# Widok zawartości stron

## Aktualności

# Blogi

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

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on Tuesday, March 21 at 12:15, which will be given by

Gergely Marko (University of Bielefeld)

entitled

"Electric susceptibility of the strongly interacting plasma"

Abstract:

"The response of strongly interacting matter to a background magnetic field is well understood by now thanks to first principles lattice QCD studies. The introduction of an electric field, however, suffers from a sign problem in Monte Carlo simulations, while also raising questions on the definiteness of a thermal equilibrium in general. As a first step towards lattice simulations for the electric susceptibility of QCD, we study the leading response of hot quark matter to external electric fields using a perturbative expansion in equilibrium thermal field theory. We discuss the specifics of the equilibrium state in the presence of the external electric field and calculate the susceptibility in a small field expansion. In comparison we also brush up the evaluation of the effective action in constant electric backgrounds using Schwinger's exact propagator obtained as one of the earliest results in the worldline formalism. We point out that the two approaches lead to different results, and discuss the origin of the difference."

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 14 at 12:15, which will be given by

Krzysztof Cichy (UAM)

entitled

"Probing nucleon's 3D structure with Lattice QCD"

Abstract:

"Large momentum effective theory relates lattice-calculable non-local correlations of boosted nucleon states to light-front partonic distributions. An example of such functions are generalized parton distributions (GPDs), which describe the spatial distributions of partons in the transverse plane. Until recently, a practical obstacle for computing GPDs was the need to perform separate calculations for every momentum transfer vector, required in the standard symmetric (Breit) frame of reference. Last year, we developed a new method based on parametrization of the relevant matrix elements in terms of Lorentz-invariant amplitudes. This allows one to extract GPDs in an efficient manner from asymmetric frames, by grouping calculations for several momentum transfers in a single lattice calculation. I will discuss the most recent progress in this field and discuss its further prospects."

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 7 at 12:15, which will be given by

Sándor Lökös (IFJ PAN)

entitled

"On the shape of the Bose-Einstein correlation function"

Abstract:

" Quantum statistical correlations were discovered by Hanbury Brown and Twiss by studying astrophysical objects in 1956. Later, the phenomena was also observed in high energy physics by Goldhaber, Goldhaber, Lee and Pais. The correlation function can be linked to the geometrical size of the source; that feature allowed astrophysicist to determine angular diameter of stars and it allows to perform investigation on the femtometer scale in high energy reactions. Hence the field usually refered as femtoscopy, however, the term was coined much later than the discovery. Precise measurements of the shape of such correlation functions revealed that the usually assumed Gaussian source shape is insufficient to describe the data and a more general source distribution should be considered, i.e., the Levy-stable distributions. The shape of the correlation functions is important not only because of its power of mapping the spatio-temporal structure of the emitting source on the femtometer scale but the detailed investigation could reveal underlying processes like partially coherent particle production, in-medium mass modifications or could give us information about the QCD phase diagram. In my presentation I will discuss the theoretical basis of the HBT analyses and give an exhaustive overview of recent experimental results from RHIC and LHC."

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, February 28 at 12:15, which will be given by

Nikodem Witkowski (IFT UJ)

entitled

"Coalescence model of deuteron production"

Abstract:

"Coalescence model describes production of light nuclei in hydro-inspired thermal model. After introducing the theory of thermal model and coalescence two approaches to the system symmetry were introduced. Within both regimes adequate model were developed and their predictions were compared to the experimental data. "

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, January 24 at 12:15, which will be given by

Piotr Kotko (AGH)

entitled

“Gluon scattering amplitudes within a new Wilson line-based action for gluodynamics”

I discuss a reformulation of the Yang-Mills action, that allows for an efficient calculation of gluon tree amplitudes. The new action is obtained via canonical field transformations that are based on Wilson line type functionals. I also discuss prospects and initial results for loop amplitudes.

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,

December 13 at 12:15, which will be given by

Yizhuang Liu (IFT UJ)

entitled

“Asymptotic KNO scaling for Mueller's dipole in the double-logarithm limit”

We analyze Mueller's QCD dipole wave function evolution in the double logarithm (DLA) limit. Using complex analytic methods, we show that the distribution of dipoles in the wave function asymptotically satisfies the Koba-Nielsen-Olesen (KNO) scaling with a novel scaling function f(z). The behavior of the scaling function in the DLA limit is qualitatively different from the expected scaling e^{-z} in the diffusion limit: at large z the f(z) decays as ze^{-z/0.3917} , while at small z the speed of growth is log-normal-like . The bulk and asymptotic results are shown to be in good agreement with the measured hadronic multiplicities in DIS, as reported by the H1 collaboration at HERA.

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,

December 6 at 12:15, which will be given by

Zdzisław Burda (AGH)

entitled

“Cleaning large-dimensional covariance matrices for correlated samples".

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,

November 29 at 12:15, which will be given by

Alberto Ramos (University of Valencia)

entitled

“Many uses of automatic differentiation".

