SM&FT 2017 - The XVII Workshop on Statistical Mechanics and nonpertubative Field Theory

13 Dec 2017, 00:15 → 15 Dec 2017, 18:50 Europe/Rome

Centro Polifunzionale UniBA

Wednesday, 13 December

08:30 → 09:00 Registration

09:00 → 09:20 Welcome and Introduction

09:20 → 11:00 Session 1

Convener: Giovanni Cicuta (INFN)

09:20 Pathway-based analysis of gene expression data: method and applications.

I will first review a “systems approach” to analysis of high throughput large gene expression datasets. The basic idea, of using existing knowledge (assigning genes to biological pathways) to transform gene level information into “coarse-grained” system-level information, has been implemented in Pathifier [1] – an algorithm that infers pathway deregulation scores for each sample, on the basis of expression data. The algorithm generates a compact and biologically relevant representation of each sample, and as an added benefit, eliminates the “curse of dimensionality” and the need for uncontrolled feature selection, that have plagued standard single-gene based analysis. Pathifier has been used by us [1,2] and many other groups to study cancer [3] obesity [4] and other biomedical problems. In the second part of my talk I will review a few of these recent applications of the method. [1] Pathway-based personalized analysis of cancer. Yotam Drier, Michal Sheffer, and Eytan Domany, PNAS 110, 6388 (2013) [2] Pathway-based personalized analysis of breast cancer data. Anna Livshits et al, Molecular Oncology 9, 1471 (2015). [3] Personalised pathway analysis reveals association between DNA repair pathway dysregulation and chromosomal instability in sporadic breast cancer. Chao Liu et al Molecular Oncology 10, 179 (2016); Network analysis of EMT and MET micro-RNA regulation in breast cancer. Diana Drago-Garcia et al, Scientific Reports 7, 13534 (2017); Novel personalized pathway-based metabolomics models reveal key metabolic pathways for breast cancer diagnosis. Sijia Huang et al Genome Medicine 8, 34 (2016). [4] Integrative analysis of pathway deregulation in obesity. Francesc Font-Clos, Stefano Zapperi and Caterina La Porta, Systems Biology and Applications 3, 18 (2017).

Speaker: Prof. Eytan Domany (Weizmann Institute of Science)

Slides Domany.pdf

10:00 Abeta peptides and beta-sheet breakers. A coarse grained molecular dynamics approach

The problem of protein misfolding is of the utmost biological and medical interest, since it is at the basis of a class of pathologies known as protein conformational disorders or amyloidosis. These diseases are characterised by the mis-folding of proteins that, becoming insoluble, accumulate in aggregates of fibrillar shape. It is remarkable that all the known neuro-degenerative diseases belong to the class of amyloidosis pathologies. Among them, the Alzheimer Disease (AD) is one of the most studied for its enormous impact. The brain of AD patients is known to display accumulation of Abeta peptides amyloid plaques. The Abeta peptides originate from the proteolytic cleavage of a membrane protein called APP (Abeta Precursor Protein). The process that leads to the misfolding, aggregation and amyloid plaques formation is not yet fully elucidated. It seems, however, that the "starting point" of the process is an abnormal switch of the peptide secondary structure that leads to beta-sheet formation, a peculiar structure able to promote the formation of "stackable" sheets with intermolecular bonding. Unfortunately, nowadays, an effective treatment for AD is still missing. Several effectors have been studied in order to interfere with the Abeta aggregation process. Recently, the observation that short synthetic peptides, called beta-sheet breaker (BSB's), are able to directly interact with soluble oligomers or amyloid aggregates precluding amyloid polymerisation, was at the origin of a significant scientific effort aimed at trying to modulate and prevent Abeta aggregation and fibrillation processes. In this general framework and admittedly with the ultimate ambitious goal of providing structural information for the possible development of a really effective pharmaceutical strategy, it appears to be of the greatest bio-medical relevance to try to elucidate the way Abeta peptides interact with such compounds. In the work I am going to present here, we have studied the aggregation process of Abeta_1-40 peptides in the presence or in the absence of the BSB's with the help of Coarse Grained Classical Molecular Dynamic simulations. Our investigation shows that among the various BSBs proposed in the literature, the Ac-LPFFN-NH_2 peptide, designed and first studied by the Tor Vergata Biophysics group, is the most effective in reducing the Abeta_1-40 residues mobility and thus delaying fibril formation.

Speaker: Emiliano De Santis (ROMA2)

Slides EmilianoDeSantis_13-12-2017.pdf

10:20 Multi-scale molecular dynamics & first-principle calculations of X-ray absorption spectra: an application to the study of metal cation coordination in water

The progress in high performance computing we are witnessing today offers the possibility of accurate ab initio calculations of systems in realistic physico-chemical conditions. In this talk we present a parameter-free strategy aimed at performing a first-principle computation of the low energy part of the X-ray Absorption Spectroscopy (XAS) spectrum based on density functional theory (DFT). As a first application we apply this strategy to determine the coordination mode of Cu(II) and Zn(II) in water. The necessary model system configurations are built starting from classical molecular dynamics (MD) and tight-binding calculations on metal-water complexes. Then, DFT is exploited to relax the resulting metal-water geometrical structures. Finally the XAS spectra associated to the resulting structures are calculated. The comparison with experimental data shows that the Zn(II) spectral features are nicely reproduced from structures with an octahedral Zn(II) coordination, while the Cu(II) spectrum can be properly reproduced assuming a weighted combination of penta- and hexa-coordinated Cu(II). The success of the approach in these two paradigmatic cases makes us optimistic about the possibility of extending our strategy to the calculation of XAS spectra of Cu(II) and Zn(II) ions in the more interesting - and much more computationally demanding - case in which they are in complex with molecules of biological relevance, such as, for example, the amyloid beta peptide involved in the pathogenesis of Alzheimer’s disease.

