Search results for "Observable"
showing 10 items of 634 documents
Centrality dependence of forward J/ψ suppression in high energy proton–nucleus collisions
2015
The production of forward $J/\psi$ mesons in proton-nucleus collisions can provide important information on gluon saturation. In a previous work we studied this process in the Color Glass Condensate framework, describing the target using a dipole cross section fitted to HERA inclusive data and extrapolated to the case of a nuclear target using the optical Glauber model. In this work we study the centrality dependence of the nuclear suppression in this model and compare our results with recent LHC data for this observable.
Generalized parton distributions and hard exclusive reactions
2003
Abstract We discuss how generalized parton distributions (GPDs) enter in a variety of hard exclusive processes such as deeply virtual Compton scattering (DVCS) and hard meson electroproduction reactions on the nucleon. We discuss the links between GPDs and elastic nucleon form factors as well as the information contained in the second moment of GPDs. We subsequently show some key observables which are sensitive to the various hadron structure aspects of the GPDs, and discuss their experimental status.
Measurement ofCPviolation parameters inB0→DK*0decays
2014
An analysis of B0→DK*0 decays is presented, where D represents an admixture of D0 and D¯0 mesons reconstructed in four separate final states: K−π+, π−K+, K+K− and π+π−. The data sample corresponds to 3.0 fb−1 of proton-proton collision, collected by the LHCb experiment. Measurements of several observables are performed, including CP asymmetries. The most precise determination is presented of rB(DK*0), the magnitude of the ratio of the amplitudes of the decay B0→DK+π− with a b→u or a b→c transition, in a Kπ mass region of ±50 MeV/c2 around the K∗(892) mass and for an absolute value of the cosine of the K*0 helicity angle larger than 0.4.
Novel T-Violation observable open to any pair of decay channels at meson factories
2013
Quantum entanglement between the two neutral mesons produced in meson factories has allowed the first indisputable direct observation of Time Reversal Violation in the time evolution of the neutral meson between the two decays. The exceptional meson transitions are directly connected to semileptonic and CP eigenstate decay channels. The possibility of extending the observable asymmetries to more decay channels confronts the problem of the “orthogonality condition”, which can be stated with this tongue-twister: Given a decay channel f , which is the decay channel f′f′ such that the meson state not decaying to f′f′ is orthogonal to the meson state not decaying to f? In this Letter we propose …
Non-decoupling of Heavy Neutrinos and Lepton Flavour Violation
1995
We consider a class of models predicting new heavy neutral fermionic states, whose mixing with the light neutrinos can be naturally significant and produce observable effects below the threshold for their production. We update the indirect limits on the flavour non-diagonal mixing parameters that can be derived from unitarity, and show that significant rates are in general expected for one-loop-induced rare processes due to the exchange of virtual heavy neutrinos, involving the violation of the muon and electron lepton numbers. In particular, the amplitudes for $\mu$--$e$ conversion in nuclei and for $\mu\to ee^+e^-$ show a non-decoupling quadratic dependence on the heavy neutrino mass $M$,…
LAB observables for the muon polarization in K+->pi(+)mu(+)mu(-)
1999
We analyse the muon longitudinal polarization asymmetry \Delta_long in the decay K^+ --> \pi^+ \mu^+ mu^-. It is stressed that, since the muon helicities are not Lorentz-invariant quantities, the magnitude of \Delta_long depends in general on the reference frame. We consider the muon helicities in the LAB system, and study the sensitivity of the longitudinal polarization asymmetry to the flavour-mixing parameters in the Standard Model for stopped and in-flight decaying K^+. A similar analysis is carried out for the decay K_L --> \mu^+ \mu^-. We find that in both cases the asymmetry is diluted when increasing the energy of the decaying kaons.
Neutrino induced coherent pion production off nuclei and the partial conservation of the axial current
2009
15 pages, 7 figures, 1 table.-- PACS nrs.: 25.30.Pt; 12.15.-y; 13.15.+g.-- ArXiv pre-print available at: http://arxiv.org/abs/0903.5285
Neutral current couplings of higher generations
1979
Abstract We show that longitudinal polarization of the outgoing lepton in e + e − →μ + (τ + )μ − (τ − ) is expected at the energies of a vector meson resonance (Ψ, ϒ, T, …). On the basis of the standard SU(2) × U(1) theory, this parity violating observable is already appreciable (∼3%) for the ϒ, and it becomes ∼9% for a T at 30 GeV.
Unified framework for generalized and transverse-momentum dependent parton distributions within a 3Q light-cone picture of the nucleon
2011
We present a systematic study of generalized transverse-momentum dependent parton distributions (GTMDs). By taking specific limits or projections, these GTMDs yield various transverse-momentum dependent and generalized parton distributions, thus providing a unified framework to simultaneously model different observables. We present such simultaneous modeling by considering a light-cone wave function overlap representation of the GTMDs. We construct the different quark-quark correlation functions from the 3-quark Fock components within both the light-front constituent quark model as well as within the chiral quark-soliton model. We provide a comparison with available data and make prediction…
Inclusive and exclusive neutrino-nucleus cross sections and the reconstruction of the interaction kinematics
2021
Abstract We present a full kinematic analysis of neutrino-nucleus charged current quasielastic interactions based on the Local Fermi Gas model and the Random Phase Approximation. The model was implemented in the NEUT Monte Carlo framework, which allows us to investigate potentially measurable observables, including hadron distributions. We compare the predictions simultaneously to the most recent T2K and MINERvA charged current (CC) inclusive, CC0π and transverse kinematic-imbalance variable results. We pursuit a microscopic interpretation of the relevant reaction mechanisms, with the aim to achieving in neutrino oscillation experiments a correct reconstruction of the incoming neutrino kine…