The KπK\pi form factors from Analyticity and Unitarity

Analyticity and unitarity techniques are employed to obtain bounds on the shape parameters of the scalar and vector form factors of semileptonic $K_{l3}$ decays. For this purpose we use vector and scalar correlators evaluated in pQCD, a low energy theorem for scalar form factor, lattice results for the ratio of kaon and pion decay constants, chiral perturbation theory calculations for the scalar form factor at the Callan-Treiman point and experimental information on the phase and modulus of $K\pi$ form factors up to an energy \tin=1 {\rm GeV}^2. We further derive regions on the real axis and in the complex-energy plane where the form factors cannot have zeros.Comment: 6 pages, 5 figures; Seminar given at DAE-BRNS Workshop on Hadron Physics Bhabha Atomic Research Centre, Mumbai, India October 31-November 4, 2011, submitted to Proceeding

On iterated translated points for contactomorphisms of R^{2n+1} and R^{2n} x S^1

A point q in a contact manifold is called a translated point for a contactomorphism \phi, with respect to some fixed contact form, if \phi (q) and q belong to the same Reeb orbit and the contact form is preserved at q. The problem of existence of translated points is related to the chord conjecture and to the problem of leafwise coisotropic intersections. In the case of a compactly supported contactomorphism of R^{2n+1} or R^{2n} x S^1 contact isotopic to the identity, existence of translated points follows immediately from Chekanov's theorem on critical points of quasi-functions and Bhupal's graph construction. In this article we prove that if \phi is positive then there are infinitely many non-trivial geometrically distinct iterated translated points, i.e. translated points of some iteration \phi^k. This result can be seen as a (partial) contact analogue of the result of Viterbo on existence of infinitely many iterated fixed points for compactly supported Hamiltonian symplectomorphisms of R^{2n}, and is obtained with generating functions techniques in the setting of arXiv:0901.3112.Comment: 10 pages, revised version. I removed the discussion on linear growth of iterated translated points, because it contained a mistake. To appear in the International Journal of Mathematic

Solvability of an Infinite System of Singular Integral Equations

2000 Mathematics Subject Classification: 45G15, 26A33, 32A55, 46E15.Schauder's fixed point theorem is used to establish an existence result for an infinite system of singular integral equations in the form: (1) xi(t) = ai(t)+ ∫t0 (t − s)− α (s, x1(s), x2(s), …) ds, where i = 1,2,…, α ∈ (0,1) and t ∈ I = [0,T]. The result obtained is applied to show the solvability of an infinite system of differential equation of fractional orders

Randomised comparison of oral ofloxacin alone with combination of parenteral antibiotics in neutropenic febrile patients

Prompt treatment with empirical antibiotics in neutropenic febrile patients reduces morbidity and mortality. Most patients have been treated with parenteral combination antibiotics, but newer antibiotics with broad-spectrum bactericidal activity have made monotherapy feasible. Ofloxacin, a broad-spectrum fluoroquinolone, has the additional advantage that bactericidal concentrations can be achieved with oral administration. We have compared ofloxacin as an oral single agent with standard parenteral combination antibiotics for the management of neutropenic febrile patients in a prospective, randomised trial. Patients with severe neutropenia (absolute neutrophil count less than or equal to 0.5 x 10(9)/l), fever above 38 degrees C, and ability to take drugs by mouth were eligible for the study. After initial investigations, 60 patients were randomly assigned to oral ofloxacin 400 mg twice daily and 62 to parenteral combination antibiotic therapy (amikacin 15 mg/kg daily, plus, at various times in the trial, carbenicillin, cloxacillin, or piperacillin). Patients were examined 72 h and 7 days after the start of treatment and when neutropenia resolved. 24 (40%) ofloxacin-treated and 26 (42%) combination-treated patients had pyrexia of unknown origin (PUO). In both treatment groups, the treatment success rate was higher for such patients than for those with clinically or microbiologically documented infections (92% vs 67% [p less than 0.05] for ofloxacin; 85% vs 64% for combination). There were no significant differences in success rates of ofloxacin and combination treatment for these subgroups or overall (77% vs 73%). Patients with neutropenia for less than 1 week had better responses to both treatments than patients with longer-lasting neutropenia. There were 4 (7%) deaths in the ofloxacin group and 6 (10%) in the combination group. Both regimens were well tolerated. We conclude that oral single-agent ofloxacin is as effective as parenteral combination antibiotic therapy in neutropenic febrile patients, especially those expected to have short durations of neutropenia

