116 results on '"*DECAY schemes (Radioactivity)"'
Search Results
2. New decay scheme of the 13651Sb85 6- isomer.
- Author
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Lozeva, R., Odahara, A., Moon, C.-B., Nishimura, S., Doornenbal, P., Naïdja, H., Nowacki, F., Soderström, P.-A., Sumikama, T., Lorusso, G., Wu, J., Xu, Z. Y., Baba, H., Browne, F., Daido, R., Daugas, J.-M., Didierjean, F., Fang, Y., Isobe, T., and Kojouharov, I.
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DECAY chains , *ISOMERS , *DECAY schemes (Radioactivity) , *NEUTRON-proton interactions , *ANGULAR momentum (Nuclear physics) - Abstract
We report new data on the 136Sb 6- yrast isomer with T1/2 = 489(40) ns and πg17/2 × νf37/2 configuration, populated in the projectile fission of 238U on a 9Be target. The analysis confirms the lifetime, providing a good accuracy measurement. In addition, the decay of the isomer to the ground state is newly suggested. Our result for the isomeric decay scheme is in a good agreement with shell-model calculations. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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3. Theoretical investigation of the decay of the N(2120) resonance to nucleon resonances near 1.7 GeV.
- Author
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Yin Huang, Jun He, Xu-Rong Chen, Rong Wang, Ju-Jun Xie, and Hong-Fei Zhang
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NUCLEAR particle research , *NUCLEAR vibrational states , *PIONS , *DECAY schemes (Radioactivity) , *COUPLING constants , *QUARK models - Abstract
Background: Until now the knowledge about nucleon resonances with a mass higher than 2 GeV has been scarce. Huge amounts of experimental data of the multipion photoproduction have been accumulated, and more can be expected in the future in facilities such as JLab 12 GeV. It makes it possible to investigate the decay of a nucléon resonance into another nucleon resonance. Purpose: The possibility to research the decay of the N(2120) to nucleon resonances near 1.7 GeV in the three-pion photoproduction will be explored to provide useful information for future experimental study. Method: The pion and radiative decay amplitudes of nucleon resonances are studied within the constituent quark model, which is used to calculate the couplings constants, especially for the decay of a nucleon resonance near 2.1 GeV to another nucleon resonance near 1.7 GeV. The three-pion photoproduction off the neutron target, i.e., γn n→ π-π- Δ++ → π-π-π+ p, is investigated based on the effective Lagrangian method with the coupling constant obtained form the decay amplitudes. Results: The resonance contribution with a state N(²PM)3/2 near 2.1 GeV decaying to a state N(4PM)5/2 near 1.7 GeV, i.e., N(2120) → N(1675)π, is dominant in the process considered. The total cross section from the resonance contribution is at the order of 1 μb and can be easily distinguished from the background. Conclusions: Our results suggest it is practicable to research the decay of the N(2120) to the N(1675) in experiment. [ABSTRACT FROM AUTHOR]
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- 2015
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4. Continuum excitations of 26O in a three-body model: 0+ and 2+ states.
- Author
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Grigorenko, L. V. and Zhukov, M. V.
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OXYGEN isotopes , *THREE-body problem , *EXCITED state energies , *FIELD theory (Physics) , *NUCLEAR cross sections , *DECAY schemes (Radioactivity) - Abstract
The structure and decay dynamics for 0+ and 2+ continuum excitations of 26O are investigated in a three-body 24O + n + n model. The validity of a simple approximation for the cross section profile for long-lived 2n emission is demonstrated. A sequence of three 0+ monopole ("breathing mode" type) excited states is predicted. These states could probably be interpreted as analogs of Efimov states pushed in the continuum due to insufficient binding. The calculated energies of the 2+ states are related to the excitation spectrum of 25O. We discuss the correlation between the predicted 26O spectrum and experimental observations. [ABSTRACT FROM AUTHOR]
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- 2015
- Full Text
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5. Consistent optical potential for incident and emitted low-energy α particles.
- Author
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Avrigeanu, V. and Avrigeanu, M.
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ALPHA particle scattering , *ZINC isotopes , *COULOMB barriers (Nuclear fusion) , *PROTONS , *DECAY schemes (Radioactivity) , *NUCLEAR reactions - Abstract
Recent measurements of α-particle induced reactions on the 64Zn nucleus, below and around the Coulomb barrier, are analyzed simultaneously with α-particle emission at similar energies in proton-induced reactions on Zn isotopes. All open reaction channels, particularly the γ decay, are calculated using consistent input parameters. Additionally, we check a previous optical-model potential for α particles on nuclei within the mass number range 45≤A≤209 [Avrigeanu et al., Phys. Rev. C 90, 044612 (2014)] and prove its correctness in the outgoing channel at least for the present case involving 64Zn and nearby nuclei. The reliability of this potential for incident as well as emitted low-energy α particles is supported by the successful reproduction of high-precision measured data, using no empirical rescaling factor of the γ and/or particle widths. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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6. Structure of the two-neutrino double-β decay matrix elements within perturbation theory.
- Author
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Štefánik, Dušan, Šimkovic, Fedor, and Faessler, Amand
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NEUTRINOS , *NUCLEAR matrix , *QUANTUM perturbations , *DECAY schemes (Radioactivity) , *GROUND state energy , *FERMI level , *PARTICLE symmetries - Abstract
The two-neutrino double-β Gamow-Teller and Fermi transitions are studied within an exactly solvable model, which allows a violation of both spin-isospin SU(4) and isospin SU(2) symmetries, and is expressed with generators of the SO(8) group. It is found that this model reproduces the main features of realistic calculation within the quasiparticle random-phase approximation with isospin symmetry restoration concerning the dependence of the two-neutrino double-β decay matrix elements on isovector and isoscalar particle-particle interactions. By using perturbation theory an explicit dependence of the two-neutrino double-β decay matrix elements on the like-nucleon pairing, particle-particle T=0 and T=1, and particle-hole proton-neutron interactions is obtained. It is found that double-β decay matrix elements do not depend on the mean field part of Hamiltonian and that they are governed by a weak violation of both SU(2) and SU(4) symmetries by the particle-particle interaction of Hamiltonian. It is pointed out that there is a dominance of two-neutrino double-β decay transition through a single state of intermediate nucleus. The energy position of this state relative to energies of initial and final ground states is given by a combination of strengths of residual interactions. Further, energy-weighted Fermi and Gamow-Teller sum rules connecting ΔZ=2 nuclei are discussed. It is proposed that these sum rules can be used to study the residual interactions of the nuclear Hamiltonian, which are relevant for charge-changing nuclear transitions. [ABSTRACT FROM AUTHOR]
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- 2015
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7. Phase-space factors and half-life predictions for Majoron-emitting β-β- decay.
- Author
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Kotila, J., Barea, J., and Iachello, F.
