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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Study of the {gamma}d {yields} K{sup +}K{sup -}np reaction and an alternative explanation for the ''{Theta}{sup +}'' peak

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.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Differential cross sections and spin density matrix elements for {gamma}p {yields} {phi}p from CLAS

Preliminary differential cross-sections and the {rho}{sub MM'}{sup 0} spin density matrix elements (SDME) for the reaction {gamma}{rho} {yields} {phi}p for both charged-({phi} {yields} K{sup +}K-) and neutral-mode ({phi} {yields} K{sub L}{sup 0}K{sub S}{sup 0}) topologies obtained from CLAS are presented. Our kinematic coverage is from near production threshold ({radical}(s){approx}1.97 GeV) to ({radical}(s) 2.84 GeV), with a wide coverage in the production angle. As seen in previous LEPS results, the differential cross-sections show a localized 'bump' between ({radical}(s){approx}2 and 2.2 GeV that is not expected from a simple Pomeron exchange picture. Comparisons between the charged- and neutral-mode results and possible effects from the K{sup +}{Lambda}(1520) channel are discussed. Our SDME results confirm the well-known deviations from t-channel helicity conservation (TCHC) for Pomeron exchange, but s-channel helicity conservation (SCHC) is also seen to be broken.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Spectroscopic study of {Lambda}(1405) via the in-flight (K{sup -},n) reaction on deuteron

We present an experimental study of {Lambda}(1405) via the in-flight (K{sup -},n) reaction on the deuteron target (J-PARC E31). We will measure all {Sigma}{sup +}{pi}{sup -}, {Sigma}{sup -}{pi}{sup +} and {Sigma}{sup 0}{pi}{sup 0} final states so that the isospin structure of the produced hyperon resonance state can be decomposed. In this report, we present an overview of the experiment and preparation status.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Effect of {Lambda}(1405) on structure of multi-antikaonic nuclei

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.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Incoherent {phi} photo-production from deuteron in SPring-8/LEPS

We present measurements of differential cross sections and decay asymmetries of incoherent {phi}-meson photo-production from the deuteron at forward angles using linearly polarized photons beam in energy range from the production threshold to E = 2.4 GeV. The experiment was performed at the SPring-8/LEPS facility. The differential cross section of incoherent production shows a large suppression compared with the free proton case. The reduction for the deuteron cannot be clearly explained in terms of simple isospin asymmetry. The decay asymmetry of incoherent {phi} photo-production shows that the eta exchange process is small. Since the exclusive K{sup +}K{sup -}p cross section shows the same reduction with incoherent, both the proton and neutron cross section reduce similarly. Consequently, the {pi}-{eta} interference effect is small too. The present results suggest that our understanding of {phi} photo-production within a nucleus should be rearranged.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

A Search for deeply-bound Kaonic nuclear state at the J-PARC E15 experiment

The J-PARC E15 experiment will be performed to search for the simplest kaonic nuclear bound state, K-barNN, by the in-flight {sup 3}He(K{sup -},N) reaction. The exclusive measurement can be performed by a simultaneous measurement of the missing mass using the primary neutron or proton, and the invariant mass via the expected decay, e.g. K{sup -}pp{yields}{Lambda}p{yields}p{pi}{sup -}p. an overview of the experiment and the preparation status are reported.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Momentum dependence of the symmetry potential and its influence on nuclear reactions

A Skyrme-type momentum-dependent nucleon-nucleon force distinguishing isospin effect is parametrized and further implemented in the Lanzhou quantum molecular dynamics model, which leads to a splitting of nucleon effective mass in nuclear matter. Based on the isospin- and momentum-dependent transport model, we investigate the influence of momentum-dependent symmetry potential on several isospin-sensitive observables in heavy-ion collisions. It is found that symmetry potentials with and without the momentum dependence but corresponding to the same density dependence of the symmetry energy result in different distributions of the observables. The midrapidity neutron/proton ratios at high transverse momenta and the excitation functions of the total {pi}{sup -}/{pi}{sup +} and K{sup 0}/K{sup +} yields are particularly sensitive to the momentum dependence of the symmetry potential.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

K*{sup 0} production in Cu + Cu and Au + Au collisions at {radical}(s{sub NN})=62.4 GeV and 200 GeV

