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We investigate photon emission at the hadronization stage from a quark-gluon plasma created in relativistic heavy-ion collisions. A recombination-model picture suggests that a quark and an antiquark bind into a meson state in hadronization,…

Nuclear Theory · Physics 2022-10-05 Hirotsugu Fujii , Kazunori Itakura , Katsunori Miyachi , Chiho Nonaka

We identify an accretion disk atmosphere and corona from the high resolution X-ray spectrum of Hercules X-1, and we determine its detailed physical properties. More than two dozen recombination emission lines (from Fe XXVI at 1.78 A to N VI…

The Dirac equation for H$_2^+$ is solved numerically using an iterative method proposed by Kutzelnigg [Z. Phys. 11, 15 (1989]. The four-component wavefunction is expanded in a newly introduced kinetically balanced exponential basis set. The…

Atomic Physics · Physics 2022-06-15 Hugo D. Nogueira , Vladimir I. Korobov , Jean-Philippe Karr

Radiation from stars and AGN plays an important role in galaxy formation and evolution, and profoundly transforms the IGM, CGM & ISM. On-the-fly RT has started being incorporated in cosmological simulations, but the complex, evolving…

Astrophysics of Galaxies · Physics 2024-11-20 Bernhard Baumschlager , Sijing Shen , James W. Wadsley

Precise spectral diagnostic modelling of H~{\sc i} and He~{\sc ii} recombination spectra can constrain theoretical models which describe many astrophysical environments. Simple analytic expressions are of interest for collisional…

Solar and Stellar Astrophysics · Physics 2021-09-15 N. R. Badnell , F. Guzmán , S. Brodie , R. J. R. Williams , P. A. M. van Hoof , M. Chatzikos , G. J. Ferland

It is shown that above the temperature of maximum abundance, recombination rates into the excited states of He-like ions that are calculated using earlier, more approximate methods differ markedly from rates obtained from recent…

Astrophysics · Physics 2007-11-26 J. Oelgoetz , C. J. Fontes , H. L. Zhang , M. Montenegro , S. N. Nahar , A. K. Pradhan

We discuss a concept of a lower-energy version of the Large Hadron-electron Collider (LHeC), delivering electron-hadron collisions concurrently to the hadron-hadron collisions at the high-luminosity LHC at CERN. Assuming the use of a 20 GeV…

High Energy Physics - Experiment · Physics 2026-05-05 Kevin David J André , Laurent Forthomme , Bernhard Holzer , Krzysztof Piotrzkowski

We present near-infrared spectroscopic observations of the high-intensity HeI 10830 emission line in 45 low-metallicity HII regions. We combined these NIR data with spectroscopic data in the optical range to derive the primordial He…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-03 Y. I. Izotov , T. X. Thuan , N. G. Guseva

Using state-of-the-art ab initio interaction-induced dipole and potential-energy surfaces for hydrogen-helium (H2-He) pairs, we compute the rototranslational collision-induced absorption coefficient at 40-400 K for frequencies covering…

Earth and Planetary Astrophysics · Physics 2025-06-12 Glenn S. Orton , Magnus Gustafsson , Leigh N. Fletcher , Michael T. Roman , James A. Sinclair

We estimate the nuclear polarizability correction to atomic transition frequencies in various helium isotopes. This effect is non-negligible for high precision tests of quantum electrodynamics or accurate determination of the nuclear charge…

Nuclear Theory · Physics 2015-06-26 K. Pachucki , A. M. Moro

The inverse processes of photoionization and electron-ion recombination of (hnu + Ni XXVI --> Ni XXVII + e and (hnu + Ni XXVII --> Ni XXVIII + e) are studied using the unified method for the total recombination. The method subsumes both the…

Astrophysics · Physics 2009-11-10 Sultana N. Nahar

The possible use of high-resolution rovibrational spectroscopy of the hydrogen molecular ions H + 2 and HD + for an independent determination of several fundamental constants is analyzed. While these molecules had been proposed for…

Atomic Physics · Physics 2017-02-20 J. -Ph Karr , L Hilico , Jeroen Koelemeij , Vladimir Korobov

Resonant nuclear reactions are a powerful tool for the determination of the amount and profile of hydrogen in thin layers of material. Usually, this tool requires the use of a standard of well-known composition. The present work, by…

Nuclear Experiment · Physics 2016-06-03 Tobias P. Reinhardt , Shavkat Akhmadaliev , Daniel Bemmerer , Klaus Stöckel , Louis Wagner

Hierarchical forecasting with reconciliation requires forecasting values of a hierarchy (e.g.~customer demand in a state and district), such that forecast values are linked (e.g.~ district forecasts should add up to the state forecast).…

Machine Learning · Computer Science 2025-05-09 Charupriya Sharma , Iñaki Estella Aguerri , Daniel Guimarans

We present calculations of the electron angular distributions in the single ionization of helium by 1-MeV proton impact at momentum transfer of 0.75 a.u. and ejected-electron energy of 6.5 eV. The results using the first and second Born…

Atomic Physics · Physics 2017-11-02 O. Chuluunbaatar , S. A. Zaytsev , K. A. Kouzakov , A. Galstyan , V. L. Shablov , Yu. V. Popov

We present an extension of the recombination formalism to analyze the effects from the variation of the hadron wavefunctions. The hadron spectra are sensitive to the shape of the wavefunctions. However, when we fit the wavefunction…

High Energy Physics - Phenomenology · Physics 2009-09-29 Byungsik Hong , Chueng-Ryong Ji , Dong-Pil Min

We review the current status of recombination and coalescence models that have been successfully applied to describe hadronization in heavy ion collisions at RHIC energies. Basic concepts as well as actual implementations of the idea are…

Nuclear Theory · Physics 2009-11-10 R. J. Fries

A simultaneous description of hadronic yields; pion, kaon, and proton spectra; elliptic flows; and femtoscopy scales in the hydrokinetic model of A+A collisions is presented at different centralities for the top BNL Relativistic Heavy Ion…

Nuclear Theory · Physics 2013-03-14 Iu. A. Karpenko , Yu. M. Sinyukov , K. Werner

The recombination of hydrogen in the interstellar medium, taking place on surfaces of microscopic dust grains, is an essential process in the evolution of chemical complexity in interstellar clouds. The H_2 formation process has been…

Condensed Matter · Physics 2009-11-07 Ofer Biham , Azi Lipshtat

We describe experiments where 2D atomic hydrogen gas is compressed thermally at a small "cold spot" on the surface of superfluid helium and detected directly with electron-spin resonance. We reach surface densities up to 5e12 1/cm^2 at…

Soft Condensed Matter · Physics 2009-11-10 S. Vasilyev , J. Jarvinen , A. I. Safonov , S. Jaakkola