Theoretical Particle Physics

TPP Journal Club History
Date	Room	Speaker	Title
Sep 20 2013 14:00	SISSA - Room 137	Alessandro Sfondrini (Utrecht University)	Integrability for the AdS3/CFT2 correspondence
ABSTRACT: Some physical systems enjoy a number of symmetries large enough to completely constrain their dynamics, and are therefore called “integrable”. It is a remarkable fact that some string theories on Anti-de Sitter (AdS) backgrounds seem to have this property. This feature, first explored for type IIB strings on AdS_5xS^5, allowed in that case to find the full energy spectrum of the strings, which by the AdS/CFT duality gives the two-point functions of primary operators in the dual D=4, N=4 superconformal theory.\r\nI will review these integrability techniques and discuss how they can be used to explore string theories on AdS3 x S^3 x T^4 and AdS_3 x S^3 x S^3 x S^1 and to find (part of) their world-sheet S-matrices, which in turn yield the spectrum through the Bethe-Yang equations. This presents new challenges with respect to the AdS5 case, and offers interesting insights in the yet-to-be-understood dual conformal field theories, through a spin-chain picture.
Sep 06 2013 14:00	SISSA - Room 137	Hiroaki Sugiyama (Maskawa Institute for Science and Culture, Kyoto Sangyo University)	Lepton number violation at the LHC with leptoquark and diquark
ABSTRACT: If neutrinos are Majorana particle, lepton number violating processes are possible. Such processes are usually searched for in low energy experiments, namely, neutrinoless double beta decay searches. We investigate a different possibility that lepton number violation is discovered at LHC. We show such a possibility in a model where leptoquark scalar and diquark scalar are introduced. Neutrino masses are generated at the two-loop level and suppressed appropriately.
May 31 2013 14:00	SISSA - Room 137	Giorgio Busoni (SISSA)	On the Minimum Dark Matter Mass Testable by Neutrinos from the Sun
ABSTRACT: We discuss a limitation on extracting bounds on the scattering cross section of dark matter with nucleons, using neutrinos from the Sun. If the dark matter particle is sufficiently light (less than about 4 GeV), the effect of evaporation is not negligible and the capture process goes in equilibrium with the evaporation. In this regime, the flux of solar neutrinos of dark matter origin becomes independent of the scattering cross section and therefore no constraint can be placed on it. We find the minimum values of dark matter masses for which the scattering cross section on nucleons can be probed using neutrinos from the Sun. We also provide simple and accurate fitting functions for all the relevant processes of GeV-scale dark matter in the Sun.
May 10 2013 11:00	SISSA - Room 137	Petr Vasko (SISSA)	Application of the two sphere partition function: the quintic threefold
ABSTRACT: In the first part of the talk I will briefly review the arguments of arXiv:1210.6022 why the two-sphere partition function of a N=(2,2) supersymmetric gauge theory corresponding to a nonsingular compact Calabi-Yau manifold (as target space of the nonlinear sigma model in the IR) is supposed to compute the quantum Kahler potential of that CY. In the second part I will show in detail how this formalism works on the example of a quintic threefold. This computation is motivated by arXiv:1208.6244, however rather than computing the Kahler potential directly, I will compute the so called I-function (which plays a major role in the Givental's approach to mirror symmetry in mathematics). If time allows I will also extract some interesting information from it, like the mirror map and Gromov-Witten invariants.
May 03 2013 14:00	SISSA - Room 137	Antonio Sciarappa (SISSA)	N = (2,2) gauge theories on the two-sphere
ABSTRACT: I will review the papers 1206.2356, 1206.2606, which explain how to construct N = (2,2) supersymmetric gauge theories on the two-sphere with vector and chiral multiplets. Via supersymmetric localization, it is also possible to compute exactly their partition function. This admits two representations, depending on the choice of localization term: one as an integral over the Coulomb branch, and the other as a sum over vortex and antivortex excitations on the Higgs branches. Possible applications will be discussed.
Apr 19 2013 11:00	SISSA - Room 137	Muhammad Nouman Muteeb (SISSA)	Localization and Supersymmetric Gauge Theories
ABSTRACT: We will describe the general idea of supersymmetric localization and then following arXiv:0909.4559 we will apply the localization technique to calculate exact results for some quantities in supersymmetric theories on a curved manifold.
