## Contact

Swiss National Science Foundation (SNSF)

Wildhainweg 3P.O. Box

CH-3001 Bern

Phone +41 31 308 22 22

English title | Non-perturbative aspects of chiral symmetry and confinement in QCD and related theories |
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Applicant | Wenger Urs Rudolf |

Number | 119015 |

Funding scheme | SNSF Professorships |

Research institution | Institut für Theoretische Physik Universität Bern |

Institution of higher education | University of Berne - BE |

Main discipline | Theoretical Physics |

Start/End | 01.03.2008 - 29.02.2012 |

Approved amount | 1'532'551.00 |

Discipline |
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Theoretical Physics |

Particle Physics |

Particle Physics; Theoretical Physics; Large-N Gauge Theories; Numerical Simulations; Lattice Gauge Theory; Confinement; Non-Perturbative Calculations; Algorithms; Supersymmetric Gauge Theories; Lattice QCD; Chiral Symmetry; String-Gauge Duality; Supersymmetric matrix models

Lead |
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Lay summary |

At low energies, Quantum Chromodynamics (QCD) exhibits a variety of phenomena that can not be described in the framework of perturbation theory. Many of these non-perturbative aspects of the theory are still poorly understood, like for example colour confinement, the fact that only composite colour-neutral particles, so-called hadrons, can be observed in nature, but not the quarks and gluons themselves. Another non-perturbative aspect of QCD is the spontaneous breaking of chiral symmetry leading to the particular spectrum of the lightest hadrons observed in nature. Yet another striking non-perturbative phenomenon is the restoration of chiral symmetry, either at large density where new unexplored phases of baryonic matter emerge, as they might exist in compact stars, or at high temperature where ordinary hadronic matter transforms into a quark-gluon-plasma, as is beautifully demonstrated by lattice QCD calculations and also indicated by heavy-ion collision experiments.It is clear that a thorough qualitative and quantitative understanding of all these non-perturbative aspects of QCD is of utmost importance for the justification of QCD as the fundamental theory describing the strong interactions and for the justification of the Standard Model (SM) in general.One goal of this project is to provide exactly such an understanding of low-energy QCD via computer simulations where all the systematic errors are under control. Precise ab-initio calculations of the non-perturbative properties of QCD in the chiral regime will enable a further confirmation of the theoretical framework. One of the main challenges for non-perturbative QCD calculations lies e.g.~in the accurate and reliable determination of hadronic matrix elements and form factors which in many cases constitute the main source of theoretical uncertainties in the direct confrontation of the theory with experiment. Furthermore, such results will be used as valuable input into non-perturbative effects in SM phenomenology, and beyond, via the reduction of theoretical uncertainties in the hadronic sector. This will provide stringent tests of the SM and constitute an invaluable contribution towards the potential discovery of new Beyond the Standard Model (BSM) physics at the Large Hadron Collider (LHC).In the same spirit this project also aims to put the non-perturbative study of QCD and QCD-like theories to wider use beyond the SM. This is achieved by trying to derive analogous non-perturbative properties of large-N field theories, where the number of colour degrees of freedom is taken to infinity, or Supersymmetric (SUSY) gauge theories that are likely to turn out to be the more fundamental theories in Particle Physics. This approach is made possible on the one hand through our recent developments in understanding and simulating QCD and related theories in the chiral regime, but also through our novel, non-perturbative studies of (pure gauge) QCD in the limit of a large number of quark colours. In particular, the large-N limit allows to build a bridge between the conventional Quantum Field Theory approach to particle physics and alternative theories like string theories which try to explain our microscopic world as the result of resonating strings and branes. Another important step is our recent development of the fermion loop formulation for low-dimensional SUSY models on the lattice, e.g. SUSY matrix models. This allows very efficient simulations of these models and hence the non-perturbative investigation of spontaneous SUSY breaking from first principles. The understanding of the non-perturbative properties related to confinement, chiral symmetry and SUSY breaking of large-N and SUSY field theories will lead to new insights into the mechanisms and theories behind it. To gain a non-perturbative understanding of these theories is one of the main objectives of this proposal and will be of highest relevance in view of the potential discovery of BSM physics at the LHC. |

Direct link to Lay Summary | Last update: 21.02.2013 |

Name | Institute |
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Publication |
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Acceleration of the Arnoldi method and real eigenvalues of the non-Hermitian Wilson-Dirac operator |

