arXiv subjects

Zachary Wüthrich

Publications and source records attributed to Zachary Wüthrich.

4 recordsLinked to original sources

arXiv2026

Decay constants of the $B_c$ mesons with vector and tensor currents

We calculate the decay constants of the lowest-lying $B_c$ mesons in the spin-parity channels $J^P = 0^-,\,0^+,\,1^-,\,1^+$, commonly referred to as the $B_c,\, B_{c0}^*,\, B_c^*,\, B_{c1}$ mesons, respectively. Within the framework of QCD sum rules, we consider the decay constants associated with both the (axial-)vector and (axial-)tensor interpolating currents. The decay constants with (axial-)vector currents have already been studied in the literature. We refine previous QCD sum rule results by including higher-order power corrections and performing a comprehensive uncertainty analysis. Furthermore, we provide the first determination of the (axial-)tensor decay constants of the $B_c^*$ and $B_{c1}$ mesons. These new results will not only improve theoretical predictions for purely leptonic $B_c$ decays, but also strengthen unitarity constraints on $b \to c$ form factors, thereby improving the precision of predictions for $\bar{B} \to D^{(*)} \ell \barν$ decays and the determination of $|V_{cb}|$.

hep-ph↗

arXiv2025

Subatomic Heroes

Sharing the amazing achievements of the (particle) physics world with the general public is at the heart of the mission of the Subatomic Heroes, based at the University of Siegen, Germany. Originally this started out as an endeavor of theoretical particle physics, now we are steadily spreading out to cover and include more branches of physics and science. Our activities range from merging art with public physics lectures via marvelous artistic performances at the local theater, over dedicated events for high-school students, to our Subatomic Heroes channel on Instagram and TikTok where you may also find out when and where our famous "hadronic ice-cream" will be served next! So follow us on https://www.instagram.com/subatomic_heroes and https://www.tiktok.com/@subatomic_heroes.

physics.ed-ph↗

arXiv2025

HQET sum rules for matrix elements of dimension-six four-quark operators for meson lifetimes within and beyond the Standard Model

Theory predictions of heavy-hadron lifetime ratios critically depend on precise determinations of the dimension-six spectator effects arising from the double insertion of the weak effective $|ΔB| = 1$ Hamiltonian. In the presence of beyond-standard-model (BSM) operators, the resulting $ΔB = 0$ Hamiltonian features additional four-quark operators whose matrix elements need to be determined using non-perturbative methods. We present for the first time results for the non-perturbative hadronic matrix elements of the four-quark operators relevant for the description of the meson lifetime ratio $τ\left(B^+\right) / τ\left(B_d\right)$, obtained using heavy-quark effective theory (HQET) sum rules with the full BSM effective Hamiltonian. In addition, we recompute and update the bag parameters for the Standard Model operators.

hep-ph↗

arXiv2024

Constraining $B$-Mesogenesis models with inclusive and exclusive decays

The $B$-Mesogenesis model explains the matter-antimatter asymmetry and leads to the right amount of dark matter in the Universe. In particular, this model predicts new decay channels of the $b$ quark. We investigate the modification of inclusive $b$-hadron decay rates and of the lifetimes of different $B$ mesons due to these new decay channels and compare our results with available predictions for exclusive $B$ meson decays. We find a small surviving parameter space where the $B$-Mesogenesis model is working and which has not been excluded by experiment. Experimental investigations in the near future should be able to test this remaining parameter space and thus either exclude or confirm the $B$-Mesogenesis model.

hep-ph↗