Search results for "Cross Section"
showing 10 items of 3111 documents
Measurement of double-differential muon neutrino charged-current interactions onC8H8without pions in the final state using the T2K off-axis beam
2016
We report the measurement of muon neutrino charged-current interactions on carbon without pions in the final state at the T2K beam energy using 5.734×1020 protons on target. For the first time the measurement is reported as a flux-integrated, double-differential cross section in muon kinematic variables (cosθμ, pμ), without correcting for events where a pion is produced and then absorbed by final state interactions. Two analyses are performed with different selections, background evaluations and cross-section extraction methods to demonstrate the robustness of the results against biases due to model-dependent assumptions. The measurements compare favorably with recent models which include n…
Measurement of the single π0 production rate in neutral current neutrino interactions on water
2018
The single π0 production rate in neutral current neutrino interactions on water in a neutrino beam with a peak neutrino energy of 0.6 GeV has been measured using the POD, one of the subdetectors of the T2K near detector. The production rate was measured for data taking periods when the POD contained water (2.64×1020 protons-on-target) and also periods without water (3.49×1020 protons-on-target). A measurement of the neutral current single π0 production rate on water is made using appropriate subtraction of the production rate with water in from the rate with water out of the target region. The subtraction analysis yields 106±41±69 signal events where the uncertainties are statistical (stat.…
Exclusive final state hadron observables from neutrino-nucleus multi-nucleon knockout
2020
We present results of an updated calculation of the 2p2h (two particle two hole) contribution to the neutrino-induced charge-current cross section. We provide also some exclusive observables, interesting from the point of view of experimental studies, e.g. distributions of momenta of the outgoing nucleons and of available energy, which we compare with the results obtained within the NEUT generator. We also compute, and separate from the total, the contributions of 3p3h mechanisms. Finally, we discuss the differences between the present results and previous implementations of the model in MC event-generators, done at the level of inclusive cross sections, which might significantly influence …
Recent result from the A2 collaboration at MAMI
2016
The A2 Collaboration at the Mainz Microtron MAMI is measuring photon absorption cross section using circularly and linearly polarized photons up to energies of 1.6 GeV. The photons are produced in the ‘Bremsstrahlungs’ process, the energy is determined by a dedicated tagging system. The Crystal Ball-TAPS detector system with its high capability to cope with multi photon final states is used to acquire data with a variety of nonpolarized and spin polarized targets. Physical goals are the investigation of the nucleons excitation spectrum via single and double meson photoproduction and in addition a detailed determination of meson decays in precision experiments. We have started a program to m…
Production ofWbosons in proton-nucleus collisions
1979
It is shown that nuclear effects can cause an enhancement in the cross section for production of $W$ bosons in a proton-nucleus collision. The cross section near threshold is a few orders of magnitude higher than expected from a linear dependence on the atomic number. Encouraging implications for experiments with fixed targets at laboratory energies of ${10}^{3}$ GeV and higher are discussed. We also discuss lepton-pair production off nuclei.
Measurement of thee+e−→bb¯Cross Section betweens=10.54and 11.20 GeV
2009
We report e;{+}e;{-}-->bb[over ] cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the SLAC PEP-II e;{+}e;{-} collider. A total relative error of about 5% is reached in more than 300 center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the Upsilon(10860) and Upsilon(11020) resonances. In particular we show that their widths may be smaller than previously measured.
Hadronic structure from double parton scattering
2018
In the present paper we consider the so-called effective cross section, a quantity which encodes the experimental knowledge on double parton scattering in hadronic collisions that has been accomulated so far. We show that the effective cross section, under some assumptions close to those adopted in its experimental extractions, can be used to obtain a range of mean transverse distance between an interacting parton pair in double parton scattering. Therefore we have proved that the effective cross section offers a way to access information on the hadronic structure.
Study of the process e+e−→ϕη at center-of-mass energies between 2.00 and 3.08 GeV
2021
We study the process e^+e^− → π^+π^−ηγ, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BABAR data sample with an integrated luminosity of 469 fb^(-1). Using the π^+π^−η invariant mass spectrum, we measure the e^+e^− → π^+π^−η cross section in the e^+e^− center-of-mass energy range from 1.15 to 3.5 GeV. The cross section is well described by the Vector-Meson dominance model with four ρ-like states. We observe 49±9 events of the J/ψ decay to π^+π^−η and measure the product Γ_(J/Ψ → e^+e^−)B_(J/Ψ → π^+π^−η) = 2.34 ± 0.43_(stat) ± 0.16_(syst) eV.
Photodetachment ofH−in the presence of a low-frequency laser field
1993
The photodetachment of a model one-electron ion simulating ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ in the presence of a low-frequency field is analyzed. Two different geometries are considered in order to get information on the effect of the ponderomotive energy shift \ensuremath{\Delta} on the photodetachment cross section. Our calculations suggest that a correspondence may be established between the ponderomotive shift and the photodetachment cross section, when the ejected electron may exchange only a few low-frequency photons. This is in qualitative agreement with recent experimental observations. When a large number of processes are open in which the detached electron may exchange low…
Observation of a cross-section enhancement near mass threshold in e + e - → Λ Λ
2018
The process e(+)e(-) -> Lambda(Lambda) over bar is studied using data samples at root s = 2.2324, 2.400, 2.800 and 3.080 GeV collected with the BESIII detector operating at the BEPCII collider. The Born cross section is measured at root s = 2.2324 GeV, which is 1.0 MeVabove the Lambda(Lambda) over bar mass threshold, to be 305 +/- 45(-36)(+66) pb, where the first uncertainty is statistical and the second systematic. The cross section near threshold is larger than that expected from theory, which predicts the cross section to vanish at threshold. The Born cross sections at root s = 2.400, 2.800 and 3.080 GeV are measured and found to be consistent with previous experimental results, but with…