Fall and rise of the gluon splitting function

This talk reviews some recent results on the NLL resummed small-x gluon splitting function, as determined including renormalisation-group improvements. It also discusses the observation that the LO, NLO, NNLO, etc. hierarchy for the gluon splitting function breaks down not when (alpha_s log 1/x) is of order one but rather for (alpha_s log^2 1/x) of order one.Comment: 7 pages, 3 figures; Talk presented at DIS 2004, Strbske Pleso, Slovakia, April 2004, and at the Eighth Workshop on Non-Perturbative Quantum Chromodynamics, Paris, France, June 200

Field Redefinition Invariance in Quantum Field Theory

The issue of field redefinition invariance of path integrals in quantum field theory is reexamined. A ``paradox'' is presented involving the reduction to an effective quantum-mechanical theory of a $(d+1)$-dimensional free scalar field in a Minkowskian spacetime with compactified spatial coordinates. The implementation of field redefinitions both before and after the reduction suggests that operator-ordering issues in quantum field theory should not be ignored.Comment: 7 page

An on-line harmonics elimination PWM scheme for three-phase voltage source inverters

An on-line harmonic elimination PWM (HEPWM) scheme for three-phase voltage source inverters is proposed. It is based on curve fitting method derived from the trajectories of the exact (off-line) HEPWM angles. The main advantage of the technique is its fast and efficient realization using a microprocessor. An outline to obtain the switching angles is presented. The method is proven by experimental result

Casimir-Polder intermolecular forces in minimal length theories

Generalized uncertainty relations are known to provide a minimal length $\hbar\sqrt{\beta}$. The effect of such minimal length in the Casimir-Polder interactions between neutral atoms (molecules) is studied. The first order correction term in the minimal uncertainty parameter is derived and found to describe an attractive potential scaling as $r^{-9}$ as opposed to the well known $r^{-7}$ long range retarded potential.Comment: 1 Figure. Version published by Physical Review D. Few references added, typos correcte

A note on the CDF high-p_t charged particle excess

It has recently been pointed out that CDF data for the cross section of high-p_t charged particles show an excess of up to three orders of magnitude over QCD predictions, a feature tentatively ascribed to possible violations of factorisation. We observe that for p_t > 80 GeV the measured charged-particle cross sections become of the same order as jet cross sections. Combining this information with data on charged particle distributions within jets allows us to rule out the hypothesis that the CDF data could be interpreted in terms of QCD factorisation violation. We also comment on the difficulty of interpreting the excess in terms of new physics scenarios.Comment: 8 pages, 4 figure

Energy Correlation Functions for Jet Substructure

We show how generalized energy correlation functions can be used as a powerful probe of jet substructure. These correlation functions are based on the energies and pair-wise angles of particles within a jet, with (N+1)-point correlators sensitive to N-prong substructure. Unlike many previous jet substructure methods, these correlation functions do not require the explicit identification of subjet regions. In addition, the correlation functions are better probes of certain soft and collinear features that are masked by other methods. We present three Monte Carlo case studies to illustrate the utility of these observables: 2-point correlators for quark/gluon discrimination, 3-point correlators for boosted W/Z/Higgs boson identification, and 4-point correlators for boosted top quark identification. For quark/gluon discrimination, the 2-point correlator is particularly powerful, as can be understood via a next-to-leading logarithmic calculation. For boosted 2-prong resonances the benefit depends on the mass of the resonance.Comment: 45 pages, 28 figures, update to JHEP version, some minor typos fixed, added discussion at end of section

Estimates of Radiation by Superluminal Neutrinos

We show that the more energetic superluminal neutrinos with quadratically dispersed superluminalities \delta=\beta^2-1, for \beta=v/c where v is the neutrino velocity, also lose significant energy to radiation to the \nu+e^-+e^+ final state in travelling from CERN to Gran Sasso as has been shown to occur for those with constant superluminality by Cohen and Glashow if indeed \delta \simeq 5\times 10^{-5}. In addition, we clarify the dependence of such radiative processes on the size of the superluminality.Comment: 6 pages, no figures; text re-arranged for journal purposes; improved references; published version(title changed by Editors

Tinjauan Estetika Foto Hitam Putih pada Fotografi Lansekap Karya Hengky Koentjoro

Kemampuan seseorang dalam apresiasi foto menjadi lebih baik bila menguasai banyak aspek teknis dan non-teknis fotografi. Sisi artistik saja belum cukup kuat untuk membuat foto tersebut menjadi menarik. Tanpa kemampuan teknis, seorang fotografer menghasilkan foto tanpa kualitas maksimal. Sebaliknya, tanpa sentuhan seni, foto yang dihasilkan tentu tanpa rasa. Kekuatan sebuah foto dibangun oleh sejumlah unsur, yakni, pilihan objek, cahaya, komposisi, angle dan momen. Fotografer perlu untuk mengkaji obyek, menyeleksi, memilih dengan mendekatkan atau menjauh, mencari posisi untuk mendapatkan angle yang baik serta menunggu momen. Obyek studi penulisan ini adalah karya fotografi fine art karya Hengki Koentjoro dengan teknik long exposure. Secara umum, fine art photography didefinisikan sebagai gabungan karya seni dan fotogarafi yang dilakukan dengan kecermatan, ketelitian, presisi, dan perhitungan matang. Dimulai dari ide, konsep, pra-visualisasi, pengambilan gambar, penerapan teknik, termasuk keahlian mencetak gambar. Teknik long exsposure mengacu pada shutter speed yang lama, yakni teknik khusus untuk mengambil foto dengan membuka shutter kamera untuk waktu yang lama. Hal ini memungkinkan lebih banyak cahaya memasuki kamera sampai shutter tertutup. Secara teknis, kamera membaca lebih banyak data dari subjek, mengumpulkan detail-detail, dan menciptakan efek blurring pada subjek yang bergerak. Ada banyak cara membuat efek blurring yang dapat digambarkan dalam fotografi, hanya praktek dan eksperimentasi yang memungkinkan untuk memahami dan memprediksi efek long exposure dalam kaitannya dengan waktu dan gerak

Internal conversions in Higgs decays to two photons

We evaluate the partial widths for internal conversions in the Higgs decays to two photons. For the Higgs masses of interest at LHC in the range of 100-150 GeV, the conversions to pairs of fermions represent significant fraction of Higgs decays.Comment: one .tex file and two .eps figure