Publications

Order by: publication date number of citations

• Light thermal relics enabled by a second Higgs

  Johannes Herms, Sudip Jana, Vishnu P. K., Shaikh Saad

  SciPost Phys. Proc. 12, 046 (2023) · published 4 July 2023 | Toggle abstract · pdf

  Sub-GeV thermal relic dark matter typically requires the existence of a light mediator particle. We introduce the light two-Higgs-doublet portal, illustrated by a minimal UV-complete model for sub-GeV dark matter with kinematically forbidden annihilations into leptons. All new physics states in this scenario lie at or below the electroweak scale, affecting Higgs physics, the muon anomalous magnetic moment and potentially neutrino masses. Observation of radiative dark matter annihilation by future MeV gamma-ray telescopes would be key to unambiguously identify the scenario.

• Measurement of charged-particle production in single diffractive proton-proton collisions with the STAR detector

  Leszek Adamczyk

  SciPost Phys. Proc. 8, 081 (2022) · published 12 July 2022 | Toggle abstract · pdf

  We present results on the inclusive and identified (pion, kaon, proton and their antiparticles) charged-particle production in single diffractive (SD) dissociation process in proton-proton collisions at $\sqrt{s}=200$ GeV with the STAR detector at RHIC. The forward-scattered proton is measured in the Roman Pot (RP) system, while the charged particle tracks are reconstructed in the STAR Time Projection Chamber. The proton-antiproton production asymmetry is measured to study the baryon number transfer over a large rapidity interval in SD process. In addition, $K/\pi$ ratio is measured, showing a larger strangeness production at $p_T>0.5$ GeV/$\mathit{c}$ compared to measurements in inclusive proton-proton collisions.

• Towards DIS at N4LO

  Avanish Basdew-Sharma

  SciPost Phys. Proc. 8, 153 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We will report on an ongoing effort towards calculating the N4LO perturbative QCD corrections to the DIS total inclusive cross-section. We are developing a method based on differential equations and series expansion in the inverse Bjorken parameter. As a byproduct our calculation should also deliver analytic or at least precise numerical approximations for the four-loop splitting functions.

• Intermittency analysis of charged hadrons generated in Pb-Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV and 5.02 TeV

  Salman Khurshid Malik, Ramni Gupta

  SciPost Phys. Proc. 15, 012 (2024) · published 2 April 2024 | Toggle abstract · pdf

  Local density fluctuations are expected to scale as a universal power-law when the system approaches critical point. Such power-law fluctuations are studied within the framework of intermittency through the measurement of normalized factorial moments in ($\eta$, $\phi$) phase space. Observations and results from the intermittency analysis performed for charged particles in Pb-Pb collisions using PYTHIA8/Angantyr at 2.76 TeV and 5.02 TeV are reported. We observe no scaling behaviour in the particle generation for any of the centrality studied in narrow p$_T$ bins. The scaling exponent $\nu$ shows no dependence on the centrality ranges.

• Revisiting the flavor violating decays of the Tau and Mu leptons in the Standard Model with massive neutrinos

  Gerardo Hernández Tomé

  SciPost Phys. Proc. 1, 017 (2019) · published 19 February 2019 | Toggle abstract · pdf

  The flavor violating leptonic decays of the $\tau$ and $\mu$ leptons into three lighter charged leptons are revisited in the framework the Standard Model with massive neutrinos. In contrast to the previous prediction, we have found strongly suppressed rates for the $\tau^-\to \mu^- \ell^+ \ell^-$ ($\ell=\mu, e$) decays. Our results are in good agreement with the approximation of neglecting masses and momenta of the external particles in the loop integrals made in the first computation for the $\mu^- \to e^-e^+ e^-$ decay.

• Reweighting the quark Sivers function with STAR jet data

  Carlo Flore, Maria Elena Boglione, Umberto D'Alesio, Josè Osvaldo Gonzalez-Hernandez, Francesco Murgia, Alexei Prokudin

  SciPost Phys. Proc. 8, 034 (2022) · published 11 July 2022 | Toggle abstract · pdf

  The Bayesian reweighting procedure is applied for the first time to a TMD distribution, the quark Sivers function extracted from SIDIS data. By exploiting the recent published single spin asymmetry data for the inclusive jet production in $p^\uparrow p$ collisions from the STAR collaboration at RHIC, we show how such a procedure allows to incorporate the information contained in the new data set, without the need of re-fitting, and to explore a much wider $x$ region compared to SIDIS measurements. The reweighting method is also extended to the case of asymmetric errors, and the results show a significant improvement on the knowledge of the quark Sivers function.

