K → πππγ in chiral perturbation theory

We present a complete analysis K → 3ππγ decays to (p ⁴) in the low-energy expansion of the Standard Model. We employ the notion of “generalized bremsstrahlung” to take full advantage of experimental information on the corresponding non-radiative K → 3π decays     

Search for CP violation in Z0 → τ + τ − and an upper limit on the weak dipole moment of the τ lepton

An improved test of invariance in the reaction e⁺e^? τ ⁺ τ ^? on the Z0 peak is performed using the data sample recorded between 1991 and 1995 with the OPAL detector at LEP. Optimal observables, requiring the reconstruction of the τ flight direction and spin, have been used for different final state topologies. From the non-observation of violation we derive 95% confidence level upper limits on the real and imaginary parts of the weak dipole moment of the τ lepton of |Re(d _τ ^w (m _Z ² | < 5.6 × 10^?18 e cm and |Im(d _τ ^w (m _Z ² ))| < 1.5 × 10^?17 e cm, respectively.     

Leptoquark pair production in hadronic interactions

The scalar and vector leptoquark pair production cross sections in hadronic collisions are calculated. In a model independent analysis we consider the most general C and P conserving couplings of gluons to both scalar and vector leptoquarks described by an effective low-energy Lagangian which obeys SU(3)_c invariance. Analytical expressions are derived for the differential and integral scattering cross sections including the case of anomalous vector leptoquark couplings, K _G and Λ_G, to the gluon field. Numerical predictions are given for the kinematic range of the TEVATRON and LHC. The pair production cross sections are also calculated for the resolved photon contributions to at HERA and LEP ? LHC, and for the process at possible future e ^{+ e ?} linear colliders and γγ colliders. Estimates of the search potential for scalar and vector leptoquarks at present and future high energy colliders are given.     

Particle-quadrupole and particle-octupole coupled states in 145Sm

In the present paper we present part of the results obtained in the study of above-yrast states in ¹⁴⁵Sm using the ¹⁴²Nd(α,Xnγ) reaction. γ-γ, angular distribution, polarization, and excitation function measurements were performed. All multiplet members of the and the multiplets have been observed. The unperturbed energies for the multiplet have been estimated using the extensive information existing on one neutron transfer reactions. The results are compared with the ¹⁴³Nd case. The similarity is remarkable.     

Decoherence induced by magnetic impurities in a quantum hall system

Scattering by magnetic impurities is known to destroy coherence of electron motion in metals and semiconductors. We investigate the decoherence introduced in a single act of electron scattering by a magnetic impurity in a quantum Hall system. For this, we introduce a fictitious nonunitary scattering matrix for electrons that reproduces the exactly calculated scattering probabilities. The strength of decoherence is identified by the deviation of eigenvalues of the product from unity. Using the fictitious scattering matrix, we estimate the width of the metallic region at the quantum Hall effect inter-plateau transition and its dependence on the exchange coupling strength and the degree of polarization of magnetic impurities.     

g-factors of rotational states in 176Hf, 177Hf,and 180Hf

g-factors of rotational states in ¹⁷⁶Hf and ¹⁸⁰Hf were measured with the twelve detector IPAC-apparatus of our laboratory [1]. The natural radioactivity 3.78 · 10¹⁰y ¹⁷⁶Lu and the 5.5 h isomer ^180mHf were used which populate the ground-state rotational bands of ¹⁷⁶Hf and ¹⁸⁰Hf. The integral rotations of γ-γ directional correlations in strong external magnetic fields and in static hyperfine fields of (Lu → Hf)Fe₂ and HfFe₂ were observed. The following results were obtained: The hyperfine field in (Lu → Hf)Fe₂ was calibrated by observing the integral rotation of the 9/2^? first excited state of ¹⁷⁷Hf populated in the decay of 6.7d ¹⁷⁷Lu. The g-factor of this state was redetermined in an external magnetic field as Finally the g-factor of the 2 ₁ ⁺ state of ¹⁷⁶Hf was derived from the measured g(2 ₁ ⁺ ) of ¹⁸⁰Hf by use of the precisely known ratio g(2 ₁ ⁺ , ¹⁷⁶Hf)/g(2₁ ⁺, ¹⁸⁰Hf) [2] as      

How to search for doubly charmed baryons and tetraquarks

Possible experimental searches of doubly charmed baryons and tetraquarks at fixed target experiments with high energy hadron beams and a high intensity spectrometer are considered here. The baryons are: , and Ω _cc ⁺ ; and the tetraquark is T (ccud). Estimates are given of masses, lifetimes, internal structure, production cross sections, decay modes, branching ratios, and yields. Experimental requirements are given for optimizing the signal and minimizing the backgrounds. This paper is designed as an experimental and theoretical review. It may therefore be of assistance in the planning for a future state-of-the-art high statistics charm experiment, in the spirit of the aims of the recent CHARM2000 workshop.     