Theory of unitarity bounds and low energy form factors

We present a general formalism for deriving bounds on the shape parameters of the weak and electromagnetic form factors using as input correlators calculated from perturbative QCD, and exploiting analyticity and unitarity. The values resulting from the symmetries of QCD at low energies or from lattice calculations at special points inside the analyticity domain can beincluded in an exact way. We write down the general solution of the corresponding Meiman problem for an arbitrary number of interior constraints and the integral equations that allow one to include the phase of the form factor along a part of the unitarity cut. A formalism that includes the phase and some information on the modulus along a part of the cut is also given. For illustration we present constraints on the slope and curvature of the K_l3 scalar form factor and discuss our findings in some detail. The techniques are useful for checking the consistency of various inputs and for controlling the parameterizations of the form factors entering precision predictions in flavor physics.Comment: 11 pages latex using EPJ style files, 5 figures; v2 is version accepted by EPJA in Tools section; sentences and figures improve

Blockchain's adoption in IoT: The challenges, and a way forward

© 2018 Elsevier Ltd The underlying technology of Bitcoin is blockchain, which was initially designed for financial value transfer only. Nonetheless, due to its decentralized architecture, fault tolerance and cryptographic security benefits such as pseudonymous identities, data integrity and authentication, researchers and security analysts around the world are focusing on the blockchain to resolve security and privacy issues of IoT. However, presently, not much work has been done to assess blockchain's viability for IoT and the associated challenges. Hence, to arrive at intelligible conclusions, this paper carries out a systematic study of the peculiarities of the IoT environment including its security and performance requirements and progression in blockchain technologies. We have identified the gaps by mapping the security and performance benefits inferred by the blockchain technologies and some of the blockchain-based IoT applications against the IoT requirements. We also discovered some practical issues involved in the integration of IoT devices with the blockchain. In the end, we propose a way forward to resolve some of the significant challenges to the blockchain's adoption in IoT

Stringent constraints on the scalar K pi form factor from analyticity, unitarity and low-energy theorems

We investigate the scalar K pi form factor at low energies by the method of unitarity bounds adapted so as to include information on the phase and modulus along the elastic region of the unitarity cut. Using at input the values of the form factor at t=0 and the Callan-Treiman point, we obtain stringent constraints on the slope and curvature parameters of the Taylor expansion at the origin. Also, we predict a quite narrow range for the higher order ChPT corrections at the second Callan-Treiman point.Comment: 5 pages latex, uses EPJ style files, 3 figures, replaced with version accepted by EPJ

The (Z_2)^3 symmetry of the non-tri-bimaximal pattern for the neutrino mass matrix

In view of the recent neutrino oscillation data pointing to a non-vanishing value for the smallest mixing angle ($\theta_z$), we derive and find explicit realizations of the $(Z_2)^3$ flavor symmetry which characterizes, for the neutrino mass matrix, uniquely a variant of the tripartite form, originally conceived to lead to the tri-bimaximal mixing with $\theta_z=0$, so that to allow now for a non-tri-bimaximal pattern with non-zero $\theta_z$. We impose this flavor symmetry in a setting including the charged leptons and we see that it can make room, through higher order terms involving new SM-singlet scalars, for the mass hierarchy of charged leptons. Moreover, within type-I seesaw mechanism augmented with the flavor symmetry, certain patterns occurring in both the Dirac and the Majorana neutrino mass matrices can accommodate all types of mass hierarchies in the effective neutrino mass matrix, but no lepton/baryon asymmetry can be generated. Finally, we discuss how type-II seesaw mechanism, when supplemented with the flavor symmetry, could be used to interpret the observed baryon asymmetry through leptogenesis.Comment: 14 pages, 1 table, added references, version to appear in PRD. arXiv admin note: text overlap with arXiv:1008.406