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At least 91 records · Page 5

Natural GUT and the cosmology

In the natural GUT, not only realistic quark and lepton mass matrices can be obtained but also the most serious problem in the SUSY GUT, which is called the doublet-triplet splitting problem, can be solved under the natural assumption that all the interactions which are allowed by the symmetry are introduced with O(1) coefficients (including the higher dimensional operators). In this manuscript, we examine several cosmological aspects which are related with the natural GUT, B - L-genesis, non-thermal production of dark matter (DM), vacuum selection by particle production, and the inflation after the trapping. These works are based on several papers[1, 2, 3] collaborated with S. Enomoto, S. Iida, Y. Kurata, and T. Matsuda.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Precision spectroscopy of light kaonic atom X-rays in the SIDDHARTA experiment

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.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

An explicit SU(12) family and flavor unification model

An explicit SUSY SU(12) unification model with three light chiral families is presented which avoids any external flavor symmetries. The hierarchy of quark and lepton masses and mixings is explained by higher dimensional Yukawa interactions involving Higgs bosons containing SU(5) singlet fields with VEVs appearing at or below the SUSY GUT scale of 2 Multiplication-Sign 10{sup 16} GeV, approximately 50 times smaller than the SU(12) unification scale. The model has been found to be in good agreement with the observed quark and lepton masses and mixings, with nearly all prefactors of {beta}(1) in the four Dirac and one Majorana fermion mass matrices.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Theoretical study on the ground state of the polar alkali-metal-barium molecules: Potential energy curve and permanent dipole moment

In this paper, we systematically investigate the electronic structure for the {sup 2}Σ{sup +} ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Precision Spectroscopy of Kaonic Helium-3 X-rays at J-PARC

We will measure the x-rays from kaonic {sup 3}He and {sup 4}He 3d{yields}2p transition by using silicon drift detectors. Our precision goal is set to 1 eV to provide crucial information on the kaon-nucleus strong interaction in the low energy limit. The experiment is to be performed as one of the first experiment in the J-PARC hadron facility (J-PARC E17). An overview and the present status of the experiment are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Precision spectroscopy of kaonic {sup 3}He X-rays at J-PARC

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.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Weak decay rates for neutron-deficient Kr isotopes relevant for the rp process

Weak interaction rates under stellar density and temperature conditions relevant for the rp process are studied in neutron-deficient Kr isotopes. The nuclear structure part of the problem is described within the deformed Skyrme Hartree-Fock+BCS+QRPA, which reproduces not only the beta-decay half-lives but also the available Gamow-Teller strength distributions, measured under terrestrial conditions. The various sensitivities of the decay rates to both density and temperature are discussed. In particular, we study the contributions coming from excited states in the parent nucleus, which are thermally populated, and the competition between beta-decays and continuum electron captures.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Influence of nucleus potential on kaon and antikaon pairs decayed from short lived particles in a nucleus

We propose a possible way to probe the interactions of kaon- and antikaon-nucleus by measuring K{sup +}K{sup -} pairs decayed from {phi}(1020) meson in a nuclear target. The K{sup +}K{sup -} pairs emerged from nuclei can be affected by hadronic potentials and the difference of kaon- and antikaon-nucleus potential maybe modify invariant masses of K{sup +}K{sup -} decayed from {phi} mesons. The {phi} mesons can be produced with a lead target for the energy region 1.5{approx}2.4 GeV at LEPS facility in Super Photon Ring 8-GeV (Spring-8). By comparing results of Monte Carlo calculation with experimental data, we can probe kaon-, and antikaon-nucleus potential.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Charged nontopological soliton of the SU(2) Multiplication-Sign U(1) gauge model

The SU(2) Multiplication-Sign U(1) gauge model that is the bosonic sector of the Standard Model of electroweak interactions is considered. The existence of electrically charged nontopological solitons is shown to be possible in this model. Some properties of a charged nontopological soliton are investigated. Asymptotic expressions are derived for the soliton radius, energy, and phase frequency in the thin-wall regime by the method of trial functions. Numerical solutions of the model field equations corresponding to electrically charged non-topological solitions have been obtained. The dependences of the soliton energy and charge on phase frequency are given for several model parameters. It follows from the data obtained that there exists a domain of parameters in which a charged nontopological soliton is stable to the transition to a plane-wave field configuration.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Heavy Quark Hadrons and Exotics a challenge for QCD

Exotic hadrons with heavy quarks can confirm in the same multiquark system that the qq-bar interaction is much stronger than the qq interaction and produces color structures totally different from those of normal hadrons. Unusual heavy tetraquark structure may explain unusual properties of newly discovered mesons like the X(3872). Both charged and neutral B decays produce this narrow neutral resonant state that decays to both J/{psi}{rho} and J/{psi}{omega}, while no charged resonances in the same multiplet are found. This suggests that the X is an isoscalar resonance whose production conserves isospin, while isospin is violated only in the decay by an electromagnetic interaction allowing the isospin-forbidden J/{psi}{rho} decay. New data for X production in B decays provide a separation between production and decay, sharpen several experimental puzzles and impose serious constraints on all models. A proposed isoscalar tetraquark model agrees with all present data, conserves isospin in its production and breaks isospin only in an electromagnetic X(3872)J/{psi}{rho}{sup o} decay. The narrow X decay width results from the tiny phase space available for the J/{psi}{omega} decay and enables competition with the electromagnetic isospin-forbidden J/{psi}{rho} decay which has much larger phase space. Experimental tests are proposed for this isospin production invariance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Study of charge symmetry breaking in dd collisions with WASA-at-COSY

