Fri·Oct 21, 2022Friday·October 21, 2022

1. 01*

   Chiral Symmetry Breaking in QED induced by an External Magnetic Field

   D. K. Sinclair🇺🇸 · J. B. Kogut🇺🇸

   We simulate Lattice QED in a constant external magnetic field using the RHMC algorithm. We seek evidence for chiral symmetry breaking predicted by truncated Schwinger-Dyson methods. Since the predicted values of the dynamical electron mass and chiral condensate at the physical fine structure constant are too small to be measured, we simulate at a larger value $\alpha =1/5$. This requires using electron masses as low as $m=0.001$ to extrapolate to $m=0$. At a large magnetic field, the electrons occupy the lowest Landau level which has a small profile in the plane orthogonal to the magnetic field, so that we are able to use a lattice with small extent in these 2 directions. If chiral symmetry is unbroken at $m=0$ the chiral condensate is dominated by large momenta and should be insensitive to the lattice extent in the direction of the magnetic field and the time direction. When chiral symmetry is broken at $m=0$, the chiral condensate should be sensitive to the lattice size in these directions as $m\to 0$. We search for this behaviour by increasing the lattice extent in these 2 directions. Preliminary simulations show strong dependence of the chiral condensate on the lattice extent in these 2 directions for the smallest masses, and these increased condensates appear to be approaching a non-zero limit as $m\to 0$.

   hep-latPoS(2023)·1 citation
2. 02*

   The search for new physics in $B\to K{\ell }^{+}{\ell }^{-}$ and $B\to K\nu \bar{\nu }$ using precise lattice QCD form factors

   W. G. Parrott🇬🇧 · C. Bouchard🇬🇧 · C. T. H. Davies🇬🇧

   We present HPQCD's improved scalar, vector and tensor form factors for $B\to K$ semileptonic decays, using the heavy-HISQ formalism for more accurate normalisation of the weak currents. Working with masses close to the physical $b$ on the finest ensemble and including three ensembles with physical light quarks, we cover the full physical $q^2$ range with good precision. Our uncertainties at $q^2=0$ are a factor of three better than earlier work. We compare Standard Model observables using our form factors to experimental measurements for the rare flavour changing neutral current processes $B\to K{\ell }^{+}{\ell }^{-}$ and $B\to K\nu \bar{\nu }$ and discuss the significance of the tensions that arise.

   hep-lathep-phPoS(2023)·10 citations
3. 03*

   A New Type of Lattice Gauge Theory through Self-adjoint Extensions

   A. Banerjee · D. Banerjee · G. Kanwar🇨🇭 · A. Mariani🇨🇭 · T. Rindlisbacher🇨🇭 · U.J. Wiese🇨🇭

   A generalization of Wilsonian lattice gauge theory may be obtained by considering the possible self-adjoint extensions of the electric field operator in the Hamiltonian formalism. In the special case of 3D $\mathrm{U}(1)$ gauge theory these are parametrised by a phase $\theta$, and the ordinary Wilson theory is recovered for $\theta =0$. We consider the case $\theta =\pi$, which, upon dualization, turns into a theory of staggered integer and half-integer height variables. We investigate order parameters for the breaking of the relevant symmetries, and thus study the phase diagram of the theory, which shows evidence of a broken ${\mathbb{Z}}_2$ symmetry in the continuum limit, in contrast to the ordinary theory.

   hep-latPoS(2023)·0 citations
4. 04*

   Singlet Mesons in Dark $Sp(4)$ Theories

   Fabian Zierler🇦🇹 · Jong-Wan Lee🇰🇷 · Axel Maas🇦🇹 · Felix Pressler🇦🇹

   We explore some aspects of $Sp(4)$ gauge theory with two fundamental fermions in the context of composite Goldstone Dark Matter. We present preliminary lattice results for the mass of the pseudoscalar iso-singlet meson ${\eta }^{\prime }$ using unimproved Wilson fermions and the standard plaquette action. We find that the ${\eta }^{\prime }$ is slightly heavier than the pseudoscalar non-singlets $\pi$ and lighter than the vector mesons $\rho$ for multiple ensembles with $m_{\pi }/m_{\rho }\ge 0.77$. This pattern is potentially relevant for Beyond the Standard Model physics model building. Furthermore, we show that for $N_f=1+1$ flavours the disconnected contributions to the unflavoured pseudoscalar ${\pi }^0$ are small. We supplement this measurement by a calculation of the $\pi \pi$ scattering length $a_0$ which shows that the ensemble studied might be phenomenologically relevant for Dark Matter models such as the Strongly Interacting Massive Particles paradigm.

   hep-lathep-phPoS(2023)·11 citations
5. 05*

   Topology changing update algorithms for SU(3) gauge theory

   Timo Eichhorn🇩🇪 · Christian Hoelbling🇩🇪 · Philip Rouenhoff🇩🇪 · Lukas Varnhorst🇩🇪

   At fine lattice spacings, lattice simulations are plagued by slow (topological) modes that give rise to large autocorrelation times. These, in turn, lead to statistical and systematic errors that are difficult to estimate. We study the problem and possible algorithmic solutions in 4-dimensional SU(3) gauge theory, with special focus on instanton updates and Metadynamics.

   hep-latPoS(2023)·11 citations
6. 06*

   Measurement-based quantum simulation of Abelian lattice gauge theories

   Hiroki Sukeno🇺🇸 · Takuya Okuda🇯🇵

   Numerical simulation of lattice gauge theories is an indispensable tool in high energy physics, and their quantum simulation is expected to become a major application of quantum computers in the future. In this work, for an Abelian lattice gauge theory in $d$ spacetime dimensions, we define an entangled resource state (generalized cluster state) that reflects the spacetime structure of the gauge theory. We show that sequential single-qubit measurements with the bases adapted according to the former measurement outcomes induce a deterministic Hamiltonian quantum simulation of the gauge theory on the boundary. Our construction includes the $(2+1)$-dimensional Abelian lattice gauge theory simulated on three-dimensional cluster state as an example, and generalizes to the simulation of Wegner's lattice models $M_{(d,n)}$ that involve higher-form Abelian gauge fields. We demonstrate that the generalized cluster state has a symmetry-protected topological order with respect to generalized global symmetries that are related to the symmetries of the simulated gauge theories on the boundary. Our procedure can be generalized to the simulation of Kitaev's Majorana chain on a fermionic resource state. We also study the imaginary-time quantum simulation with two-qubit measurements and post-selections, and a classical-quantum correspondence, where the statistical partition function of the model $M_{(d,n)}$ is written as the overlap between the product of two-qubit measurement bases and the wave function of the generalized cluster state.

   ↳ quant-phcond-mat.str-elhep-lathep-thSciPost Phys.(2023)·13 citations
7. 07*

   Partial deconfinement: a brief overview

   Masanori Hanada🇬🇧 · Hiromasa Watanabe🇯🇵

   The confinement/deconfinement transition in gauge theory plays important roles in physics, including the description of thermal phase transitions in the dual gravitational theory. Partial deconfinement implies an intermediate phase in which color degrees of freedom split into the confined and deconfined sectors. The partially-deconfined phase is dual to the small black hole that lies between the large black hole and graviton gas. Better understandings of partial deconfinement may provide us with a clue how gravity emerges from the field theory degrees of freedom. In this article, we briefly review the basic properties of partial deconfinement and discuss applications.

   ↳ hep-thhep-latEur.Phys.J.ST(2023)·10 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.