Publications

Order by: publication date number of citations

• Opportunities for inclusive diffraction at EIC

  Wojciech Slominski, Nestor Armesto, Paul R. Newman, Anna Stasto

  SciPost Phys. Proc. 8, 069 (2022) · published 12 July 2022 | Toggle abstract · pdf

  The possibilities for inclusive diffraction in the Electron Ion Collider, EIC, in the US, are analyzed. We find that thanks to the excellent forward proton tagging, the EIC will be able to access a wider kinematical range of longitudinal momentum fraction and momentum transfer of the leading proton than at HERA. This opens up the possibility to measure subleading diffractive exchanges. The extended $t$-range would allow the precise extraction of 4-dimensional reduced cross section in diffraction. In addition, the varying beam energy setups at the EIC would allow for precise measurements of the longitudinal diffractive structure function.

• 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.

• National Borders among Families: Removal and ‘Bare Life’ in India

  Salah Punathil

  Mig. Pol. 3, 005 (2024) · published 30 October 2024 | Toggle abstract · pdf

  This paper is about the state-driven process of ‘migrant ‘illegality’ (Genova 2002) and its impact on the life of Bengali speaking residents in the Assam state of India. While the movement of people across borders between India and present-day Bangladesh has been historical and complex, this ethnographic work explores how the state-driven process of migrant illegality and the production of ‘bare life’ have disrupted intimate relations and family life among this population in Assam. While the recent NRC (National Register of Citizens) update in Assam identified 1.9 million people as illegal migrants, there has been bureaucratic enactment of ‘migrant illegality’ by Assam Border Police for the last several years. The institutional procedures, court documents and narratives of the select cases of ‘detected’ as well as ‘detained’ migrants from ethnographic fieldwork reveal how the absence of formal papers and errors in the family records, kinship relations and property inheritance among the poor migrant families transforms actual citizens to ‘illegal migrants’ in the bureaucratic manoeuvring and reduces them to their ‘bare life’. The paper also shows how prejudice, arbitrariness, and contradictions feed into the bureaucratic process and lead to intense crises among family units, as several families have both Indians and alleged ‘Bangladeshis’ in their homes today. The paper argues that the major consequence of this state-driven ‘migrant illegality’ in the last two decades has been the creation of national borders among families, unsettling intimate relations and shared spaces.

• Some recent results on renormalization-group properties of quantum field theories

  Robert Shrock

  SciPost Phys. Proc. 6, 005 (2022) · published 31 May 2022 | Toggle abstract · pdf

  We discuss some higher-loop studies of renormalization-group flows and fixed points in various quantum field theories.

• Fluctuations and Selection Bias in 5 and 13 TeV p-p Collisions: Where are the jets?

  Thomas A. Trainor

  SciPost Phys. Proc. 10, 003 (2022) · published 10 August 2022 | Toggle abstract · pdf

  The ALICE collaboration recently reported high-statistics $\bf p_t$ spectra from 5 TeV and 13 TeV p-p collisions with intent to determine the role of jets in high-multiplicity collisions. In the present study a two-component (soft + hard) model (TCM) of hadron production in p-p collisions is applied to ALICE $\bf p_t$ spectra. As in previous TCM studies of A-B collision systems jet and nonjet contributions to $\bf p_t$ spectra are accurately separated over the entire $\bf p_t$ acceptance. The statistical significance of data-model differences is established leading to insights concerning selection bias and spectrum model validity.

• New 2- and 3-loop heavy flavor corrections to unpolarized and polarized deep-inelastic scattering

  Jakob Ablinger, Johannes Blümlein, Abilio De Freitas, Marco Saragnese, Carsten Schneider, Kay Schoenwald

  SciPost Phys. Proc. 8, 137 (2022) · published 14 July 2022 | Toggle abstract · pdf

  A survey is given on the new 2– and 3–loop results for the heavy flavor contributions to deep–inelastic scattering in the unpolarized and the polarized case. We also discuss related new mathematical aspects applied in these calculations.