Charge symmetry is an approximate symmetry of the strong interaction. Studies of its breaking can yield information on the u and d quark mass difference. A theoretical collaboration is currently working on the description of charge symmetry breaking mechanisms for dd{yields}{alpha}{pi}{sup 0} and np{yields}d{pi}{sup 0} within Chiral Perturbation Theory, using the data from TRI-UMF and IUCF. One of the items in the program of the WASA-at-COSY collaboration is to extend the data base for the dd{yields}{alpha}{pi}{sup 0} reaction to higher energies, which would allow the extraction of the information on the p-wave. Status of the analysis of experimental data along with the preliminary results from the pilot run will be presented here.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Experimental studies on kaonic atoms at DA{Phi}NE

We have measured the K-series x-rays of kaonic hydrogen atoms to determine the strong-interaction energy-level shift and width of the 1s atomic state with significant improvements over the previous experiments. The measurement offers a unique possibility to precisely determine the complex K{sup -}p S-wave scattering length. We have also measured kaonic x-ray spectra with several gaseous targets : deuterium, helium-3 and helium-4. In this paper, we present an overview of this experiment and preliminary spectra of those kaonic x-rays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Vortices catapult droplets in atomization

A droplet ejection mechanism in planar two-phase mixing layers is examined. Any disturbance on the gas-liquid interface grows into a Kelvin-Helmholtz wave, and the wave crest forms a thin liquid film that flaps as the wave grows downstream. Increasing the gas speed, it is observed that the film breaks up into droplets which are eventually thrown into the gas stream at large angles. In a flow where most of the momentum is in the horizontal direction, it is surprising to observe these large ejection angles. Our experiments and simulations show that a recirculation region grows downstream of the wave and leads to vortex shedding similar to the wake of a backward-facing step. The ejection mechanism results from the interaction between the liquid film and the vortex shedding sequence: a recirculation zone appears in the wake of the wave and a liquid film emerges from the wave crest; the recirculation region detaches into a vortex and the gas flow over the wave momentarily reattaches due to the departure of the vortex; this reattached flow pushes the liquid film down; by now, a new recirculation vortex is being created in the wake of the wave—just where the liquid film is now located; the liquid film is blown up from below by the newly formed recirculation vortex in a manner similar to a bag-breakup event; the resulting droplets are catapulted by the recirculation vortex.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

On Wilson's theory of confinement

According to recent results, the Gell-Mann-Low function {beta}(g) of four-dimensional {phi}{sup 4} theory is nonalternating and has a linear asymptotics at infinity. According to the Bogoliubov and Shirkov classification, it means the possibility of constructing a continuous theory with finite interaction at large distances. This conclusion is in visible contradiction to the lattice results indicating triviality of {phi}{sup 4} theory. This contradiction is resolved by a special character of renormalizability in {phi}{sup 4} theory: to obtain the continuous renormalized theory, there is no need to eliminate a lattice from the bare theory. In fact, such kind of renormalizability is not accidental and can be understood in the framework of Wilson's many-parameter renormalization group. Application of these ideas to QCD shows that Wilson's theory of confinement is not purely illustrative, but has a direct relation to a real situation. As a result, the problem of analytical proof of confinement and a mass gap can be considered solved, at least on the physical level of rigor.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Toward a unified description of hadro- and photoproduction amplitudes

The near-term objectives of the research program at the Data Analysis Center are established within the context of the existing partial wave analyses available through the online suite of analysis and database codes accessible through SAID, the Scattering Analysis Interactive Database. This presentation reviews the efforts to determine a model independent method to obtain sets of partial wave amplitudes for strong and electromagnetic reactions, the interpretation of the amplitudes in terms of the excited states of the nucleon, the role of new precision unpolarized and polarized data, and new developments aimed at determining the photoproduction mulitpoles in a unitary, coupled-channel approach. The Chew-Mandelstam technique is discussed and applied to the problem of the S-wave pion- and eta-photoproduction amplitudes. The resulting eta production amplitudes exhibit the expected resonant behavior near the eta production threshold. Application of this method to a unified description of the hadro- and photoproduction amplitudes is discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Neutrino physics with dark matter experiments and the signature of new baryonic neutral currents

New neutrino states {nu}{sub b}, sterile under the standard model interactions, can be coupled to baryons via the isoscalar vector currents that are much stronger than the standard model weak interactions. If some fraction of solar neutrinos oscillate into {nu}{sub b} on their way to Earth, the coherently enhanced elastic {nu}{sub b}-nucleus scattering can generate a strong signal in the dark matter detectors. For the interaction strength a few hundred times stronger than the weak force, the elastic {nu}{sub b}-nucleus scattering via new baryonic currents may account for the existing anomalies in the direct detection dark matter experiments at low recoil. We point out that for solar-neutrino energies, the baryon-current-induced inelastic scattering is suppressed, so that the possible enhancement of a new force is not in conflict with signals at dedicated neutrino detectors. We check this explicitly by calculating the {nu}{sub b}-induced deuteron breakup, and the excitation of a 4.4 MeV {gamma} line in {sup 12}C. A stronger-than-weak force coupled to the baryonic current implies the existence of a new Abelian gauge group U(1){sub B} with a relatively light gauge boson.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