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We have studied the weak kaon production off the nucleon induced by neutrinos at the low and intermediate energies. The studied mechanisms are the main source of kaon production for neutrino energies up to 1.2 to 1.5 GeV for the various channels and the cross sections are large enough to be amenable to be measured by experiments such as MINERvA and T2K.
The Main Injector Particle Production Experiment at Fermilab uses particle beams of charged pions, kaons, proton and anti-proton with beam momenta of 5 to 90 GeV/c and thin targets spanning the periodic table from (liquid) hydrogen to uranium to measure particle production cross sections in a full acceptance spectrometer with charged particle identification for particles from 0.1 to 120 GeV/c using Time Projection Chamber, Time of Flight, multicell Cherenkov, and Ring Imaging Cherenkov detectors and Calorimeter for neutrons. Particle production using 120 GeV/c protons from Main Injector on the MINOS target was also measured. We describe the physics motivation to perform such cross section measurements and highlight the impact of hadronic interaction data on neutrino physics. Recent results on forward neutron cross sections and analysis of MINOS target data are also presented.
The CLEO Experiment, utilizing symmetric e{sup +}e{sup -} collisions provided by the Cornell Electron Storage Ring (CESR) in the charmonium and bottomonium regions, has a wide-reaching program in the study of hadrons and the strong force. This review briefly summarizes recent contributions the CLEO Collaboration has made in the study of: (1) light quark systems (rare decays of the {eta}'); (2) charmonium radiative decays to light quarks (J/{psi} and {psi}(2S) radiative decays to the {eta} and {eta}'); (3) mesons with open charm (the D and D{sub s} decay constants); (4) charmonium transitions (a multipole analysis of {psi}(2S) {yields} {gamma}{chi}{sub c1,2} and {chi}{sub c1,2} {yields} {gamma}J/{psi}); and (5) bottomonium spectroscopy (confirming evidence for the discovery of the {eta}{sub b}(1S)).
We review the approach to modeling soft hadron physics observables based on the Dyson-Schwinger equations of QCD. The focus is on light quark mesons and in particular the pseudoscalar and vector ground states, their decays and electromagnetic couplings. We detail the wide variety of observables that can be correlated by a ladder-rainbow kernel with one infrared parameter fixed to the chiral quark condensate. A recently proposed novel perspective in which the quark condensate is contained within hadrons and not the vacuum is mentioned. The valence quark parton distributions, in the pion and kaon, as measured in the Drell Yan process, are investigated with the same ladder-rainbow truncation of the Dyson-Schwinger and Bethe-Salpeter equations.
The reactions of K{Sigma}(1385) photoproduction, i.e., {gamma}p {yields} K{sup +}{Sigma}{sup 0}(1385) and {gamma} {yields} K{sup +}{Sigma}{sup -}(1385), are investigated in the resonance energy region for studying the role of the nucleon and {Delta} resonances of masses around 2 GeV. The Lagrangians for describing the decays of these resonances into the K{Sigma}(1385) channel are constructed and the decay amplitudes are obtained, which allows us to determine the coupling constants using the predictions of quark models or the data listed by the Particle Data Group. The resulting cross sections are compared to the data from the Thomas Jefferson National Accelerator Facility and the SPring-8, which indicates nontrivial contributions from the two-star-rated resonances in the Particle Data Group as well as from some missing resonances predicted by a quark model.
The energy dependence of the total cross section for the pp {yields} K{sup +}n{Sigma}{sup +} reaction has been investigated at the magnetic spectrometer COSY-ANKE. Signals from the production of the {Sigma}{sup +} hyperon were searched for in three simultaneously measured spectra. The values obtained for the total production cross section {sigma}({Sigma}{sup +}) are slightly below those of {sigma}({Sigma}{sup 0}) at the same excess energies. They follow a phase space dependence and do not show any evidence for strong threshold effects or a significant n{Sigma}{sup +} final state interaction.
