Publications

Order by: publication date number of citations

• Self-binding of one-dimensional fermionic mixtures with zero-range interspecies attraction

  Jules Givois, Andrea Tononi, and Dmitry S. Petrov

  SciPost Phys. 14, 091 (2023) · published 3 May 2023 | Toggle abstract · pdf

  For sufficiently large mass ratios the attractive exchange force caused by a single light atom interacting with a few heavy identical fermions can overcome their Fermi degeneracy pressure and bind them into an $N+1$ cluster. Here, by using a mean-field approach valid for large $N$, we find that $N+1$ clusters can attract each other and form a self-bound charge density wave, the properties of which we fully characterize. Our work shows that there are no fundamental obstacles for having self-bound states in fermionic mixtures with zero-range interactions.

  2 citations

• Impact of heavy-quark production measurements in the CT18 global QCD analysis of PDFs

  Marco Guzzi, Pavel Nadolsky, Keping Xie

  SciPost Phys. Proc. 8, 164 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We discuss the impact of heavy-flavor production measurements in semi-inclusive deep inelastic scattering at HERA on the CTEQ-TEA PDFs. In particular, we study the impact of the latest charm and bottom production measurements from the H1 and ZEUS collaborations on the gluon, and the interplay of these measurements with the data ensemble of the recent CT18 global QCD analysis.

  2 citations

• Four no-go theorems on the existence of spin and orbital angular momentum of massless bosons

  Eric Palmerduca, Hong Qin

  SciPost Phys. 18, 188 (2025) · published 16 June 2025 | Toggle abstract · pdf

  The past decades have seen substantial interest in the so-called orbital angular momentum (OAM) of light, driven largely by its diverse range of applications. However, there are fundamental theoretical issues with decomposing the angular momentum of massless particles, such as photons, into spin (SAM) and orbital angular momentum parts. While the angular momentum of massive particles has a natural splitting into the Wigner SAM and OAM, there are numerous proposed splittings for photons and no consensus about which is correct. Moreover, it has been shown that most of the proposed SAM and OAM operators do not satisfy the defining commutation relations of angular momentum operators and are thus not legitimate splittings. Here, we prove that it is generally impossible to split the total angular momentum operator of massless bosons, such as photons and gravitons, into spin and orbital parts. We prove two further generalizations of this result, showing that there are no SAM-OAM splittings even if (1) the SAM operator generates non-internal symmetries or (2) if one allows the SAM and OAM operators to generate non-SO(3) symmetries.

  2 citations

• On the discrepancy between the FOPT and CIPT approaches for hadronic tau spectral function moments

  Andre H. Hoang, Christoph Regner

  SciPost Phys. Proc. 7, 005 (2022) · published 20 June 2022 | Toggle abstract · pdf

  The discrepancy between the FOPT and CIPT approaches for hadronic tau spectral function moments constitutes the major theoretical uncertainty for strong coupling determinations from tau decay data. We show that the discrepancy can be analytically understood since the Borel representations -- which have been assumed to be identical for both approaches previously -- differ in the presence of IR renormalons. This implies that the OPE condensate corrections are different for both approaches and that the discrepancy may eventually be reconciled. In the talk we explain the difference and some mathematical aspects of the FOPT and CIPT Borel representations and show numerical results.

  2 citations

• The photon content of the proton in the CT18 global analysis

  Keping Xie, T. J. Hobbs, Tie-Jiun Hou, Carl Schmidt, Mengshi Yan, C. -P. Yuan

  SciPost Phys. Proc. 8, 074 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Recently, two photon PDF sets based on implementations of the LUX ansatz into the CT18 global analysis were released. In CT18lux, the photon PDF is calculated directly using the LUX master formula for all scales, $\mu$. In an alternative realization, CT18qed, the photon PDF is initialized at the starting scale, $\mu_0$, using the LUX formulation and evolved to higher scales $\mu(>\mu_0)$ with a combined QED+QCD kernel at $\mathcal{O}(\alpha),~\mathcal{O}(\alpha\alpha_s)$ and $\mathcal{O}(\alpha^2)$. In the small-$x$ region, the photon PDF uncertainty is mainly induced by the quark and gluon PDFs, through the perturbative DIS structure functions. In comparison, the large-$x$ photon uncertainty comes from various low-energy, nonperturbative contributions, including variations of the inelastic structure functions in the resonance and continuum regions, higher-twist and target-mass corrections, and elastic electromagnetic form factors of the proton. We take the production of doubly-charged Higgs pairs, $(H^{++}H^{--})$, as an example of scenarios beyond the Standard Model to illustrate the phenomenological implications of these photon PDFs at the LHC.

