|
Xie, J. J., Liang, W. H., & Oset, E. (2016). (K)over-bar-induced formation of the f(0)(980) and a(0)(980) resonances on proton targets. Phys. Rev. C, 93(3), 035206–8pp.
Abstract: We perform a calculation of the cross section for nine reactions induced by (K) over bar scattering on protons. The reactions studied are K- p -> Lambda pi(+)pi(-), K- p -> Sigma(0)pi(+)pi(-), K- p -> Lambda pi(0)eta, K- p -> Sigma(0)pi(0)eta, K- p -> Sigma(+)pi(-)eta, (K) over bar (0) p -> Lambda pi(+)eta, (K) over bar (0) p -> Sigma(0)pi(+)eta, (K) over bar (0) p -> Sigma(+)pi(+)pi(-), and (K) over bar (0) p -> Sigma+pi(0)eta. We find that in the reactions producing pi(+)pi(-), a clear peak for the f(0)(980) resonance is found, while no trace of f(0)(500) appears. Similarly, in the cases of p. production, a strong peak is found for the a(0)(980) resonance, with the characteristic strong cusp shape. Cross sections and invariant mass distributions are evaluated which should serve, by comparing them with future data, to test the dynamics of the chiral unitary approach used for the evaluations and the nature of these resonances.
|
|
|
ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fernandez Martinez, P., et al. (2016). Search for magnetic monopoles and stable particles with high electric charges in 8 TeV pp collisions with the ATLAS detector. Phys. Rev. D, 93(5), 052009–25pp.
Abstract: A search for highly ionizing particles produced in proton-proton collisions at 8 TeV center-of-mass energy is performed by the ATLAS Collaboration at the CERN Large Hadron Collider. The data set used corresponds to an integrated luminosity of 7.0 fb(-1). A customized trigger significantly increases the sensitivity, permitting a search for such particles with charges and energies beyond what was previously accessible. No events were found in the signal region, leading to production cross section upper limits in the mass range 200-2500 GeV for magnetic monopoles with magnetic charge in the range 0.5g(D) < vertical bar g vertical bar < 2.0g(D), where g(D) is the Dirac charge, and for stable particles with electric charge in the range 10 < vertical bar z vertical bar < 60. Model-dependent limits are presented in given pair-production scenarios, and model-independent limits are presented in fiducial regions of particle energy and pseudorapidity.
|
|
|
Han, X. F., & Wang, L. (2016). Implication of the 750 GeV diphoton resonance on two-Higgs-doublet model and its extensions with Higgs field. Phys. Rev. D, 93(5), 055027–9pp.
Abstract: We examine the implication of the 750 GeV diphoton resonance on the two-Higgs-doublet model by imposing various theoretical and experimental constraints. The production rate of the two-Higgs-doublet model is smaller than the cross section observed at the LHC by 2 orders of magnitude. In order to accommodate the 750 GeV diphoton resonance, we extend the two-Higgs-doublet model by introducing additional Higgs fields, and focus on two different extensions: an inert complex Higgs triplet and a real scalar septuplet. As the 125 GeV Higgs is in agreement with the observed data, the production rate for the 750 GeV diphoton resonance can be enhanced to 0.6 fb for the former and 4.5 fb for the latter. The results of the latter are well consistent with the 750 GeV diphoton excess at the LHC.
|
|
|
T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., Izmaylov, A., Sorel, M., & Stamoulis, P. (2016). Measurement of the muon neutrino inclusive charged-current cross section in the energy range of 1-3 GeV with the T2K INGRID detector. Phys. Rev. D, 93(7), 072002–23pp.
Abstract: We report a measurement of the nu(mu)-nucleus inclusive charged-current cross section (= sigma(cc)) on iron using data from the INGRID detector exposed to the J-PARC neutrino beam. The detector consists of 14 modules in total, which are spread over a range of off-axis angles from 0 degrees to 1.1 degrees. The variation in the neutrino energy spectrum as a function of the off-axis angle, combined with event topology information, is used to calculate this cross section as a function of neutrino energy. The cross section is measured to be sigma(cc) (1.1 GeV) = 1.10 +/- 0.15 (10(-38) cm(2)/nucleon), sigma(cc) (2.0 GeV) = 2.07 +/- 0.27 (10(-38) cm(2)/nucleon), and sigma(cc) (3.3 GeV) = 2.29 +/- 0.45 (10(-38) cm(2)/nucleon), at energies of 1.1, 2.0, and 3.3 GeV, respectively. These results are consistent with the cross section calculated by the neutrino interaction generators currently used by T2K. More importantly, the method described here opens up a new way to determine the energy dependence of neutrino-nucleus cross sections.
|
|
|
IDS Collaboration(Lica, R. et al), & Morales, A. I. (2016). Fast-timing study of the l-forbidden 1/2(+) -> 3/2(+) M1 transition in Sn-129. Phys. Rev. C, 93(4), 044303–7pp.
Abstract: The levels in Sn-129 populated from the beta(-) decay of In-129 isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 1/2(+) state and the 3/2(+) ground state in 129Sn are expected to have configurations dominated by the neutron s(1/2) (l = 0) and d(3/2) (l = 2) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow l-forbidden M1 transition. Using fast-timing spectroscopy we havemeasured the half-life of the 1/2(+) 315.3-keV state, T-1/2 = 19(10) ps, which corresponds to a moderately fast M1 transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effective charges and g factors, predict a 4-ns half-life for this level. We can reconcile the shell-model calculations to the measured T-1/2 value by the renormalization of the M1 effective operator for neutron holes.
|
|
|
Di Valentino, E., Gariazzo, S., Gerbino, M., Giusarma, E., & Mena, O. (2016). Dark radiation and inflationary freedom after Planck 2015. Phys. Rev. D, 93(8), 083523–28pp.
