Publications

Order by: publication date number of citations

• 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 | Toggle abstract · 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.

• Recent results from LHCb for astroparticle physics

  Hans Dembinski on behalf of the LHCb collaboration

  SciPost Phys. Proc. 13, 016 (2023) · published 28 September 2023 | Toggle abstract · pdf

  The LHCb experiment is a general-purpose forward spectrometer designed for the study of heavy flavour physics at the LHC. The acceptance in the pseudorapidity range $2 < \eta < 5$ with full tracking and particle identification capabilities down to very small transverse momentum make LHCb also ideal to study hadron production in the forward region. Measuring and modelling these processes is essential for the simulation of interactions of high-energy cosmic rays with matter, like Earth's atmosphere or the interstellar medium. We present recently published analyses from the LHCb collaboration relevant for this application.

• Correlations between azimuthal asymmetries and multiplicity and mean transverse momentum in small collisions systems in the CGC

  Tolga Altinoluk, Néstor Armesto, Alex Kovner, Michael Lublinsky, Vladimir V. Skokov

  SciPost Phys. Proc. 8, 051 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Considering a dilute-dense situation suitable for pA collisions, we compute in the Color Glass Condensate the correlation between azimuthal asymmetries, specifically the squared second Fourier coefficient $v_2^2$, and the total multiplicity in the event. We also analyse the correlation between $v_2^2$ and the mean squared transverse momentum of particles in the event. In both cases, we find that the correlations are generally very small, consistent with the observations. We also note an interesting sharp change in the value of $v_2^2$ and its correlations as a function of the width of the transverse momentum bin, related with a change of the dominance of Bose and HBT quantum correlations.

• 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 | Toggle abstract · 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.

• Results on high energy galactic cosmic rays from the DAMPE space mission

  Leandro Silveri on behalf of the DAMPE Collaboration

  SciPost Phys. Proc. 13, 012 (2023) · published 28 September 2023 | Toggle abstract · pdf

  DAMPE (Dark Matter Particle Explorer) is a satellite-born experiment launched in 2015 in a sun-synchronous orbit at 500 km altitude, and it has been taking data in stable conditions ever since. Its main goals include the spectral measurements up to very high energies, cosmic electrons/positrons and gamma rays up to tens of TeV, and protons and nuclei up to hundreds of TeV. The detector's main features include the 32 radiation lengths deep calorimeter and large geometric acceptance, making DAMPE one of the most powerful space instruments in operation, covering with high statistics and small systematics the high energy frontier up to several hundreds TeV. The results of spectral measurements of different species are shown and discussed.

• Prompt hadroproduction of C-even quarkonia in the light-front $k_T$ -factorization approach

  Wolfgang Schäfer, Izabela Babiarz, Roman Pasechnik, Antoni Szczurek

  SciPost Phys. Proc. 8, 032 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present a new approach for the prompt production of quarkonia which is based on the $k_T$-factorization method. The production of even C-parity quarkonia proceeds via the fusion of two (off-shell) gluons. Especially in the kinematics of the LHCb experiment these processes are thus expected to be a sensitive probe of the small-x gluon distribution. We calculate the relevant off-shell matrix elements in terms of the light-front wave functions of the quarkonium states. We present our results for scalar and pseudoscalar charmonia and discuss photon transition form factors as well as cross sections for prompt hadroproduction. We compare our results for the $\eta_c$ to recent LHCb data.

• Resummation for $tqH$ production

  Matthew Forslund, Nikolaos Kidonakis

  SciPost Phys. Proc. 8, 021 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present results with soft-gluon resummation for the associated production of a single top quark and a Higgs boson. We present analytical results for the higher-order soft-gluon corrections and numerical results for the total cross section and top-quark transverse momentum and rapidity distributions at LHC energies.

• Measurements and searches of Higgs boson production involving fermion couplings with the ATLAS detector

  Shigeki Hirose

  SciPost Phys. Proc. 8, 006 (2022) · published 11 July 2022 | Toggle abstract · pdf

  In the standard model, fermions acquire the mass via the Yukawa interaction. This mechanism can be tested by measuring couplings of the fermions with the Higgs boson. At the ATLAS experiment, the Higgs-fermion coupling measurements became possible thanks to the abundant dataset: the integrated luminosity of 139~fb$^{-1}$ at the centre-of-mass energy of 13~TeV as well as 25~fb$^{-1}$ at 7--8~TeV. This paper presents recent results from measurements of the Higgs boson productions in decays to a fermion pair in the final state with the ATLAS detector.

• Spin Density Matrix Elements for Exclusive $\rho^{0}$ Meson Muoproduction at COMPASS

  W.~Augustyniak

  SciPost Phys. Proc. 8, 073 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Spin density matrix elements were extracted from COMPASS data for exclusive $\rho^{0}$ meson muoproduction on a liquid hydrogen target. The measurement cover the kinematic range of 1.0 (GeV/$c$)$^2$ $< Q^{2} <$ 10.0 (GeV/$c$)$^2$, 5.0 GeV/$c^2$ $< W <$ 17.0 GeV/$c^2$ and 0.01 (GeV/$c$)$^2$ $<p^{2}_{T} < $ 0.5 (GeV/$c$)$^2$. Here, $W$ denotes the mass of the final hadronic system, $Q^{2}$ the virtuality of the exchanged photon and $p_{T}$ the transverse momentum of the $\rho^{0}$ meson with respect to the virtual-photon direction. We observe a violation of s-channel helicity conservation for the transition $\gamma^{*}_{T} \to \rho^{0}_{L}$. Additionally, we find a dominant contribution of the natural-parity-exchange transitions.

• Experimental input from $e^+e^-$ for $a_{\mu}$ light-by-light

  Yuping Guo on behalf of BESIII Collaboration

  SciPost Phys. Proc. 1, 054 (2019) · published 9 May 2019 | Toggle abstract · pdf

  The anomalous magnetic momentum of the muon, $a_{\mu}$, has been measured and calculated with a precision up to $~0.5$ ppm, but there is a 3 to 4 standard deviations between these two values. The uncertainty in the calculation is dominated by the hadronic part, including the hadronic vacuum polarization and the hadronic light-by-light. The meson transition form factors and the helicity amplitudes can be used as input or constraint to the calculation of the hadronic light-by-light contribution. Latest experimental studies of the transition form factors of $\pi^0$, $\eta$, and $\eta^{*}$ and the cross-section of $\gamma\gamma^*\to\pi^+\pi-$from $e^+e^-$ collider are presented.