The quark mass ratio and the η' mass

Within a class of null-plane field theories we show that the Gell-Mann Oakes, Renner value for the quark mass ratio is not inconsistent with the η' mass.     

New value of m(mu)/m(e) from muonium hyperfine splitting

The complete contribution to the muonium hyperfine splitting of relative order alpha(3)(m(e)/m(mu))lnalpha is calculated. The result is much smaller than suggested by a previous estimate and leads to a 2sigma upward shift of the most precise value for the muon-electron mass ratio. Analogous contributions are calculated for the positronium hyperfine splitting, where a discrepancy with experiment remains.     

Masses of the t and the b quark and their mass ratio m b /m t as a consequence of a dynamical breakdown of SU L (2) symmetry

A model (of the type of the Nambu-Jona-Lasinio model) where the t and the b quark simultaneously acquire dynamical masses m _t and m _b is constructed to describe a dynamical breakdown of chiral and weak SU _L(2) symmetry. That the ratio x=m _b/m _t is small may imply that, at high energies, the energy scales of isoscalar vector exchange and isoscalar scalar exchange between the quarks are markedly different $(M_V \sim \sqrt x M_S )$ . The spectrum of composite scalar states of the model and the mechanism that causes the transformation of Goldstone bosons of the system under consideration into components of vector bosons of local SU _L(2) symmetry are investigated.     

Ratio m(c)/m(s) with Wilson fermions

We determine the quark mass ratio m(c)/m(s) on the lattice, using Wilson-type fermions. Configurations with N(f)=2 dynamical clover-improved fermions by the QCDSF Collaboration are used, which were made available through the ILDG. In the valence sector we use a sophisticated, mass-independently O(a)-improved Wilson-type action with small cutoff effects even in the charm mass region. After an extrapolation to the physical pion mass, to zero lattice spacing and to infinite box volume, we find m(c)/m(s)=11.27(30)(26).     

Strange quark mass (ms) dependent model of anisotropic strange quark star

This article presents the configuration of strange quark stars in hydrostatic equilibrium considering the Vaidya-Tikekar metric ansatz.The interior of such stars comprises strange quark matter(henceforth SQM),whose equation of state(henceforth EoS) is described by the MIT EoS p=1/3(ρ-4B),where B is the difference between perturbative and non-perturbative vacuum.We have included the mass of the strange quark(m_s) into the EoS and studied its effect on the overall properties of the stran...     

Strange quark mass from the invariant mass distribution of Cabibbo-suppressed tau decays

Quark mass corrections to the hadronic width play a significant role only for the strange quark. The complete determination of decays into strange hadronic final states performed by ALEPH allows the extraction of the strange spectral function. New results on strange decay modes from other experiments are also incorporated into the present analysis. Using as input moments of the spectral function the analysis leading to the determination of is conducted using reasonable theoretical constraints on the nonperturbative components. Careful attention is paid to the treatment of the perturbative expansions of the moments which exhibit convergence problems. The result obtained, , is stable over the scale from down to about 2 GeV. Its evolution yields and . Received: 22 May 2001 / Published online: 5 November 2001     

Enhanced Sensitivity to Variation of m(e)/m(p) in molecular spectra

We propose new experiments with high sensitivity to a possible variation of the electron-to-proton mass ratio mu identical with m(e)/m(p). We consider a nearly degenerate pair of molecular vibrational levels, each associated with a different electronic potential. With respect to a change in mu, the change in the splitting between such levels can be large both on an absolute scale and relative to the splitting. We demonstrate the existence of such pairs of states in Cs2, where the narrow spectral lines achievable with ultracold molecules make the system promising for future searches for small variations in mu.     

