New Frontiers in Theoretical Physics - XXXV Convegno Nazionale di Fisica Teorica and GGI 10th anniversary

17 May 2016, 14:00 → 20 May 2016, 18:00 Europe/Rome

Galileo Galilei Institute, Firenze

     
 

Tuesday 17 May

GGI10th anniversary

1 Welcome

Speakers: Antonio Masiero, Fernando Ferroni, Guido Martinelli, Luigi Dei

2 Infrared and ultraviolet divergences in string theory

Speaker: Ashoke Sen

Slides Sen.pdf

3 Two applications of Nambu-Goldstone bosons in cosmology

Speaker: Lam Hui

16:20 Coffee break

4 CERN status and future plans

Speaker: Sergio Bertolucci

Slides Bertolucci.pdf

5 Exploring fundamental physics with gravitational waves

Speaker: Gian Francesco Giudice

Slides Giudice.pdf

6 TBA

Speakers: Alfred H. Mueller, Gabriele Veneziano, Roberto Casalbuoni

19:00 Welcome Reception

Wednesday 18 May

08:30 Registration

08:55 Welcome

Plenary 18 am

7 A curious story of quantum gravity in the ultraviolet

For the past 30 years nearly all theoretical physicists have believed that quantum field theories based on Einstein's general relativity necessarily must be ill-defined in the ultraviolet. This is the well known nonrenormalizability problem of gravity. But is it actually true in general? We describe recent calculations that cast doubt on this simple picture and show that quantum gravity is much tamer in the ultraviolet than believed possible. The new calculations make use of enormous advances in our ability to compute scattering amplitudes in quantum field theory. The relationship between gravity and gauge theory also offers a more general promise of simplifying Einstein’s Theory of General Relativity, as will be illustrated with black hole solutions.

Speaker: Zvi Bern (UCLA)

Slides Bern.pdf

8 Observations on Conformal Field Theories

We review some recent progress on the long-standing problem of characterizing second-order phase transitions. The symmetries of second-order transitions are now better understood. In addition, there are new general results about critical exponents, a better control of what happens when relevant operators are turned on, and some constraints on higher correlation functions. These new ideas can be tested in systems ranging from boiling water to quantum gravity in Anti-de Sitter space.

Speaker: Zohar Komargodski (Weizmann Institute of Science)

Slides Komargodski.pdf

10:20 Coffee break

Parallel Session 18 am: A

9 Hawking-like radiation from gravitational Bremsstrahlung beyond the Planck scale

We derive the limiting form of graviton radiation in gravitational scattering at transplanckian energies ($E \gg M_P$) and small deflection angles. We show that --- owing to the graviton's spin 2 --- such limiting form unifies the soft- and Regge- regimes of emission, by covering a broad angular range, from forward fragmentation to deeply central region. The single-exchange emission amplitudes have a nice expression in terms of the transformation phases of helicity amplitudes under rotations. As a result, the multiple-exchange emission amplitudes can be resummed via an impact parameter $b$-space factorization theorem that takes into account all coherence effects. We then see the emergence of an energy spectrum of the emitted radiation which, being tuned on $\hbar/R\sim M_P^2/E \ll M_P$, is reminiscent of Hawking's radiation. Such a spectrum is much softer than the one naively expected for increasing input energies and neatly solves a potential energy crisis. Furthermore, by including rescattering corrections in the (quantum) factorization formula, we are able to recover the classical limit and to find the corresponding quantum corrections. Perspectives for the extrapolation of such limiting radiation towards the classical collapse regime (where $b$ is of the order of the gravitational radius $R$) are also discussed.

Speaker: Dimitri Colferai (FI)

Slides colferai.pdf

10 The Cosmological Constant in Distorted Gravity

Even if a full and complete theory of Quantum Gravity and Quantum Cosmology is absent, the Wheeler-DeWitt equation appears as a natural instrument for the quantization of the gravitational field. In this context we setup a Sturm-Liouville problem with the cosmological constant considered as the associated eigenvalue. We will discuss the effects of some modifications of General Relativity, like Gravity's Rainbow, GUP and Horava-Lifshitz theory on the Wheeler-DeWitt Equation. An application to inflation will be discussed.

Speaker: Remo Garattini (MI)

Slides Garattini.pdf

11 String worldsheet, lattice and AdS/CFT

String sigma-models relevant in AdS/CFT are highly non-trivial two-dimensional field theories whose perturbative analysis is being crucially used to verify various conjectures, among which their integrability. I will discuss how to address the extraction of information at finite values of the string effective tension via the use of lattice-based methods.

Speaker: Valentina Forini

Slides Forini_GGI_2016.pdf

12 Towards a general formulation of the AdS/Ricci-flat correspondence

The AdS/Ricci-flat correspondence connects families of asymptotically AdS spacetimes to Ricci-flat spacetimes, and can be used to transfer tools and results between them. In its original formulation, this map requires a high degree of symmetry, limiting its possible applications. I will show how to extend the correspondence to a larger class of spacetimes, that includes for example general perturbations of Minkowski spacetime and of the Schwarzschild black hole.

Speaker: Marco Caldarelli (Southampton University)

Slides Caldarelli-2016.pdf

13 Newton-Cartan trace anomalies and non-relativistic local renormalization group

Trace anomalies for non-relativistic Schrodinger theories coupled to a Newton-Cartan background metric will be discussed. If the causality condition is not imposed on the metric, an infinite number of anomaly terms is allowed and a type A anomaly is present. If we restrict to background metric sources which preserve causality, there exists just a type B anomaly. Moreover I will discuss work in progress on the implementation of Osborn's local renormalization group in non-relativistic theories.

Speaker: Roberto Auzzi (P)

Slides auzzi-cortona-2016.pdf

14 Multiplet Recombination at Large N and Holography

We consider the coupling of a free scalar to a single-trace operator of a large N CFT in d dimensions. At leading order, the resulting RG-fow has a non-trivial fixed point where multiplets of the free scalar and the single trace operator recombine. We will show this phenomenon in field theory, and provide the dual holographic description. Free scalars correspond to singleton representations of the AdS algebra. The double-trace interaction is mapped to a boundary condition mixing the singleton with the bulk field dual to the single-trace operator. In the IR, the singleton and the bulk scalar merge, providing just one long representation of the AdS algebra.

