Perhaps scalar neutrinos are the lightest supersymmetric partners

We consider the possibility that the scalar partners of the neutrinos $\text{(}\text{v}\text{)}$ are the least massive supersymmetric partners, and show that this alternative is compatible with cosmological constraints, which put a significant lower bound on photino masses but not on $\text{v}$ masses. Various consequences are examined: the photon counting rate for $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{-}}\text{→γ}\text{v}$$\text{v}\text{?}\text{?}$ may be large; the rate for $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{-}}\text{→}\text{W}{}^{\mathrm{+}}\text{a}\text{W}{}^{\mathrm{-}}$ by $\text{v}$ exchange is enhaced; Z⁰→ increases Γ(Z⁰) by about 0.25 GeV; $\text{W}{}^{\mathrm{\pm }}\text{→}\text{?}{}^{\mathrm{+-}}\text{v}$ may be enhanced; the decay $\text{τ→}\text{v}{}_{\mathrm{\tau }}\text{?}{}_{\mathrm{?}}$$\text{v}\text{?}\text{?}$ may be detectable; there can be additional contributions to the rare decay $\text{K}{}^{\mathrm{+}}\text{→π}{}^{\mathrm{+}}\text{v}$$\text{v}\text{?}\text{?}$; restrictions on gluino masses, which depend on photinos interacting before they decay, have to be re-examined; scalar neutrinos have suitable characteristics as candidates for dark matter in the universe. We discuss one currently fashionable class of models that can predicr a light $\text{v}$.     

Chiral lagrangian calculation of nucleon decay modes induced by d=5 supersymmetric operators

We consider the general baryon-number violating operators which are produced by dressing the supersymmetric dimension-five operators by gaugino exchanges. We then use chiral dynamics to calculate the widths for the decay modes $\text{p}\text{→}\text{K}{}^{\mathrm{+}}\text{ν}{}_{\mathrm{d}}\text{,}\text{K}{}^0\text{e}{}_{\mathrm{d}}{}^{\mathrm{+}}\text{,}\text{and n}\text{→}\text{k}{}^0\text{ν}{}_{\mathrm{d}}$. The resulting branching ratios are rather sensitive to the precise admixture of the various baryon-number violating operators involved. In particular the decay mode $\text{p}\text{→}\text{K}{}^{\mathrm{+}}\text{ν}{}_{\mathrm{d}}$ is generally dominant in qualitative agreement with previous quark model results.     

Decays of charmed mesons via color-octet decays of the c-quark

We unify the color-octet weak transitions first studied in cq? annihilation models with the coherence structure of c-quark decay models. We find then, with a dominant c-quark decay contribution, $\text{2.3,?}{}_{\mathrm{\tau }}\text{(}\text{D}{}^{\mathrm{+}}\text{)}\text{τ(}\text{D}{}^0\text{)?3.0}$ and τ(D⁺)≈7.5×10^?13 s, not inconsistent with the trends in the experimental results.     

Baryon asymmetry and nucleon decay in supersymmetric guts

In a class of supersymmetric GUTs with a coloured Higgs sector of an intermediate mass, we study nucleon decay and the generation of baryon assymmetry. We find that: (a) a non-vanishing baryon asymmetry can be generated by the decay of coloured Higgs bosons and Higgs fermions into quarks and squarks; (b) nucleons decay at a rate 10^?31 yr^?1 preferably to $\text{μ}{}^{\mathrm{+}}\text{K}{}^0\text{,}\text{ν}{}_{\mathrm{\mu }}\text{K}{}^{\mathrm{+}}$ while decay involving dimension-five operators is kinematically excluded.     

Memory function for cyclotron resonance of two-dimensional electron systems

Coulomb effects on cyclotron resonance in two-dimensional electron systems are investigated based on a self-consistent approach which improves the random-phase approximation. The memory function in the dynamic magnetoconductivity depends on the electron density not only through the filling factor v but also on its combination with the dimensionless density parameter r_s in the form $\text{r}{}_{\mathrm{s}}\text{v}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$. The memory function reproduces the data of Wilson, Allen and Tsui for intermediate densities.     

Nucleon decay in supersymmetric models via gluino dressed graphs

Dimension-five baryon-number-violating operators may contribute to proton decay via gaugino exchange, which converts then to the usual dimension-six operators. We show that gluino-exchange contributions may be expected to dominate for a large top quark mass (m_t > 40 GeV). In this case the dominant decay modes are $\text{p → K}{}^0\text{μ}{}^{\mathrm{+}}\text{, K}{}^{\mathrm{+}}\text{ν}\text{and}\text{n →}\text{ν}\text{K}{}^0\text{, μ}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{, K}{}^0\text{π}{}^{\mathrm{?}}\text{μ}{}^{\mathrm{+}}$. We also estimate the decay lifetime.     

