Publications

Order by: publication date number of citations

• Probing quantum entanglement and collectivity effects in e+p collisions at HERA H1

  Chuan Sun

  SciPost Phys. Proc. 8, 147 (2022) · published 14 July 2022 | Toggle abstract · pdf

  Charged particle multiplicity spectra are measured at HERA H1 in DIS process at 319 GeV. The hadron entropy determined from the multiplicity spectra is compared to the gluon entropy predicted from a quantum-entanglement model. On the other hand, observed collective behaviours in high multiplicity pA, pp and ultra-peripheral PbPb collisions at RHIC and LHC motivate a study in ep collisions. Two- and multi-particle correlations are studied in DIS, as well as photoproduction events with collision energy <Wγp>~270 GeV.

• Transverse spin asymmetries for inclusive $\rho^0$ production in SIDIS at COMPASS

  A. Kerbizi

  SciPost Phys. Proc. 8, 146 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The production of vector mesons in SIDIS is a particularly interesting channel to study the polarized fragmentation and related phenomena. Preliminary COMPASS results for the first measurement of inclusive $\rho^0$ Collins and Sivers transverse-spin asymmetries are presented here for the first time. The analysis is based on the data-set collected by COMPASS in $2010$ using a $160\, \rm{GeV}/c$ $\mu^+$ beam and a transversely polarized $NH_3$ target. The asymmetries are extracted as function of Bjorken-$x$, of the total transverse momentum of the oppositely charged hadron pair and of the fraction of available energy $z$ carried by the pair. Indications for positive Collins and Sivers asymmetries are obtained as expected from models.

• Prospects for diffractive dijet photoproduction at the EIC

  V. Guzey, M. Klasen

  SciPost Phys. Proc. 8, 142 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We discuss the prospects of diffractive dijet photoproduction at the EIC to distinguish different fits of diffractive proton PDFs, different schemes of factorization breaking, to determine diffractive nuclear PDFs and pion PDFs from leading neutron production.

• First indication on self-similarity of strangeness production in Au+Au collisions at RHIC: Search for signature of phase transition in nuclear matter

  M. V. Tokarev, I. Zborovsky

  SciPost Phys. Proc. 10, 035 (2022) · published 11 August 2022 | Toggle abstract · pdf

  New results of analysis of $K^0_S-$meson spectra measured over a wide range of energy $\sqrt {s_{NN}}=7.7-200$ GeV and centrality in $Au+Au$ collisions by the STAR Collaboration at RHIC using the $z$-scaling approach are presented. Indication on self-similarity of fractal structure of nuclei and fragmentation processes with $K^0_S$ probe is demonstrated. The energy loss as a function of the collision energy, centrality and transverse momentum of the inclusive strange meson is estimated.

• Rigorous reconstruction of gluon propagator in the presence of complex singularities

  Yui Hayashi, Kei-Ichi Kondo

  SciPost Phys. Proc. 6, 017 (2022) · published 31 May 2022 | Toggle abstract · pdf

  It has been suggested that the Landau-gauge gluon propagator has complex singularities, which invalidates the K\"all\'en-Lehmann spectral representation. Since such singularities are beyond the standard formalism of quantum field theory, the reconstruction of Minkowski propagators from Euclidean propagators has to be carefully examined for their interpretation. In this talk, we present rigorous results on this reconstruction in the presence of complex singularities. As a result, the analytically continued Wightman function is holomorphic in the usual tube, and the Lorentz symmetry and locality are kept valid. On the other hand, the Wightman function on the Minkowski spacetime is a non-tempered distribution and violates the positivity condition. Finally, we discuss an interpretation and implications of complex singularities in quantum theories, arguing that complex singularities correspond to zero-norm confined states.

• Measurements of charm production in pp collisions with ALICE

  Tiantian Cheng

  SciPost Phys. Proc. 10, 030 (2022) · published 11 August 2022 | Toggle abstract · pdf

  The production of charm-hadrons at midrapidity in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV was recently measured by the ALICE Collaboration. The results show that the baryon-to-meson yield ratios differ from predictions where the hadronisation has been tuned to measurements obtained in $\rm e^{+}e^{-}$ and ep collisions for different charm-baryon species. These observations suggest that the charm fragmentation fractions are not universal and that the baryon-to-meson ratio depends on the collision systems. The results are compared to the predictions from Monte Carlo event generators and theoretical calculations.

