Search results for "Number"
showing 10 items of 3939 documents
Inclusive D∗-meson production in ep scattering at low Q2 in the GM-VFN scheme at NLO
2009
Abstract We have calculated the next-to-leading order cross sections for the inclusive production of D ∗ -mesons in ep collisions at HERA for finite, although very small Q 2 . In this Q 2 -range, the same approximations as for photoproduction can be used. Our calculation is performed in the general-mass variable-flavour-number scheme. In this approach, large logarithms of the charm transverse momentum are resummed and finite terms depending on m 2 / p T 2 are kept in the hard scattering cross sections. The theoretical results are compared with recent data from the ZEUS Collaboration at HERA. On average, we find good agreement.
Axial resonances in the open and hidden charm sectors
2007
13 pages, 2 figures.-- PACS nrs.: 11.10.St, 11.80.Gw, 12.39.Hg, 12.39.Fe.-- ISI Article Identifier: 000249271600001.-- ArXiv pre-print available at: http://arxiv.org/abs/0704.2314
Hyperons, Charm and Beauty Hadrons: Conclusion and Outlook
2001
In this concluding talk, the advances in the Flavour Problem studies are discussed, following the structure of the presentations in the Conference. The subjects touched are organized as follows: Baryons, K-physics, Charm and Beauty production, Charm and Beauty decays, B-Mixing and CP-Violation, Heavy Quarkonium.
Numerical study of leptogenesis in a 5D split fermion model with bulk neutrinos
2010
We study numerically a 5D hybrid model which incorporates a split fermion scenario and bulk neutrinos. We perform a Monte Carlo analysis of the model in order to find the regions in the parameter space allowing for realization of the leptogenesis. We find that higher order Yukawa terms must be included in order the model to produce a CP violation and net baryon number sufficient for the creation of the observed baryon asymmetry of the Universe.
Determining the Θ+ quantum numbers through the K+p→π+K+n reaction
2004
Abstract We study the K+p→π+K+n reaction with some kinematics suited to the production of the Θ+ resonance recently observed. We show that, independently of the quantum numbers of the Θ+, a resonance signal is always observed in the K+ forward direction. In addition, we also show how a combined consideration of the strength at the peak, and the angular dependence of polarization observables can help determine the Θ+ quantum numbers using the present reaction.
Coherent pion production induced by protons and light ions
1995
Abstract We study coherent pion production by means of the (p,n) and (He,t) reactions on different nuclei and at different energies of the projectile. Energy and angular distributions are calculated. The angular distributions are rather narrow along the direction of the momentum transfer, particularly in heavy nuclei. The reaction is sensitive to the longitudinal part of the elementary NN→NΔ interaction. It also provides a new tool to obtain information on the pion-nuclear interaction, complementary to that offered by reactions with real pions.
Isomer-tagged differential-plunger measurements in proton-unbound 144Ho
2010
The lifetime of an excited state above a weakly populated isomer in the proton-unbound odd-odd nucleus 144Ho has been measured using the recoil distance Doppler shift method. This measurement represents the first differential-plunger lifetime measurement to utilize recoil-isomer tagging. The first excited I[pi]=(10+) state above the two-quasiparticle [pi]h11/2[circle times operator][nu]h11/2(8+) isomer was determined to have a lifetime of [tau]=6(1)�ps. Potential energy surface calculations, based on the configuration-constrained blocking method, predict the isomeric state to have [gamma]-soft triaxial-nuclear shape with [gamma][approximate]24�. The lifetime of the (10+) state can be unders…
Proton spin and the cheshire cat principle
1991
Abstract We discuss the proton matrix element of the flavor-singlet axial current (FSAC), often referred to as proton spin, in terms of the chiral bag model with due account of the axial anomaly and quantum number fractionation. We conclude that the contribution due to gluons is significant for large bag radii and that it is crucial in order to establish the Cheshire cat principle.
A superformula for neutrinoless double beta decay II: The short range part
2000
A general Lorentz-invariant parameterization for the short-range part of the 0vBB decay rate is derived. Combined with the long range part already published this general parameterization in terms of effective B-L violating couplings allows one to extract the 0vBB limits on arbitrary lepton number violating theories.
Hard X-ray emission from neutron star X-ray binaries
2004
Abstract In this paper we review our current knowledge of the hard X–ray emission properties of accreting X–ray Binary Pulsars and old accreting neutron stars in Low Mass X–ray Binaries in light of 7 years of BeppoSAX and RXTE observations. The paper is divided in two parts. In the first part we review the more recent findings on the phase-dependent broad band continua and cyclotron resonance scattering features observed in many systems of the X-ray Binary Pulsar class. In the second part we review the hard X-ray emission of LMXRB focussing on the hard X-ray components extending up to energies of a few hundred keV that have been clearly detected in sources of both the atoll and Z classes. T…