hep-ex updates on arXiv.org

http://rss.arxiv.org/rss/hep-ex

Probing CP and flavor violation in neutral kaon decays with ALPs

2025-07-0304:00

arXiv:2507.01947v1 Announce Type: cross Abstract: We analyze the three-body decays of the long-lived neutral kaon $K_L \to \pi\pi a$, where $a$ is an axion-like particle (ALP), and compare them to the two-body decay $K_L \to \pi^0 a$. While the latter requires both flavor violation (FV) and $CP$ violation (CPV), the former can proceed via FV alone, allowing the ratio of decay rates to serve as a probe of CPV of the underlying UV theory. We emphasize the importance of weak-interaction-induced contributions, often neglected in recent calculations. We explore both minimal and non-minimal flavor-violating scenarios, and identify classes of models where ALP production from neutral three-body decays is comparable to - or even dominates over - the two-body decay, despite its reduced phase space. Finally, we discuss the phenomenological implications of our results and show how these decays can provide complementary probes of ALP couplings beyond those accessible via charged kaon channels.

Nuclear Physics Confronts Relativistic Collisions Of Isobars

2025-07-0304:00

arXiv:2507.01454v1 Announce Type: cross Abstract: High-energy collisions involving the $A=96$ isobars $^{96}$Zr and $^{96}$Ru have been performed in 2018 at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) as a means to search for the chiral magnetic effect in QCD. This would manifest itself as specific deviations from unity in the ratio of observables taken between $^{96}$Zr+$^{96}$Zr and $^{96}$Ru+$^{96}$Ru collisions. Measurements of such ratios (released at the end of 2021) indeed reveal deviations from unity, but these are primarily caused by the two collided isobars having different radial profiles and intrinsic deformations. To make progress in understanding RHIC data, nuclear physicists across the energy spectrum gathered in Heidelberg in 2022 as part of an EMMI Rapid Reaction Task Force (RRTF) to address the following question. Does the combined effort of low-energy nuclear structure physics and high-energy heavy-ion physics enable us to understand the observations made in isobar collisions at RHIC?

Precision determination of $\alpha_\text{s}$ from Dijet Cross Sections in the Multi-TeV Range

2025-07-0304:00

arXiv:2507.01670v1 Announce Type: cross Abstract: In this talk we present a determination of the strong coupling constant $\alpha_\text{s}$ and its energy-scale dependence based on a next-to-next-to-leading order (NNLO) QCD analysis of dijet production. Using the invariant mass of the dijet system to probe $\alpha_\text{s}$ at different scales, we extract a value of $\alpha_\text{s}(m_\text{Z})=0.1178 \pm 0.0022$ from LHC dijet data. The combination of various LHC datasets significantly extends the precision and scale reach of the analysis, enabling the first determination of $\alpha_\text{s}$ up to 7 TeV. By incorporating dijet cross sections from HERA, we further probe $\alpha_\text{s}$ at smaller scales, covering a kinematic range of more than three orders of magnitude. Our results are in excellent agreement with QCD predictions based on the renormalization group equation, providing a stringent test of the running of the strong coupling across a wide energy range.

3