arXiv subjects

Arkadiy I. Syamtomov

Publications and source records attributed to Arkadiy I. Syamtomov.

10 recordsLinked to original sources

arXiv2026

From cross-section degeneracies to phase-sensitive observables in near-threshold J/psi production

Near-threshold $J/ψ$ production is sensitive to scalar and traceless spin-two chromoelectric structure in the nucleon. We study whether present integrated and differential measurements can separate these contributions and constrain their relative phase. The GlueX integrated cross section does not determine a unique scalar contribution: production and elastic scalar terms are strongly correlated, while flatter non-forward profiles drive the fitted scalar strength to zero. In a 38-point large-$ξ$ differential analysis, the scalar term is collinear at fixed kinematics with the retained C-GFF direction, leading to nearly degenerate solutions and strong profile dependence. A common single-channel final-state factor preserves the scalar-spin-two relative phase, whereas coupled-channel rescattering can modify it. Its determination therefore requires polarization-sensitive observables together with process-specific complex helicity amplitudes.

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arXiv2026

Near-Threshold OPE Constraints and High-Energy Diffractive Dynamics in J/psi Photoproduction

We study the forward $J/ψN$ amplitude $M_{ψN}(λ)$ using a leading-twist Coulombic operator-product expansion, exact physical-domain target-mass resummation, and modern gluon PDFs. Forward-intercept extrapolations reported by GlueX and CLAS12 constrain the amplitude modulus within a vector-meson-dominance normalization. After fitting an overall scale and a subtraction constant, the exact-TMC and no-TMC descriptions differ by only $Δχ^2=0.021$, while a two-parameter empirical exponential gives an equally good fit. The point $C_{\rm sub}=0$ changes the profiled minimum by only $0.033$. Current near-threshold data therefore determine neither the target-mass correction nor the subtraction constant separately. An independent correlated fit to HERA data gives $δ=0.695\pm0.023$. The absence of direct-proton measurements between $W\simeq4.73$ and $20~\mathrm{GeV}$ prevents a data-driven determination of the crossover to high-energy diffraction.

hep-ph↗

arXiv2026

QCD-Matched Gluonic Response in Heavy-Quarkonium Born-Oppenheimer EFT: Locality, Channel Factorization, and the Peskin Limit

We formulate a source-dependent QCD-to-BOEFT matching for the gluonic response of a stable compact heavy-quarkonium state. The matched complementary-space resolvent preserves coupled Born-Oppenheimer dynamics, while an exact Feshbach decomposition separates channels retained explicitly from sectors integrated out at the next matching step. Spectral separation, kernel analyticity, and joint propagation-source bounds provide sufficient conditions for a local channel-factorized OPE; otherwise low-energy BO poles and cuts remain dynamical. The weak-coupling pNRQCD response is recovered as a limiting reference problem. With the additional leading-$E1$, large-$N_c$/free-octet assumptions, the source-weighted spectral measure reproduces the established Bhanot-Peskin electric moments and dissociation cut. For a Coulombic spin-singlet $1S$ state we also obtain the sequential-$M1$ contribution $c_{B,GG}^{(1)ij} =5πα_s^2(c_FV_{\rm iso}^{(s)})^2δ^{ij}/16$ and the covariant-kinetic seagull contribution $c_{B,\mathrm{dia}}^{(1)ij} =-πα_s^2δ^{ij}/4$. These are identifiable components, not the complete magnetic matching coefficient.

hep-ph↗

arXiv2026

Complex chromoelectric polarizability of a heavy-quarkonium resonance: pole definition and channel-complete pNRQCD matching

For a stable compact quarkonium, chromoelectric polarizability is generated by two E1 transitions through virtual color-octet states. An unstable quarkonium is instead defined by an isolated complex pole. We define its polarizability by the quadratic displacement of that pole. Combining the standard pole-residue definition of resonance properties with pNRQCD matching shows that the complete two-field vertex is normalized by the energy derivative of the full inverse propagator. Its numerator contains octet E1-E1 propagation, the field dependence of decay channels, and local hard matching terms, without double counting. The stable-state result is recovered with its standard sign and color factor. A minimal single-threshold model calibrated to the Psi(3770) pole gives, within its specified field convention, the residue factor 0.800-0.336i. This illustrates a potentially sizable normalization effect but is not a model-independent pole observable. The absolute polarizability still requires quarkonium and channel response inputs.

hep-ph↗

arXiv2026

Chromoelectric and chromomagnetic matching to scalar and spin-two nucleon structure

Compact heavy quarkonium couples through the multipole interaction to scalar and spin-two gluonic operators. At leading chromoelectric order the corresponding matching coefficients satisfy $C_2^Φ=-C_S^Φ$; an independent chromomagnetic polarizability lifts this relation within the general CP-even, spin-independent, local two-gluon interaction at dimension four and zero derivative order. We construct an RG-consistent realization in a fixed $MS$ convention. The QCD trace identity converts the gluon-only scalar matching condition into an invariant basis and fixes the correlated quark-mass coefficient required when the interaction is re-expressed in the scale-dependent basis away from the matching scale, whereas leading-logarithmic singlet evolution induces a quark spin-two coefficient. In threshold-aligned symmetric kinematics, the canonical-spin non-flip projection contains $A_i(t)$ and the combination $3B_i(t)-D_i(t)$. An explicit Breit-frame calculation relates this projection to an off-diagonal helicity representation for nonzero spacelike $t$; the off-diagonal form is kinematic rather than an additional dynamical spin flip. Linearity of the scalar and spin-two evolution factorizes the chromomagnetic dependence of their ratio as $R_{2/0}^Φ(t;ρ_Φ)=[(1+ρ_Φ)/(1-ρ_Φ)]R_{2/0}^Φ(t;0)$ within the gluon-only dimension-four matching setup. The result separates state-dependent quarkonium matching from scalar and gravitational nucleon structure and states explicitly the assumptions under which this factorization holds.

