Mon·Sep 13, 2021Monday·September 13, 2021

1. 01*

   The hadronic contribution to the running of the electromagnetic coupling and electroweak mixing angle

   Teseo San José🇩🇪 · Marco Cè🇨🇭 · Antoine Gérardin🇫🇷 · Georg von Hippel🇩🇪 · Harvey B. Meyer🇩🇪 · Kohtaroh Miura🇩🇪 · Konstantin Ottnad🇩🇪 · Andreas Risch🇩🇪 · Jonas Wilhelm🇩🇪 · Hartmut Wittig🇩🇪

   As present and future experiments, on both the energy and precision frontiers, look to identify new physics beyond the Standard Model, we require more precise determinations of fundamental quantities, like the QED and electroweak couplings at various momenta. These can be obtained either entirely from experimental measurements, or from one such measurement at a particular virtuality combined with the couplings' virtuality dependence computed within the SM. Thus, a precise, entirely theoretical determination of the running couplings is highly desirable, even more since the preliminary results of the E989 experiment in Fermilab were published. We give results for the hadronic contribution to the QED running coupling $\alpha (Q^2)$ and weak mixing angle ${\sin }^2{\theta }_W(Q^2)$ in the space-like energy region $(0,7]{\text{GeV}}^2$ with a total relative uncertainty of $2\%$ at energies $Q^2\ll 1{\text{GeV}}^2$, and $1\%$ at $Q^2>1{\text{GeV}}^2$.

   hep-lathep-phPoS(2022)·2 citations
2. 02*

   Exploring the 3D Ising gauge-Higgs model in exact Coulomb gauge and with a gauge-invariant substitute for Landau gauge

   Michael Grady🇺🇸

   The Z2 gauge-Higgs model in three dimensions has two different types of phase transition, confinement-deconfinement and Higgs magnetization. Here they are explored through two order parameters, the Coulomb magnetization which is a local order parameter for confinement, and a replica-based gauge-invariant order parameter which tracks the Higgs transition in a way similar to Landau-gauge magnetization. Minimal Coulomb gauge is set exactly, using the polynomial-time minimum-weight matching algorithm of Edmonds. This is a tremendous speed improvement over relaxation/annealing methods and completely eliminates the systematic error. The replica-overlap is also an improvement over relaxation methods for setting Landau gauge, in that it has an easily controllable and measurable systematic error. These simulations show the phase transitions not ending at the first-order endpoint but bifurcating near there and continuing even through the expected analyticity region. The specific heat critical exponents, $\alpha$, are highly negative, explaining the lack of strong signals in the energy. Nevertheless, energy moments are seen to follow curves consistent with the predictions from the order parameters, showing these to be true thermal transitions, albeit weak ones. These results cast further doubt on Fradkin-Shenker analyticity. They also suggest one or more new yet to be explored phases in gauge-Higgs models in the bifurcated region.

   hep-lat6 citations
3. 03*

   Charm (and bottom) baryons and charmonium excitations from the lattice

   M. Padmanath🇩🇪

   This report discusses some recent investigations of the heavy hadron spectra using lattice QCD. The first half addresses multiple precision determinations of the masses of charm (and bottom) baryons. Recent lattice results in the tetraquark and the dibaryon sectors are also presented. The second half focuses on new exploratory studies of the excited charmonium spectra in the vector and scalar channels. Along the way, lattice results are compared with the experimental results, wherever they are available.

   hep-lathep-exhep-phPoS(2021)·3 citations
4. 04*

   Relativistic, model-independent determination of electromagnetic finite-size effects beyond the point-like approximation

   M. Di Carlo🇬🇧 · M. T. Hansen🇬🇧 · N. Hermansson-Truedsson🇨🇭 · A. Portelli🇬🇧

   We present a relativistic and model-independent method to derive structure-dependent electromagnetic finite-size effects. This is a systematic procedure, particularly well-suited for automatization, which works at arbitrarily high orders in the large-volume expansion. Structure-dependent coefficients appear as zero-momentum derivatives of physical form factors which can be obtained through experimental measurements or auxiliary lattice calculations. As an application we derive the electromagnetic finite-size effects on the pseudoscalar meson mass and leptonic decay amplitude, through orders $\mathcal{O}(1/L^3)$ and $\mathcal{O}(1/L^2)$, respectively. The structure dependence appears at this order through the meson charge radius and the real radiative leptonic amplitude, which are known experimentally.

   hep-lathep-phhep-thPRD(2022)·29 citations
5. 05*

   More on the Weak Gravity Conjecture via Convexity of Charged Operators

   Oleg Antipin🇭🇷 · Jahmall Bersini🇭🇷 · Francesco Sannino🇩🇰 · Zhi-Wei Wang🇩🇰 · Chen Zhang🇮🇹

   The Weak Gravity Conjecture has recently been re-formulated in terms of a particle with non-negative self-binding energy. Because of the dual conformal field theory (CFT) formulation in the anti-de Sitter space the conformal dimension $\Delta (Q)$ of the lowest-dimension operator with charge Q under some global U(1) symmetry must be a convex function of Q. This property has been conjectured to hold for any (unitary) conformal field theory and generalized to larger global symmetry groups. Here we refine and further test the convex charge conjecture via semiclassical computations for fixed charge sectors of different theories in different dimensions. We analyze the convexity properties of the leading and next-to-leading order terms stemming from the semiclassical computation, de facto, extending previous tests beyond the leading perturbative contributions and to arbitrary charges. In particular, the leading contribution is sufficient to test convexity in the semiclassical computations. We also consider intriguing cases in which the models feature a transition from real to complex conformal dimensions either as a function of the charge or number of matter fields. As a relevant example of the first kind, we investigate the $O(N)$ model in $4+ϵ$ dimensions. As an example of the second type we consider the $U(N)\times U(M)$ model in $4-ϵ$ dimensions. Both models display a rich dynamics where, by changing the number of matter fields and/or charge, one can achieve dramatically different physical regimes. We discover that whenever a complex conformal dimension appears, the real part satisfies the convexity property.

   ↳ hep-thgr-qchep-lathep-phJHEP(2021)·27 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.