1s State Research Articles

BEEC2.0: An upgraded version for the production of heavy quarkonium at electron-positron collider

The event generator BEEC (Yang et al. (2013) [11]) was devoted to the simulation of heavy quarkonium production at an unpolarized electron-positron collider. We upgraded it here by adding the generation of quarkonium with polarized electron and positron beams. In addition, the production of color-singlet 2S-wave states were included. Several future electron-positron colliders with high luminosity have been under discussion in the past decade. Especially, their possibility of producing polarized beams is important for providing more insights into the underlying physics. This upgraded version offers a useful tool for the feasibility study on quarkonium from the experimental side. New version program summaryProgram title: BEEC version 2.0CPC Library link to program files:https://doi.org/10.17632/bvtwwm22tj.1Licensing provisions: GNU General Public License 3Programming language: FORTRAN 77/90Journal Reference of previous version: Comput. Phys. Commun. 184 (2013) 2848Does the new version supersede the previous version?: YesReasons for the new version: The proposed electron-positron colliders could possibly produce polarized beams, with which it would be helpful to provide more insights into the structure of the underlying physics in heavy quarkonium. Thus, it is essential to simulate the quarkonium production through polarized beams. In addition, the Bc(2S) state attracted more and more interests since its discovery, which makes it necessary to produce the 2S-wave excited states.Summary of revisions: Two polarized amplitudes of leptonic scattering are computed theoretically. The relevant codes of the formula are included in BEEC2.0. Meanwhile, new parameters for the 2S-excited states are also included.Nature of problem: Although PYTHIA can generate events for many processes, a dedicated event generator is also necessary. Especially, PYTHIA does not internally produce events with polarized beams. BEEC is implemented into PYTHIA as an external process for simulating heavy quarkonium events with high efficiency. Further hadronization and decay simulation can be done by using PYTHIA subroutine.Solution method: Two projection operators are used to calculate the polarized leptonic scattering amplitudes with the help of improved trace technology [1,2]. The code with option can generate events through unpolarized and polarized initial beams. In addition to the (QQ′¯)-quarkonium (Q,Q′=b,c) in color-singlet 1S-wave states, 1P-wave states, and the color-octet 1S-wave states in the last version, BEEC 2.0 also deal with the production of 2S-wave excited states within the framework of non-relativistic QCD [3].Additional comments including restrictions and unusual features: About the running time, it depends on which option one chooses to match PYTHIA when generating the heavy quarkonium events. Typically, for the production of the S-wave quarkonium states, if setting IDWTUP=1 (unweighted events), then it takes about 21 minutes on a 3.22 GHz Apple M1 Pro Processor machine to generate 105 events; if setting IDWTUP=3 (weighted events), it takes only ∼5 minutes to generate 105 events. While for the production of the P-wave quarkonium states, the time will be almost one hundred times longer than the case of the S-wave quarkonium.

Masses and thermal properties of a Charmonium and Bottomonium Mesons

In this research, we model Hulthén plus generalized inverse quadratic Yukawa potential to interact in a quark-antiquark system. The solutions of the Schrödinger equation are obtained using the Nikiforov-Uvarov method. The energy spectrum and normalized wave function were obtained. The masses of the heavy mesons for different quantum states such as 1S, 2S , 1P, 2P 3S, 4S, 1D, and 2D were predicted as 3.096 GeV, 3.686 GeV, 3.327 GeV, 3.774GeV, 4.040 GeV, 4.364GeV, 3.761 GeV, and 4.058 GeV respectively for charmonium (cc). Also, for bottomonium (bb) we obtained 9.460 GeV, 10.023 GeV, 9.841 GeV, 10.160 GeV, 10.345 GeV, 10.522 GeV, and 10.142GeV for different states of 1S , 2S , 1P , 2P , 3S , 4S , 1D respectively. The partition function was calculated from the energy spectrum, thereafter other thermal properties were obtained. The results obtained showed an improvement when compared with the work of other researchers and excellently agreed with experimental data with a percentage error of 1.60 % and 0.46 % for (cc) and (bb), respectively.

Errors in approximate ionization energies due to the one-electron space truncation of the EKT eigenproblem.