Speaker: Mr Himanshu Raj (SISSA)

Slides Himanshu_GGI_May2016.pdf

Parallel Session 18 am: B

15 Large-N CP(N-1) sigma model on a finite interval and its boundary effect

We study the large-N solution of the bosonic CP(N-1) model on a finite interval with the Dirichlet conditions. In the literature, this model has been studied with translational invariant ansatz and there an existence of phase transition was found. We find that this translational invariant ansatz can not give a solution of the gap equation and divergence behavior appears around the boundaries, and resultantly the phase transition do not appear in this system.

Speaker: Keisuke Ohashi (P)

Slides OhashiCortuna2016.pdf

16 Non-dissipative corrections to energy-momentum tensor for a relativistic fluid

We show that the stress-energy tensor has additional terms with respect to the ideal form in states of global thermodynamic equilibrium in flat spacetime with non-vanishing acceleration and vorticity. These corrections are of quantum origin and their leading terms are second order in the gradients of the thermodynamic fields. Their relevant coefficients can be expressed in terms of correlators of the stress-energy tensor operator and the generators of the Lorentz group. With respect to previous assessments, we find that there are more second-order coefficients and that all thermodynamic functions including energy density receive acceleration and vorticity dependent corrections. We have calculated the corrections for a free real scalar field—both massive and massless- and also for complex scalar field and Dirac field with finite chemical potential, and are generally non-vanishing also for a free theory. Finally, these nonideal terms depend on the explicit form of the stress-energy operator, implying that different stress-energy tensors are thermodynamically inequivalent.

Speaker: Mr Eduardo Grossi (University of Florence & INFN Florence)

Slides Grossi-GGI-Cortona.pdf

17 Does Analog Computation Exist?

By establishing a relation between information erasure and continuous phase transitions we generalise the Landauer bound to analog computing systems. The entropy production per degree of freedom during erasure of an analog variable (reset to standard value) is given by the logarithm of the configurational volume measured in units of its minimal quantum. As a consequence every computation has to be carried on with a finite number of bits and infinite precision is forbidden by the fundamental laws of physics, since it would require an infinite amount of energy.

Speaker: Maria Cristina Diamantini (PG)

Slides Diamantini.pdf

18 Exact results from the Quench Action Method for a certain class of initial states

We continue the study of the Quench Action Method (QAM) for a recently considered geometrical quantum quench: two free fermionic chains initially separated by an hard wall and after put in contact and let evolve unitarily with a translation invariant Hamiltonian. Every time un unbalanced of energy, chemical potential or number of particles is present two different stationary regimes are reached at long times, depending on the ratio t/L, where t is the observation time scale and L is the total system size. To captured the two quasi-stationary states (before the quantum recurrence) with the QAM is necessary to distinguish the two case with the introduction of the time in the saddle point equation as just shown in a previous paper, and we show how this modication works also for a domain wall initial state. We compute the total time evolution for three different initial state of a XX chain, conjecturing that our master equation is valid for any initial state. We also review the derivation of the GGE state in the case of the two temperatures showing that this is an effect of finite volume, as for a domain wall initial condition.

Speaker: Mr Gabriele Martelloni (SISSA)

Slides MartelloniCortona2016.pdf

19 The quench action approach in finite integrable spin chains

We consider the problem of constructing the stationary state following a quantum quench, using the exact overlaps for finite size integrable models. We focus on the isotropic Heisenberg spin chain with initial state N\'eel or Majumdar-Ghosh (dimer), although the proposed approach is valid for an arbitrary integrable model. We consider only eigenstates which do not contain zero-momentum strings because the latter are affected by fictitious singularities that are very difficult to take into account. We show that the fraction of eigenstates that do not contain zero-momentum strings is vanishing in the thermodynamic limit. Consequently, restricting to this part of the Hilbert space leads to vanishing expectation values of local observables. However, it is possible to reconstruct the asymptotic values by properly reweighting the expectations in the considered subspace, at the price of introducing finite-size corrections. We also develop a Monte Carlo sampling of the Hilbert space which allows us to study larger systems. We accurately reconstruct the expectation values of the conserved charged and the root distributions in the stationary state, which turn out to match the exact thermodynamic results. The proposed method can be implemented even in cases in which an analytic thermodynamic solution is not obtainable.

Speaker: Dr Vincenzo Alba (SISSA)

Slides Alba.pdf

20 Topological superconductivity and Majorana edge modes in trionic phases

In this talk, I propose a new model that supports two-dimensional topological phases. The tight-binding model defined on the Lieb lattice with three different species of fermions supports a single Dirac-like point in the momentum space. The dispersion relation around this point is fully relativistic and described by a Duffin-Kemmer-Petiau Hamiltonian. I show the presence of topologically protected edge states by employing the entanglement spectrum. Importantly, these edge modes become Majorana modes by introducing suitable Cooper pairings in the lattice. This model represents the first example of topological superconductor in two-dimensional trionic phases.

Speaker: Dr Giandomenico Palumbo (University of Utrecht)

Slides PalumboNew.pdf

12:50 Lunch break

Plenary 18 pm

21 Hydrodynamic transport, laminar flow, and the AdS/CFT viscosity bound in a graphene field effect transistor

Graphene sheets encapsulated between crystals of boron nitride host a unique electron system that due to weak electron-phonon scattering allows micrometer-scale ballistic transport even at room temperature [1,2,3,4]. Above liquid nitrogen temperatures, these electron liquids are expected to display local equilibrium, enabled by strong electron-electron interactions [5]. Under these conditions, electrons in doped samples are expected to behave as a viscous liquid and may exhibit hydrodynamic phenomena akin to those observed in classical and quantum liquids. In this talk I will report on results of combined theoretical and experimental work [6,7] showing unambiguous evidence for this long-sought transport regime. In particular, I will discuss how high-quality graphene sheets in the Fermi liquid regime (k_B T ≲ E_F) exhibit an anomalous (negative) voltage drop near current injection points, which is attributed to the formation of whirlpools in the electron flow. Measurements of these quasi-local electrical signals enable to extract the value of the kinematic viscosity of the two-dimensional massless Dirac fermion liquid in graphene, which is found to be an order of magnitude larger than that of honey, in quantitative agreement with many-body theory [8]. Finally, I will discuss how our results near the charge neutrality point (k_B T≫ E_F) are compatible with the AdS/CFT viscosity bound [9,10]. Our work represents the first step towards the observation of nearly perfect fluidity and turbulence in solid-state devices.

