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Stuart Samuel (physicist)

December 15, 2023

Stuart Samuel is a theoretical physicist known for his work[1] on the speed of gravity and for his work[2] with Alan Kostelecký on spontaneous Lorentz violation in string theory, now called the Bumblebee model. He also made significant contributions in field theory and particle physics.

Samuel graduated from Princeton University with a Bachelor of Arts in mathematics in 1975, and in 1979, he graduated from the UC Berkeley, with a Doctor of Philosophy in physics. He was formerly a member of the Institute for Advanced Study at Princeton, a professor of physics at Columbia University, and a professor of physics at City College of New York.

Earlier work edit

In early work, Samuel used particle field theory methods to obtain results in statistical mechanics.[3][4][5][6] In particular, Samuel uncovered a particularly simple way to solve the two-dimensional Ising model. It was shown to be equivalent to a non-interacting field theory of fermionic-like particles. This allowed a rapid computation of the partition function[4] and correlation functions.[5] Samuel went on to treat certain interacting statistical mechanics systems using perturbative field theory.[6]

Scalar lattice QCD edit

In 1985, Samuel and co-worker K.J.M. Moriarty were among the first to obtain a reasonably accurate computation of the hadron mass spectrum using computer simulations of lattice quantum chromodynamics (QCD). They overcame the difficulties that other theorists were encountering at the time by making an approximation: They replaced the spin 1/2, fermionic quarks with spin zero scalar particles and corrected for this approximation by treating the spin degrees of freedom using perturbation theory. There were three advantages to doing this: (i) scalar quarks required less computer memory, (ii) simulations using scalar quarks required less computer time, and (iii) it avoided the fermion doubling problem. Their lattice QCD computation[7] of the meson mass spectrum agreed well with the one in nature with the exception of the pion mass, where it is known that treating spin perturbatively is not a good approximation due to approximate spontaneous breaking of chiral symmetry. The lattice computation of the baryon spectrum was equally impressive.[8] Samuel and Moriarty went on to make mass predictions for hadrons involving the bottom quark that had not yet been produced in accelerators.[9] These predictions were later confirmed except for the one for the
Λ
b baryon.[10]

Supersymmetry work edit

Samuel's most important work in supersymmetry arose in a collaboration with the theorist Julius Wess in a publication called "Secret Supersymmetery."[11] In this work, the two physicists constructed an effective low-energy theory of the supersymmetric generalization of the Standard Model of particle physics for the situation in which supersymmetry is spontaneously broken. The main conclusion was: Although there may be few low-energy manifestations of spontaneously broken supersymmetry, there should be at least one charged Higgs field and two neutral Higgs fields beyond the usual neutral one of the Standard Model. All supersymmetric extensions of the Standard Model have these extra spin-0 boson particles. The important conclusion is that if additional Higgs particles are discovered in nature then it is suggestive of an underlying supersymmetric structure even if the supersymmetric partners of the particles in the Standard Model are not observed experimentally.

String theory work edit

Samuel's most important contribution in string theory was the development of off-shell conformal field theory.[12][13] This allowed the computation of the scattering of string states when the on-shell condition E2 = m2c4 + p2c2 is analytically continued so that it no longer holds.[12] The off-shell extension of string scattering amplitudes was thought to be impossible because of a no-go theorem.[14] However, Samuel was able to use Witten's version of string field theory to achieve this result. One of the assumptions of the "no-go" theorem was avoided (the use of an infinite number of ghost states).

Bosonic technicolor edit

Samuel is the creator of bosonic technicolor.[15] Two approaches to solving to the hierarchy problem are technicolor and supersymmetry. The former has difficulties with flavor-changing neutral currents and light pseudo-Goldstone bosons, while the latter predicts superpartner particles that have not been currently observed. Bosonic technicolor is a supersymmetric version of technicolor that eliminates the difficulties that technicolor and supersymmetry have separately. In this model, the masses of superpartners can be about two orders of magnitude higher than in usual supersymmetry extensions of the standard model.