• Inclusive decays of heavy quark hybrids

  Abhishek Mohapatra

  SciPost Phys. Proc. 6, 008 (2022) · published 31 May 2022 | Toggle abstract · pdf

  In order to understand the nature of the XYZ particles, theoretical predictions of the various XYZ decay modes are essential. In this work, we focus on the semi-inclusive decays of heavy quarkonium hybrids into traditional quarkonium in the EFT framework. We begin with weakly coupled potential NRQCD effective theory that describes systems with two heavy quarks and incorporates multipole expansions and use it to develop a Born-Oppenheimer effective theory (BOEFT) to describe the hybrids and compute the semi-inclusive decay rates. We compute both the spin-conserving and spin-flipping decay rates and find that our numerical results of the decay rates are different from the previous studies. We also develop a systematic framework in which the theoretical uncertainty can be systematically improved.

• Inclusive and diffractive dijet photoproduction in ultraperipheral heavy ion collisions at the LHC

  V. Guzey, M. Klasen

  SciPost Phys. Proc. 8, 141 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We calculate the cross section of inclusive dijet photoproduction in ultraperipheral collisions (UPCs) of heavy ions at the CERN Large Hadron Collider using next-to-leading order perturbative QCD and demonstrate that it provides a good description of the ATLAS data. We study the role of this data in constraining nuclear parton distribution functions (nPDFs) using the Bayesian reweighting technique and find that it can reduce current uncertainties of nPDFs at small $x$ by a factor of 2. We also make predictions for diffractive dijet photoproduction in UPCs and examine its potential to shed light on the disputed mechanism of QCD factorization breaking in diffraction.

• Measurements of $W$ and $Z/γ^*$ cross sections and their ratios in $pp$ collisions at STAR

  Jae Nam

  SciPost Phys. Proc. 8, 140 (2022) · published 14 July 2022 | Toggle abstract · pdf

  While the unpolarized parton distribution functions of the valence quarks ($d$ and $u$) are well determined from DIS experiments, the sea quark counterparts, $\bar{d}$ and $\bar{u}$, are much less constrained, in particular, near the valence region. Measurements of $W^+/W^-$ production ratio in $pp$ collider experiments, such as the STAR experiment at RHIC, can probe the $\bar{d}/\bar{u}$ ratio at a large $Q^2$ set by the $W$ mass. These proceedings will discuss recent results of $W$ and $Z$ cross-section measurements using the STAR $pp$ collision data at a center-of-mass energy of $\sqrt{s} = 500/510\;\mathrm{GeV}$ collected in 2011, 2012, 2013 and 2017.

• Reduction in radioactivity-induced backgrounds using a novel active veto detector for rare event search experiments

  Mouli Chaudhuri, Andrew Jastram, Glenn Agnolet, Samir Banik, Hao Chen, Vijay Iyer, Varchaswi K. S. Kashyap, Andrew Kubik, Matthew Lee, Rupak Mahapatra, Sandro Maludze, Nader Mirabolfathi, Nityasa Mishra, Bedangadas Mohanty, Himangshu Neog, Mark Platt

  SciPost Phys. Proc. 12, 017 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The results of a newly developed annular cryogenic phonon-mediated active veto detector are discussed which shows a significant reduction of radioactivity-induced backgrounds in rare event search experiments. The veto detector is made up of germanium weighing $\sim$500 g with an outer diameter of 76 mm and an inner diameter of 28 mm. The detector can host a 25 mm diameter germanium inner target detector of mass $\sim$10 g. A GEANT4 simulation with the active veto and inner target detector shows a gamma background reduction of 50 - 80% which is further improved (> 90%) with 4$\pi$ veto coverage. Experimental measurements with the detector assembly agree well with the simulation.