Publications

Order by: publication date number of citations

• Low-energy neutron scattering on light nuclei and $^{19}$B as a $^{17}$B-$n$-$n$ three-body system in the unitary limit

  Jaume Carbonell, Emiko Hiyama, Rimantas Lazauskas, F. Miguel Marqués

  SciPost Phys. Proc. 3, 008 (2020) · published 24 February 2020 | Toggle abstract · pdf

  We consider the evolution of the neutron-nucleus scattering length for the lightest nuclei. We show that, when increasing the number of neutrons in the target nucleus, the strong Pauli repulsion is weakened and the balance with the attractive nucleon-nucleon interaction results into a resonant virtual state in $^{18}$B. We describe $^{19}$B in terms of a $^{17}$B-$n$-$n$ three-body system where the two-body subsystems $^{17}$B-$n$ and $n$-$n$ are unbound (virtual) states close to the unitary limit. The energy of $^{19}$B ground state is well reproduced and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be extended to describe the recently discovered resonant states in $^{20,21}$B.

• Measurements and searches of Higgs boson production involving fermion couplings with the ATLAS detector

  Shigeki Hirose

  SciPost Phys. Proc. 8, 006 (2022) · published 11 July 2022 | Toggle abstract · pdf

  In the standard model, fermions acquire the mass via the Yukawa interaction. This mechanism can be tested by measuring couplings of the fermions with the Higgs boson. At the ATLAS experiment, the Higgs-fermion coupling measurements became possible thanks to the abundant dataset: the integrated luminosity of 139~fb$^{-1}$ at the centre-of-mass energy of 13~TeV as well as 25~fb$^{-1}$ at 7--8~TeV. This paper presents recent results from measurements of the Higgs boson productions in decays to a fermion pair in the final state with the ATLAS detector.

• Impact of uncertainties of unbound 10Li on the ground state of two-neutron halo 11Li

  Jagjit Singh, Wataru Horiuchi

  SciPost Phys. Proc. 3, 007 (2020) · published 24 February 2020 | Toggle abstract · pdf

  Recently, the energy spectrum of 10Li was measured upto 4.6 MeV, via one-neutron transfer reaction d(9Li, p)10Li. Considering the ambiguities on the 10Li continuum spectrum with reference to new data, we report the con guration mixing in the ground state of the two-neutron halo nucleus 11Li for two different choices of the 9Li+n potential. For the present study, we employ a three-body (core+n+n) structure model developed for describing the two-neutron halo system by explicit coupling of unbound continuum states of the subsystem (core+n), and discuss the two-neutron correlations in the ground state of 11Li.

• Goodness of fit by Neyman-Pearson testing

  Gaia Grosso, Marco Letizia, Maurizio Pierini, Andrea Wulzer

  SciPost Phys. 16, 123 (2024) · published 13 May 2024 | Toggle abstract · pdf

  The Neyman-Pearson strategy for hypothesis testing can be employed for goodness of fit if the alternative hypothesis is selected from data by exploring a rich parametrised family of models, while controlling the impact of statistical fluctuations. The New Physics Learning Machine (NPLM) methodology has been developed as a concrete implementation of this idea, to target the detection of new physical effects in the context of high energy physics collider experiments. In this paper we conduct a comparison of this approach to goodness of fit with others, in particular with classifier-based strategies that share strong similarities with NPLM. From our comparison, NPLM emerges as the more sensitive test to small departures of the data from the expected distribution and not biased towards detecting specific types of anomalies. These features make it suited for agnostic searches for new physics at collider experiments. Its deployment in other scientific and industrial scenarios should be investigated.

• Hadron Production in terms of Green's Functions in Non-Equilibrium Matter

  A. V. Koshelkin

  SciPost Phys. Proc. 10, 037 (2022) · published 11 August 2022 | Toggle abstract · pdf

  Following the quark-hadron duality concept, we show that the number of hadrons generated in the deconfinement matter is entirely determined by the exact non-equilibrium Green's functions of partons in the medium and the vertex function governing the probability of the confinement-deconfinement phase transition. In such an approach, compactifying the standard (3+1) chromodynamics into $ QCD_{xy} + QCD_{zt}$, the rate of the hadrons produced in particle collisions is derived in the explicit form provided that the hadronization is the first order phase transition. The pion production is found to be in good agreement to the experimental results on the pion yield in pp collisions.