Speaker: Marco Polini (Istituto Italiano di Tecnologia, Graphene Labs)

22 Statistical Aspects of Quantum State Monitoring

.....

Speaker: Denis Bernard (LPT-ENS & amp; CNRS)

Slides Bernard.pdf

23 Bulk/boundary correspondence in topological phases

Many of interesting physical (in particular topological) properties of topological phases of condensed matter can be "inferred" from their boundary (end, edge, surface, ..) field theories. In particular, the presence of quantum anomalies in boundary field theories (or lack thereof) provides a way to diagnose bulk topological properties. I will discuss such bulk/boundary correspondence in various examples in (3+1) d with or without bulk topological order. In particular, I will demonstrate that one can extract the so-called modular S and T matrices from boundary theories. These quantities encode important data of the bulk topological order such as braiding statistics of topological excitations in the bulk.

Speaker: Shinsei Ryu (University of Illinois at Urbana-Champaign)

Slides Ryu.pdf

16:40 Coffee break

Parallel Session 18 pm: A

24 Fluids from black holes

Even if fluid behavior is ubiquitous in physics, a complete and systematic description by means of a variational principle of an effective action is still lacking. In this talk I will show how progress can be done by rephrasing fluid dynamics in terms of certain Goldstone degrees of freedom and an underlying Schwinger-Keldysh structure and how this picture can be embedded in terms of slight perturbations of eternal black holes in Anti de Sitter spacetime within the holographic picture.

Speaker: Dr Natalia Pinzani Fokeeva (Technion)

Slides Natalia_Pinzani_Fokeeva.pdf

25 Chasing the cuprates with dylatonic dyons

In this talk we systematically review the therm-oelectric transport properties of hyperscaling violating holographic models exhibiting mechanism of momentum dissipation and we deeply analyse their possible application to the description of real world strongly coupled condensed matter systems, such as strange metals.

Speaker: Dr Andrea Amoretti (University of Cambridge, DAMTP)

Slides amoretti.pdf

26 Renyi entropy and conformal defects

After introducing the concept of Rényi entropy, we develop a field theoretic framework for calculating its dependence on the shape of the entangling surface in a conformal field theory. Our approach rests on regarding the corresponding twist operator as a conformal defect. We propose a simple constraint between the coefficient defining the two-point function of the displacement operator and the conformal weight of the twist operator, which consolidates a number of distinct conjectures on the shape dependence of the Rényi entropy. To conclude we give an explicit example for the free scalar in 4d and we comment on a recent holographic discrepancy.

Speaker: Dr Lorenzo Bianchi (Universität Hamburg)

Slides Lorenzo_Bianchi.pdf

27 Holographic computation of the Neutron electric dipole moment

We propose a computation of the Neutron electric dipole moment (NEDM), a well known quantity in QCD related to the "Strong CP problem", by means of the AdS/CFT correspondence. In particular we will use a setting of D8-anti D8 branes in a Type IIA background that goes under the name of Sakai-Sugimoto model. After a brief explanation of the physical interest behind this computation in QCD, we introduce the model, which in the case of our interest reduces to a Yang Mills - Chern Simons action. Finally the numerical solution is presented to first order in the CP breaking parameter theta and the quark masses (in the case of two degenerate flavors).

Speaker: Mr Andrea Manenti (Università di Pisa)

Slides Andrea_Manenti.pdf

Parallel Session 18 pm: B

28 Effects of magnetic fields on quark-antiquark interactions

I will discuss some recent results obtained in the study of the strong quark-antiquark interaction in the presence of intense external magnetic fields. At zero temperature the external field induces anisotropies in the static quark potential, that affect both the spectrum and the decays of the heavy mesons. In the quark-gluon plasma phase the screening masses do not show significant anisotropies but display a non-trivial dependence on the magnetic field.

Speaker: Andrea Rucci (P)

Slides Rucci.pdf

29 Applications of Jarzynski's theorem in lattice gauge theories

In lattice gauge theories many physical quantities, such as the pressure at finite temperature and zero baryon chemical potential in QCD, can be directly related to the computation of free energy differences. Jarzynski's theorem is a well-known equality in statistical mechanics which puts in relation the free energy difference between two equilibrium states with the fluctuations of the work performed during non-equilibrium transformations between these two states. In this talk an extension to lattice gauge theory of algorithms based on this relation is presented, along with numerical results for the interface in the $\Z_2$ gauge theory in three dimensions and for the equation of state for the non-Abelian SU(2) gauge theory.

Speaker: Alessandro Nada (TO)

Slides NADA.pdf

30 Quark number fluctuations in the strongly interacting medium

I will present a Lattice QCD determination of the zero density quark number fluctuations using the method of analytic continuation to imaginary chemical potential for temperatures ranging from 135Mev up to 350 Mev. I will discuss how these observables can be used to put bounds on the freeze-out curvature and to locate the second order critical point which is supposed to exist at finite baryon chemical potential.

Speaker: Giuseppe Gagliardi (Università di Pisa)

Slides Gagliardi.pdf

31 A Novel Approach to gamma_5 in Dimensional Regularization

A consistent definition of gamma_5 in Dimensional Regularization is essential both for model building and actual calculations. We propose a novel approach, where the extension of gamma_5 to generic D dimension obeys Lorentz covariance and cyclicity.

Speaker: Ruggero Ferrari (Milano U & INFN)

Slides ferrari_cortona_2016.pdf

Thursday 19 May

Plenary 19 am

32 The LHC challenge

I will discuss the challenge posed by the LHC results, including the 750 GeV excess.