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NEUTRINO scattering , *MAJORONS , *PHASE space , *DECAY schemes (Radioactivity) , *WAVE functions , *NUCLEAR matrix , *COUPLING constants - Abstract
A complete calculation of phase space factors (PSFs) for Majoron-emitting 0νβ-β- decay modes is presented. The calculation makes use of exact Dirac wave functions with finite nuclear size and electron screening and includes lifetimes, single-electron spectra, summed electron spectra, and angular electron correlations. Combining these results with recent microscopic interacting boson model nuclear matrix elements (NMEs) we make half-life predictions for the ordinary Majoron decay (spectral index n=1). Furthermore, comparing theoretical predictions with the obtained experimental lower bounds for this decay mode we are able to set limits on the effective Majoron-neutrino coupling constant 〈gMee〉. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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8. Measurement of the Branching Fraction B(Λc+→pK-π+).
- Author
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Zupanc, A., Bartel, C., Gabyshev, N., Adachi, I., Aihara, H., Asner, D. M., Aulchenko, V., Aushev, T., Bakich, A. M., Bala, A., Belous, K., Bhuyan, B., Bondar, A., Bonvicini, G., Bozek, A., Bračko, M., Browder, T. E., Červenkov, D., Chang, M.-C., and Chekelian, V.
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BRANCHING ratios , *DECAY schemes (Radioactivity) , *ENERGY levels (Quantum mechanics) , *RADIOACTIVE decay , *NUCLEAR decay by heavy ion emission - Abstract
We present the first model-independent measurement of the absolute branching fraction of the Λ+c→pK-π+ decay using a data sample of 978 fb-1 collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The number of Λ+c baryons is determined by reconstructing the recoiling D(*)-̄pπ+ system in events of the type e+e-→D(*)−̄pπ+Λ+c. The branching fraction is measured to be B(Λ+c→pK-π+)=(6.84±0.24+0.21-0.27)%, where the first and second uncertainties are statistical and systematic, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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9. Spin and parity measurement of the Λ(1405) baryon.
- Author
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Moriya, K., Schumacher, R. A., Aghasyan, M., Amaryan, M. J., Anderson, M. D., Anefalos Pereira, S., Ball, J., Baltzell, N. A., Battaglieri, M., Bellis, M., Biselli, A. S., Bono, J., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., and Charles, G.
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BARYONS , *POLARIZATION (Nuclear physics) , *SHEAR waves , *DECAY schemes (Radioactivity) - Abstract
A determination of the spin and parity of the Λ(1405) is presented using photoproduction data from the CLAS detector at Jefferson Lab. The reaction γ+p→K++Λ(1405) is analyzed in the decay channel Λ(1405)→Σ++π-, where the decay distribution to Σ+π- and the variation of the Σ+ polarization with respect to the Λ(1405) polarization direction determines the parity. The Λ(1405) is produced, in the energy range 2.55
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- 2014
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10. Search for the Lepton-Flavor-Violating Decays Bs0→e±μ∓ and B0→e±μ∓.
- Author
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Aaij, R., Adeva, B., Adinolfi, M., Adrover, C., Affolder, A., Ajaltouni, Z., Albrecht, J., Alessio, F., Alexander, M., Ali, S., Alkhazov, G., Alvarez Cartelle, P., Alves, Jr., A. A., Amato, S., Amerio, S., Amhis, Y., Anderlini, L., Anderson, J., Andreassen, R., and Andrews, J. E.
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LEPTONS (Nuclear physics) , *PARTICLE decays , *DECAY schemes (Radioactivity) , *LUMINOSITY , *LEPTOQUARKS , *PARTICLES (Nuclear physics) - Abstract
A search for the lepton-flavor-violating decays B0s → e± μ± and B0 → e± μ± is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions at √s = 7 TeV, collected by the LHCb experiment. The observed number of B0s → e± μ± and B0 → e± μ± candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(B0s → e± μ±) < 1.1(1.4) x 10-8 and B(B0 → e± μ± ) <2.8(3.7) X 10-9 at 90% (95%) confidence level (C.L.). These limits are a factor of 20 lower than those set by previous experiments. Lower bounds on the Pati-Salam leptoquark masses are also calculated, MLQ(B0s → e± μ±)> 101 TeV/c2 and MLQ(B0s → e± μ±)> 126 TeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
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11. Propagation of nanofiber-guided light through an array of atoms.
- Author
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Kien, Fam Le and Rauschenbeute, A.
- Subjects
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CESIUM spectra , *LIGHT propagation , *NANOFIBERS , *BACKSCATTERING , *DECAY schemes (Radioactivity) , *HYPERFINE structure , *EXCITATION spectrum - Abstract
We study the propagation of nanofiber-guided light through an array of atomic cesium, taking into account the transitions between the hyperfine levels 6S1/2F = 4 and 6P3/2F' = 5 of the D2 line. We derive the coupled-mode propagation equation, the input-output equation, the scattering matrix, the transfer matrix, and the reflection and transmission coefficients for the guided field in the linear, quasistationary, weak-excitation regime. We show that, when the initial distribution of populations of atomic ground-state sublevels is independent of the magnetic quantum number, the quasilinear polarizations along the principal axes x and y, which are parallel and perpendicular, respectively, to the radial direction of the atomic position, are not coupled to each other in the linear coherent scattering process. When the guided probe field is quasilinearly polarized along the major principal axis x, forward and backward scattering have different characteristics. We find that, when the array period is far from the Bragg resonance, the backward scattering is weak. Under the Bragg resonance, most of the guided probe light can be reflected back in a broad region of field detunings even though there is an irreversible decay channel into radiation modes. When the atom number is large enough, two different band gaps may be formed, whose properties depend on the polarization of the guided probe field. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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12. Quantum statistics of four-wave mixing by a nonlinear resonant microcavity.
- Author
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Sherkunov, Y., Whittaker, David M., Schomerus, Henning, and Fal'ko, Vladimir
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FOUR-wave mixing , *QUANTUM statistics , *SPECTRUM analysis , *TWO-photon-spectroscopy , *DECAY schemes (Radioactivity) , *MULTIPHOTON processes , *OPTICAL resonance - Abstract
We analyze the correlation and spectral properties of two-photon states resonantly transmitted by a nonlinear optical microcavity. We trace the correlation properties of transmitted two-photon states to the decay spectrum of multiphoton resonances in the nonlinear microcavity. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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13. Dark photons and resonant monophoton signatures in Higgs boson decays at the LHC.
- Author
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Gabrielli, Emidio, Heikinheimo, Matti, Mele, Barbara, and Raidal, Martti
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PHOTONS , *HIGGS bosons , *DECAY schemes (Radioactivity) , *LARGE Hadron Collider , *STANDARD model (Nuclear physics) , *NUCLEAR magnetic resonance - Abstract
Motivated by dark-photon γ scenarios extensively considered in the literature, we explore experimentally allowed models where the Higgs boson coupling to photon and dark photon Hγγ can be enhanced. Correspondingly, large rates for the H ⇶ γγ decay become plausible, giving rise to one monochromatic photon with Eγ ≃ mH/2 (i.e., more than twice the photon energy in the rare standard-model decay H ⇶ γZ ⇶ γνν), and a similar amount of missing energy. We perform a model-independent study of this exotic resonant monophoton signature at the LHC, featuring a distinctive EγT peak around 60 GeV, and γ + ET transverse invariant mass ruled by mH. At parton level, we find a 5σ sensitivity of the present LHC data set for a H ⇶ γγ branching fraction of 0.5%. Such large branching fractions can be naturally obtained in dark U(1)F models explaining the origin and hierarchy of the standard model Yukawa couplings. We urge the LHC experiments to search for this new exotic resonance in the present data set and in future LHC runs. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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14. Closing in on the tip of the CMSSM stau coannihilation strip.
