Article
Astronomy & Astrophysics
Dong-Lin Wang, Shuo Fang, Shi Pu
Summary: By studying analytically the longitudinally boost-invariant motion of a relativistic dissipative fluid with spin, we have derived analytic solutions for spin density and spin chemical potential as functions of proper time tau, showing that they decay at rates similar to tau-1 and tau-1/3, respectively. These solutions provide insights into spin polarization dynamics in relativistic heavy-ion collisions and serve as test beds for further numerical simulations.
Article
Physics, Particles & Fields
S. Godunov, E. K. Karkaryan, V. A. Novikov, A. N. Rozanov, M. Vysotsky, E. Zhemchugov
Summary: Analytical formulas for the cross section of the reaction pp -> p + l(+ )l(-) + X are presented and compared with the fiducial cross sections measured recently by the ATLAS collaboration.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Multidisciplinary
Ijaz Ahmed, Anwar Zada, Muhammad Waqas, M. U. Ashraf
Summary: This article demonstrates the performance of an efficient top tagger for hadronically decaying boosted top quark pairs using deep neural network algorithms and Lorentz Layer with the Minkowskimetric. Due to limited computing resources, the analysis shows the receiver operating characteristic curve, accuracy, and loss, highlighting the trade-off between signal acceptance and QCD multi-jet background acceptance. In addition, modern machine learning techniques such as boosted decision tree (BDT), likelihood, and multilayer perceptron (MLP) are used to observe the observability of single top quark production through weak interaction against relevant Standard Model backgrounds, comparing their performance with conventional cut based and counting approaches.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Physics, Particles & Fields
Captain R. Singh, Suman Deb, Raghunath Sahoo, Jan-e Alam
Summary: In this study, the suppression of charmonium in pp collisions is investigated, and the possibility of quark-gluon plasma formation in high-multiplicity events is indicated.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Ren-jie Wang, Shuo Lin, Shi Pu, Yi-fei Zhang, Qun Wang
Summary: In this study, we investigated the lepton pair photoproduction in peripheral heavy-ion collisions, focusing on the distribution of transverse momentum, azimuthal angle, and invariant mass for e+e- and mu+mu- pairs in Au + Au collisions. Our calculations included information on photon transverse momentum and polarization, leading to a better description of experimental data. The results indicated a broadening effect in transverse momentum for lepton pairs and a significant enhancement in the distribution of cos(2v) for mu+mu- pairs.
Article
Astronomy & Astrophysics
Dong-Lin Wang, Xin-Qing Xie, Shuo Fang, Shi Pu
Summary: The researchers have derived the analytic solutions of dissipative relativistic spin hydrodynamics with Gubser expansion, which can be used as test beds for future simulations.
Article
Physics, Particles & Fields
Liang Zhang, Song Zhang, Yu-Gang Ma
Summary: This study calculates the interactions, binding energies, and production rates of Omega N and Omega Omega in multi-strangeness hypernuclei using simulations. It also discusses the production and decay channels of more exotic triple-baryons and predicts the production rate of a more exotic tetra-baryon.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Laura Duarte, Victor P. Goncalves, Daniel E. Martins, Tessio B. de Melo, Farinaldo S. Queiroz
Summary: This paper investigates the possibility of searching for the doubly charged Higgs boson (H +/-+/-) in exclusive processes, characterized by two rapidity gaps and two intact very forward protons in the final state. The associated cross section is estimated using the exclusive nature of the final state and timing information provided by forward proton detectors. Background estimation and pileup effects are also considered. The results suggest that exclusive doubly charged Higgs pair production is a promising way to search for signatures of the type II seesaw mechanism and obtain lower mass bounds on H +/-+/−.
Article
Physics, Nuclear
G. Coci, S. Glassel, V. Kireyeu, J. Aichelin, C. Blume, E. Bratkovskaya, V. Kolesnikov, V. Voronyuk
Summary: This study investigates the dynamical formation of deuterons in heavy-ion collisions using the parton-hadron quantum molecular dynamics (PHQMD) microscopic transport approach. Two microscopic production mechanisms, kinetic production by hadronic reactions and potential production by the attractive potential between nucleons, are advanced to describe deuterons. The study finds that considering the quantum nature of deuterons reduces substantially the kinetic deuteron production in heavy-ion collisions.
