Search results for "Muon"
showing 10 items of 1376 documents
Light vector meson production in pp collisions at s=7 TeV
2012
The ALICE experiment has measured low-mass dimuon production in pp collisions at root s = 7 TeV in the dimuon rapidity region 2.5 < y < 4. The observed dimuon mass spectrum is described as a superposition of resonance decays (eta, rho, omega, eta', phi) into muons and semi-leptonic decays of charmed mesons. The measured production cross sections for omega and phi are sigma(omega)(1 < p(t) < 5 GeV/c. 2.5 < y < 4) = 5.28 +/- 0.54(stat) +/- 0.49(syst) mb and sigma(phi)(1 < p(t) < 5 GeV/c. 2.5 < y < 4) = 0.940 +/- 0.084(stat) +/- 0.076(syst) mb. The differential cross sections d(2)sigma/dy dp(t) are extracted as a function of p(t) for omega and phi. The ratio between the rho and omega cross sec…
Equivalence between local Fermi gas and shell models in inclusive muon capture from nuclei
2005
Motivated by recent studies of inclusive neutrino nucleus processes and muon capture within a correlated local Fermi gas model (LFG), we discuss the relevance of nuclear finite size effects in these reactions at low energy, in particular for muon capture. To disentangle these effects from others coming from the reaction dynamics we employ here a simple uncorrelated shell model that embodies the typical finite size content of the problem. The integrated decay widths of muon atoms calculated with this shell model are then compared for several nuclei with those obtained within the uncorrelated LFG, using in both models exactly the same theoretical ingredients and parameters. We find that the t…
The earth Mantle-Core effect in charge-asymmetries for atmospheric neutrino oscillations
2002
Earth medium effects in the three-neutrino oscillations of atmospheric neutrinos are observable under appropriate conditions. This paper generalizes the study of the medium effects and the possibility of their observation in the atmospheric neutrino oscillations from the case of neutrinos traversing only the Earth mantle, where the density is essentially constant, to the case of atmospheric neutrinos crossing also the Earth core. In the latter case new resonance-like effects become apparent. We calculate the CPT-odd asymmetry for the survival probability of muon neutrinos and the observable muon-charge asymmetry, taking into account the different atmospheric neutrino fluxes, and show the de…
Precision of a data-driven estimate of hadronic light-by-light scattering in the muong−2: Pseudoscalar-pole contribution
2016
Within a dispersive approach to hadronic light-by-light scattering in the muon g-2, the evaluation of the numerically dominant pseudoscalar-pole contribution involves the pseudoscalar-photon transition form factor FPγ*γ*(-Q12,-Q22) with P=π0,η,η′ and, in general, two off-shell photons with spacelike momenta Q1,22. We show that for π0(η,η′), the region of photon momenta below about 1(1.5) GeV gives the main contribution to hadronic light-by-light scattering. We then discuss how the precision of current and future measurements of the single- and double-virtual transition form factor in different momentum regions impacts the precision of a data-driven estimate of this contribution to hadronic …
The radiative return at $\phi$ - and B-factories: small-angle photon emission at next-to-leading order
2002
The radiative return offers the unique possibility for a measurement of the cross section of electron--positron annihilation into hadrons over a wide range of energies. The large luminosity of present phi- and B-factories easily compensates for the additional factor of alpha due to the emission of a hard photon. Final states with photons at large angles can be easily identified. The rate for events with collinear photons, however, is enhanced by a large logarithm and allows, in particular at lower energies, for a complementary measurement. The Monte Carlo generator PHOKHARA, which includes next to leading order corrections from virtual and real photon emission, has been extended from large …
Neutrino oscillation effects on the indirect signal of neutralino dark matter from the Earth core
1999
We investigate the effect induced by neutrino oscillation on the dark matter indirect detection signal which consists in a muon neutrino flux produced by neutralino annihilation in the Earth core. We consider the neutrino oscillation parameters relevant to the atmosferic neutrino deficit, both in the νμ → ντ and νμ → νs cases.
Measurements of Hadronic and Transition Form Factors at BESIII
2019
Motivated by the need of experimental input to improve the Standard Model prediction of the anomalous magnetic moment of the muon aµ, the BESIII Collaboration started a dedicated program to measure hadronic cross sections as well as transition form factors (TFF) with high accuracy. The large data sets acquired by the BESIII Collaboration allow to exploit initial state radiation in order to study hadron production over a wide energy range, as well as two-photon collisions to study the momentum dependence of TFFs in the space like regime. The current status and ongoing investigations in both endeavors are discussed.
Muon (g− 2) in the Standard Model and supersymmetric extensions
2016
Recent new results on the SM and the SUSY prediction for the muon ( g – 2) are briefly reviewed, and a SUSY scenario with particularly large contributions is discussed.
QED one-loop corrections to radiative muon decay
1994
Based upon the Fermi interaction, the differential decay rate of the radiative muon decay including one-loop radiative corrections is determined to the order ${G}_{F}^{2}{\ensuremath{\alpha}}^{2}$. Essential aspects of the calculation are exhibited. After cancellation of IR divergences, the double radiative muon decay is included. Some initial applications are considered.
Observation of Single Top Quark Production
2009
We report observation of the electroweak production of single top quarks in ppbar collisions at sqrt(s) = 1.96 TeV based on 2.3 fb^-1 of data collected by the D0 detector at the Fermilab Tevatron Collider. Using events containing an isolated electron or muon and missing transverse energy, together with jets originating from the fragmentation of b quarks, we measure a cross section of sigma(ppbar -> tb + X, tqb + X) = 3.94 +- 0.88 pb. The probability to measure a cross section at this value or higher in the absence of signal is 2.5 x 10^-7, corresponding to a 5.0 standard deviation significance for the observation.