• The droplet formation-dissolution transition in different ensembles: Finite-size scaling from two perspectives

  Franz Paul Spitzner, Johannes Zierenberg, Wolfhard Janke

  SciPost Phys. 5, 062 (2018) · published 13 December 2018 | Toggle abstract · pdf

  The formation and dissolution of a droplet is an important mechanism related to various nucleation phenomena. Here, we address the droplet formation-dissolution transition in a two-dimensional Lennard-Jones gas to demonstrate a consistent finite-size scaling approach from two perspectives using orthogonal control parameters. For the canonical ensemble, this means that we fix the temperature while varying the density and vice versa. Using specialised parallel multicanonical methods for both cases, we confirm analytical predictions at fixed temperature (rigorously only proven for lattice systems) and corresponding scaling predictions from expansions at fixed density. Importantly, our methodological approach provides us with reference quantities from the grand canonical ensemble that enter the analytical predictions. Our orthogonal finite-size scaling setup can be exploited for theoretical and experimental investigations of general nucleation phenomena - if one identifies the corresponding reference ensemble and adapts the theory accordingly. In this case, our numerical approach can be readily translated to the corresponding ensembles and thereby proves very useful for numerical studies of equilibrium droplet formation, in general.

• 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.

• Tapered amplifier laser with frequency-shifted feedback

  A. Bayerle, S. Tzanova, P. Vlaar, B. Pasquiou, F. Schreck

  SciPost Phys. 1, 002 (2016) · published 22 October 2016 | Toggle abstract · pdf

  We present a frequency-shifted feedback (FSF) laser based on a tapered amplifier. The laser operates as a coherent broadband source with up to 370GHz spectral width and 2.3us coherence time. If the FSF laser is seeded by a continuous-wave laser a frequency comb spanning the output spectrum appears in addition to the broadband emission. The laser has an output power of 280mW and a center wavelength of 780nm. The ease and flexibility of use of tapered amplifiers makes our FSF laser attractive for a wide range of applications, especially in metrology.

• Muon measurements at the Pierre Auger Observatory

  Dariusz Góra

  SciPost Phys. Proc. 15, 020 (2024) · published 3 April 2024 | Toggle abstract · pdf

  The Pierre Auger Observatory is the world's largest detector for observation of ultra-high-energy cosmic rays (UHECRs) (above the energy of $10^{17}$ eV). It consists of a Fluorescence Detector (FD) and an array of particle detectors known as the Surface Detector (SD). Observations of extensive air showers by the Observatory can be used to probe hadronic interactions at high energy, in a kinematic and energy region inaccessible to experiments at man-made accelerators and to measure the muon component of the shower. Air showers induced by different primaries have different muon contents. With increasing mass of the primary cosmic ray particle, it is expected that the muon content in the corresponding air showers should also increase. Therefore, the determination of the muon component in the air shower is crucial to infer the mass of the primary particle. This is a key ingredient in the searches conducted to pinpoint the sources of UHECRs. Recent results obtained from the Pierre Auger Observatory and other experiments indicate that all the shower simulations underestimate the number of muons in the showers compared to the data. This is the so-called muon deficit. In this paper we briefly review the muon measurements, and present in more detail recent results on fluctuations in the muon number. These results provide new insights into the origin of the muon deficit in air shower simulations and constrain the models of hadronic interactions at ultrahigh energies. With the current design of the surface detectors it is also difficult to reliably separate the contributions of muons to the SD signal from the contributions of photons, electrons, and positrons. Therefore, we also present a new method to extract the muon component of the signal time traces recorded by each SD station using recurrent neural networks. The combination of such algorithms, with the future data collected by the upgraded Pierre Auger Observatory, will be a major step forward, as we are likely to achieve an unprecedented resolution in mass estimation on an event-by-event basis.