Publications

Order by: publication date number of citations

• $\mathcal{O}(α_s^3)$ corrections to semileptonic $b \to c$ decays in the heavy daughter approximation

  Kay Schoenwald

  SciPost Phys. Proc. 7, 027 (2022) · published 21 June 2022 | Toggle abstract · pdf

  We present our recent calculation of the third order corrections to the semileptonic $b \to c$ and the muon decays. The calculation has been performed in an expansion around the limit $m_c \sim m_b$, but shows decent convergence even for $m_c=0$ from which the contribution to the muon decay can be extracted. For the semileptonic $b \to c$ decay we find large perturbative corrections in the on-shell scheme which can be significantly reduced by changing to the kinetic scheme for the bottom quark mass. These results are important input for the inclusive determination of $|V_{cb}|$ and the Fermi coupling constant $G_F$.

• Generating the electro-weak scale by vector-like quark condensation

  Sophie Klett, Manfred Lindner, Andreas Trautner

  SciPost Phys. 14, 076 (2023) · published 19 April 2023 | Toggle abstract · pdf

  We show that vector-like quarks in the fundamental or higher-dimensional representations of QCD can generate the electro-weak scale in a phenomenologically viable way by chiral symmetry breaking condensates. The thereby generated scales are determined by numerically solving the Dyson-Schwinger equation and these scales are sizable, because they grow with the hard vector-like mass. Communicating such a scale to the Standard Model via a conformally invariant scalar sector can dynamically generate the electro-weak scale without a naturalness problem, because all non-dynamical mass scales are protected by chiral symmetry. We present a minimal setup which requires only a new neutral scalar with mass not too far above the electro-weak scale, as well as vector-like quarks at the (multi-)TeV scale. Both are consistent with current bounds and are attractive for future experimental searches at the LHC and future colliders. Depending on the hypercharge of the vector-like quarks, hadrons made of them are color-neutral bound states which would be interesting Dark Matter candidates.

• Higher-order corrections to the kinetic mass definition for the bottom and the charm quarks

  Matteo Fael

  SciPost Phys. Proc. 7, 026 (2022) · published 21 June 2022 | Toggle abstract · pdf

  In these proceedings we discuss the relation between the kinetic and the on-shell schemes for the bottom and the charm quarks and present the methods for the calculation of the mass relation to higher orders in perturbative QCD. The bottom mass in the kinetic scheme is a pivotal input parameter in the inclusive determination of $|V_{cb}|$ from $B\to X_c \ell \nu_\ell$ decays. By combining the relation between the kinetic and the on-shell mass with well-know results for the $\overline{\mathrm{MS}}$-on-shell conversion, we obtain a prediction for $m_b^\mathrm{kin}$ based on precise determinations of $\overline{m}_b(\overline{m}_b)$.

• Towards two- and three-loop QCD corrections to the width difference in $B_s-\bar{B}_s$ mixing

  Vladyslav Shtabovenko

  SciPost Phys. Proc. 7, 025 (2022) · published 21 June 2022 | Toggle abstract · pdf

  In this work we address the issue of large perturbative uncertainties in the theory prediction for $\Delta \Gamma_s$, the width difference in the $B^0_s - \bar{B}^0_s$ mixing process. To this aim we complete important steps towards the full analytic result for the previously unknown Wilson coefficients from the matching between $|\Delta B|=1$ and $|\Delta B|=2$ effective Hamiltonians at next-to-next-leading order (NNLO) in the strong coupling constant. We provide a thorough discussion of technical and conceptual difficulties behind this computation and give an outlook regarding the availability of the new NNLO theory prediction for $\Delta \Gamma_s$.

• Chiral gauge theories on $R^3 \times S^1$ and SUSY breaking

  Jun Seok Lee, John Terning

  SciPost Phys. 14, 081 (2023) · published 24 April 2023 | Toggle abstract · pdf

  We study $SU(5)$ chiral gauge theories on $R^3\times S^1$. With an unequal number of fundamental and antifundmental matter representations we calculate nontrivial pre-ADS superpotentials generated by composite multi-monopoles. We also point out that the structure of the composite multi-monopoles can be determined simply from the affine Dynkin diagrams of the gauge group and its unbroken subgroup. For the case of one flavor, we find that the superpotential is independent of the composite meson. We show that dynamical 4D SUSY breaking in the simplest chiral $SU(5)$ gauge theory can be demonstrated directly via semi-classical effects on the circle.

• Eikonal Dressed Gluon Exponentiation to study power corrections to Thrust, C-parameter, and Angularity

  Neelima Agarwal, Ayan Mukhopadhyay, Sourav Pal, Anurag Tripathi

  SciPost Phys. Proc. 7, 020 (2022) · published 21 June 2022 | Toggle abstract · pdf

  Dressed Gluon Exponentiation is a well known method to study power corrections. We present here its eikonalized version -- Eikonal Dressed Gluon Exponentiation (EDGE) \cite{Agarwal:2020uxi} to determine the dominant power corrections to shape variables such as Thrust, $ C $- parameter, and Angularity. Our method remarkably simplifies the calculations.

• Leading fermionic three-loop corrections to W-boson mass and Z-pole observables

  Lisong Chen, Ayres Freitas

  SciPost Phys. Proc. 7, 019 (2022) · published 21 June 2022 | Toggle abstract · pdf

  In this proceeding, we highlight the computation of leading fermionic three-loop corrections to electroweak precision observables (EWPOs) accomplished recently. We summarize the numerical analysis and provide an outlook.

• New developments in KKMChh: Quark-level exponentiated radiative corrections and semi-analytical results

  S.A. Yost, M. Dittrich, S. Jadach, B.F.L. Ward, Z. Wąs

  SciPost Phys. Proc. 7, 016 (2022) · published 20 June 2022 | Toggle abstract · pdf

  We describe a new semi-analytical program, KKhhFoam, which provides a simplified framework for testing the amplitude-level exponentiation scheme (CEEX) of the full KKMChh program in the semi-soft limit. The structure of the KKhhFoam integrand is also helpful for elucidating the structure of CEEX. We also discuss the representation of ISR in KKMChh and compare the ISR added by KKMChh to the effect of switching to a QED-corrected PDF, at the individual quark level, and suggest a new approach to running KKMChh with QED-corrected PDFs.

• IR-Improved Amplitude-Based Resummation in Quantum Field Theory: New Results and New Issues

  B.F.L. Ward, S. Jadach, W. Placzek, M. Skrzypek, Z. Was, S. A. Yost

  SciPost Phys. Proc. 7, 015 (2022) · published 20 June 2022 | Toggle abstract · pdf

  With the advancement of strategies for the precision physics programs for the HL-LHC, FCC-ee, FCC-hh, ILC, CLIC, CEPC, and CPPC, the need for proper control of the attendant theoretical precision tags is manifest. We discuss the role that amplitude-based resummation may play in this regard with examples from the LHC, the proposed new colliders and quantum gravity.