- Author
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Desai, Nishita, Ellis, John, Feng Luo, and Marrouche, Jad
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SUPERSYMMETRY , *LARGE Hadron Collider , *DARK matter , *STANDARD model (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
Near the tip of the τ coannihilation strip in the CMSSM with a neutralino lightest supersymmetric particle χ, the astrophysical cold dark matter density constraint forces the τ - χ mass difference to be small. If this mass difference is smaller than mτ, the τ may decay either in the outer part of an LHC detector--the "disappearing track" signature--or be sufficiently long-lived to leave the detector before decaying--the long-lived massive charged-particle signature. We combine searches for these signatures with conventional EmissT searches during LHC Run 1, identifying the small remaining parts of the CMSSM τ coannihilation strip region that have not yet been excluded and discussing how they may be explored during Run 2 of the LHC. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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15. Invisible Higgs decay width versus dark matter direct detection cross section in Higgs portal dark matter models.
- Author
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Seungwon Baek, Ko, P., and Wan-II Park
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HIGGS bosons , *DARK matter , *NUCLEAR cross sections , *FIELD theory (Physics) , *SCALAR mesons , *DECAY schemes (Radioactivity) - Abstract
The correlation between the invisible Higgs branching ratio (Binvh) versus dark matter (DM) direct detection cross section (σSIp) in Higgs portal singlet fermion DM (SFDM) or vector DM (VDM) models is usually presented in the effective field theory (EFT) framework. In this paper, we derive the explicit expressions for this correlation within UV completions of SFDM and VDM models with Higgs portals, and we discuss the limitations of the EFT approach. We show that there are at least two additional hidden parameters in sSIp in the UV completions: the singletlike scalar mass m2 and its mixing angle α with the SM Higgs boson (h). In particular, if the singletlike scalar is lighter than the SM Higgs boson (m2 < mhcosα/√1+cos²α), the collider bound becomes weaker than the one based on EFT. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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16. Search for an H-Dibaryon with a Mass near 2mΛ in ϒ(1S) and ϒ(2S) Decays.
- Author
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Kim, B. H., Olsen, S. L., Adachi, I., Aihara, H., Asner, D. M., Aulchenko, V., Bay, A., Belous, K., Bhuyan, B., Bonvicini, G., Bozek, A., Bračko, M., Browder, T. E., Chekelian, V., A. Chen, B. G. Cheon, Chilikin, K., histov, R. C, I.-S. Cho, and K. Cho
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DECAY schemes (Radioactivity) , *ENGINEERING instruments , *DIBARYON , *DEUTERON reactions , *EXOTIC baryons - Abstract
We report the results of a high-statistics search for H dibaryon production in inclusive ϒ(15) and Y(25) decays. No indication of an H dibaryon with a mass near the MH = 2mΛ threshold is seen in either the H → Λpπ- or ΛΛ decay channels and 90% confidence level branching-fraction upper limits are set that are between one and two orders of magnitude below the measured branching fractions for inclusive ϒ(1S) and ϒ(2S) decays to antideuterons. Since ϒ(1S, 2S) decays produce flavor-SU(3)-symmetric final states, these results put stringent constraints on H dibaryon properties. The results are based on analyses of 102 million ϒ(1S) and 158 million ϒ(2S) events collected with the Belle detector at the KEKB e+e- collider. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
17. Structure of 80Ge revealed by the ß decay of isomeric states in 80Ga: Triaxiality in the vicinity of 78Ni.
- Author
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Verney, D., Tastet, B., Kolos, K., Le Blanc, F., Ibrahim, F., Mhamed, M. Cheikh, Cottereau, E., Cuong, P. V., Didierjean, F., Duchêne, G., Essabaa, S., Ferraton, M., Franchoo, S., Khiem, L. H., Lau, C., Le Du, J.-F., Matea, I., Mouginot, B., Niikura, M., and Roussière, B.
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DECAY schemes (Radioactivity) , *GERMANIUM isotopes , *GALLIUM isotopes , *NUCLEAR structure , *NUCLEAR isomers , *NUCLEAR spin , *NICKEL isotopes - Abstract
The decays of two long-lived low-lying isomeric states of 80Ga were studied at the PARRNe mass separator of the ALTO ISOL facility. Over the 75 γ rays previously attributed to the 80Ga decay, the decay time of 67 individual β-delayed γ activities were measured. This allowed the determination of the decay time of these two recently reported long-lived--actually β-decaying--states as well as to partially disentangle the two decay schemes. Thanks to the relatively high spin difference between these two 80Ga isomers spin assignments of the daughter 80Ge states could be further constrained rendering the comparison with calculations easier. From this comparison it appears that the suspected maximum of collectivity at Z = 32 along the N = 50 line should express itself through the coexistence of spherical and collective β-soft structures. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
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18. Nuclear β+/EC decays in covariant density functional theory and the impact of isoscalar proton-neutron pairing.
- Author
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Niu, Z. M., Niu, Y. F., Liu, Q., Liang, H. Z., and Guo, J. Y.
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NEUTRON-proton interactions , *NUCLEAR electron capture , *DENSITY functional theory , *NONLINEAR analysis , *RELATIVITY (Physics) , *DECAY schemes (Radioactivity) , *NEUTRONS , *HEAVY nuclei , *QUASIPARTICLES , *SELF-consistent field theory - Abstract
Self-consistent proton-neutron quasiparticle random phase approximation based on the spherical nonlinear point-coupling relativistic Hartree-Bogoliubov theory is established and used to investigate the β+/electron-capture (EC)-decay half-lives of neutron-deficient Ar, Ca, Ti, Fe, Ni, Zn, Cd, and Sn isotopes. The isoscalar proton-neutron pairing is found to play an important role in reducing the decay half-lives, which is consistent with the same mechanism in the β decays of neutron-rich nuclei. The experimental β+/EC-decay half-lives can be well reproduced by a universal isoscalar proton-neutron pairing strength. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
19. Ultrafast formation and decay dynamics of trions in p-doped single-walled carbon nanotubes.
- Author
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Koyama, Takeshi, Shimizu, Satoru, Miyata, Yasumitsu, Shinohara, Hisanori, and Nakamura, Arao
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TRIONS (Nuclear physics) , *DECAY schemes (Radioactivity) , *CARBON nanotubes , *EXCITON theory , *PHOTOLUMINESCENCE - Abstract
We present the formation and decay dynamics of a trion (charged exciton) and exciton system in chemically p-doped single-walled carbon nanotubes (SWNTs) investigated by time-resolved photoluminescence measurements at 300 K. In (6,5) SWNTs with hole densities in the range of 0.27-1.05 nm-1, a trion is formed from the coalescence of an exciton and a free hole, with a rate of 1.7 × 1013 nm s-1. The linear dependence of the trion decay rate on the hole density allows us to find that the trion decay is governed by both a trion-hole Auger recombination process and an internal Auger recombination process. The observed high efficiencies of Auger processes dominate over the radiative recombination rate of trions, which demonstrates dynamic properties of excitonic complexes in the presence of enhanced Coulomb interactions in one-dimensional systems. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
20. Spin-dipole strength functions of 4He with realistic nuclear forces.
- Author
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Horiuchi, W. and Suzuki, Y.
