Guido Altarelli

Towards small x resummed DIS phenomenology (2009)

I will present here my perception on the status of Deep Inelastic Scattering physics, as I have further developed it during this Workshop, together with a number of comments on the results that have...

Rojo, Juan, Altarelli, Guido, Ball, Richard D., Forte, Stefano

We report on recent progress towards quantitative phenomenology of small x resummation of deep-inelastic structure functions. We compute small x resummed K-factors with realistic PDFs and estimate...

Status of Neutrino Masses and Mixing in 2009 (2009)

Status of Neutrino Masses and Mixing in 2009 (2009)

We present a very concise summary of the status of our knowledge and understanding of neutrino masses and mixing.

Theoretical Models of Neutrino Mixing: Recent Developments (2009)

We present a very concise summary of the status of our knowledge and understanding of neutrino masses and mixing.

Theoretical Models of Neutrino Mixing: Recent Developments (2009)

The data on neutrino mixing are at present compatible with Tri-Bimaximal (TB) mixing. If one takes this indication seriously then the models that lead to TB mixing in first approximation are...

A Simplest A4 Model for Tri-Bimaximal Neutrino Mixing (2009)

The data on neutrino mixing are at present compatible with Tri-Bimaximal (TB) mixing. If one takes this indication seriously then the models that lead to TB mixing in first approximation are...

Altarelli, Guido, Meloni, Davide

We present a see-saw $A_4$ model for Tri-Bimaximal mixing which is based on a very economical flavour symmetry and field content and still possesses all the good features of $A_4$ models. In...

Particle Physics at the LHC Start (2009)

Particle Physics at the LHC Start (2009)

I present a concise review of where we stand in particle physics today. First, I will discuss the status of the Standard Model, its open problems and the expected answers from the LHC. Then I will...

Can we trust small x resummation? (2009)

I present a concise review of where we stand in particle physics today. First, I will discuss the status of the Standard Model, its open problems and the expected answers from the LHC. Then I will...

Forte, Stefano, Altarelli, Guido, Ball, Richard D.

We review the current status of small x resummation of evolution of parton distributions and of deep-inelastic coefficient functions. We show that the resummed perturbative expansion is stable,...

CP violation in neutrino oscillations and new physics (2008)

Altarelli, Guido, Meloni, Davide

We consider future experiments to detect CP violation in neutrino oscillations and discuss how to test that all asymmetries are indeed described in terms of the single leptonic Jarlskog invariant as...

CP violation in neutrino oscillations and new physics (2008)

Altarelli, Guido, Meloni, Davide

We consider future experiments to detect CP violation in neutrino oscillations and discuss how to test that all asymmetries are indeed described in terms of the single leptonic Jarlskog invariant as...

Structure Function Resummation in small-x QCD (2008)

Structure Function Resummation in small-x QCD (2008)

We summarize our recent results on small x resummation in full QCD with n_f quark flavours and discuss their phenomenological impact in the extraction of parton distributions from present day...

Altarelli, Guido, Ball, Richard D, Forte, Stefano

We summarize our recent results on small x resummation in full QCD with n_f quark flavours and discuss their phenomenological impact in the extraction of parton distributions from present day...

A SUSY SU(5) Grand Unified Model of Tri-Bimaximal Mixing from A4 (2008)

Altarelli, Guido, Feruglio, Ferruccio, Hagedorn, Claudia

We discuss a grand unified model based on SUSY SU(5) in extra dimensions and on the flavour group A4xU(1) which, besides reproducing tri-bimaximal mixing for neutrinos with the accuracy required by...

A SUSY SU(5) Grand Unified Model of Tri-Bimaximal Mixing from A4 (2008)

Altarelli, Guido, Feruglio, Ferruccio, Hagedorn, Claudia

We discuss a grand unified model based on SUSY SU(5) in extra dimensions and on the flavour group A4xU(1) which, besides reproducing tri-bimaximal mixing for neutrinos with the accuracy required by...

Small x Resummation with Quarks: Deep-Inelastic Scattering (2008)

A SUSY SU(5) Grand Unified Model of Tri-Bimaximal Mixing from A4 (2008)

We extend our previous results on small-x resummation in the pure Yang--Mills theory to full QCD with nf quark flavours, with a resummed two-by-two matrix of resummed quark and gluon splitting...