Speaker: Francesco Stellato (ROMA2)

Slides Stellato_Bari_13Dec17.pdf

10:40 Large Deviations in Renewal Models of Statistical Mechanics

Cramér's theorem provides a large deviation principle for the empirical mean of independent and identically distributed random variables. In this talk I establish a generalization of Cramér's theorem for renewal-reward processes associated with a constrained renewal process where one of the renewals occurs at a predetermined time. With a different interpretation of the time coordinate, this constrained renewal process includes important models of statistical mechanics such as the pinning model of polymers, the Poland-Scheraga model of DNA denaturation, the Wako-Saitô-Muñoz-Eaton model of protein folding, and the Tokar-Dreyssé model of strained epitaxy.

Speaker: Dr Marco Zamparo (Politecnico di Torino)

Slides Zamparo_Presentation.pdf

11:00 → 11:30 Coffee

11:30 → 13:00 Session 2

Convener: Michele Caselle (TO)

11:30 Anomalous dimensions without Feynman diagrams from Conformal symmetry of Wilson-Fisher fixed points

We compute, to the first non-trivial order in the epsilon expansion, the anomalous dimensions of an infinite class of local operators, including the partially conserved higher spin currents, using only constraints from conformal symmetry. According to the bootstrap philosophy, no reference is made to any Lagrangian, equations of motion or coupling constants.

Speaker: Ferdinando Gliozzi (Torino University)

Slides bari2017.pdf

12:00 Plastic flow and stochastic resonance in soft glassy materials

Flow in soft-glasses occurs via a sequence of reversible elastic deformations and local irreversible plastic rearrangements. Yield events in the material cause kicks adding up to an effective thermal noise, an intuition that has inspired the development of phenomenological models aiming at explaining the main features of soft-glassy rheology. We provide a specific scenario for such mechanical activation, based on a general paradigm of non-equilibrium statistical mechanics, namely stochastic resonance. By using mesoscopic simulations of dense emulsions subject to an oscillatory strain, we characterize the response of the system and highlight a resonance-like behaviour in the plastic rearrangements. This confirms that the synchronization of the system response to an external time-dependent load is triggered by the mechanical noise resulting from intrinsic structural disorder, quantified by the polydispersity.

Speaker: Dr Andrea Scagliarini (IAC-CNR)

Slides Scagliarini_SMFT2017.pdf

12:20 Exact results for quenched disorder at criticality

We show how an exact field theoretical replica method can be formulated for the study of two-dimensional systems with quenched disorder at criticality. For the q-state Potts model we obtain a solution which appears to solve longstanding theoretical and numerical puzzles about the disordered ferromagnet. The space of solutions with Potts permutational symmetry also accounts for strong disorder critical points such as the Nishimori point. All these solutions are found to exhibit superuniversal (i.e. symmetry independent) sectors. References: [1] G. Delfino, Exact results for quenched bond randomness at criticality, PRL 118 (2017) 250601. [2] G. Delfino and E. Tartaglia, On superuniversality in the q-state Potts model with quenched disorder, arXiv:1709.00364, to appear in JSTAT.

Speaker: Gesualdo Delfino (TS)

Slides Delfino_Bari17.pdf

12:40 Strong interaction in background magnetic fields

I will present some recent results obtained in our on-going effort devoted to the study of the influence of strong external magnetic fields on the heavy quark-antiquark interaction. These fields, expected to be created in physical situations such as heavy-ion collisions, may induce relevant modifications of the properties of the strong force. In particular, in this talk I will focus both on the effects on the static potential in the confined regime and on the screening masses in the deconfined region at very high temperatures, showing how and in which extent these observables are affected.

Speaker: Andrea Rucci (University of Pisa and INFN Pisa)

Slides presentation.pdf

13:00 → 14:30 Lunch

14:30 → 16:30 Session 3

Convener: Giuseppe Gonnella (BA)

14:30 Designing effective anticancer-radiopeptide carriers A Molecular Dynamics study of their interaction with model tumor and healthy cell membranes

We present in this talk an extensive Molecular Dynamics study of the interaction between a newly designed anticancer-radiopeptide and (models of) tumor and healthy cell membranes. Inspired by the mechanism by which antimicrobial peptides interact with the negatively charged bacterial membranes, we have modified the human antimicrobial peptide LL-37 to get a functionalized radionuclide carrier capable of binding to the negatively charged tumor membranes but not to the neutral healthy ones. This selectivity property results from the fact that at the slight acidic pH surrounding tumor tissues the histidines belonging to the peptide get protonated thus making it positively charged. Computation of the binding free-energy between the peptide and different kinds of membranes confirms that the affinity of the peptide to tumor membranes is significantly larger than to healthy tissues. These features (high affinity and generic tumor selectivity) recommend antimicrobial derived customized carriers as promising theranostic constructs in cancer diagnostic and therapy.

Speaker: Velia Minicozzi (ROMA2)

Slides Minicozzi_SM&FT2017.pdf Minicozzi_SM&FT2017.pptx

14:50 Yield Transition and Controlled Fluidization of Soft-Glassy Materials

Emulsions are soft-glassy materials made of non-coalescing droplets moving in a continuous component. Above the jamming point, they display unique properties that endow them with both solid and plastic features: when an external forcing is applied the system responds as an elastic solid until a threshold is overcome, the so-called yield stress, above which the system flows through a series of irreversible plastic events occurring as a sequence of topological changes in the droplets distribution. Emulsions stand as extremely interesting systems both from the technological (pharmaceutical and oil industry...) and the theoretical (out-of-equilibrium statistical mechanics) points of view. Leveraging the computational power of GPUs we developed a general tool for the prompt detection of plastic events and the tracking of droplets in Lattice Boltzmann model emulsions which allowed us to study with an unprecedented statistics micro-channel flows, crucial in technical applications, as well as emulsions microscopic dynamics at the onset of the yield-stress transition. In this talk we will briefly introduce the computational technique and show the results obtained in the control of the emulsion fluidization by means of rough micro-channels as well as the most recent ones regarding the onset of the yield-stress where we observed a reversible tunneling from the solid to the liquid phases along with long-ranged correlations. The author acknowledges the project “High performance data network: Convergenza di metodologie e integrazione di infrastrutture per il calcolo High Performance (HPC) e High Throughput (HTC)” (fondi CIPE) for support. [Computer Physics Communications, 2017, 213, 19 – 28; Physical Review E, 2017, 95, 052602; arXiv:1710.00686 [cond-mat.soft]]