Neutrino oscillations in dense neutrino gases edit

Because neutrinos have masses, the three flavors of neutrinos (electron neutrino
ν
e, muon neutrino
ν
μ and tau neutrino
ν
τ) change into each other and back, a phenomenon called neutrino oscillations. When one has a dense gas of neutrinos, it is not straightforward to determine how neutrino oscillations behave. This is because the oscillation of a single neutrino in the gas depends on the flavors of the neutrinos nearby, and the oscillation of the nearby neutrinos depend on the flavor of that single neutrino (and of other individual nearby neutrinos). Samuel was the first to develop a self-consistent formalism to address this.[16] He observed a number of interesting phenomena that can occur in such systems including a self-induced Mikheyev–Smirnov–Wolfenstein effect and a parametric resonant conversion.

Samuel and colleague Alan Kostelecký have used Samuel's formalism to analyze neutrino oscillations in the early universe.[17]

Awards and prizes edit

Samuel has received a number of awards for his research including a Control Data Corporation PACER Award (with Dr. K. M. Moriarty) for outstanding computer programming, an Alexander von Humboldt Fellowship, and the Chester–Davis Prize (from Indiana University). He was one of 90 scientists in 1984 to be honored as an Alfred P. Sloan Research Recipient.[18]

References edit

  1. ^ Samuel, Stuart (2003). "On the Speed of Gravity and the v/c Corrections to the Shapiro Time Delay". Phys. Rev. Lett. 90 (23): 231101. arXiv:astro-ph/0304006. Bibcode:2003PhRvL..90w1101S. doi:10.1103/PhysRevLett.90.231101. PMID 12857246. S2CID 15905017.
  2. ^ Kostelecký, V. Alan; Samuel, Stuart (1989). "Spontaneous breaking of Lorentz symmetry in string theory". Physical Review D. APS. 39 (2): 683–685. Bibcode:1989PhRvD..39..683K. doi:10.1103/PhysRevD.39.683. hdl:2022/18649. PMID 9959689.
  3. ^ Samuel, Stuart (1978). "The Grand Partition Function in Field Theory with Applications to Sine-Gordon". Phys. Rev. D. 18 (6): 1916. Bibcode:1978PhRvD..18.1916S. doi:10.1103/PhysRevD.18.1916.
  4. ^ a b Samuel, Stuart (1980). "The Use of Anticommuting Integrals in Statistical Mechanics. 1". J. Math. Phys. 21 (12): 2806–2814. Bibcode:1980JMP....21.2806S. doi:10.1063/1.524404.
  5. ^ a b Samuel, Stuart (1980). "The Use of Anticommuting Integrals in Statistical Mechanics. 2". J. Math. Phys. 21 (12): 2815. Bibcode:1980JMP....21.2815S. doi:10.1063/1.524405.
