Spectral Functions in Nuclear Matter

We study the in-medium properties of mesons $(\pi,\eta,\rho)$ and baryon resonances in cold nuclear matter within a coupled-channel analysis. The meson self energies are generated by particle-hole excitations. Thus multi-peak spectra are obtained for the mesonic spectral functions. In turn this leads to medium-modifications of the baryon resonances. Special care is taken to respect the analyticity of the spectral functions and to take into account effects from short-range correlations both for positive and negative parity states. Our model produces sensible results for pion and $\Delta$ dynamics in nuclear matter. We find a strong interplay of the $\rho$ meson and the $D_{13}(1520)$, which moves spectral strength of the $\rho$ spectrum to smaller invariant masses and leads to a broadening of the baryon resonance. The optical potential for the $\eta$ meson resulting from our model is rather attractive whereas the in-medium properties modifications of the $S_{11}(1535)$ are found to be quite small.Comment: 71 pages, 31 figures, accepted for Publication in Nuclear Physics A; minor modifications of the manuscript, several typos correcte

The Spectral Function of the Rho Meson in Nuclear Matter

We calculate the modification of a rho meson in nuclear matter through its coupling to resonance-hole states. Starting from a recently proposed model, we include all four star resonances up to 1.9 GeV. In contrast to previous works, we include not only resonances that couple to the rho in a relative p-wave, but also those that couple to an s-wave state. In addition, we solve the equation for the rho spectral function self-consistently. We find that s-wave resonances affect the in medium spectral function of the rho strongly. In the transverse channel the rho meson is, especially at non zero momentum, completely washed out and can in the presence of nuclear matter no longer be viewed as a resonant excitation of the vacuum. Instead, our model shows a continuum of possible excitations with the quantum numbers of a transversely polarized rho. In the longitudinal channel, however, the rho retains its resonant character in our calculation. As a consequence of the self-consistent treatment we also find a strong enhancement of the widths of the included nucleon resonances in medium.Comment: 27 pages, LaTex, 15 figures using epsfig.sty, submitted to Nuclear Physics A. Typos corrected in eq. (28) and table

Under-performance of listed companies? Real earnings management and M&A: chinese empirical evidence

Purpose: The purpose of this paper is to examine whether acquiring firms attempt to adopt real earnings management strategy to upward reported earnings in the period of M&A announcement and provide an explanation for the underperformance of post-M&A in share payment M&A affairs occurring in China’s capital market from 2008-2010. Design/methodology/approach: The author uses Roychowdhury’s(2006) methodology to measure the magnitude of real earnings management of acquiring firms in stock for stock M&A by exploiting financial date from 2006 to 2011. The methodology includes three models, which are cash ?ow from operations, production costs and discretionary expenditures, respectively. Findings: It was found that firms using stock as a financing medium exhibit significant negative abnormal cash flows and abnormal discretionary expenses yet abnormal production costs significantly positive during the current period of M&A. Moreover, it was also documented that acquiring firms use real activities manipulation to overstate earnings for the purpose of improving market confidence. Finally, a negative association was found between REM and under-performance of post-M&A. Research limitations/implications: To some extent, these results explain the puzzle of performance decline over the following period of post-M&A. Meanwhile, our study adds to prior literature that capital market pressures induce acquiring firms inflate reported earnings by manipulating real activities in stock-financed M&A occurring in China’s capital market. Practical implications: The author’s result imply that investors, analysts and regulators cannot ignore more undetectable opportunism behaviors underlying reported earnings than accrual-based earnings management and the impact on the performance of post-M&A when they use financial statements to evaluate acquiring firms. Social implications: Our study plays important role in making public policies. Furthermore, it is necessary to improve outside supervisory mechanism and strengthen construction of honesty and faithfulness so as to realize the main purpose of value creation in M&A. Originality/value: The paper extends prior literature by taking a closer look at acquiring firms’ managerial myopia behavior in stock-financed M&A. The administrators of acquiring firms have strong incentives to manage earning upward by adopting a more subtle way which is a costly means because it has value-destroying effect on performance of post-M&A.Peer Reviewe

Innovation as Determining Factor of Post-M&A Performance: The Case of Vietnam

This research aims to communicate new results of empirical investigations to learn about the relationship between determination of controlling an acquired firm’s capital, assets and brand versus its capability of innovation and ex post performance of Vietnam’s M&A industry in the 2005-2012 period. The analysis employs a categorical data sample, consisting of 212 M&A cases, and performs a number of logistic regressions with significant results being reported on relationships between pre-M&A strategic pursuit of innovation (versus capital/physical assets) of the acquired and post-M&A performance. In addition, pre-M&A capital expenditures tend to cause poor post-M&A performance. As a general conclusion, this study shows that creative performance can be a factor to pursue in M&A transactions, which suggests the need to emphasize capable and willing human capital. However, in a wave of M&A where there is an overwhelming emphasis on assets and brands, the innovation factor’s impact is limited

On the nature of the extragalactic number counts in the K-band

We investigate the causes of the different shape of the $K$-band number counts when compared to other bands, analyzing in detail the presence of a change in the slope around $K\sim17.5$. We present a near-infrared imaging survey, conducted at the 3.5m telescope of the Calar Alto Spanish-German Astronomical Center (CAHA), covering two separated fields centered on the HFDN and the Groth field, with a total combined area of $\sim0.27$deg$^{2}$ to a depth of $K\sim19$ ($3\sigma$,Vega). We derive luminosity functions from the observed $K$-band in the redshift range [0.25-1.25], that are combined with data from the references in multiple bands and redshifts, to build up the $K$-band number count distribution. We find that the overall shape of the number counts can be grouped into three regimes: the classic Euclidean slope regime ($d\log N/dm\sim0.6$) at bright magnitudes; a transition regime at intermediate magnitudes, dominated by $M^{\ast}$ galaxies at the redshift that maximizes the product $\phi^{\ast}\frac{dV_{c}}{d\Omega}$; and an $\alpha$ dominated regime at faint magnitudes, where the slope asymptotically approaches -0.4($\alpha$+1) controlled by post-$M^{\ast}$ galaxies. The slope of the $K$-band number counts presents an averaged decrement of $\sim50$ in the range $15.5<K<18.5$ ($d\log N/dm\sim0.6-0.30$). The rate of change in the slope is highly sensitive to cosmic variance effects. The decreasing trend is the consequence of a prominent decrease of the characteristic density $\phi^{\ast}_{K,obs}$ ($\sim60$ from $z=0.5$ to $z=1.5$) and an almost flat evolution of $M^{\ast}_{K,obs}$ (1$\sigma$ compatible with $M^{\ast}_{K,obs}=-22.89\pm0.25$ in the same redshift range).Comment: 18 pages, 22 figures, Accepted by Astronomy & Astrophysic