Radiative <Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>3</Subscript> decays revisited

Motivated by recent experimental results and ongoing measurements, we review the chiral perturbation theory prediction for decays. Special emphasis is given to the stability of the inner bremsstrahlung-dominated relative branching ratio versus the K _e3 form factors, and on the separation of the structure-dependent amplitude in differential distributions over the phase space. For the structure-dependent terms, an assessment of the order p ⁶ corrections is given, in particular, a full next-to-leading order calculation of the axial component is performed. The experimental analysis of the photon energy spectrum is discussed, and other potentially useful distributions are introduced.Received: 9 December 2004, Published online: 21 February 2005PACS: 13.20.Eb, 11.30.Rd, 12.39.Fe     

<Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>3</Subscript> decays and CKM unitarity

We present a detailed numerical study of the K_e3 decays to in chiral perturbation theory with virtual photons and leptons. We describe the extraction of the CKM matrix element |V_us| from the experimental K_e3 decay parameters. We propose a consistency check of the K ⁺ _e3 and K⁰_e3 data that is largely insensitive to the dominating theoretical uncertainties, in particular the contributions of . Our analysis is highly relevant in view of the recent high statistics measurement of the K ⁺ _e3 branching ratio by E865 at Brookhaven which does not indicate any significant deviation from CKM unitarity but rather a discrepancy with the present K⁰_e3 data.Received: 22 January 2004, Published online: 30 April 2004Work supported in part by IHP-RTN, Contract No. HPRN-CT2002-00311 (EURIDICE) and by Acciones Integradas, Project No. 19/2003 (Austria), HU2002-0044 (MCYT, Spain)     

<Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>3</Subscript> Decay Studies in the OKA Experiment

Recent results from OKA setup concerning form factor studies in K_e3 decay are presented. About 5.25 M events obtained for decays of 17.7 GeV/cK⁺ are selected for the analysis. The linear and quadratic slopes for the decay form factor f₊(t) are measured: λ'₊ = 2.95 ± 0.022 ± 0.018 × 10 ^-2 for the linear slope fit and λ₊ = 2.611 ± 0.035 ± 0.028 × 10 ^-2, λ"₊ = 1.91 ± 0.19 ± 0.14 × 10 ^-3 for the quadratic one. The scalar and tensor contributions are compatible with zero. Several alternative parametrizations are tried: the Pole fit parameter is found to be M _V = 891 ± 3 MeV; the parameter of the dispersive parametrization is measured to be Λ₊ = 2.458 ± 0.018 × 10^-2.     

<Emphasis Type="Italic">B</Emphasis><Subscript><Emphasis Type="Italic">K</Emphasis></Subscript> from the lattice with Wilson quarks

We report our results for the bag parameter B _K obtained from the quenched simulations on the lattice with Wilson fermions for three values of the lattice spacing. We implemented the method by which no subtraction of the mixing with other four-fermion operators is needed. Our final result, in terms of the renormalization group invariant bag parameter, is .Received: 9 July 2004, Revised: 27 July 2004, Published online: 21 September 2004     

The electromagnetic effects in <Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>4</Subscript> decay

The final-state interaction of pions in K _e4 decay allows to obtain the value of the isospin and angular-momentum-zero ππ scattering length a ₀ ⁰ .We take into account the electromagnetic interaction of pions and isospin-symmetry-breaking effects caused by different masses of neutral and charged pions and estimate the impact of these effects on the procedure of scattering-length extraction from K _e4 decays.     

The isospin-symmetry-breaking effects in <Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>4</Subscript> decays

The final-state interaction of pions in K _e4 decay allows to obtain the value of the isospin and angular-momentum-zero ππ scattering length a ₀⁰.We take into account the electromagnetic interaction of pions and isospin-symmetry-breaking effects caused by different masses of neutral and charged pions and estimate the impact of these effects on the procedure of scattering-length extraction from K _e4 decays.     

Polynomial Realization of <Emphasis Type="Italic">s</Emphasis>l<Subscript><Emphasis Type="Italic">q</Emphasis></Subscript>(2) and Fusion Rules at Exceptional Values of <Emphasis Type="Italic">q</Emphasis>

Representations of the sℓ_q(2) algebra are constructed in the space of polynomials of real (complex) variable for q^N=1. The spin addition rule based on eigenvalues of Casimir operator is illustrated on few simplest cases and conjecture for general case is formulated.     