Heavy to light transitions in the heavy quark limit and the determination of |V UB |

We discuss semileptonic decays of heavy mesons into light pseudoscalar and vector mesons. Exploiting the symmetries arising in the heavy quark limit we use the known data on semileptonicD decays to predict the corresponding rates for semileptonicB decays. These consideration may serve as a model independent way to extract theub matrix element of the CKM matrix.Supported by a grant of Deutsche Forschungsgemeinschaft     

Measurement of /V(ub)/ using inclusive B-->X(u)lnu decays with a novel X(u)-reconstruction method

We report the measurement of an inclusive partial branching fraction for charmless semileptonic B decay and the extraction of /V(ub)/. Candidates for B-->X(u)lnu are identified with a novel X(u) reconstruction method based on neutrino reconstruction via missing 4-momentum and a technique called "simulated annealing." Based on 86.9 fb(-1) of data taken with the Belle detector, we obtain DeltaB(B-->X(u)lnu;M(X)<1.7 GeV/c2,q2>8.0 GeV2/c2)=[7.37+/-0.89(stat)+/-1.12(syst)+/-0.55(b-->c)+/-0.24(b-->u)]x10(-4) and determine |V(ub)|=[4.66+/-0.28(stat)+/-0.35(syst)+/-0.17(b-->c)+/-0.08(b-->u)+/-0.58(theory)]x10(-3).     

Determination of the ratior v =d v u v of the valence quark distributions in the proton from neutrino and antineutrino reactions on hydrogen and deuterium

Zeitschrift für Physik C Particles and Fields - A set of proton longitudinal polarized distributions, worked out under the assumption of small gluon polarization, is used to evaluate several...     

OnE0 transitions in the decay of152Eu m (9.3 h)

The conversion electron spectrum of the decay of¹⁵²Eu ^m (9.3 h) has been specially investigated forE0 transitions with the aid of a magnetic spectrometer and coincidence techniques. Besides the knownE0 transitions of 685 keV in¹⁵²Sm and 615 keV in¹⁵²Gd two further pureE0 transitions of 432 keV and 1048 keV have been observed. It is shown that theseE0 transitions are identical with those observed previously in the decay of¹⁵²Tb. NoE0 transitions could be found from a 0⁺ state of 1083 keV in¹⁵²Sm. The measured intensities together with the gamma spectrum measured by Barretteet al. give a consistent decay scheme of¹⁵²Eu ^m . Furthermore the half-life of the 0⁺ level at 615 keV in¹⁵²Gd was measured using the method of “delayed coincidences”. The result was (0.2≦t _1/2≦2.1)×10^?10 s. From this theE0 transition probability for the level was derived as (0.3≦W _K (E0)≦3.7)× 10⁹ s^?1 and theρ-value as 0.10≦¦ρ¦≦0.36. The results are discussed within the framework of the collective model.     

A coupled-channels born-approximation analysis of rare-earth (d,t) transitions

A CCBA (coupled-channels Born approximation) analysis has been performed on a very large set of rare-earth (d, t) transitions. Calculations were performed for states in ¹⁵⁹Gd, ^{161, 163}Dy and ^{165, 167}Er which have been identified as members of rotational bands built on the Nilsson single- hole states $\text{11}\text{2}$^?[505], $\text{1}\text{2}$^?[521], $\text{3}\text{2}$^?[521], $\text{5}\text{2}$^?[523], $\text{5}\text{2}$⁺[642], $\text{5}\text{2}$⁺[633] and $\text{7}\text{2}$⁺[404]. In the cases where the DWBA works well, the CCBA gives results similar to those of DWBA. For the anomalous transitions the CCBA calculations tend to fit better than do the DWBA calculations — but the overall agreement is still rather poor.     

Strange quark mass from pseudoscalar sum rule with O(\alpha_s^4) accuracy

We include the new, five-loop, O(α_s⁴) correction into the QCD sum rule used for the s-quark mass determination. The pseudoscalar Borel sum rule is taken as a study case. The OPE for the correlation function with N⁴LO, O(α_s⁴) accuracy in the perturbative part, and with dimension d≤6 operators reveals a good convergence. We observe a significant improvement of stability of the sum rule with respect to the variation of the renormalization scale after including the O(α_s⁴) correction. We obtain the interval m̄_s(2 GeV)=105±6±7 MeV, which exhibits about 2 MeV increase of the central value, if the O(α_s⁴) terms are removed.