Publications

Order by: publication date number of citations

• Towards the computation of inclusive decay rates using lattice QCD

  Paolo Gambino, Shoji Hashimoto, Sandro Mächler, Marco Panero, Francesco Sanfilippo, Silvano Simula, Antonio Smecca, Nazario Tantalo

  SciPost Phys. Proc. 15, 004 (2024) · published 2 April 2024 | Toggle abstract · pdf

  We present a non-perturbative computation of inclusive rates of semileptonic decays of heavy mesons from lattice QCD simulations. The calculation is based on the extraction of smeared spectral functions obtained from four-point Euclidean correlation functions computed on configuration ensembles of the JLQCD and ETM collaborations. We compare our results for the inclusive decay rates with analytical predictions from the operator-product expansion, finding a good agreement for the calculation of the inclusive decay rate. This opens the path to the theoretical determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $V_{cb}$ to a level of precision competitive with the present experimental uncertainty.

• Recent results from LHCb for astroparticle physics

  Hans Dembinski on behalf of the LHCb collaboration

  SciPost Phys. Proc. 13, 016 (2023) · published 28 September 2023 | Toggle abstract · pdf

  The LHCb experiment is a general-purpose forward spectrometer designed for the study of heavy flavour physics at the LHC. The acceptance in the pseudorapidity range $2 < \eta < 5$ with full tracking and particle identification capabilities down to very small transverse momentum make LHCb also ideal to study hadron production in the forward region. Measuring and modelling these processes is essential for the simulation of interactions of high-energy cosmic rays with matter, like Earth's atmosphere or the interstellar medium. We present recently published analyses from the LHCb collaboration relevant for this application.

• The composition of cosmic rays according to the data on EAS cores

  S. B. Shaulov, V. A. Ryabov, S. E. Pyatovsky, A. L. Shepetov, V. V. Zhukov

  SciPost Phys. Proc. 13, 014 (2023) · published 28 September 2023 | Toggle abstract · pdf

  The main purpose of this work is to find the causes of the break of the cosmic ray spectrum at an energy of 3 PeV, which is called the knee. The solution of the problem is associated with the determination of the nuclear composition of cosmic rays in the knee area. The conclusions of this work are based on the analysis of the characteristics of the EAS cores obtained using X-ray emulsion chambers. According to these data, a number of anomalous effects are observed in the knee region, such as scaling violation in the spectra of secondary hadrons, an excess of muons in EAS with gamma families and others. At the same energies equivalent to 1-100 PeV the laboratory system colliders show scaling behavior. So analysis of the data on the EAS cores suggests that the knee in their spectrum is formed by a component of cosmic rays of a non-nuclear nature, possibly consisting of stable (quasi-stable) particles of hypothetical strange quark matter, which named strangelets. This is the only model of the knee compatible with the magnetic rigidity of the nuclear spectra break R=100 TV. In fact, stranglets are stable heavy quasi-nuclei with a positive electric charge of Z=30-1000, so the mechanism of their acceleration coincides with the nuclear one. The break of the cosmic ray spectrum can be associated with a significantly larger mass of strangelets compared to nuclei.

• Application of Lorentzian CFT Principal Series Representation to Near Forward Scattering

  Pulkit Agarwal, Richard C. Brower, Timothy G. Raben, Chung-I Tan

  SciPost Phys. Proc. 10, 026 (2022) · published 11 August 2022 | Toggle abstract · pdf

  We present a discussion on recent progress in high energy diffraction from the perspective of AdS/CFT, through which a unified treatment for both perturbative and nonperturbative Pomeron emerges. By working with Unitary Irreducible Representation of Conformal group, a frame is provided in extending AdS/CFT to both forward and nearforward scattering. We present an analysis involving an exact solution to conformal blocks in Minkowski CFT and discuss possible applications. Phenomenological applications can range from forward scattering to DIS/DVCS/TMD at LHC energies and beyond.

• What charged cosmic rays tell us on dark matter

  Pierre Salati

  SciPost Phys. Proc. 12, 067 (2023) · published 5 July 2023 | Toggle abstract · pdf

  Dark matter particles could be the major component of the haloes of galaxies. Their mutual annihilations or decays would produce an indirect signature under the form of high-energy cosmic-rays. The focus of this presentation is on antimatter species, a component so rare that any excess over the background should be easily detected. After a recap on Galactic propagation, I will discuss positrons, antiprotons and anti-nuclei. For each of these species, anomalies have been reported. The antiproton excess, for instance, is currently a hot topic. Alas, it does not resist a correct treatment of theoretical and data errors.