We report on K*{sup 0} production at midrapidity in Au + Au and Cu + Cu collisions at {radical}(s{sub NN})=62.4 and 200 GeV collected by the Solenoid Tracker at the Relativistic Heavy Ion Collider detector. The K*{sup 0} is reconstructed via the hadronic decays K*{sup 0}{yields}K{sup +}{pi}{sup -} and K*{sup 0}{yields}K{sup -}{pi}{sup +}. Transverse momentum, p{sub T}, spectra are measured over a range of p{sub T} extending from 0.2 GeV/c up to 5 GeV/c. The center-of-mass energy and system size dependence of the rapidity density, dN/dy, and the average transverse momentum, <p{sub T}>, are presented. The measured N(K*{sup 0})/N(K) and N({phi})/N(K*{sup 0}) ratios favor the dominance of rescattering of decay daughters of K*{sup 0} over the hadronic regeneration for the K*{sup 0} production. In the intermediate p{sub T} region (2.0<p{sub T}<4.0 GeV/c), the elliptic flow parameter, v{sub 2}, and the nuclear modification factor, R{sub CP}, agree with the expectations from the quark coalescence model of particle production.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

First observation of radiative B⁰ → ΦK⁰γ decays and measurements of their time-dependent CP violation

We report the first observation of the radiative decay B⁰→ ΦK⁰γ using a data sample of 772 × 10⁶ BB¯ pairs collected at the (4S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e⁻ collider. We observe a signal of 37 ± 8 events with a significance of 5.4 standard deviations including systematic uncertainties. The measured branching fraction is B(B⁰→ ΦK⁰γ) = (2.74±0.60±0.32)×10⁻⁶, where the uncertainties are statistical and systematic, respectively. We also report the first measurements of time-dependent CP-violation parameters: S ΦK⁰ S γ = +0.74 ⁺0.72 –1.05 (stat) +0.10 –0.24 (syst) and A ΦK⁰ S γ = +0.35 ± 0.58(stat) +0.23 –0.10 (syst). Furthermore, we measure B(B⁺ → ΦK⁺γ) = (2.48 ± 0.30 ± 0.24) × 10⁻⁶, ACP = –0.03 ± 0.11 ± 0.08 and find that the signal is concentrated in the M ΦK mass region near threshold.

Sahoo, Himansu B.↗
DOE OSTI2011

Analysis of the decay D{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}{pi}{sup 0}

We present the results of a Dalitz plot analysis of D{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}{pi}{sup 0} using the CLEO-c data set of 818 pb{sup -1} of e{sup +}e{sup -} collisions accumulated at {radical}(s)=3.77 GeV. This corresponds to 3x10{sup 6} D{sup 0}D{sup 0} pairs from which we select 1259 tagged candidates with a background of 7.5{+-}0.9 percent. Several models have been explored, all of which include the K{sup *}(892), K{sub 2}{sup *}(1430), K{sup *}(1680), the f{sub 0}(980), and the {sigma}(500). We find that the combined {pi}{sup 0{pi}0} S-wave contribution to our preferred fit is (28.9{+-}6.3{+-}3.1)% of the total decay rate while D{sup 0}{yields}K{sup *}(892){sup 0}{pi}{sup 0} contributes (65.6{+-}5.3{+-}2.5)%. Using three tag modes and correcting for quantum correlations we measure the D{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}{pi}{sup 0} branching fraction to be (1.058{+-}0.038{+-}0.073)%.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Search for CP Violation in {tau}{sup {+-}}{yields}K{sub S}{sup 0}{pi}{sup {+-}}{nu}{sub {tau}} Decays at Belle

We report on a search for CP violation in {tau}{sup {+-}}{yields}K{sub S}{sup 0}{pi}{sup {+-}}{nu}{sub {tau}} decays using a data sample of 699 fb{sup -1} collected by the Belle experiment at the KEKB electron-positron asymmetric-energy collider. The CP asymmetry is measured in four bins of the invariant mass of the K{sub S}{sup 0}{pi}{sup {+-}} system and found to be compatible with zero with a precision of O(10{sup -3}) in each mass bin. Limits for the CP violation parameter Im({eta}{sub S}) are given at the 90% confidence level. These limits are |Im({eta}{sub S})|<0.026 or better, depending on the parametrization used to describe the hadronic form factors, and improve upon previous limits by 1 order of magnitude.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Search for the e{sup +}e{sup -} {yields} K{sup {+-}}K{sub S}{pi}{sup Minus-Or-Plus-Sign} process on the VEPP-2M e{sup +}e{sup -} collider

