Publications

Order by: publication date number of citations

• Highlights of the results from the GRAPES-3 experiment

  Hariharan Balakrishnan, S. Ahmad, M. Chakraborty, S.R. Dugad, U.D. Goswami, S.K. Gupta, Y. Hayashi, P. Jagadeesan, A. Jain, P. Jain, S. Kawakami, H. Kojima, S. Mahapatra, P.K. Mohanty, R. Moharana, Y. Muraki, P.K. Nayak, T. Nonaka, A. Oshima, D. Pattanaik, B.P. Pant, M. Rameez, K. Ramesh, L.V. Reddy, S. Shibata, F. Varsi, M. Zuberi

  SciPost Phys. Proc. 13, 021 (2023) · published 28 September 2023 | Toggle abstract · pdf

  The GRAPES-3 experiment is a unique, extensive air shower experiment consisting of 400 scintillator detectors spread over 25000 m$^2$ and a 560 m$^2$ muon telescope. The experiment located at Ooty, India, has been collecting data for the past two decades. The unique capabilities of GRAPES-3 have allowed the study of cosmic rays over energies from a few TeV to tens of PeV and beyond. The measurement of the directional flux of muons (E$_\mu$≥1 GeV) by the large muon telescope permits an excellent gamma-hadron separation, which then becomes a powerful tool in the study of multi-TeV gamma-ray sources and the composition of primary cosmic rays. However, the high precision measurements also enable studies of transient atmospheric and interplanetary phenomena such as those produced by thunderstorms and geomagnetic storms. This paper presents some exciting new and recent results, including updates on various ongoing analyses.

• Anisotropic ionization threshold and directional sensitivity in solid state DM detectors

  Matti Heikinheimo, Sebastian Sassi, Kimmo Tuominen, Kai Nordlund, Nader Mirabolfathi

  SciPost Phys. Proc. 12, 020 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The threshold displacement energy for nuclear recoils depends strongly on the direction of the recoiling nucleus with respect to the crystal lattice. Assuming that similar dependence holds for the ionization threshold for low energy nuclear recoils, we explore the consequences of the resulting directional dependence of the observable event rate in ionization detectors. For low mass dark matter, this effect leads to a daily modulation in the event rate. We discuss how this effect can be utilized to separate the DM signal from the solar neutrino background and how the structure of the modulation signal can be used to identify the type of the DM-nucleon coupling.

• The prediction of anyons: Its history and wider implications

  Gerald A. Goldin

  SciPost Phys. Proc. 14, 005 (2023) · published 23 November 2023 | Toggle abstract · pdf

  Prediction of "anyons," often attributed exclusively to Wilczek, came first from Leinaas and Myrheim in 1977, and independently from Goldin, Menikoff, and Sharp in 1980-81. In 2020, experimentalists successfully created anyonic excitations. This paper discusses why the possibility of quantum particles in two-dimensional space with intermediate exchange statistics eluded physicists for so long after bosons and fermions were understood. The history suggests ideas for the preparation of future researchers. I conclude by addressing failures to attribute scientific achievements accurately, both inadvertent and intentional. Such practices disproportionately hurt women and minorities in physics.

• Anisotropic Zeeman Splitting in YbNi4P2

  Sara Karbassi, Saman Ghannadzadeh, Kristin Kliemt, Manuel Brando, Cornelius Krellner, Sven Friedemann

  SciPost Phys. 5, 056 (2018) · published 30 November 2018 | Toggle abstract · pdf

  The electronic structure of heavy-fermion materials is highly renormalised at low temperatures with localised moments contributing to the electronic excitation spectrum via the Kondo effect. Thus, heavy-fermion materials are very susceptible to Lifshitz transitions due to the small effective Fermi energy arising on parts of the renormalised Fermi surface. Here, we study Lifshitz transitions that have been discovered in YbNi4P2 in high magnetic fields. We measure the angular dependence of the critical fields necessary to induce a number of Lifshitz transitions and find it to follow a simple Zeeman-shift model with anisotropic g-factor. This highlights the coherent nature of the heavy quasiparticles forming a renormalised Fermi surface. We extract information on the orientation of the Fermi surface parts giving rise to the Lifshitz transitions and we determine the anisotropy of the effective g-factor to be $\eta \approx 3.8$ in good agreement with the crystal field scheme of YbNi4P2.

• Emergent symmetries in atomic nuclei: Probing nuclear dynamics and physics beyond the standard model

  Kristina D. Launey, K. S. Becker, G. H. Sargsyan, O. M. Molchanov, M. Burrows, A. Mercenne, T. Dytrych, D. Langr, J. P. Draayer

  SciPost Phys. Proc. 14, 007 (2023) · published 23 November 2023 | Toggle abstract · pdf

  Dominant shapes naturally emerge in atomic nuclei from first principles, thereby establishing the shape-preserving symplectic Sp(3, $\mathbb{R}$) symmetry as remarkably ubiquitous and almost perfect symmetry in nuclei. We discuss the critical role of this emergent symmetry in enabling machine-learning descriptions of heavy nuclei, ab initio modeling of $\alpha$ clustering and collectivity, as well as tests of beyond-the-standard-model physics. In addition, the Sp(3, $\mathbb{R}$) and SU(3) symmetries provide relevant degrees of freedom that underpin the ab initio symmetry-adapted no-core shell model with the remarkable capability of reaching nuclei and reaction fragments beyond the lightest and close-to-spherical species.