Spin effects in two-body hadronic decays of the B c mesons

Spin effects in the weak two-body hadronic decays of the B _c and B _c ^* mesons into J/ψ and ρ(π) mesons are considered within the model of hard one-gluon exchange between quarks at high momentum transfers. It is shown that the polarization of the J/ψ meson in the decays of the B _c ^* meson differs substantially from that in the decays of the B _c ^* meson. The decay widths of the B _c ^* meson differ significantly from the widths of the B _c ^* meson.     

LEMS: application of the method to study the static quadrupole moment of the isomer in 179W

The method of the level mixing spectroscopy (LEMS) was applied for the first time for the study of the static quadrupole moments of high-K isomers in the A ≈ 180 mass region. Results from a preliminary experiment for the static quadrupole moment of the (750 ns) isomer in ¹⁷⁹W give a limit for its upper value Q < 7b, corresponding to a quadrupole deformation of β2< 0.343.     

On a symmetry topological classification of edge states in crystalline spin-Hall insulators with the time reversal invariance

Symmetry analysis reveals all types of singularities of the edge states in two-dimensional systems with a boundary (2D → 1D systems), which are invariant under time reversal. Symmetry reasons also provide the matching condition for material functions parameterizing the Hamiltonian at various points of the Brillouin zone. The unified parameterization of the Hamiltonian makes it possible to construct the mapping of trajectories closed in the quasimomentum k in the Brillouin zone into the SU(2) topological group. There are only two equivalence classes of Hamiltonians, which are given by the elements of the first fundamental group . The first type of surface states corresponds to a normal insulator and the second type corresponds to a topological spin-Hall insulator. Comparison with the classification based on the Pfaffian method is performed.     

Heavy baryons in the relativistic quark model

In the framework of the relativistic quasipotential quark model the mass spectrum of baryons with two heavy quarks is calculated. The quasipotentials for interactions of two quarks and of a quark with a scalar and axial vector diquark are evaluated. The bound state masses of baryons with are computed.     

Z 0 boson decays to B^{(*)}_{c} meson and its uncertainties

The planned new e ⁺ e ^? collider with high luminosity shall provide another useful platform to study the properties of the doubly heavy B _c meson in addition to the hadronic colliders as LHC and TEVATRON. In the ‘New Trace Amplitude Approach’, we calculate the production of the spin-singlet B _c and the spin-triplet $B^{*}_{c}$ mesons through the Z ⁰ boson decays, where uncertainties for the production are also discussed. Our results show $\varGamma_{(^{1}S_{0})}=81.4^{+102.1}_{-40.5}$  KeV and $\varGamma_{(^{3}S_{1})}=116.4^{+163.9}_{-62.8}$  KeV, where the errors are caused by varying m _b and m _c within their reasonable regions.     

Charge density excitations in bilayer graphene in high magnetic field

The charge-density excitations in bilayer graphene at the filling-factor ν 1 at small momenta are considered in the frame of the Hartree-Fock approximation. The presence of small asymmetry of graphene layers is included. The dependence of the magnetoplasmon energy on the bilayer ground state is shown. The energy splitting proportional to $ \sqrt H $ for the symmetric case with half-filled zero-energy levels is found both for bilayer and monolayer graphene.     

Monte Carlo Glauber model with meson cloud: predictions for 5.44 TeV Xe + Xe collisions

We study, within the Monte-Carlo Glauber model, centrality dependence of the midrapidity charged multiplicity density \(dN_{ch}/d\eta \) and of the anisotropy coefficients \(\varepsilon _{2,3}\) in Pb + Pb collisions at \(\sqrt{s}=5.02\) TeV and in Xe + Xe collisions at \(\sqrt{s}=5.44\) TeV. Calculations are performed for versions with and without nucleon meson cloud. The fraction of the binary collisions, \(\alpha \), has been fitted to the data on \(dN_{ch}/d\eta \) in Pb + Pb collisions. We obtain \(\alpha \approx 0.09(0.13)\) with (without) meson cloud. The effect of meson cloud on the \(dN_{ch}/d\eta \) is relatively small. For Xe + Xe collisions for 0–5% centrality bin we obtain \(dN_{ch}/d\eta \approx 1149\) and 1134 with and without meson cloud, respectively. We obtain \(\varepsilon _2(\mathrm {Xe})/\varepsilon _2(\mathrm {Pb})\sim 1.45\) for most central collisions, and \(\varepsilon _2(\mathrm {Xe})/\varepsilon _2(\mathrm {Pb})\) close to unity at Open image in new window . We find a noticeable increase of the eccentricity in Xe + Xe collisions at small centralities due to the prolate shape of the Xe nucleus. The triangularity in Xe + Xe collisions is bigger than in Pb + Pb collisions at Open image in new window . We obtain \(\varepsilon _3(\text{ Xe })/\varepsilon _3(\text{ Pb })\sim 1.3\) at Open image in new window .     

