Baryon stopping and saturation physics in relativistic collisions

We investigate baryon transport in relativistic heavy-ion collisions at energies reached at the CERN Super Proton Synchrotron, BNL Relativistic Heavy-Ion Collider (RHIC), and CERN LHC in the model of saturation. An analytical scaling law is derived within the color glass condensate framework based on small-coupling QCD. Transverse momentum spectra, net-baryon rapidity distributions and their energy, mass and centrality dependences are well described. In a comparison with RHIC data in Au + Au collisions at sqrt (s_NN) = 62.4 GeV and 200 GeV, the gradual approach to the gluon saturation regime is investigated, and limits for the saturation-scale exponent are determined. Predictions for net-baryon rapidity spectra and the mean rapidity loss in central Pb + Pb collisions at LHC energies of sqrt (s_NN) = 5.52 TeV are made.Comment: 11 pages, 10 Figures; improved figure inscriptions, corrected typos, minor changes in text/titl

Signatures of axion-like particles in the spectra of TeV gamma-ray sources

One interpretation of the unexplained signature observed in the PVLAS experiment invokes a new axion-like particle (ALP) with a two-photon vertex, allowing for photon-ALP oscillations in the presence of magnetic fields. In the range of masses and couplings suggested by PVLAS, the same effect would lead to a peculiar dimming of high-energy photon sources. For typical parameters of the turbulent magnetic field in the galaxy, the effect sets in at E_gamma >~ 10 TeV, providing an ALP signature in the spectra of TeV gamma sources that can be probed with Cherenkov telescopes. A dedicated search will be strongly motivated if the ongoing photon regeneration experiments confirm the PVLAS particle interpretation.Comment: 8 pages, 1 eps figure; typos corrected, matches published versio

Baryon Stopping as a new Probe of Geometric Scaling

We suggest to use net-baryon rapidity distributions in central relativistic heavy-ion collisions at SPS, RHIC and LHC energies in order to probe saturation physics. Within the color glass condensate framework based on small-coupling QCD, net-baryon rapidity distributions are shown to exhibit geometric scaling. In a comparison with RHIC data in Au + Au collisions at sqrt(s_NN) = 62.4 GeV and 200 GeV the gradual approach to the gluon saturation regime is investigated. Predictions for net-baryon rapidity spectra and the mean rapidity loss in central Pb + Pb collisions at LHC energies of sqrt (s_NN) = 5.5 TeV are made.Comment: 4 pages 3 figures; calculation and figures now for net baryons instead of net protons; modified conclusion

Quantum Continuum Mechanics Made Simple

In this paper we further explore and develop the quantum continuum mechanics (CM) of [Tao \emph{et al}, PRL{\bf 103},086401] with the aim of making it simpler to use in practice. Our simplifications relate to the non-interacting part of the CM equations, and primarily refer to practical implementations in which the groundstate stress tensor is approximated by its Kohn-Sham version. We use the simplified approach to directly prove the exactness of CM for one-electron systems via an orthonormal formulation. This proof sheds light on certain physical considerations contained in the CM theory and their implication on CM-based approximations. The one-electron proof then motivates an approximation to the CM (exact under certain conditions) expanded on the wavefunctions of the Kohn-Sham (KS) equations. Particular attention is paid to the relationships between transitions from occupied to unoccupied KS orbitals and their approximations under the CM. We also demonstrate the simplified CM semi-analytically on an example system

On the Validity of the 0-1 Test for Chaos

In this paper, we present a theoretical justification of the 0-1 test for chaos. In particular, we show that with probability one, the test yields 0 for periodic and quasiperiodic dynamics, and 1 for sufficiently chaotic dynamics

Regioselective C5-alkylation and C5-methylcarbamate formation of 2,3-dihydro-4-pyridones and C3-alkylation and C3-methylcarbamate formation of 4-(pyrrolidin-1-yl)furan-2(5H)-one

Reactions of N-alkyl-2,3-dihydro-4-pyridones and 4-(pyrrolidin-1-yl)furan-2(5H)-one with aldehydes and triethylsilane in a one-flask procedure provided C5 and C3 alkylated derivatives, respectively. Mannich-type reactions with formaldehyde and carbamates in the presence of lithium perchlorate furnished C5/C3 methylcarbamates

Regioselective C5-alkylation and C5-methylcarbamate formation of 2,3-dihydro-4-pyridones and C3-alkylation and C3-methylcarbamate formation of 4-(pyrrolidin-1-yl)furan-2(5H)-one

Reactions of N-alkyl-2,3-dihydro-4-pyridones and 4-(pyrrolidin-1-yl)furan-2(5H)-one with aldehydes and triethylsilane in a one-flask procedure provided C5 and C3 alkylated derivatives, respectively. Mannich-type reactions with formaldehyde and carbamates in the presence of lithium perchlorate furnished C5/C3 methylcarbamates

Direct Hiyama Cross-Coupling of Enaminones With Triethoxy(aryl)silanes and Dimethylphenylsilanol

2,3-Dihydropyridin-4(1H)-ones undergo direct C–H functionalization at C5 in the palladium(II)-catalyzed Hiyama reaction, using triethoxy(aryl)silanes and dimethylphenylsilanol. The reagent CuF2 has a dual role in the reactions with triethoxy(aryl)silanes. It is a source of fluoride to activate the silane in the Hiyama reaction and also serves as the reoxidant to convert Pd(0) to Pd(II) in the catalytic cycle

Total Syntheses of Arylindolizidine Alkaloids (+)-Ipalbidine and (+)-Antofine

This paper presents the first application of two recently developed reactions to natural product synthesis. The first method involves a 6-endo-trig cyclization to prepare a versatile chiral enaminone building block. The second is a direct C–H arylation reaction. As a showcase for the utility of these methods, (+)-antofine and (+)-ipalbidine were synthesized in only 8 steps and 24–26% overall yields