• On irregularities in the cosmic ray spectrum of \(10^{16}-10^{18}\) eV range

  Stanislav P. Knurenko, Igor S. Petrov

  SciPost Phys. Proc. 13, 020 (2023) · published 28 September 2023 | Toggle abstract · pdf

  Existing small, medium and large arrays for the study of cosmic rays of ultra-high energies are aimed for obtaining information about our galaxy and extragalactic space, namely to search and study astronomical objects that produce the flux of relativistic particles. The drift and interaction of such particles with magnetic fields and shock waves taking place in interstellar space causes the same interest. The shape of the energy spectrum of cosmic rays in the energy range $10^{15}-10^{18}$ eV, where the "knee" and the "second knee" are observed, can be formed as a superposition of the partial spectra of various chemical elements. Verification of galactic models, using recent experimental spectral data, makes it possible to study the nature of the galactic and extragalactic components of cosmic rays. The paper presents the result of the energy spectrum of cosmic rays in the range $10^{16}-10^{18}$ eV of measurements obtained with the Small Cherenkov array - a part of the Yakutsk array.

• The full coverage approach to the detection of Extensive Air Showers

  Giuseppe Di Sciascio

  SciPost Phys. Proc. 13, 019 (2023) · published 28 September 2023 | Toggle abstract · pdf

  A shower array exploiting the full coverage approach with a high segmentation of the readout allow to image the front of atmospheric showers with unprecedented resolution and detail. The grid distance determines the energy threshold (small energy showers are lost in the gap between detectors) and the quality of the shower sampling. Therefore, this experimental solution is needed to detect showers with a threshold in the 100 GeV range. The full coverage approach has been exploited in the ARGO-YBJ experiment. In this contribution we will summarise the advantages of this technique and discuss possible applications in new wide field of view detectors.

• Uncertainty in mean $X_{\rm max}$ from diffractive dissociation estimated using measurements of accelerator experiments

  Ken Ohashi, Hiroaki Menjo, Takashi Sako, Yoshitaka Itow

  SciPost Phys. Proc. 13, 018 (2023) · published 28 September 2023 | Toggle abstract · pdf

  Mass composition is important for understanding the origin of ultra-high-energy cosmic rays. However, interpretation of mass composition from air shower experiments is challenging, owing to significant uncertainty in hadronic interaction models adopted in air shower simulation. A particular source of uncertainty is diffractive dissociation, as its measurements in accelerator experiments demonstrated significant systematic uncertainty. In this research, we estimate the uncertainty in $\langle X_{\rm max}\rangle$ from the uncertainty of the measurement of diffractive dissociation by the ALICE experiment. The maximum uncertainty size of the entire air shower was estimated to be $^{+4.0}_{-5.6} \mathrm{g/cm^2}$ for air showers induced by $10^{17}$ eV proton, which is not negligible in the uncertainty of $\langle X_{\rm max}\rangle$ predictions.

• The droplet formation-dissolution transition in different ensembles: Finite-size scaling from two perspectives

  Franz Paul Spitzner, Johannes Zierenberg, Wolfhard Janke

  SciPost Phys. 5, 062 (2018) · published 13 December 2018 | Toggle abstract · pdf

  The formation and dissolution of a droplet is an important mechanism related to various nucleation phenomena. Here, we address the droplet formation-dissolution transition in a two-dimensional Lennard-Jones gas to demonstrate a consistent finite-size scaling approach from two perspectives using orthogonal control parameters. For the canonical ensemble, this means that we fix the temperature while varying the density and vice versa. Using specialised parallel multicanonical methods for both cases, we confirm analytical predictions at fixed temperature (rigorously only proven for lattice systems) and corresponding scaling predictions from expansions at fixed density. Importantly, our methodological approach provides us with reference quantities from the grand canonical ensemble that enter the analytical predictions. Our orthogonal finite-size scaling setup can be exploited for theoretical and experimental investigations of general nucleation phenomena - if one identifies the corresponding reference ensemble and adapts the theory accordingly. In this case, our numerical approach can be readily translated to the corresponding ensembles and thereby proves very useful for numerical studies of equilibrium droplet formation, in general.

• Remembering David J. Rowe

  John L. Wood, Piet Van Isacker

  SciPost Phys. Proc. 14, 013 (2023) · published 23 November 2023 | Toggle abstract · pdf

  David Rowe was a highly respected theoretical physicist who made seminal contributions that improved our understanding of the atomic nucleus, in particular of the collective behaviour of its constituent nucleons - results he often obtained with the use of sophisticated group-theoretical methods. He will also be remembered as the (co-)author of monographs on nuclear physics, written with the scientific rigour that was characteristic of his research.