On the calculation of dielectric properties from computer simulations

We report a reaction field calculation for Stockmayer particles at reduced density $\text{?}{}^1\text{= 0.8}$, reduced temperature $\text{T}{}^1\text{= 1.35}$ and reduced dipole moment $\text{μ}{}^1\text{= 1.64}$ using a relatively large cutoff distance for the dipolar interaction. The dipole-dipole correlation function is compared with corresponding simulations using truly periodic boundary conditions. The mean square fluctuation of the total dipole moment are shown to exhibit a long period oscillation, precluding a determination of the dielectric constant with an accuracy better than 15%, in a Monte-Carlo calculation of the order of 5 × 10⁶ configurations.     

Transport in two dimensions. II the thermal conductivity coefficient

The study of generalized transport coefficients in two dimensions is continued. In this article, the thermal conductivity coefficient is examined. The Mori formalism is used and the set of variables consists of all finite multilinear products of two collective conserved variables, the energy density and the momentum density. The tensorial symmetry of Euler and dissipative matrix elements is taken into account explicitly. Two simultaneous non-linear integral equations are obtained, the asymptotic solution for which behave in the same manner as the self-diffusion coefficient studied in an earlier paper. However, the coefficient is dependent upon the intermolecular potential. The heat current auto-correlation function decays asymptotically as $\text{[t}\text{In}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{t]}{}^{\mathrm{?1}}$. The asymptotic form for the shear viscosity coefficient is examined briefly and found to be independent of the intermolecular potential. A better approximation for the coefficient of the asymptotic form of the self-diffusion coefficient is presented.     

Final state gluon effects in charmed meson decays

In the valence-quark c-decay scheme the decay $\text{D}{}^0\text{→}\text{K}{}^0\text{π}{}^0$ is expected to be strongly suppressed. We suggest that final state soft gluon exchange may account for the rather large branching ratio recently measured for this process, and study two-body decays of charmed mesons in our new scheme.     

Transport in two dimensions. I the self-diffusion coefficient

The Mori formalism is used to study generalized transport coefficients in two dimensions. All finite multilinear products of the single particle density and momentum density comprise the set of the variables in the calculation of the self-diffusion coefficient. A self-consistent equation, which is a non-linear integral equation, is obtained for the leading asymptotic behavior of the generalized self-diffusion coefficient. An asymptotic solution is presented which for small wavevector (k) and frequency (s) behaves like $\text{In}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(s + k}{}^2\text{D)}{}^{\mathrm{?1}}$, where D has the dimensions of a diffusion coefficient. The mean square and mean fourth displacements of a tagged particle are also calculated. The long time behavior of the momentum correlation function exhibits a tail of the form $\text{[t}\text{In}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(t)]}{}^{\mathrm{?1}}$ whose coefficient is dependent of the intermolecular potential.     

On the possibility of a search for a supersymmetric channel of proton decay p→K+ν, with lifetime around 1033 years

A search for a characteristic supersymmetric channel of proton decay, $\text{p}\text{→}\text{K}{}^{\mathrm{+}}\text{ν}$, is discussed in the paper. From calculations of background produced by atmospheric neutrinos, the lifetime $\text{τ(}\text{p}\text{→}\text{K}{}^{\mathrm{+}}\text{ν}\text{)<3×10}{}^{32}\text{y}$ is derived as the upper limit for possible measurements using water-Cherenkov detectors. It is shown that liquid-scintillation detectors have a much better signature for this channel of proton decay.At the same time background produced by atmospheric neutrinos with a signature of $\text{p}\text{→}\text{K}{}^{\mathrm{+}}\text{ν}$ decay in liquid-scintillation detectors is lower and can be further suppressed using some observational criteria.The possibility of searching for $\text{p}\text{→}\text{K}{}^{\mathrm{+}}\text{ν}$ proton decay with lifetime ～10³³ y using a 4–10 kiloton (kt) liquid-scintillation detector is discussed.     