We report on the results of the search for the e{sup +}e{sup -} {yields} K{sup {+-}}K{sub S}{pi}{sup Minus-Or-Plus-Sign} process. Data with an integrated luminosity of 1.36 pb{sup -1} collected in experiment with a spherical neutral detector (SND) on the VEPP-2M e{sup +}e{sup -} collider in the energy range from 1.36 to 1.38 GeV have been analyzed. The upper limits of the {sigma} < 150 pb cross sections of the sought process have been established for an energy of 1.37 GeV at a confidence level of 90%.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Dilepton and strangeness production probed with HADES

With the High Acceptance Di-Electron Spectrometer (HADES) at GSI we have studied dilepton production in the few-GeV energy regime in various collisions systems, from elementary NN, over pA, up to the medium-heavy Ar + KCl system. We have thus confirmed the puzzling results of the former DLS Collaboration at the Bevalac. While we have traced the origin of the excess pair yield in CC collisions to elementary pp and pn processes, in our Ar + KCl data a contribution from the dense phase of the collision has been identified. Together with the e{sup +}e{sup -} pairs, we have also obtained in the Ar + KCl system at 1.76 A GeV a high-statistics data set on open and hidden strangeness, i.e. K{sup {+-}}, K{sub s}{sup 0}, {Lambda}, {phi}, and {Xi}{sup -}, allowing for a comprehensive discussion of strangeness production in this system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Leptonic B Decays at BaBar

We will present the most recent results on leptonic B decays B{sup {+-}(0)} {yields} K*{sup {+-}(0)}{nu}{bar {nu}} and B{sup {+-}} {yields} {mu}{sup {+-}}{nu}, based on the data collected by the BaBar detector at PEP-II, an asymmetric e{sup +}e{sup -} collider at the center of mass energy of the {Upsilon}(4S) resonance. Rare B decays have always been a standard probe for New Physics (NP) searches. The very low Standard Model (SM) rate of these decays often make them unaccessible with the present experimental datasets, unless NP effects enhance the rate up to the current experimental sensitivity. Moreover, as NP effects can modify the decay kinematic, particular attention must be paid in order to perform a model independent analysis. A B-Factory provides an unique environment to investigate these processes. The high number of B{bar B} pairs produced by a B-Factory often allows to approach the needed experimental sensitivity. Moreover, the clean environment and the closed kinematic of the initial state enable to obtaining a very pure sample where to look for these decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Searches for New Physics in CP Violation from BABAR

Results of recent searches for new physics in CP violation in charm decays from the BABAR experiment are presented. These results include a measurement of D 0 - anti D 0 mixing and searches for CP violation in two-body D 0 decays, a search for CP violation in the charm decays D ± → K S 0 K ± and D s ± → K S 0 K ± , K S 0 π ± , and a search for direct CP violation in the singly-Cabibbo suppressed D ± → K + K - π ± decays. These studies are based on the final dataset collected by BABAR at the PEP-II B factory at SLAC in the period 1999-2008. No evidence of CP violation is found in these charm decays. The measured mixing parameter y CP = [0.72 ± 0.18(stat) ± 0.12(syst)]% excludes the no-mixing null hypothesis with a significance of 3.3σ .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The Structure of Excited 0{sup +} States in Nuclei and the Effect of the {gamma} Degree of Freedom

The physics of intrinsic states, within the pairing gap of deformed nuclei with N{approx}90 neutrons, is discussed in the light of the recent realization that the first excited 0{sub 2}{sup +} states in these nuclei are not {beta}-vibrations but four quasi-neutron states. The properties of {gamma}-vibration K{sup {pi}} = 2{sup +} bands is discussed. A method of measuring two proton transfer in high resolution using the ({sup 3}He,n) reaction is proposed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