PCAC in Nuclear Medium and the Lovelace-Shapiro-Veneziano formula

A simple way to enforce the Adler zero condition for pion amplitudes in the nuclear medium is to use the Lovelace quantization condition but with modified Regge Slope $\alpha'$ This latter is related to change in the gluon condensate. Increasing nuclear density leads to a relative increase in the Regge Slope $\alpha'$ Denoting this increase by a scale factor $\lambda$, the drop in the $\rho$-mass, $\Delta-N$ mass difference, increase in $\pi\pi$ scattering length, decrease of pion decay constant etc. are simply related to $\lambda$.Comment: 11 pages LATE

A Calculation of Higgs Mass in the Standard Model

The assumption that the ratio of the Higgs self-coupling to the square of its yukawa coupling to the top is (almost) independent of the renormalization scale fixes the Higgs mass within narrow limits at m=160 GeV using only the values of gauge couplings and top mass.Comment: 6 pages, 3 figure

Higgs Mass in the Standard Model from Coupling Constant Reduction

Plausible interrelations between parameters of the standard model are studied. The empirical value of the top quark mass, when used in the renormalization group equations, suggests that the ratio of the colour SU(3) gauge coupling $g_3$, and the top coupling $g_t$ is independent of the renormalization scale. On the other hand, variety of top-condensate models suggest that the Higgs self-coupling $\lambda$ is proportional to $g_t^2$. Invoking the requirement that the ratio $\lambda(t)/g_t^2(t)$ is independent of the renormalization scale $t$, fixes the Higgs mass. The pole mass of the Higgs [which differs from the renormalization group mass by a few percent] is found to be $\sim 154$ GeV for the one-loop equations and $\sim 148$ GeV for the two-loop equations.Comment: 17 pages RevTeX including 7 figure

Anomalies, symmetries and strangeness content of the proton

The matrix elements of the operators of strange quark fields s¯Γ s where Γ is 1 or γ μ γ 5 between a proton state is calculated. The sigma term is found to be ≈ 41 MeV and the SU(3) singlet axial matrix element is found to be ≈ 0.22, both in agreement with experiment. The sigma term is found using the trace anomaly, while the determination of the axial vector current matrix element is from QCD sum rules. These correspond to (ie.943-1) ≈ 0.12 and for the axial current Δ s ≈ -0.12, respectively. The role of the anomalies in maintaining flavor symmetry in the presence of substantial differences in quark masses is pointed out. This suggests that there is no need to invoke an intrinsic strange quark component in the proton wave function

On the Energy Efficiency of LT Codes in Proactive Wireless Sensor Networks

This paper presents an in-depth analysis on the energy efficiency of Luby Transform (LT) codes with Frequency Shift Keying (FSK) modulation in a Wireless Sensor Network (WSN) over Rayleigh fading channels with pathloss. We describe a proactive system model according to a flexible duty-cycling mechanism utilized in practical sensor apparatus. The present analysis is based on realistic parameters including the effect of channel bandwidth used in the IEEE 802.15.4 standard, active mode duration and computation energy. A comprehensive analysis, supported by some simulation studies on the probability mass function of the LT code rate and coding gain, shows that among uncoded FSK and various classical channel coding schemes, the optimized LT coded FSK is the most energy-efficient scheme for distance d greater than the pre-determined threshold level d_T , where the optimization is performed over coding and modulation parameters. In addition, although the optimized uncoded FSK outperforms coded schemes for d < d_T , the energy gap between LT coded and uncoded FSK is negligible for d < d_T compared to the other coded schemes. These results come from the flexibility of the LT code to adjust its rate to suit instantaneous channel conditions, and suggest that LT codes are beneficial in practical low-power WSNs with dynamic position sensor nodes.Comment: accepted for publication in IEEE Transactions on Signal Processin

Adaptive Demodulation in Differentially Coherent Phase Systems: Design and Performance Analysis

