Search results for "Nucleon"

Meson production inp+U, O+U and S+U interactions at 200 GeV/nucleon

1992

Meson production in proton, oxygen and sulphur interactions with uranium targets at 200 GeV/nucleon is studied. We measure the inclusive meson cross-section d σ/dPT2 and its evolution fromp+U to S+U. The cross-section fitted with an exponential gives an inverse slopePT0 of the order of 210 MeV/c. As a function of the neutral transverse energy,PT0 values show a slight rise followed by a plateau. The normalized difference (σ+−σ−)/σ− between positive and negative meson cross-sections is found to increase withET.

Research on exotic nuclei-experiments at the limits of the nuclear landscape

1999

Experimental progress in studies of exotic nuclei and decay modes near the proton drip line and near the boundary of known neutron-rich nuclei is reviewed with emphasis on recent developments in detector systems and separation techniques.

Photoproduction of π 0 mesons off protons and neutrons in the second and third nucleon resonance regions

2018

Photoproduction of mesons off quasi-free nucleons bound in the deuteron allows to study the electromagnetic excitation spectrum of the neutron and the isospin structure of the excitation of nucleon resonances. The database for such reactions is much more sparse than for free proton targets. Single $\pi^0$ photoproduction off quasi-free nucleons from the deuteron was experimentally studied. Nuclear effects were investigated by a comparison of the results for free protons and quasi-free protons and used as a correction for the quasi-free neutron data. The experiment was performed at the tagged photon beam of the Mainz MAMI accelerator for photon energies between 0.45~GeV and 1.4~GeV, using an…

Proton Inelastic Scattering onNi56in Inverse Kinematics

1994

Inelastic proton scattering to the first excited ${2}^{+}$ state of the doubly magic $^{56}\mathrm{Ni}$ nucleus was investigated in inverse kinematics, using a secondary beam of radioactive $^{56}\mathrm{Ni}$ nuclei. At an incident energy of 101 MeV/nucleon, a value $B(E2,{0}^{+}\ensuremath{\rightarrow}{2}^{+})=600\ifmmode\pm\else\textpm\fi{}120 {e}^{2}$ ${\mathrm{fm}}^{4}$ was measured. This result completes the set of experimental data for the first excited ${2}^{+}$ states in the $1f\ensuremath{-}2p$ shell with a closed shell of neutrons or protons. These data are compared to recent shell-model calculations.

Production and Characterization of the $^{7}$H Resonance

2006

Détecteur MAYA; International audience; The 7H resonance was produced via one-proton transfer reaction between a 8He beam at 15.4A MeV and a 12C gas target. The experimental setup was based on the active-target MAYA which allowed a complete reconstruction of the reaction kinematics. The characterization of the identified 7H events resulted in a resonance energy of 600 keV above the 3H+4n threshold and a resonance width of 100 keV. This study represents the first unambiguous proof of the existence of the 7H state.

Progress and open questions in the physics of neutrino cross sections at intermediate energies

2014

New and more precise measurements of neutrino cross sections have renewed the interest in a better understanding of electroweak interactions on nucleons and nuclei. This effort is crucial to achieve the precision goals of the neutrino oscillation program, making new discoveries, like the CP violation in the leptonic sector, possible. We review the recent progress in the physics of neutrino cross sections, putting emphasis on the open questions that arise in the comparison with new experimental data. Following an overview of recent neutrino experiments and future plans, we present some details about the theoretical development in the description of (anti)neutrino-induced quasielastic scatter…

Suppression of Back-to-Back Hadron Pairs at Forward Rapidity ind+AuCollisions atsNN=200  GeV

2011

Back-to-back hadron pair yields in d + Au and p + p collisions at root S-NN = 200 GeV were measured with the PHENIX detector at the Relativistic Heavy Ion Collider. Rapidity separated hadron pairs were detected with the trigger hadron at pseudorapidity vertical bar eta vertical bar < 0: 35 and the associated hadron at forward rapidity (deuteron direction, 3.0< eta < 3.8). Pairs were also detected with both hadrons measured at forward rapidity; in this case, the yield of back-to-back hadron pairs in d + Au collisions with small impact parameters is observed to be suppressed by a factor of 10 relative to p + p collisions. The kinematics of these pairs is expected to probe partons in the Au nu…

Evidence for Exotic Hadron Contributions toΛb0→J/ψpπ−Decays

2016

A full amplitude analysis of $\Lambda_b^0 \to J/\psi p \pi^-$ decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$. A significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations $N\to p\pi^-$, either the $P_c(4380)^+$ and $P_c(4450)^+\to J/\psi p$ states, previously observed in $\Lambda_b^0 \to J/\psi p K^-$ decays, or the $Z_c(4200)^-\to J/\psi \pi^-$ state, previously reported in $B^0 \to J/\psi K^+ \pi^-$ decays, or all three, are included in the amplitude models. The data support a model containing all three exotic sta…

2021

The fundamental nature of the neutrino is presently a subject of great interest. A way to access the absolute mass scale and the fundamental nature of the neutrino is to utilize the atomic nuclei through their rare decays, the neutrinoless double beta (0νββ) decay in particular. The experimentally measurable observable is the half-life of the decay, which can be factorized to consist of phase space factor, axial vector coupling constant, nuclear matrix element, and function containing physics beyond the standard model. Thus reliable description of nuclear matrix element is of crucial importance in order to extract information governed by the function containing physics beyond the standard m…

Reduced uncertainty of the axial γZ-box diagram correction to the proton’s weak charge

2019

We present the fully up-to-date calculation of the γZ-box correction which needs to be taken into account to determine the weak mixing angle at low energies from parity-violating electron proton scattering. We make use of neutrino and antineutrino inclusive scattering data to predict the parity-violating structure function F3γZ by isospin symmetry. Our new analysis confirms previous results for the axial contribution to the γZ-box graph and reduces the uncertainty by a factor of 2. In addition, we note that the presence of parity-violating photon-hadron interactions induces an additional contribution via F3γγ. Using experimental and theoretical constraints on the nucleon anapole moment we a…