Publications

Order by: publication date number of citations

• Complementarity of Lepton-Charge and Forward-Backward Drell-Yan Asymmetries for Precision Electroweak Measurements and Quark Density Determinations

  J. Fiaschi, F. Giuli, F. Hautmann, S. Moretti

  SciPost Phys. Proc. 8, 038 (2022) · published 12 July 2022 | Toggle abstract · pdf

  We address the impact of future measurements of charged and neutral current Drell-Yan (DY) asymmetries and their combination on Parton Distribution Functions (PDFs) uncertainties. We quantify the reduction of PDF uncertainties using the QCD tool xFitter. We examine the effects of such reduced PDF errors on both Standard Model (SM) and Beyond SM (BSM) observables.

• A novel formulation of the unintegrated gluon distribution for DIS

  Yacine Mehtar-Tani

  SciPost Phys. Proc. 8, 037 (2022) · published 12 July 2022 | Toggle abstract · pdf

  In this talk, we revisit inclusive DIS in the small $x$ limit and derive a new factorization formula that accounts for leading powers in both Bjorken and Regge limits. In this semi-classical description, we obtain a new unintegrated gluon distribution which encompasses both the dipole operator and the gluon Parton Distribution Function with an explicit dependence on the longitudinal momentum fraction $x$.

• The open XYZ spin 1/2 chain: Separation of variables and scalar products for boundary fields related by a constraint

  Giuliano Niccoli, Veronique Terras

  SciPost Phys. 19, 090 (2025) · published 8 October 2025 | Toggle abstract · pdf

  We consider the open XYZ spin chain with boundary fields. We solve the model by the new Separation of Variables approach introduced in [J. M. Maillet and G. Niccoli, J. Stat. Mech.: Theory Exp. 094020 (2019)]. In this framework, the transfer matrix eigenstates are obtained as a particular sub-class of the class of so-called separate states. We consider the problem of computing scalar products of such separate states. As usual, they can be represented as determinants with rows labelled by the inhomogeneity parameters of the model. We notably focus on the special case in which the boundary parameters parametrising the two boundary fields satisfy one constraint, hence enabling for the description of part of the transfer matrix spectrum and eigenstates in terms of some elliptic polynomial $Q$-solution of a usual $TQ$-equation. In this case, we show how to transform the aforementioned determinant for the scalar product into some more convenient form for the consideration of the homogeneous and thermodynamic limits: as in the open XXX or XXZ cases, our result can be expressed as some generalisation of the so-called Slavnov determinant.

• Boundary layers, transport and universal distribution in boundary driven active systems

  Pritha Dolai, Arghya Das

  SciPost Phys. 19, 088 (2025) · published 8 October 2025 | Toggle abstract · pdf

  We discuss analytical results for a run-and-tumble particle (RTP) in one dimension in presence of boundary reservoirs. It exhibits "kinetic boundary layers", nonmonotonous distribution, current without density gradient, diffusion facilitated current reversal and optimisation on tuning dynamical parameters, and a new transport effect in the steady state. The spatial and internal degrees of freedom together possess a symmetry, using which we find the eigenspectrum for large systems. The eigenvalues are arranged in two bands which can mix in certain conditions resulting in a crossover in the relaxation. The late time distribution for large systems is obtained analytically; it retains a strong and often dominant "active" contribution in the bulk rendering an effective passive-like description inadequate. A nontrivial "Milne length" also emerges in the dynamics. Finally, a novel universality is proposed in the absorbing boundary problem for dynamics with short-range colored noise. Active processes driven by active reservoirs may thus provide a common physical ground for diverse and new nonequilibrium phenomena.

• Leptophilic portals to new physics at colliders

  P. S. Bhupal Dev

  SciPost Phys. Proc. 17, 007 (2025) · published 23 July 2025 | Toggle abstract · pdf

  Observed neutrino oscillations imply that the global lepton flavor symmetry of the Standard Model must be broken. Therefore, searches for lepton flavor violation (LFV) are promising probes of new physics beyond the Standard Model. High-energy colliders provide a powerful tool to study LFV effects, which are complementary to the low-energy charged LFV searches. Here we discuss the possibility of LFV signals at colliders arising from exotic Higgs decays, and from leptophilic scalar and vector portal scenarios.