• Experimental status of LNU in B decays in LHCb

  Sean Benson on behalf of the LHCb collaboration

  SciPost Phys. Proc. 1, 011 (2019) · published 19 February 2019 | Toggle abstract · pdf

  In the Standard Model, the three charged leptons are identical copies of each other, apart from mass differences. Experimental tests of this feature in semileptonic decays of b-hadrons are highly sensitive to New Physics particles which preferentially couple to the 2nd and 3rd generations of leptons. A review of the latest lepton universality tests in semileptonic $b\to c$ transitions at LHCb is reported.

• Renormalization approach to the superconducting Kondo model

  Steffen Sykora, Tobias Meng

  SciPost Phys. 13, 016 (2022) · published 12 August 2022 | Toggle abstract · pdf

  An approach to bound states based on unitary transformations of Hamiltonians is presented. The method is applied to study the interaction between electrons in a BCS $s$-wave superconductor and a quantum spin. It is shown that known results from the t-matrix method and numerical studies are reproduced by this new method. As a main advantage, the method can straightforwardly be extended to study the topological properties of combined bound states in chains of many magnetic impurities. It also provides a uniform picture of the interplay between the Yu-Shiba-Rusinov (YSR) bound states and the Kondo singlet state.

• Multiple Andreev reflections in diffusive SINIS and SIFIS junctions

  Artem V. Polkin, Pavel A. Ioselevich

  SciPost Phys. 15, 100 (2023) · published 18 September 2023 | Toggle abstract · pdf

  We study Multiple Andreev Reflections in long diffusive superconductor(S)-normal metal(N)-superconductor junctions with low-transparency interfaces. Assuming strong thermalization in the weak link, we calculate the current-voltage dependence $I(V)$. At intermediate temperatures, $\varepsilon_\mathrm{Th}\ll T\ll\Delta$, the current is dominated by noncoherent multiple Andreev reflections and is obtained analytically. The results are generalized to a ferromagnetic junction. We find that the exchange field produces a non-trivial splitting of the subharmonic gap structure. This effect relies on thermalization and vanishes in SFS junctions with no energy relaxation in the weak link.

• Annihilating dark matter search with 12 years of Fermi LAT data in nearby galaxy clusters

  Charles Thorpe-Morgan, D. Malyshev, C.-A. Stegen, Andrea Santangelo, J. Jochum

  SciPost Phys. Proc. 12, 071 (2023) · published 10 July 2023 | Toggle abstract · pdf

  Galaxy clusters contain an abundance of dark matter making them attractive laboratories for indirect DM searches. This work details a search for signals of pair annihilation from WIMP dark matter in the GeV gamma ray regime. We perform this search in five low $z$ and high galactic latitude galaxy clusters (Centaurus, Coma, Virgo, Perseus and Fornax); using nearly 12 years of Fermi/LAT data. Through the non-detection of this characteristic signal, we derive constraints on the annihilation cross-section of DM pair annihilation into the $b\overline{b}$, $W^+W^-$ and $\gamma\gamma$ channels. The limits obtained are of a comparable magnitude to those of recently derived from Fermi/LAT observations of dwarf spheroidal galaxies.

• Charged lepton flavour violating processes

  Adrian Signer

  SciPost Phys. Proc. 1, 014 (2019) · published 19 February 2019 | Toggle abstract · pdf

  Charged lepton flavour violating processes are naturally present in many extensions of the Standard Model. After a brief overview on the experimental situation, an effective-field-theory framework is described that allows to interpret and compare the various experiments in a consistent way. The usefulness of this approach is then illustrated in the context of a specific model with a doubly charged scalar.