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SPIN excitations , *DIPOLE moments , *NUCLEAR forces (Physics) , *HELIUM , *GROUND state energy , *DECAY schemes (Radioactivity) , *GAUSSIAN processes - Abstract
Both isoscalar and isovector spin-dipole excitations of 4He are studied using realistic nuclear forces in the complex scaling method. The ground state of 4He and discretized continuum states with Jπ=0-, 1-, 2- for A=4 nuclei are described in explicitly correlated Gaussians reinforced with global vectors for angular motion. Two- and three-body decay channels are specifically treated to take into account final state interactions. The observed resonance energies and widths of the negative-parity levels are all in fair agreement with those calculated from both the spin-dipole and electric-dipole strength functions as well as the energy eigenvalues of the complex scaled Hamiltonian. Spin-dipole sum rules, both non-energy-weighted and energy-weighted, are discussed in relation to tensor correlations in the ground state of 4He. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
21. Scalar Glueball in Radiative J/ψDecay on the Lattice.
- Author
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Long-Cheng Gui, Ying Chen, Gang Li, Chuan Liu, Yu-Bin Liu, Jian-Ping Ma, Yi-Bo Yang, and Jian-Bo Zhang
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RADIOACTIVE decay , *DECAY schemes (Radioactivity) , *GLUONS , *ANISOTROPY ,MESON decay - Abstract
The form factors in the radiative decay of J/ψ to a scalar glueball are studied within quenched lattice QCD on anisotropic lattices. The continuum extrapolation is carried out by using two different lattice spacings. With the results of these form factors, the partial width of J/ψ radiatively decaying into the pure gauge scalar glueball is predicted to be 0.35(8) keV, which corresponds to a branching ratio of 3.8(9) X 10-3. By comparing with experiments, out results indicate that f0 (1710) has a larger overlap with the pure gauge glueball than other related scalar mesons. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
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22. Reweighing the Evidence for a Light Higgs Boson in Dileptonic W Boson Decays.
- Author
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Barr, Alan J., Gripaios, Ben, and Lester, Christopher G.
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W bosons , *DECAY schemes (Radioactivity) , *BOSONS , *PARTICLES (Nuclear physics) , *INTERACTING boson models - Abstract
The article considers the transverse mass observable, originally used in the discovery of the W boson. It also defines an observable generalizing the transverse mass that takes into account the fact that one of the intermediate W bosons is likely to be on shell. A new variable is compared with existing ones and argues that it gives a significant improvement for discovery in the region mh 2mW.
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- 2012
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23. Determination of Weak Amplitudes Using Bose Symmetry and Dalitz Plots.
- Author
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Sinha, Rahul, Deshpande, N. G., Pakvasa, Sandip, and Sharma, Chandradew
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SCATTERING amplitude (Physics) , *BOSE-Einstein condensation , *DECAY schemes (Radioactivity) , *ISOBARIC spin , *NUCLEAR models - Abstract
We present a new method using Dalitz plots and Bose symmetry of pions that allows the complete determination of the magnitudes and phases of weak decay amplitudes. We apply the method to processes such as B → K* π, with the subsequent decay of K* → Kπ. Our approach enables the additional measurement of an isospin amplitude without any theoretical assumption. This advance will help in measuring the weak phase and probing for new physics beyond the standard model with fewer assumptions. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
24. Constraints and Tests of the OPERA Superluminal Neutrinos.
- Author
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Xiao-Jun Bi, Peng-Fei Yin, Zhao-Huan Yu, and Qiang Yuan
- Subjects
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SUPERLUMINAL radio sources (Astronomy) , *NEUTRINOS , *LORENTZ force , *DECAY schemes (Radioactivity) , *SPECTRUM analysis - Abstract
The superluminal neutrinos detected by OPERA indicate Lorentz invariance violation (LIV) of the neutrino sector at the order of 10-5. We study the implications of the result in this work. We find that such a large LIV implied by OPERA data will make the neutrino production process π → μ + vμ kinematically forbidden for a neutrino energy greater than about 5 GeV. The OPERA detection of neutrinos at 40 GeV can constrain the LIV parameter to be smaller than 3 x 10-7. Furthermore, the neutrino decay in the LIV framework will modify the neutrino spectrum greatly. The atmospheric neutrino spectrum measured by the IceCube Collaboration can constrain the LIV parameter to the level of 10-12. The future detection of astrophysical neutrinos of galactic sources is expected to be able to give an even stronger constraint on the LIV parameter of neutrinos. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
25. Search for Hadronic Decays of a Light Higgs Boson in the Radiative Decay Y → γA0.
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HADRON decay , *HIGGS bosons , *DECAY schemes (Radioactivity) , *MESONS , *BRANCHING ratios - Abstract
We search for hadronic decays of a light Higgs boson (A0) produced in radiative decays of an Y(2S) or Y(3S) meson, Y → γA0. The data have been recorded by the BABAR experiment at the Y(3S) and Y(2S) center-of-mass energies and include (121.3 ± 1.2) x 106 Y(3S) and (98.3 ± 0.9) x 106 Y(2S) mesons. No significant signal is observed. We set 90% confidence level upper limits on the product branching fractions B(Y(nS) → γA0)B(A0 → hadrons) (n = 2 or 3) that range from 1 x 10-6 for an A0 mass of 0.3 GeV/c⊃2 to 8 x 10-5 at 7 GeV/c⊃2. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
26. Observation of D+ → K+η(') and Search for CP Violation in D+ → π+η(') Decays.
- Author
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Won, E., Ko, B. R., Adachi, I., Aihara, H., Arinstein, K., Asner, D. M., Aushev, T., Bakich, A. M., Barberio, E., Bay, A., Bhardwaj, V., Bhuyan, B., Bischofberger, M., Bondar, A., Bozek, A., Bračko, M., Brodzicka, J., Browder, T. E., Chang, P., and Chen, A.