Unless the approximate wavefunction of the parent system is expressed in terms of explicitly correlated basis functions, the finite size of the generalized Fock matrix is unlikely to be the leading source of the truncation error in the ionization energy E produced by the EKT (extended Koopmans' theorem) formalism. This conclusion is drawn from a rigorous analysis that involves error partitioning into the parent- and ionized-system contributions, the former being governed by asymptotic power laws when the underlying wavefunction is assembled from a large number of spinorbitals and the latter arising from the truncation of the infinite-dimensional matrix V whose elements involve the 1-, 2-, and 3-matrices of the parent system. Quite surprisingly, the decay of the second contribution with the number n of the natural spinorbitals (NOs) employed in the construction of the truncated V turns out to be strongly system-dependent even in the simplest case of the 1S states of two-electron systems, following the n-5 power law for the helium atom while exhibiting an erratic behavior for the H- anion. This phenomenon, which stems from the presence of the so-called solitonic natural spinorbitals among the NOs, renders the extrapolation of the EKT approximates of E to the complete-basis-set limit generally unfeasible. However, attaining that limit is not contingent upon attempted reproduction of the ill-defined one-electron function known as "the removal orbital," which does not have to be invoked in the derivation of EKT and whose expansion in terms of the NOs diverges.

ATLAS results on charmonium production

An overview is given of the results on charmonium production obtained by the ATLAS collaboration at the LHC. Recent preliminary measurements covering prompt and non-prompt production of J/\psiJ/ψ and \psi(2S)ψ(2S) states in the range of high transverse momenta from 60 to 360~GeV are highlighted.

Measurement of ψ(2S) nuclear modification at backward and forward rapidity in p+p, p+Al , and p+Au collisions at sNN=200 GeV

Suppression of the J/ψ nuclear-modification factor has been seen as a trademark signature of final-state effects in large collision systems for decades. In small systems, the nuclear modification was attributed to cold-nuclear-matter effects until the observation of strong differential suppression of the ψ(2S) state in p+A and d+A collisions suggested the presence of final-state effects. Results of J/ψ and ψ(2S) measurements in the dimuon decay channel are presented here for p+p, p+Al, and p+Au collision systems at sNN=200GeV. The results are predominantly shown in the form of the nuclear-modification factor, RpA, the ratio of the ψ(2S) invariant yield per nucleon-nucleon collision in collisions of proton on target nucleus to that in p+p collisions. Measurements of the J/ψ and ψ(2S) nuclear-modification factor are compared with shadowing and transport-model predictions, as well as to complementary measurements at Large Hadron Collider energies.2 MoreReceived 9 February 2022Accepted 10 May 2022DOI:https://doi.org/10.1103/PhysRevC.105.064912©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasLeptonic, semileptonic & radiative decaysRelativistic heavy-ion collisionsPhysical SystemsCharmed mesonsHadron collidersMuonsQuarkoniaNuclear Physics

Experiments on the Electron Impact Excitation of the 2s and 2p States of Hydrogen Atoms Confirm the Presence of Their Second Flavor as the Candidate for Dark Matter

For the excitation of the n = 2 states of hydrogen atoms due to electron impact, we compared the experimental and theoretical ratios of the cross-sections σ2s/σ2p. We found this theoretical ratio to be systematically higher than the corresponding experimental ratio by about 20%—far beyond the experimental error margins. We suggest that this discrepancy can be explained by the presence of the Second Flavor of Hydrogen Atoms (SFHA) in the experimental hydrogen gas. The explanation is based on the fact that, in the experiments, the cross-section σ2s was determined by using the quenching technique—by applying an electric field that mixed the 2s and 2p states, followed by the emission of the Lyman-alpha line from the 2p state. However, the SFHA only had the s-states, so the quenching technique would not count the excitation of the SFHA in the 2s state and, thus, lead to the underestimation of the cross-section σ2s. We estimates the share of the SFHA in the experimental hydrogen gas required for eliminating the above discrepancy and found this share to be about the same as the share of the usual hydrogen atoms. Thus, our results constitute the third proof from atomic experiments that the SFHA does exist, the first proof being related to the experimental distribution of the linear momentum in the ground state of hydrogen atoms, and the second proof being related to the experimental cross-section of charge exchange between hydrogen atoms and low-energy protons.

