Publications

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ALICE at the LHC and astrophysics: From providing input for the search for antinuclei in space to constraining the equation of state of neutron stars

Alexander Kalweit on behalf of the ALICE collaboration

SciPost Phys. Proc. 13, 022 (2023) · published 29 September 2023 | · pdf

The ALICE experiment at the LHC was originally designed to study the creation of the quark-gluon-plasma in heavy-ion collisions, a new state of matter in which quarks and gluons are not confined into hadrons. More recently, the versatility of both the Large Hadron Collider and the ALICE apparatus have given additionally access to a unique set of nuclear and hadronic physics measurements. The main results from this new and dynamic research area will be presented. The application of these findings to astrophysical challenges, ranging from the equation of state of neutron stars to the search for dark matter in space, will be discussed.
On irregularities in the cosmic ray spectrum of $10^{16}-10^{18}$ eV range

Stanislav P. Knurenko, Igor S. Petrov

SciPost Phys. Proc. 13, 020 (2023) · published 28 September 2023 | · pdf

Existing small, medium and large arrays for the study of cosmic rays of ultra-high energies are aimed for obtaining information about our galaxy and extragalactic space, namely to search and study astronomical objects that produce the flux of relativistic particles. The drift and interaction of such particles with magnetic fields and shock waves taking place in interstellar space causes the same interest. The shape of the energy spectrum of cosmic rays in the energy range $10^{15}-10^{18}$ eV, where the "knee" and the "second knee" are observed, can be formed as a superposition of the partial spectra of various chemical elements. Verification of galactic models, using recent experimental spectral data, makes it possible to study the nature of the galactic and extragalactic components of cosmic rays. The paper presents the result of the energy spectrum of cosmic rays in the range $10^{16}-10^{18}$ eV of measurements obtained with the Small Cherenkov array - a part of the Yakutsk array.
Uncertainty in mean $X_{\rm max}$ from diffractive dissociation estimated using measurements of accelerator experiments

Ken Ohashi, Hiroaki Menjo, Takashi Sako, Yoshitaka Itow

SciPost Phys. Proc. 13, 018 (2023) · published 28 September 2023 | · pdf

Mass composition is important for understanding the origin of ultra-high-energy cosmic rays. However, interpretation of mass composition from air shower experiments is challenging, owing to significant uncertainty in hadronic interaction models adopted in air shower simulation. A particular source of uncertainty is diffractive dissociation, as its measurements in accelerator experiments demonstrated significant systematic uncertainty. In this research, we estimate the uncertainty in $\langle X_{\rm max}\rangle$ from the uncertainty of the measurement of diffractive dissociation by the ALICE experiment. The maximum uncertainty size of the entire air shower was estimated to be $^{+4.0}_{-5.6} \mathrm{g/cm^2}$ for air showers induced by $10^{17}$ eV proton, which is not negligible in the uncertainty of $\langle X_{\rm max}\rangle$ predictions.
NLO inclusive $J/ψ$ photoproduction at large $P_T$ at HERA and the EIC

Carlo Flore, Jean-Philippe Lansberg, Hua-Sheng Shao, Yelyzaveta Yedelkina

SciPost Phys. Proc. 8, 011 (2022) · published 11 July 2022 | · pdf

We study inclusive $J/\psi$ photoproduction at NLO at large $P_T$ at HERA and the EIC. Our computation includes NLO QCD leading-$P_T$ corrections, QED contributions via an off-shell photon as well as those from $J/\psi$+charm channels. For the latter, we employ the variable-flavour-number scheme. Our results are found to agree with the latest HERA data by H1 and provide, for the first time, a reliable estimate of the EIC reach for such a measurement. Finally, we demonstrate the observability of $J/\psi$+charm production and the sensitivy to probe the non-perturbative charm content of the proton at high $x$, also known as intrinsic charm, at the EIC.
A measurement of the proton plus helium spectrum of cosmic rays in the TeV region with HAWC

Juan Carlos Arteaga-Velázquez on behalf of the HAWC collaboration

SciPost Phys. Proc. 13, 015 (2023) · published 28 September 2023 | · pdf

HAWC is an air-shower detector designed to study TeV gamma and cosmic rays. The observatory is composed of a 22000 $m^2$ array of 300 water Cherenkov tanks (4.5 m deep x 7.3 m diameter) with 4 photomultipliers (PMT) each. The instrument registers the number of hit PMTs, the timing information and the total charge at the PMTs during the event. From these data, shower observables such as the arrival direction, the core position at ground, the lateral age and the primary energy are estimated. In this work, we study the distribution of the shower age vs the primary energy of a sample of shower data collected by HAWC from June 2015 to June 2019 and employ a shower-age cut based on predictions of QGSJET-II-04 to separate a subsample of events dominated by H and He primaries. Using these data and a dedicated analysis, we reconstruct the cosmic ray spectrum of H+He from 6 to 158 TeV, which shows the presence of a softening at around 24 TeV with a statistical significance of 4.1$\sigma$.
Measurement of the $t\bar{t}t\bar{t}$ production at 13 TeV with the ATLAS detector at the LHC

