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Non-perturbative aspects of chiral symmetry and confinement in QCD and related theories

English title Non-perturbative aspects of chiral symmetry and confinement in QCD and related theories
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
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All Disciplines (2)

Discipline
Theoretical Physics
Particle Physics

Keywords (13)

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

Lay Summary (English)

Lead
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

Responsible applicant and co-applicants

Employees

Publications

Publication
Acceleration of the Arnoldi method and real eigenvalues of the non-Hermitian Wilson-Dirac operator
Bergner G., Wuilloud J. (2012), Acceleration of the Arnoldi method and real eigenvalues of the non-Hermitian Wilson-Dirac operator, in Comput.Phys.Commun., 183, 299-304.
Exact results for supersymmetric quantum mechanics on the lattice
Baumgartner David, Wenger Urs (2012), Exact results for supersymmetric quantum mechanics on the lattice, in PoS, LAT2011(241), 1-7.
Lemon: an MPI parallel I/O library for data encapsulation using LIME
Deuzeman Albert, Reker Siebren, Urbach Carsten, Collaboration for the ETM (2012), Lemon: an MPI parallel I/O library for data encapsulation using LIME, in Comput.Phys.Commun., 183, 1321-1335.
On the spectrum of QCD-like theories and the conformal window
Deuzeman Albert, Lombardo Maria Paola, Pallante Elisabetta (2012), On the spectrum of QCD-like theories and the conformal window, in PoS(LAT2011), 1-7.
Bulk transitions of twelve flavor QCD and $U_A(1)$ symmetry
Deuzeman Albert, Lombardo Maria Paola, da Silva Tiago Nunes, Pallante Elisabetta (2011), Bulk transitions of twelve flavor QCD and $U_A(1)$ symmetry, in PoS(LAT2011), 1-7.
Computing K and D meson masses with $N_f$ = 2+1+1 twisted mass lattice QCD
Baron Remi, others (2011), Computing K and D meson masses with $N_f$ = 2+1+1 twisted mass lattice QCD, in Comput.Phys.Commun., 182, 299-316.
QCD at non-zero density and canonical partition functions with Wilson fermions
Alexandru Andrei, Wenger Urs (2011), QCD at non-zero density and canonical partition functions with Wilson fermions, in Phys.Rev., D83, 034502-034502.
Review of lattice results concerning low energy particle physics
Colangelo Gilberto, Durr Stephan, Juttner Andreas, Lellouch Laurent, Leutwyler Heinrich, others (2011), Review of lattice results concerning low energy particle physics, in Eur.Phys.J., C71, 1695-1695.
Simulation of supersymmetric models on the lattice without a sign problem
Baumgartner David, Wenger Urs (2011), Simulation of supersymmetric models on the lattice without a sign problem, in PoS, LAT2010, 245-245.
Spectral properties of the Wilson Dirac operator in the $��$-regime
Deuzeman Albert, Wenger Urs, Wuilloud Jair (2011), Spectral properties of the Wilson Dirac operator in the $��$-regime, in JHEP, 1112, 109-109.
Supersymmetry breaking on the lattice: the N=1 Wess-Zumino model
Baumgartner David, Steinhauer Kyle, Wenger Urs (2011), Supersymmetry breaking on the lattice: the N=1 Wess-Zumino model, in PoS, LAT2011, 253-253.
Topology, Random Matrix Theory and the spectrum of the Wilson Dirac operator
Deuzeman Albert, Wenger Urs, Wuilloud Jair (2011), Topology, Random Matrix Theory and the spectrum of the Wilson Dirac operator, in PoS, LAT2011(241), 1-7.
Chiral symmetry of QCD with twelve light flavors
Deuzeman A., Lombardo M.P., Pallante E. (2010), Chiral symmetry of QCD with twelve light flavors, in PoS, LAT2010, 123-123.
Kaon and D meson masses with N_f = 2+1+1 twisted mass lattice QCD
Baron Remi, others (2010), Kaon and D meson masses with N_f = 2+1+1 twisted mass lattice QCD, in PoS, LAT2010, 119-119.
Light hadrons from lattice QCD with light (u,d), strange and charm dynamical quarks
Baron R., Boucaud Ph., Carbonell J., Deuzeman A., Drach V., others (2010), Light hadrons from lattice QCD with light (u,d), strange and charm dynamical quarks, in JHEP, 1006, 111-111.
Light hadrons from Nf=2+1+1 dynamical twisted mass fermions