• The Mu3e experiment at PSI

  Alessandro Bravar on behalf of the Mu3e Collaboration

  SciPost Phys. Proc. 1, 037 (2019) · published 21 February 2019 | Toggle abstract · pdf

  Mu3e will search for charged Lepton Flavor Violation in the neutrinoless muon decay $\mu^+ \rightarrow e^+ e^- e^+$ with a sensitivity down to $10^{-16}$ (90\% C.L.) using the world most intense continuous muon beam at PSI. This search requires a large acceptance detector capable of coping with rates of up to $2 \times 10^9$ stopped muons per second with excellent momentum, spatial, and time resolution. The Mu3e detector is based on thin monolithic active silicon pixel sensors for tracking in conjunction with scintillating fibers and tiles for timing measurements. The Mu3e apparatus is under constructions and first data is expected in 2020.

• Point sources of ultra-high-energy neutrinos: Minimalist predictions for near-future discovery

  Damiano F. G. Fiorillo, Mauricio Bustamante, Victor B. Valera

  SciPost Phys. Proc. 13, 009 (2023) · published 28 September 2023 | Toggle abstract · pdf

  The discovery of ultra-high-energy neutrinos, with energies above 100 PeV, may soon be within reach of upcoming neutrino telescopes. We present a robust framework to compute the statistical significance of point-source discovery via the detection of neutrino multiplets. We apply it to the radio array component of IceCube-Gen2. To identify a source with $3\sigma$ significance, IceCube-Gen2 will need to detect a triplet, at best, and an octuplet, at worst, depending on whether the source is steady-state or transient, and on its position in the sky. The discovery, or absence, of sources significantly constrains the properties of the source population.

• Recent jet and jet substructure measurements at the LHC, and ML based tagging

  Meena Meena

  SciPost Phys. Proc. 10, 022 (2022) · published 10 August 2022 | Toggle abstract · pdf

  Recent jet and jet substructure measurements at the LHC, and of machine-learning-based tagging techniques are presented using proton-proton collision data collected by the ATLAS and CMS experiments at CERN's Large Hadron Collider. These measurements are crucial for precise tests of electroweak and pQCD calculations and searches for physics beyond the Standard Model. The measurements are compared with several Monte Carlo event generator predictions which provide valuable input to the tuning of perturbative and non-perturbative models and to constraining model parameters of advanced parton-shower Monte Carlo programs.

• Pressure-dependent structural and electronic instabilities in LaSb$_2$

  Theodore I. Weinberger, Christian K. de Podesta, Jiasheng Chen, Stephen A. Hodgson, F. Malte Grosche

  SciPost Phys. Proc. 11, 018 (2023) · published 6 June 2023 | Toggle abstract · pdf

  LaSb$_2$ exhibits a large, non-saturating, linear magnetoresistance at low temperatures, defying the expectations of Fermi liquid theory. This is thought to be caused by charge density wave order emerging below an abrupt, hysteretic anomaly in the resistivity at $\sim$ 355 K. We find that, under hydrostatic pressure, this anomaly becomes much more pronounced, develops strong hysteresis, and shifts rapidly towards lower temperatures. The anomaly is fully suppressed by only 6 kbar. Moreover, we observe a second transition anomaly at lower temperature, which likewise disappears under pressure. These findings are discussed in the context of a structural transition recently discovered in the sister material CeSb$_2$ and of density functional theory calculations, which indicate that the SmSb$_2$-type structure adopted by LaSb$_2$ at ambient conditions is unstable at moderate applied pressures.

• Sustaining a temperature difference

  Matteo Polettini, Alberto Garilli

  SciPost Phys. 9, 030 (2020) · published 2 September 2020 | Toggle abstract · pdf

  We derive an expression for the minimal rate of entropy that sustains two reservoirs at different temperatures $T_0$ and $T_\ell$. The law displays an intuitive $\ell^{-1}$ dependency on the relative distance and a characterisic $\log^2 (T_\ell/T_0)$ dependency on the boundary temperatures. First we give a back-of-envelope argument based on the Fourier Law (FL) of conduction, showing that the least-dissipation profile is exponential. Then we revisit a model of a chain of oscillators, each coupled to a heat reservoir. In the limit of large damping we reobtain the exponential and squared-log behaviors, providing a self-consistent derivation of the FL. For small damping "equipartition frustration" leads to a well-known balistic behaviour, whose incompatibility with the FL posed a long-time challenge.