Publications

Order by: publication date number of citations

• Longitudinal Z-boson polarization and the Higgs boson production cross-section

  Simone Amoroso

  SciPost Phys. Proc. 8, 016 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Lepton pairs are produced copiously in high-energy hadron collisions via electroweak gauge boson exchange, and are one of the most precisely measured final states in proton- proton collisions at the Large Hadron Collider (LHC). We propose that measurements of lepton angular distributions can be used to improve the accuracy of theoretical predic- tions for Higgs boson production cross sections at the LHC. To this end, we exploit the sensitivity of the lepton angular coefficient associated with the longitudinal Z-boson polarization to the parton density function (PDF) for gluons resolved from the incoming protons, in order to constrain the Higgs boson cross section from gluon fusion processes. By a detailed numerical analysis using the open-source platform xFitter, we find that high-statistics determinations of the longitudinally polarized angular coefficient at the LHC Run III and high-luminosity HL-LHC improve the PDF systematics of the Higgs boson cross section predictions by 50 % over a broad range of Higgs boson rapidities.

• Hard color-singlet exchange in dijet events in proton-proton collisions at $\sqrt{s} = 13$ TeV

  Cristian Baldenegro Barrera

  SciPost Phys. Proc. 8, 015 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present a measurement of events with two jets separated by a pseudorapidity gap (jet-gap-jet). The signature is expected from hard color-singlet exchange. The jets are reconstructed with the CMS detector. The highest $p_\text{T}$ jets have $p_\text{T}^\text{jet1,2} > 40$ GeV, with $1.4 < |\eta^\text{jet1,2}| < 4.7$ and $\eta^\text{jet1} \eta^\text{jet2} < 0$. We measure the fraction of color-singlet exchange dijet events, $f_\text{CSE}$, and compare it to previous measurements and to predictions. We also study jet-gap-jet events where the colliding protons remain intact and are detected with the Roman pots of TOTEM. A larger fraction $f_\text{CSE}$ is found in the latter subsample.

• Transverse Single-Spin Asymmetries of Midrapidity Direct Photons and Neutral Mesons at PHENIX

  Nicole Lewis

  SciPost Phys. Proc. 8, 009 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Results are presented for the transverse single-spin asymmetries of direct photons, neutral pions, and eta mesons for $|\eta|<0.35$ from $p^\uparrow + p$ collisions with $\sqrt{s} = 200$ GeV at PHENIX. As hadrons, $\pi^0$ and $\eta$ mesons are sensitive to both initial- and final-state effects and at midrapidity probe the dynamics of gluons along with a mix of quark flavors. Because direct photon production does not include hadronization, the direct photon TSSA is only sensitive to initial-state effects and at midrapidity provides a clean probe of the gluon dynamics in transversely polarized protons. All three of these results will help constrain the collinear twist-3 trigluon correlation function as well as the gluon Sivers function, improving our knowledge of spin-dependent gluon dynamics in QCD.

• Study of the hyperon-nucleon interaction via final-state interactions in exclusive reactions

  Nicholas Zachariou, Daniel Watts, Yordanka Ilieva

  SciPost Phys. Proc. 3, 026 (2020) · published 25 February 2020 | Toggle abstract · pdf

  A novel approach that allows access to long-sought information on the Hyperon-Nucleon (YN) interaction was developed by producing a hyperon beam within a few-body nuclear system, and studying final-state interactions. The determination of polarisation observables, and specifically the beam spin asymmetry, in exclusive reactions allows a detailed study of the various final-state interactions and provides us with the tools needed to isolate kinematic regimes where the YN interaction dominates. High-statistics data collected using the CLAS detector housed in Hall-B of the Thomas Jefferson laboratory allows us to obtain a large set of polarisation observables and place stringent constraints on the underlying dynamics of the YN interaction.

• Measurement of the $\textit{CP}$ structure of the Higgs-tau Yukawa coupling

  Vinaya Krishnan MB

  SciPost Phys. Proc. 8, 008 (2022) · published 11 July 2022 | Toggle abstract · pdf

  The CMS experiment at the LHC has performed the first measurement of the CP structure of the Yukawa coupling between the Higgs boson and tau leptons. The measurement is based on data collected in proton-proton collisions at $\sqrt{s} = 13$ TeV during 2016-18, corresponding to an integrated luminosity of $137\text{ fb}^{-1}$. The analysis utilizes the angular correlation between the decay planes of tau leptons produced in Higgs boson decays, where dedicated analysis techniques are used to optimise the reconstruction of tau decay planes. The measured value of the CP mixing angle is $4\pm17^{\circ}$, at $68\%$ confidence level. The pure $\textit{CP-}$odd hypothesis is excluded by $3.2$ standard deviations. The analysis strategies and the results of the measurement are presented.