Altarelli, Guido, Feruglio, Ferruccio, Hagedorn, Claudia

We discuss a grand unified model based on SUSY SU(5) in extra dimensions and on the flavour group A4 x U(1) which, besides reproducing tri-bimaximal mixing for neutrinos with the accuracy required by...

Models of Neutrino Masses and Mixings (2006)

Introduction to the Terascale (2006)

We present a concise review of model building for neutrino masses and mixings, with special emphasis on recent developments.

Tri-bimaximal Neutrino Mixing from Orbifolding (2006)

We briefly review the status of the electroweak theory, in the Standard Model and beyond, on the brink of the LHC start.

Altarelli, Guido, Feruglio, F, Lin, Y

We show that the A4 discrete symmetry that naturally leads to tri-bimaximal neutrino mixing can be simply obtained as a result of an orbifolding starting from a model in 6 dimensions. This particular...

An Update on Models of Neutrino Masses and Mixings (2006)

An Update on Models of Neutrino Masses and Mixings (2006)

At the School I gave three lectures on neutrino masses and mixings. Much of the material covered in my first two lectures is written down in a review on the subject that I published not long ago with...

Tri-bimaximal Neutrino Mixing from Orbifolding (2006)

At the School I gave three lectures on neutrino masses and mixings. Much of the material covered in my first two lectures is written down in a review on the subject that I published not long ago with...

Altarelli, Guido, Feruglio, Ferruccio, Lin, Yin

We show that the A4 discrete symmetry that naturally leads to tri-bimaximal neutrino mixing can be simply obtained as a result of an orbifolding starting from a model in 6 dimensions. This particular...

The nucleon as a bound state of three quarks and deep inelastic phenomena (2006)

Altarelli, Guido, Cabibbo, Nicola, Maiani, Luciano, Petronzio, R

Introduction to renormalons (2006)

How Resummation Depresses the Gluon at Small x (2006)

Forte, S, Altarelli, Guido, Ball, R D

We summarize recent progress in the resummation of perturbative evolution at small x. We show that the problem of incorporating BFKL small x logs in GLAP evolution is now completely solved, and that...

Perturbatively Stable Resummed Small x Evolution Kernels (2005)

Perturbatively Stable Resummed Small x Evolution Kernels (2005)

We present a small x resummation for the GLAP anomalous dimension and its corresponding dual BFKL kernel, which includes all the available perturbative information and nonperturbative constraints....

Neutrino Masses with Inverse Hierarchy from Broken $L_{e}-L_{\mu}-L_{\tau}$: a Reappraisal (2005)

We present a small x resummation for the GLAP anomalous dimension and its corresponding dual BFKL kernel, which includes all the available perturbative information and nonperturbative constraints....

Altarelli, Guido, Franceschini, R

We discuss a class of models of neutrino masses and mixings with inverse hierarchy based on a broken U(1)_F flavour symmetry with charge L_e-L_\mu-L_\tau. The symmetry breaking sector receives...

Tri-Bimaximal Neutrino Mixing, A4 and the Modular Symmetry (2005)

Tri-Bimaximal Neutrino Mixing, A4 and the Modular Symmetry (2005)

We formulate and discuss a 4-dimensional SUSY version of an A4 model for tri-bimaximal neutrino mixing which is completely natural. We also study the next-to-the-leading corrections and show that...

Parton Distributions: Summary Report (2005)

We formulate and discuss a 4-dimensional SUSY version of an A4 model for tri-bimaximal neutrino mixing which is completely natural. We also study the next-to-the-leading corrections and show that...

Dittmar, M, Alekhin, S, Altarelli, Guido, Andersen, J, Ball, R D, Blümlein, J, ...

We provide an assessment of the impact of parton distributions on the determination of LHC processes, and of the accuracy with which parton distributions (PDFs) can be extracted from data, in...

The Standard Model of Particle Physics (2005)

Concluding Talk : QCD 2005 (2005)

A concise introduction to the Standard Model of fundamental particle interactions is presented.

Neutrino processes in a compound model for the nucleon (2005)

This is neither a summary talk (too much for too short a talk) nor a conclusion (a gigantic work is in progress and we are not at the end of a particular phase), rather an overview of the field as...