Exact results for supersymmetric quantum mechanics on the lattice |

Lemon: an MPI parallel I/O library for data encapsulation using LIME |

On the spectrum of QCD-like theories and the conformal window |

Bulk transitions of twelve flavor QCD and $U_A(1)$ symmetry |

Computing K and D meson masses with $N_f$ = 2+1+1 twisted mass lattice QCD |

QCD at non-zero density and canonical partition functions with Wilson fermions |

Review of lattice results concerning low energy particle physics |

Simulation of supersymmetric models on the lattice without a sign problem |

Spectral properties of the Wilson Dirac operator in the $��$-regime |

Supersymmetry breaking on the lattice: the N=1 Wess-Zumino model |

Topology, Random Matrix Theory and the spectrum of the Wilson Dirac operator |

Chiral symmetry of QCD with twelve light flavors |

Kaon and D meson masses with N_f = 2+1+1 twisted mass lattice QCD |

Light hadrons from lattice QCD with light (u,d), strange and charm dynamical quarks |

Light hadrons from Nf=2+1+1 dynamical twisted mass fermions |

Light Meson Physics from Maximally Twisted Mass Lattice QCD |

Phases of QCD from small to large N(f): (Some) lattice results |

Simulation of 4d N=1 supersymmetric Yang-Mills theory with Symanzik improved gauge action and stout smearing |

The Bulk transition of many-flavour QCD and the search for a UVFP at strong coupling |

Twisted Mass Finite Volume Effects |

Worm algorithm for the O(2N) Gross-Neveu model |

Efficient simulation of relativistic fermions via vertex models |

First results of ETMC simulations with N(f) = 2+1+1 maximally twisted mass fermions |

Pseudoscalar decay constants of kaon and D-mesons from $N_f=2$ twisted mass Lattice QCD |

Simulating Wilson fermions without critical slowing down |

Simulations of supersymmetric Yang-Mills theory |

Dynamical Twisted Mass Fermions with Light Quarks: Simulation and Analysis Details |

Iterative methods for overlap and twisted mass fermions |

Light baryon masses with dynamical twisted mass fermions |

Light quark masses and pseudoscalar decay constants from N(f)=2 Lattice QCD with twisted mass fermions |

Status of ETMC simulations with N(f) = 2+1+1 twisted mass fermions |

Group / person | Country |
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Types of collaboration |
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European Twisted Mass Collaboration | Germany (Europe) |

- in-depth/constructive exchanges on approaches, methods or results - Publication - Research Infrastructure - Exchange of personnel |

Title | Type of contribution | Title of article or contribution | Date | Place | Persons involved |
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Workshop on Chiral dynamics with Wilson fermions | Talk given at a conference | Supersymmetry on the lattice with Wilson fermions | 24.10.2011 | Trento, Italien, Italy | Wenger Urs Rudolf; |

The XXIX International Symposium on Lattice Field Theory | Talk given at a conference | Supersymmetry on the lattice: the N = 1 Wess-Zumino model | 10.07.2011 | Squaw Valley, Lake Tahoe, CA, USA, United States of America | Wenger Urs Rudolf; Deuzeman Albert; Baumgartner David; |

European Twisted Mass Collaboration (ETMC) Meeting | Individual talk | TopologyforNf =2+1+1 | 15.09.2010 | Barcelona, Spanien, Spain | Wenger Urs Rudolf; |

CERN Workshop Future Directions in Lattice Gauge Theories (LGT10) | Talk given at a conference | Loop formulation of supersymmetric models on the lattice | 04.08.2010 | Genf, Schweiz, Switzerland | Wenger Urs Rudolf; |

The XXVIII International Symposium on Lattice Field Theory | Talk given at a conference | Loop gas formulation of low dimensional SUSY models | 14.06.2010 | Villasimius, Sardinien, Italien, Italy | Wenger Urs Rudolf; Baumgartner David; |

European Twisted Mass Collaboration (ETMC) Meeting | Individual talk | Twisted Mass Finite Volume Effects | 29.03.2010 | Bonn, Deutschland, Germany | Wenger Urs Rudolf; Deuzeman Albert; |

7th Workshop on QCD in Extreme Conditions (XQCD 2009) | Talk given at a conference | On the relevance of the sign problem in supersymmetric models | 03.08.2009 | Seoul, Korea, Korean Republic (South Korea) | Wenger Urs Rudolf; |

The XXVII International Symposium on Lattice Field Theory | Talk given at a conference | Simulating Wilson fermions without critical slowing down | 26.07.2009 | Beijing, China, China | Wenger Urs Rudolf; Deuzeman Albert; |