Scattering amplitude and two-body loss of ultracold alkaline-earth atoms in a shaking synthetic magnetic field

The idea of manipulating the interaction between ultracold fermionic alkaline-earth (like) atoms via a laser-induced periodical synthetic magnetic field was proposed in Kanász-Nagy et al (2018 Phys. Rev. B 97, 155156). In that work, it was shown that in the presence of the shaking synthetic magnetic field, two atoms in 1S0 and 3P0 states experience a periodical interaction in a rotated frame, and the effective inter-atomic interaction was approximated as the time-averaged operator of this time-dependent interaction. This technique is supposed to be efficient for 173Yb atoms which have a large natural scattering length. Here we examine this time-averaging approximation and derive the rate of the two-body loss induced by the shaking of the synthetic magnetic field, by calculating the zero-energy inter-atomic scattering amplitude corresponding to the explicit periodical interaction. We find that for the typical cases with shaking angular frequency λ of the synthetic magnetic field being of the order of (2π) kHz, the time-averaging approximation is applicable only when the shaking amplitude is small enough. Moreover, the two-body loss rate increases with the shaking amplitude, and is of the order of 10−10 cm3 · s−1 or even larger when the time-averaging approximation is not applicable. Our results are helpful for the quantum simulations with ultracold gases of fermionic alkaline-earth (like) atoms.

Electrons and phonons in uranium hydrides - effects of polar bonding

GGA+U has been used as a framework for computational study of UH2, and α- and β-UH3, exploring specific features of the polar U-H bonding and its influence on magnetic and cohesion properties, including elastic parameters and vibrational properties. The description of the U-5f states with direct Coulomb U = 0.5 eV and equal exchange J = 0.5 eV not only reproduces equilibrium volumes but provides a realistic description of total magnetic moments, consisting of smaller spin and larger antiparallel orbital components. For UH2 and α-UH3, the spin-axis is aligned along the [111] direction. For β-UH3, there is a significant difference between both size and orientation U moments of atoms at the 2a and 6c Wyckoff positions. The former has U moments aligned along [111], while in the latter, not fixed to any specific direction by symmetry, they deviate by 10∘. The method corroborates previous bonding analyses, indicating a prominent hybridization and charge transfer, affecting the 6d and 7s states of U, being partly transferred to the H-1s states, as revealed by the Bader analysis. Analyzing individual effective inter-site magnetic coupling parameters it was possible to identify sources of relatively high Curie temperatures of 170 K for both UH3 variants and 120 K for UH2. Our results give predictions of elastic coefficients (consistent with the known bulk modulus in the case of β-UH3) and phonon densities of states, yielding expected infrared, Raman, and Hyper Raman active modes.

Photoionization cross sections of ultracold 88Sr in 1P1 and 3S1 states at 390 nm and the resulting blue-detuned magic wavelength optical lattice clock constraints.

We present the measurements of the photoionization cross sections of the excited 1P1 and 3S1 states of ultracold 88Sr atoms at 389.889 nm wavelength, which is the magic wavelength of the 1S0-3P0 clock transition. The photoionization cross section of the 1P1 state is determined from the measured ionization rates of 88Sr in the magneto-optical trap in the 1P1 state to be 2.20(50)×10-20 m2, while the photoionization cross section of 88Sr in the 3S1 state is inferred from the photoionization-induced reduction in the number of atoms transferred through the 3S1 state in an operating optical lattice clock to be 1.38(66) ×10-18 m2. Furthermore, the resulting limitations of employing a blue-detuned magic wavelength optical lattice in strontium optical lattice clocks are evaluated. We estimated photoionization induced loss rates of atoms at 389.889 nm wavelength under typical experimental conditions and made several suggestions on how to mitigate these losses. In particular, the large photoionization induced losses for the 3S1 state would make the use of the 3S1 state in the optical cycle in a blue-detuned optical lattice unfeasible and would instead require the less commonly used 3D1,2 states during the detection part of the optical clock cycle.