Ö. Ogul Öncel

SciPost Phys. Proc. 8, 116 (2022) · published 13 July 2022 | · pdf

Two measurements and their combination for the $t\bar{t}t\bar{t}$ production cross-section analysis using 139 fb$^{-1}$ of proton$-$proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the LHC are presented. The first analysis uses the final states with either one or two opposite-sign leptons (electrons or muons). In the second analysis the final states with either two same-sign or at least three leptons are considered. With an observed (expected) significance of 4.3 (2.4) standard deviations over the background-only hypothesis, the second analysis provides the first evidence for the $t\bar{t}t\bar{t}$ process. No significant deviations from the Standard Model are observed.
A new method to extract the valence transversity distributions

Mauro Anselmino, Raj Kishore, Asmita Mukherjee

SciPost Phys. Proc. 8, 052 (2022) · published 12 July 2022 | · pdf

A new method is suggested for the extraction of $u$-quark and $d$-quark transversity distributions, using single spin asymmetry (SSA) data in semi-inclusive deep inelastic scattering (SIDIS) processes, where they couple to the Collins or the di-hadron fragmentation functions. We discuss a recent suggestion to extract the transversity distribution using the concept of difference asymmetries and their ratios, which avoids the requirement of Collins function. We suggest new measurements, involving ratios of polarized cross-sections, that would directly probe the ratio $h_1^{d_v}/h_1^{u_v}$. We also show some numerical estimates.
Measuring single-top-associated Higgs production at the HL-LHC

Henning Bahl

SciPost Phys. Proc. 8, 010 (2022) · published 11 July 2022 | · pdf

Precision measurements of top-associated Higgs production are an important ingredient to unravel the $\mathcal{CP}$ nature of the Higgs boson. In this work, we constraint the $\mathcal{CP}$ nature of the top-Yukawa coupling taking into account all relevant inclusive and differential Higgs boson measurements. Based upon this fit, we show that it is crucial to disentangle single- and di-top-associated Higgs production for tightening indirect constraints on a $\mathcal{CP}$-odd top-Yukawa coupling in the future. In this context, we propose an analysis strategy for measuring $tH$ production at the HL-LHC without relying on assumptions about the Higgs $\mathcal{CP}$ character.
Integrable deformations of superintegrable quantum circuits

Tamás Gombor, Balázs Pozsgay

SciPost Phys. 16, 114 (2024) · published 26 April 2024 | · pdf

Superintegrable models are very special dynamical systems: they possess more conservation laws than what is necessary for integrability. This severely constrains their dynamical processes, and it often leads to their exact solvability, even in non-equilibrium situations. In this paper we consider special Hamiltonian deformations of superintegrable quantum circuits. The deformations break superintegrability, but they preserve integrability. We focus on a selection of concrete models and show that for each model there is an (at least) one parameter family of integrable deformations. Our most interesting example is the so-called Rule54 model. We show that the model is compatible with a one parameter family of Yang-Baxter integrable spin chains with six-site interaction. Therefore, the Rule54 model does not have a unique integrability structure, instead it lies at the intersection of a family of quantum integrable models.
Limits to gauge coupling in the dark sector of super-heavy dark matter particles from the Pierre Auger Observatory data

Olivier Deligny for the Pierre Auger Collaboration

SciPost Phys. Proc. 13, 013 (2023) · published 28 September 2023 | · pdf

Assuming that the energy density of super-heavy particles matches that of dark matter observed today, tight constraints on the couplings governing the decay process are presented as a function of the particle mass. These constraints are obtained from the lack of signatures that would be suggestive of decaying super-heavy $X$ particles in the data of the Pierre Auger Observatory. In particular, instanton-induced decay processes allow us to derive a bound on the reduced coupling constant of gauge interactions in the dark sector: $\alpha_X \lesssim 0.09$, for $10^{9} \lesssim M_X/\mathrm{GeV} < 10^{19}$. Cosmological aspects for super-heavy dark matter production during the reheating epoch are discussed.

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