Quark mass effects as isospin and SU(3) violations in radiative decays of vector mesons

Radiative decays of vector mesons, V → Pγ, are discussed in terms of the QCD quark model, in the chiral limit. By taking into account isospin and SU(3) breaking by the quark mass matrix good agreement is found with the experimental data. In particular, the hitherto unexplained smallness of the K¹⁰ → K⁰γ and ?^? → π^?γ rates is justified provided $\text{m}{}_{\mathrm{<mtext>s</mtext>}}\text{m}{}_{\mathrm{<mtext>d</mtext>}}\text{≈ 20}$ and $\text{m}{}_{\mathrm{<mtext>d</mtext>}}\text{m}{}_{\mathrm{<mtext>u</mtext>}}\text{? 50}$.     

Microwave optical double resonance and continuous wave dye laser excitation spectroscopy of NO2: Rotational assignment of the K = 0−4 subbands of the 593 nm band

A rotational assignment of approximately 80 lines with K_a′ = 0, 1, 2, 3, and 4 has been made of the 593 nm ${}^2\text{A}{}_1\text{→}{}^2\text{B}{}_2$ band of NO₂ using cw dye laser excitation and microwave optical double-resonance spectroscopy. Rotational constants for the ²B₂ state were obtained as A = 8.52 cm^?1, B = 0.458 cm^?1, and C = 0.388 cm^?1. Spin splittings for the K_a′ = 0 excited state levels fit a simple symmetric top formula and give $\text{(?}{}_{\mathrm{bb}}\text{+ ?}{}_{\mathrm{cc}}\text{)}\text{2}\text{= ?0.0483}\text{cm}{}^{\mathrm{?1}}$. Spin splittings for K_a′ = 1 (N′ even) are irregular and are shown to change sign between N′ = 6 and 8. Assuming that the large inertial defect of 4.66 amu Ų arises solely from A, a structure for the ²B₂ state is obtained which gives $\text{r}\text{(NO) = 1.35}\text{A}\text{?}$ and an ONO angle of 105°. Alternatively, weighting the three rotational constants equally gives $\text{r = 1.29}\text{A}\text{?}$ and θ = 118°.     

Does the enhancement mechanism work in non-leptonic decays of heavy pseudoscalar mesons with new flavors (b and t)?

We show that the enhancement mechanism proposed for non-leptonic decays of charmed mesons (D⁰, F⁺) is still important for decays of pseudoscalar mesons with b flavor, while its effect is small for mesons with t flavor. For the semi-leptonic branching ratios of B^? (b$\text{u}$), B⁰(b$\text{d}$) and B_S⁰(b$\text{s}$) we predict BR (B^? → evX ～' 9%, BR(B⁰ → evX) ～' BR(B_s⁰ → evX) ～' 5%. We can also derive the enhancement of the branching ratios of uncharmed final states in B decays, i.e. $\text{BR}\text{(}\text{B}{}^{\mathrm{?}}\text{→}\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>u</mtext>}}\text{)}$ ～' 20 %, $\text{BR}\text{(}\text{B}{}^0\text{→}\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>d</mtext>}}\text{)}$ ≈ 10%, where $\text{X}{}_{\mathrm{<mtext>s</mtext><mtext>u</mtext><mtext>(</mtext><mtext>s</mtext><mtext>d</mtext><mtext>)</mtext>}}$ = $\text{K}$π + ... + $\text{K}$K$\text{K}$ + ... .     

O(18) revived: Splitting the spinor

We propose an O(18) theory which is perturbatively unifiable and which accounts for the absence of right-handed families in the low-energy world. The theory predicts a fourth left-handed family as well as four right-handed families at energies near the weak scale. It also implies the existence of eight light neutrinos, all of which contribute to the width of the Z⁰. Cosmological arguments suggest that four of these neutrinos should have masses between 2 and 35 GeV, and that the other four should be much lighter. They also suggest the existence of a doubly charged scalar φ⁺⁺ and a singly charged scalar φ⁺. Dramatic signatures include the production of four right-handed charged leptons and eight right-handed quarks, $\text{Z}{}^0\text{→ v′}{}_{\mathrm{<mtext>R</mtext>}}\text{+}\text{v}\text{′}{}_{\mathrm{<mtext>R</mtext>}}\text{→ v}{}_{\mathrm{<mtext>R</mtext>}}\text{γ +\_}\text{v}{}_{\mathrm{<mtext>R</mtext>}}\text{γ}$, and e⁺e^? → φ⁺⁺ + φ^??. The lightest right-handed charged quark should be surprinsingly long-lived $\text{(τ?10}{}^{\mathrm{?2}}\text{sec}\text{)}$ for a particle of mass ? 100 GeV.     

