Publications

Order by: publication date number of citations

• On the spin content of the classical massless Rarita-Schwinger system

  Mauricio Valenzuela, Jorge Zanelli

  SciPost Phys. Proc. 14, 047 (2023) · published 24 November 2023 | Toggle abstract · pdf

  We analyze the Rarita-Schwinger massless theory in the Lagrangian and Hamiltonian approaches. At the Lagrangian level, the standard gamma-trace gauge fixing constraint leaves a 1/2 and a 3/2 propagating Poincaré group helicities. At the Hamiltonian level, the result depends on whether the Dirac conjecture is assumed or not. In the affirmative case, a secondary first class constraint is added to the total Hamiltonian and a corresponding gauge fixing condition must be imposed, completely removing the 1/2 sector. In the opposite case, the 1/2 field propagates and the Hamilton field equations match the Euler-Lagrange equations.

  3 citations

• Magnetic properties of the putative higher-order topological insulator EuIn$_2$As$_2$

  Tomasz Toliński, Dariusz Kaczorowski

  SciPost Phys. Proc. 11, 005 (2023) · published 5 June 2023 | Toggle abstract · pdf

  In higher-order topological insulator (HOTI), a gap is preserved both for the bulk and the surface states, and only hinges or corners become gapless. Recently, it has been predicted that the antiferromagnetic compound EuIn$_2$As$_2$ can host both the HOTI and axion insulator features. Preliminary experimental confirmation of this finding was obtained using angle-resolved photoemission spectroscopy. The main objective of this work was to characterize the anisotropic magnetic properties of single-crystalline EuIn$_2$As$_2$. In addition, complementary studies on the transport properties, heat capacity, and magnetocaloric effect in this compound were performed.

  3 citations

• Particle representation for $NN{\bar K}$ system

  Branislav Vlahovic, Igor Filikhin, Roman Ya. Kezarashvili

  SciPost Phys. Proc. 3, 044 (2020) · published 27 February 2020 | Toggle abstract · pdf

  In the framework of the Faddeev equations in configuration space we perform an analysis of quasi-bound state of the $NN{\bar K}$ system within a particle model. In our approach, the system $NN{\bar K}(s_{NN}=0)$ ($NN{\bar K}(s_{NN}=1))$ is described as a superposition of $ppK^{-}$ and $pn{\bar K}^0$ ($nn{\bar K}^{0}$ and $pn{ K}^-$) states, which is possible due to a particle transition. The relation of the particle model to the theory of a two-state quantum system is addressed and discussed taking into account the possibilities of deep and shallow $NN{\bar K}(s_{NN}=0)$ quasi-bound states.

  3 citations

• The MSHT20 Parton Distribution Functions

  R.S. Thorne, S. Bailey, T. Cridge, L. Harland-Lang, A.D. Martin

  SciPost Phys. Proc. 8, 018 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present the new MSHT20 set of parton distribution functions (PDFs) of the proton, determined from a global analysis of the available hard scattering data and superseding the MMHT14 sets. The parameterisation is now adapted and extended and we include a large number of new data sets: the final HERA and Tevatron data, and a significant number of LHC data sets on vector boson production, inclusive jets and top quark distributions. We include up to NNLO QCD corrections for all data sets that play a major role in the fit. There are some changes to central PDF values and a significant reduction in the uncertainties, but the PDFs and the predictions using them are generally within one standard deviation of the MMHT14 results. We discuss the phenomenological impact of our results.

  3 citations

• Hadron structure from basis light-front quantization

  Chandan Mondal, Jiangshan Lan, Kaiyu Fu, Siqi Xu, Zhi Hu, Xingbo Zhao, James P. Vary

  SciPost Phys. Proc. 10, 036 (2022) · published 11 August 2022 | Toggle abstract · pdf

  We present our recent progress in applying basis light-front quantization approach to investigate the structure of the light mesons and the nucleon.