Speaker: Matteo Lulli (ROMA2)

Slides slidesMatteoLulli.pdf

15:10 Entanglement measures in Extended Quantum Systems: The Negativity Spectrum

In recent years the irruption in other research fields of concepts and methods coming from Quantum Information Theory turned out to be very fruitful. So far, particular attention has been devoted to the characterization of different measures of entanglement [1, 2] in physical states of extended systems such as quantum field theories (QFT) and more generally speaking many-body quantum matter. In this talk, I will review the QFT approach to entanglement measures [3] and then concentrate to the case of conformal field theories in (1+1) dimensions. Among the entanglement measures, I will introduce a new measure, that we dubbed "negativity spectrum" [4], being a sort of the analogous of the entanglement spectrum for the case of mixed states of quantum systems. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ References: [1] M. B. Plenio and S. Virmani, An introduction to entanglement measures, Quant. Inf. Comput. 7, 1 (2007). [2] L. Amico, R. Fazio, A. Osterloh, and V. Vedral, Entanglement in many-body systems, Rev. Mod. Phys. 80, 517 (2008). [3] P. Calabrese, J. Cardy, and B. Doyon Eds, Entanglement entropy in extended quantum systems, J. Phys. A 42 500301 (2009). [4] P. Ruggiero, V. Alba, P. Calabrese, Negativity spectrum of one-dimensional conformal field theories, Phys. Rev. B 94, 195121 (2016) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Speaker: Paola Ruggiero (T)

Slides Negativity-spectrum.pdf

15:30 Chaotic dynamical phase induced by non-equilibrium quantum fluctuations

In recent years, the dynamical consequences of spontaneous symmetry breaking have been investigated: What is the fate of the order parameter when the system is driven away from equilibrium? Mean-field analyses suggest that dynamical criticality sistematically appears. However, they rigorously describe unrealistic infinite-range of infinite-dimensional limits, where few collective macroscopic variables play a role and all the microscopic degrees of freedom, associated with spatial fluctuations, are frozen. It is a matter of principle to understand whether such dynamical criticality is robust to the inclusion of fluctuations (that are present even at zero temperature in quantum systems): will they be able to drive the system to thermal equilibrium, and hence trivialize the dynamical critical phenomenon into a standard equilibrium transition? If so, the above dynamical criticality would just be a mean-field artifact. We address this problem by studying an infinite-range Ising model in a transverse field with an additional short-range interaction. I will show a viable systematic approach to deal with the out-of-equilibrium dynamics that goes beyond mean-field. The results are rather surprising: the spatial fluctuation modes turn out to have a deep impact to the dynamical critical point, giving rise to a whole new region with chaotic features, characterized by an "unpredictable" asymptotic order for long times. The latter non-trivial phenomenon, confirmed by numerical simulations of the exact quantum dynamics, is completely absent at mean-field level.

Speaker: Alessio Lerose (TS)

Slides Bari13-12-17_AlessioLerose.pdf

15:50 Corner contributions to holographic entanglement entropy in AdS4/BCFT3

Entanglement entropy of a subsystem is a quantity of great interest in statistical physics, condensed matter and high energy physics. In conformal field theories (CFTs) that admit a gravitational dual description via the AdS/CFT correspondence, the entanglement entropy can be studied by computing the area of the minimal surfaces anchored to the boundary of the subsystem. While much work has been done for holographic CFTs without boundaries, there is still much to understand in the correspondence for holographic CFTs with a boundary (AdS/BCFT correspondence). In this talk I will consider the holographic entanglement entropy of some spatial regions in the AdS4/BCFT3 correspondence. When the region contains corners whose vertex is on the boundary, a universal logarithmic divergent contribution occurs in the holographic entanglement entropy whose coefficient (corner function) encodes the boundary conditions of the underlying BCFT. Analytic expressions for the simplest corner functions are presented. A relation with the one point function of the stress tensor is discussed. A detailed numerical analysis has been performed to check the analytic results by computing the area of the minimal surfaces corresponding to finite domains.

Speaker: Jacopo Sisti (TS)

Slides Corner_contribution_to_enganglement_entropy_in_AdSBCFT3.pdf

16:10 Thermal fluctuations of an interface near a contact line

The effect of thermal fluctuations near a contact line of a liquid interface partially wetting an impenetrable substrate is studied analytically and numerically. Promoting both the interface profile and the contact line position to random variables, we explore the equilibrium properties of the corresponding fluctuating contact line problem based on an interfacial Hamiltonian involving a “contact” binding potential. To facilitate an analytical treatment, we consider the case of a one-dimensional interface. The effective boundary condition at the contact line is determined by a dimensionless parameter that encodes the relative importance of thermal energy and substrate energy at the microscopic scale. We find that this parameter controls the transition from a partial wetting to a pseudopartial wetting state, the latter being characterized by a thin prewetting film of fixed thickness. In the partial wetting regime, instead, the profile typically approaches the substrate via an exponentially thinning prewetting film. We show that, independently of the physics at the microscopic scale, Young’s angle is recovered sufficiently far from the substrate. The fluctuations of the interface and of the contact line give rise to an effective disjoining pressure, exponentially decreasing with height. Fluctuations therefore provide a regularization of the singular contact forces occurring in the corresponding deterministic problem.

Speaker: Daniele Belardinelli (ROMA2)

Slides slide_CL.pdf

16:30 → 17:00 Coffee

17:00 → 19:00 Session 4

Convener: Michele Pepe (MIB)

17:00 Exact solution of the Polyakov loop models in the large-N limit

A dual formulation of U(N) and SU(N) Polyakov loop models is constructed for all N and in any number of dimensions. The construction is based on the theory of the Weingarten functions. In the case of a complex external field a sufficient condition for the dual Boltzmann weight to be positive is derived. As an application of the dual formulation we report on the exact solution of U(N) models in the large-N limit. Also, we calculate the first correction to the large-N limit for SU(N) models.

