Publications

Order by: publication date number of citations

• Searching for muon to electron conversion: The Mu2e experiment at Fermilab

  Richard Bonventre on behalf of the Mu2e Collaboration

  SciPost Phys. Proc. 1, 038 (2019) · published 21 February 2019 | Toggle abstract · pdf

  The Mu2e experiment will measure the charged-lepton flavor violating (CLFV) neutrino-less conversion of a negative muon into an electron in the field of a nucleus. Mu2e will improve the previous measurement by four orders of magnitude, reaching a 90% C.L. limit of $8\times10^{-17}$ on the conversion rate. The experiment will reach mass scales of nearly $10^4$ TeV, far beyond the direct reach of colliders. The experiment is sensitive to a wide range of new physics, complementing and extending other CLFV searches. Mu2e is under design and construction at the Muon Campus of Fermilab; we expect to start taking physics data in 2022 with 3 years of running to achieve our target sensitivity.

  4 citations

• The search for the neutron electric dipole moment at PSI

  Guillaume Pignol, Philipp Schmidt-Wellenburg

  SciPost Phys. Proc. 5, 027 (2021) · published 6 September 2021 | Toggle abstract · pdf

  The existence of a nonzero permanent electric dipole moment (EDM) of the neutron would reveal a new source of CP violation and shed light on the origin of the matter--antimatter asymmetry of the Universe. The sensitivity of current experiments using stored ultracold neutrons (UCN) probes new physics beyond the TeV scale. Using the UCN source at the Paul Scherrer Institut, the nEDM collaboration has performed the most sensitive measurement of the neutron EDM to date, still compatible with zero ($|d_n|<1.8\times 10^{-26} \, e {\rm cm}$, C.L.90%). A new experiment designed to improve the sensitivity by an order of magnitude, n2EDM, is currently in construction.

  4 citations

• Muonium-Antimuonium Conversion

  Lorenz Willmann, Klaus Jungmann

  SciPost Phys. Proc. 5, 009 (2021) · published 6 September 2021 | Toggle abstract · pdf

  The MACS experiment performed at PSI in the 1990s provided an yet unchallenged upper bound on the probability for a spontaneous conversion of the muonium atom, ${\rm M=}$($\rm{\mu^+e^-}$) , into its antiatom, antimuonium ${\overline{\rm{M}} = }$($\rm{\mu^-e^+})$. It comprises the culmination of a series of measurements at various accelerator laboratories worldwide. The experimental limits on the process have provided input and steering for the further development of a variety of theoretical models beyond the standard theory, in particular for models which address lepton number violating processes and matter-antimatter oscillations. Several models beyond the standard theory could be strongly disfavored. There is interest in a new measurement and improved sensitivity could be reached by exploiting the time evolution of the conversion process, e.g., at intense pulsed muonium sources.

  4 citations

• Two-parton scattering in the high-energy limit: climbing two- and three-Reggeon ladders

  G. Falcioni, E. Gardi, N. Maher, C. Milloy, L. Vernazza

  SciPost Phys. Proc. 7, 007 (2022) · published 20 June 2022 | Toggle abstract · pdf

  We review recent progress on the calculation of scattering amplitudes in the high-energy limit. We start by illustrating the shockwave formalism, which allows one to calculate amplitudes as iterated solutions of rapidity evolution equations. We then focus on our recent results regarding 2 -> 2 parton scattering. We present the calculation of the imaginary part of the amplitude, at next-to-leading logarithmic accuracy in the high-energy logarithms, formally to all orders, and in practice to 13 loops. We then discuss the computation of the real part of the amplitude at next-to-next-to-leading logarithmic accuracy and through four loops. Both computations are carried in full colour, and provide new insight into the analytic structure of scattering amplitudes and their infrared singularity structure.

  4 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.

  4 citations

• Two-loop gauge coupling $β$-function in a four-dimensional framework: the Standard Model case

  Adriano Cherchiglia

  SciPost Phys. Proc. 7, 043 (2022) · published 22 June 2022 | Toggle abstract · pdf

  At present, the gauge coupling $\beta$-function in the Standard Model (SM) is known up to four-loop order. As most SM calculations, dimensional regularization was employed. Despite its striking success, other regularization schemes have emerged, which aim to stay in the physical dimension as far as possible. In this contribution, we apply Implicit Regularization, a scheme defined in momentum space that complies with BPHZ, to obtain the two-loop gauge coupling $\beta$-function in the Standard Model. We reproduce the same result obtained when applying dimensional regularization.

  4 citations

• LUXE: A new experiment to study non-perturbative QED in $e^{-}$-laser and $γ$-laser collisions

  Ruth Jacobs

  SciPost Phys. Proc. 8, 088 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The LUXE experiment (Laser Und XFEL Experiment) is a new experiment in planning at DESY Hamburg using the electron beam of the European XFEL. LUXE is intended to study collisions between a high-intensity optical laser and up to 16.5 GeV electrons from the Eu.XFEL electron beam, or, alternatively, high-energy secondary photons. The physics objective of LUXE are processes of Quantum Electrodynamics (QED) at the strong-field frontier, where QED is non-perturbative. This manifests itself in the creation of physical electron-positron pairs from the QED vacuum. LUXE intends to measure the positron production rate in a new physics regime at an unprecedented laser intensity. Parasitically, the high-intensity Compton photon beam of LUXE can be used to search for physics beyond the Standard Model.

  3 citations

• The LHCspin project

  M. Santimaria, V. Carassiti, G. Ciullo, P. Di Nezza, P. Lenisa, S. Mariani, L. L. Pappalardo, E. Steffens

  SciPost Phys. Proc. 8, 050 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Broad and unexplored kinematic regions can be accessed at the LHC with fixed-target $pp$, $pA$ and $PbA$ collisions at $\sqrt{s_{\rm{NN}}}=72-115~\rm{GeV}$. The LHCb detector is a fully-instrumented forward spectrometer able to run in fixed-target mode, and currently hosts a target gas cell to take data in the upcoming Run 3. The LHCspin project aims at extending this physics program to Run 4 and to bring polarised physics at the LHC. An overview of the physics potential and a description of the LHCspin experimental setup are presented.

  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

• Three-body correlations in mesonic-atom-like systems

  Hajime Moriya, Wataru Horiuchi, Jean-Marc Richard

  SciPost Phys. Proc. 3, 051 (2020) · published 27 February 2020 | Toggle abstract · pdf

  Three-body correlations in three-body exotic atoms are studied with simple models that consist of three bosons interacting through a superposition of long- and short-range potentials. We discuss the correlations among particles by comparing the energy shifts given by precise three-body calculations and by the Deser-Trueman formula, in which the long- and short-range contributions are factorized. By varying the coupling of the short-range potential, we evaluate the ranges of the strength where the two-body correlations dominate and where the three-body correlations cannot be neglected.

  3 citations