The second-order effects (SOE) including a pole contribution of the {Lambda}(1405)({Lambda}*) and range terms on the structure of multi-antikaonic nuclei are investigated in a relativistic mean-field theory coupled with the nonlinear effective chiral Lagrangian. It is shown that, due to the attractive interaction from the {Lambda}*-pole contribution, the K{sup -} mesons and the protons are more attracted each other than the case without the SOE. On the other hand, the density distribution for neutron is pushed outward due to the repulsive effect from the range terms. The SOE on the formation of the bound state of K{sup -} mesons are also discussed associated with modification of relevant kaonic modes in a dense medium.
The precision spectroscopy of kaonic hydrogen and kaonic helium x-rays offers a unique possibility to precisely determine the K{sup -}N strong interaction in the low energy limit. Results and status of modern experiments using silicon drift x-ray detectors (SDDs), namely, KEK E570, SIDDHARTA at DA{Phi}NE and E17 at J-PARC, are discussed.
The KN system at rest makes a sensitive testing ground for low energy QCD. At the DA{Phi}NE electron-positron collider of Laboratori Nazionali di Frascati we study kaonic atoms, taking advantage of the low-energy kaons from {Phi}-mesons decaying nearly at rest. The DEAR (DA{Phi}NE Exotic Atom Research) experiment at LNF delivered the most precise data on kaonic hydrogen up to now. DEAR and its follow-up experiment SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research by Timing Application) are using X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. SIDDHARTA is the first experiment on kaonic helium-3 and deuterium ever, and kaonic hydrogen was remeasured with improved precision.
We will measure the X-rays from kaonic {sup 3}He 3d {yields} 2p transition with a precision below 2 eV. It can provide crucial information on the kaon-nucleus strong interaction. The experiment (J-PARC E17) will be performed as Day-1, which is one of the first experiments in the J-PARC hadron facility in the year 2011. An overview and the present status of the J-PARC E17 experiment are described.
We look for an explanation of the peak in the K{sup +}n invariant mass distribution of the {gamma}d {yields} K{sup +}K{sup -}n p reaction that was associated to the {Theta}{sup +}(1540) pentaquark at LEPS. For this we develop a theoretical model adapted to the experiment. The study shows that the method used in the experiment to associate momenta to the undetected proton and neutron, together with the chosen cuts, necessarily creates an artificial broad peak in the assumed K{sup +}n invariant mass in the region of the claimed {Theta}{sup +}(1540), such that the remaining strength seen for the experimental peak is compatible with a fluctuation of 2{sigma} significance.
The direct emission (DE) and interference (INT) terms of the radiative decay K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{gamma} have been measured by the NA48/2 experiment at CERN SPS. About 6 10{sup 5} K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{gamma} decays have been selected from data collected during 2003 and 2004. The relative amounts of DE and INT with respect to the dominant Inner Bremsstrahlung (IB) contribution have been measured in the range 0<T{sub {pi}}{sup *}<80 MeV, where T{sub {pi}}{sup *} is the kinetic energy of the charged pion in the kaon rest frame, obtaining: Frac(DE) = (3.32 {+-}0.15{sub stat}{+-}0.14{sub syst})10{sup -2}, Frac(INT) = (-2.35 {+-}0.35{sub stat}{+-}0.39{sub syst}) 10{sup -2}. This is the first observation of an interference term in K{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup 0}{gamma} decays. From this measurement the DE normalized electric and magnetic amplitudes are derived: X{sub E} = (-24 {+-}6) GeV{sup -4}, X{sub M} = (254 {+-} 9) GeV{sup -4}.In addition, the CP violating asymmetry in the K{sup +} and K- branching ratios for this channel has been determined to be less than 1.5 10{sup -3} at 90% confidence level.
