Search results for "[formula omitted] decay"
showing 10 items of 1452 documents
Evidence forB+→J/ψpΛ¯and Search forB0→J/ψpp¯
2003
We have performed a search for the decays ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}p\overline{\ensuremath{\Lambda}}$ and ${B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}p\overline{p}$ in a data set of $(88.9\ifmmode\pm\else\textpm\fi{}1.0)\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\Upsilon}(4S)$ decays collected by the BABAR experiment at the PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ storage ring at the Stanford Linear Accelerator Center. Four charged $B$ candidates have been observed with an expected background of $0.21\ifmmode\pm\else\textpm\fi{}0.14$ events. The corresponding branching fraction is $({12}_{\ensuremath{-}6}^{+9})\ifmmode\times\else\texttimes\fi{}{10}^…
EBIT trapping program
1993
The LLNL electron beam ion trap provides the world's only source of stationary highly charged ions up to bare U. This unique capability makes many new atomic and nuclear physics experiments possible.
Can we measure the neutrino mass hierarchy in the sky?
2010
Cosmological probes are steadily reducing the total neutrino mass window, resulting in constraints on the neutrino-mass degeneracy as the most significant outcome. In this work we explore the discovery potential of cosmological probes to constrain the neutrino hierarchy, and point out some subtleties that could yield spurious claims of detection. This has an important implication for next generation of double beta decay experiments, that will be able to achieve a positive signal in the case of degenerate or inverted hierarchy of Majorana neutrinos. We find that cosmological experiments that nearly cover the whole sky could in principle distinguish the neutrino hierarchy by yielding 'substan…
Non-Bloch decay of transient nutations in S=1/2 systems: An experimental investigation.
1993
The decay of transient nutations has been experimentally investigated in S=1/2 spin systems at microwave frequency: E' centers in silica and [${\mathrm{AlO}}_{4}$${]}^{0}$ centers in quartz have been studied. We have found that the damping is well described by a single exponential decay function, as expected from a ${\mathit{T}}_{1}$-${\mathit{T}}_{2}$ model (Bloch model). However, the agreement is only qualitative. In fact the measured decay rate \ensuremath{\Gamma} is faster than expected and depends on the driving-field amplitude: it tends to the Bloch value ${\mathrm{\ensuremath{\Gamma}}}_{\mathit{B}}$=1/2${\mathit{T}}_{2}$ in the low-power limit and becomes faster and faster on increas…
Polarizability of the neutron
1990
Abstract A first measurement of quasi-free Compton scattering by the neutron bound in the deuteron has yielded a value for the polarizability of the neutron of αn=(11.7 −11.7+4.3)×10 −4fm 3. This means that a finite value for the polarizability has been obtained, though the result is still consistent with zero. The π0 decay constant Fπ 0γγ and the pion nucleon coupling constant gNNπ have opposite signs.
Mesonic enhancement of the weak axial charge and its effect on the half-lives and spectral shapes of first-forbidden J+↔J− decays
2018
The effects of the enhancement of the axial-charge matrix element γ5 were studied in medium heavy and heavy nuclei for first-forbidden J+↔J− decay transitions using the nuclear shell model. Noticeable dependence on the enhancement ϵMEC of the axial-charge matrix element, as well as on the value of the axial-vector coupling constant gA was found in the spectral shapes of $^{93}$Y, $^{95}$Sr, and $^{97}$Y. The importance of the spectrum of $^{138}$Cs in the determination of gA is discussed. Half-life analyses in the A≈95 and A≈135 regions were done, and consistent results gA≈0.90, 0.75, and 0.65, corresponding to the three enhancement scenarios ϵMEC=1.4, 1.7, and 2.0, were obtained. Connectio…
Extracting information on the decays from the decays
2005
Abstract We have analyzed the relation between the two-neutrino ( 2 ν β β ) and neutrinoless ( 0 ν β β ) double beta decays of 76Ge, 82Se, 100Mo, and 116Cd. The relevant nuclear matrix elements have been calculated by using the proton–neutron quasiparticle random-phase approximation (pn-QRPA) with realistic two-body interactions. The dependence of the calculated matrix elements on the strength g pp of the particle–particle part of the proton–neutron two-body interaction is investigated. Recently a procedure was proposed where data on 2 ν β β -decay half-lives could be used to derive appropriate values of g pp for calculating the 0 ν β β -decay matrix elements. Following this procedure, we h…
Nuclear matrix elements for Majoron emitting double-$\beta$ decay
2021
A complete calculation of the nuclear matrix elements (NMEs) for Majoron emitting neutrinoless double beta decay within the framework of IBM-2 for spectral indices $n=1,3,7$ is presented. By combining the results of this calculation with previously calculated phase-space factors (PSFs) we give predictions for expected half-lives. By comparing with experimental limits on the half-lives we set limits on the coupling constants $\ensuremath{\langle}{g}_{ee}^{M}\ensuremath{\rangle}$ of all proposed Majoron-emitting models.
Pentaquark decay width in QCD sum rules
2005
In a diquark-diquark-antiquark picture of the pentaquark we study the decay $\Theta \rightarrow K^{+} n$ within the framework of QCD sum rules. After evaluation of the relevant three-point function, we extract the coupling $g_{\Theta nK}$ which is directly related to the pentaquark width. Restricting the decay diagrams to those with color exchange between the meson-like and baryon-like clusters reduces the coupling constant by a factor of four. Whereas a small decay width might be possible for a positive parity pentaquark, it seems difficult to explain the measured width for a pentaquark with negative parity.
Study of high-multiplicity three-prong and five-prong τ decays at BABAR
2012
We present measurements of the branching fractions of three-prong and five-prong tau decay modes using a sample of 430 million tau lepton pairs, corresponding to an integrated luminosity of 468 fb(-1), collected with the BABAR detector at the PEP-II asymmetric-energy e_e storage rings at SLAC National Accelerator Laboratory. The tau(-) -> (3 pi)(-) eta nu(tau), tau(-) -> (3 pi)(-) omega nu(tau), and tau(-) f(1) (1285)nu(tau) branching fractions are presented, as well as a new limit on the branching fraction of the second-class current decay tau(-) -> pi(-) eta'(958)nu(tau). We search for the decay mode tau(-) -> K- eta'(958)nu(tau) and for five-prong decay modes with kaons, and place the fi…