Apr 12 2013 14:00	SISSA - Room 137	Victor Ivan Giraldo Rivera (SISSA)	Rigid Supersymmetry on curved 4d manifolds
ABSTRACT: We will describe the general arguments of arXiv:1105.0689 and arXiv:1109.5421 in which rigid N=1 supersymmetric sigma models are constructed.The result is obtained through the use of the N=1 minimal supergravity multiplet as a background superfield. Specifically the auxiliary fields in the gravity multiplet are not integrated out and the constraints on them determine the background one ends up with.
Mar 08 2013 11:00	SISSA - Room 137	Dan Xie (IAS, Princeton)	Higher laminations, webs, and N=2 line operators
ABSTRACT: A classification of half-BPS line operators of four dimensional N=2 theory engineered from six dimensional A_{N-1} (2,0) theory on a punctured Riemann surface is given by the lamination space of the corresponding local system. These line operators are represented by M2 brane wrapped on bipartite webs formed by three junctions on the Riemann surface. We also calculate the expectation value of these line operators.
Feb 22 2013 11:00	SISSA - Room 137	Lorenzo Di Pietro (SISSA)	A refinement of entanglement entropy and the number of degrees of freedom
ABSTRACT: The topic is (part of) arXiv:1202.2070. In the paper, it is shown how to extract the universal, divergence-free contribution to the entanglement entropy of a QFT across a spatial region of size R. The properties of this R-dependent coefficient are derived, and general results are established on its small and large R limits. In the case of a spherical entangling region, those properties make it a valid candidate for a C-function in any dimension. This conjecture is explored in gravity duals of 3d and 4d theories, using the holographic prescription to calculate entanglement entropy.
Feb 15 2013 11:00	SISSA - Room 137	Piermarco Fonda (SISSA)	Holographic Entanglement Entropy and c-theorems in higher dimensions
ABSTRACT: Based on results of arxiv:1202.2068. The use of holographic techniques in order to study the RG flows of QFTs is well established. Motivated by the idea of arXiv:0610.375 (reviewed in Alejandro Cabo Bizet's talk) of using entanglement entropy (EE) to define an alternative for the c-function in 2D QFTs and given the recent results - which will as well be discussed - in holographic computations of EE for arbitrary dimensions, it is possible to define a candidate for a generalized c-function from the EE evaluated for a strip of infinite length. The (numerical) results obtained will be discussed in both cases when the gravity side is assumed to be governed by Einstein-Hilbert action or by Gauss-Bonnet gravity.
Feb 08 2013 11:00	SISSA - Room 137	Alejandro Cabo Bizet (SISSA)	C-Theorem: Two "physical" proofs
ABSTRACT: Mainly I will review the key points behind two significant proposals of proof of the C-theorem in 2D RG flows. The first one by Komargodski (arXiv:1112.4538 [hep-th]) mainly based on conformal invariance and QFT unitarity arguments, and the second one by Casini and Huerta (arXiv:cond-mat/0610375 [cond-mat.stat-mech]) based on Lorentz Invariance and a universal property of Entanglement Entropy that allows to use it in the construction of a faithful candidate for c-function in 2D RG flows.
Feb 01 2013 11:00	SISSA - Room 137	Francesco Caracciolo (SISSA)	UV completions of composite Higgs models with partial compositeness
ABSTRACT: Models in which the Higgs boson is the pseudo Nambu-Goldstone boson of a strongly interacting theory represent a possible solution to the hierarchy problem; after reviewing some of the main features of such models and the usefulness of the concept of partial compositeness, it will be shown an approximately supersymmetric strongly interacting theory whose low-energy behaviour can be deduced and analyzed through the methods of Seiberg duality and whose spectrum contains both a pseudo Nambu-Goldstone boson, which can be identified with the Higgs, and partially composite Standard Model fermions.