- Subjects
- *
DECAY schemes (Radioactivity) , *RADIOACTIVE decay , *DETECTORS , *MESONS , *COLLIDERS (Nuclear physics) - Abstract
We report the first observation of the doubly Cabibbo-suppressed decays D+ → K+ η(') using a 791 fb-1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The ratio of the branching fractions of doubly Cabibbo-suppressed relative to singly Cabibbo-suppressed D+ → π+η(') decays are B(D+ → K+η)/B(D+ → π+η) = (3.06 ± 0.43 ± 0.14)% and B(D+ → K+ η')/B(D+ → π+η') = (3.77 ± 0.39 + 0.10)%. From these, we find that the relative final-state phase difference between the tree and annihilation amplitudes in D+ decays, δTA, is (72 ± 9)° or (288 ± 9)°. We also report the most precise measurements of CP asymmetries to date: Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. (+ 1.74 ± 1.13 ± 0.19)% and Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. [ABSTRACT FROM AUTHOR]
- Published
- 2011
27. Decay of a metastable state induced by a spin bath.
- Author
-
Sinha, Sudarson Sekhar, Ghosh, Arnab, and Ray, Deb Shankar
- Subjects
- *
DECAY schemes (Radioactivity) , *QUANTUM theory , *DIFFUSION , *PHASE transitions , *PHASE equilibrium - Abstract
The spin-bath induced decay of a quantum system out of a metastable state, which can tunnel and undergo thermal activation, is considered. The treatment is based on the c-number description of bath degrees of freedom and a canonical thermal distribution of the associated c-number variables. We show that, apart from the usual frequency prefactor and its dynamical modification in the spatial diffusion-limited regime, i.e., the Grote-Hynes factor, the rate coefficient contains two other factors. One is a quantum correction to the dynamical factor resulting from quantum transmission and reflection of the particle at the finite barrier. This term exhibits exponential rate enhancement at low temperature. The other one is a quantum corrected Arrhenius factor, which incorporates the effect of thermal saturation. At 0 K, dissipation due to tunneling multiplies the tunneling probability by a factor that gets exponentially damped by friction, implying that, at this temperature, the behavior of spin bath is almost identical to that of a harmonic bath. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
28. Direct Observation of Two Protons in the Decay of 54Zn.
- Author
-
Ascher, P., Audirac, L., Adimi, N., Blank, B., Borcea, C., Brown, B. A., Companis, I., Delalee, F., Demonchy, C. E., de Oliveira Santos, F., Giovinazzo, J., Grévy, S., Grigorenko, L. V., Kurtukian-Nieto, T., Leblanc, S., Pedroza, J.-L., Perrot, L., Pibernat, J., Serani, L., and Srivastava, P. C.
- Subjects
- *
PROTONS , *ZINC isotopes , *DECAY schemes (Radioactivity) , *TIME projection chambers (Nuclear physics) , *HALF-life (Nuclear physics) , *NUCLEAR shell theory - Abstract
The two protons emitted in the decay of 54Zn have been individually observed for the first time in a time projection chamber. The total decay energy and the half-life measured in this work agree with the results obtained in a previous experiment. Angular and energy correlations between the two protons are determined and compared to theoretical distributions of a three-body model. Within the shell model framework, the relative decay probabilities show a strong contribution of the p2 configuration for the two- proton emission. After 45Fe, the present result on 54Zn constitutes only the second case of a direct observation of the ground state two-proton decay of a long-lived isotope. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
29. Influence of statistical sequential decay on isoscaling and symmetry energy coefficient in a GEMINI simulation.
- Author
-
Zhou, P., Tian, W. D., Ma, Y. G., Cai, X. Z., Fang, D. Q., and Wang, H. W.
- Subjects
- *
GEMINI (Constellation) , *HEAVY nuclei , *ATOMIC mass , *PARTICLES (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
Extensive calculations on isoscaling behavior with the sequential-decay model gemini are performed for the medium-to-heavy nuclei in the mass range A = 60-120 at excitation energies up to 3 MeV/nucleon. The comparison between the products after the first-step decay and the ones after the entire-steps decay demonstrates that there exists a strong sequential decay effect on the final isoscaling parameters and the apparent temperature. Results show that the apparent symmetry energy coefficient γapp does not reflect the initial symmetry energy coefficient Csym embedded in the mass calculation in the present GEMINI model. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
30. Auger recombination in Si and GaAs semiconductors: Ab initio results.
- Author
-
Govoni, Marco, Marri, Ivan, and Ossicini, Stefano
- Subjects
- *
AUGER electron spectroscopy , *SEMICONDUCTOR doping , *OPTOELECTRONICS , *OPTOELECTRONIC devices , *DECAY schemes (Radioactivity) , *RADIOACTIVE decay - Abstract
A detailed description, at the atomistic scale, of the dynamics of excess electrons and holes is fundamental in order to improve the performance of many optoelectronic devices. Among all recombination processes, nonradiative decay paths play a fundamental role in most semiconductor devices, such as optoelectronic devices and solar cells, limiting their efficiency. In this work, a precise ab initio analysis of the direct Auger recombination processes in both n- and p-type Si and GaAs crystals is presented. Our simulations of minority carrier Auger lifetimes rely on an accurate electronic band structure, calculated using density functional theory with the inclusion of quasiparticle corrections. The results obtained are in good agreement with experimental data for both n-Si and p-GaAs, proving the importance of the direct Auger recombination mechanism in such systems. On the contrary, we show that different nonradiative recombination paths are necessary to explain the experimental results for both p-Si and n-GaAs. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
31. Update rules and interevent time distributions: Slow ordering versus no ordering in the voter model.
- Author
-
Fernández-Gracia, J., Eguáluz, V. M., and San Miguel, M.
- Subjects
- *
DYNAMIC models , *THERMODYNAMICS , *BIOLOGICAL rhythms , *PROBABILITY theory , *DECAY schemes (Radioactivity) - Abstract
We introduce a general methodology of update rules accounting for arbitrary interevent time (IET) distributions in simulations of interacting agents. We consider in particular update rules that depend on the state of the agent, so that the update becomes part of the dynamical model. As an illustration we consider the voter model in fully connected, random, and scale-free networks with an activation probability inversely proportional to the time since the last action, where an action can be an update attempt (an exogenous update) or a change of state (an endogenous update). We find that in the thermodynamic limit, at variance with standard updates and the exogenous update, the system orders slowly for the endogenous update. The approach to the absorbing state is characterized by a power-law decay of the density of interfaces, observing that the mean time to reach the absorbing state might be not well defined. The IET distributions resulting from both update schemes show power-law tails. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
32. Nonmonotonic short-time decay of the Loschmidt echo in quasi-one-dimensional systems.
- Author
-
Goussev, Arseni
- Subjects
- *
STABILITY (Mechanics) , *QUANTUM perturbations , *AVOGADRO constant , *DECAY schemes (Radioactivity) , *MAXIMA & minima - Abstract
We study the short-time stability of quantum dynamics in quasi-one-dimensional systems with respect to small localized perturbations of the potential. To this end, we analytically and numerically address the decay of the Loschmidt echo (LE) during times that are short compared to the Ehrenfest time. We find that the LE is generally a nonmonotonic function of time and exhibits strongly pronounced minima and maxima at the instants when the corresponding classical particle traverses the perturbation region. We also show that, under general conditions, the envelope decay of the LE is well approximated by a Gaussian, and we derive explicit analytical formulas for the corresponding decay time. Finally, we demonstrate that the observed nonmonotonic nature of the LE decay is only pertinent to one-dimensional (and, more generally, quasi-one-dimensional) systems. and that the short-time decay of the LE can be monotonic in a higher number of dimensions. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
33. Decay study of 114Tc with a Penning trap.
- Author
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Rissanen, J., Kurpeta, J., Elomaa, V.-V., Eronen, T., Hakala, J., Jokinen, A., Moore, I. D., Karvonen, P., Plochocki, A., Próchniak, L., Penttilä, H., Rahaman, S., Reponen, M., Saastamoinen, A., Szerypo, J., Urban, W., Weber, C., and Äystö, J.