Speaker: Andrea Romanino (SISSA)

Slides romanino.pdf

33 Tetraquarks, Pentaquarks and All That

I will review the experimental and theoretical status of the so called XYZ spectroscopy of exotic hadrons with particular attention to open questions and most recent findings. The existence of seemingly contradictory pictures to explain their nature partly reflects the itricacies of non-perturbative QCD.

Speaker: Antonio Davide Polosa (ROMA1)

Slides Polosa.pdf

10:20 Coffee break

Parallel Session 19 am: A

34 Spin degeneracy of Hadronic molecules in the heavy quark region

In the hadron spectroscopy in the heavy quark region, new symmetry plays an important role. The symmetry is the heavy quark spin symmetry. It manifests the mass degeneracy of the states with different total spin, e.g. the mass degeneracy of the heavy pseudoscalar and vector mesons. It is important to generate the exotic hadron structures found in the heavy quark region. The mass degeneracy enhances the mixing of $D$ ($J^P=0^-$) and $D^\ast$ ($J^P=1^-$) mesons. Therefore the pion coupling $\pi DD^\ast$ is introduced, while the coupling $\pi DD$ is forbidden. It is known that the one pion exchange potential (OPEP) is important for the binding of atomic nuclei. The attraction of the OPEP motivates us to investigate new meson-nucleus systems in the heavy quark region. In this talk, we study bound and resonant states of hadronic molecules of a heavy meson and a nucleon. In addition, the mass degeneracy can appear in not only the ordinary hadrons but also hadronic molecules. It indicates the existence of partner states of the heavy quark symmetry. We also discuss the properties of the hadronic molecules in the heavy quark limit.

Speaker: Yasuhiro Yamaguchi (GE)

Slides 5_19_GGI_yamaguchi.pdf

35 A non-supersymmetric model with unification of electro-weak and strong interactions

In this talk we present an example of an extension of the Standard Model where unification of strong and electroweak interactions occurs at a level comparable to that of the minimal supersymmetric standard model.

Speaker: Giancarlo Rossi (ROMA2)

Slides GGI_rossi.pdf

36 Exotic spectroscopy

We study the possibility that at least one of the two pentaquark structures recently reported by LHCb, can be described as a compact pentaquark state, and we give predictions for new channels that can be studied by the experimentalist if this hypothesis was correct. We use very general arguments dictated by symmetry considerations, in order to describe pentaquark states within a symmetry approach. A complete classification of all possible states and quantum numbers, that can be useful both to the experimentalists, for new finding, or to theoretical model builders are given, without the introduction if any particular dynamical model. Some prediction are finally given using a simple mass formula. We reproduce the mass and the quantum numbers of the lightest pentaquark state reported by LHCb (JP = 3/) state, with a parameters free mass formula fixed on known well established baryons. We predicted the other pentaquark resonances (giving their masses, and suggesting possible decay channels) which belong to the same multiplet of the discovered one. In the second part of the talk will be reviewed some intresting results on Heavy quarkonium hybrids, Phys.Rev. D78 (2008) 056003) with the identification of the Y(4260) as an hybrid state. Finally some results for the baryon spectroscopy within an Interacting quark diquark model for baryons ( Santopinto,Phys.Rev. C72 (2005) 022201) will be discussed.

Speaker: Dr Elena Santopinto (INFN)

Slides Elena_PENTA_GGI.pdf

37 Twin Supersymmetry

We will review Twin Higgs constructions in light of SUSY UV completions. Combining the Twin Higgs and SUSY provides a perturbative solution of the hierarchy problem in which the low-lying states stabilizing the EW scale are uncharged under the SM gauge group. We will discuss the fine tuning of the EW scale and the rich phenomenology of the Higg sector in a wide class of Twin SUSY models. We will see how models tuned at the level of 10-20 % can be easily obtained within this framework and discuss the crucial role played by the Higgs mass constraint. We then sketch some distinctive phenomenological features of this setup which can be relevant for future colliders.

Speaker: Dr Redigolo Diego (LPTHE_CNRS)

Slides Redigolo.pdf

38 Higgs mass and unified gauge coupling in the NMSSM with vector matter

We consider the NMSSM extended to include one vector-like family of quarks and leptons. If (some of) these matter particles, as the Higgs doublets, become strongly coupled to the singlet at a common scale Λ ~ 10-1000 TeV, this gives the correct enhancement of the tree level Higgs boson mass required to reach 125 GeV. It is conceivable that the Yukawa couplings to the singlet, although naively blowing up close to Λ, will not spoil gauge coupling unification. In such a case the unified coupling could be interestingly led to a value not far from unity, thus providing a possible explanation for the number of generations. The characteristic signal is an enhanced resonant production of neutral spin zero particles at LHC, that could even explain the putative diphoton resonance hinted by the recent LHC data at 750 GeV.

Speaker: Dario Buttazzo (Universität Zürich)

39 The determination of neutrino mass pattern and neutrino properties.

The determination of oscillation and, mainly, mass parameters is still a central problem of neutrino physics, having a great impact on elementary particle physics and astrophysics. After a brief review of the important steps forward of the last 10-15 years, we focused on the central issue of the mass hierarchy determination. We discuss some related theoretical aspects, the present state of art, the main recent experimental results obtained in this field and the potentialities of future experiments, with particular attention to the JUNO experiment, that should start taking data in China in a few years from now.

Speaker: Vito Antonelli

Slides Antonelli-cortona-16-finale.pdf

Parallel Session 19 am: B

40 Some properties of Born-Infeld theories

In this talk I'd like to investigate some properties of Born-Infeld theories. I start from a linear form of the Lagrangian in terms of auxiliary fields as introduced in [arXiv:1412:6786]. Depending of the scalar fields coset manifold, integrating out the auxiliary fields yields various Born-Infeld type Lagrangians with different symmetry group.

Speaker: Dr Bianca Letizia Cerchiai (Centro Fermi Roma e Politecnico di Torino)

Slides Cerchiai.pdf

41 Constrained superfields in SUSY and SUGRA

When supersymmetry is broken and nonlinearly realized, one may remove from the spectrum of the theory various component fields. This is achieved by introducing appropriate constraints to the various superfields. We discuss the coupling of the nilpotent Goldstino superfield to supersymmetry and supergravity, and to matter superfields. We also give a generic setup within which one can remove any component field from the spectrum. We also discuss applications to inflationary cosmology.