  6. ^ a b Samuel, Stuart (1980). "The Use of Anticommuting Integrals in Statistical Mechanics. 3". J. Math. Phys. 21 (12): 2820. Bibcode:1980JMP....21.2820S. doi:10.1063/1.524406.
  7. ^ Samuel, Stuart; Moriarty, K.J.M. (1985). "Precise hadron mass calculations from lattice QCD". Phys. Lett. B. 158 (5): 437–441. Bibcode:1985PhLB..158..437S. doi:10.1016/0370-2693(85)90449-6.
  8. ^ Samuel, Stuart; Moriarty, K.J.M. (1986). "Precise Baryon Mass Calculations From Scalar Lattice QCD". Phys. Lett. B. 166 (4): 413–418. Bibcode:1986PhLB..166..413S. doi:10.1016/0370-2693(86)91590-X.
  9. ^ Samuel, Stuart; Moriarty, K.J.M. (1986). "Beautiful Mass Predictions From Scalar Lattice QCD" (PDF). Phys. Lett. B. 175 (2): 197–201. Bibcode:1986PhLB..175..197S. doi:10.1016/0370-2693(86)90715-X.
  10. ^ Martin, Andre; Richard, J.M. (1987). "Beautiful and Other Heavy Baryons Revisited". Phys. Lett. B. 185 (3–4): 426–430. Bibcode:1987PhLB..185..426M. doi:10.1016/0370-2693(87)91029-X.
  11. ^ Samuel, Stuart; Wess, Julius (1983). "Secret Supersymmetry". Nucl. Phys. B. 233 (3): 488–510. Bibcode:1984NuPhB.233..488S. doi:10.1016/0550-3213(84)90580-7.
  12. ^ a b Samuel, Stuart (1988). "Covariant Off-shell String Amplitudes". Nucl. Phys. B. 308 (2–3): 285–316. Bibcode:1988NuPhB.308..285S. doi:10.1016/0550-3213(88)90566-4.
  13. ^ Bluhm, Robert; Samuel, Stuart (1988). "Off-shell Conformal Field Theory". Nucl. Phys. B. 308 (2): 317–360. Bibcode:1989NuPhB.325..275B. doi:10.1016/0550-3213(89)90458-6.
  14. ^ Collins, PV; Friedman, KA (1975). "Off-Shell Amplitudes and Currents in the Dual Resonance Model". Nuovo Cimento A. 28 (2): 173–192. Bibcode:1975NCimA..28..173C. doi:10.1007/BF02820878. S2CID 117078172.
  15. ^ Samuel, Stuart (1990). "Bosonic Technicolor". Nucl. Phys. B. 347 (3): 625–650. Bibcode:1990NuPhB.347..625S. doi:10.1016/0550-3213(90)90378-Q.
  16. ^ Samuel, Stuart (1993). "Neutrino oscillations in dense neutrino gases". Phys. Rev. D. 48 (4): 1462–1477. Bibcode:1993PhRvD..48.1462S. doi:10.1103/PhysRevD.48.1462. PMID 10016384.
  17. ^ Kostelecký, Alan; Samuel, Stuart (1994). "Nonlinear neutrino oscillations in the expanding universe" (PDF). Phys. Rev. D. 49 (4): 1740–1757. Bibcode:1994PhRvD..49.1740K. doi:10.1103/PhysRevD.49.1740. hdl:2022/18663. PMID 10017160.
  18. ^ "90 Receive Sloan Foundation Grants". The New York Times. 11 March 1984.