Speaker: Oleg Borisenko (Bogolyubov Institute for Theoretical Physics, Academy of Sciences of Ukraine)

Slides borisenko.pdf

17:20 Non-perturbative Renormalization and Running of quark masses in $N_f=3$ QCD

I present our results for the computation of the non-perturbative renormalization and running of the renormalized quark masses in $N_f = 3$ QCD. Adopting finite-size scaling techniques, the running is computed from low energy scales $\sim \Lambda_{\rm QCD}$ to high energy $\sim M_W$. This large range of scales allows to make contact from one side with a "hadronic" renormalization scheme, and on the other with perturbation theory. The computation is carried out to very high precision, using massless $\mathcal{O}(a)$ improved Wilson quarks.

Speaker: David Preti (INFN sezione di Torino)

Slides Talk_PretiDavid.pdf

17:40 Testing a non-perturbative mechanism for elementary fermion mass generation

Based on a recent proposal according to which elementary particle masses could be generated by a non-perturbative dynamical phenomenon, alternative to the Higgs mechanism we carry out lattice simulations of a model where a SU(2) fermion doublet, subjected to non-Abelian gauge interactions, is also coupled to a complex scalar field doublet via a Yukawa and an "irrelevant" Wilson-like term. We present preliminary numerical results using naive fermions in quenched approximation both in the Wigner and in the Nambu-Goldstone phase of the model, focusing on the observables relevant to check the occurrence of the conjectured dynamical fermion mass generation effect in the continuum limit of the critical theory in its spontaneously broken phase.

Speaker: Marco Garofalo (ROMA2)

Slides sm_and_ft_2017_Garofalo.pdf

18:00 Morphology and flow patterns in active emulsions

Active Matter has estabilished itself as a topical area in Statistical Mechanics over the last decade. Active fluid systems, in particular, are internally driven and continuosly supply energy in their surroundings. Here I present a numerical study about morphology and flow patterns in a binary mixture of a passive isotropic fluid and an active polar gel, conducted through the implementation of a LBM algorithm. The choice of parameters in the underlying free energy of our mean-field model favours the lamellar phase in the passive limit, while it leads to a range of multifarious exotic emulsions, depending both on the importance of active doping and overall concentration of the two components. If the mixture is symmetric and the active component is contractile (e.g. an actomyosin solution), moderate activity enhances the efficiency of lamellar ordering, whereas strong activity leads to an emulsion of passive droplets within an active matrix. In a higly off-symmetric mixture with extensile minority component (e.g. microtubule bundles gel in an oil background), in the moderate active-doping regime, a hexatic array of active droplets is formed with some defects in the arrangement, while for stronger doping, a suspension of aster-like rotating domains emerges. We find that mean kinetic energy and enstrophy can be used to mark the transition from the ordered to the disordered regime, regardless of the overall mixture composition. Furthermore a comparison between relevant lengthscales of the structure factors of both active forces and velocity fields offers a first clue to pave the road towards a more complete characterization of active turbulence.

Speaker: Mr Livio Nicola Carenza (Università degli Studi di Bari)

Slides Presentazione_Carenza.pdf

Thursday, 14 December

09:00 → 11:00 Session 5

Convener: Alessandro Papa (CS)

09:00 Strong interacting models for BSM: a lattice approach

Several models of strong dynamics beyond the Standard Model have been recently studied by formulating the strong theory on a discretised spacetime. Monte Carlo simulations can provide nonperturbative results from a first principle approach, and shed light on models like walking technicolor, and composite Higgs. I will summarise recent progress, and identify the limitations and the potential for future studies in this field.

Speaker: Dr Luigi Del Debbio (University of Edinburgh)

Slides Bari17.pdf

09:40 Probing renormalized perturbation theory with data from lattice QCD at high energies

Using lattice QCD and a finite space time volume to set the scale, a family of renormalized QCD couplings in SF schemes can be traced non-perturbatively from intermediate to high energies of O(100 GeV), where perturbation theory is expected to work very well. I will first discuss the continuum extrapolation of the lattice data and then assess the quality of renormalized perturbation theory in a number of ways, based on the available 2-loop matching between the MSbar and the SF schemes.

Speaker: Dr Stefan Sint (Trinity College Dublin)

Slides bari17.pdf

10:20 QCD phase diagram

I will review recent progress in determining the QCD phase diagram from ab initio lattice QCD calculations. In particular, I discuss results on fluctuations and higher-order cumulants at non-zero baryon density, constraints on the location of the critical point, the freeze-out line and the QCD equation of state at finite density.

Speaker: Prof. Bazavov Alexei (Michigan State University)

Slides bazavov_smft2017.pdf

11:00 → 11:30 Coffee

11:30 → 13:10 Session 6

Convener: Leonardo Angelini (BA)

11:30 QCD monopoles, Abelian Projections and Gauge Invariance

Condensation of monopoles in Non Abelian Gauge Theories is shown to be a gauge-invariant property and Abelian projection independent. The order parameter is computed numerically for $SU(2)$ and $SU(3)$ theories: it is consistent with dual superconductivity of the confining vacuum.

Speaker: Adriano Di Giacomo (PI)

Slides BBdigiacomo_Bari.pdf

11:50 Confinement and the Coulomb gauge

The Gribov-Zwanziger confinement mechanism has enjoyed increased attention in the last few years. Although it can be both formulated in covariant and Coulomb gauge, the latter version allows to investigate the properties of the QCD vacuum wave functional in the continuum and can be linked to well defined lattice quantities. In this talk I will review the relevant Coulomb gauge results on the lattice and in the continuum and address open issues and problems inherent to the technique.