Article
Astronomy & Astrophysics
Ren-jie Wang, Shuo Lin, Shi Pu, Yi-fei Zhang, Qun Wang
Summary: In this study, we investigate the lepton pair photoproduction in peripheral heavy-ion collisions. Numerical results are presented for the distributions of the transverse momentum, azimuthal angle, and invariant mass of e(+)e(-) and mu(+)mu(-) pairs in Au + Au collisions as functions of the impact parameter and other kinematic variables. Our calculation takes into account the information on the transverse momentum and polarization of photons, which are crucial for describing the experimental data. The results show a broadening effect in the transverse momentum of lepton pairs with and without smear effects, as well as a significant enhancement in the distribution of cos(2 phi) for mu(+)mu(-) pairs. These findings serve as a baseline for future studies on higher order corrections and medium effects in lepton pair production.
Article
Physics, Multidisciplinary
Nadia Kausar, Ijaz Ahmed, M. W. Ather
Summary: The observability of charged Higgs bosons in the I type 2HDM model has been investigated at a future lepton collider. Events are analyzed to reconstruct the mass of the charged Higgs bosons, and signal selection and significance efficiencies are calculated. The results show that charged Higgs bosons can be discovered through the bosonic decay process.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Multidisciplinary
Michal Czakon, Alexander Mitov, Rene Poncelet
Summary: This study utilizes multijet rates to explore quantum chromodynamics (QCD), calculating NNLO QCD corrections for three-jet observables and three-to-two jet ratios. It demonstrates a significant reduction in the dependence of these observables on factorization and renormalization scales. This proof-of-principle computation represents a milestone in perturbative QCD.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Daniel E. Martins, Marek Tasevsky, Victor P. Goncalves
Summary: The study investigates the elastic production of top quark pairs in pp collisions at low and high luminosity regimes, with a focus on separating different production modes and the challenges of separation at high levels of pile-up compared to low levels.
Article
Astronomy & Astrophysics
Ilkka Helenius, Marina Walt, Werner Vogelsang
Summary: New nuclear parton distribution functions (nPDFs) are presented at next-to-leading order and next-to-next-to-leading order in perturbative QCD, based on a combination of deeply inelastic scattering data and experimental data from LHC collisions. The analysis includes fitting a set of proton baseline PDFs within the same framework. Results show good agreement with the included data and lower chi(2)/N-dp value at next-to-next-to-leading order. Application of the nuclear PDFs to electroweak boson production in LHC Pb + Pb collisions is compared to recent ATLAS and CMS data.
Article
Astronomy & Astrophysics
A. H. Ajjath, Benjamin Fuks, Hua-Sheng Shao, Yehudi Simon
Summary: This study calculates the total and differential cross sections for the pair production of exotic leptons that could exist in models with vectorlike leptons and in type-III seesaw scenarios at the Large Hadron Collider. The predictions take into account next-to-leading-order QCD corrections and are matched with either parton showers or threshold resummation at the next-to-next-to-leading logarithmic accuracy. The results show an important increase in the cross sections, distortion of the shapes for various differential distributions, and a significant reduction of the scale uncertainties. These predictions are obtained using new FeynRules model implementations and associated Universal FeynRules Output model libraries, completing the set of publicly available next-to-leading-order implementations of new physics models featuring extra leptons in the FeynRules model database.
Article
Physics, Nuclear
W. Noertershaeuser, A. Surzhykov, R. Sanchez, B. Botermann, G. Gwinner, G. Huber, S. Karpuk, T. Kuehl, C. Novotny, S. Reinhardt, G. Saathoff, T. Stoehlker, A. Wolf
Summary: The study found that using circularly polarized light leads to a disappearance of the resonance structure in the fluorescence signal, possibly due to optical pumping into a dark state of polarized ions. A detailed theoretical analysis of this process supports the interpretation of optical pumping and demonstrates that the polarization induced by the laser light must be at least partially maintained during the round trip of the ions in the storage ring.
PHYSICAL REVIEW ACCELERATORS AND BEAMS
(2021)
Article
Biochemistry & Molecular Biology
Stephan Fritzsche, Andrey Surzhykov
Summary: This paper demonstrates how relativistic (many-electron) Green functions can be approximated and systematically improved for few- and many-electron atoms and ions by utilizing classes of virtual excitations and a multi-configuration Dirac-Hartree-Fock expansion. The implementation of these approximate Green functions in the Jena Atomic Calculator will facilitate the study of various multi-photon and multiple electron processes.
