Theory Group Seminars INFN Rome I & INFN Rome III, 2006 - 2007

Next Seminars:

Friday, November 3rd, 2006, 15:00, Aula M. Conversi, Roma1
D. Lyth (Lancaster University, UK)
Title: Primordial non-gaussianity
Abstract: Non-gaussianity of the primordial curvature will probably be observed eventually, if and only if the perturbation is generated after inflation. A user-friendly description of this state of affairs will be presented, based on the powerful and intuitive $\delta N$ formalism.

Thursday, November 9th, 2006, 15:00, Aula M. Conversi, Roma1
J. Carbonell (LPSC, Grenoble, France)
Title: Some new results with Bethe-Salpeter and Light-Front equations
Abstract: A new method, developed for solving Bethe-Salpeter (BS) equation in Minkowski space, will be presented. It is based on projecting the BS equation on the Light-Front (LF) plane and the Nakanishi integral representation of the BS amplitude. This method, valid for any kernel given by the irreducible Feynman graphs, has been applied for solving BS equation with a kernel containing ladder + cross-ladder exchanges, within a purely scalar model. It will be discussed in detail the effects of the two kernel contributions and the solution for the corresponding LF equation, showing that both approaches, BS and LF, yield very close results. The consequences of using the BS amplitude in Euclidean space for calculating form factors will be discussed. First results in solving the full quantum field contents of the Yukawa model using lattice techniques will be presented.

Thursday, November 16th, 2006, 15:00, Aula M. Conversi, Roma1
V. Lubicz (Roma III and INFN)
Title: Lattice QCD confronts the Unitarity Triangle Fit
Abstract: We discuss the role of lattice QCD calculations in the Unitarity Triangle Analysis. We show, in particular, how the recent measurement of Deltams allows for an "experimental" determination of the hadronic parameters relevant for B-Bbar and K-Kbar mixing, the result of which can be compared with the theoretical predictions from lattice QCD. We also discuss the different determinations of Vub and show that current data do not favor the value measured in inclusive decays. Finally, we present updated predictions for the leptonic branching fraction BR(B -> tau nu), and compare them with the recent experimental determination.

Thursday, November 30th, 2006, 15:00, Aula Conversi, Roma1
F. Vissani (INFN - LNGS)
Title: TBA
Abstract:

Tuesday, December 5th, 2006, 16:00, Aula Conversi, Roma1
R. Barbieri (Scuola Normale Superiore)
Title: Particelle elementary e "fisica fondamentale"
Abstract:

Thursday, December 7th, 2006, 15:00, Aula ??, Roma1
M. Salvatori (Univ. Autonoma, Madrid)
Title: TBA
Abstract:

Thursday, December 21st, 2006, 15:00, Aula ??, Roma1
L. Reina (Florida State Univ., USA)
Title: Higgs boson production with heavy quarks at hadron colliders
Abstract:


Previous Seminars:


Friday, October 13th, 2006, 15:00, Aula M. Conversi, Roma1
M. Neubert (Cornell University, USA)
Title: Collider Physics using Effective Field Theory
Abstract: Methods from soft-collinear effective theory provide a new perspective on some old problems in collider physics, such as collinear factorization, scale separation and resummation of large logarithms. We discuss the resummation of Sudakov logarithms in the threshold region for deep inelastic scattering, Drell-Yan production and Higgs production directly in momentum space. Our approach avoids the cumbersome detour through Mellin moment space, which is known to be plagued by Landau poles. Contributions associated with different physical scales are separated from non-perturbative hadronic physics in a transparent way.

Thursday, October 12th, 2006, 17:00, Aula M. Conversi, Roma1
C. Martins (University of Cambridge, UK)
Title: From $\alpha$ to $w$: Astrophysical Probes of Fundamental Physics
Abstract: I will review the theoretical motivation for varying fundamental couplings, present some recent results, and discuss how these measurements can be used to constrain a number of fundamental physics scenarios that would otherwise be inacessible to experiment. As a case study I will focus on the relation between varying couplings and dark energy, and explain how varying coupling measurements can be used to probe the nature of dark energy, through a reconstruction of its equation of state, with some advantages over the standard methods.

