Publications

Order by: publication date number of citations

Directional dark matter searches

Elisabetta Baracchini

SciPost Phys. Proc. 12, 002 (2023) · published 3 July 2023 | · pdf

The importance of directly detect and experimentally probe the nature of Dark Matter (DM) is universally and incontrovertibly recognised as one of the most compelling tasks of today's fundamental physics. Directional DM searches aim at developing experimental techniques that can give access to the measurement of the incoming direction of the DM particle. This can provide a correlation with an astrophysical source that no background whatsoever can mimic and offers an unique key for a positive, unambiguous identification of a DM signal.
Probing hadronic interactions with measurements from the Pierre Auger Observatory

B. Andrada

SciPost Phys. Proc. 10, 005 (2022) · published 10 August 2022 | · pdf

The Pierre Auger Observatory is the largest facility in the world to study ultra-high-energy cosmic rays. It has a hybrid detection technique that combines the observation of the longitudinal development of extensive air showers and the measurement of their particles at the ground. This capability has opened the possibility to probe hadronic interactions taking place at energies well beyond those accessible by human-made accelerators. In this report, we present a selection of the latest results on hadronic interactions with measurements from the Pierre Auger Observatory. These data span over three decades in energy, showing the tension between data from the muon component of air showers and predictions based on the most updated hadronic interaction models.
Measurement of splittings along a jet shower in $\sqrt{s} = 200$ GeV pp collisions at STAR

Raghav Kunnawalkam Elayavalli

SciPost Phys. Proc. 8, 059 (2022) · published 12 July 2022 | · pdf

Jets are algorithmic proxies of hard scattered partons, i.e. quarks and gluons, in high energy particle collisions. The STAR collaboration presents the first measurements of substructure observables at the first, second and third splits in the jet clustering tree via the iterative SoftDrop procedure. For each of these splits, we measure the fully corrected groomed shared momentum fraction (\zg) and groomed jet radius (\rg). We discuss the evolution of jet substructure in both the angular and momentum scales which allows for a self-similarity test of the DGLAP splitting function. We compare the fully corrected data to Monte Carlo models, providing stringent constraints on model parameters related to the parton shower and non-perturbative effects such as hadronization.
Indirect searches for dark matter with the nEDM spectrometer

S. Roccia, G. Zsigmond on behalf of the nEDM collaboration at PSI

SciPost Phys. Proc. 5, 028 (2021) · published 6 September 2021 | · pdf

The nEDM apparatus at PSI has been used to search for different dark matter signatures utilizing its high sensitivity to shifts in the neutron precession frequency and its well-controlled low magnetic field at the microT level. Such a shift could be interpreted as a consequence of a short-range spin-dependent interaction that could possibly be mediated by axions or axion-like particles, or as an axion-induced oscillating electric dipole moment of the neutron. Another search, based on so-called UCN disappearance measurements, targeted previously reported signals of neutron to mirror-neutron oscillations. These dark matter searches confirmed and improved previous results, as detailed in this review.
Introduction to Hamiltonian formulation of general relativity and homogeneous cosmologies

Rishabh Jha

SciPost Phys. Lect. Notes 73 (2023) · published 11 August 2023 | · pdf

We give a pedagogical introduction to the Hamiltonian formalism of general relativity at an advanced undergraduate and graduate levels. After covering the mathematical pre-requisites as well as the 3+1-decomposition of spacetime, we proceed to discuss the Arnowitt-Deser-Misner (ADM) formalism (a Hamiltonian approach) of general relativity. Then we proceed to give a brief but self-contained introduction to homogeneous (but not necessarily isotropic) universes and discuss the associated Bianchi classification. We first study their dynamics in the Lagrangian formulation, followed by the Hamiltonian formulation to show the equivalence of both approaches. We present a variety of examples to illustrate the ADM formalism: (i) free & massless scalar field coupled to homogeneous (in particular, Bianchi IX) universe, (ii) scalar field with a potential term coupled to Bianchi IX universe, (iii) electromagnetic field coupled to gravity in general, and (iv) electromagnetic field coupled to Bianchi IX universe.
Linear stability of Einstein and de Sitter universes in the quadratic theory of modified gravity

Mudhahir Al-Ajmi

SciPost Phys. Proc. 4, 012 (2021) · published 13 August 2021 | · pdf

We consider the Einstein static and the de Sitter universe solutions and examine their instabilities in a subclass of quadratic modified theories for gravity. This modification proposed by Nash is an attempt to generalize general relativity. Interestingly, we discover that the Einstein static universe is unstable in the context of the modified gravity. In contrast to Einstein static universe, the de Sitter universe remains stable under metric perturbation up to the second order.
Position-dependent mass quantum systems and ADM formalism