Article
Physics, Multidisciplinary
Valeriy G. Serbo, Andrey Surzhykov, Andrey Volotka
Summary: This theoretical investigation focuses on the resonant elastic scattering of laser photons by ultra-relativistic partially stripped ions, emphasizing the angular distribution and polarization of scattered photons in different reference frames. The general approach, based on irreducible polarization tensors, is utilized to describe these properties for relativistic many-electron ions, exploring both conventional and twisted photons. The study demonstrates the relationship between incident and outgoing photon propagation directions and polarization states for specific resonant transitions, as well as the angular distribution of secondary photons in the scattering of initially twisted light carrying orbital angular momentum.
ANNALEN DER PHYSIK
(2022)
Article
Physics, Multidisciplinary
Jan Richter, Anna Maiorova, Anna V. Viatkina, Dmitry Budker, Andrey Surzhykov
Summary: In this theoretical study, the process of photoexcitation of highly charged ions from their ground states is investigated, with a focus on the effects of mixing of opposite-parity ionic levels induced by external electric fields and weak electron-nucleus interactions. Relativistic Dirac theory is employed to study the Stark-plus-weak-interaction mixing, and detailed calculations are performed for specific transitions in hydrogen-like and lithium-like ions. The importance of circular dichroism measurements with highly charged ions in understanding the electron-nucleus weak-interaction coupling is highlighted.
ANNALEN DER PHYSIK
(2022)
Article
Physics, Multidisciplinary
Andrey Volotka, Dmitrii Samoilenko, Stephan Fritzsche, Valeriy G. Serbo, Andrey Surzhykov
Summary: This theoretical investigation focuses on the elastic resonant scattering of photons by ultra-relativistic and partially stripped ions. The study pays particular attention to the angular distribution and polarization of scattered photons from both the ion-rest and laboratory reference frames. The results show that the resonantly scattered photons can be strongly polarized and this polarization can be controlled by adjusting the emission angle and/or the polarization state of the incident radiation. The potential of photon scattering for measuring the spin-polarization of ion beams is also discussed.
ANNALEN DER PHYSIK
(2022)
Article
Physics, Atomic, Molecular & Chemical
Sophia Strnat, Jonas Sommerfeldt, Vladimir Yerokhin, Wilko Middents, Thomas Stoehlker, Andrey Surzhykov
Summary: This article presents a theoretical investigation on the elastic Rayleigh scattering of X-rays by atomic targets. The authors focus on the polarization of the scattered photons when the incident light is polarized. They found that the circular polarization of the incoming X-rays can modify the linear polarization of the scattered photons. Based on this finding, they propose the use of Rayleigh scattering as a tool for circular polarimetry of hard X-rays and provide detailed calculations and discussions to support their proposal.
Article
Chemistry, Physical
Anton N. Artemyev, Eric Kutscher, Boris M. Lagutin, Philipp V. Demekhin
Summary: The spin polarization of 5p(3/2)- and 5p(1/2)-electrons in Xe under intense 395nm circularly polarized laser pulses during multiphoton above-threshold ionization is theoretically investigated. The time-dependent Schrodinger equation is solved using spherical spinors to simultaneously propagate the spin-up and spin-down single-active-electron wave packets, considering the spin-orbit interaction explicitly in the ionic potential. The theoretical results agree well with recent experimental results.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
Anton A. Peshkov, Elena Jordan, Markus Kromrey, Karan K. Mehta, Tanja E. Mehlstaeubler, Andrey Surzhykov
Summary: In this study, the photoexcitation of trapped ions by Hermite-Gaussian (HG) modes from guided beam structures is proposed and theoretically investigated. Simple analytical expressions for the matrix elements of induced atomic transitions are derived, which depend on both the parameters of HG beams and the geometry of the experiment. The study focuses on the investigation of the 2S1/2 & RARR;2F7/2 electric octupole (E3) transition in an Yb+ ion localized in the low-intensity center of the HG(10) and HG(01) beams. The results suggest that HG-like modes could serve as a novel tool for investigating highly-forbidden atomic transitions, as they can be generated with high purity and stability from integrated photonics.