Speaker: Dr Giuseppe Burgio (Universität Tübingen)

Slides bari_burgio.pdf

12:10 Investigating the dynamics of biopolymers using field theory and path integrals

Biopolymers (such as proteins or nucleid acids) are prototypical examples of complex open systems. Indeed, in these systems, the interplay between strong correlations and large thermal fluctuations gives raise to non-perturbative phenomena such as frustration, meta-stability and cooperativity which are typical of complex systems. Large scale computer simulations of their classical structural dynamics and their quantum electronic structure could in principle provide a poweful and theoretically sound framework for theoretical investigations. Unfortunately, these methods are limited by their intrinsic complexity of the systems and by the co-existence of multiple widely separated time-scales. As a result, a gap of many orders of magnitude exists beteween the time scales which can be presently simulated by molecular dynamics and those which are relevant for biological applications. In this talk I will show how theoretical physics techniques originally developed in the context of high-energy and nuclear physics such as path integrals and renormalization group can be used to develop computational approaches which enable to perform simulations which are inaccessible to standard molecular dynamics. In particular, I will discuss an approach which enables to investigate in a unified manner both biologically relevant conformational transitions (such as protein folding) and the transport and decoherence of optically excited electronic excitations.

Speaker: Pietro Faccioli (TIFP)

Slides SM&FT17.pdf

12:30 Testing new Monte Carlo evolution algorithms in Grid

I will present the preliminary tests on two modifications of the Hybrid Monte Carlo (HMC) algorithm. Both algorithms are designed to travel much farther in the Hamiltonian phase space for each trajectory and reduce the autocorrelations among physical observables thus tackling the critical slowing down towards the continuum limit. We present a comparison of costs of the new algorithms with the standard HMC evolution for pure gauge fields, studying the autocorrelation times for various quantities including the topological charge. Both algorithms were implemented using the next generation Grid Data Parallel code developed by the University of Edinburgh and designed to achieve optimal performance on a wide range of architectures. I will discuss some of Grid features.

Speaker: Dr Guido Cossu (University of Edinburgh)

Slides GRID_HMC_Algorithms.pdf

12:50 The equation of state with non-equilibrium methods

Jarzynski's equality provides an elegant and powerful tool to compute directly ratios of partition functions in Monte Carlo simulations and it can be easily extended to lattice gauge theories in order to compute several physically interesting quantities. In this talk we present a novel technique to compute the equation of state of strongly-interacting theories based on this relation, which allows for a direct and efficient determination of the pressure using out-of-equilibrium Monte Carlo simulations on the lattice. We present recent results obtained with this method for the thermodynamics of the SU(3) Yang-Mills theory in the confined and deconfined phases.

Speaker: Mr Alessandro Nada (DESY Zeuthen)

Slides Nada.pdf

13:10 → 14:30 Lunch

14:30 → 16:30 Session 7

Convener: Sebastiano Stramaglia (BA)

14:30 Modeling gravitational-waves from binary neutron stars

The era of multi-messenger astronomy has started with the first observation of gravitational and electromagnetic radiation from a likely binary neutron star inspiral event. A single event delivered information about the unknown equation of state of matter at supranuclear densities, about the connection between mergers and short-gamma ray burst, about the site of production (via r-process nucleosynthesis) of heavy elements in the Universe, and about cosmography (independent measure of the Hublle constant). A crucial and necessary ingredient for LIGO and Virgo observations is the precise knowledge of the dynamics of the sources and of the emitted waveforms. I will talk about recent developments on the modeling of gravitational waves from neutron star mergers that use numerical simulations in general relativity.

Speaker: Sebastiano Bernuzzi (PR)

Slides Bernuzzi_SM&FT.pdf

15:10 Transient spiral arms and galaxy rotation curves

We describe how a simple class of out of equilibrium, rotating and asymmetrical mass distributions evolve under their self-gravity to produce a quasi-planar spiral structure surrounding a virialized core, qualitatively resembling a spiral galaxy. The spiral structure is transient, but can survive tens of dynamical times, and further reproduces qualitatively noted features of spiral galaxies as the predominance of trailing two-armed spirals and large pitch angles. As our models are highly idealized, a detailed comparison with observations is not appropriate, but generic features of the velocity distributions can be identified to be potential observational signatures of such a mechanism. Indeed, the mechanism leads generically to a characteristic transition from predominantly rotational motion, in a region outside the core, to radial ballistic motion in the outermost parts. Such radial motions are excluded in our Galaxy up to 15 kpc, but could be detected at larger scales in the future by GAIA. We explore the apparent motions seen by external observers of the velocity distributions of our toy galaxies, and find that it is difficult to distinguish them from those of a rotating disc with sub-dominant radial motions at levels typically inferred from observations. These simple models illustrate the possibility that the observed apparent motions of spiral galaxies might be explained by non-trivial non-stationary mass and velocity distributions without invoking a dark matter halo or modification of Newtonian gravity. In this scenario the observed phenomenological relation between the centripetal and gravitational acceleration of the visible baryonic mass could have a simple explanation.

Speaker: Dr francesco sylos labini (centro e. fermi)

Slides FSL_Bari_141207.pdf

15:30 The curvature of the chiral pseudocritical line from lattice QCD

The $T-\mu$ phase diagram of QCD is still largely unknown. However, by means of lattice QCD simulations, it is possible to reliably study the region close to the $\mu=0$ axis and in particular the behaviour of the chiral transition in this regime. I will present our determination of the curvature of the chiral pseudocritical line from $N_f=2+1$ lattice QCD at the physical point. I will mainly focus on the results obtained by the analytic continuation method, but I will also compare with the Taylor expansion method.

Speaker: Francesco Negro (PI)

Slides Negro_smft2017.pdf

15:50 The QCD chiral phase transition from non-integer numbers of flavors

Attempts to extract the order of the chiral transition of QCD at zero chemical potential, with two dynamical flavors of massless quarks, from simulations with progressively decreasing pion mass have remained inconclusive because of their increasing numerical cost. In an alternative approach to this problem, we consider the path integral as a function of continuous number $N_f$ of degenerate quarks. If the transition in the chiral limit is first-order for $N_f \ge 3$, a second-order transition for $N_f = 2$ then requires a tricritical point in between. This in turn implies tricritical scaling of the critical boundary line between the first-order and crossover regions as the chiral limit is approached. Non-integer numbers of fermion flavors are easily implemented within the staggered fermion discretization. Exploratory simulations at $\mu = 0$ and $N_f = 2.8, 2.6, 2.4, 2.2, 2.1$, on coarse $N_\tau = 4$ lattices, indeed show a smooth variation of the critical mass mapping out a critical line in the $(m,N_f)$-plane. For the smallest masses the line appears consistent with tricritical scaling, allowing for an extrapolation to the chiral limit.