Altarelli, Guido, Cabibbo, Nicola, Maiani, Luciano, Petronzio, R

Deep inelastic (charged and neutral current) neutrino processes are analyzed using parton distributions obtained previously from eN inelastic reactions. Excellent agreement is found with existing...

Normal and Special Models of Neutrino Masses and Mixings (2005)

Tri-Bimaximal Neutrino Mixing from Discrete Symmetry in Extra Dimensions (2005)

One can make a distinction between "normal" and "special" models. For normal models $\theta_{23}$ is not too close to maximal and $\theta_{13}$ is not too small, typically a small power of the...

Concluding Talk: Status of the Standard Model and beyond (2005)

We discuss a particularly symmetric model of neutrino mixings where, with good accuracy, the atmospheric mixing angle theta_{23} is maximal, theta_{13}=0 and the solar angle satisfies...

Continuing CERN action on Open Access (2005)

In view of the LHC we present a concise review of the status of the Standard Model and of the models of new physics.

Continuing CERN action on Open Access (2005)

Open Access (OA) is an idea that would change the publishing landscape to bring benefits to all readers and authors. New publishing models based on electronic dissemination and OA are emerging....

Neutrino 2004: Concluding Talk (2004)

Open Access (OA) is an idea that would change the publishing landscape to bring benefits to all readers and authors. New publishing models based on electronic dissemination and OA are emerging....

Progress in the small x resummation of the singlet anomalous dimension (2004)

We review the highlights of Neutrino 2004 and recall the main lessons from neutrinos in recent years that had a great impact on particle physics and cosmology.

The Electroweak Interactions in the Standard Model and Beyond (2004)

We summarize our recent results on the small x resummation of the singlet anomalous dimension. We recall the main features of our approach, and briefly describe some work in progress on the inclusion...

Progress on Models of Neutrino Masses and Mixings (2004)

We present a concise review of the status of the Standard Model and of the models of new physics.

Models of Neutrino Masses and Mixings (2004)

We review some recent results obtained by our group on models of neutrino masses and mixings in the general context of SUSY GUT's with an associated flavour symmetry.

Precision Electroweak Tests of the Standard Model (2004)

We review theoretical ideas, problems and implications of neutrino masses and mixing angles. We give a general discussion of schemes with three light neutrinos. Several specific examples are analyzed...

Altarelli, Guido, Grünewald, M W

The study of electron-positron collisions at LEP, together with additional measurements from other experiments, in particular those at SLC and at the Tevatron, has allowed for tests of the...

Can Neutrino Mixings Arise from the Charged Lepton Sector? (2004)

Feruglio, Ferruccio, Altarelli, Guido, Masina, Isabella

The neutrino mixing matrix U is in general of the form U=U_e^+ U_nu, where U_e arises from the diagonalization of charged leptons and U_nu is from the neutrino sector. We discuss the possibility that...

An Improved Splitting Function for Small x Evolution (2003)

An anomalous dimension for small x evolution (2003)

We summarize our recent result for a splitting function for small x evolution which includes resummed small x logarithms deduced from the leading order BFKL equation with the inclusion of running...

An anomalous dimension for small x evolution (2003)

We construct an anomalous dimension for small x evolution which goes beyond standard fixed order perturbative evolution by including resummed small x logarithms deduced from the leading order BFKL...

Status of the Standard Model and Beyond (2003)

We construct an anomalous dimension for small x evolution which goes beyond standard fixed order perturbative evolution by including resummed small x logarithms deduced from the leading order BFKL...

We present a concise review of the status of the Standard Model and of the search for new physics.

A QCD Primer (2003)

Models of Neutrino Masses: Anarchy versus Hierarchy (2002)

This paper deals with the main applications of perturbative quantum chromodynamics (QCD). The paper also covers massless QCD and scale invariance, the renormalisation group and asymptotic freedom,...

Altarelli, Guido, Feruglio, Ferruccio, Masina, I

We present a quantitative study of the ability of models with different levels of hierarchy to reproduce the solar neutrino solutions, in particular the LA solution. As a flexible testing ground we...