Nov 09 2012 11:00	SISSA Santorio Building. Big Meeting Room, 7th floor.	Gianluca Blankenburg (Università degli Studi Roma 3)	U(2)^5 flavour symmetry, the lepton sector and RGE behaviour in supersymmetry
ABSTRACT: Motivated by the SUSY flavour and CP problems, the hierarchies in the Yukawa couplings and the absence so far of any direct evidence for SUSY, U(2)^3 is very promising flavour symmetry in the quark sector. We extend this framework in the lepton sector. In particular we analyze neutrino masses and Lepton Flavor Violation (LFV) in the context of supersymmetry. Neutrinos are expected to be almost degenerate, with masses close to present bounds from cosmology and neutrinoless double beta decay;. For slepton masses below 1 TeV we expect LFV within the reach of future experimental searches. We also study the behaviour of the theory under the SUSY Renormalizaton Group Equations (RGEs). In fact, even if usually the U(2)^5 symmetry is directly applied at the electroweak scale, the typical expectation is for this symmetry to be broken at a very high scale. We show if the properties of the symmetry are preserved at all scale and which are the initial conditions required to achieve the split scenario. We also study possible deviations from the minimal breaking of U(2)^5 compatible with the lepton sector.
Oct 12 2012 11:00	SISSA Santorio Building. Lecture Room 137	Diego Redigolo (Université Libre de Bruxelles & International Solvay Institute, Brussels)	Tame D-tadpoles in gauge mediation
ABSTRACT: We (arXiv:1206.7037) revisit models of gauge mediated supersymmetry breaking where messenger parity is violated. Such a symmetry is usually invoked in order to set to zero potentially dangerous hypercharge D-term tadpoles. A milder hypothesis is that the D-tadpole vanishes only at the ﬁrst order in the gauge coupling constant. Then the next order leads to a contribution to the sfermion masses which is of the same magnitude as the usual radiative one. This enlarges the parameter space of gauge mediated models. We ﬁrst give a completely general characterization of this contribution, in terms of particular three-point functions of hidden sector current multiplet operators. We then explore the parameter space by means of two simple weakly coupled models, where the D-tadpole arising at two-loops has actually a mild logarithmic divergence.
Jul 20 2012 11:00	Room 137	Alberto Parolini (SISSA)	(De)constructing a natural and flavorful supersymmetric Standard Model
ABSTRACT: I will discuss a work by Craig N., Green D. and Katz A., arXiv:1103.3708. Using the framework of deconstruction, they construct simple, weakly-coupled supersymmetric models that explain the Standard Model flavor hierarchy and produce a flavorful soft spectrum compatible with precision limits. Electroweak symmetry breaking is fully natural; the μ-term is dynamically generated with no Bμ-problem and the Higgs mass is easily raised above LEP limits without reliance on large radiative corrections. These models possess the distinctive spectrum of superpartners characteristic of “effective supersymmetry”: the third generation superpartners tend to be light, while the rest of the scalars are heavy.
Jul 13 2012 11:00	Room 137	Lorenzo Di Pietro (SISSA)	RG flow of soft masses in R-symmetric theories
ABSTRACT: The subject of the JC is 1206.3033. We will discuss the perturbation by soft supersymmetry-breaking masses of R-symmetric theories. The corresponding operator is a conserved current of the theory and its flow can be followed non-perturbatively by means of the techniques in 1109.3279 (Flavio Porri´s JC). If this operator flows to zero, the theory enjoys emergent supersymmetry in the IR, and we discuss constraints that can be put on such scenario.
Jun 29 2012 11:00	Lecture Room 137	Flavio Porri (SISSA)	A conjecture on RG flows in R-symmetric theories
ABSTRACT: In the paper 1109.3279 the author conjectured the existence of a new monotonic quantity in supersymmetric RG-flows which preserve an R-symmetry. This conjecture would provide a way to put bounds on the amount of accidental symmetries which may arise in the IR description of this kind of theories. I will introduce the definition of this quantity, show how it can be computed in some concrete examples and finally discuss its implication in the specific case of Intriligator, Seibeg and Shenker theory.