Davood Momeni

SciPost Phys. Proc. 4, 009 (2021) · published 13 August 2021 | · pdf

The classical Einstein-Hilbert (EH) action for general relativity (GR) is shown to be formally analogous to the classical system with position-dependent mass (PDM) models. The analogy is developed and used to build the covariant classical Hamiltonian as well as defining an alternative phase portrait for GR. The set of associated Hamilton's equations in the phase space is presented as a first-order system dual to the Einstein field equations. Following the principles of quantum mechanics, I build a canonical theory for the classical general. A fully consistent quantum Hamiltonian for GR is constructed based on adopting a high dimensional phase space. It is observed that the functional wave equation is timeless. As a direct application, I present an alternative wave equation for quantum cosmology. In comparison to the standard Arnowitt-Deser-Misner(ADM) decomposition and quantum gravity proposals, I extended my analysis beyond the covariant regime when the metric is decomposed into the 3+1 dimensional ADM decomposition. I showed that an equal dimensional phase space can be obtained if one applies ADM decomposed metric.
Near-extremal limits of warped black holes

Ankit Aggarwal, Alejandra Castro, Stéphane Detournay, Beatrix Mühlmann

SciPost Phys. 15, 083 (2023) · published 7 September 2023 | · pdf

A holographic description of three-dimensional warped black holes suffers from ambiguities due to a seemingly harmless choice of coordinate system. This gives rise to the notion of ensembles in warped black holes, and we focus on two of them: the canonical and quadratic ensemble. Our aim is to quantify the imprint of these ensembles in the near-extremal limit of a warped black hole. To this end, for each ensemble, we explore the thermodynamic response and evaluate greybody factors. We also set-up a holographic dictionary in their near-AdS$_2$ region, and decode aspects of the dual near-CFT$_1$. This gives us different perspectives of the black hole that we can contrast and compare. On the one hand, we find perfect agreement between the near-extremal limit of the canonical ensemble warped black holes, their near-AdS$_2$ effective analysis, and a warped conformal field theory description. On the other, we are led to rule out the quadratic ensemble due to inconsistencies at the quantum level with the near-AdS$_2$ effective description.
Cosmic ray measurements with IceCube and IceTop

Dennis Soldin (for the IceCube Collaboration)

SciPost Phys. Proc. 13, 002 (2023) · published 28 September 2023 | · pdf

IceCube is a cubic-kilometer Cherenkov detector in the deep ice at the geographic South Pole. The dominant event yield in the deep ice detector consists of penetrating atmospheric muons with energies above approximately 300 GeV, produced in cosmic ray air showers. In addition, the surface array, IceTop, measures the electromagnetic component and GeV muons of air showers. Hence, IceCube and IceTop yield unique opportunities to study cosmic rays with unprecedented statistics in great detail. We will present recent results of comic ray measurements from IceCube and IceTop. In this overview, we will highlight measurements of the energy spectrum of cosmic rays from 250 TeV up to the EeV range and their mass composition above 3 PeV. We will also report recent results from measurements of the muon content in air showers and discuss their consistency with predictions from current hadronic interaction models.
Muon puzzle in inclined muon bundles detected by NEVOD-DECOR

A. G. Bogdanov, N. S. Barbashina, S. S. Khokhlov, V. V. Kindin, R. P. Kokoulin, K. G. Kompaniets, A. Y. Konovalova, G. Mannocchi, A. A. Petrukhin, V. V. Shutenko, G. Trinchero, V. S. Vorobev, I. I. Yashin, E. A. Yurina, E. A. Zadeba

SciPost Phys. Proc. 13, 003 (2023) · published 28 September 2023 | · pdf

The data of cosmic ray NEVOD-DECOR experiment on the investigation of inclined muon bundles for a long time period (May 2012 - March 2021) are presented. The analysis showed that the observed intensity of muon bundles at primary cosmic ray energies of about 1 EeV and higher can be compatible with the expectation in frame of widely used hadron interaction models only under the assumption of an extremely heavy mass composition. This conclusion is consistent with data of several experiments on investigations of muon content in air showers, but contradicts the available fluorescence data on $X_{\text{max}}$ which favor a light mass composition at these energies. In order to clarify the nature of the "muon puzzle", investigations of the muon bundle energy deposit in the detector material were carried out. For the first time, experimental estimates of the average energy of muons in the bundles of inclined air showers initiated by primary particles with energies from 10 to 1000 PeV have been obtained.

Previous 1 ... 9 10 11 12 13 14 15 16 17 18 19 Next