- Subjects
- *
DECAY schemes (Radioactivity) , *TECHNETIUM , *RUTHENIUM , *PENNING trap mass spectrometry , *SKYRME model - Abstract
The level structure of 114Ru has been investigated via the β decay of very neutron-rich 114Tc by means of Penning-trap-assisted γ spectroscopy. The deduced β-decay scheme suggests the existence of two β-decaying states in 114Tc with Iπ=1+ and I⩾ 4, with half-lives of t1/2(1+)=90(20) ms and t1/2(I⩾4)=100(20) ms, respectively. The Qβ value, which covers a possible mixture of two states, has been determined to be Qβ=11 785(12) keV. The level energies in 114Ru are compared with theory by using a microscopic Bohr Hamiltonian approach with the Sly4 version of the Skyrme interaction. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
34. 3.5 keV x-ray line from decaying gravitino dark matter.
- Author
-
Bomark, N.-E. and Roszkowski, L.
- Subjects
- *
GRAVITINO , *DARK matter , *X-ray astronomy , *DECAY schemes (Radioactivity) , *NEUTRINOS , *PHOTONS - Abstract
The article discusses a research that investigates the extremely weakly interacting similar to gravitino dark matter. Details about the identification of 3.5 keV x-ray line that can be generated in light gravitino decays to neutrinos and photons are noted. Also provided is the method of reheating temperature to avoid overproduction of gravitinos.
- Published
- 2014
- Full Text
- View/download PDF
35. Measurement of branching fractions and CP violation parameters in B → ωK decays with first evidence of CP violation in B0 → ωKs0.
- Author
-
Chobanova, V., Dalseno, J., Kiesling, C., Adachi, I., Aihara, H., Asner, D. M., Aulchenko, V., Aushev, T., Aziz, T., Bakich, A. M., Bala, A., Ban, Y., Belous, K., Bhuyan, B., Bobrov, A., Bonvicini, G., Bozek, A., BraÄko, M., Browder, T. E., and ÄŒervenkov, D.
- Subjects
- *
PARITY (Physics) , *PROPERTIES of nuclear particles , *DISCRETE symmetries , *BRANCHING ratios , *DECAY schemes (Radioactivity) , *CKM matrix - Abstract
We present a measurement of the branching fractions and charge-parity-(CP-)violating parameters in B → ωK decays. The results are obtained from the final data sample containing 772 x 106 BB̅ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We obtain the branching fractions B(B0 → ωK0) = (4.5 ± 0.4(stat) ± 0.3(syst)) × 10−6, B(B+ → ωK+) = (6.8 ± 0.4(stat) ± 0.4(syst)) x 10−6 which are in agreement with their respective current world averages. For the CP-violating parameters, we obtain AωKs0 = −0.36 ± 0.19(stat) ± 0.05(syst), SωKs0 = +0.91 ± 0.32(stat) ± 0.05(syst), A ωK+ = −0.03 ± 0.04(stat) ± 0.01 (syst), where A and S represent the direct and mixing-induced CP asymmetry, respectively. We find no evidence of CP violation in the decay channel B+ → ωK+; however, we obtain the first evidence of CP violation in the B0 → ωKs0 decay channel at the level of 3.1 standard deviations. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
36. Measurement of branching fractions and CP violation parameters in B → ωK decays with first evidence of CP violation in B0 → ωKs0.
- Author
-
Chobanova, V., Dalseno, J., Kiesling, C., Adachi, I., Aihara, H., Asner, D. M., Aulchenko, V., Aushev, T., Aziz, T., Bakich, A. M., Bala, A., Ban, Y., Belous, K., Bhuyan, B., Bobrov, A., Bonvicini, G., Bozek, A., BraÄko, M., Browder, T. E., and ÄŒervenkov, D.
- Subjects
- *
BRANCHING ratios , *DECAY schemes (Radioactivity) , *DETECTORS , *VERTEX detectors , *PHYSICS research - Abstract
We present a measurement of the branching fractions and charge-parity-(CP-)violating parameters in B → ωK decays. The results are obtained from the final data sample containing 772 x 106 BB̅ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We obtain the branching fractions B(B0 → ωK0) = (4.5 ± 0.4(stat) ± 0.3(syst)) × 10−6, B(B+ → ωK+) = (6.8 ± 0.4(stat) ± 0.4(syst)) x 10−6 which are in agreement with their respective current world averages. For the CP-violating parameters, we obtain AωKs0 = −0.36 ± 0.19(stat) ± 0.05(syst), SωKs0 = +0.91 ± 0.32(stat) ± 0.05(syst), A ωK+ = −0.03 ± 0.04(stat) ± 0.01 (syst), where A and S represent the direct and mixing-induced CP asymmetry, respectively. We find no evidence of CP violation in the decay channel B+ → ωK+; however, we obtain the first evidence of CP violation in the B0 → ωKs0 decay channel at the level of 3.1 standard deviations. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
37. CP asymmetries in three-body final states in charged D decays and CPT invariance.
- Author
-
Bediaga, I., Bigi, I. I., Miranda, J., and dos Reis, A. C.
- Subjects
- *
CPT theorem , *CP violation , *STANDARD model (Nuclear physics) , *DECAY schemes (Radioactivity) , *COMPUTER simulation , *CHIRAL perturbation theory - Abstract
The study of regional CP asymmetry in Dalitz plots of charm (& beauty) decays gives us more information about the underlying dynamics than the ratio between total rates. In this paper we explore the consequences of the constraint from CPT symmetry with emphasis on three-body D decays. We show simulations of D± → π±K+K- and discuss correlations with measured D± → π± π+ π-. There are important comments about analysis of recent LHCb data in CP asymmetries for B± decays to three-body final states. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
38. NLO corrections to χbJ to two-J/ψ exclusive decay processes.
- Author
-
Long-Bin Chen and Cong-Feng Qiao
- Subjects
- *
QUANTUM chromodynamics , *DECAY schemes (Radioactivity) , *LARGE Hadron Collider , *P-waves (Seismology) , *QUARKONIUMS , *BRANCHING ratios , *CHARMONIUM - Abstract
The next-to-leading order QCD corrections for χbJ, the p-wave bottomonium, to J/ψ pair decay processes are evaluated utilizing NRQCD factorization formalism. The scale dependence of the χb2 →J/ψJ/ψ process is depressed with NLO corrections, and hence the uncertainties in the leading-order results are greatly reduced. The total branch ratios are found to be the order of 10-5 for all three χbJ→J/ψJ/ψ processes, indicating that they are observable in the LHC and SuperB experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
39. γ*N → N(1710) transition at high momentum transfer.