Speaker: Dr Fotis Farakos (University of Padova)

Slides nilpotent-sugra-FARAKOS.pdf

42 Hidden Gauge Structure of Supersymmetric Free Differential Algebras

In this talk I will present a detailed investigation of the gauge algebra hidden in all free differential algebras in supersymmetric theories, focusing in particular on the minimal D=7 supergravity case, where the hidden structure is particularly rich. I will also discuss its relation with the 11-dimensional theory.

Speaker: Lucrezia Ravera (TO)

Slides Ravera.pdf

43 Bound states of 5d spinning black holes from 6d rotating black strings.

We find and study BPS bound states of spinning black holes in 5d asymptotically flat spacetime. These solutions follow from multi-string solutions in six-dimensional minimal supergravity and can be uplifted to F- or M-theory. We analyze the regularity conditions and work out the example of a bound state of two black holes in detail. The bound state is supported by fluxes through nontrivial topologies exterior to the horizons and KK momentum. Furthermore, we determine the entropy and compare with other macroscopic BPS solutions.

Speaker: Flavio Porri (Utrecht University)

Slides Porri_Cortona2016.pdf

44 Multimetric Supergravities

In the last few years a new class of theories has been discovered consistently describing massive spin-2 fields nonlinearly interacting with a single massless one. These multimetric gravities provide a solution to the problem of the so-called Boulware-Deser ghost, previously thought to unavoidably plague any interacting theory of massive spin-2 particles. We note that their action in the vielbein formulation admits a natural extension in terms of integral forms on a supermanifold, which will be locally supersymmetric by construction, and thus will describe a new class of couplings between supergravity and massive spin-2 multiplets. We propose superfield actions for N=1 multimetric supergravities in spacetime dimensions up to four, and discuss the problems related to their component expansion, comparing them with the simpler case of multi-gauge fields.

Speaker: Fabrizio Del Monte

45 Symmetries on Every Black Hole Horizon

In this talk I will show that every Black Hole Horizon possesses an Asymptotic Symmetry Group (ASG) whose group structure is non trivial. I will begin with an introduction on known asymptotic symmetries, both at the Horizon and at the Null Infinity of Asymptotically Flat Spacetimes, a.k.a. the BMS group. Therefore I will describe the ASG in all the details, stating it as a Theorem. Briefly, the statement is that "every stationary Killing causal-disconnetting Horizon has an ASG, regardless of spacetime Dimensions, Cosmological Constants and Classical Conserved Charges associated to it". I then will show the similarities between the ASG and BMS, focusing on the poorly known differences and I will end up with a brief discussion on the Classical Central Extension of the Charge Algebra.

Speaker: Alessandro Bombini (FI)

Slides Presentazione_Bombini.pdf

12:50 Lunch break

Plenary 19 pm

46 Particle Physics on the lattice

We discuss the relevance of lattice computations in precision tests of the Standard Model, with emphasis on heavy Flavor Physics and Higgs Physics. After a short introduction to the lattice methodology, we present recent computations of low energy hadronic parameters (decay constants and form factors) and quark masses. We do that by describing the FLAG initiative, its scope and the choice of rating criteria used to assess the quality of different calculations. That should make clear that the precision reached for a number of quantities is such that electromagnetic (EM) corrections, beyond the point-like approximation, are becoming relevant. We discuss recent computations of the spectrum based on direct simulations of QED+QCD. We also present theoretical developments for including EM effects in leptonic decays.

Speaker: Michele Della Morte (Dept. Of Mathematics and Computer Science, University of Southern Denamrk)

Slides DellaMorte.pdf

47 Dual formulation of lattice field theory

In recent years considerable progress was made with exactly rewriting lattice field theories in terms of dual variables. These variables are loops for matter fields and surfaces for the gauge degrees of freedom. In terms of the dual variables we can access problems with Monte Carlo simulations that are not tractable in the conventional formulation, in particular systems with chemical potential and models with a vacuum angle. I give an overview over the dual approach and discuss some of the new results.

Speaker: Christof Gattringer (University of Graz)

Slides talk_gattringer.pdf

Parallel Session 19 pm1: A

48 Hagedorn spectrum and thermodynamics of SU(2) and SU(3) Yang-Mills theories

We discuss the equation of state in the confining regime of SU(N) Yang-Mills theories in (2+1) and (3+1) dimensions. We show that the results are described very well by a gas of massive, non-interacting glueballs, provided one assumes that, in addition to the known particles lighter than the two-particle threshold, the theory features a physical spectrum described by an exponentially growing Hagedorn density, which can be modeled by a bosonic closed-string model.

Speaker: Michele Caselle (TO)

Slides caselle.pdf

49 Theta dependence in the deconfined phase of QCD

We will present a determination of the topological properties of QCD for temperatures above the deconfinement, up to T~600MeV. Numerical results obtained by means of Lattice QCD simulations will be compared with the prediction of instanton gas calculations. Finally, the implications of these results for the cosmological bounds on the axion mass will be discussed.

Speaker: Claudio Bonati (PI)

Slides slides_bonati.pdf

Parallel Session 19 pm1: B

50 Diphoton production at the LHC

We review selected theoretical results for diphoton production at the LHC concerning Standard Model studies and new physics searches, at the light of the recent 750 GeV excess.

Speaker: Leandro Cieri (University Zürich)

Slides Cieri_2016_GGI.pdf

51 Di-photon resonance and Dark Matter as heavy pions

Vectorlike Confinement is one of the simplest and most plausible scenarios for new physics beyond the SM, obtained by adding new fermions in vectorlike representations of the SM gauge group, with a mass scale possibly accessible at the LHC. These fermions are charged under a new gauge strong interaction that confines without breaking the SM gauge symmetry. The new physics is not related to the electroweak scale and is not constrained by electroweak precision tests and flavor physics. The phenomenology of Vectorlike Confinement theories is very rich and can give rise to good Dark Matter candidates as well as to a scalar that could fit the di-photon excess that appeared in the Run-2 LHC data. Assuming that the di-photon excess at 750 GeV is true, I will discuss models where both the Dark Matter and the di-photon candidates are given by techni-pions with typical mass below the TeV.