  3 citations

• The Mu3e experiment

  F. Wauters on behalf of the Mu3e collaboration

  SciPost Phys. Proc. 5, 020 (2021) · published 6 September 2021 | Toggle abstract · pdf

  The \emph{Mu3e} experiment aims for a single event sensitivity of 2$\cdot$10$^{-15}$ on the charged lepton flavour violating $\mu^+\rightarrow e^+ e^+ e^-$ decay. The experimental apparatus, a light-weight tracker based on custom High-Voltage Monolithic Active Pixel Sensors placed in a 1~T magnetic field is currently under construction at the Paul Scherrer Institute, where it will use the full intense 10$^8$ $\mu^+$/s beam available. A final sensitivity of 1$\cdot$10$^{-16}$ is envisioned for a phase II experiment, driving the development of a new high-intensity DC muon source.

  3 citations

• QED in the clothed-particle representation: a fresh look at positronium properties treatment

  Yan A. Kostylenko, Adam M. Arslanaliev, Aleksandr V. Shebeko

  SciPost Phys. Proc. 3, 045 (2020) · published 27 February 2020 | Toggle abstract · pdf

  We have extended our previous applications of the method of unitary clothing transformations (UCTs) in mesodynamics [1, 2] to quantum electrodynamics (QED) [3, 4]. An analytical expression for the QED Hamiltonian in the clothed-particle representation (CPR) has been derived. Its distinctive feature is the appearance of a new family of the Hermitian and energy independent interaction operators built up in the e^2-order for the clothed electrons and positrons instead the primary canonical interaction between electromagnetic and electron-positron fields. The problem of describing the bound states in QED in case of the positronium system has been considered. The first correction to the energy of the ground state of the para-positronium and its decay rate to two photons has been calculated by using the new interaction operators.

  3 citations

• MEG: Muon to Electron and Gamma

  A.M. Baldini, T. Mori

  SciPost Phys. Proc. 5, 019 (2021) · published 6 September 2021 | Toggle abstract · pdf

  The possible existence of the muon to electron and gamma decay predicted by many new physics scenarios is investigated by stopping positive muons in a very thin target and measuring emitted photons and positrons with the best possible resolutions. Photons are measured by a 2.7 ton ultra pure liquid xenon detector while positron trajectories are measured in a specially designed gradient magnetic field by low-mass drift chambers and precisely timed by scintillation counters. A first phase of the experiment (MEG) ended in 2016, and excluded the existence of the decay with branching ratios larger than 4.2x10**(-13) (90% C.L.). This provides approximately 30 times stronger constraints on a variety of new physics models than previous experiments. In the second phase (MEG II), most of the detectors have been upgraded by adopting up-to-date technologies to improve the search sensitivity by another order of magnitude down to O(10**(-19) ). MEG II will pursue new physics beyond the Standard Model complementary to high energy collider experiments with a compatible or even higher sensitivity.

  3 citations

• Measurement of Intermittency for Charged Particles in Au + Au Collisions at $\sqrt{s_\mathrm{NN}}$ = 7.7-200 GeV from STAR

  Jin Wu

  SciPost Phys. Proc. 10, 041 (2022) · published 11 August 2022 | Toggle abstract · pdf

  Local density fluctuations near the QCD critical point can be probed by intermittency analysis of scaled factorial moments in relativistic heavy-ion collisions. We report the first measurement of intermittency for charged particles in Au + Au collisions at $\sqrt{s_\mathrm{NN}}$ = 7.7-200 GeV from the STAR experiment at RHIC. We observe scaling behaviors in central Au + Au collisions, with the extracted scaling exponent decreasing from mid-central to the most central Au + Au collisions. Furthermore, the scaling exponent exhibits a non-monotonic energy dependence with a minimum around $\sqrt{s_\mathrm{NN}}$ = 20-30 GeV in central Au + Au collisions.

  3 citations

• A contribution of the HAWC observatory to the TeV era in the high energy gamma-ray astrophysics: The case of the TeV-halos

  Ramiro Torres-Escobedo, Hao Zhou, Eduardo de la Fuente for the HAWC Collaboration

  SciPost Phys. Proc. 13, 029 (2023) · published 29 September 2023 | Toggle abstract · pdf

  We present a short overview of the TeV-Halos objects as a discovery and a relevant contribution of the High Altitude Water Çerenkov (HAWC) observatory to TeV astrophysics. We discuss history, discovery, knowledge, and the next step through a new and more detailed analysis than the original study in 2017. TeV-Halos will contribute to resolving the problem of the local positron excess observed on the Earth. To clarify the latter, understanding the diffusion process is mandatory.

  3 citations