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Dynamical QuarksPushan Majumdar in Graz (2003-2005)
C.B.Lang, Univ. Graz
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Pushan
• 2001-2003 München: Strings
• 2003-2005 Graz (Lise-Meitner-Fellow):
• from quenched to dynamical quarks, a basis for hadron
properties calculations
• 2005-2007 Münster
• 2007 Kolkata
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Pushan in Graz
Stefano Capitani, Pushan Majumdar, Leonid Glozman, Christian
Lang
Phillip Huber, Wolfgang Ortner
Meeting of the Lattice group (2005)
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Publications with Pushan
The condensate for two dynamical chirally improved quarks in
QCD; C. B. Lang, Pushan Majumdar, and Wolfgang Ortner. Phys. Lett.
B 649 (2007) 225;
Dirac Eigenmodes in an Environment of Dynamical Fermions; C. B.
Lang, Pushan Majumdar and Wolfgang Ortner . in: "Sense of beauty in
physics: a volume in honor of Adriano Di Giacomo", Ed. A. D'Elia et
al., Pisa Univ. Press (2006);
QCD with two dynamical flavors of chirally improved quarks; C.
B. Lang, Pushan Majumdar and Wolfgang Ortner. Phys. Rev. D 73
(2006) 034507.
First results from dynamical chirally improved fermions;
Christian B. Lang, Pushan Majumdar, and Wolfgang Ortner.
PoS(LAT2005)131
Implementing Hybrid Monte Carlo with stout-smeared chirally
improved Dirac operators; Christian B. Lang, Pushan Majumdar, and
Wolfgang Ortner. PoS(LAT2005)124
• Dynamical quarks • Chirally improved
• 2001-2003 München
• 2003-2005 Graz (Lise-Meitner-Fellow):
• 2005-2007 Münster
• 2007 Kolkata
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Gluons and quarks
= ∫ d[U]∫ d[ψ, ψ̄]e−Sg(U)−ψ̄Dψρ(t)ρ(0)⟨ρ(t)ρ(0)⟩
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Gluons and quarks
= ∫ d[U]∫ d[ψ, ψ̄]e−Sg(U)−ψ̄Dψρ(t)ρ(0)
= ∫ d[U]e−Sg(U) det Du det Dd (D−1u D−1d …)
≈ ∑U
det Du det Dd (D−1u D−1d …)
⟨ρ(t)ρ(0)⟩
sea quarks valence quarks
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“Quenched” quarks
Euclideant
Femtouniverse
3-5fm= ∫ d[U]∫ d[ψ, ψ̄]e−Sg(U)−ψ̄Dψρ(t)ρ(0)
= ∫ d[U]e−Sg(U) det Du det Dd (D−1u D−1d …)
≈ ∑U
det Du det Dd (D−1u D−1d …)
⟨ρ(t)ρ(0)⟩
sea quarks valence quarks
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Dynamical quarks - “full QCD”
Euclideant
Femtouniverse
3-5fm= ∫ d[U]∫ d[ψ, ψ̄]e−Sg(U)−ψ̄Dψρ(t)ρ(0)
= ∫ d[U]e−Sg(U) det Du det Dd (D−1u D−1d …)
≈ ∑U
det Du det Dd (D−1u D−1d …)
⟨ρ(t)ρ(0)⟩
sea quarks valence quarks
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Chiral symmetry
The QCD Dirac action for massless quarks has chiral symmetry
SU(2)L × SU(2)R
The QCD interaction spontaneously breaks this symmetry, thus
⟨ψ̄ψ⟩ ≠ 0
Therefore there is a Goldstone boson: the pion
The Wilson lattice action has no chiral symmetry.
Dci2428 terms
(hard)
“Chirally Improved”
DWilson8 terms
(simple)
no chiral symmetry
Doverlapneeds rational
or pol. approximation
(extremely hard)
chiral symmetryGattringer, PRD 63, 114501 (2001).
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Implementing the CI action
Hybrid Monte Carlo algorithm, technically highly demanding
Provided the basis for many subsequent projects:
Eigenspectrum of the Dirac operator
QCD condensate
Hadron masses
Hadron structure
Excited states
gauge configurations {U}
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Pushan’s Topics
#1 Heavy Quark Momentum Diffusion Coefficient from Lattice QCD
(133 citations)#2 Susceptibilities and screening masses in two
flavor QCD (110 citations)#3 The String spectrum from large Wilson
loops (44 citations)#4 The Condensate for two dynamical chirally
improved quarks in QCD (37 citations)#5 Charm and strange hadron
spectra from overlap fermions on HISQ gauge configurations(33
citations)#6 Static potential, force, and flux tube profile in 4-D
compact U(1) lattice gauge theory with the multilevel algorithm(32
citations)#7 QCD with two dynamical flavors of chirally improved
quarks (31 citations)#8 String-like behaviour of 4-D SU(3)
Yang-Mills flux (30 citations)#9 Continuum limit of string
formation in 3-d SU(2) LGT (25 citations)#10 Continuum limit of the
spectrum of the hadronic string (23 citations)
■ Topic: QCD ■ Topic: String
■ Papers written in Graz
ordered according to #citations
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Reference letter (2007)
…Pushan was a driving force and a most active contributor,…
I consider Dr. Majumdar an experienced theoretical physicist,
highly motivated and talented. He recognizes and solves problems,
both with excellent analytical understanding but also with
expertise in programming. […] Within our group he has been leading
our recent research activities involving dynamical chiral fermions
[…] He has helped considerably in advising our groups students, in
particular the doctoral students. He participates lively and
profoundly in discussions and gives well-prepared talks and
lectures.
Dr. Majumdar is highly qualified, has an easy-to-talk-to, open
minded and friendly personality.[ …]
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Wonderful days.
Do not cry that they are over.
Smile that they have been.
Pushan Majumdar
July 2005 in Trento, Italy