Contribution of the Sn 5s state to the SnS valence band: direct observation via ARPES measurements

Tin sulfide (SnS) is a compound semiconductor that has been studied for a wide range of applications, including solar cells and thermoelectric materials. In this study, the electronic structure of the SnS valence band, which is important for such applications, was investigated via angle-resolved photoelectron spectroscopy with two different excitation energies in the extreme ultraviolet region (21 and 60 eV). The contribution of the Sn 5s state to the SnS valence band was determined in relation to the k-vector by utilizing the fact that the cross section of Sn 5s state varies significantly compared to those of other states in the extreme ultraviolet region. The experimental results demonstrate that the Sn 5s state significantly contributed to the k-vector around the valence band maximum (VBM) and second VBM (VBM1).

Charge transfer of potassium by the impact of proton particle

The total cross section for electron capture is being calculated in this paper for 2s state of hydrogen atom in proton-potassium collision. The energy range chosen for the calculation is 50 keV to 10,000 keV and we have used Coulomb projected Born (CPB) approximation method. Also the differential cross section at different scattering angle has been calculated. The result obtained are compared with available theoretical data and found it to be in good agreement.

Efficient Yellow Self-Trapped Exciton Emission in Sb3+-Doped RbCdCl3 Metal Halides.

Metal halide perovskites have flexible crystal and electronic structures and adjustable emission characteristics, which have very broad applications in the optoelectronic field. Among them, all-inorganic perovskites have attracted more attention than others in recent years because of their characteristics of large diffusion length, high luminescence efficiency, and good stability. In this work, Sb3+-doped RbCdCl3 crystalline powder was synthesized by a simple hydrothermal method, and its luminescence properties were studied, which showed a broad emission band with a large Stokes shift and efficient yellow light emission at about 596 nm at room temperature with a photoluminescence quantum yield of 91.7%. The emission came from the transition of the self-trapped exciton 1 (STE1) out of 3Pn (n = 0, 1, and 2) to S0 due to strong electron-phonon coupling, which scaled with increasing temperature. Moreover, its emission color became white at low temperatures due to the occurrence of transition of other self-trapped exciton 0 (STE0) state emission out of the 1S states of Sb ions to S0 in the lattice. These emission color changes may be used for temperature sensing, and this Sb3+-doped RbCdCl3 material expands the knowledge of the efficient luminescent inorganic material family for further applications of all-inorganic perovskites.

Electronic Structure of Tl<sub>4</sub>CdI<sub>6</sub>: First-Principles Calculations and X-Ray Photoelectron Spectroscopy Measurements

We report on experimental and theoretical studies of the electronic structure of ternary Tl4CdI6 alloy. Our XPS results indicate low hygroscopicity of its surface. The first-principle calculations indicate that the valence-band region of Tl4CdI6 is dominated by contributions of I 5p states (mainly at the top and the central portion), while its bottom is prevailed by contributions of Tl 6s states. The theoretical data indicate that the Tl4CdI6 compound is a direct gap semiconductor with the band gap value of Eg = 2.03 eV. The calculations reveal that the significant covalent component (in addition to ionic component) is characteristic for the chemical Tl–I and Cd–I bonds of Tl4CdI6.

Electronic and optical responses, Compton spectroscopy and manifestation of trapping centres of LiF:Mg,Ti

Electronic structure to judge trapping centres and activation energies in Mg-doped (2–8%) and Mg,Ti co-doped (2–3% each) LiF phosphors are presented using full-potential linearized APW method. Compton measurement for LiF is performed for appropriate choice of exchange-correlation potentials used in electronic properties. It is seen that 2–6% of Mg activator leads to formation of electronic traps with activation energy between 0.79 and 0.49 eV. At high concentration (>6%) of Mg, the formation of trap centres vanishes. Co-doping of 2% Mg,Ti permits the formation of trap centres, which is in contrast to higher concentrations. Mg-3s states play key role in the building of electronic trap centres. Higher concentration of Ti and Mg activators in LiF leads to the widening of 3d and 3s states, respectively. Analysis of optical response (frequency-dependent dielectric constants, trapping centres, and absorption coefficients) of 2% Mg-doped and 2% Mg,Ti co-doped LiF suggest their dosimetric applications and in ultra-violet detection.