Infinitely many solutions for a perturbed nonlinear fractional boundary value problems depending on two parameters

In this paper we prove the existence and multiplicity of (weak) solutions for the following fractional boundary value problem: where $\alpha \in (\tfrac{1} {2},1]$ , ₀ D _t ^α?1 and _t D _T ^α?1 are the left and right Riemann-Liouville fractional integrals of order 1 ? α respectively, λ,μ ∈ [0,+∞), T > 0, F,G ∈ C([0,T] × R ^N ;R)\{0} and A = (a _ij (t)) _N×N is symmetric. Our approach is based on variational methods.     

S toP wave form factors in semi-leptonicB decays

We apply HQET to semi-leptonicB andB _s meson decays into the observed charmedp wave states. In order to examine the sensitivity of the results to the choice of a specific model, we perform all calculations using several different meson models, and find that uncertainty introduced by the choice of a particular model is about 30%. Specifically, assuming?? _B=1.50ps andV _cb=0.040, we obtain branching ratios of (0.27±0.08)% and (0.45±0.14)% for $B \to D_1 l\bar \upsilon _1 $ and $B \to D_2^* l\bar \upsilon _1 $ decays, respectively.     

An efficient and facile synthesis of 3-amino-5-chromenyl-butenolides from 3-formyl chromone, dialkyl acetylenedicarboxylate, and primary amines

A three-component reaction of 3-formyl chromones, dialkyl acetylenedicarboxylate, and isocyanides in the presence of $\text{ POCl}_{3}$ was used as a highly efficient and practical approach for the synthesis of 3-amino-5-chromenyl-butenolides. High yields and high bond forming efficiency, and simple operations are the advantages of this method. Graphical abstract      

S toP wave form factors in semi-leptonicB decays

We apply HQET to semi-leptonicB andB _s meson decays into the observed charmedp wave states. In order to examine the sensitivity of the results to the choice of a specific model, we perform all calculations using several different meson models, and find that uncertainty introduced by the choice of a particular model is about 30%. Specifically, assumingτ _B=1.50ps andV _cb=0.040, we obtain branching ratios of (0.27±0.08)% and (0.45±0.14)% for $B \to D_1 l\bar \upsilon _1 $ and $B \to D_2^* l\bar \upsilon _1 $ decays, respectively.     

Motions of vortex patches

An evolution equation describing the motion of vortrex patches is established. The existence of steady solutions of this equation is proved. These solutions arem-fold symmetric regions of constant vorticity ω₀ and are uniformly rotating with angular velocity Ω in the range $$\tilde \Omega _{m - 1}< \tilde \Omega \leqslant \tilde \Omega _m (\tilde \Omega = \Omega /\omega _0 ,m \geqslant 2)$$ where \(\tilde \Omega _m = (m - 1)/2m\) . We call this class, ofm-fold symmetric rotating regionsD, the class of them-waves of Kelvin. Any may be regarded as a simply connected region which is a stationary configuration of the Euler equations in two dimensions. If then any magnification, rotation or reflection is also in with the same angular velocity Ω ofD. The angular velocity \(\Omega _m = \tilde \Omega _m \omega _0 \) corresponds only to the circle solution, which is a trivial member of every class ,m?2. The class corresponds to the rotating ellipses of Kirchoff. Other properties of the class are established.     

Scaling for a random polymer

LetQ _n ^β be the law of then-step random walk on ?^d obtained by weighting simple random walk with a factore ^?β for every self-intersection (Domb-Joyce model of “soft polymers”). It was proved by Greven and den Hollander (1993) that ind=1 and for every β∈(0, ∞) there exist θ^*(β)∈(0,1) and such that under the lawQ _n ^β asn→∞: $$\begin{array}{l} (i) \theta ^* (\beta ) is the \lim it empirical speed of the random walk; \\ (ii) \mu _\beta ^* is the limit empirical distribution of the local times. \\ \end{array}$$ A representation was given forθ ^*(β) andµ _β ^β in terms of a largest eigenvalue problem for a certain family of ? x ? matrices. In the present paper we use this representation to prove the following scaling result as β?0: $$\begin{array}{l} (i) \beta ^{ - {\textstyle{1 \over 3}}} \theta ^* (\beta ) \to b^* ; \\ (ii) \beta ^{ - {\textstyle{1 \over 3}}} \mu _\beta ^* \left( {\left\lceil { \cdot \beta ^{ - {\textstyle{1 \over 3}}} } \right\rceil } \right) \to ^{L^1 } \eta ^* ( \cdot ) . \\ \end{array}$$ The limitsb ^*∈(0, ∞) and are identified in terms of a Sturm-Liouville problem, which turns out to have several interesting properties. The techniques that are used in the proof are functional analytic and revolve around the notion of epi-convergence of functionals onL ²(?⁺). Our scaling result shows that the speed of soft polymers ind=1 is not right-differentiable at β=0, which precludes expansion techniques that have been used successfully ind≧5 (Hara and Slade (1992a, b)). In simulations the scaling limit is seen for β≦10^?2.