External links edit

  • INSPIRE's list of Samuel's physics papers

December 15, 2023
stuart, samuel, physicist, stuart, samuel, theoretical, physicist, known, work, speed, gravity, work, with, alan, kostelecký, spontaneous, lorentz, violation, string, theory, called, bumblebee, model, also, made, significant, contributions, field, theory, part. Stuart Samuel is a theoretical physicist known for his work 1 on the speed of gravity and for his work 2 with Alan Kostelecky on spontaneous Lorentz violation in string theory now called the Bumblebee model He also made significant contributions in field theory and particle physics Samuel graduated from Princeton University with a Bachelor of Arts in mathematics in 1975 and in 1979 he graduated from the UC Berkeley with a Doctor of Philosophy in physics He was formerly a member of the Institute for Advanced Study at Princeton a professor of physics at Columbia University and a professor of physics at City College of New York Contents 1 Earlier work 2 Scalar lattice QCD 3 Supersymmetry work 4 String theory work 5 Bosonic technicolor 6 Neutrino oscillations in dense neutrino gases 7 Awards and prizes 8 References 9 External linksEarlier work editIn early work Samuel used particle field theory methods to obtain results in statistical mechanics 3 4 5 6 In particular Samuel uncovered a particularly simple way to solve the two dimensional Ising model It was shown to be equivalent to a non interacting field theory of fermionic like particles This allowed a rapid computation of the partition function 4 and correlation functions 5 Samuel went on to treat certain interacting statistical mechanics systems using perturbative field theory 6 Scalar lattice QCD editIn 1985 Samuel and co worker K J M Moriarty were among the first to obtain a reasonably accurate computation of the hadron mass spectrum using computer simulations of lattice quantum chromodynamics QCD They overcame the difficulties that other theorists were encountering at the time by making an approximation They replaced the spin 1 2 fermionic quarks with spin zero scalar particles and corrected for this approximation by treating the spin degrees of freedom using perturbation theory There were three advantages to doing this i scalar quarks required less computer memory ii simulations using scalar quarks required less computer time and iii it avoided the fermion doubling problem Their lattice QCD computation 7 of the meson mass spectrum agreed well with the one in nature with the exception of the pion mass where it is known that treating spin perturbatively is not a good approximation due to approximate spontaneous breaking of chiral symmetry The lattice computation of the baryon spectrum was equally impressive 8 Samuel and Moriarty went on to make mass predictions for hadrons involving the bottom quark that had not yet been produced in accelerators 9 These predictions were later confirmed except for the one for the Lb baryon 10 Supersymmetry work editSamuel s most important work in supersymmetry arose in a collaboration with the theorist Julius Wess in a publication called Secret Supersymmetery 11 In this work the two physicists constructed an effective low energy theory of the supersymmetric generalization of the Standard Model of particle physics for the situation in which supersymmetry is spontaneously broken The main conclusion was Although there may be few low energy manifestations of spontaneously broken supersymmetry there should be at least one charged Higgs field and two neutral Higgs fields beyond the usual neutral one of the Standard Model All supersymmetric extensions of the Standard Model have these extra spin 0 boson particles The important conclusion is that if additional Higgs particles are discovered in nature then it is suggestive of an underlying supersymmetric structure even if the supersymmetric partners of the particles in the Standard Model are not observed experimentally String theory work editSamuel s most important contribution in string theory was the development of off shell conformal field theory 12 13 This allowed the computation of the scattering of string states when the on shell condition E2 m2c4 p2c2 is analytically continued so that it no longer holds 12 The off shell extension of string scattering amplitudes was thought to be impossible because of a no go theorem 14 However Samuel was able to use Witten s version of string field theory to achieve this result One of the assumptions of the no go theorem was avoided the use of an infinite number of ghost states Bosonic technicolor editSamuel is the creator of bosonic technicolor 15 Two approaches to solving to the hierarchy problem are technicolor and supersymmetry The former has difficulties with flavor changing neutral currents and light pseudo Goldstone bosons while the latter predicts superpartner particles that have