Publications

Order by: publication date number of citations

• M5-brane prongs, string soliton bound states and wall-crossing

  Varun Gupta, K. Narayan

  SciPost Phys. Core 8, 004 (2025) · published 13 January 2025 | Toggle abstract · pdf

  We study Abelian M5-brane field configurations representing BPS bound states of self-dual string solitons whose locations correspond to the endlines of M2-branes ending on the M5-branes. The BPS equations are obtained from appropriate Bogomolny completion of the effective Abelian low energy functional with two transverse scalars, using two vectors representing the directions along which these endline strings extend. Then we impose boundary conditions on the scalars near the string soliton cores. This leads to a molecule-like equilibrium structure of two non-parallel string solitons at fixed transverse separations, with the M5-brane "prong" deformations comprising two "spikes", each shaped like a ridge. The resulting picture becomes increasingly accurate as one approaches the wall of marginal stability, on which these states decay. There are various parallels with wall-crossing phenomena for string web configurations obtained from D3-brane deformations.

• Impact of W and Z Production Data and Compatibility of Neutrino DIS Data in Nuclear Parton Distribution Functions

  K. F. Muzakka, P. Duwentäster, T. J. Hobbs, T. Ježo, M. Klasen, K. Kovařík, A. Kusina, J. G. Morfín, F. I. Olness, R. Ruiz, I. Schienbein, J. Y. Yu

  SciPost Phys. Proc. 8, 041 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Vector boson production and neutrino deep-inelastic scattering (DIS) data are crucial for constraining the strange quark parton distribution function (PDF) and more generally for flavor decomposition in PDF extractions. We extend the nCTEQ15 nuclear PDFs (nPDFs) by adding the recent $W$ and $Z$ production data from the LHC in a global nPDF fit. The new nPDF set, referred to as nCTEQ15WZ, is used as a starting point for a follow-up study in which we assess the compatibility of neutrino DIS data with charged lepton DIS data. Specifically, we re-analyze neutrino DIS data from NuTeV, Chorus, and CDHSW, as well as dimuon data from CCFR and NuTeV. To scrutinize the level of compatibility, different kinematic regions of the neutrino data are investigated. Fits to the neutrino data alone and a preliminary global fit are performed and compared to nCTEQ15WZ.

• Phase space compression of a positive muon beam in two spatial dimensions

  A. Antognini, N. J. Ayres, I. Belosevic, V. Bondar, A. Eggenberger, M. Hildebrandt, R. Iwai, K. Kirch, A. Knecht, G. Lospalluto, J. Nuber, A. Papa, M. Sakurai, I. Solovyev, D. Taqqu, T. Yan

  SciPost Phys. Core 8, 071 (2025) · published 20 October 2025 | Toggle abstract · pdf

  We present the first demonstration of simultaneous phase space compression in two spatial dimensions of a positive muon beam, the first stage of the novel high-brightness muon beam under development by the muCool collaboration at the Paul Scherrer Institute. The keV-energy, sub-mm size beam would enable a factor $10^5$ improvement in brightness for precision $\mu$SR, and atomic and particle physics measurements with positive muons. This compression is achieved within a cryogenic helium gas target with a strong density gradient, placed in a homogeneous magnetic field, under the influence of a complex electric field. In the next phase, the muon beam will be extracted into vacuum.

• The study of hadron properties and structure in high energy multi-production processes

  Shi-Yuan Li

  SciPost Phys. Proc. 10, 039 (2022) · published 11 August 2022 | Toggle abstract · pdf

  In high energy scattering, the multi-production process is unique in its relevance to the total cross section and in its global properties, such as rapidity and other kinematic distributions. If there is a hard interaction, the jet rate and structure is a good arena for perturbative quantum chromodynamics. However, once any hadron is specified, its properties and structure must make sense, while the global and/or perturbative chromodynamic mechanism still can put important constraints. The relation of the hadron’s properties and structure with its production cross section, distribution etc. can be much more complex than its decay width. On the one hand there are many difficulties and challenges in the calculations, while on the other hand, the production process provides a unique way to study the details of properties and structure of the hadron, which is beyond the approach of its decay process. Here I review our works on such topics in recent years, mainly on the multi-quark state production in multi-production processes and the Bethe-Salpeter wave function in exclusive processes. For the former, I emphasize the unitarity of the hadronization process and relevant models, so that almost no multi-quark state is observed in multi-production processes. I also address how to calculate hadron molecule production in multi-production processes. The most recently observed T+cc is also stated with its relevance to colour and baryon number fluctuation of the preconfinement clusters. For the latter, I emphasize the Dirac structure of the hadron-quark coupling vertex.