Excitation spectra of heavy baryons in diquark models

Abstract The excitation energy spectra of heavy baryons consisting of a heavy quark and two light quarks are investigated using diquark models in order to examine the nature of the diquark as a constituent of single heavy baryons. We consider two diquark models; in Model A the diquark is treated as a point-like particle, while it has a spatial size in Model B. We determine the masses of scalar and axial vector diquarks by the mass difference of the ground-state charmed baryons and the Λc baryon, while the mass of the ud scalar diquark in the Λc baryon is assumed to be 500 MeV as a reference. The parameters of these models are fixed by the 1p excitation energy of Λc. We find that Model A reproduces well the excitation energy spectra of the charmed and bottomed baryons, although the string tension of the confinement potential in Model A should be half of that of the charmonium, while Model B suggests degeneracy of the 2s and 1d states, which is not seen in the Λc spectrum.

Determination of |Vcb| using N3LO perturbative corrections to Γ(B → Xcℓν) and 1S masses

We determine |Vcb| using the third-order perturbative series for the inclusive semileptonic B decay width and for the masses of the bottomonium 1S states. We use the masses of ηb(1S) and ϒ(1S) as short-distance masses and point out that there is a sizable difference of |Vcb| between the two 1S mass schemes. This is the dominant error of our determination and stems from insufficiency to describe theoretically the observed mass splitting of the bottomonium 1S states. We also study the significance of the O(ΛMS‾2) non-perturbative effects in HQET with respect to the current perturbative accuracy. Our result |Vcb|=0.0425(11) is consistent with the PDG value determined from the inclusive decays and has a slightly larger error.

Dipole–Dipole Polarizability of the Cadmium 1S0 State Revisited

Experimental results and high-level quantum chemical ab initio calculations of the static polarizability $\alpha_0=\alpha(\omega=0)$ of the cadmium ${^1S_0}$ state are still in marked disagreement. Here we analyze this discrepancy by using experimentally determined dipole oscillator strength distributions (DOSD). It will be shown that within this procedure the experimentally determined static polarizability $\alpha_0$ will shift from $49.7 \pm 1.6~$au to considerably lower values. We now conclude an experimentally determined polarizability of $\alpha_0=47.5 \pm 2.0~$au in much better agreement with the latest calculations of $\alpha_0 \approx 46~$au.

Non-adiabatic dynamics of Rydberg-excited diethylamine

Femtosecond time-resolved photoelectron spectroscopy was employed to investigate the ultrafast non-adiabatic dynamics of diethylamine (DEA). Following the direct excitations of the two main conformational structures (i.e., TT and TG) of DEA to the 3p Rydberg states at 200 nm, DEA undergoes internal conversion to the 3s state with ∼68 fs, which is similar to previously relaxation pathways of several secondary and tertiary amines. Subsequent dynamics on the 3s Rydberg state evolves along the NH stretching coordinate and is then accompanied by the breaking of the NH bond in about 120 fs, rather than the cleavage of the NC, or CC bonds as well as the conformational transformations between the TT and TG conformers on the 3s states. Theoretically, we reveal the pre-dissociative nσ* character evolving along the NH stretching coordinate within the 3s state as DEA dissociates to yield H atom products. As contrasted to the well-known conformational NC bond rotation motions in systems such as tertiary amines, the non-adiabatic relaxation of the 3s state of DEA is predominantly characterized by the NH bond dissociation process.

Автоиончлолд мөргөлдөөний дараах харилцан үйлчлэл ба туршлагын ялгах чадварын нөлөөнд өгөх тайлбар

Following the ideas kf Balashow, Martin and Crow we have isolated the resonant part of the transition amplitude for auto-ionization from the 2S state, in several different ways 1) from the pure theoretical T matrix, 2) from the theoretical cross section using Shore parameters and 3) from an experimental cross section where the theoretical cross section has been convoluted whit an experimental resolution. Our conclusion is that variations of the o-parameter reported in [1] is a result of both post-collisional interaction as well as an effect of the experimental resolution.

Influence of Post-Collision-Interaction in Auto-ionization

Following the ideas of Senashenko we obtain an expression for the resonant part of the auto-ionizing transition matrix consisting of the standart first Born expression, and an additional factor containing the remaining effects of Post-Collision-Interaction. This factor becomes very important when one studies the angular dependence of auto-ionization from spherical symmetric auto-ionization states. We in particular concentrate on decay form the (2s2)1S state since an experimental investigation of this process has recently been published.