not been currently observed Bosonic technicolor is a supersymmetric version of technicolor that eliminates the difficulties that technicolor and supersymmetry have separately In this model the masses of superpartners can be about two orders of magnitude higher than in usual supersymmetry extensions of the standard model Neutrino oscillations in dense neutrino gases editBecause neutrinos have masses the three flavors of neutrinos electron neutrino ne muon neutrino nm and tau neutrino nt change into each other and back a phenomenon called neutrino oscillations When one has a dense gas of neutrinos it is not straightforward to determine how neutrino oscillations behave This is because the oscillation of a single neutrino in the gas depends on the flavors of the neutrinos nearby and the oscillation of the nearby neutrinos depend on the flavor of that single neutrino and of other individual nearby neutrinos Samuel was the first to develop a self consistent formalism to address this 16 He observed a number of interesting phenomena that can occur in such systems including a self induced Mikheyev Smirnov Wolfenstein effect and a parametric resonant conversion Samuel and colleague Alan Kostelecky have used Samuel s formalism to analyze neutrino oscillations in the early universe 17 Awards and prizes editSamuel has received a number of awards for his research including a Control Data Corporation PACER Award with Dr K M Moriarty for outstanding computer programming an Alexander von Humboldt Fellowship and the Chester Davis Prize from Indiana University He was one of 90 scientists in 1984 to be honored as an Alfred P Sloan Research Recipient 18 References edit Samuel Stuart 2003 On the Speed of Gravity and the v c Corrections to the Shapiro Time Delay Phys Rev Lett 90 23 231101 arXiv astro ph 0304006 Bibcode 2003PhRvL 90w1101S doi 10 1103 PhysRevLett 90 231101 PMID 12857246 S2CID 15905017 Kostelecky V Alan Samuel Stuart 1989 Spontaneous breaking of Lorentz symmetry in string theory Physical Review D APS 39 2 683 685 Bibcode 1989PhRvD 39 683K doi 10 1103 PhysRevD 39 683 hdl 2022 18649 PMID 9959689 Samuel Stuart 1978 The Grand Partition Function in Field Theory with Applications to Sine Gordon Phys Rev D 18 6 1916 Bibcode 1978PhRvD 18 1916S doi 10 1103 PhysRevD 18 1916 a b Samuel Stuart 1980 The Use of Anticommuting Integrals in Statistical Mechanics 1 J Math Phys 21 12 2806 2814 Bibcode 1980JMP 21 2806S doi 10 1063 1 524404 a b Samuel Stuart 1980 The Use of Anticommuting Integrals in Statistical Mechanics 2 J Math Phys 21 12 2815 Bibcode 1980JMP 21 2815S doi 10 1063 1 524405 a b Samuel Stuart 1980 The Use of Anticommuting Integrals in Statistical Mechanics 3 J Math Phys 21 12 2820 Bibcode 1980JMP 21 2820S doi 10 1063 1 524406 Samuel Stuart Moriarty K J M 1985 Precise hadron mass calculations from lattice QCD Phys Lett B 158 5 437 441 Bibcode 1985PhLB 158 437S doi 10 1016 0370 2693 85 90449 6 Samuel Stuart Moriarty K J M 1986 Precise Baryon Mass Calculations From Scalar Lattice QCD Phys Lett B 166 4 413 418 Bibcode 1986PhLB 166 413S doi 10 1016 0370 2693 86 91590 X Samuel Stuart Moriarty K J M 1986 Beautiful Mass Predictions From Scalar Lattice QCD PDF Phys Lett B 175 2 197 201 Bibcode 1986PhLB 175 197S doi 10 1016 0370 2693 86 90715 X Martin Andre Richard J M 1987 Beautiful and Other Heavy Baryons Revisited Phys Lett B 185 3 4 426 430 Bibcode 1987PhLB 185 426M doi 10 1016 0370 2693 87 91029 X Samuel Stuart Wess Julius 1983 Secret Supersymmetry Nucl Phys B 233 3 488 510 Bibcode 1984NuPhB 233 488S doi 10 1016 0550 3213 84 90580 7 a b Samuel Stuart 1988 Covariant Off shell String Amplitudes Nucl Phys B 308 2 3 285 316 Bibcode 1988NuPhB 308 285S doi 10 1016 0550 3213 88 90566 4 Bluhm Robert Samuel Stuart 1988 Off shell Conformal Field Theory Nucl Phys B 308 2 317 360 Bibcode 1989NuPhB 325 275B doi 10 1016 0550 3213 89 90458 6 Collins PV Friedman KA 1975 Off Shell Amplitudes and Currents in the Dual Resonance Model Nuovo Cimento A 28 2 173 192 Bibcode 1975NCimA 28 173C doi 10 1007 BF02820878 S2CID 117078172 Samuel Stuart 1990 Bosonic Technicolor Nucl Phys B 347 3 625 650 Bibcode 1990NuPhB 347 625S doi 10 1016 0550 3213 90 90378 Q Samuel Stuart 1993 Neutrino oscillations in dense neutrino gases Phys Rev D 48 4 1462 1477 Bibcode 1993PhRvD 48 1462S doi 10 1103 PhysRevD 48 1462 PMID 10016384 Kostelecky Alan Samuel Stuart 1994 Nonlinear neutrino oscillations in the expanding universe PDF Phys Rev D 49 4 1740 1757 Bibcode 1994PhRvD 49 1740K doi 10 1103 PhysRevD 49 1740 hdl 2022 18663 PMID 10017160 90 Receive Sloan Foundation Grants The New York Times 11 March 1984 External links editINSPIRE s list of Samuel s physics papers Retrieved from https en wikipedia org w index php title Stuart Samuel physicist amp oldid 1161304967, wikipedia, wiki, book, books, library,

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