Momentum transfer distributions of some diffractive enhancements in K−p interactions at 14.3 GeV/c

We discuss the structure of the momentum transfer distributions for the diffractive dissociation processes p → nπ⁺, p → Δ⁺⁺π^? and $\text{K}{}^{\mathrm{?}}\text{→}\text{K}{}_{890}{}^{10}\text{π}{}^{\mathrm{?}}$. In the near-threshold mass region a clear break of slope is found around t′KK ～ 0.25 GeV² for the two baryonic channels, whereas no comparable structure is seen for the mesonic system. The $\text{K}\text{→}\text{K}{}^1\text{π}$ differential cross section exhibits a nearly exponential behaviour up to t′_pp ～ 0.6 GeV², falling over three orders of magnitude. The slope variations and breaks are strongly correlated both to the mass region considered and to the decay angle of the fragmentation system.     

The Hilbert-Schmidt method in the three-particle problem and determination of the vertex parts tdn and td1n

Vertex constants for virtual decays $\text{t→d+n}\text{and}\text{t→d}{}^1\text{+n}$ are calculated using the resonance expansion technique for the three-particle amplitude suggested recently in ref. [1]. In the model with a spin-dependent separable NN-potential values $\text{G}{}_{\mathrm{<mtext>tdn</mtext>}}{}^2\text{=1.92}\text{fm}\text{, G}{}_{\mathrm{<mtext>td1n</mtext>}}{}^2\text{=?0.38}\text{fm}$ are obtained.     

Two-body density matrix of bose fluids

A detailed cluster analysis of the two-body density matrix $\text{n(}\text{r}{}_1\text{,}\text{r}{}_2\text{,}\text{r}\text{′}{}_1\text{,}\text{r}\text{′}{}_2\text{)}$ and the associated pairing matrix elements is performed for a strongly interacting system of bosons described by a Jastrow wave function. The study employs a multiplicative cluster procedure as suggested by Feenberg. It is demonstrated that the density matrix has a structure $\text{f(r)f(r′)n(r)n(r′)}\text{exp}\text{[?R(}\text{r}{}_1\text{,}\text{r}{}_2\text{,}\text{r}\text{′}{}_1\text{,}\text{r}\text{′}{}_2\text{)]}$ where f(r) is the conventional Jastrow factor and n(r) the one-body density matrix corresponding to the Jastrow trial state $\text{(r  |}\text{r}{}_1\text{?}\text{r}{}_2\text{|, r′  |}\text{r}\text{′}{}_1\text{?}\text{r}\text{′}{}_2\text{|)}$. The function R may be expressed by a series of irreducible cluster contributions which are given by a compact expressions in terms of spatial distribution functions. The density matrix exhibits off-diagonal long range order of the type $\text{n(}\text{r}{}_1\text{,}\text{r}{}_2\text{,}\text{r}\text{′}{}_1\text{,}\text{r}\text{′}{}_2\text{) → f(r)n(r)f(r′)n(r′)}\text{as}\text{|}\text{r}{}_1\text{?}\text{r}\text{′}{}_1\text{| → ∞,r,r′ < ∞}$. The associated pairing matrix elements and pairing energy of a Bose fluid are derived upon proper specialization of our results for the two-body density matrix.     

Neutral pion production by weak neutral currents in neutrino and antineutrino reactions

A study is presented of single π^o production in neutrino and antineutrino interactions in Gargamelle filled with freon CF₃Br. Limits on the neutral to charged current cross-section ratios $\text{R}{}_{\mathrm{v}}\text{=σ(v}\text{N}\text{→v}\text{N}\text{′π}{}^{\mathrm{o}}\text{)/2 σ(v}\text{N}\text{→ μ}{}^{\mathrm{-}}\text{N}\text{′π}{}^{\mathrm{o}}\text{)}$ and $\text{R}{}_{\mathrm{<mtext>\nu </mtext>}}\text{= σ(}\text{ν}\text{N}\text{→}\text{ν}\text{N}\text{′π}{}^{\mathrm{o}}\text{)/2 σ(}\text{ν}\text{N}\text{→ ω}{}^{\mathrm{+}}\text{N}\text{′π}{}^{\mathrm{o}}\text{)}$ are found to be $\text{0.10 < R}{}_{\mathrm{\nu }}\text{< 0.20}\text{and}\text{0.26 < R}{}_{\mathrm{<mtext>\nu </mtext>}}\text{< 0.44}$ at 68% confidence level.     

Breakdown of the one electron approximation for 4p core electron energy loss spectra in the rare earths

At high incident electron energies the 4p core electron energy loss features of clean La, Ce and Gd strongly resemble the corresponding XPS spectrum with evidence of strong 4p^-1 ? 4d^-2?f giant Coster-Kronig resonance in the “4p_{$\text{1}\text{2}$}” spectrum. The absence of charge transfer screening peaks in the $\text{4p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ loss of the oxides is attributed to localised 4p → 5d¹ excitation. As the primary energy approaches threshold, a satellite on the low energy side of the $\text{4p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ losses of La and Ce grows in intensity, due to excitations of multiples through non-dipole transitions.     