Speaker: Dr Francesca Cuteri (Goethe Universität - Frankfurt am Main)

Slides talkSM&FT2017Cuteri.pdf (Protected)

16:10 Complex Langevin simulations of a finite density matrix model for QCD

We study the Stephanov model, which is a Random Matrix Theory model for QCD at finite baryon density, using the Complex Langevin algorithm. Naive implementation of the algorithm shows convergence towards the phase quenched or quenched theory rather than to the intended theory with dynamical quarks. A detailed analysis of this issue and various potential resolutions of the failure of this algorithm are discussed.

Speaker: Dr Savvas Zafeiropoulos (Universität Heidelberg)

Slides zafeiropoulos_Bari2017.pdf

16:30 → 17:00 Coffee

17:00 → 19:40 Session 8

Convener: Michele Pepe (MIB)

17:00 A portable LQCD Monte Carlo code using MPI and OpenACC

HPC systems used by scientific communities often include different kind of accelerators, such as GPUs. Accelerators can deliver an higher level of performance for HPC workloads than ordinary CPUs, but in general they require to rewrite applications using specific programming frameworks. For example, many HPC clusters nowadays are based on NVIDIA GPUs requiring to use the CUDA framework, which limits to run applications only on a subset of the possible HPC resources. To avoid this limitation, multiple code versions targeting different architectures could be developed, but this requires a significant programming effort, in particular for scientific applications where code changes are very frequent. To have a single portable code, another approach could be to use the OpenACC parallel programming model. In this case, the original source code is annotated with specific directives to instruct the compiler about how to map instructions on different processors. In this work, we present the implementation of a state-of-the-art production-level LQCD Monte Carlo application, written using OpenACC and MPI to manage multi-device parallelism. In particular, we give a short introduction to the OpenACC programming model, and we present the design and optimization strategies we have adopted for our code, together with performance results measured on modern HPC clusters based both on CPUs and GPUs.

Speaker: Enrico Calore (FE)

Slides calore-SMFT17.pdf

17:20 Quantitative machine learning study of the critical 2D Ising model

In the last few years, machine learning techniques have been applied to a large variety of classification problems. In this talk, we present a quantitative study of the critical behavior of an exactly solved model, the 2D Ising model, performed using a quadratic kernel Support Vector Machine. Under very mild assumptions, the critical exponents and the critical temperature are obtained with a precision comparable to that of reweighting methods.

Speaker: Dr davide vadacchino (INFN Sezione di Pisa)

Slides vadacchino.pdf

17:40 Charm and beauty: Heavy quark physics from lattice QCD

This is an excellent time to study heavy mesons that contain c and/or b quarks, as they are produced in abundance by B-factories and at LHCb. There are persistent discrepancies with Standard Model in the b to c semileptonic observables, for example the few-sigma anomalies in the so called R-ratios R(D), R(D*) and R(J/psi) recently announced by LHCb. Reliable Standard Model predictions of these quantities are thus needed to be compared to experimental measurements. Lattice QCD allows us to do a fully nonperturbative QCD calculation and study mesons and their semileptonic decays, providing high precision Standard Model predictions. In this talk I will focus on recent progress made by HPQCD Collaboration in determining the form factors related to these decays and the impact for phenomenology at LHCb and B-factories.

Speaker: Dr Jonna Koponen (INFN sezione di Roma Tor Vergata)

Slides Bari_workshop_JonnaKoponen.pdf

18:00 Investigation of the topological properties of the CP^(N-1) model

We measured the theta-dependence of the vacuum energy density of the CP^(N-1) model up to O(theta^6) for N = 15, 21, 26 and 31 using Monte Carlo simulations. We then extrapolated the large-N limit of the topological susceptibility chi and of the higher-order coefficients b_2 and b_4 and compared it with the analytic results. In particular, we compared the leading term of the 1/N expansion of these observables and, for the topological susceptibility, the next-to-leading-order term too.

Speaker: Claudio Bonanno (University of Pisa and INFN - Pisa section)

Slides slides_SM&FT_2017_Bonanno_Claudio.pdf

18:20 Spectral methods in Causal Dynamical Triangulations

Causal Dynamical Triangulations is one of the present promising numerical approaches to the problem of Quantum Gravity. Motivated by the current lack of observables encoding geometric features at all scales, I will present a new set of observables based upon the analysis of eigenvalues and eigenvectors of the Laplace-Beltrami operator of triangulations, and discuss the main results obtained with this method.

Speaker: Giuseppe Clemente (PI)

Slides cleme_SMFT_14-12-17.pdf

18:40 The effect of ‘contrarians’ on the emergence of collective intelligence in human groups

A large number of numerical models have been proposed by researchers in order to investigate the effect of contrarian on opinion formation in groups. In this work we extend the Decision-Making Model (DMM), previously developed by the same authors, to show that under specific conditions the presence of ‘contrarians’, i.e. of anti-consensus social interactions, may increase the efficacy of human groups in solving complex tasks. We investigate how the fraction of anti-consensus interactions moderates the effect of the strength of social consensus-interactions and the level of self-confidence on the long-term response of the decision process in terms of fitness values (V∞), thus providing a clear indication of the influence of ‘contrarians’ in determining the emergence of collective intelligence in groups.