Jun 22 2012 11:00	Room 137	Vladimir Belavin (Lebedev Physical Institute, Moscow)	N = 2 superconformal blocks and instantons
ABSTRACT: We consider the problem of computing (irregular) conformal blocks in 2d CFTs whose chiral symmetry algebra is the N=2 superconformal algebra. Our construction uses two ingredients: (i) the relation between the representation theories of the N=2 rnsuperconformal algebra and the affine sl(2) algebra, extended to the level of the conformal blocks, and (ii) the relation between affine sl(2) conformal blocks and instanton partition functions in the 4d N=2 SU(2) gauge theory with a surface defect. By combining these two facts we derive combinatorial expressions for the N=2 superconformal blocks in the Gaiotto limit.
May 30 2012 16:00	Lecture Hall 128/129	Christian Hoelbling (Wuppertal)	Light quark masses and flavor physics from the lattice
ABSTRACT: I will present recent progress of lattice QCD calculations towards precision determination of light quark masses. I will describe the conceptual and technical advances that allowed recent precision determinations of the light quark masses within QCD to reach percent level accuracy with controlled systematic errors. Future challenges towards reaching sub-percent level precision are outlined. I will also briefly present some further results on light flavor physics that are relevant for checking the consistency of the standard model.
May 18 2012 11:00	Room 137	Alfredo Urbano ()	The dark side of the electroweak symmetry breaking
ABSTRACT: We show that dark matter could be a light composite scalar emerging from a TeV-scale strongly-coupled sector as a pseudo Nambu-Goldstone boson (pNGB). Such state arises naturally in scenarios where the Higgs is also a composite pNGB which are particularly predictive, since the low-energy interactions are determined by symmetry considerations. We discuss cosmological, direct and collider constraints.
Oct 07 2011 11:00	SISSA, Room 137	David Marzocca (SISSA)	The role of resonances in WW scattering in composite Higgs models
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Jun 10 2011 11:00	SISSA, room 137	Dinh Dinh (SISSA)	TBD
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May 20 2011 11:00	SISSA, room 137	Michele Del Zotto (SISSA)	D-brane physics and wall-crossing (part 2)
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May 06 2011 11:00	SISSA, room 137	Michele Del Zotto (SISSA)	D-brane physics and wall-crossing (part 1)
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Apr 19 2011 11:00	SISSA, room 137	Pietro Frè (University of Torino)	Supergravity Black Holes, Nilpotent Orbits an tensor classifiers.
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Apr 08 2011 11:00	SISSA, Room 137	Futoshi Yagi (Institut des Hautes Etudes Scientifiques)	M5-branes from ABJM model
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Mar 27 2011 11:00	SISSA, room 137	Martin Spinrath (SISSA)	Right Unitarity Triangles from Discrete Symmetries
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Mar 25 2011 11:00	SISSA, room 137	Satoshi Nawata (Tata Institute of Fundamental Research)	Localization of N=4 SCFT and Index
ABSTRACT: We provide geometric meaning of N=4 superconformal index. This allows us to interpret the N=4 index as a partition function on a twisted background. By adding $Q$-exact term, one can apply the method of localization. The partition function localizes to flat connection. The 1-loop evaluation shows that the partition function becomes a certain matrix integral as desired.
Mar 16 2011 11:00	SISSA, room 137	Leslaw Rachwal (SISSA)	Recent developments in the theory of charged particles
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Mar 14 2011 14:00	SISSA, room 137	Francesco Caracciolo (SISSA)	Stimulated Supersymmetry Breaking
ABSTRACT: It is proposed an alternative framework of SUSY breaking mediation, based on a little amount of ingredients: there exist two sectors, S and P; on one side, sector S, in isolation, would not break SUSY and would possess tree-level pseudoflat directions, radiatively lifted; on the other side, the interactions between sector S and sector P generate soft terms in S which can create a SUSY breaking vacuum at one point along a pseudoflat direction; in this situation, the strength of SUSY breaking can be many orders of magnitude greater than that of the soft terms.
Feb 25 2011 11:00	SISSA, room 137	Aurora Meroni (SISSA)	CP-Nonconserving Mechanisms of Neutrinoless Double Beta Decay
ABSTRACT: I will consider the possibility of different mechanisms contributing to the neutrinoless double beta decay amplitude in the general case of CP nonconservation: light Majorana neutrino exchange, heavy left-handed (LH) and heavy right-handed (RH) Majorana neutrino exchanges and lepton charge non-conserving couplings in SUSY theories with R-parity breaking.
