# Widok zawartości stron

## Aktualności

# Blogi

Dear All,

We have the pleasure of inviting you to the Particle Theory Seminar on Tuesday, December 12 at 12:15, which will be given by

Dimitri Colferai (Universita di Firenze and INFN Firenze)

entitled

„Small-x resummation of photon impact factors and virtual photon scattering at high energies".

Abstract:

After a brief introduction on the peculiarities of QCD in the high-energy regime and the BFKL approach for its description, we proceed to the theoretical analysis of virtual photon scattering. Here, the crucial theoretical objects are the photon impact factors and the BFKL gluon Green's function, which up to now are known in leading and next-to-leading logarithmic approximation. We improve the theoretical description of the virtual photon cross section by performing the renormalization group improved collinear resummation of impact factors and Green's function. Our analysis is consistent with previous impact factor calculations at NLO, apart from a new term proportional to CF that we find for the longitudinal polarization. Finally, we use the resummed cross section to compare with the LEP data and with previous calculations. The resummed result is lower than the leading logarithmic approximation but higher than the pure next-to-leading one, and is consistent with the experimental data.

Based on arXiv: hep-ph 2311.07443.

The speaker will be remote, local participants are invited to meet in the seminar room D-2-02.

Dear All,

We have the pleasure of inviting you to the Particle Theory Seminar on Tuesday, December 5 at 12:15, which will be given by

Rene Poncelet (IFJ PAN)

entitled

„ Precision phenomenology with heavy-flavour jets at the LHC".

Abstract:

Jets are a staple of the research program at high-energy hadron colliders. As suitably defined sets of highly-energetic particles, they constitute a useful tool to establish a link between Quantum Chromodynamics (QCD) of quarks and gluons and the realm of actual strongly-interacting particles, baryons and mesons. Besides the general importance of jets for collider phenomenology, there is a growing interest in studying jet substructure in order to disentangle various QCD effects governing jet dynamics. Final states with jets identified to originate from heavy quarks play a vital role, for example, in understanding the process of heavy-quark fragmentation and the contents of protons at high energy. In this talk I will discuss fixed-order NNLO QCD phenomenology, comparisons thereof to data and infrared-safe flavoured jet algorithms, a non-trivial ingredient in defining useful collider observables.

The speaker will be on-site, local participants are invited to meet in the seminar room D-2-02.

Dear All,

We have the pleasure of inviting you to the Particle Theory Seminar on Tuesday, November 28 at 12:15, which will be given by

Pan Kessel (Genentech Roche)

entitled

„Generative Model for Sampling in Theoretical Physics".

Abstract:

An important problem that arises throughout theoretical physics is the following: given an unnormalized distribution (or energy), we want to sample from this distribution. Various Monte-Carlo algorithms exist to facilitate sampling with asymptotic guarantees. However, they can suffer from slow mixing and large autocorrelation. In this talk, I will give a brief introduction to deep generative models and discuss why they have the potential to considerably speed up such sampling problems. I will also discuss the open challenges with this approach. I will mainly focus on lattice field theory applications for illustration.

The speaker will be on-line, local participants are invited to meet in the seminar room D-2-02.

Dear All,

We have the pleasure of inviting you to the Particle Theory Seminar on Tuesday, November 21 at 12:15, which will be given by

Sanjin Benić (University of Zagreb)

entitled

„ Odderon at the EIC from exclusive production of C-even charmonia".