- Author
-
Ramalho, G. and Tsushima, K.
- Subjects
- *
MOMENTUM transfer , *QUARKS , *HELICITY of nuclear particles , *RESONANCE , *DECAY schemes (Radioactivity) - Abstract
In a relativistic quark model we study the structure of the N(1710) resonance, and the γ*N → N(1710) reaction focusing on the high momentum transfer region, where the valence quark degrees of freedom are expected to be dominant. The N(1710) resonance, a state with spin 1/2 and positive parity (JP = 1/2+), can possibly be interpreted as the second radial excitation of the nucleon, after the Roper, N(1440). We calculate the γ*N → N(1710) helicity amplitudes, and predict that they are almost identical to those of the γ*N → N(1440) reaction in the high momentum transfer region. Thus, future measurement of the helicity amplitudes for the γ*N → N(1710) reaction can give a significant hint on the internal structure of the N(1710) state. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
40. Bounding the top Yukawa coupling with Higgs-associated single-top production.
- Author
-
Englert, Christoph and Re, Emanuele
- Subjects
- *
YUKAWA interactions , *STANDARD model (Nuclear physics) , *FERMIONS , *LARGE Hadron Collider , *COUPLING constants , *DECAY schemes (Radioactivity) , *HIGGS bosons - Abstract
After the discovery of the 125 GeV scalar boson with gauge properties similar to the Standard Model (SM) Higgs, the search for beyond the SM interactions will focus on studying the discovered particles' coupling properties more precisely and shedding light on the relation of fermion masses with the electroweak vacuum. The large mass of the top quark and the SM-predicted order one top Yukawa coupling is a natural candidate for beyond the SM physics, though experimentally challenging to constrain. In this paper, we argue that investigating angular correlations in pp → τHj production provides an excellent handle to constrain the top Yukawa coupling yt, via direct measurements, even when we focus on rare exclusive final states. We perform a hadron-level analysis and show that we may expect to constrain yt, ≳ 0.5ytSM at 95%-99% confidence level at the high luminosity LHC using semileptonic top decays and H → γγ alone, by employing a two-channel measurement approach. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
41. Heavy neutrino searches at the LHC with displaced vertices.
- Author
-
Helo, J. C., Kovalenko, S. G., and Hirsch, M.
- Subjects
- *
NEUTRINOS , *STANDARD model (Nuclear physics) , *VERTEX detectors , *LARGE Hadron Collider , *LEPTONS (Nuclear physics) , *DECAY schemes (Radioactivity) - Abstract
Sterile neutrinos with masses in the range of 1-100 GeV have been searched for in a variety of experiments. Here, we discuss the prospects of searching for sterile neutrinos at the LHC using displaced vertices. Two different cases are discussed: (i) the standard model extended with sterile neutrinos, and (ii) right-handed neutrinos in a left-right symmetric extension of the standard model. A dedicated displaced vertex search will allow us to probe parts of the parameter space not accessible to other searches, but both cases will require a large luminosity. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
42. Updated cross section measurement of e+e- → K+K-J/ψ and KS0KS0J/ψ via initial state radiation at Belle.
- Author
-
Shen, C. P., Yuan, C. Z., Wang, P., Abdesselam, A., Adachi, I., Aihara, H., Al Said, S., Asner, D. M., Aulchenko, V., Aushev, T., Ayad, R., Bakich, A. M., Bala, A., Bobrov, A., Bonvicini, G., Bozek, A., Bracko, M., Browder, T. E., Chekelian, V., and Chen, A.
- Subjects
- *
NUCLEAR cross sections , *CENTER of mass , *DECAY schemes (Radioactivity) , *RESONANCE , *PARTICLES (Nuclear physics) - Abstract
The cross sections of the processes e+e- → K+K-J/ψ and KS0KS0J/ψ are measured via initial state radiation at center-of-mass energies between the threshold and 6.0 GeV using a data sample of 980 fb-1 collected with the Belle detector on or near the Υ(nS) resonances, where n=1,2,...,5. The cross sections for e+e-→K+K-J/ψ are at a few pb level and the average cross section for e+e- → KS0KS0J/ψ is 1.8 ± 0.6(stat) ± 0.3(syst) pb between 4.4 and 5.2 GeV. All of them are consistent with previously published results with improved precision. A search for resonant structures and associated intermediate states in the cross section of the process e+e-K+K-J/ψ is performed. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
43. Study of B0 → ρ0ρ0 decays, implications for the CKM angle ɸ2 and search for other B0 decay modes with a four-pion final state.
- Author
-
Vanhoefer, P., Dalseno, J., Kiesling, C., Adachi, I., Aihara, H., Asner, D. M., Aulchenko, V., Aushev, T., Bakich, A. M., Bala, A., Bhardwaj, V., Bhuyan, B., Bonvicini, G., Bozek, A., Bračko, M., Browder, T. E., Chang, M.-C., Chang, P., Chekelian, V., and Chen, A.
- Subjects
- *
BRANCHING ratios , *CKM matrix , *POLARIZATION (Nuclear physics) , *DECAY schemes (Radioactivity) , *ISOBARIC spin , *MESONS , *STANDARD deviations , *MAGNETIC spectrometer - Abstract
We present a study of the branching fraction of the decay B0 → ρ0ρ0 and the fraction of longitudinally polarized ρ0 mesons in this decay. The results are obtained from the final data sample containing 772 × 106 BB pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find 166±59 B0 → ρ0ρ0 events (including systematic uncertainties), corresponding to a branching fraction of B(B0 → ρ0ρ0) = (1.02±0.30(stat) ± 0.15(syst)) × 10-6 with a significance of 3.4 standard deviations and a longitudinal polarization fraction fL = 0.21+0.18-0.22(stat)±0.15(syst). We use the longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa matrix angle ɸ2 = (84.9±13.5)° through an isospin analysis in the B → ρρ system. We furthermore find 125±41 B0 → f0ρ0 events, corresponding to B(B0 → f0ρ0) × B(f0 → π+π-) = (0.78±0.22(stat)±0.11(syst)) × 10-6, with a significance of 3.1 standard deviations. We find no other significant contribution with the same final state, and set upper limits at 90% confidence level on the (product) branching fractions, B(B0 → π+π-π+π-) < 11.2 × 10-6, B(B0 → ρ0π+π-) < 12.0 × 10-6, B(B0 → f0π+π-)×B(f0 → π+π-) < 3.0 × 10-6 and B(B0 → f0f0)×B(f0 → π+π-)² < 0.2×10-6. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
44. Precision v̅e-electron scattering measurements with IsoDAR to search for new physics.
- Author
-
Conrad, J. M., Shaevitz, M. H., Shimizu, I., Spitz, J., Toups, M., and Winslow, L.