Feb 18 2011 11:00	SISSA, room 137	Ryu Sasaki (Yukawa Institute, Kyoto University)	Exceptional orthogonal polynomials in Quantum Mechanics
ABSTRACT: Global solutions of Fuchsian differential equations with more than 3 (hypergeometric) or four (Heun) regular singularities had been virtually unkown. Here I present a complete set of eigenfunctions of a Schroedinger equation with $3 +¥ell$ ($¥ell=1,2,¥ldots$) regular singularities. They are obtained as the eigenfunctions of exactly solvable quantum mechanical systems.
Feb 11 2011 11:00	SISSA, room 137	Monica Guica (LPTHE Jussieu Paris)	Microscopic realization of the Kerr/CFT correspondence
ABSTRACT: Supersymmetric M/string compactifications to five dimensions contain BPS black string solutions with magnetic graviphoton charge P and near-horizon geometries which are quotients of AdS_3 x S^2. The holographic duals are typically known 2D CFTs with central charges c_L=c_R=6P^3 for large P. These same 5D compactifications also contain non-BPS but extreme Kerr-Newman black hole solutions with SU(2)_L spin J_L and electric graviphoton charge Q obeying Q^3 \leq J_L^2. It is shown that in the maximally charged limit Q^3 -> J_L^2, the near-horizon geometry coincides precisely with the right-moving temperature T_R=0 limit of the black string with magnetic charge P=J_L^{1/3}. The known dual of the latter is identified as the c_L=c_R=6J_L CFT predicted by the Kerr/CFT correspondence. Moreover, at linear order away from maximality, one finds a T_R \neq 0 quotient of the AdS_3 factor of the black string solution and the associated thermal CFT entropy reproduces the linearly sub-maximal Kerr-Newman entropy. Beyond linear order, for general Q^3
Jan 21 2011 11:00	SISSA, Room 137	Ilya Shapiro (Universidade Federal de Juiz de Fora)	One-loop form factors, multiplicative anomaly and galaxy rotation curves.
ABSTRACT: We report on some recent results on the evaluation of quantum corrections to the classical actions of gravity and electromagnetic fields. In the last case we consider the one-loop QED in curved space time and find that the effective action in the electromagnetic sector possess an ambiguity, which can be characterized as the nonlocal multiplicative anomaly. Moreover, by analyzing different space-time dimensions we come to the understanding of the real origin of this theoretical phenomenon which should probably take place also in other theories. The mentionded ambiguity may concern the exact form of the Appelquist and Carazzone theorem, but the general form of the decopuling rule remains the same. In gravity, Appelquist and Carazzone theorem can be also derived explicitly, but only for the higher derivative terms in the action. It is remarkable that the assumption of a standard quadratic decoupling for the Newton constant leads to the very good prediction for the rotation curve for a sample of nine different spiral galaxies.
Jan 14 2011 11:00		Takuya Okuda (Tokyo University)	TBD
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Dec 17 2010 11:00	SISSA, Room 137	Luca Mazzucato (Simons Center for Geometry and Physics)	Holographic dual of free field theories
ABSTRACT: We derive a holographic dual description of free quantum field theory in arbitrary dimensions, by reinterpreting the exact renormalization group, to obtain a higher spin gravity theory of the general type which had been proposed and studied as a dual theory. We show that the dual theory reproduces all correlation functions.
May 28 2010 11:30	SISSA, Room 137	Lisa Everett (University of Wisconsin, Madison)	Icosahedral Symmetry and the Standard Model Flavor Puzzle
ABSTRACT: In this talk, the possibility of using icosahedral symmetry as a family symmetry group is explored. The rotational icosahedral group, which is isomorphic to A5, the alternating group of five elements, provides a natural context in which to study (among other possibilities) the intriguing hypothesis that the solar neutrino mixing angle is governed by the golden ratio. The basic tools for flavor model-building within this framework will be described, and models of the fermion masses and mixings will be presented for both the lepton and quark sectors. The approach provides a rich setting in which to investigate the flavor puzzle of the Standard Model.