Abstact:

Recently, TOTEM and D0 collaborations announced the discovery of the odderon in the pp vs ppbar elastic cross section difference [1,2]. Our main goal here is to investigate the potential for the odderon detection at the future EIC. This talk is focused on our recent computation [3,4] of exclusive C-even charmonia productions in high-energy electron-proton collisions. The C-even charmonia states serve as a probe of the odderon amplitude in the proton which is an off-forward generalized transverse momentum distribution formed by at least three gluons in a C-odd state. The computation is based on the Color Glass Condensate framework, where we numerically solve the Balitsky- Kovchegov evolution equation for coupled pomeron-odderon system. Our initial conditions are based on a microscopic quark model computation [5] that is an essential ingredient for a proper account of the so-called Donnachie-Landshoff mechanism according to which even a large-|t| scattering would not break up the proton if it involves a three-gluon exchange. Our comprehensive results cover the exclusive production of the eta_c meson [4] and the chi_cJ family (J = 0, 1, 2) [3]. While eta_c was originally suggested already long time ago [6], chi_c was not discussed so far. Due to the large branching ratio to J\Psi+gamma we argue that chi_c should be a more suitable channel for the potential odderon detection at the EIC. In our computation we pay special attention to the interference with the Primakoff process where our model computation fixes the relative phase between the two contributions. We demonstrate how the deviations from the purely Primakoff contribution can be used as a probe of the odderon amplitude in the proton at the EIC.

[1] TOTEM collaboration, Eur. Phys. J. C 80, 91 (2020) [2] D0 collaboration, Phys. Rev. D 86, 012009 (2012) [3] SB, A. Dumitru, A. Kaushik, L. Motyka, T. Stebel, in preparation [4] SB, D. Horvatic, A. Kaushik, E. A. Vivoda, Phys. Rev. D 108 (2023) 7, 074005 [5] A. Dumitru, H. Mantysaari, R. Paatelainen, Phys. Rev. D 107, L011501 (2023) [6] J. Czyzewski, J. Kwiecinski, L. Motyka, and M. Sadzikowski, Phys. Lett. B 398, 400 (1997)

The speaker will be on-site, local participants are invited to meet in the seminar room D-2-02.

Dear All,

We have the pleasure of inviting you to the Particle Theory Seminar on Tuesday, November 14 at 12:15, which will be given by

Farid Taghinavaz (School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran)

entitled

„Relativistic hydrodynamics with phase transitions".

Abstact:

It has been confirmed by many observations that the Quark-Gluon plasma is a new type of matter that is produced after the collisions of heavy ions and in today’s energies it behaves like (almost) perfect fluid. The relativistic hydrodynamics (RH) is an appropriate tool to describe the dynamics of this complicated system near the local equilibrium or even far from equilibrium. However, there has been several unsolved issues by using the RH which one of them is how to employ it or in what extent the RH is valid near the phase transition points. We benefit of the gauge/gravity duality to study the time-dependent perturbations of the dual metric in a short-wave-length limit at a certain phenomenological model, the so called Einstein-Klein-Gordon model. We will examine the radius of convergence of the hydro series near the critical points for various kinds of phase transitions as well as different spin-sectors.

The speaker will be on-site, local participants are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

We have the pleasure of inviting you to the Particle Theory Seminar on Tuesday, November 7 at 12:15, which will be given by

Maxim Nefedov (Universite Paris-Saclay, CNRS)

entitled

„ Curing high-energy instability of quarkonium production cross sections with High-Energy Factorisation".

The speaker will be online, local participants are invited to meet in the seminar room D-2-02.

Dear All,

We have the pleasure to invite you to the Particle Theory Seminar on Tuesday, October 24 at 12:15, which will be given by

James Whitehead (IFJ PAN)

entitled

„The KrkNLO method for NLO parton shower matching".

Abstract:

'Matched' calculations combining the next-to-leading-order (NLO) accuracy of perturbative QCD with the logarithmic resummation of a parton shower are a key workhorse driving LHC phenomenology in the precision era. The KrkNLO method for NLO parton shower matching uses multiplicative reweighting and a convenient choice of PDF factorisation scheme to produce matched NLO + parton shower predictions. By construction, it guarantees positive weights. I will present an introduction to the theory of NLO matching, an overview of the KrkNLO method, and phenomenological results from the implementation of new processes in Herwig 7.

The seminar will be in in-person mode in the seminar room D-2-02, but you can also attend remotely through Zoom.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

We have the pleasure to invite you to the Particle Theory Seminar on Tuesday, October 17 at 12:15, which will be given by

Yizhuang Liu (IFT UJ)

entitled

„ A survey of the heavy-light Sudakov universality class".