Thursday, September 28th, 2006, 15:00, Aula F.Rasetti, Roma1
S. Davidson (University of Lyon, France)
Title: Flavour Matters in Leptogenesis
Abstract: Thermal leptogenesis is an attractive mechanism to generate the matter we are made of. In the hot early Universe, a lepton asymmetry is produced by the interactions of a very heavy M ~109 GeV singlet neutrino, and then reprocessed, by non-perturbative Standard Model interactions, into a baryon asymmetry. The dynamics of producing an asymmetry in total lepton number has been carefully studied in the past. I will argue that it is important to follow the evolution of the three flavoured lepton asymmetries. This generically enhances the predicted baryon asymmetry, because more CP violation is allowed and washout is reduced. The "leptogenesis bound" on the light neutrino mass scale disappears.

Thursday, July 6th, 2006, 15:00, Aula Conversi, Roma1
C. Csaki (Cornell University)
Title: The super-little Higgs
Abstract: The non-discovery of superpartners at LEP2 and the Tevatron imply that if superpartners exist they have to be quite a bit heavier than the Z-mass leading to the little hierarchy problem of supersymmetry. A simple idea for resolving this issue would be if the Higgs (in addition to being supersymmetric) would also be a pseudo-Goldstone boson of a global symmetry broken at a scale not much above the TeV scale. Here we examine whether this idea can be implemented in a simple way. We show what the inherent difficulties are with such setups and what kind of theories could overcome them. We discuss some of the phennomenological consequences of the model considered in detail.
Wednesday, May 24th, 2006, 15:00, Aula VN4, Roma3
A. Sirlin (NYU)
Title: Universality of Weak Interactions

Thursday, May 4th, 2006, 15:00, Aula Conversi, Roma1
L. Giusti (CERN)
Title: Lattice QCD with light quarks confronts chiral perturbation theory
Abstract: After a brief introduction on the lattice QCD technique, I present first results from full QCD simulations carried out with Wilson fermions at pion masses as low as 280 MeV and lattice spacings a=0.06-0.08~fm. A detailed comparison of pion masses and decay constants with the predictions of chiral perturbation theory is presented. The impact of this technique on the determinations of weak matrix elements relevant to flavor physics is discussed.
Monday, September 19th, 2005, 15:00, Aula Conversi, Roma1
A. De Rujula (CERN, Geneva)
Title: A Theory of Cosmic Rays: arguably, the oldest mystery of High-Energy Physics
Abstract: I shall present a theory of cosmic rays (CRs) based on a single acceleration mechanism at all relativistic energies. The distribution of CRs in the Galaxy, their total luminosity, the broken power-law spectra with their observed slopes, the position of the "Knee(s)" and "Ankle", and the CR composition and its variation with energy are all predicted in terms of very simple and completely "standard" physics. The theory is very predictive: only two parameters specific to CRs have to be fit to the data, all other inputs are "priors", that is, theoretical or observational items of information independent of CR data.
Thursday, September 29th, 2005, 15:00, Aula Majorana, Roma1
F.L. Gross (Th. Jefferson Natl. Lab.)
Title: Calculation of Bound State and Self-Energy from Field Theory
Abstract: The Feynman-Schwinger Representation (FSR), an alternative to lattice gauge theory, also uses path integrals to obtain an exact numerical solution to nonperturbative problems. The method leads to a particularly convenient way to test the quality of commonly used approximations in field theory. Exact calculations for scalar theories in quenched FSR will be presented for one-, two-, and three-body systems and the results compared to some commonly used approximations, such as Bethe-Salpeter ladder summation for two-body bound states and the rainbow summation for the one-body self energy. Some unexpected conclusions emerge from the comparison.
Thursday, October 6th, 2005, 16:30, Aula Conversi, Roma1
Riunione del gruppo per stabilire la lista degli speakers 2005-2006