  2 citations

• Introduction to Monte Carlo for matrix models

  Raghav G. Jha

  SciPost Phys. Lect. Notes 46 (2022) · published 4 April 2022 | Toggle abstract · pdf

  We consider a wide range of matrix models and study them using the Monte Carlo technique in the large N limit. The results we obtain agree with exact analytic expres- sions and recent numerical bootstrap methods for models with one and two matrices. We then present new results for several unsolved multi-matrix models where no other tool is yet available. In order to encourage an exchange of ideas between different numerical approaches to matrix models, we provide programs in Python that can be easily modified to study potentials other than the ones discussed. These programs were tested on a laptop and took between a few minutes to several hours to finish depending on the model, N, and the required precision.

  2 citations

• Double-J/ψ system in the spotlight of recent LHCb data

  V. Baru, X.-K. Dong, F.-K. Guo, C. Hanhart, A. Nefediev, B.-S. Zou

  SciPost Phys. Proc. 6, 007 (2022) · published 31 May 2022 | Toggle abstract · pdf

  Recently the LHCb Collaboration announced intriguing results on the double-$J/\psi$ production in proton-proton collisions. A coupled-channel interpretation of the measured di-$J/\psi$ spectrum is presented and a possible nature of the proposed near-threshold state $X(6200)$ is discussed.

  2 citations

• Constructing non-Abelian quantum spin liquids using combinatorial gauge symmetry

  Dmitry Green, Claudio Chamon

  SciPost Phys. 15, 067 (2023) · published 22 August 2023 | Toggle abstract · pdf

  We construct Hamiltonians with only 1- and 2-body interactions that exhibit an exact non-Abelian gauge symmetry (specifically, combinatiorial gauge symmetry). Our spin Hamiltonian realizes the quantum double associated to the group of quaternions. It contains only ferromagnetic and anti-ferromagnetic $ZZ$ interactions, plus longitudinal and transverse fields, and therefore is an explicit example of a spin Hamiltonian with no sign problem that realizes a non-Abelian topological phase. In addition to the spin model, we propose a superconducting quantum circuit version with the same symmetry.

  2 citations

• Di-$\pi^0$ correlations in p+p, p+Al and p+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV at STAR

  Xiaoxuan Chu

  SciPost Phys. Proc. 8, 043 (2022) · published 12 July 2022 | Toggle abstract · pdf

  The STAR Collaboration reports measurements of back-to-back azimuthal correlations of di-$\pi^0$ produced at forward pseudorapidity ($2.6<\eta<4.0$) in $p+$$p$, $p+$$\mathrm{Al}$ and $p+$$\mathrm{Au}$ collisions at a center-of-mass energy per nucleon-nucleon pair of 200 GeV. A clear suppression of the correlated away-side yields is observed in $p+$$\mathrm{Au}$ and for the first time in $p+$$\mathrm{Al}$ collisions, compared with the $p$$+$$p$ data. The enhanced suppression found in $p+$$\mathrm{Au}$ with respect to $p+$$\mathrm{Al}$ collisions exhibits the saturation scale ($Q_s^2$) dependence on the mass number~~$A$. The observed suppression of back-to-back pairs as a function of event activity and transverse momentum points to non-linear gluon dynamics arising at high parton densities.

  2 citations

• Codebase release 2.2 for HEJ

  Jeppe R. Andersen, Bertrand Ducloué, Conor Elrick, Hitham Hassan, Andreas Maier, Graeme Nail, Jérémy Paltrinieri, Andreas Papaefstathiou, Jennifer M. Smillie

  SciPost Phys. Codebases 21-r2.2 (2023) · published 6 December 2023 | Toggle abstract · src

  We present version 2.2 of the High Energy Jets (HEJ) Monte Carlo event generator for hadronic scattering processes at high energies. The new version adds support for two further processes of central phenomenological interest, namely the production of a W boson pair with equal charge together with two or more jets and the production of a Higgs boson with at least one jet. Furthermore, a new prediction for charged lepton pair production with high jet multiplicities is provided in the high-energy limit. The accuracy of HEJ 2.2 can be increased further through an enhanced interface to standard predictions based on conventional perturbation theory. We describe all improvements and provide extensive usage examples. HEJ 2.2 can be obtained from https://hej.hepforge.org.

  2 citations