Speaker: Mr Giovanni Francesco Massari (Politecnico di Bari)

Slides INFN_Pdf.pdf

20:30 → 22:30 Dinner

Friday, 15 December

09:00 → 11:00 Session 9

Convener: Raffaele Tripiccione (FE)

09:00 Large scale simulations of spin glasses

In this talk I would like to present some large scale simulations of spin glasses that have been obtained using the Janus-II computer. The correlations functions and the response functions has been measured for more that ten order of magnitudo. The largest times of the simulation correspond to a time scale (a tenth of second) that is not far from the experimental one.

Speaker: Giorgio Parisi (ROMA1)

Slides Bari2017Fin.pdf

09:40 Lattice overview and prospects in flavour physics

A review of lattice results for flavour phenomenology in the Standard Model and beyond is presented. In particular open problems and new quantities which could be computed in lattice QCD will be discussed together with present experimental hints of new physics from lepton universality violation.

Speaker: Guido Martinelli (ROMA1)

Slides MARTINELLI_Bari2017.ppt

10:20 Out-of-equilibrium physics in spontaneous synchronization

Spontaneous synchronization is a cooperative phenomenon common in nature which makes oscillators of different frequencies, if strongly coupled, operate together with a single common frequency. Such cooperative effects occur in physical and biological systems over length and time scales of several orders of magnitude. Examples are: flashing of fireflies, rhythmic applause in a concert hall, animal flocking behavior, electrical power-grids, etc. The most celebrated model of synchronization is the Kuramoto model, introduced in 1975, which is simple enough to allow quite a detailed analytical treatment, at the same time capturing several features of realistic systems. After discussing the general dynamical and statistical features of synchronization, I will present its out-of-equilibrium physical aspects when uncorrelated Langevin noise is added to the model.

Speaker: Stefano Ruffo (FI)

Slides RUFFO_SMFT_Bari_2017.pdf

11:00 → 11:30 Coffee

11:30 → 12:50 Session 10

Convener: Leonardo Cosmai (BA)

11:30 The BioPhys scientific activity

Experiments are devised to answer theoretical questions and theory is a necessary prerequisite to analyze data and extract useful information. The complexity of biological systems makes extremely difficult to construct models and identify simple questions to ask to experiments. On the other end, models in many cases look overwhelming complicated. In this situation Molecular Dynamics simulation, from ab initio to classical all atoms or coarse grained calculations, may provide foundation for theory and models that cannot only help in asking the right questions but also to assess and interpret experimental data. I will briefly illustrate some of the many interesting results that are being obtained by the research groups participating to the BioPhys IS.

Speaker: Silvia Morante (ROMA2)

Slides MORANTE_BioPhys.pdf

11:50 High Performance Computing: a tool for the study of turbulence

In this talk I will briefly review the use of HPC for different fundamental problems in the study of fully developed turbulence. Recent results on the signature of time irreversibility in the statistics of turbulent flows, and the role played by numerical simulations in these investigations, will be discussed in details.

Speaker: Guido Boffetta (TO)

Slides boffetta-fieldturb.pdf

12:10 The Euclid Mission

The European Space Agency's Euclid Mission will be launched in 2021. During its six-year mission, the Euclid satellite will survey nearly 40% of the sky, providing scientists with an extraordinarily large amount of data that will impact many aspects of modern cosmology and astrophysics. The Euclid Mission's primary science goals are targeted towards constraining the nature of two of the most puzzling quantities in our Universe: Dark Energy and Dark Matter. In order to do so, the Euclid Satellite will image billions of galaxies as well as measure tens of millions of spectra. In this talk we will summarize the main scientific objectives of the mission, focusing in particular to the topics closest to the INFN research interest, and the computational challenges emerging in the analysis of Euclid data.

Speaker: Alessandro Renzi (PD)

Slides Euclid_Bari_20171215_Renzi.pdf

12:30 The SFT scientific activity

I will briefly discuss the main research topics of the INFN research initiative SFT (Statistical Field Theory) with a particular attention to those involving HPC (mainly related to Lattice QCD)

Speaker: Michele Caselle (TO)

Slides Bari_SFT.pdf

12:50 → 14:20 Lunch

14:20 → 16:20 Session 11

Convener: Massimo D'Elia (PI)

14:20 NEUMATT: Numerical simulation of Binary Neutron Stars, Equation of State effects on the gravitational wave signal.

Binary Neutron Star systems are the most interesting source of gravitational wave signals and the associate signal will carry important information about the equation of state (EOS) of matter at high density. The main information on the EOS will be seen on the postmerger signal. (Not detected in the case for GW170817) In this talks I will discuss the various steps that one need to perform, starting from the EOS of matter at high density, to obtained the properties of the Gravitational Wave signal emitted during the merger and especially on the post-merger.

Speaker: Roberto De Pietri (PR)

Slides 2017_Bari.pdf

14:40 MANYBODY: Theory of nuclear quantum many-body systems

It is fascinating that the entire nuclear chart can be in principle described by the small set of parameters defining the quantum chromodynamics (QCD) and quantum electrodynamics Lagrangians. The direct applicability of Lattice-QCD, the only non-perturbative method that systematically implements QCD from first principles, is currently limited to very light nuclear systems. We present a novel framework that combines nuclear effective field theories, and ab-initio nuclear many-body methods to understand how the wealth of data and peculiarities on nuclei and hypernuclei emerge from QCD. On the one hand, Lattice-QCD calculations at quark masses heavier than found in Nature enable to assess whether Standard Model parameters might have to be finely tuned for nuclei to be stable. On the other hand, Lattice-QCD inputs are essential when experimental data are scarce, as in the determination of the nucleon axial form factor, hyperon-neutron interactions and three-neutron potential. I will present how our framework is suitable to study with unprecedented accuracy, properties medium-mass nuclei, the onset of hyperons in neutron stars, and neutrino-nucleus interactions. High-performance computing, which has proven to be essential for most of the recent advances in nuclear theory, is a key ingredient of our effort. Our quantum Monte Carlo codes efficiently scale on up to more than 250,000 MPI processes and are ready to best capitalize on European leadership-class computing facilities.