Thursday, October 13th, 2005, 15:00, Aula Conversi, Roma1
A. Melchiorri (Roma)
Title:Constraints on neutrino Physics from cosmology and their impact on world neutrino data
Abstract: We demonstrate that Cosmic Microwave Background anisotropies and galaxy clustering data yield an indication for primordial anisotropies in the cosmological Neutrino Background. We then derive several cosmological bounds on Neutrino Physics. The results are discussed and compared with neutrino oscillation data and upper limits on the effective neutrino mass from beta decay experiments.
Thursday, October 20th, 2005, 15:00, Aula Majorana, Roma1
E. Gabrielli (Helsinki)
Title: Light Mesons and Muon Radiative Decays and Photon Polarization Asymmetry
Abstract: I will review the main results regarding light mesons and muon radiative decays, considering both final lepton and photon polarizations. The undergoing dynamics giving rise to lepton and photon polarization will be examined in the soft and hard region of momenta. A particular attention will be devoted to the analysis of the photon polarization asymmetry, a sensitive tool for precise measurements of hadronic form factors in radiative meson decay. Finiteness of polarized amplitudes against infrared and collinear singularities is shown to take place with mechanisms distinguishing between right-handed and left-handed final leptons. Finally, a possible test using photon polarization will be proposed in order to clarify a recently observed discrepancy in radiative pion decay.
Thursday, October 27th, 2005, 15:00, Aula Conversi, Roma1
L.J. Dixon (SLAC)
Title: Twistor Spinoffs for Collider Physics
Abstract: The search for physics beyond the Standard Model at high-energy particle colliders requires a thorough understanding of new physics signals and Standard Model background processes. Large numbers of complicated Feynman diagrams with many quarks and gluons have to be summed up, in order to predict event rates accurately. In the past two years, spinoffs from "twistor string theory" have led to very efficient alternatives to Feynman diagrams for computing many of these scattering amplitudes, first at the tree level, and now at the loop level. In this talk, I will give an overview of the recent progress.
Thursday, November 24th, 2005, 15:00, Aula G, Roma3
V. Cirigliano (Caltech)
Title: Minimal Lepton Flavour Violation
Abstract: I discuss the notion of minimal flavor violation in the lepton sector and its realizations. Minimal lepton flavor violation allows one to express lepton flavor violation in the charged sector in terms of neutrino masses and mixing angles. I discuss phenomenological implications for processes such as \mu->e \gamma, \mu to e conversion, \tau->\mu gamma.
Wednesday, March 15th, 2006, 14:00, Aula Conversi, Roma1
A. Soddu (Weizmann Institute, Israele)
Title: Four generation phenomenology
Abstract: Recent works have shown that a sequential extra generation is allowed from electroweak precision measurements if the fourth heavy neutrino is highly decoupled from the three light ones. A fourth sequential generation can have important phenomenological implications in the quark sector. For the lepton sector we show that the eV-seesaw can be incorporated in a four generation scenario and in particular we give a solution for all oscillation data (including LSND) for both the case of three and four generations.


Seminars Rome I, 2000-2001
Joint Seminars Rome I - Rome III, 2001-2002
Joint Seminars Rome I - Rome III, 2002-2003
Joint Seminars Rome I - Rome III, 2003-2004

  • The Seminar Schedule of the University of Rome "Tor Vergata" can be found at this url .
  • The Seminars Schedule of the Physics Department of Rome III can be found at this url .
  • The Seminar Schedule of the Laboratori Nazionali di Frascati (LNF) can be found at this url .


  • Instructions on how to reach the Physics Department of the University of Rome "La Sapienza" and INFN Rome I can be found at this url .
  • Instructions on how to reach the Physics Department of the University of Rome "Tor Vergata" and INFN Rome II can be found at this url .
  • Instructions on how to reach the Physics Department of the University of Rome3 and INFN Rome III can be found at this url .


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