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,

November 22 at 15:15, which will be given by

Farid Salazar (Institute for Theoretical Physics, UCLA)

entitled

“Sudakov suppression and gluon saturation at NLO".

The seminar will be ONLY in a remote mode.

Piotr Korcyl, Jacek Wosiek, Michał Praszałowicz

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on Tuesday,

November 15 at 12:15, which will be given by

Michał Praszałowicz (IFT UJ)

entitled

“Konferencja Excited QCD 2022".

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,

November 8 at 12:15, which will be given by

Pavel Buividovich (University of Liverpool)

entitled

“Quantum chaos in supersymmetric quantum mechanics".

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, October 25 at 12:15, which will be given by

Giorgio Torrieri (Campinas University)

entitled

“The hidden gauge symmetry of relativistic dissipative hydrodynamics “

Abstract: The observation, in hadronic collisions, of "ideal fluid" type behavior in systems of a comparatively small number of particles, presents a conceptual puzzle, since the way we usually derive hydrodynamics is via approximating "many" particles as a continuum. I will argue that making sense of this requires re-deriving relativistic hydrodynamics as a "bottom-up" theory, with no reference to microscopic physics except the local emergence of a thermalized system. We attempt to do this using basic statistical mechanics, and find the appearance of a gauge-like redundancy hidden within relativistic dissipative hydrodynamics, arising from the fluctuation-dissipation theorem. This might lead to the apparently counter-intuitive conclusion that in the small viscosity limit it might indeed be that smaller systems could thermalize faster.

The seminar will be on-site in the seminar room D-2-02.

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on MONDAY,

October 17 at 12:15, which will be given by

David Albandea (University of Valencia)

entitled

“Learning trivializing maps“

Abstract: The recent introduction of machine learning techniques, especially normalizing flows, for the sampling of lattice gauge theories has shed some hope on improving the sampling efficiency of the traditional HMC algorithm. However, naive usage of normalizing flows has been shown to lead to bad scaling with the volume. In this talk I will introduce normalizing flows commenting on its computational cost scaling towards the continuum. I will then propose using local normalizing flows at a scale given by the correlation length: even if naively these transformations have a very small acceptance, when combined with HMC lead to algorithms with high acceptance and reduced autocorrelation times compared with HMC.

The seminar will be in a hybrid mode, local people 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 11 at 12:15, which will be given by

Leszek Motyka and Tomasz Stebel (IFT)

entitled

"Diffraction / Low x 2022".

The seminar will be in a hybrid mode, local people 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 4 at 12:15, which will be given by

Kayman Jhosef Carvalho Gonçalves (Campinas University)

entitled

“Spin alignment of vector mesons as a probe of spin hydrodynamics and freeze-out“

Abstract: We argue that a detailed analysis of the spin alignment of vector mesons can serve as a probe of some aspects of spin dynamics in the vortical fluid for which there have been quite a few theoretical developments but relatively little phenomenology: The degree of relaxation between vorticity and parton spin polarization, and the degree of coherence of the hadron wavefunction at freeze-out. We show, using a coalescence model, that local spin density and vorticity impact the hadron wavefunction in different ways, and this is much more straightforward to disentangle for a vector meson than for a spin 1/2 baryon. We comment on the relevance of this issue for the current lack of consistency between experimental data on Lambda polarization and K*, phi spin alignment. Based on https://arxiv.org/abs/2104.12941

The seminar will be in a hybrid mode, local people 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,

June 14 at 12:15, which will be given by

Karol Życzkowski (IFT)

entitled

“Thirty-six quantum officers of Euler: quantum solution of a classically impossible problem”

Abstract: Negative solution to the famous problem of 36 officers of Euler implies that there are no two orthogonal Latin squares of order six. We show that the problem has a solution, provided the ranks and the units of each officer can be entangled, and construct quantum orthogonal Latin squares of this size. The solution can be visualized on a chessboard of size six, which shows that 36 officers are split in nine groups, each containing of four entangled states. This design provides a unique example of extremal quantum state and allows us to construct an original quantum error detection code.

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

We would like to invite you to the lecture on The physics of the QCD energy-momentum tensor

The lecture will be on Monday, 6th June at 2pm:

https://events.ncbj.gov.pl/event/137

Speaker: Cédric Lorcé (CPHT, École Polytechnique, Palaiseau, France)

Title: The physics of the QCD energy-momentum tensor (2/2)

Dear All,

we have the pleasure to invite you to the Particle Theory Seminar on Tuesday,

June 7 at 12:15, which will be given by

prof. Gert Aarts (Swansea University)

entitled

“Machine learning for lattice field theory and back”

Abstract: Recently, machine learning has become a popular tool to use in fundamental science, including lattice field theory. Here I will report on recent progress, starting with (by now) basic applications (phase transitions and critical exponents), moving on to new ideas for the Inverse Renormalisation Group and ending with more speculative suggestions on quantum-field theoretical machine learning.

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