May 14 2010 11:30	SISSA, Room 137	Shahin Sheikh-Jabbari (IPM Tehran, Iran)	O-BTZ: Orientifolded BTZ Black Holes
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Apr 30 2010 11:30	SISSA, Santorio Building	Vladimir Tello (SISSA)	Left-Right Symmetry and its Phenomenological Implications
ABSTRACT: Left-right symmetric theories offer a natural connection between the smallness of neutrino mass and the scale of parity violation in weak interactions. I give here an introduction to these theories and discuss the connection between lepton number violation at colliders, neutrino-less double beta decay and lepton flavor violation. What emerges is a clear picture of the potential discovery of this theory at LHC.
Apr 23 2010 11:30	SISSA, Room 137	Luca Vecchi (LANL, Los Alamos)	The Conformal Window of deformed CFT's in the planar limit
ABSTRACT: We discuss in the planar approximation the effect of double-trace deformations on CFT?s. We show that this large class of models possesses a conformal window describing a non-trivial flow between two fixed points of the renormalization group, and reveal the presence of a resonance which we associate to the remnant of a dilaton pole. As the conformal window shrinks to zero measure the theory undergoes a conformal phase transition separating a symmetric from a nonsymmetric phase. The recently conjectured strongly coupled branch of non-supersymmetric, non-abelian gauge theories with a large number of flavors is analyzed in light of these results, and a model for the strong branch is proposed. Some phenomenological implications in the context of unparticle physics are also emphasized.
Feb 26 2010 11:30	SISSA, Room D	Jian Zhao (SISSA)	A simple introduction to localization and equivariant integration
ABSTRACT: Localization is a general principle in supersymmetric and topological field theory which has been used to treat counting problems such as counting intantons and counting curves. In this talk I will give a pedantic review on how does localization happens and how to get the equivariant integration on hyperKahler quotient space. Without much detail about ADHM construction, I want to show how to use equivariant integration to get Nekrasov's partition function.
Feb 12 2010 11:30	SISSA, Room D	Andrzej Hryczuk (SISSA)	Mirror Dark Matter
ABSTRACT: Mirror Matter is a hypothetical counterpart to ordinary matter, connected by the "mirror parity" transformation. Its existence would mean that there is a complicated dark sector with many possible phenomenological implications. In particular it provides a viable, although generally considered to be quite contrived, candidate for the dark matter. In my talk I will present the model of Mirror DM and discuss how does it fit to what we know about dark matter so far. I will also briefly discuss its direct detection and possible interpretation of DAMA results.
Jan 29 2010 11:30	SISSA, Room D	Alberto Tonero (SISSA)	Asymptotic freedom of two dimensional nonlinear sigma model
ABSTRACT: A scalar field theory in dimension d=2 is renormalizable by power counting. An example of such a theory is the so called nonlinear sigma model. It was first proposed as an alternative description of spontaneous symmetry breaking. There are some similarities between non-Abelian gauge theories in 4+e dimensions and the nonlinear sigma model in 2+e dimensions. They are both asymptotically free at e=0. In my talk I want to present the original derivation of the asymptotic freedom of the nonlinear sigma model in d=2 given by Polyakov (A.M.Polyakov, Phys. Lett. 59B, 79(1975)) and briefly discuss some alternative ways to derive the RG beta function for this model.
Jan 15 2010 11:30	SISSA, Room D	Maurizio Monaco (SISSA)	A brief introduction to little Higgs
ABSTRACT: One of the main open problems of the Standard Model is the presence of quadratically divergent quantum corrections in the Higgs mass. An interesting possibility to solve such a problem is to consider the Higgs particle as a pseudo-Nambu-Goldstone boson. In particular little Higgs theories are based on the fact that if a certain global symmetry is broken by the interplay of at least two coupling costants the Higgs mass happens to be free from quadratic divergencies at one loop. This particular kind of breaking, that is called "collective", is the essential ingredient for such a class of theories. In my talk I will give a pedagogical introduction to one of these little Higgs models, based on SU(3) symmetry group, focusing the attention on the crucial steps of the construction.