• Interaction and collision of skyrmions in chiral antiferromagnets

  George Theodorou, Bruno Barton-Singer, Stavros Komineas

  SciPost Phys. 18, 037 (2025) · published 30 January 2025 | Toggle abstract · pdf

  Skyrmions in an antiferromagnet can travel as solitary waves in stark contrast to the situation in ferromagnets. Traveling skyrmion solutions have been found numerically in chiral antiferromagnets. We study head-on collision events between two skyrmions. We find that the result of the collision depends on the initial velocity of the skyrmions. For small velocities, the skyrmions shrink as they approach, then bounce back and eventually acquire almost their initial speed. For larger velocities, the skyrmions approach each other and shrink until they become singular points at some finite separation and are eventually annihilated. Considering skyrmion energetics, we can determine the regimes of the different dynamical behaviors. Using a collective co-ordinate approach, we reproduce the dynamics of the collisions including the variation of the size of the skyrmions and collapse above a critical velocity.

• Graviton mass and entanglement islands in low spacetime dimensions

  Hao Geng

  SciPost Phys. 19, 146 (2025) · published 4 December 2025 | Toggle abstract · pdf

  It has been conjectured and proven that entanglement island is not consistent with long-range (massless) gravity in a large class of spacetimes, including typical asymptotically anti-de Sitter spacetimes, in high spacetime dimensions. The conjecture and its proof are motivated by the observation that existing constructions of entanglement islands in high dimensions are all in gravitational theories where the graviton is massive for which the standard gravitational Gauss' law doesn't apply. In this letter, we show that this observation persists to lower dimensional cases. We achieve this goal by providing a unified description of the gravitational Gauss' law violation in island models that can work in any dimensions. This unified description teaches us new lessons on entanglement islands and subregion physics in quantum gravity. We focus on the case of the (1+1)-dimensional Jackiw-Teitelboim (JT) gravity for the purpose of demonstration.

• Loop equations for generalised eigenvalue models

  Edoardo Vescovi, Konstantin Zarembo

  SciPost Phys. 17, 017 (2024) · published 18 July 2024 | Toggle abstract · pdf

  We derive the loop equation for the 1-matrix model with generic difference-type measure for eigenvalues and develop a recursive algebraic framework for solving it to an arbitrary order in the coupling constant in and beyond the planar approximation. The planar limit is solved exactly for a one-parametric family of models and in the general case at strong coupling. The Wilson loop in the $\mathcal{N}=2^*$ super-Yang-Mills theory and the Hoppe model are used to illustrate our methods.

• Quasi-free limit in the deuteron-deuteron three-body break-up process

  R. Ramazani-Sharifabadi, H. R. Amir-Ahmadi, M. T. Bayat, I. Ciepał, M. Eslami-Kalantari, N. Kalantar-Nayestanaki, St. Kistryn, A. Kozela, M. Mahjour-Shafiei, H. Mardanpour, J. G. Messchendorp, M. Mohammadi-Dadkan, A. Ramazani-Moghaddam-Arani, E. Stephan, and H. Tavakoli-Zaniani

  SciPost Phys. Proc. 3, 057 (2020) · published 1 April 2020 | Toggle abstract · pdf

  Detailed measurements of vector and tensor analyzing powers of the 2H(d, dp)n breakup process are presented. The data were obtained using a polarized deuteron-beam with an energy of 65 MeV/nucleon impinging on a liquid-deuterium target. The experiment was conducted at the AGOR facility at KVI using the BINA 4Pi-detection system. The focus of this contribution is to analyze data of the dd scattering process in the regime at which the neutron acts as a spectator, which we refer to as the quasi-free (QF) limit. To achieve this, events for which the final-state deuteron and proton are coplanar have been analyzed and the data have been sorted for various reconstructed momenta of the missing neutron. In the limit of vanishing neutron momentum and at small deuteron-proton momentum transfer, the data match very well with measured and predicted spin observables of the elastic deuteron-proton scattering process. The agreement deteriorates rapidly with increasing neutron momentum and deuteron-proton momentum transfer. The results of coplanar configurations in four-body phase space are compared with the results of recent available theoretical calculations based on the Single-Scattering Approximation.