The seminar will be in in-person mode in the seminar room D-2-02, but you can also attend remotely through Zoom:

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

We have the pleasure to invite you to the Particle Theory Seminar (together with the Field Theory Department) on Tuesday, October 10 at 14:00 (different time!), which will be given by

Błażej Ruba (University of Copenhagen)

entitled

„Dense and strongly interacting nonrelativistic fermions".

Abstract:

I will discuss estimates of the ground state energy of interacting nonrelativistic fermions obtained using an approximate bosonization method. The new result concerns the strongly coupled regime, which I will compare to the perturbative regime and the critical scaling conventionally called "mean field".

The seminar will be in in-person mode in the seminar room D-2-02, but you can also attend remotely through Zoom:

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

We have the pleasure to invite you to the Particle Theory Seminar on Tuesday, October 3 at 12:15, which will be given by

Steven Bass (CERN)

entitled

„ Cosmology with an emergent particle physics Standard Model“.

The seminar will be in in-person mode in the seminar room D-2-02, but you can also attend remotely through Zoom.

Dear All,

We have the pleasure to invite you to the Particle Theory Seminar on Tuesday, July 4 at 12:15, which will be given by

Asaad Daher (IFJ PAN)

entitled

„Entropy production in spin hydrodynamics“.

The seminar will be in only in in-person mode in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

We have the pleasure to invite you to the Particle Theory Seminar on Tuesday, June 20 at 12:15, which will be given by

Kiminad Mamo (Argonne National Laboratory)

entitled

„Quark and gluon GPDs at finite skewness from strings in holographic QCD“.

Abstract:

In this talk, we present a comprehensive framework for constructing Generalized Parton Distributions (GPDs) by employing holographic QCD in the context of the large Nc limit. The emphasis is on the low-x and finite skewness regimes. Our methodology involves using t-channel string exchanges in soft-wall AdS to extract the spin-j conformal (Gegenbauer) moments of GPDs from the holographic amplitudes associated with exclusive electroproduction processes. These moments are then evolved to higher resolution scales using QCD evolution equations. We demonstrate the applicability of our evolved GPDs (reconstructed from their evolved conformal moments) in the analysis of electroproduction involving neutral rho, phi,and charged rho mesons. Non-perturbative contributions in the s+u channel are also accounted for using holographic QCD, and our findings show good agreement with existing experimental data. Our GPDs offer valuable insights into partonic distributions and serve as a useful resource for future experimental investigations and global data analyses.

The seminar will be in a hybrid mode, local people are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

We have the pleasure to invite you to the Particle Theory Seminar on Tuesday, June 13 at 12:15, which will be given by

Francesco Giacosa (Jan Kochanowski University in Kielce)

entitled

„Neutrino mixing in the interaction picture“.

The seminar will be in a hybrid mode, local people are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

We have the pleasure to invite you to the Particle Theory Seminar on Tuesday, June 6 at 12:15, which will be given by

Andrea Bulgarelli (University of Torino)

entitled

„ Entanglement entropy from non-equilibrium lattice simulations“

Abstract:

“The entanglement entropy is a quantity encoding important features of strongly interacting quantum many-body systems and gauge theories, but its analytical study is still limited to systems with high level of symmetry. This motivates the search for efficient techniques to investigate this quantity numerically, by means of Monte Carlo calculations on the lattice. In this talk, we present a lattice determination of the entropic c-function using a novel algorithm based on Jarzynski's equality: an exact theorem from nonequilibrium statistical mechanics. After presenting benchmark results for the Ising model in two dimensions, where our algorithm successfully reproduces the analytical predictions from conformal field theory, we discuss its generalization to the three dimensional Ising model, for which we were able to extract universal terms beyond the area law. Finally we comment on future applications.”