Study of the (α, 2α) reaction at 700 MeV

The results of a measurement of the cross section $\text{d}{}^3\text{σ/}\text{d}\text{Ω}{}_{\mathrm{\alpha 1}}\text{d}\text{Ω}{}_{\mathrm{\alpha 2}}\text{d}\text{E}$ for the (α, 2α) reaction on ⁶Li, ¹⁰B, C, O, Na, Al, Fe, Cu and Pb, are presented. Values for the effective cluster number n_0eff are deduced for these targets excluding lead, using the PWIA. It is observed that the PW1A value of n_eff is strongly dependent upon the theoretical shape assumed for the internal momentum distribution of the α-cluster. Using a S-state pole approximation for the momentum distribution leads to a value of the virtual decay amplitude g for A → α + (A ? 4) which is the same from ⁶Li to Fe.     

Kerr-effect and dielectric tensor elements of magnetite (Fe3O4) between 0.5 and 4.3 eV

The complex polar Kerr effect (rotation and ellipticity) of magnetite single crystals has been measured at room temperature between 0.5 and 4.3 eV. From the magneto-optical data and the optical constants, the off-diagonal elements (?_xy) of the dielectric tensor has been derived. Three well separated magneto-optical transitions have been indentified. At about 0.75 eV one strong magneto-optical structure with a diamagnetic line shape is assigned to a $\text{3d}{}^6\text{→3d}{}^5\text{(}{}^6\text{A}{}_{\mathrm{1g}}\text{) 4s}$ transition from Fe²⁺ in octahedral sites. Two other structures with paramagnetic line shapes near 1.85 and 2.90 eV are assigned to the orbital promotion processes $\text{3d}{}^6\text{(Fe}{}^{\mathrm{2+}}{}_{\mathrm{oct}}\text{)→3d}{}^5\text{(}{}^4\text{T}{}_{\mathrm{1g}}\text{) 4s}$ and $\text{3d}{}^5\text{(Fe}{}^{\mathrm{3+}}{}_{\mathrm{tet}}\text{)→3d}{}^4\text{(}{}^5\text{T}{}_2\text{) 4s}$, respectively, which take into account Fe 3d^n?1 final state effects.     

A study of the reactions d + p → τ + π0 and d + p → τ + η0

The reactions d + p → τ + π⁰ and d + p → τ + η⁰ were studied using the missing-mass method for incident deuteron momenta between 2.8 and $\text{3.8}\text{GeV}\text{c}$. The angular distributions show a peak in the forward direction ($\text{θ}{}_{\mathrm{\tau }}{}^1\text{= 0°}$) and are flat in the backward direction. The differential cross sections at $\text{θ}{}_{\mathrm{\tau }}{}^1\text{= 180°}$ for both reactions show a maximum for total center-of-mass energies near 3.46 GeV.     

Quadruple correlation functions and their application in double polarization experiments and in few-body problems

We define real functions which form a complete, orthogonal and rotational invariant basis for all problems depending on four directions. Their usefulness is demonstrated for processes of the type $\text{a}\text{+}\text{b}\text{→}\text{c}\text{+}\text{d}\text{,}\text{a}\text{+}\text{b}\text{→}\text{c}\text{+}\text{d}\text{,}\text{a}\text{+}\text{b}\text{→}\text{c}{}_1\text{, +}\text{c}{}_2\text{+}\text{d}$. The special case of all four directions in one plane has many applications too, e.g. in two- and three-body problems.     

Search for 4n IN π− double charge exchange reactions with heavy nuclei

A search for the existence of the tetraneutron has been made using the double charge exchange reaction $\text{π}{}^{\mathrm{?}}\text{+}{}^{208}\text{Pb}\text{→}{}^4\text{n + π}{}^{\mathrm{+}}\text{+}$ residuals for ⁴n production and the capture process in the same target, ${}^{208}\text{Pb}\text{+}{}^4\text{n}\text{→}{}^{212}\text{Pb}\text{+ γ}$, for the ⁴n detection. No event has been found, giving an upper limit for the product of the production cross section σ_p, the detection cross section σ_d and the ⁴n lifetime τ. Assuming 10^?18 ≦ τ ≦ 10^?9 sec it follows that σ_pσ_dτ ≦ 2.5 × 10^?65cm⁴ sec with 90 % confidence, and for $\text{τ ≧ 10}{}^{\mathrm{?9}}\text{sec}\text{, σ}{}_{\mathrm{<mtext>p</mtext>}}\text{σ}{}_{\mathrm{<mtext>d</mtext>}}\text{≦ 2.5 × 10}{}^{\mathrm{?56}}\text{cm}{}^4$ with 90 % confidence. The magnitude of this value is comparable to the experimental limit of the ⁴He(π^?, π⁺)⁴n cross section.     

The reactions K−p → K1− + nucleon at 3.13 and 3.3 GeV/c

Results are presented of a 12 event/μb bubble-chamber experiment; the reactions discussed in detail are $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^1\text{(890)}{}^{\mathrm{?}}\text{p, K}{}^1\text{(1420)}{}^{\mathrm{?}}\text{p and K}{}^1\text{(890)}{}^{\mathrm{?}}\text{Δ}{}^{\mathrm{+}}$.The K¹ (890)^?p channel is dominated by the forward peak. The suggestion of flattering at cos θ = 1 is more pronounced in $\text{(?}{}_{11}\text{+ ?}{}_{\mathrm{1?1}}\text{)}\text{d}\text{σ}\text{d}\text{t}$; which is mainly natural-parity exchange. Pseudoscalar exchange contributes to $\text{?}{}_{00}{}^{\mathrm{J}}\text{d}\text{σ}\text{d}\text{t}$; this is more sharply peaked in t. The value of $\text{(?}{}_{11}\text{? ?}{}_{\mathrm{1?1}}\text{)}\text{d}\text{σ}\text{d}\text{t}$ is somewhat larger than the upper limit from the dominant natural-parity exchange. There is significant structure in $\text{?}{}_{00}{}^{\mathrm{H}}\text{d}\text{σ}\text{d}\text{t}\text{at}\text{t ≈ ?0.6 (}\text{GeV}\text{/c)}{}^2$.The K¹ (1420)^?p channel is much more pronounced at 3.3 GeV/c than at 3.13 GeV/c, but is not markedly peripheral. The width of the K¹ (1420) in the 3.3 GeV/c data is 42 ± 12 MeV/c².The cross section for $\text{K}{}^{\mathrm{1?}}\text{Δ}{}^{\mathrm{+}}$ agrees with that expected from $\text{K}{}^{\mathrm{+}}\text{p}\text{→}\text{K}{}^1\text{Δ}$, assuming a single t-channel exchange. Our measured density matrix elements are consistent with a strong pseudoscalar exchange.     

Magnetic circular dichroism of transition metal ions in solids—II K2NaGaF6: Cr3+

The absorption and MCD spectra of the ${}^4\text{A}{}_{\mathrm{2g}}\text{→}{}^4\text{T}{}_{\mathrm{2g}}$, ${}^4\text{A}{}_{\mathrm{2g}}$, ${}^4\text{A}{}_{\mathrm{2g}}\text{→}{}^4\text{T}{}_{\mathrm{1g}}{}^{\mathrm{a}}$ and ${}^4\text{A}{}_{\mathrm{2g}}\text{→}{}^4\text{T}{}_{\mathrm{1g}}{}^{\mathrm{b}}$ spin-allowed transitions of Cr³⁺ in K₂NaGaF₆ are reported. It is shown that transitions to the ${}^4\text{T}{}_{\mathrm{1g}}$. states are induced by T_1u vibratio the other spin-allowed transition, ${}^4\text{A}{}_{\mathrm{2g}}\text{→}{}^4\text{T}{}_{\mathrm{2g}}$, there are three competing intensity mechanisms: electric dipole induced by T_1u vibrations, electric dipole induced by T_2u vibrations and magnetic dipole, and an estimate is made of the relative importance of these. The magnetic dipole ${}^4\text{A}{}_{\mathrm{2g}}\text{→}{}^2\text{E}{}_{\mathrm{g}}$ zero-phonon line is observed to be accompanied by a vibrational sideband for which the coupling is predominantly with T_2u vibrations. Other weak transitions are observed in MCD spectra and their origin briefly discussed.     

X-band ESR studies of forbidden transitions of europium ions in CaF2: Eu crystals

The characteristics of allowed and forbidden transitions of Eu²⁺ ions in CaF₂ single crystals have been investigated at room temperature. The Angular dependences of these transition intensities were theoretically calculated with the use of perturbation theory, and compared with the experimental values. The experimental results can be explained by taking into account crystal field effects $\text{(}\text{1}\text{60}\text{) b}{}_4\text{[O}{}^0{}_4\text{+ 5O}{}^4{}_4\text{]}$, and a hyper fine interaction A_iS · I_i in the spin Hamiltonian.     

Half-life of the h9/2 shell-model intruder-state isomer Au

The half-life of the $\text{9}\text{2}{}^{\mathrm{?}}$ shell-model intruder-state isomer in ¹⁸⁷Au has been measured by employing a technique in which each incoming event is tagged with a digital representation of time by means of a real-time clock. With this method we obtain a 2.3 ± 0.1 sec half-life for the $\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{→}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ E3 isomeric transition resulting in a retardation of 50 relative to the Weisskopf single-particle estimate.