We present a Regge-inspired effective-Lagrangian framework for neutral-kaon photo-production from the deuteron. Quasi-free kaon production is investigated using the Regge-plus-resonance elementary operator within the relativistic plane-wave impulse approximation. The Regge-plus-resonance model was developed to describe photoinduced and electroinduced charged-kaon production off protons. We show how this elementary operator can be transformed to account for the production of neutral kaons from both protons and neutrons. Our results compare favourably to the sole {sup 2}H({gamma},K{sup 0})YN dataset published to date.
Elastic {pi}N scattering and the reaction {pi}{sup +}p{yields}K{sup +}{Sigma}{sup +} are described simultaneously in a unitary coupled-channels approach which respects analyticity. SU(3) flavor symmetry is used to relate the t- and u- channel exchanges that drive the meson-baryon interaction in the different channels. Angular distributions, polarizations, and spin-rotation parameters are compared with available experimental data. The pole structure of the amplitudes is extracted from the analytic continuation.
The {pi}{sup +}{Sigma}{sup +} and {pi}{sup +}{Xi}{sup 0} scattering lengths were calculated in mixed-action Lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations at four light-quark masses, and at two light-quark masses on the fine MILC configurations. Heavy Baryon Chiral Perturbation Theory with two and three flavors of light quarks was used to perform the chiral extrapolations. To NNLO in the three-flavor chiral expansion, the kaon-baryon processes that were investigated show no signs of convergence. Using the two-flavor chiral expansion for extrapolation, the pion-hyperon scattering lengths are found to be a{sub {pi}}{sup +}{sub {Sigma}}{sup +} = -0.197{+-}0.017 fm, and a{sub {pi}}{sup +}{sub {Xi}}{sup 0} = -0.098{+-}0.017 fm, where the comprehensive error includes statistical and systematic uncertainties.
The latest results on B hadron spectroscopy from the DOe experiment at the Tevatron are presented. The mass measuremen of the B{sub c}{sup -} meson in the B{sub c}{sup -}{yields}J/{psi}{pi}{sup -} decay channel, the observation of excited B{sub s} mesons, the first direct observation of the {Xi}{sub b}{sup -} baryon, and the first observation of the {Omega}{sub b}{sup -} baryon.
We study the dependence of the {pi}{pi} scattering phase shifts on the light quark mass in both standard and unitarized SU(2) Chiral Perturbation Theory (ChPT) to one and two loops. We then use unitarized SU(3) ChPT to study the elastic f{sub 0}(600),{kappa}(800), {rho}(770) and K{sup *}(892) resonances. The quark masses are varied up to values of interest for lattice studies. We find a very soft dependence on the light quark mass of the {pi}{pi} phase shifts at one loop and lightly stronger at two loops and a good agreement with lattice results. The SU(3) analysis shows that the properties of the {rho}(770) and K{sup *}(892) depend smoothly on the quark mass whereas the scalar resonances present a non-analyticity at high quark masses. We also confirm the lattice assumption of quark mass independence of the vector two-meson coupling that, however, is violated for scalars.
A new generation of complete experiments is currently underway with the goal of performing a high precision extraction of pseudoscalar meson photo-production amplitudes. Here we review the most general analytic form of the cross section, dependent upon the three polarization vectors of the beam, target and recoil baryon, including all single, double and triple-polarization terms involving 16 spin-dependent observables. Analytic expressions that determine the recoil baryon polarization are also presented. Different conventions are in use in the literature and we have used a numerical calculation of cross sections from Chew-Goldberger-Low-Nambu amplitudes with arbitrary spin projections to clarify apparent sign differences. As an illustration of the use of this machinery, we carry out a multipole analysis of the {gamma}p {yields} K{sup +}{Lambda} reaction and examine the impact of recently published polarization measurements. In fitting multipoles, we use a combined Monte Carlo sampling of the amplitude space, with gradient minimization, and find a shallow {chi}{sup 2} valley pitted with a very large number of local minima, despite the inclusion of recent data on 8 different observables. We conclude that, while a mathematical solution to the problem of determining an amplitude free of ambiguities may require 8 observables, as has been pointed out in the literature, experiments with realistically achievable uncertainties will require a significantly larger number.