Publications

Order by: publication date number of citations

• Measurement of the transverse polarization of electrons emitted in neutron decay – nTRV experiment

  K. Bodek, A. Kozela

  SciPost Phys. Proc. 5, 015 (2021) · published 6 September 2021 | Toggle abstract · pdf

  This paper recalls the main achievements of the nTRV experiment which measured two components of the transverse polarization ($\sigma_{T_{1}}$, $\sigma_{T_{2}}$) of electrons emitted in the $\beta$-decay of polarized, free neutrons and deduced two correlation coefficients, $R$ and $N$, that are sensitive to physics beyond the Standard Model. The value of time-reversal odd coefficient $R$, 0.004$\pm$0.012$\pm$0.005, significantly improved limits on the relative strength of imaginary scalar coupling constant in the weak interaction. The value obtained for the time-reversal even correlation coefficient $N$, 0.067$\pm$0.011$\pm$0.004, agrees with the Standard Model expectation, providing an important sensitivity test of the electron polarimeter. One of the conclusions of this pioneering experiment was that the transverse electron polarization in the neutron $\beta$-decay is worth more systematic exploring by measurements of yet experimentally not attempted correlation coefficients such as $H$, $L$, $S$, $U$ and $V$. This article presents a brief outlook on that questions.

• Differential measurements of jet sub-structure observables and their correlation in p+p collisions at √s = 200 GeV in STAR

  Monika Robotková

  SciPost Phys. Proc. 8, 071 (2022) · published 12 July 2022 | Toggle abstract · pdf

  This analysis extends recent measurements of the jet sub-structure observables based on the SoftDrop algorithm in p+p collisions at √s = 200 GeV in the STAR experiment. We present fully unfolded multi-differential measurements of jet sub-structure observables at the first split and their correlations for jets of different transverse momenta and radii. We compare our measurements to various Monte Carlo models.

• Recent Studies of Exotic Hadrons at the LHCb Experiment

  Gary Robertson

  SciPost Phys. Proc. 8, 030 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Recent results on studies of exotic hadrons at the LHCb experiment are summarised. These are the observation of new resonances decaying to J/$\psi K^{+}$ and J/$\psi\phi$, evidence of a J/$\psi\Lambda$ structure and observation of excited $\Xi^{-}$ states in the $\Xi_{b}^{-}\to J/\psi \Lambda K^{-}$ decay and the study of $B_{s}^{0}\to J/\psi\pi^{+}\pi^{-}K^{+}K^{-}$ decays.

• W+c-jet production at the LHC with NNLO QCD accuracy

  Michal Czakon, Alexander Mitov, Mathieu Pellen, Rene Poncelet

  SciPost Phys. Proc. 7, 035 (2022) · published 21 June 2022 | Toggle abstract · pdf

  In these proceedings, we highlight some aspects of the recent computation of NNLO QCD corrections for W production in association with a charm jet at the LHC. The results are presented in the form of cross sections and differential distributions and are compared to ATLAS data.

• Scaling limit of the staggered six-vertex model with $U_q\big(\mathfrak{sl}(2)\big)$ invariant boundary conditions

  Holger Frahm, Sascha Gehrmann, Gleb Andreevich Kotousov

  SciPost Phys. 16, 149 (2024) · published 5 June 2024 | Toggle abstract · pdf

  We study the scaling limit of a statistical system, which is a special case of the integrable inhomogeneous six-vertex model. It possesses $U_q\big(\mathfrak{sl}(2)\big)$ invariance due to the choice of open boundary conditions imposed. An interesting feature of the lattice theory is that the spectrum of scaling dimensions contains a continuous component. By applying the ODE/IQFT correspondence and the method of the Baxter $Q$ operator the corresponding density of states is obtained. In addition, the partition function appearing in the scaling limit of the lattice model is computed, which may be of interest for the study of nonrational CFTs in the presence of boundaries. As a side result of the research, a simple formula for the matrix elements of the $Q$ operator for the general, integrable, inhomogeneous six-vertex model was discovered, that has not yet appeared in the literature. It is valid for a certain one parameter family of diagonal open boundary conditions in the sector with the $z$-projection of the total spin operator being equal to zero.