European Twisted Mass Collaboration (ETMC) Meeting | Talk given at a conference | Topology for twisted mass fermions | 18.03.2009 | Autrans, Frankreich, France | Wenger Urs Rudolf; |

International Workshop on Sign Problems and Complex Actions | Talk given at a conference | Solution of a sign problem by explicit bosonisation | 02.03.2009 | Trento, Italien, Italy | Wenger Urs Rudolf; |

International Workshop on Frontier Problems in Strong Interactions Physics | Talk given at a conference | The phase diagram of QCD at finite isospin density | 12.02.2009 | Bangalore, Indien, India | Wenger Urs Rudolf; |

5th Workshop on Numerical Analysis and Latice QCD (QCDNA 2008) | Talk given at a conference | From fermions to loop and dimer models | 03.09.2008 | Regensburg, Deutschland, Germany | Wenger Urs Rudolf; |

6th Workshop on QCD in Extreme Conditions (XQCD 2008) | Talk given at a conference | From fermions to loop and dimer models | 19.07.2008 | Raleigh, USA, United States of America | Wenger Urs Rudolf; |

The XXVI International Symposium on Lattice Field Theory | Talk given at a conference | Topological susceptibility from lattice QCD | 13.07.2008 | Williamsburg, USA, United States of America | Wenger Urs Rudolf; |

International Workshop on Lattice Field Theory and Statistical Physics (LEILAT08) | Talk given at a conference | From fermions to loop and dimer models | 25.06.2008 | Leipzig, Deutschland, Germany | Wenger Urs Rudolf; |

European Twisted Mass Collaboration (ETMC) Meeting | Talk given at a conference | Topological susceptibility from lattice QCD | 09.05.2008 | Trento, Italien, Italy | Wenger Urs Rudolf; |

Title | Date | Place |
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European Twisted Mass Collaboration (ETMC) Meeting | 23.03.2011 | Bern, Schweiz, Switzerland |

FLAVIAnet School on Flavour Physics | 21.06.2010 | Bern, Schweiz, Switzerland |

6th International Workshop on Chiral Dynamics | 06.07.2009 | Bern, Schweiz, Switzerland |

International Workshop on Perspectives and Challenges for full QCD Lattice Calculations | 05.05.2008 | Trento, Italien, Italy |

Number | Title | Start | Funding scheme |
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139196 | Non-perturbative aspects of chiral symmetry and confinement in QCD and related theories | 01.03.2012 | SNSF Professorships |

The primary goal of this project is to provide a thorough qualitative and quantitative understanding of non-perturbative phenomena in the chiral regime of Quantum Chromodynamics (QCD) and related models via computer simulations. Many of these non-perturbative aspects are still poorly understood, like for example colour confinement, or the spontaneous breaking of chiral symmetry and its restoration either at high temperature or at large chemical potential where new and partly unexplored phases of strongly interacting matter emerge.One of the main challenges for non-perturbative QCD calculations lies in the accurate and reliable determination of the hadronic properties which in many cases constitute the main source of theoretical uncertainties in the direct confrontation of the theory with experiment. The precise ab-initio calculations that we are proposing in this project will enable a further confirmation of the theoretical framework and provide stringent tests of the Standard Model (SM). Moreover they will constitute invaluable contributions towards the potential discovery of new physics beyond the SM at the Large Hadron Collider (LHC).In the same spirit we also aim to put the non-perturbative study of QCD and QCD-like theories to wider use beyond the SM. This is achieved by our proposal to derive analogous non-perturbative properties of supersymmetric gauge theories that are likely to turn out to be the more fundamental theories in Particle Physics. This approach is made possible on the one hand through our recent developments in understanding and simulating QCD and related theories in the chiral regime, but also through our novel, non-perturbative studies of (pure gauge) QCD in the limit of a large number of quark colours. In particular, our proposed calculations allow to build a bridge between the conventional Quantum Field Theory approach and alternatives like string theories which try to explain our microscopic world as the result of resonating strings and branes. The understanding of the non-perturbative properties related to confinement and chiral symmetry breaking of large-N and SUSY field theories will lead to new insights into the fundamental mechanisms and theories behind it. To gain a non-perturbative understanding of these theories is one of the main objectives of this proposal and will be of highest relevance in view of the potential discovery of BSM physics at the LHC.

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Wildhainweg 3P.O. Box

CH-3001 Bern

Phone +41 31 308 22 22

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