Search results for "baryon"
showing 10 items of 759 documents
Asymptotic normalization of mirror states and the effect of couplings
2011
Assuming that the ratio between asymptotic normalization coefficients of mirror states is model independent, charge symmetry can be used to indirectly extract astrophysically relevant proton capture reactions on proton-rich nuclei based on information on stable isotopes. The assumption has been tested for light nuclei within the microscopic cluster model. In this work we explore the Hamiltonian independence of the ratio between asymptotic normalization coefficients of mirror states when deformation and core excitation is introduced in the system. For this purpose we consider a phenomenological rotor + N model where the valence nucleon is subject to a deformed mean field and the core is allo…
THE STRUCTURE OF THE NUCLEONS
1980
Electron-proton and electron-deuteron scattering experiments in a wide four momentum range provide information about the structure of the proton and the neutron. The structure is a direct consequence of the hadronic interaction of the nucleon and reveals properties of the strong interaction. Absolute differential cross sections can be expressed in terms of electromagnetic form factors which lead to an understanding of the coupling mechanism between the electromagnetic field and the strongly interacting hadron. The structure can also be discussed in terms of charge densities, but this analysis is strongly restricted by recoil effects. The charge rms radius extracted from recent measurements …
Observation of the decayB¯0→Λc+p¯π0
2010
In a sample of 467 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP- II collider at SLAC we have observed the decay (B) over bar (0) -> Lambda(+)(c)(p) over bar pi(0) and measured the branching fraction to be (1.94 +/- 0.17 +/- 0.14 +/- 0.50 x 10(-4), where the uncertainties are statistical, systematic, and the uncertainty on the Lambda(+)(c) -> pK(-)pi(+) branching fraction, respectively. We determine an upper limit of 1.5 x 10(-6) at 90% C.L. for the product branching fraction B((B) over bar (0) -> Sigma(+)(c) (2455)(p) over bar) x B(Lambda(+)(c) -> pK(-) pi(+)). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon- antibaryo…
Measurements ofB(B¯0→Λc+p¯)andB(B−→Λc+p¯π−)and studies ofΛc+π−resonances
2008
We present an investigation of the decays B-0 -> Lambda(+)(c)(p) over bar and B- -> Lambda(+)(c)(p) over bar pi(-) based on 383 X 10(6)Y(4S) -> B (B) over bar decays recorded with the BABAR detector. We measure the branching fractions of these decays; their ratio is B(B- -> Lambda(+)(c)(p) over bar pi(-))/B((B) over bar (0) -> Lambda(+)(c)(p) over bar) = 15.4 +/- 1.8 +/- 0.3. The B- -> Lambda(+)(c)(p) over bar pi(-) process exhibits an enhancement at the Lambda(+)(c)(p) over bar threshold and is a laboratory for searches for excited charm baryon states. We observe the resonant decays B- -> Sigma(c)(2455)(0)(p) over bar and B- -> Sigma(c)(2800)(0)(p) over bar but see no evidence for B- -> Si…
A polarized 3He target for the photon beam at MAMI
2011
Abstract A polarized 3 He target has been installed for the first time inside the 4 π Crystal Ball detector at the tagged photon beam of the MAinz MIcrotron (MAMI). It has been demonstrated that the system works reliably and that the polarization losses during handling of the polarized gas are under control. Initial polarization values up to 70% and total relaxation times up to 20 h could be obtained during a first test beam time devoted to the measurement of the double polarized photoabsorption cross-section in the Δ ( 1232 ) baryon resonance region.
Longitudinal dynamics of multiple conserved charges
2021
Abstract It is the goal of the RHIC BES program and the future FAIR and NICA facilities to produce compressed baryonic matter. In experiments such as these, strong gradients in baryon density are expected, and therefore the diffusion of baryon number could play a major role in the description of the fireball. The constituents of the produced matter carry a multitude of conserved charges, namely the baryon number, strangeness and electric charge, so that the diffusion currents of conserved charge couple with each other. Therefore, baryon density gradients in the above-mentioned high-density collision experiments will generate equalizing currents in all conserved charges. In common fluid dyna…
A measurement of the b baryon lifetime
1992
In 451 000 hadronic Z0 decays, recorded with the ALEPH detector at LEP, the yields of lambdal- and lambdal+ combinations are measured. Semileptonic decays of b baryons result in a signal of 122 +/- 18(stat.)+22/-23(syst.) lambdal- combinations. From a fit to the impact parameter distribution of the leptons in the lambdal- sample, the lifetime of b baryons is measured to be 1.12+0.32/-0.29(stat.) +/- 0.16(syst.) ps.
Peripheral nucleon-nucleon phase shifts and chiral symmetry
1997
Within the one-loop approximation of baryon chiral perturbation theory we calculate all one-pion and two-pion exchange contributions to the nucleon-nucleon interaction. In fact we construct the elastic NN-scattering amplitude up to and including third order in small momenta. The phase shifts with orbital angular momentum $L\geq2 $ and the mixing angles with $J\geq2$ are given parameterfree and thus allow for a detailed test of chiral symmetry in the two-nucleon system. We find that for the D-waves the $2\pi$-exchange corrections are too large as compared with empirical phase shifts, signaling the increasing importance of shorter range effects in lower partial waves. For higher partial waves…
Performance studies of the P¯ANDA planar GEM-tracking detector in physics simulations
2018
Abstract The P ¯ ANDA experiment will be installed at the future facility for antiproton and ion research (FAIR) in Darmstadt, Germany, to study events from the annihilation of protons and antiprotons. The P ¯ ANDA detectors can cover a wide physics program about baryon spectroscopy and nucleon structure as well as the study of hadrons and hypernuclear physics including the study of excited hyperon states. One very specific feature of most hyperon ground states is the long decay length of several centimeters in the forward direction. The central tracking detectors of the P ¯ ANDA setup are not sufficiently optimized for these long decay lengths. Therefore, using a set of the planar GEM-trac…
Dynamically generatedN*andΛ*resonances in the hidden charm sector around 4.3 GeV
2011
The interactions of $\mathrm{D\ifmmode \bar{}\else \={}\fi{}}{\ensuremath{\Sigma}}_{c}$-$\mathrm{D\ifmmode \bar{}\else \={}\fi{}}{\ensuremath{\Lambda}}_{c}$, ${\mathrm{D\ifmmode \bar{}\else \={}\fi{}}}^{*}{\ensuremath{\Sigma}}_{c}$-${\mathrm{D\ifmmode \bar{}\else \={}\fi{}}}^{*}{\ensuremath{\Lambda}}_{c}$, and related strangeness channels, are studied within the framework of the coupled-channel unitary approach with the local hidden gauge formalism. A series of meson-baryon dynamically generated relatively narrow ${N}^{*}$ and ${\ensuremath{\Lambda}}^{*}$ resonances are predicted around 4.3 GeV in the hidden charm sector. We make estimates of production cross sections of these predicted res…