Fermion Localization on the <Emphasis Type="Italic">orbifold</Emphasis><Emphasis Type="Italic">S</Emphasis><Subscript>1</Subscript>/<Emphasis Type="Italic">Z</Emphasis><Subscript>2</Subscript>

The hierarchical structure of fermion masses of the Standard Model is explained in split fermion models by localizing the fermions at different points in an extra dimension. We consider split fermion models with two bulk scalars compactified on an orbifold. In the static case we find analytical expression for the localizer. We also address the issue of stability of the localizer. We also find exact solutions for the fermion zero modes. We explore the parameter space of the model. We find ample opportunity for construction of phenomenologically viable theories exist.     

<Emphasis Type="Italic">B</Emphasis> and <Emphasis Type="Italic">B</Emphasis><Subscript><Emphasis Type="Italic">s</Emphasis></Subscript> decay constants from moments of finite energy sum rules in QCD

We use an appropriate combination of moments of finite energy sum rules in QCD in order to compute the B _q -meson decay constants f _B and . We perform the calculation using a two-loop computation of the imaginary part of the pseudoscalar two point function in terms of the running bottom quark mass. The results are stable against the so-called QCD duality threshold, and they are in agreement with the estimates obtained from Borel transform QCD sum rules and lattice computations.Received: 28 July 2004, Revised: 10 September 2004, Published online: 23 November 2004PACS: 12.38.Bx, 12.38.LgSupported by MCYT-FEDER under contract FPA2002-00612.     

Surface superconductivity and<Emphasis Type="Italic">H</Emphasis><Subscript><Emphasis Type="Italic">c3</Emphasis></Subscript> in UPt<Subscript>3</Subscript>

Ginzburg-Landau (GL) theory is used to study surface superconductivity for UPt₃ for various order parameter symmetries (OPS), andH _c3 is found for all principal directions of the surface normal\(\hat n\) and the field [1]. Assuming specular reflection, and allowing for reorientation of the antiferromagnetic symmetry breaking field in the models withE _1g ,E _2g ,E _1u , orE _2u symmetry, the experiments of Keller et al. [2] with\(\hat n = \hat a\) can be qualitatively explained for all OPS except possiblyA _1u ⊕B _1u . The implied GL parameters then predict qualitatively different and OPS dependent behavior for\(\hat n = \hat a^* \) and\(\hat n = \hat c\). Study ofH _c3 for these surfaces would give strong clues about the OPS of UPt₃.     

Discrete breathers in biatomic crystals of <Emphasis Type="Italic">AB</Emphasis> and <Emphasis Type="Italic">A</Emphasis><Subscript>3</Subscript><Emphasis Type="Italic">B</Emphasis> composition

The conditions for the existence of discrete breathers (DBs) in biatomic crystals of AB and A ₃ B composition are established, and their properties are studied by means of molecular mechanics using the examples of CuAu and Pt₃Al, respectively. The phonon spectra of the crystals are analyzed, and a gap in the phonon spectrum of CuAu is obtained via considerable homogeneous elastic strain. There is a gap in the phonon spectrum of the Pt₃Al crystal at zero strain, due to the considerable difference between the atomic weights of its components. The frequencies at which discrete breathers can exist in the considered crystals are determined. The energy localized on different types of DBs is estimated. The propagation of a current pulse through Pt₃Al resulting in the excitation of DBs with mild nonlinearity is simulated.     

<Emphasis Type="Italic">B</Emphasis>-meson physics: <Emphasis Type="Italic">CP</Emphasis> violation and semileptonic decays

The paper represents a review of our present knowledge on the phenomenology of weak decays of quarks and their role in the determination of the parameters of the Standard Model. Specifically, we focus on CP violation in B decays and the determination of the Cabibbo-Kobayashi-Maskawa matrix element V_cb from exclusive and inclusive semileptonic B decays. We also briefly discuss phenomeno-logical applications concerning the electron energy spectra in inclusive semileptonic B and B_c decays.     