Baron R., others (2010), Light hadrons from Nf=2+1+1 dynamical twisted mass fermions, in PoS, LATTICE2010, 123-123.
Light Meson Physics from Maximally Twisted Mass Lattice QCD
Baron Remi, others (2010), Light Meson Physics from Maximally Twisted Mass Lattice QCD, in JHEP, 1008, 097-097.
Phases of QCD from small to large N(f): (Some) lattice results
Deuzeman A., Pallante E., Lombardo M.P. (2010), Phases of QCD from small to large N(f): (Some) lattice results, in Int.J.Mod.Phys., A25, 5175-5182.
Simulation of 4d N=1 supersymmetric Yang-Mills theory with Symanzik improved gauge action and stout smearing
Demmouche K., Farchioni F., Ferling A., Montvay I., Munster G., others (2010), Simulation of 4d N=1 supersymmetric Yang-Mills theory with Symanzik improved gauge action and stout smearing, in Eur.Phys.J., C69, 147-157.
The Bulk transition of many-flavour QCD and the search for a UVFP at strong coupling
Deuzeman Albert, Pallante Elisabetta, Lombardo Maria Paola (2010), The Bulk transition of many-flavour QCD and the search for a UVFP at strong coupling, in PoS, LATTICE2010, 067-067.
Twisted Mass Finite Volume Effects
Colangelo Gilberto, Wenger Urs, Wu Jackson M.S. (2010), Twisted Mass Finite Volume Effects, in Phys.Rev., D82, 034502-034502.
Worm algorithm for the O(2N) Gross-Neveu model
Maillart Vidushi, Wenger Urs (2010), Worm algorithm for the O(2N) Gross-Neveu model, in PoS, LATTICE2010, 257-257.
Efficient simulation of relativistic fermions via vertex models
Wenger Urs (2009), Efficient simulation of relativistic fermions via vertex models, in Phys.Rev., D80, 071503-071503.
First results of ETMC simulations with N(f) = 2+1+1 maximally twisted mass fermions
Baron R., Blossier B., Boucaud Philippe, Deuzeman A., Drach V., others (2009), First results of ETMC simulations with N(f) = 2+1+1 maximally twisted mass fermions, in PoS, LAT2009, 104-104.
Pseudoscalar decay constants of kaon and D-mesons from $N_f=2$ twisted mass Lattice QCD
Blossier B., others (2009), Pseudoscalar decay constants of kaon and D-mesons from $N_f=2$ twisted mass Lattice QCD, in JHEP, 0907, 043-043.
Simulating Wilson fermions without critical slowing down
Wenger Urs (2009), Simulating Wilson fermions without critical slowing down, in PoS, LAT2009, 022-022.
Simulations of supersymmetric Yang-Mills theory
Demmouche K., Farchioni F., Ferling A., Montvay I., Munster G., others (2009), Simulations of supersymmetric Yang-Mills theory, in PoS, LAT2009, 268-268.
Dynamical Twisted Mass Fermions with Light Quarks: Simulation and Analysis Details
Boucaud Philippe, others (2008), Dynamical Twisted Mass Fermions with Light Quarks: Simulation and Analysis Details, in Comput.Phys.Commun., 179, 695-715.
Iterative methods for overlap and twisted mass fermions
Chiarappa T., Jansen K., Nagai K.-I., Papinutto M., Scorzato L., others (2008), Iterative methods for overlap and twisted mass fermions, in Comput.Sci.Disc, 1(015001), 1-29.
Light baryon masses with dynamical twisted mass fermions
Alexandrou C., others (2008), Light baryon masses with dynamical twisted mass fermions, in Phys.Rev., D78, 014509-014509.
Light quark masses and pseudoscalar decay constants from N(f)=2 Lattice QCD with twisted mass fermions
Blossier B., others (2008), Light quark masses and pseudoscalar decay constants from N(f)=2 Lattice QCD with twisted mass fermions, in JHEP, 0804, 020-020.
Status of ETMC simulations with N(f) = 2+1+1 twisted mass fermions
Baron Remi, others (2008), Status of ETMC simulations with N(f) = 2+1+1 twisted mass fermions, in PoS, LATTICE2008, 094-094.

Collaboration

Group / person Country
Types of collaboration
European Twisted Mass Collaboration Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
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;


Self-organised

Title Date Place
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

Associated projects

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

Abstract

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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