arXiv subjects

Kaan Şimşek

Publications and source records attributed to Kaan Şimşek.

4 recordsLinked to original sources

arXiv2026

$t\bar t$ production as a probe of dimension-six SMEFT at higher orders

We study top-antitop pair production in proton-proton collisions within the Standard Model effective field theory (SMEFT) at dimension six. We focus on the top chromomagnetic operator $C_{tG}$ together with the four-quark operators relevant for unpolarized $t{\bar t}$ production. We analyze the top-quark single-differential transverse-momentum ($p_T$) and rapidity ($y$) distributions and the double-differential distributions in $p_T$ and $y$ ($p_T\times y$) at 13~TeV, and we present projections for 13.6~TeV using the same binning. Our highest-order setup combines next-to-next-to-leading-order (NNLO) Standard Model (SM) predictions with approximate NNLO SM-SMEFT interference corrections. We find that higher-order QCD effects are essential for a stable SMEFT interpretation, yielding substantially more robust bounds and milder parameter degeneracies. The strongest sensitivity is obtained for $C_{tG}$. In the combined highest-order analysis of the 13-TeV results and 13.6-TeV projections, we obtain sensitivity to effective scales up to $3.9~\TeV$. Our results show that higher-order differential top-pair production provides a precise and theoretically controlled probe of the top chromomagnetic interaction.

hep-ph↗

arXiv2026

N$^3$LO soft-gluon corrections for $Zγ$ production

We calculate soft-gluon corrections for $Zγ$ production through next-to-next-to-next-to-leading-order (N$^3$LO) in one-particle-inclusive (1PI) kinematics. We use these results to produce approximate N$^3$LO (aN$^3$LO) QCD predictions for $Zγ$ production cross sections in proton-proton collisions at LHC energies. Differential cross sections in photon transverse momentum $p_T^γ$ and rapidity $y^γ$ are computed at 13 TeV and 13.6 TeV collider energies. Higher-order $K$-factors are examined systematically, and scale and PDF uncertainties are quantified at each perturbative order. Soft-gluon corrections are found to be significant in the high-$p_T$ region, with good perturbative convergence observed at aN$^3$LO.

hep-ph↗

arXiv2026

Constraining dimension-6 SMEFT with higher-order predictions for $p p \to t W$

We study single-top production in association with a $W$ boson at the Large Hadron Collider (LHC) as a probe of dimension-6 Standard Model effective field theory (SMEFT) at leading order, next-to-leading order, and approximate next-to-next-to-leading order accuracy in quantum chromodynamics (QCD). The process is sensitive to operators that modify the top-quark weak and chromomagnetic dipole interactions, and we perform three-parameter linear and quadratic SMEFT fits using doubly differential top-quark distributions in transverse momentum and rapidity for the Run II and Run III configurations at the LHC. We provide a detailed account of the uncertainties and quantify the impact of the different uncertainty components across bins and perturbative orders. We find that effective scales up to 2 TeV can be probed in nonmarginalized fits, while in marginalized fits the corresponding scales are around 0.5 and 1.5 TeV for linear and quadratic fits, respectively.

hep-ph↗

arXiv2026

Naive $T$-odd Drell-Yan angular coefficients as a probe of the dimension-8 SMEFT

We propose the ``naive" $T$-odd Collins-Soper moments in the Drell-Yan process as probes of previously unexplored directions in the Standard Model Effective Field Theory (SMEFT) parameter space. We show that the moments $A_6$ and $A_7$ in the high invariant mass and transverse momentum region are sensitive to dimension-8 $CP$-odd semi-leptonic four-fermion operators with an additional gluon field strength tensor. Using the projected integrated luminosity of a future high-luminosity LHC, we show that effective ultraviolet scales in the few-TeV range can be probed with this process.

hep-ph↗