<Emphasis Type="Italic">SU</Emphasis>(3)-Instantons and <Emphasis Type="Italic">G</Emphasis><Subscript>2</Subscript>,<Emphasis Type="Italic">Spin</Emphasis>(7)-Heterotic String Solitons

Necessary and sufficient conditions to the existence of a hermitian connection with totally skew-symmetric torsion and holonomy contained in SU(3) are given. A formula for the Riemannian scalar curvature is obtained. Non-compact solution to the supergravity-type I equations of motion with non-zero flux and non-constant dilaton is found in dimension 6. Non-conformally flat non-compact solutions to the supergravity-type I equations of motion with non-zero flux and non-constant dilaton are found in dimensions 7 and 8. A Riemannian metric with holonomy contained in G₂ arises from our considerations and Hitchin’s flow equations, which seems to be new. Compact examples of SU(3),G₂ and Spin(7) instanton satisfying the anomaly cancellation conditions are presented.     

Entropy for <Emphasis Type="Italic">SU</Emphasis>(3)<Subscript><Emphasis Type="Italic">c</Emphasis></Subscript> quark states

We discuss the quantum state structure using the standard model for three colored quarks in the fundamental representations of SU(3)_c making up the singlet ground state of the hadrons. This allows us to calculate a finite von Neumann entropy from the quantum reduced density matrix, which we explicitly evaluate for the quarks in a model for the meson and baryon states.Received: 9 December 2003, Revised: 23 January 2004, Published online: 8 April 2004D.E. Miller: om0@psu.eduPermanent address: Department of Physics, Pennsylvania State University, Hazleton Campus, Hazleton, Pennsylvania, 18201 USA     

Summary on high <Emphasis Type="Italic">p</Emphasis><Subscript><Emphasis Type="Italic">T</Emphasis></Subscript> probes

Results on high-p _T probes shown at the Hard Probes 2008 Conference are summarized, with an appreciation of the improvements in precision of the measurements and experimental techniques since the beginning of RHIC operation. Particular attention is given to the latest measurements of the nuclear modification factor of identified particles, photon-hadron correlation measurements, and full jet reconstruction.     

Energy and system dependence of high-<Emphasis Type="Italic">p</Emphasis><Subscript><Emphasis Type="Italic">T</Emphasis></Subscript> triggered two-particle near-side correlations

Previous studies have indicated that the near-side peak of high-p _T triggered correlations can be decomposed into two parts, the Jet and the Ridge. We present data on the yield per trigger of the Jet and the Ridge from d+Au, Cu+Cu and Au+Au collisions at GeV and 200 GeV and compare data on the Jet to PYTHIA 8.1 simulations for p+p. PYTHIA describes the Jet component up to a scaling factor, meaning that PYTHIA can provide a better understanding of the Ridge by giving insight into the effects of the kinematic cuts. We present collision energy and system dependence of the Ridge yield, which should help distinguish models for the production mechanism of the Ridge.     

Linearized interactions of scalar and vector fields with the higher spin field in <Emphasis Type="Italic">AdS</Emphasis><Subscript><Emphasis Type="Italic">D</Emphasis></Subscript>

The explicit form of linearized gauge arid generalized “Weyl invariant” interactions of scalar and general higher even spin fields in the AdS _D space constructed in [1] is reviewed. Also a linearized interaction of vector field with general higher even spin, gauge field is obtained. It is shown that the gauge invariant action of linearized vector field interacting with the higher spin field also includes the whole tower of invariant actions for couplings of the same vector field with the gauge fields of smaller even spin.     

The <Emphasis Type="Italic">q</Emphasis>-boson-fermion realizations of the quantum superalgebra <Emphasis Type="Italic">U</Emphasis><Subscript><Emphasis Type="Italic">q</Emphasis></Subscript>(<Emphasis Type="Italic">osp</Emphasis>(1/2))

We show that our construction of realizations for algebras and quantum algebras can be generalized to quantum superalgebras too. We studyan example of quantum superalgebra U _q (osp(1/2)) and give the boson-fermion realization with respect to one pair of q-boson operators and one pair of fermions.