• Rapid detection of phase transitions from Monte Carlo samples before equilibrium

  Jiewei Ding, Ho-Kin Tang, Wing Chi Yu

  SciPost Phys. 13, 057 (2022) · published 9 September 2022 | Toggle abstract · pdf

  We found that Bidirectional LSTM and Transformer can classify different phases of condensed matter models and determine the phase transition points by learning features in the Monte Carlo raw data before equilibrium. Our method can significantly reduce the time and computational resources required for probing phase transitions as compared to the conventional Monte Carlo simulation. We also provide evidence that the method is robust and the performance of the deep learning model is insensitive to the type of input data (we tested spin configurations of classical models and green functions of a quantum model), and it also performs well in detecting Kosterlitz–Thouless phase transitions.

• Alibis of Exclusion: The role of ethnic economies in the differentiated inclusion of refugees in Berlin

  Jagat Sohail

  Mig. Pol. 2, 002 (2023) · published 11 July 2023 | Toggle abstract · pdf

  Neoliberal transformations in the field of asylum in Germany have, since 2016, placed an emphasis on labour market participation as the primary way through which refugees can establish long-term residence claims. Yet, while new arrivals are increasingly expected to rapidly integrate into this market, they are often armed with differential and precarious legal statuses which overwhelmingly determine the spheres of economic activity refugees can enter. This is especially true for the ever increasing number of rejected asylum seekers who are temporarily “tolerated”, for whom the only path to residence requires that they display their value as economic subjects to the German state. Based on ethnographic fieldwork conducted in Berlin between 2017 and 2020, I argue that, armed with little other than their cultural identities and networks, many refugees heavily relied on co-ethnic relationships to facilitate their participation in the labour market. The result is a displacement of the management of new diversity to ethnic economies, a move that disavows the marginalising consequences of the neoliberal transformations refugees are subject to. By masking a relationship between recently arrived migrants and the German economy and society as a relationship between migrants themselves, I argue that these practices work as alibis of exclusion.

• Soliton confinement in the double sine-Gordon model

  Sergei Rutkevich

  SciPost Phys. 16, 042 (2024) · published 7 February 2024 | Toggle abstract · pdf

  The double sine-Gordon field theory in the weak confinement regime is studied. It represents the small non-integrable deformation of the standard sine-Gordon model caused by the cosine perturbation with the frequency reduced by the factor of 2. This perturbation leads to the confinement of the sine-Gordon solitons, which become coupled into the 'meson' bound states. We classify the meson states in the weak confinement regime, and obtain three asymptotic expansions for their masses, which can be used in different regions of the model parameters. It is shown, that the sine-Gordon breathers, slightly deformed by the perturbation term, transform into the mesons upon increase of the sine-Gordon coupling constant.

• Ionization efficiency at sub-keV energies for crystals and noble liquids

  Youssef Sarkis, Alexis A. Aguilar-Arevalo, Juan Carlos D'Olivo

  SciPost Phys. Proc. 12, 008 (2023) · published 3 July 2023 | Toggle abstract · pdf

  We study the ionization and light yields produced by nuclear recoils at low energies in pure crystals and noble liquids in the context of Lindhard's integral equation, incorporating the effects of binding energy, improved modeling of the electronic stopping, and electronic straggling. We consider three different models for the electronic stopping power that incorporate Coulomb repulsion effects at low energies, and Bohr electronic stripping for high energies. Finally, we discuss possible new effects near threshold.

• High-energy logarithmic corrections to the QCD component of same-sign W-pair production

  Jeppe R. Andersen, Bertrand Ducloué, Conor Elrick, Andreas Maier, Graeme Nail, Jennifer M. Smillie

  SciPost Phys. Proc. 8, 129 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We describe the calculation of the QCD contribution to same-sign $W$-pair production, $pp\to e^\pm \nu_e \mu^\pm \nu_\mu jj$, resumming all contributions scaling as $\alpha_W^4 \alpha_s^{2+k}\log^k(\hat s/p_\perp^2)$ [arXiv:2107.06818]. These leading logarithmic contributions are enhanced by typical cuts used for Vector Boson Scattering (VBS) studies. We show that while the cross sections are little affected by these corrections, other more exclusive observables relevant for experimental studies are affected more significantly.