Adaptive Demodulation (ADM) is a newly proposed rate-adaptive system which operates without requiring Channel State Information (CSI) at the transmitter (unlike adaptive modulation) by using adaptive decision region boundaries at the receiver and encoding the data with a rateless code. This paper addresses the design and performance of an ADM scheme for two common differentially coherent schemes: M-DPSK (M-ary Differential Phase Shift Keying) and M-DAPSK (M-ary Differential Amplitude and Phase Shift Keying) operating over AWGN and Rayleigh fading channels. The optimal method for determining the most reliable bits for a given differential detection scheme is presented. In addition, simple (near-optimal) implementations are provided for recovering the most reliable bits from a received pair of differentially encoded symbols for systems using 16-DPSK and 16- DAPSK. The new receivers offer the advantages of a rate-adaptive system, without requiring CSI at the transmitter and a coherent phase reference at the receiver. Bit error analysis for the ADM system in both cases is presented along with numerical results of the spectral efficiency for the rate-adaptive systems operating over a Rayleigh fading channel.Comment: 25 pages, 11 Figures, submitted to IEEE Transactions on Communications, June 1, 201

The Gaussian Toeplitz matrix

AbstractAn analytical expression for the LLT decomposition for the Gaussian Toeplitz matrix with elements Tij=[1/(2⧸π)1 ⧸2;σ]exp[-(i-j)2⧸2σ2] is derived. An exact expression for the determinant and bounds on the eigenvalues follows. An analytical expressions for the inverse T-1 is also derived

The derivative of the topological susceptibility at zero momentum and an estimate of η′\eta' mass in the chiral limit

The anomaly-anomaly correlator is studied using QCD sum rules. Using the matrix elements of anomaly between vacuum and pseudoscalars $\pi, eta$ and $\eta'$, the derivative of correlator $chi'(0)$ is evaluated and found to be $\approx 1.82 \times 10^{-3}$ GeV$^2$. Assuming that $\chi'(0)$ has no significant dependence on quark masses, the mass of $\eta'$ in the chiral limit is found to be $\approx$723 MeV. The same calculation also yields for the singlet pseudoscalar decay constant in the chiral limit a value of $\approx 178$ MeV.Comment: LaTeX, 7 pages, 2 figures, uses cernrep.cls (included

Qualitative and Quantitative Detection of Chlamydophila pneumoniae DNA in Cerebrospinal Fluid from Multiple Sclerosis Patients and Controls

A standardized molecular test for the detection of Chlamydophila pneumoniae DNA in cerebrospinal fluid (CSF) would assist the further assessment of the association of C. pneumoniae with multiple sclerosis (MS). We developed and validated a qualitative colorimetric microtiter plate-based PCR assay (PCR-EIA) and a real-time quantitative PCR assay (TaqMan) for detection of C. pneumoniae DNA in CSF specimens from MS patients and controls. Compared to a touchdown nested-PCR assay, the sensitivity, specificity, and concordance of the PCR-EIA assay were 88.5%, 93.2%, and 90.5%, respectively, on a total of 137 CSF specimens. PCR-EIA presented a significantly higher sensitivity in MS patients (p = 0.008) and a higher specificity in other neurological diseases (p = 0.018). Test reproducibility of the PCR-EIA assay was statistically related to the volumes of extract DNA included in the test (p = 0.033); a high volume, which was equivalent to 100 µl of CSF per reaction, yielded a concordance of 96.8% between two medical technologists running the test at different times. The TaqMan quantitative PCR assay detected 26 of 63 (41.3%) of positive CSF specimens that tested positive by both PCR-EIA and nested-PCR qualitative assays. None of the CSF specimens that were negative by the two qualitative PCR methods were detected by the TaqMan quantitative PCR. The PCR-EIA assay detected a minimum of 25 copies/ml C. pneumoniae DNA in plasmid-spiked CSF, which was at least 10 times more sensitive than TaqMan. These data indicated that the PCR-EIA assay possessed a sensitivity that was equal to the nested-PCR procedures for the detection of C. pneumoniae DNA in CSF. The TaqMan system may not be sensitive enough for diagnostic purposes due to the low C. pneumoniae copies existing in the majority of CSF specimens from MS patients