The seminar will be in a hybrid mode, local people are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on Tuesday, May 30 at 12:15, which will be given by

Maciej Majka, Marcin Zagórski (IFT UJ)

entitled

„ Formation of gene expression patterns in biological systems “

Abstract:

“The development of multicellular organisms is a dynamic process in which cells divide, rearrange, and interpret molecular signals to adopt specific cell fates. This results in the emergence of gene expression patterns, that later on give raise to different body parts and organs. We still lack full understanding of how these patterns could form and remain stable during organism development. In this talk we address this question by considering reaction-diffusion model with two genes interacting via diffusible signaling molecules, controlling the size of their own source regions. By identifying the conservation law describing the number of particles reaching the front of the activated expression domain, we derive a range of analytical results. In particular, we observe the phase transition between patterns with expanding contact zone and patterns with contact zone of a well-defined size. Further, we provide exact conditions ensuring pattern stability. Finally, we classify two-gene regulatory motifs found in biological systems into classes resulting in different stability regimes.”

The seminar will be in a hybrid mode, local people are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on Tuesday, April 25 at 12:15, which will be given by

Marcus Niechciol (University of Siegen)

entitled

„Violations of Lorentz Invariance and Their Connections to Cosmic Particles“

Abstract:

“Lorentz invariance, i.e., the notion that the laws of physics should stay the same regardless of how an observer moves, is one of the pillars of modern physics. Yet, current efforts to construct a more fundamental theory beyond the standard model of particle physics open up a small window for violations of Lorentz invariance. Cosmic particles offer unique possibilities to search for such violations and thus test Lorentz invariance at energy scales far beyond the reach of man-made particle accelerators. Focussing on one specific theory framework, the talk will discuss how bounds on Lorentz violation within this framework have been obtained from measurements of cosmic particles by looking for processes that are forbidden in the conventional, Lorentz-invariant theory, but become allowed when Lorentz invariance is broken. In addition, a novel ansatz based on the extensive air showers initiated by cosmic particles in the Earth’s atmosphere will be presented. Using this approach, the bounds on Lorentz violation have been improved by several orders of magnitude.”

The seminar will be in a hybrid mode, local people are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on Tuesday, April 18 at 12:15, which will be given by

Wojciech Florkowski (IFT UJ)

entitled

" Spin hydrodynamics and pseudogauge transformations”

Abstract:

"Several recent approaches to relativistic hydrodynamics of particles with spin ½ will be shortly reviewed. A possible explanation of the (in)sensitivity of the obtained results to the so called pseudogauge transformation will be offered."

The seminar will be in a hybrid mode, local people are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on Tuesday, April 4 at 12:15, which will be given by

Piotr Korcyl (IFT UJ)

entitled

"Recent progress in Monte Carlo simulations enhanced with machine learning techniques”

Abstract:

"Several ways of incorporating machine learning techniques into Monte Carlo algorithms have been proposed in the last couple of years. After a brief introduction, I will summarize the progress of our group in this direction concentrating on the use of autoregressive neural networks in simulations of discrete statistical systems. I will also discuss future prospects of these methods in particle physics."

The seminar will be in a hybrid mode, local people are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on Tuesday, March 28 at 12:15, which will be given by

Paweł Sznajder (NCBJ)

entitled

"Machine learning techniques in phenomenology of generalised parton distributions (GPDs)”

Abstract:

"Generalised partons distributions (GPDs) describe the internal structure of hadrons in terms of quarks and gluons. They can be used, for instance, to study so-called nucleon tomography, and to access elements of the QCD energy-momentum tensor. Reconstruction of GPDs is a particularly difficult task, as available data are sparse compared to the number of objects and dimensions one must consider. In addition, one needs to solve a difficult inverse problem and fulfil a set of not trivial theory-driven constraints. In my talk I will show how elements of machine learning can be adapted and used for these purposes. I will focus on artificial neural networks, stressing their complementarity to classic techniques, like parametric fits. Technicalities involving e.g. genetic algorithms will also be described. "

The seminar will be in a hybrid mode, local people are invited to meet in the seminar room D-2-02.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz