arXiv subjects

Andrei Poblaguev

Publications and source records attributed to Andrei Poblaguev.

9 recordsLinked to original sources

arXiv2026

Modeling a Framework for Comprehensive Analysis of $\boldsymbol{p^\uparrow\!{A}}$ Transverse Analyzing Power Measurements at the RHIC HJET

We present a model for calculating the forward elastic analyzing power $A_\text{N}^{pA}(t)$ in proton-nucleus scattering, based on the Glauber approximation and incorporating soft-photon exchange corrections. The model is tested against 100 GeV HJET measurements for several nuclei, including Au, Ru, Zr, Al, O, C, and the deuteron. The calculations use Woods-Saxon parameters to describe the nuclear density distributions, as well as the proton-proton and proton-neutron hadronic spin-flip amplitudes, with the latter constrained by a Regge fit to HJET $pp$ data. Using the nominal input parameters, the calculations provide a reasonable description of the measured analyzing powers, although further refinement is needed to achieve a satisfactory fit. Allowing the input parameters to vary in the fits substantially improves the agreement with the data, yielding effective parametrizations of $A_\text{N}^{pA}(t)$ in terms of three or four parameters, depending on the nucleus. Notably, the nominal values of the imaginary part of the effective proton-nucleus spin-flip parameter $r_5^{pA}$ agree well with the fitted values for all nuclei considered. Subject to the limitations of the present model, this observation concerning $\operatorname{Im} r_5^{pA}$ is consistent with the proton-proton spin-flip amplitudes measured at HJET and supports the interpretation of a non-zero Pomeron spin-flip coupling. The results presented in this paper also motivate further investigation of the energy dependence of the proton-nucleon spin-flip amplitude using HJET measurements over a broad range of beam energies, with potential applications to proton-carbon and $^3$He polarimetry at the Electron-Ion Collider.

hep-ph↗

arXiv2026

Comments on the paper "Eliminating beam-induced depolarizing effects in the hydrogen jet target for high-precision proton beam polarimetry at the Electron-Ion Collider"

A critical review of the methodology used in F. Rathmann et al., Phys. Rev. Accel. Beams 29, 021001 (2026), to evaluate beam-induced depolarization of the Atomic Polarized Hydrogen Gas Jet (HJET) target at the Electron--Ion Collider (EIC) is presented. It is shown that several key assumptions underlying that analysis -- including the introduction of a photon emission threshold, the application of Fermi's Golden Rule to coherent hyperfine transitions, the interpretation of power broadening as a physical linewidth increase, and the treatment of spatial magnetic fields -- are either incorrect or internally inconsistent. As a consequence, the predicted large depolarization effects are demonstrated to be artifacts of the adopted methodology rather than genuine physical phenomena. A consistent quantum-mechanical treatment based on the time-dependent Schrödinger equation shows that beam-induced depolarization probabilities at the EIC are negligibly small.

physics.acc-ph↗

arXiv2026

Coulomb corrections for the non-flip and spin-flip electromagnetic $\boldsymbol{p}^\uparrow\!\boldsymbol{A}$ amplitudes

It is demonstrated that, within the eikonal approach, the Coulomb corrections to the elastic electromagnetic non-flip and spin-flip proton--nucleus amplitudes are identical when the two amplitudes share the same exponential form factors. This result allows Coulomb corrections to be computed numerically, and with high precision, for both electromagnetic and hadronic elastic $p^{\uparrow}A$ amplitudes in the massless-photon limit, including the effects of soft magnetic photon exchange. The method relies on analytical expressions and numerical integrations over a finite impact-parameter range with nonsingular integrands, providing a practical and systematically controlled framework for phenomenological applications.

hep-ph↗

arXiv2025

Numerical Calculation of Coulomb Corrections in Forward Elastic $p^\uparrow\!\!\;{p}$ and ${p}^\uparrow\!{A}$ Scattering

The analysis of RHIC hydrogen gas jet target polarimeter measurements of transverse analyzing powers $A_\text{N}(t)$ in proton-nucleus scattering requires accurate Coulomb corrections to both spin-flip and non-flip amplitudes. These corrections must cover a wide range of nuclear charges $Z$ and form factor slopes, with flexibility to vary form factors during data fitting. To avoid technically challenging calculations involving a small but finite fictitious photon mass, the Coulomb correction to the non-flip electromagnetic amplitude with an exponential form factor was related to the corresponding correction for the spin-flip amplitude. This approach allows soft photon contributions to all amplitudes, including those with non-exponential form factors, to be calculated in the massless photon limit using only analytical expressions and numerically stable integrals with nonsingular integrands and finite integration limits. In addition, an absorptive correction to the spin-flip electromagnetic amplitude, which plays a critical role in spin effects in forward polarized proton-nucleus scattering, was accurately evaluated.

hep-ph↗

arXiv2025

Realizing the Scientific Program with Polarized Ion Beams at EIC

Polarized ion beams at the Electron Ion Collider are essential to address some of the most important open questions at the twenty-first century frontiers of understanding of the fundamental structure of matter. Here, we summarize the science case and identify polarized $^2$H, $^3$He, $^6$Li and $^7$Li ion beams as critical technology that will enable experiments which address the most important science. Further, we discuss the required ion polarimetry and spin manipulation in EIC. The current EIC accelerator design is presented. We identify a significant R\&D effort involving both national laboratories and universities that is required over about a decade to realize the polarized ion beams and estimate (based on previous experience) that it will require about 20 FTE over 10 years (or a total of about 200 FTE-years) of personnel, including graduate students, postdoctoral researchers, technicians and engineers. Attracting, educating and training a new generation of physicists in experimental spin techniques will be essential for successful realization. AI/ML is seen as having significant potential for both acceleration of R\&D and amplification of discovery in optimal realization of this unique quantum technology on a cutting-edge collider. The R\&D effort is synergistic with research in atomic physics and fusion energy science.

nucl-ex↗

arXiv2024

Absorptive corrections to the electromagnetic form factor in high-energy elastic proton-proton scattering

Recently, it was noted that absorptive corrections to the electromagnetic form factor in high-energy proton-proton scattering are important for the theoretical interpretation of the $p^\uparrow{p}$ and $p^\uparrow{A}$ analyzing power $A_\text{N}(t)$ measurements with the Hydrogen Jet Target polarimeter (HJET) at RHIC. Here, a concise expression for the absorptive correction was derived within the eikonal approach. The resulting analysis reveals a systematic bias, nearly independent of the beam energy, in the experimental determination of the real-to-imaginary ratio $ρ$ when absorption effects are overlooked in the data analysis. Quantification of this bias, as $ρ^\text{meas}=ρ+ (0.036\pm0.016)_\text{bias}$, was achieved using a Regge fit applied to available proton-proton measurements of $ρ^\text{meas}(s)$ and $σ^\text{meas}_\text{tot}(s)$. Considering the potential impact of such an effect on the experimentally determined $A_\text{N}(t)$, one may enhance consistency between the HJET and STAR measurements of the hadronic spin-flip amplitude. While the sign of the bias in the value of $ρ$ aligns with the anticipated effective increase in the proton charge radius in $pp$ scattering due to absorption, it amplifies the observed discrepancy between $σ^\text{meas}_\text{tot}$ and $ρ^\text{meas}$ values at $\sqrt{s}=13\,\text{TeV}$ as measured in the TOTEM experiment. Evaluation (using published TOTEM data) of the measured proton-proton $dσ/dt$ dependence on the absorptive corrections indicated that possible soft photon corrections to the hadronic amplitude slope may be essential for such data analysis.

hep-ph↗

arXiv2024

Polarization Measurements of $p^{\uparrow}$ and $^3$He$^\uparrow$ Beams at RHIC and Future EIC Using the Polarized Atomic Hydrogen Gas Jet Target

At the Relativistic Heavy-Ion Collider (RHIC), the Polarized Atomic Hydrogen Gas Jet Target polarimeter (HJET) is employed for the precise measurement of the absolute transverse (vertical) polarization of proton beams, achieving low systematic uncertainties of approximately $σ^\text{syst}_P/P\leq0.5\%$. The acquired experimental data not only facilitated the determination of single $A_\text{N}(t)$ and double $A_\text{NN}(t)$ spin analyzing powers for 100 and 255 GeV proton beams but also revealed a non-zero Pomeron spin-flip contribution through a Regge fit. Preliminary results obtained for forward inelastic $p^{\uparrow}p$ and elastic $p^{\uparrow}A$ analyzing powers will be discussed. The success of HJET at RHIC suggests its potential application for proton beam polarimetry at the upcoming Electron-Ion Collider (EIC), aiming for an accuracy of 1\%. Moreover, the provided analysis indicates that the RHIC HJET target can serve as a tool for the precision calibration, with the required accuracy, of the $^3$He beam polarization at the EIC.

nucl-ex↗

arXiv2023

Breakup corrections to spin asymmetries in the $^3$He beam polarization measurements with the Polarized Atomic Hydrogen Gas Jet Target

The requirements for hadron polarimetry at the future Electron Ion Collider (EIC) include measurements of the absolute helion ($^3$He, $h$) beam polarization with systematic uncertainties better than $σ^\text{syst}_P/P\le1\%$. Recently, it was proposed that the Polarized Atomic Hydrogen Gas Jet Target (HJET) be utilized for the precision measurement of the polarization of the $\approx100~\text{GeV/n}$ helion beam. At the Relativistic Heavy Ion Collider, HJET serves to determine the absolute proton beam polarization with low systematic uncertainties of about $δ^\text{syst}P/P\lesssim0.5\%$. To adapt the HJET method for the EIC helion beam, the experimentally determined ratio of the beam and target (jet) spin-correlated asymmetries should be adjusted by the ratio of $p^\uparrow{h}$ and $h^\uparrow{p}$ analyzing powers. A potential problem with the suggested method is that the breakup of $^3$He in polarization measurements could drastically affect the analyzing power ratio. However, an analysis of the breakup corrections, presented in this paper, reveals that while these corrections can be as substantial as $\approx4\%$, the effect cancels out to a negligible level in the measured beam polarization.

hep-ph↗

arXiv1996

Muon Polarization Working Group Report

We have examined the physics and the experimental feasibility at the AGS of various kaon decay processes in which the polarization of a muon in the final state is measured. Valuable information on CP violation, the CKM matrix or new physics can be obtained with these measurements and therefore they are well motivated. In particular, models of non-standard CP violation that produce the baryon asymmetry of the universe could also produce effects observable in these measurements. Limits from measurements such as the neutron and electron electric dipole moment, and epsilon-prime over epsilon in neutral kaon decays do not eliminate all of these models. We have made a more detailed examination of the measurement of the out of the plane muon polarization in Kmu3 decays. With our current knowledge of the AGS kaon beams and detector techniques it is possible to measure this polarization with an error approaching 10**-4. Such an experiment would be well justified since the sensitivity is well beyond the current direct experimental limit (5.3 times 10**-3) and the projected sensitivity (10**-3) of the currently running experiment at KEK in Japan.

hep-ex↗