Rare decay modes of K1(1420) and K1(892)

A 2.5 standard deviation signal is observed for the decay $\text{K}{}^{\mathrm{1?}}\text{(1420) →}\text{K}{}^{\mathrm{1?}}\text{(892)π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}$. From this signal a partial width of 13.0 ± 5.0 MeV for the decay mode $\text{K}{}^1\text{(1420)→}\text{K}{}^1\text{(892)ππ}$ is deduced under the assumption that the ππ system is in an I = 1 state. For the rare decay mode $\text{K}{}^1\text{(892)→}\text{K}\text{ππ}$ no signal is observed. The following upper limits can be given for the decay widths: , , .     

The case against factorization with vacuum insertion in quark decay graphs for non-leptonic decays

We show that factorization with vacuum insertion, an assumption often made for quark decay topologies in non-leptonic decays (e.g. by the authors of the annihilation model for $\text{D}\text{→}\text{K}\text{π}$), overestimates the absolute magnitude of ($\text{D}{}^{\mathrm{+}}\text{→}\text{K}{}^0\text{π}{}^{\mathrm{+}}$) by a factor 5. It also fails for $\text{ΔI =}\text{3}\text{2}$ hyperon decays.     

Ellipsometric investigation of the skeletonization process of langmuir-blodgett films

When Langmuir-Blodgett films, consisting of a mixture of a long chain carboxylic acid and its salt are immersed in benzene, the acid dissolves, while the salt remains as a skeleton. The density of the film is lowered in this way and so is the refractive index. The process can thus be followed by performing ellipsometric measurements as a function of time of skeletonization. It is established that skeletonization is, in first instance, a diffusion-controlled process with a diffusion coefficient of about $\text{5 × 10}{}^{\mathrm{?14}}\text{cm}{}^2\text{sec}$ at room temperature. The salt also slowly dissolves at a rate of about $\text{1.6 × 10}{}^{10}\text{molecules}\text{/}\text{sec}\text{cm}{}^2$.     

On a least upper bound Tc of superconductors with paramagnetic impurities

We have obtained a least upper bound, $\text{k}{}_{\mathrm{B}}\text{T}{}_{\mathrm{c}}\text{? c(μ}{}^1\text{, t)A}$, on the critical temperature T_c of an isotropic superconductor with paramagnetic impurities described by the scattering matrix t for fixed values of μ¹. We have also obtained the corresponding optimal spectrum $\text{α}{}^2\text{F(m) = Aδ[ω?d(μ}{}^1\text{, A]}$. The numerical results for the functions $\text{c(μ}{}^1\text{, t)}\text{and}\text{d(μ}{}^1\text{, t)}$ are presented for $\text{α}{}^1\text{= 0.1}$ and 0.16 in the form of universal curves representing $\text{c(μ}{}^1\text{, t)}\text{and}\text{d(μ}{}^1\text{, t)}$ as functions of the reduced impurity concentration $\text{t}\text{= t/A}$. We have also established an upper limit to the reduced critical concentration $\text{t}{}_{\mathrm{crit}}$ for an arbitrary shape of α²F(ω)1.     

Anomalous events in e+e−→μ+μ−γ. excited states and/or new interactions?

We first show that the enhancement observed by Cello can neither be explained by real or virtual μ¹ production through μ¹μγ or μ¹μZ couplings nor by μμγγ or μμγZ contact terms, when one imposes the usual constraints from $\text{g -2, e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→γγ, Z→}\text{ll}\text{γ}$. We then propose an explanation using an eeμμ¹ contact term which is less constrained. In addition to $\text{μ}{}^1\text{→μγ}$ this leads to a direct decay $\text{μ}{}^1\text{→μee}$. Generalized to other types of fermion pairs we have here an interesting source of multifermion anomalous events.     

K-K mixing in the standard model

We present a new calculation of the B parameter which governs the short distance contribution to the $\text{K}{}^0\text{-}\text{K}{}^0$ off-diagonal mass matrix. The calculation combines the information provided by the effective chiral lagrangian realization of QCD at long distances with the perturbative behaviour of QCD at short distances via the local duality approach. The result exhibits an explicit renormalization scale dependence which exactly cancels with the corresponding dependence in the Wilson coefficient.     

The beta decay of 137Cs

Evidence is presented to support the view that the approximate shape factor $\text{C = q}{}^2\text{+}\text{b}\text{?}\text{p}{}^2$ does not adequately describe the second-forbidden beta decay of ¹³⁷Cs. An improved formula is given, with single-particle estimates of the nuclear matrix-element ratios. According to this model the coefficient of p² involves considerable cancellation between matrix elements; when due allowance is made for this, good fits to the experimental data are obtained, leading to better estimates of the decay scheme parameters.