• FASER experiment and first results from LHC run 3

  Umut Kose, on behalf of FASER collaboration

  SciPost Phys. Proc. 17, 018 (2025) · published 23 July 2025 | Toggle abstract · pdf

  FASER is designed to search for light, extremely weakly interacting and long-lived beyond standard model particles at the CERN Large Hadron Collider. Such particles, e.g., dark photons, may be produced in the high-energy proton-proton collisions at the ATLAS interaction point and then decay to visible particles in FASER, which is placed 480 m downstream and aligned with the collision axis line-of-sight. The detector covers a previously unexplored range of pseudorapidity larger than 8.8, which allows it to have sensitivity to new physics in the far-forward region. FASER also has a sub-detector called FASER$\nu$, which is specifically designed to detect and investigate high-energy collider neutrino interactions in the TeV regime, extending current cross-section measurements. In this proceeding, the FASER detector and present recent results obtained during LHC Run 3 will be introduced.

• The two-loop radiative gluon jet function for $gg\to h$ via a light quark loop

  Marvin Schnubel

  SciPost Phys. Proc. 7, 039 (2022) · published 22 June 2022 | Toggle abstract · pdf

  The Higgs-boson production channel $gg\to h$ mediated by light-quark loops receives large logarithmic corrections in QCD, which can be resummed using factorization formulae derived in soft-collinear effective theory. In these factorization formulae the radiative gluon jet function appears, which is a central object in the study of factorization beyond the leading order in scale ratios. We calculate this function at two-loop order for the first time and present the subtleties that come along with this.

• PMC$_\infty$: Infinite-Order Scale-Setting method using the Principle of Maximum Conformality and preserving the Intrinsic Conformality

  Leonardo Di Giustino, Stanley J. Brodsky, Xing-Gang Wu, Sheng-Quan Wang

  SciPost Phys. Proc. 7, 038 (2022) · published 21 June 2022 | Toggle abstract · pdf

  We show results for Thrust and C-parameter in $e^+ e^-$ annihilation to 3 jets obtained using the recently developed new method for eliminating the scale ambiguity and the scheme dependence in pQCD namely the Infinite-Order Scale-Setting method using the Principle of Maximum Conformality (PMC$_\infty$). This method preserves an important underlying property of gauge theories: intrinsic Conformality (iCF). It leads to a remarkably efficient method to eliminate the conventional renormalization scale ambiguity at any order in pQCD. A comparison with Conventional Scale Setting method (CSS) is also shown.

• Backward-Angle (u-Channel) Meson Production from JLab 12~GeV Hall C to EIC

  Wenliang B. Li

  SciPost Phys. Proc. 8, 036 (2022) · published 12 July 2022 | Toggle abstract · pdf

  The recent exclusive backward-angle electroproduction of omega from Jefferson Lab Hall C electron-proton fixed-target scattering experiments above the resonance region hints at a new domain of applicability of QCD factorization in a unique u-channel kinematics regime. Thanks to this effort, the interest in studying nucleon structure through u-channel meson production observables has grown significantly. In the fixed target configuration, theu-channel meson electroproduction observables feature a unique interaction picture: the target proton absorbs nearly all momentum induced by virtual photons and recoils forward, while the produced mesons (such as omega or pions) are left behind almost at rest near the target station. In this presentation, We provide a summary of the key observations of the existing u-channel meson production results, update-to-date theory insights, and a path to further exploration from JLab 12 GeV Hall C program to the future Electron-Ion Colliders

• Precision $e^-$ beam polarimetry at an $e^+e^-$ B factory using tau-pair events

  Caleb Miller

  SciPost Phys. Proc. 17, 011 (2025) · published 23 July 2025 | Toggle abstract · pdf

  A novel technique for measuring the average beam polarization in $e^+e^-$ collisions, known as Tau Polarimetry, has been developed by the BABAR collaboration. This technique makes use of the relationship between the polarization of the beams, the resulting polarization of the $\tau^+\tau^-$ produced, and the kinematics of the decay products. Using this technique BABAR has measured the average $e^-$ beam polarization of PEP-II to be 0.0034 $± 0.0024_{stat} ± 0.0029_{sys}$. This technique is expected to be used at Belle II after a proposed polarization upgrade as the most precise method with which beam polarization can be determined.

• NLO collinear factorization of large mass diphoton photoproduction amplitude

  Oskar Grocholski, Bernard Pire, Paweł Sznajder, Lech Szymanowski, Jakub Wagner

  SciPost Phys. Proc. 8, 078 (2022) · published 12 July 2022 | Toggle abstract · pdf

  We calculate large mass diphoton exclusive photoproduction in the framework of collinear QCD factorization at next to leading order in {\alpha}s and at leading twist. Collinear divergences of the coefficient function are absorbed by the evolution of the generalized parton distributions (GPDs). This result enlarges the existing factorization proofs to 2 -> 3 processes, opening new reactions to a trustable extraction of GPDs.