Speaker: Mrs Elena Vigiani (Università di Pisa)

Slides vigiani2016.pdf

16:40 Coffee break

Parallel Session 19 pm 2: A

52 The topological susceptibility in the large-N limit of Yang–Mills theory.

We present preliminary results for the topological charge susceptibility of SU(N) Yang–Mills theory in the large-N limit. This observable enters the Witten–Veneziano formula and gives the anomalous contribution to the η' meson mass in this limit. The computation is done on the lattice implementing the gradient flow definition of the topological charge, which is proven to coincide with the correct field-theoretic quantity in the continuum limit. High-statistics Monte Carlo simulations of lattice-regularized SU(N) Yang–Mills theory, with N=3, 4, 5, 6 and for three different lattice spacings, has been performed. Open boundary conditions in the time direction are employed to avoid the freezing of the topological charge both for finer lattices and larger N. This allows us to extrapolate the result to the continuum limit and to the N→∞ limit with confidence, keeping all the systematics negligible with respect to the statistical error.

Speaker: Marco Cè (SNS & INFN, Pisa)

Slides CortonaCè.pdf

53 The Critical Line of the QCD phase diagram from Lattice QCD

The phase diagram of QCD at finite density can be studied both experimentally and by theoretical means. While, from the experimental point of view, it is possible to obtain information from heavy ion collision experiments, from the theoretical point of view the only possible first-princlple approach are Lattice QCD Montecarlo simulations. Unfortunately, at nonzero baryon density current algorithms are affected by a sign problem. Nonetheless, in the regime where the baryon chemical potential $\mu_B$ is sufficiently small, it is possible to make predictions for the dependence of the critical temperature $T_c$ on $\mu_B$, that is the so-called "critical line" of QCD. I will discuss our latest results in this regard and compare them with the literature.

Speaker: Michele Mesiti (PI)

Slides Mesiti_cortona2016.pdf

54 Precision determination of b-quark mass and pseudoscalar B-decay constants

We will present precise determinations for the b-quark mass, the quark mass ratios mb/mc and mb/ms as well as the leptonic B-decay constants employing lattice QCD methods. We use the gauge configurations with four dynamical quark flavors, up/down, strange and charm, generated by the European Twisted Mass Collaboration. Our results, obtained at three values of the lattice spacing, are extrapolated to the physical pion mass and to the continuum limit.

Speaker: Petros Dimopoulos (Centro Fermi, Museo Storico della Fisica e Centro Studi e Ricerche "Enrico Fermi")

Slides Dimopoulos_GGI.pdf

55 Heavy-light flavour physics: D*(s) and B*(s) mesons decay constats in lattice QCD

In this talk the results of a lattice QCD calculation of the vector mesons decay constants are presented. They are relevant hadronic parameters that characterize the internal structure of vector mesons due to QCD interactions, for instance they can provide phenomenologically good descriptions of non-leptonic decay rates within the factorization approximation. The two previous lattice calculations for these parameters show a 10% difference, the presented results point to a possible explanation of the existing tension. The analysis is based on the extraction of mesons masses and decay constants from the two-point correlation functions coming from unquenched simulations of the European Twisted Mass Collaboration (ETMC) with Nf = 2+1+1 dynamical quarks. These are particularly suitable for charm physics, as the strange and charm quark masses are close to their physical values. Otherwise the extension to the beauty-sector requires an extrapolation, in order to do that, the ETMC ratio method has been applied.

Speaker: Ms Aurora Melis (RomaTre University of Rome)

Slides Melis.pdf

Parallel Session 19 pm 2: B

56 Wide composite vector resonance at the LHC

Heavy Vector resonances are a general prediction of Composite Higgs Theories, where the Higgs arises as a pseudo Nambu Goldstone Boson. Typically at the LHC these states are sought for via narrow resonant searches, looking for "bumps" in the dilepton invariant mass spectrum. These states can however undergo decays into a pair of top partners in a large and natural range of Composite Higgs theories parameter space, thus evading current LHC limits. We however show how, by reinterpreting LHC analyses designed for top partners searches, strong limits can be set on these otherwise elusive resonances, highlighting the prospect for these searches at the run-2 of the LHC.

Speaker: Dr Daniele Barducci (LAPTh, Universite Savoie Mt. Blanc)

Slides barducci_cortona.pdf

57 Totally Asymptotically Free Trinification

Reinterpreting the naturalness principle, we address the hierarchy problem, proposing a phenomenologically interesting extension of the SM with a gauge group $SU(3)_L\otimes SU(3)_R\otimes SU(3)_c$, such that all the gauge, Yukawa and quartic couplings can be extrapolated up to infinite energy. We analyze which set of scalar or fermionic particles are needed to accomplish this goal. Finally, we consider the predictions of these models about the recently measured diboson and diphoton anomalies.

Speaker: Giulio Maria Pelaggi

Slides PelaggiCortona.pdf

58 Symmetry Breaking by Topology and Energy Gap

A symmetry breaking mechanism is discussed which exhibits radically different properties compared with the Goldstone and the Higgs mechanisms: the interplay between symmetries of a quantum system and the topology of the manifold of particle configurations can account for both the breaking of an internal symmetry and the presence of an energy gap. Such features are clearly displayed by the quantum particle on a circle and the Bloch electron, for instance. In fact, the fundamental group of the manifold of the positions of the quantum system gives rise to elements of the center $\mathcal Z$ of the observable algebra: symmetries that do not commute with the topological invariants represented by elements of $\mathcal Z$ are then spontaneously broken in each irreducible representation of the observable algebra compatibly with an energy gap.

Speaker: Dr Carlo Heissenberg (SNS)

Slides Slides_GGI_Heissenberg.pdf

59 QED in the background of evaporating black holes

Far away from black holes, one might expect that quantum field quantization performed in Minkowski space is a good approximation. Indeed, all experimental tests in the particle colliders reveal no deviations so far. Nevertheless, black holes should leave imprints of their presence in quantum processes. In this talk, we shall discuss several imprints of small evaporating black holes in QED in the weak gravity regime.