Jan 11 2010 11:30	SISSA, Room 137	Tomas Prochazka (SISSA)	Massive spin 2 field and its interaction
ABSTRACT: In this journal club I want to review some of the difficulties encountered when one tries to write down action of massive spin 2 field interacting with background metric or electromagnetic field. This is done in hep-th/0006144 and hep-th/0112182. Requirement of correct number of propagating degrees of freedom in the gravitational case leads to nontrivial restrictions on background metric and free parameters of Lagrangian. In the electromagnetic case it uniquely fixes the value of nonminimal magnetic moment coupling.
Jun 19 2009 11:00	SISSA, Room D	John Wang (Niagara University and SUNY, Buffalo (US))	Cosmology from Sbranes
ABSTRACT: We review S-brane actions derived in the context of tachyon condensation and construct a class of their cosmological solutions
Jun 05 2009 11:00	SISSA, Room D	Michael Schmidt (University of Durham)	The Hierarchy Problem in a LR Symmetric Model with Conformal Invariance
ABSTRACT: In classically conformally invariant models, a hierarchy between the Planck and the electroweak scale is naturally introduced and stabilized. However, within the Standard Model, conformal symmetry contradicts experimental data. Therefore, the Standard Model will have to be extended, if conformal symmetry ought to solve the hierarchy problem. One appealing extension is the minimal left-right symmetric model since parity is broken spontaneously and massive neutrinos are predicted. I discuss symmetry breaking in the minimal conformally invariant left-right symmetric model and demonstrate that parity is broken in a large fraction of parameter space and a > viable low energy phenomenology can be achieved.
Apr 24 2009 11:00	SISSA, Room D	Luca Di Luzio (SISSA)	The kinetic mixing in theories with several U(1) factors
ABSTRACT: After a brief description of the possible origins of U(1) factors. I will work out explicitly the renormalization of a U(1)_a \times U(1)_b unbroken theory, in order to identify those physical parameters which are needed to renormalize the theory. Among these, the kinetic mixing parameter is not generated radiatively only if some conditions on the charges are fulfilled. In the second part of the talk I will focus on low energy constraints for the kinetic mixing parameter both in the broken and unbroken case.
Mar 27 2009 13:15	SISSA, Room D	Alexander Blum (MPI, Heidelberg, Germany)	Ingredients for a flavor symmetry
ABSTRACT: Flavor symmetries are a popular method for explaining the observed regularities in the masses and the mixing of the fundamental fermions. This talk deals with the basics of such flavor symmetry models, discussing the necessary group theory and presenting simple examples.
Mar 20 2009 11:00	SISSA, Room D	Shahin Sheikh Jabbari (IPM, Tehran)	A review of the Kerr/CFT correspondence
ABSTRACT: In arXiv:0809.4266[hep-th] Strominger et.al., extending the usual AdS/CFT ideology, propose a CFT dual for an extremal 4d Kerr black hole. The proposed CFT dual in this case is a chiral half of a 2d CFT in the temperature 1/(2\pi). Using the Asymptotic Symmetry Group arguments, the central charge of this chiral CFT is also computed. Based on these considerations it is conjectured that (quantum gravity) on the (near horizon of the) extremal Kerr black hole is a chiral 2d CFT, which is, however, not specified. This correspondence has since been extended to any extremal black hole, static or stationary, in various dimensions. In this talk we review this paper and the followup papers.
Mar 06 2009 11:00	Room D	Lorenzo Seri (SISSA)	DLCQ and Plane Wave Matrix Big Bang Models
ABSTRACT: In first part I will discuss basic properties of singular homogeneous plane waves and I will explain how they arise universally as Penrose limits of space-time singularities. Then I will review the main points of the DLCQ (Dicrete Light Cone Quantization) procedure in the lightlike linear dilaton background, known as Craps-Sethe-Verlinde matrix Big Bang. My final goal is to describe how such a procedure can be generalised to singular homogeneous plane waves, and to study a few properties of the model obtained in this way.
Feb 20 2009 11:00	SISSA, Room D	Marco Nardecchia (SISSA)	The Supersymmetric Flavor Problem
ABSTRACT: I will start with a review of the flavor problem in the MSSM. I will discuss the generic mechanisms to suppress supersymmetric contributions to FCNC processes. Then I will focus on the specific case of hierarchical soft terms in which the first two generations of squarks and sleptons are heavier than the rest of the supersymmetric spectrum (arXiv:0812.3610).