Theoretical Models of Neutrino Masses and Mixings (2002)

Factorization and Resummation of Small x Scaling Violations with Running Coupling (2001)

We review theoretical ideas, problems and implications of different models for neutrino masses and mixing angles. We give a general discussion of schemes with three or more light neutrinos. Several...

Factorization and Resummation of Small x Scaling Violations with Running Coupling (2001)

We discuss the inclusion of running coupling effects in perturbative small x evolution equations. We show that a running coupling BFKL-like x-evolution equation is fully compatible, up to higher...

Models of neutrino masses and mixings (CERN-TH-2001-144) (2001)

We discuss the inclusion of running coupling effects in perturbative small x evolution equations. We show that a running coupling BFKL-like x-evolution equation is fully compatible, up to higher...

Indication for Light Sneutrinos and Gauginos from Precision Electroweak Data (2001)

We briefly review models of neutrino masses and mixings. In view of the existing experimental ambiguities many possibilities are still open. After an overview of the main alternative options we focus...

Altarelli, Guido, Caravaglios, F, Giudice, Gian Francesco, Gambino, Paolo, Ridolfi, G

The present Standard Model fit of precision data has a low confidence level, and is characterized by a few inconsistencies. We look for supersymmetric effects that could improve the agreement among...

Extrapolating Structure Functions to Very Small x (2001)

SU(5) Grand Unification in Extra Dimensions and Proton Decay (2001)

We review small $x$ contributions to perturbative evolution equations for parton distributions, and their resummation. We emphasize in particular the resummation technique recently developed in order...

Small-x Resummation and HERA Structure Function Data (2000)

We analyse proton decay in the context of simple supersymmetric SU(5) grand unified models with an extra compact spatial dimension described by the orbifold S^1/(Z_2 x Z_2'). Gauge and Higgs degrees...

Small-x Resummation and HERA Structure Function Data (2000)

We apply our systematic NLO small x resummation of singlet splitting functions to the scaling violations of structure functions and compare the results with data. We develop various theoretical tools...

A Summary from the Theorist's Point of View (2000)

We apply our systematic NLO small x resummation of singlet splitting functions to the scaling violations of structure functions and compare the results with data. We develop various theoretical tools...

The Standard Electroweak Theory and Beyond (2000)

1. Introduction - 2. Astrophysics and Cosmology - 3. Neutrino Oscillations - 4. Higgs and New Physics Searches - 5. Flavour Physics and CP Violation - 6. QCD - 7. Heavy Ion Collisions - 8. Outlook

The $t \to WZb$ decay in the Standard Model: A Critical Reanalysis (2000)

1. Introduction, 2. Gauge Theories, 3. The Standard Model of Electroweak Interactions, 4. The Higgs Mechanism, 5. The CKM Matrix, 6. Renormalisation and Higher Order Corrections, 7. Why we do Believe...

Altarelli, Guido, Conti, L, Lubicz, V

We compute the t->WZb decay rate, in the Standard Model, at the leading order in perturbation theory, with special attention to the effects of the finite widths of the W and Z bosons. These effects...

From Minimal to Realistic Supersymmetric SU(5) Grand Unification (2000)

Altarelli, Guido, Feruglio, Ferruccio, Masina, I

We construct and discuss a "realistic" example of SUSY SU(5) GUT model, with an additional U(1) flavour symmetry, that is not plagued by the need of large fine tunings, like those associated with...

Singlet parton evolution at small x: a theoretical update (2000)

Standard Model physics (2000)

This is an extended and pedagogically oriented version of our recent work, in which we proposed an improvement of the splitting functions at small x which overcomes the apparent problems encountered...

The crucial problem: the electroweak symmetry breaking (2000)

Introduction structure of gauge theories. The QEDand QCD examples. Chiral theories. The electroweak theory. Spontaneous symmetry breaking. The Higgs mechanism Gauge boson and fermion masses. Yukawa...

Neutrino Masses and Grand Unification (2000)

1. Why we do Believe in the Standard Model 2. Why we do not Believe in the Standard Model 2.1 Conceptual Problems 2.2 Hints from Experiment 2.2.1 Unification of Couplings 2.2.2 Dark Matter 2.2.3...

Resummation of singlet parton evolution at small x (1999)

We discuss some models of neutrino masses and mixings in the context of fermion masses in Grand Unified Theories.