Abstract: The simplest inflationary models predict a primordial power spectrum (PPS) of the curvature fluctuations that can be described by a power-law function that is nearly scale invariant. It has been shown, however, that the low-multipole spectrum of the cosmic microwave background anisotropies may hint at the presence of some features in the shape of the scalar PPS, which could deviate from its canonical power-law form. We study the possible degeneracies of this nonstandard PPS with the active neutrino masses, the effective number of relativistic species, and a sterile neutrino or a thermal axion mass. The limits on these additional parameters are less constraining in a model with a nonstandard PPS when including only the temperature autocorrelation spectrum measurements in the data analyses. The inclusion of the polarization spectra noticeably helps in reducing the degeneracies, leading to results that typically show no deviation from the Lambda CDM model with a standard power-law PPS. These findings are robust against changes in the function describing the noncanonical PPS. Albeit current cosmological measurements seem to prefer the simple power-law PPS description, the statistical significance to rule out other possible parametrizations is still very poor. Future cosmological measurements are crucial to improve the present PPS uncertainties.
|
|
|
Orrigo, S. E. A. et al, Rubio, B., Gelletly, W., Agramunt, J., Algora, A., & Molina, F. (2016). beta decay of the exotic T-z =-2 nuclei Fe-48, Ni-52, and Zn-56. Phys. Rev. C, 93(4), 044336–18pp.
Abstract: The results of a study of the beta decays of three proton-rich nuclei with T-z = -2, namely Fe-48, Ni-52, and Zn-56, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total beta-delayed proton emission branching ratios. We have measured the individual beta-delayed protons and beta-delayed. rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between beta-delayed protons and. rays is observed in the de-excitation of the T = 2 isobaric analog states in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case Zn-56, where the exotic beta-delayed gamma-proton decay has been observed.
|
|
|
AGATA Collaboration(Krzysiek, M. et al), & Gadea, A. (2016). Pygmy dipole resonance in Ce-140 via inelastic scattering of O-17. Phys. Rev. C, 93(4), 044330–8pp.
Abstract: The gamma decay from the high-lying states of Ce-140 excited via inelastic scattering of O-17 at a bombarding energy of 340 MeV was measured using the high-resolution AGATA-demonstrator array in coincidence with scattered ions detected in two segmented Delta E-E silicon detectors. Angular distributions of scattered ions and emitted gamma rays were measured, as well as their differential cross sections. The excitation of 1(-) states below the neutron separation energy is similar to the one obtained in reactions with the alpha isoscalar probe. The comparison between the experimental differential cross sections and the corresponding predictions using the distorted-wave Born approximation allowed us to extract the isoscalar component of identified 1(-) pygmy states. For this analysis the form factor obtained by folding microscopically calculated transition densities and optical potentials was used.
|
|
|
Sun, Z. F., & Vicente Vacas, M. J. (2016). Masses of doubly charmed baryons in the extended on-mass-shell renormalization scheme. Phys. Rev. D, 93(9), 094002–8pp.
Abstract: In this work, we investigate the mass corrections of the doubly charmed baryons up to (NLO)-L-2 in the extended-on-mass-shell (EOMS) renormalization scheme, comparing with the results of heavy baryon chiral perturbation theory. We find that the terms from the heavy baryon approach are a subset of those obtained in the EOMS scheme. By fitting the lattice data, we can determine the parameters (m) over tilde, alpha, c(1) and c(7) from the Lagrangian, while in the heavy baryon approach no information on c(1) can be obtained from the baryons mass. Correspondingly, the masses of m(Xi cc) and m(Omega cc) are predicted, in the EOMS scheme, extrapolating the results from different values of the charm quark and the pion masses of the lattice QCD calculations.
|
|
|
Wang, E., Chen, H. X., Geng, L. S., Li, D. M., & Oset, E. (2016). Hidden-charm pentaquark state in Lambda(0)(b) -> J/psi p pi(-) decay. Phys. Rev. D, 93(9), 094001–10pp.
Abstract: We study here the A(b)(0) -> J/psi p pi(-) reaction in analogy to the A(b)(0) -> J/psi pK(-) one, and we note that in both decays there is a sharp structure (dip or peak) in the J/psi p mass distribution around 4450 MeV, which is associated in the A(b)(0) -> J/psi pK(-) experiment to an exotic pentaquark baryonic state, although in J/psi p pi(-) it shows up with relatively low statistics. We analyze the A(b)(0) -> J/psi p pi(-) interaction along the same lines as the A(b)(0) -> J/psi pK(-) one, with the main difference stemming from the reduced Cabibbo strength in the former and the consideration of the pi(-)p final state interaction instead of the K(-)p one. We find that with a minimal input, introducing the pi(-)p and J/psi p interaction in S-wave with realistic interactions, and the empirical P-wave and D-wave contributions, one can accomplish a qualitative description of the pi(-)p and J/psi p mass distributions. More importantly, the peak structure followed by a dip of the experimental J/psi p mass distribution is reproduced with the same input as used to describe the data of A(b)(0) -> J/psi pK(-) reaction. The repercussion for the triangular singularity mechanism, invoked in some works to explain the pentaquark peak, is discussed.
|
|