• Searches for lepton flavor violation in meson decays at Belle

  Sourav Patra

  SciPost Phys. Proc. 17, 009 (2025) · published 23 July 2025 | Toggle abstract · pdf

  We report the results of recent searches on charged lepton flavor violation using the $e^+e^-$ collision data collected by the Belle detector. In the first section, we present a search for the lepton-flavor-violating decays $B{}^0_s → \ell^{\mp}\tau^{±}$, where $\ell = e, \mu$, using $121\ \mathrm{fb}^{-1}$ data collected at the $\Upsilon(5S)$ resonance. We also search for the lepton-flavour-violating decays $B^+ \to K^+ \tau^± \ell^\mp$, with $\ell = (e, \mu)$, using $711\ \mathrm{fb}^{-1}$ $\Upsilon(4S)$ data sample. Finally, we present a search for the charged lepton-flavor-violating decays $\Upsilon(1S)→\ell^±\ell^{\prime\mp}$ and radiative charged lepton-flavour-violating decays $\Upsilon(1S)→\gamma\ell^±\ell^{\prime\mp}$ [$\ell,\ell^\prime = e, \mu, \tau$] using $25\ \mathrm{fb}^{-1}$ data recorded at $\Upsilon(2S)$ resonance. This search uses $\Upsilon(1S)$ mesons produced in $\Upsilon(2S)→\pi^+\pi^-\Upsilon(1S)$ transitions.

• Chiral Belle: e-Beam polarization upgrade of SuperKEKB

  J. Michael Roney

  SciPost Phys. Proc. 17, 012 (2025) · published 23 July 2025 | Toggle abstract · pdf

  Recent R&D work associated with upgrading the SuperKEKB $e^+e^-$ collider with polarized electron beams is presented. The Chiral Belle physics program enables a set of unique precision measurements using the Belle II detector. It includes a set of measurements of $\sin^2\theta_W$ via separate left-right asymmetry ($A_{LR}$) measurements in annihilations to pairs of electrons, muons, taus, charm and b-quarks that yield precisions matching or exceeding those of the current world averages from measurements at the $Z^0$-pole, but at 10GeV, thereby also probing the running of the couplings. Chiral Belle will also probe for new physics via the highest precision measurements of neutral current universality ratios and precision measurements of tau lepton properties, including the tau magnetic moment. After summarizing the physics goals, developments related to provision of the polarized source, the new components of the accelerator lattice that rotate the electron spin from transverse to longitudinal at the interaction point, and polarimetry of the electron beam will be reported.

• Long-time divergences in the nonlinear response of gapped one-dimensional many-particle systems

  Michele Fava, Sarang Gopalakrishnan, Romain Vasseur, Siddharth A. Parameswaran, Fabian H. L. Essler

  SciPost Phys. 19, 086 (2025) · published 6 October 2025 | Toggle abstract · pdf

  We consider one dimensional many-particle systems that exhibit kinematically protected single-particle excitations over their ground states. We show that momentum and time-resolved 4-point functions of operators that create such excitations diverge linearly in particular time differences. This behaviour can be understood by means of a simple semiclassical analysis based on the kinematics and scattering of wave packets of quasiparticles. We verify that our wave packet analysis correctly predicts the long-time limit of the four-point function in the transverse field Ising model through a form factor expansion. We present evidence in favour of the same behaviour in integrable quantum field theories. In addition, we extend our discussion to experimental protocols where two times of the four-point function coincide, e.g. 2D coherent spectroscopy and pump-probe experiments. Finally, focusing on the Ising model, we discuss subleading corrections that grow as the square root of time differences. We show that the subleading corrections can be correctly accounted for by the same semiclassical analysis, but also taking into account wave packet spreading.

• Anomalous coupling studies with forward protons at the LHC

  C. Royon

  SciPost Phys. Proc. 8, 115 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We describe the gain on sensitivities to quartic $\gamma \gamma \gamma \gamma$, $\gamma \gamma WW$ and $\gamma \gamma \gamma Z$ anomalous couplings and to the search for Axion-Like Particles by two or three orders of magnitude with respect to standard methods at the LHC by tagging intact protons in the final state.

• A sharp transition in quantum chaos and thermodynamics of mass deformed SYK model

  Tomoki Nosaka

  SciPost Phys. Proc. 4, 006 (2021) · published 13 August 2021 | Toggle abstract · pdf

  We review our recent work [arXiv:2009.10759] where we studied the chaotic property of the two coupled Sachdev-Ye-Kitaev systems exhibiting a Hawking-Page like phase transition. By computing the out-of-time-ordered correlator in the large N limit by using the bilocal field formalism, we found that the chaos exponent of this model shows a discontinuous fall-off at the phase transition temperature. Hence in this model the Hawking-Page like transition is correlated with a transition in chaoticity, as expected from the relation between a black hole geometry and the chaotic behavior in the dual field theory.