Resummation of Singlet Parton Evolution at Small x (1999)

We propose an improvement of the splitting functions at small x which overcomes the apparent problems encountered by the BFKL approach. We obtain a stable expansion for the x-evolution function...

Large neutrino mixing from small quark and lepton mixings (1999)

We propose an improvement of the splitting functions at small x which overcomes the apparent problems encountered by the BFKL approach. We obtain a stable expansion for the x-evolution function...

Altarelli, Guido, Feruglio, Ferruccio, Masina, I

We discuss the special class of models where nearly maximal neutrino mixing is produced through the see-saw mechanism, starting from only nearly diagonal matrices for charged leptons, Dirac neutrinos...

Neutrino Masses and Mixings: a Theoretical Perspective (1999)

Neutrino masses: a theoretical introduction, talk (1999)

We briefly review the recent activity on neutrino masses and mixings which was prompted by the confirmation of neutrino oscillations by the Superkamiokande experiment.

A Simple Grand Unification View of Neutrino Mixing and Fermion Mass Matrices (1998)

Introduction. Neutrino oscillations. Summary of the oscillation data. Limits on neutrino masses and number of flavours. Neutrinos as possible hot dark matter. Neutrino masses and lepton number...

A Simple Grand Unification View of Neutrino Mixing and Fermion Mass Matrices (1998)

Assuming three light neutrinos and the see-saw mechanism we present a semiquantitative model of fermion masses based on (SUSY) SU(5) and abelian horizontal charges. A good description of the observed...

The Standard Electroweak Theory and Beyond (1998)

Assuming three light neutrinos and the see-saw mechanism we present a semiquantitative model of fermion masses based on (SUSY) SU(5) and abelian horizontal charges. A good description of the observed...

Models of neutrino masses from oscillations with maximal mixing (1998)

This set of lectures provides an elementary introduction to the standard electroweak theory, followed by a detailed discussion of its experimental tests. We then consider the conceptual limitations...

The Standard Model and Beyond (1998)

We discuss models of neutrino masses that lead to a large mixing angle for atmospheric neutrino oscillations. In particular we study a mechanism where a simple texture for the Dirac matrix leads to...

Are Parton Distributions Positive? (1998)

Content 1. Why we do Believe in the Standard Model 2. Why we do not Believe in the Standard Model 2.1Conceptual Problems 2.2Hints from Experiment --2.2.1 Unification of Couplings --2.2.2 Dark Matter...

Forte, Stefano, Altarelli, Guido, Ridolfi, G

We show that the naive positivity conditions on polarized parton distributions which follow from their probabilistic interpretation in the naive parton model are reproduced in perturbative QCD at the...

Neutrino Mass Textures from Oscillations with Maximal Mixing (1998)

On positivity of parton distributions (1998)

We study the implications of neutrino oscillations with maximal mixing for the neutrino Dirac and Majorana matrices in the see-saw mechanism for three non degenerate neutrino masses. We find the form...

Altarelli, Guido, Forte, Stefano, Ridolfi, G

We discuss the bounds on polarized parton distributions which follow from their definition in terms of cross section asymmetries. We spell out how the bounds obtained in the naive parton model can be...

The standard electroweak theory (1998)

Introduction. Structure of gauge theories. The QED and QCD examples. Chiral theories. The electroweak theory. Spontaneous symmetry breaking. The Higgs machanism.Gauge boson and fermion masses. Yukawa...

QCD at colliders (1998)

Theoretical Analysis of Polarized Structure Functions (1998)

Altarelli, Guido, Ball, R D, Forte, Stefano, Ridolfi, G

We review the analysis of polarized structure function data using perturbative QCD at next-to-leading order. We use the most recent experimental data to obtain updated results for polarized parton...

Electroweak Precision Tests: a Concise Review (1997)

Altarelli, Guido, Barbieri, Riccardo, Caravaglios, F

1. Introduction 2. Status of the Data 3. Precision Electroweak Data and the Standard Model 4. A More General Analysis of Electroweak Data 4.1 Basic Definitions and Results 4.2 Experimental...

The Status of the Standard Model (1997)

HERA Data and Leptoquarks in Supersymmetry (1997)

Talk given at the XVIII International Symposium on Lepton-Photon Interactions, Hamburg, 1997. 1. Introduction 2. Status of the Data 3. Precision Electroweak Data and the Standard Model 4. A More...