- Subjects
- *
ELECTRON scattering , *DECAY schemes (Radioactivity) , *PARTICLES (Nuclear physics) , *LIQUID scintillators , *LITHIUM - Abstract
IsoDAR provides a pure and intense v̅e source with an average energy of 6.5 MeV produced through 8Li β decay. This source can be paired with a large scintillator detector, such as KamLAND, to produce a sample of v̅e-electron scatters that is more than 5 times larger than what has been collected before. Such a sample would allow for a 3.2% measurement of sin2θW and a sensitive search for nonstandard interactions. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
45. Light sterile neutrino sensitivity at the nuSTORM facility.
- Author
-
Adey, D., Agarwalla, S. K., Ankenbrandt, C. M., Asfandiyarov, R., Back, J. J., Barker, G., Baussan, E., Bayes, R., Bhadra, S., Blackmore, V., Blondel, A., Bogacz, S. A., Booth, C., Boyd, S. B., Bramsiepe, S. G., Bravar, A., Brice, S. J., Bross, A. D., Cadoux, F., and Cease, H.
- Subjects
- *
MUONIC neutrino , *DECAY schemes (Radioactivity) , *NEUTRINO oscillation , *METAPHYSICAL cosmology , *HELIUM , *LIQUID scintillators , *NEUTRINO detectors - Abstract
A facility that can deliver beams of electron and muon neutrinos from the decay of a stored muon beam has the potential to unambiguously resolve the issue of the evidence for light sterile neutrinos that arises in short-baseline neutrino oscillation experiments and from estimates of the effective number of neutrino flavors from fits to cosmological data. In this paper, we show that the nuSTORM facility, with stored muons of 3.8 GeV/c ± 10%, will be able to carry out a conclusive muon neutrino appearance search for sterile neutrinos and test the LSND and MiniBooNE experimental signals with 10s sensitivity, even assuming conservative estimates for the systematic uncertainties. This experiment would add greatly to our knowledge of the contribution of light sterile neutrinos to the number of effective neutrino flavors from the abundance of primordial helium production and from constraints on neutrino energy density from the cosmic microwave background. The appearance search is complemented by a simultaneous muon neutrino disappearance analysis that will facilitate tests of various sterile neutrino models. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
46. Search for the rare decays J/ψ → Ds−ρ+ and J/ψ → D̅0K̅*0.
- Author
-
Ablikim, M., Achasov, M. N., Ai, X. C., Albayrak, O., Albrecht, M., Ambrose, D. J., An, F. F., An, Q., Bai, J. Z., Ferroli, R. Baldini, Ban, Y., Bennett, J. V., Bertani, M., Bian, J. M., Boger, E., Bondarenko, O., Boyko, I., Braun, S., Briere, R. A., and Cai, H.
- Subjects
- *
BRANCHING ratios , *SPECTROMETERS , *DECAY schemes (Radioactivity) , *OBSERVED confidence levels (Statistics) - Abstract
A search for the rare decays of J/ψ → Ds−ρ+ + c.c. and J/ψ → D̅0K̅*0 + c.c. is performed with a data sample of 225.3-million J/ψ events collected with the Beijing Spectrometer III detector. No evident signal is observed. Upper limits on the branching fractions are determined to be B(J/ψ → Ds−ρ+ + c.c.) < 1.3 × 10−5 and B(J/ψ → D̅0K̅*0 + c.c.) < 2.5 × 10-6 at the 90% confidence level. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
47. Decay time of hollow argon atoms formed below metal and dielectric surfaces.
- Author
-
Briand, J. P., Phaneuf, R., Aryal, N. B., Baral, K. K., Thomas, C. M., and Esteves, D. A.
- Subjects
- *
ARGON , *DIELECTRIC materials , *CYCLOTRON resonance , *DECAY schemes (Radioactivity) , *KINETIC energy , *METALLIC surfaces , *X-rays - Abstract
Slow highly charged ions penetrating surfaces quickly capture many electrons in highly excited states, leaving empty the innermost shells, forming hollow atoms. These hollow atoms then fill their innermost shells in a stepwise manner through a long cascade of Auger and x-ray transitions. We have measured the mean emission depths of the series of x rays emitted during the decay cascade of Ar hollow atoms formed below the surface of metal and dielectric materials. It has been found that the decay times of these hollow atoms are much longer in dielectrics than in metals, and at keV/q kinetic energies, at depths of the order of 10-20 nm, considerably deeper than any expected value. These findings have been tentatively explained by the different responses of metals and dielectrics to the slow penetration of a highly charged ion. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
48. Study of J/ψ → ωpp at BESIII.
- Subjects
- *
ATOMIC mass , *BRANCHING ratios , *PHYSICAL measurements , *INVARIANTS (Mathematics) , *DECAY schemes (Radioactivity) , *NUCLEAR physics - Abstract
The decay J/ψ →ωpp has been studied, using 225.3 X 106 J/ψ events accumulated at BESIH. No significant enhancement near the pp invariant-mass threshold [denoted as X(pp)] is observed. The upper limit of the branching fraction B ( J / ψ → ωX(pp) → ωpp) is determined to be 3.9 X 10-6 at the 95% confidence level. The branching fraction of J / ψ →ωpp is measured to be B ( J / ψ → ωpp) = (9.0 ± 0.2(stat) ± 0.9(syst)) x 10-4. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
49. Measurement of η' → π+π-e+e- and η' → π+π-μ+μ-.
- Subjects
- *
NUCLEAR counters , *MASS spectrometry , *RADIOACTIVE decay , *BRANCHING ratios , *PREDICTION models , *DECAY schemes (Radioactivity) - Abstract
Based on a sample of 225.3 million J/Ψ events accumulated with the BESIII detector at the BEPCII, the decays of η' → π+π-l+l- are studied via J/Ψ → γη'. A clear η' signal is observed in the π+π-e+e- mass spectrum, and the branching fraction is measured to be B(η' → π+π-e+e-) = (2.11 ± 0.12(stat) ± 0.14(syst)) X 10-3, which is in good agreement with theoretical predictions and the previous measurement, but is determined with much higher precision. No η' signal is found in the π+π-μ+μ-mass spectrum, and the upper limit is determined to be B(η' → π+π-μ+μ- < 2.9 X 10-5 at the 90% confidence level. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
50. Partial wave analysis of J/Ψ → γηη.
- Subjects
- *
WAVE analysis , *BRANCHING ratios , *NUCLEAR counters , *RELATIVISTIC energy , *RESONANCE , *DECAY schemes (Radioactivity) - Abstract
Based on a sample of 2.25 X 108 J/Ψ events collected with the BESIII detector at BEPCII, a full partial wave analysis on J/Ψ → γηη was performed using the relativistic covariant tensor amplitude method. The results show that the dominant 0++ and 2++ components are from the f0(1710), f0(2100), f0(1500), f'2(1525), f2(1810) and f2(2340). The resonance parameters and branching fractions are also presented. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
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