Speaker: Dr Viacheslav Emelyanov (Karlsruhe Institute of Technology)

Slides Emelyanov.pdf

19:15 Social Dinner

Friday 20 May

Plenary 20 am

60 Open issues in Cosmic Ray Physics

I will summarize current open issues in the acceleration and transport of Galactic cosmic rays, and analyse the implications for the transition from Galactic to extragalactic cosmic rays. Special emphasis will be given to the role of non-linear effects induced by cosmic rays for transport both inside accelerators and in the Galaxy.

Speaker: Dr Pasquale Blasi Blasi (INAF/Osservatorio Astrofisico di Arcetri)

61 The story of a simpler universe

Because of the non-detection of primordial gravitational waves, our universe has just gotten a bit simpler. I discuss how this comes about within the theory of inflation and how conformal symmetry comes to play an increasingly important role. An astounding fact about our universe is that the spatial distribution of anything we have observed on large scales seem to originate from a single scalar field, the "adiabatic" mode. The current explanations are polarized in two camps: symmetry and thermalization. After reviewing the complexity of our UV-models, I speculate that we might have chosen the wrong camp.

Speaker: Enrico Pajer (Utrecht University)

Slides Pajer.pdf

10:20 Coffee break

Parallel 20 am: A

62 Giant Monopoles as a Dark Matter Candidate

I will review recent challenges to WIMP dark matter models and describe how some of them are addressed by giant 't Hooft-Polyakov monopole models. These models exist in theories with a dark sector including a dark SU(2) gauge symmetry coupled to an adjoint Higgs and two fundamental fermions. Several consistency checks of such models will be described, including consistency with MACHO bounds and the CMB power spectrum. The main prediction of such models, which can soon be tested using GAIA astrometry data, is that dwarf galaxies are embedded in halos which extend for tens of kpc, often beyond their tidal radii, which would be impossible for gravitationally bound particulate dark matter.

Speaker: Prof. Jarah Evslin (Institute of Modern Physics, CAS)

Slides Evslin.pdf

63 WIMP Dark Matter at gamma-ray telescopes

Weakly interactive massive particles (WIMP), as candidates of Dark Matter, motivate new physics at the TeV scale independently of electroweak naturalness. What will be the role of gamma-ray telescopes in probing this paradigm, also in comparison with other experiments, like colliders? I will examine this question in the case of electroweak multiplets, which constitute a WIMP ``prototype’’, and are further motivated by Supersymmetry and Minimal Dark Matter. This will bring me to discuss our understanding of the DM properties in the Milky Way, and in particular the directions in which we need improvements, in order to best exploit telescopes like Fermi, HESS and CTA.

Speaker: Mr Filippo Sala (LPTHE Paris)

Slides FSala_WIMPs.pdf

64 Inflation with weakly broken Galileon symmetry

In Effective Field Theories (EFT), symmetries (exact and approximate) play a key role in legitimizing the size and the hierarchy of the Wilson coefficients. With this in mind, in the context of the EFT of single-field inflation, we will study the theoretical and phenomenological consequences of a weakly broken Galileon symmetry, providing novel inflationary scenarios in a class of accelerating backgrounds, largely insensitive to loop corrections because of some curved-space remnant of the non-renormalization theorem for flat-space Galileons. This guarantees the quantum robustness of the classical solutions and the technical naturalness of the couplings. In particular, we will analyse the novel physical consequences and compare the predictions to the recent observational results.

Speaker: Luca Santoni (PI)

Slides santoni.pdf

65 Weakly coupled baryonic dark matter

In this talk I will describe Dark Matter (DM) arising as a composite state of a new confining gauge force and stable thanks to accidental symmetries, as recently proposed in the context of theories with new vector-like fermions. Differently from previous works, I will focus on the regime where the fermion masses are larger than the confinement scale. In this scenario DM is a baryonic non-relativistic bound state formed due to perturbative forces. I will consider both DM as a Majorana and as a Dirac fermion leading to completely different phenomenology. Due to the perturbative value of the gauge coupling the thermal relic abundance can reproduce the critical DM density for masses around the TeV scale, possibly also accessible by the LHC.

Speaker: Andrea Mitridate (INFN)

Slides Mitridate.pdf

66 Gravitational waves from coalescing relativistic binaries

The direct detection by the LIGO detector of the gravitational waves emitted by a coalescing black hole binary (GW150914) has marked the beginning of gravitational wave astronomy. Motivated by the recent experimental result, I will review recent results about analytical effective-one-body (EOB) approach to the general-relativistic two-body dynamics, notably its completion using numerical relativity (NR) simulations, stressing its necessity to compute the (thousands of) analytical waveform templates needed for the actual data analysis of GW events like GW150914. I will mainly report on recent result about the EOB(NR) approach concerning: (i) the coalescence of (spinning) black hole binaries (BBHs), showing the performance of a recently completed, NR-informed, EOB model (arXiv:1506.08457) able to generate highly faithful waveform from the quasi-circular inspiral, through plunge, merger and ringdown; (ii) the coalescence of neutron star (NS) binaries, with particular emphasis on the modelization of tidal effects up to merger, whose measurability in gravitational wave experiments will allow us to put strong constraints on the equation of state of ultra-dense matter; (iii) the strong-field scattering of BBHs as a useful numerical laboratory to extract strong-field information to complete the EOB analytical model. A class of effective-one-body waveform templates for coalescing BBHs, similar to the one I will discuss during the talk, has been crucially used in the recent analysis of the gravitational wave event GW150914

Speaker: Dr Alessandro Nagar (IHES)

Slides nagar_ggi.pdf

67 Is the gravitational-wave ringdown a probe of the event horizon?

It is commonly believed that the ringdown signal from a binary coalescence provides a conclusive proof for the formation of an event horizon after the merger. This expectation is based on the assumption that the ringdown waveform at intermediate times is dominated by the quasinormal modes of the final object. We point out that this assumption should be taken with great care, and that very compact objects with a light ring will display a similar ringdown stage, even when their quasinormal-mode spectrum is completely different from that of a black hole. In other words, universal ringdown waveforms indicate the presence of light rings, rather than of horizons. Only precision observations of the late-time ringdown signal, where the differences in the quasinormal-mode spectrum eventually show up, can be used to rule out exotic alternatives to black holes and to test quantum effects at the horizon scale.