What can we learn from polarized structure function data? (1997)

I present a concise review of the possible evidence for new physics at HERA and of the recent work towards a theoretical interpretation of the signal. It is not clear yet if the excess observed at...

Ball, R D, Ridolfi, G, Altarelli, Guido, Forte, Stefano

We summarise the perturbative QCD analysis of the structure function data for g_1 from longitudinally polarized deep inelastic scattering from proton, deuteron and neutron targets, with particular...

Electroweak tests and new physics: a status report (1997)

What if Charged Current Events at Large $Q^2$ are Observed at HERA? (1997)

Altarelli, Guido, Giudice, Gian Francesco, Mangano, Michelangelo L

An excess of events at large Q2 with a positron in the final state has been observed at HERA which, if confirmed, would be a signal of new physics. It is not clear at present if a signal of...

Pursuing interpretations of the HERA large-$Q^{2}$ data (1997)

Altarelli, Guido, Ellis, Jonathan Richard, Lola, S, Giudice, Gian Francesco, Mangano, Michelangelo L

We explore interpretations of the anomaly observed by H1 and ZEUS at HERA in deep-inelastic e^+ p scattering at very large Q^2. We discuss the possibilities of new effective interactions and the...

Determination of the Bjorken Sum and Strong Coupling from Polarized Structure Functions (1997)

Altarelli, Guido, Ball, R D, Forte, Stefano, Ridolfi, G

We present a NLO perturbative analysis of all available data on the polarized structure function g_1(x,Q^2) with the aim of making a quantitative test of the validity of the Bjorken sum rule, of...

Status of precision tests of the Standard Model (1996)

The fate of the leptophobic Z' (1996)

The status of precision tests of the Standard Model is reviewed.

Mangano, Michelangelo L, Altarelli, Guido, Di Bartolomeo, N, Feruglio, Ferruccio, Gatto, R

We review the main features of the leptophobic-Z' phenomenology, commenting on the prospects of these models after the recent experimental results on R_c, R_b and after the recent theoretical...

Electroweak physics in and beyond the standard model (1996)

Experimental tests of the standard model and hints of new physics (1996)

Failure of local duality in inclusive non-leptonic heavy flavour decays (1996)

Altarelli, Guido, Martinelli, G, Petrarca, S, Rapuano, F

We argue that there is strong experimental evidence in the data of b- and c-decays that the pattern of power suppressed corrections predicted by the short distance expansion, the heavy quark...

R$_{b}$, R$_{c}$ and jet distributions at the Tevatron in a model with an extra vector boson (1996)

Altarelli, Guido, Di Bartolomeo, N, Feruglio, Ferruccio, Gatto, R, Mangano, Michelangelo L

We show that the reported anomalies in R_b and R_c can be interpreted as the effect of a heavy vector boson V universally coupled to u- and d-type quarks separately and nearly decoupled from leptons....

The pion structure function in a constituent model (1995)

Altarelli, Guido, Petrarca, S, Rapuano, F

Using the recent relatively precise experimental results on the pion structure function, obtained from Drell--Yan processes, we quantitatively test an old model where the structure function of any...

The QED running coupling and DA$\phi$NE (1995)

Interim report on the physics motivations for an energy upgrade of LEP2 (1995)

The epsilon variables for electroweak precision tests: a reappraisal (1995)

Altarelli, Guido, Barbieri, Riccardo, Caravaglios, F

A study of ultraviolet renormalon ambiguities in the determination of $\alpha_{s}$ from $\tau$ decay (1995)

Altarelli, Guido, Nason, P, Ridolfi, G

The divergent large-order behaviour of the perturbative series relevant for the determination of \as from \tau decay is controlled by the leading ultraviolet (UV) renormalon. Even in the absence of...

$\alpha_{s}$ from $\tau: ba discussion of theoretical errors (1994)

Electroweak precision tests: a status report (1994)

Lower limit on the Higgs mass in the Standard Model: an update (1994)

Altarelli, Guido, Isidori, Gino

Status of precision tests of the electroweak theory (1994)

Neutrino masses: a theoretical introduction (1994)

The standard electroweak theory and its experimental tests (1994)