Speaker: Alessandro Lovato (TIFP)

Slides lovato_smft.pdf

15:00 Fundamendal physics studies in few-nucleon systems: the FBS project

The study of parity-violation (PV) and time-reversal violation (TRV) in nuclear processes may give important information on the weak and CP-violating interactions present in the Standard Model (SM), and also to be sensitive to beyond-SM Physics. In this contribution, we discuss the results of numerical studies of various few-nucleon PV and TRV observables, obtained using the facilities made available by the INFN HPC_HTC project. These studies are used to analyze the results of past and on going experiments, with the aim of extracting the values of fundamental PV and TRV coupling constants.

Speaker: Michele Viviani (PI)

Slides viviani_smeft17.pdf

15:20 Realistic Nuclear Shell Model and Double-Beta Decay: the STRENGTH project

The detection of the neutrinoless double-decay is nowadays one of the main goals in many laboratories all around the world, triggered by the search of ”new physics” beyond the Standard Model. I report on the calculation of the nuclear double-beta decay properties for nuclei that are possible candidates for such a process within the framework of the realistic shell model. The effective shell-model Hamiltonian and transition operators are derived by way of many-body perturbation theory without resorting to empirical effective quenching factors for the transition operators. The computational challenges of such an approach will be underlined. The reported research activity is carried in the frame of the STRENGTH (STructure and REaction Nuclei: towards a Global THeory) project of INFN.

Speaker: Nunzio Itaco (NA)

Slides ITACO_Itaco_smft.pdf

15:40 NEMESYS Project- Calibration of the fine-structure constant of graphene by time-dependent density functional theory.

One of the amazing properties of graphene is the ultra-relativistic behavior of its loosely bound electrons, mimicking massless fermions that move with a constant velocity, being inversely proportional to a fine-structure constant αg of the order of unity. The effective interaction between these quasi-particles is, however, better controlled by the coupling parameter α∗g =αg/ε, which accounts for the dynamic screening due to the complex permittivity ε of the many-valence electron system. This concept was introduced in a couple of previous studies [Reed et al., Science 330, 805 (2010), Gan et al., Phys. Rev. B 93, 195150 (2016)], where inelastic x-ray scattering measurements on crystal graphite where converted into an experimentally derived form of α∗g for graphene, over an energy-momentum region on the eV-Å−1 scale. Here, an accurate theoretical framework is provided for α∗g, using time-dependent density functional theory in the random phase approximation, with a cut-off in the interaction between excited electrons in graphene, which translates to an effective inter-layer interaction in graphite. The predictions of the approach are in excellent agreement with the above-mentioned measurements, suggesting a calibration method to substantially improve the experimental derivation of α∗g, which tends to a static limiting value of ∼0.14. Thus, the ab initio calibration procedure outlined demonstrates the accuracy of perturbation expansion treatments for the two-dimensional gas of massless Dirac fermions in graphene, in parallel with quantum electrodynamics.

Speaker: Antonio Sindona (CS)

Slides sindona

16:00 InDark: Inflation, Dark Matter and the Large-Scale Structure of the Universe

Investigating the interconnection between particle physics, cosmology and gravitational waves, in a multi-messenger approach, is one of the most promising research directions in modern physics. It allows studying inflationary models of the Early Universe, the nature of dark matter (DM) and dark energy (DE), or possible scenarios of modified gravity. Observations of the Cosmic Microwave Background (CMB) radiation - using Planck and future sub-orbital experiments - and of the Large-Scale Structure (LSS) of the Universe - via Euclid and other galaxy surveys - together with particle physics data from LHC, neutrino and dark matter experiments, and with the recent exciting detection of gravitational waves, provide the biggest joint dataset ever produced for the study of cosmology and fundamental physics. However, the computational challenges generated by this enormous quantity of data are significant, and pose severe limitations on the ability to extract all the information contained in this incredibly rich dataset. In this talk, we will focus on solutions and computational requirements to overcome such limitations, in order to answer outstanding, fundamental questions about our Universe.

Speaker: Alessandro Renzi (PD)

Slides Indark_bari.pdf

16:20 → 16:50 Coffee

16:50 → 18:30 Session 12

Convener: Guido Martinelli (ROMA1)

16:50 A summary of the 2017 HPC activities in Rome

I shall present a summary of some recent HPC activities in which people of the three Roma Universities are involved and an outlook of future plans.

Speaker: Giancarlo Rossi (ROMA2)

Slides ROSSI_bari.pdf

17:10 QCDLAT: new frontiers in lattice field theory for the Standard Model and beyond

I will review the research activity of the INFN group QCDLAT.

Speaker: Leonardo Giusti (MIB)

Slides GIUSTI_lgiusti_INFN.pdf

17:30 QFT_HEP on the lattice

We summarize the lattice activities within the I.S. QFT_HEP: concerning 'Quark Gluon Plasma', we focus on the LHC working region and study equation of state, topology and bottomonium suppression; for 'Strong Interaction Beyond the Standard Model', we study models with scale hierarchy which may be relevant for composite Higgs extensions of the SM, and we use our topology results to explore axion cosmology; finally ('Computational strategies and theoretical developments') we propose new approaches to spectral functions and to dense systems.

Speaker: Maria Paola Lombardo (LNF)

Slides LOMBARDO_BariDec2017_MpL.pdf

17:50 On usability of HPC systems

Recent multi- and many-core HPC processors are powerful processing units able to deliver computing performances in the order of one Teraflop. However, programming them efficiently to exploit a large fraction of available peak performance is not an easy task. This because application codes should be able to exploit several level of parallelism, and appropriate data-layouts should be used to store application data-domains. In this presentation I will discuss about data-layouts to enable efficient vectorizations of codes, taking into account as use case a fluid-dynamics application based on Lattice Boltzmann methods.

Speaker: Sebastiano Fabio Schifano (FE)

Slides SCHIFANO_schifano-bari17.pdf

18:10 NPQCD: Exploring the non-perturbative properties of fundamental interactions under extreme conditions.

I will present the recent research activities performed within the NPQCD project.

Speaker: Massimo D'Elia (PI)

Slides D'ELIA_talk_SMFT_2017.pdf

18:30 → 18:30 Closing