Speaker: Edgardo Franzin (C)

Slides Cortona@GGI2016_Franzin.pdf

Parallel 20 am: B

68 Framing and localization in Chern-Simons theories with matter

Supersymmetric localization provides exact results that should match QFT computations in some regularization scheme. The agreement is particularly subtle in three dimensions where complex answers from the localization procedure sometimes arise. I will introduce this problem in the case of 1/6 BPS Wilson loops in ABJ(M) theory. I will show how the localization results are reproduced perturbatively and argue that the imaginary parts originates entirely from a non--trivial framing of the circular contour. Contrary to pure Chern-Simons theory, for ABJ(M) the framing phase is a non--trivial function of the couplings and potentially receives contributions from vertex-like diagrams. The intimate link between the exact framing factor and the Bremsstrahlung function of the 1/2-BPS cusp is also discussed.

Speaker: Andrea Mauri (M)

Slides Mauri_Cortona_2016.pdf

69 Surprises from the resummation of ladders in the ABJ(M) cusp anomalous dimension

We study the cusp anomalous dimension in N=6 ABJ(M) theory, identifying a scaling limit in which the ladder diagrams dominate. The resummation is encoded into a Bethe-Salpeter equation that is mapped to a Schroedinger problem, exactly solvable due to the surprising supersymmetry of the effective Hamiltonian. In the ABJ case the solution implies the diagonalization of the U(N) and U(M) building blocks, suggesting the existence of two independent cusp anomalous dimensions and an unexpected exponentiation structure for the related Wilson loops. While consistent with previous perturbative analysis, the strong coupling limit of our result does not agree with the string theory computation, emphasizing a difference with the analogous resummation in the N=4 case.

Speaker: Dr Michelangelo Preti (Università degli Studi di Parma)

Slides GGI-Preti.pdf

70 Susy Scattering amplitudes, Wilson loops and integrability.

The gluon scattering amplitudes and the null polygonal Wilson loops in planar Super Yang-Mills N=4 are believed to be the same. Many tests have been done at the perturbative level, while at strong coupling the scattering amplitudes can be computed solving a minamal area problem, thanks to the AdS/CFT correspondence. As for the Wilson loops, a variant of the well-known Operator Product Expansion has been developed enabling us to write it as a sum over the excitations on the GKP vacuum. Thanks to the integrability underlying the theory, we have been obtaining many exact results in a series of papers, mainly on the strong coupling limit. Among them, the computation of the Wilson loop is recast into a system of TBA-like equations, finding agreement with the classical string result. In addition, a purely quantum contribution of the same order of the classical one comes out of the blue by considering an ostensibly sub-dominant sector.

Speaker: Alfredo Bonini (BO)

Slides Slides-Bonini.pdf

71 Higgs-regulated amplitudes in N = 4 SYM, the generalized cusp anomalous dimension and bound states of W-bosons

We consider massive scattering amplitudes on the Coulomb branch of N = 4 SYM theory, obtained by giving a general vacuum expectation value to the scalars fields of the theory. Dual conformal invariance is still present in four-point amplitudes and the generalized cusp anomalous dimension characterizes its planar IR divergencies. The angle theta measures the relative orientation for Coulomb branch expectation values associated to pairs of external W-bosons. We check explicitly at three-loop the expected expression of the cusp anomalous dimension. Furthermore, using Regge theory and dual conformal invariance, we discuss bound states of W-bosons as functions of theta, both at weak and strong coupling.

Speaker: Silvia Davoli (PR)

Slides Silvia_Davoli.pdf

72 Asymptotic Freedom versus Planar Duality in Gauge and String Theories

For large-N confining asymptotically-free gauge theories with no perturbative mass scale we investigate the compatibility between the asymptotic freedom of the S-matrix and the planar duality of disk amplitudes of their would-be string solutions. Several implications for any would-be string solution of large-N QCD with massless quarks follow.

Speaker: Marco Bochicchio (ROMA1)

73 Cubic interactions for Maxwell-Like higher spins

After a brief review of the interaction problem in higher-spin theory, I will illustrate the construction of cubic vertices for higher-spin gauge fields described at free level by a new class of Lagrangians, termed Maxwell-like. The latter generalise the Fronsdal formulation to the case of reducible multiplets of massless particles and can be shown to be directly related to free tensionless strings. The deformation of the constrained gauge symmetry of Maxwell-like theories requires a generalisation of the Noether procedure, that I will also illustrate.

Speaker: Mr Gabriele Lo Monaco (Università di Pisa)

Slides Lo_MOnaco.pdf

12:50 Lunch break

Plenary 20 pm

74 Gravity at large scales

We will review recent attempts at modifying gravity at cosmological scales, largely motivated by the aim of providing a dynamical explanation for dark energy. We will see that it is quite challenging to construct infrared modifications of gravity that are both theoretically consistent and cosmologically viable. We will finally present some work of our group on effective nonlocal modifications of GR, that appear to work remarkably well at a phenomenological level, and raises interesting questions from the field-theoretical point of view.

Speaker: Prof. Michele Maggiore Maggiore (Geneva University)

Slides Maggiore.pdf

75 Advanced detectors of gravitational waves: status and perspectives

After the first direct detection of gravitational wave we entered in the new era of gravitational wave astronomy. New kind of sources are expected to be found, and the future steps toward improved detectors' sensitivities will allow to extract physical information in a more and more accurate way. I describe the status of current network of detectors, the more important sources of noise that limit the sensitivity and the proposals to overcome them. Finally I will discuss foreseen future improvements, next generation detectors and perspectives.

Speaker: Giancarlo Cella (INFN PIsa)

Slides AdvancedDetectorsCella.pdf

76 GW150914: The Birth of Gravitational-Wave Astronomy

The detection by LIGO of GW150914 marks the beginning of a new era in physics and astrophysics. I will review theoretical work that paved the way to observe such a gravitational-wave signal and discuss the results of the discovery focusing on its gravitational, astrophysical and fundamental physics aspects.

Speaker: Alessandra Buonanno

16:40 Coffee break. Discussion: Cortona 2018