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arXiv2026

Light-front diagnostics in the 't Hooft model: II. Boundary cancellations, ERBL spectral sums, and analyticity of the EMT form factor

A diagonal light-front overlap contains near-forward energy-momentum-tensor (EMT) information but is not itself a local matrix element. In the large-$N_c$ 't Hooft model we complete the second GPD moment with its ERBL contribution and follow how the two support regions combine. Boundary exponents generate fractional powers and, at $β=1/2$, resonant logarithms in the separate terms. We show that these structures cancel, including the interference of the leading and next indicial families. At the resonance, cancellation of the double and single logarithms also yields an inverse-mass-squared residue sum rule; above it, the two regions combine into a finite fourth-order coefficient. The complete EMT form factor is therefore analytic through curvature order. The ERBL sector leaves the slope unchanged but is essential for curvature and higher derivatives. We extract stable canonical and heavy curvatures, estimates with systematic envelopes for the second and third light excitations, and the longitudinal trace radius. The intermediate-state decomposition further shows how constituent mass and excitation redistribute pole strength and generate removable poles and interference zeros.

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arXiv2026

Light-front transverse profiles of scalar and spin-two chromoelectric EMT responses in near-threshold charmonium probes

I construct light-front transverse profile functions for the scalar and spin-two chromoelectric energy-momentum-tensor responses selected by compact-charmonium probes of the proton. The scalar branch is the anomaly and sigma amplitude, while the spin-two branch contains the gravitational combination $3B_i(t)-D_i(t)=6J_i(t)-3A_i(t)-D_i(t)$ rather than $A_i(t)$ alone. In the Drell-Yan frame, these two amplitudes define normalized transverse response profiles whose integrated ratio reproduces the forward light-front spin-two/scalar strength, while the finite transverse-distance behavior is sensitive to the relative scalar and gravitational slopes. The construction gives a spatial representation of the chromoelectric EMT projection without interpreting a measured near-threshold slope as a model-independent static three-dimensional mass radius.

hep-ph↗

arXiv2026

Scalar and spin-two energy-momentum-tensor structure in near-threshold charmonium probes of the proton

I analyze the energy-momentum-tensor (EMT) content of the chromoelectric operator that governs the leading interaction of compact charmonium with soft gluonic fields. In the renormalized MS operator basis this interaction separates into a scalar anomaly/sigma branch and a traceless spin-two branch. The forward light-front spin-two term is fixed by partonic plus-momentum fractions and gives a controlled correction to scalar dominance. Off forward, however, the chromoelectric spin-two contraction is not governed by $A_i(t)$ alone; it also contains the combination $3B_i(t)-D_i(t)$, equivalently $6J_i(t)-3A_i(t)-D_i(t)$. This identifies which EMT structures charmonium can access in forward and differential observables, without interpreting the measured slope as a model-independent static three-dimensional mass radius.

hep-ph↗

arXiv2026

Light-front diagnostics in the 't Hooft model: I. Wave functions, EMT decomposition, and the diagonal GPD overlap

I examine how the longitudinal light-front wave function of a meson encodes forward energy-momentum tensor (EMT) structure and the diagonal part of an off-forward generalized parton distribution in the large-$N_c$ 't~Hooft model. Light-light, equal-mass reference, heavy-light, and heavy-heavy systems are compared through their momentum distributions, differential entropy, bilocal Coulomb kernel, and forward mass-squared decomposition. An independent sine-basis calculation confirms the light-light spectrum despite the slow convergence of the sine representation. For equal constituent masses, the second moment obtained from the exact diagonal overlap has no term linear in the asymmetric skewness variable $b$, while its regular $b^2$ and $b^3$ coefficients are equal and determined by a universal kinematic contribution and a weighted wave-function gradient norm. At the equal-mass reference point, corresponding to $β=1/2$, the boundary expansion becomes resonant and generates a $b^4\ln^2(1/b)$ nonanalyticity, identifying the precise limitation of the diagonal two-body overlap. The companion Part II analysis constructs the ERBL completion required to cancel this support-dependent nonanalyticity and restore the analyticity of the local EMT moment.

hep-ph↗

arXiv2026

Target-Mass Corrections in the OPE Sum-Rule Approach to Quarkonium-Nucleon Interactions with Global-Fit PDFs: an $x$-Resolved Analysis

We derive an exact all-orders treatment of target-mass corrections (TMCs) within the leading-twist Coulombic OPE for the absorptive quarkonium-nucleon spectral baseline. Resumming the complete trace series before analytic continuation yields a closed spectral kernel, a shifted-convolution expression, and a moment representation that preserves the on-shell incoming domain $0<y\leq1$, with $y=m_N/λ$ and $λ$ the nucleon energy in the quarkonium rest frame. Using native ABMP16, MSHT20, CT18, and NNPDF4.0 grids, we find at $Q=10$~GeV and $ε_0=0.16$~GeV that the TMC/no-TMC moment ratio decreases from about $0.85$ at $n=4$ to $0.42$-$0.48$ at $n=12$. At the first tabulated energies above the incoming two-body endpoint, the leading-twist cross-section ratio is strongly suppressed but rapidly approaches unity with increasing energy. The strict endpoint has an integrable inverse-velocity behaviour, whose hadronic-threshold interpretation lies outside the leading-twist construction.

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