ANNALEN DER PHYSIK
(2023)
Article
Physics, Multidisciplinary
J. Sommerfeldt, V. A. Yerokhin, Th. Stoehlker, A. Surzhykov
Summary: We present calculations of Delbruck scattering with all-order Coulomb corrections for photon energies above the electron-positron pair creation threshold. Our method utilizes the Dirac-Coulomb Green's function and accounts for the interaction between the virtual electron-positron pair and the nucleus to all orders in the nuclear binding strength parameter αZ. Practical calculations are performed for 2.754 MeV photon scattering off plutonium atoms. Our results show that including the Coulomb corrections increases the scattering cross section by up to 50% in this case, resolving the long-standing discrepancy between experimental data and theoretical predictions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Optics
O. Novak, R. Kholodov, A. N. Artemyev, A. Surzhykov, Th. Stoehlker
Summary: The ionization of a hydrogenlike heavy ion by the impact of a charged projectile under simultaneous irradiation by a short laser pulse is studied using the nonperturbative approach. Numerical solutions of the time-dependent Dirac equation were used for detailed calculations, focusing on the interference between the laser-and impact-ionization channels and its effect on ionization probability. The results demonstrate that the interference contribution can reach 10% for experimentally relevant parameters and can be controlled by varying the laser frequency.
Article
Physics, Multidisciplinary
Junlan Jin, Hendrik Bekker, Tobias Kirschbaum, Yuri A. Litvinov, Adriana Palffy, Jonas Sommerfeldt, Andrey Surzhykov, Peter G. Thirolf, Dmitry Budker
Summary: 229Th with a low-lying nuclear isomeric state is a promising candidate for a nuclear clock and other applications. Laser excitation of the isomeric state can be achieved through direct resonant excitation or via intermediate states. The unique opportunities offered by highly charged 229Th ions and their significantly reduced isomeric-state lifetime make it possible to achieve high excitation rates. We propose electric dipole transitions and suggest using them for efficient isomer excitation in Li-like 229Th ions, as well as schemes for probing the isomers and determining their energy with higher precision.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Optics
Anna V. Maiorova, Stephan Fritzsche, Andrey Surzhykov, Thomas Stoehlker
Summary: We theoretically investigate the radiative recombination of heavy highly charged ions with polarized electrons. Our results show that the linear polarization of emitted photons is highly sensitive to the spin state of the incident electrons, which can be easily observed using modern Compton polarization detectors.
Article
Optics
A. A. Peshkov, Y. M. Bidasyuk, R. Lange, N. Huntemann, E. Peik, A. Surzhykov
Summary: We have conducted a theoretical study on the nondipole excitation of a single trapped atom by twisted light, with a focus on the interplay between the internal and vibrational degrees of freedom of an atom. By using the density-matrix approach based on the Liouville-von Neumann equation, we obtained a quantum mechanical understanding of the excitation process. Our theory was applied to the 4s 2S1/2 -> 3d 2D5/2 electric quadrupole (E2) transition in a 40Ca+ ion induced by Laguerre-Gaussian modes, revealing unconventional anharmonic Rabi oscillations attributed to the strong coupling between vibrational levels of the trap.
Article
Optics
A. N. Artemyev, A. Surzhykov, V. A. Yerokhin
Summary: We present a theoretical approach for calculating the one-loop QED corrections to energy levels of heavy diatomic quasimolecules from first principles. The method utilizes the partial-wave expansion and monopole solutions in spherical coordinates to evaluate self-energy and vacuum-polarization corrections. Detailed calculations are performed for the Dirac energy and QED corrections of specific quasimolecules to illustrate the application of the method.
Article
Optics
J. Sommerfeldt, V. A. Yerokhin, R. A. Mueller, V. A. Zaytsev, A. V. Volotka, A. Surzhykov
Summary: We present a theoretical method to calculate Delbruck scattering amplitudes, which is based on the exact analytical Dirac-Coulomb Green's function and takes into account the interaction of the virtual electron-positron pair with the nucleus to all orders, including the Coulomb corrections. Our method accelerates the numerical convergence by solving the radial integrals analytically. Numerical results reveal that our method can produce accurate results within a reasonable computation time and that the Coulomb corrections enhance the absolute value of the Delbruck amplitude by a few percent for the studied photon energies.