• Spin Density Matrix Elements for Exclusive $\rho^{0}$ Meson Muoproduction at COMPASS

  W.~Augustyniak

  SciPost Phys. Proc. 8, 073 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Spin density matrix elements were extracted from COMPASS data for exclusive $\rho^{0}$ meson muoproduction on a liquid hydrogen target. The measurement cover the kinematic range of 1.0 (GeV/$c$)$^2$ $< Q^{2} <$ 10.0 (GeV/$c$)$^2$, 5.0 GeV/$c^2$ $< W <$ 17.0 GeV/$c^2$ and 0.01 (GeV/$c$)$^2$ $<p^{2}_{T} < $ 0.5 (GeV/$c$)$^2$. Here, $W$ denotes the mass of the final hadronic system, $Q^{2}$ the virtuality of the exchanged photon and $p_{T}$ the transverse momentum of the $\rho^{0}$ meson with respect to the virtual-photon direction. We observe a violation of s-channel helicity conservation for the transition $\gamma^{*}_{T} \to \rho^{0}_{L}$. Additionally, we find a dominant contribution of the natural-parity-exchange transitions.

• A lattice pairing-field approach to ultracold Fermi gases

  Florian Ehmann, Joaquín E. Drut, Jens Braun

  SciPost Phys. 16, 091 (2024) · published 3 April 2024 | Toggle abstract · pdf

  We develop a pairing-field formalism for ab initio studies of non-relativistic two-component fermions on a (d+1)-dimensional spacetime lattice. More specifically, we focus on theories where the interaction between the two components can be described by the exchange of a corresponding pairing field. The introduction of a pairing field may indeed be convenient for studies of, e.g., the finite-temperature phase structure and critical behavior of, e.g., ultracold atomic Fermi gases. Moreover, such a formalism allows to directly compute the momentum and frequency dependence of the pair propagator, from which the pair-correlation function can be extracted. For a first illustration of the application of our formalism, we compute the density equation of state and the superfluid order parameter for a gas of unpolarized fermions in (0+1) dimensions by employing the complex Langevin approach to surmount the sign problem.

• Few-body reactions investigated with the Trojan Horse Method

  Roberta Spartà, Giuseppe G. Rapisarda, Claudio Spitaleri, M. La Cognata, Rosario G. Pizzone, S. Romano, Aurora Tumino

  SciPost Phys. Proc. 3, 033 (2020) · published 26 February 2020 | Toggle abstract · pdf

  The Trojan Horse Method is an indirect method to measure reaction cross sections at energies of interest for nuclear astrophysics, exploiting the nuclei clustering properties. Here it is presented with its general features and detailed for the case of the 2H(d,p)3H and 2H(d,n)3He measurements, where interesting results for astrophysics and energy fusion power plants have been obtained.

• Exploring three-nucleon forces via three- and four-nucleon scattering

  Kimiko Sekiguchi

  SciPost Phys. Proc. 3, 029 (2020) · published 26 February 2020 | Toggle abstract · pdf

  Three-nucleon force effects in three- and four-nucleon scattering are discussed from an experimental point of view.

• Higher-form symmetry and chiral transport in real-time Abelian lattice gauge theory

  Arpit Das, Adrien Florio, Nabil Iqbal, Napat Poovuttikul

  SciPost Phys. 17, 085 (2024) · published 19 September 2024 | Toggle abstract · pdf

  We study classical lattice simulations of theories of electrodynamics coupled to charged matter at finite temperature, interpreting them using the higher-form symmetry formulation of magnetohydrodynamics (MHD). We compute transport coefficients using classical Kubo formulas on the lattice and show that the properties of the simulated plasma are in complete agreement with the predictions from effective field theories. In particular, the higher-form formulation allows us to understand from hydrodynamic considerations the relaxation rate of axial charge in the chiral plasma observed in previous simulations. A key point is that the resistivity of the plasma – defined in terms of Kubo formulas for the electric field in the 1-form formulation of MHD – remains a well-defined and predictive quantity at strong electromagnetic coupling. However, the Kubo formulas used to define the conventional conductivity vanish at low frequencies due to electrodynamic fluctuations, and thus the concept of the conductivity of a gauged electric current must be interpreted with care.