Abstract:The critical behavior of a complex N -component order parameter Ginzburg-Landau model with isotropic and cubic interactions describing antiferromagnetic and structural phase transitions in certain crystals with complicated ordering is studied in the framework of the four-loop renormalization group (RG) approach in (4 − ε) dimensions. By using dimensional regularization and the minimal subtraction scheme, the perturbative expansions for RG functions are deduced and resummed by the Borel-Leroy transformation com… Show more
“…First, we focus on the first kink, which approaches the value (∆ φ , ∆ X ) = (0.5, 2) as m → ∞. In [15], it was observed that this limit is compatible with the results in the expansion [3,21,24,25] expanded at large m, where indeed ∆ φ → d−2 2 and ∆ X → 2 up to m −1 corrections. We show here that the m −1 corrections can be computed in a perturbative expansion similar to the usual large N expansion of the O(N ) model (see e.g.…”
Section: Introductionsupporting
confidence: 56%
“…While the critical exponents corresponding to the second kink show reasonable agreement, within uncertainties, with the results of [8,19], neither set of values is compatible with the predictions from the expansion, which gives β = 0.370 (5) and ν = 0.715(10) [20,21]. 3 Although it was speculated in [15] that the first kink may be related to the expansion through the large m limit, the results of that study were not sufficient to make any conclusive statements.…”
Section: Introductionsupporting
confidence: 49%
“…Conformal field theories with MN symmetry have been studied in the d = 4 − expansion over a long time, [20,21,24,25,39,40], most recently in section 5.2.2. of [3]. From the beta functions of the couplings λ and g in the Lagrangian (1), four fixed points are found in the expansion: mn free fields, n decoupled critical O(m) models, the critical O(mn) model, and the perturbative MN CFT.…”
Section: Results From Previous Studies In the Expansionmentioning
Fixed points in three dimensions described by conformal field
theories with \ensuremath{M N}_{m,n} = O(m)^n\rtimes S_nMNm,n=O(m)n⋊Sn
global symmetry have extensive applications in critical phenomena.
Associated experimental data for m=n=2m=n=2
suggest the existence of two non-trivial fixed points, while the
\varepsilonε
expansion predicts only one, resulting in a puzzling state of affairs. A
recent numerical conformal bootstrap study has found two kinks for small
values of the parameters mm
and nn,
with critical exponents in good agreement with experimental
determinations in the m=n=2m=n=2
case. In this paper we investigate the fate of the corresponding fixed
points as we vary the parameters mm
and nn.
We find that one family of kinks approaches a perturbative limit as
mm
increases, and using large spin perturbation theory we construct a large
mm
expansion that fits well with the numerical data. This new expansion,
akin to the large NN
expansion of critical O(N)O(N)
models, is compatible with the fixed point found in the
\varepsilonε
expansion. For the other family of kinks, we find that it persists only
for n=2n=2,
where for large mm
it approaches a non-perturbative limit with
\Delta_\phi\approx 0.75Δϕ≈0.75.
We investigate the spectrum in the case \ensuremath{M N}_{100,2}MN100,2
and find consistency with expectations from the lightcone bootstrap.
“…First, we focus on the first kink, which approaches the value (∆ φ , ∆ X ) = (0.5, 2) as m → ∞. In [15], it was observed that this limit is compatible with the results in the expansion [3,21,24,25] expanded at large m, where indeed ∆ φ → d−2 2 and ∆ X → 2 up to m −1 corrections. We show here that the m −1 corrections can be computed in a perturbative expansion similar to the usual large N expansion of the O(N ) model (see e.g.…”
Section: Introductionsupporting
confidence: 56%
“…While the critical exponents corresponding to the second kink show reasonable agreement, within uncertainties, with the results of [8,19], neither set of values is compatible with the predictions from the expansion, which gives β = 0.370 (5) and ν = 0.715(10) [20,21]. 3 Although it was speculated in [15] that the first kink may be related to the expansion through the large m limit, the results of that study were not sufficient to make any conclusive statements.…”
Section: Introductionsupporting
confidence: 49%
“…Conformal field theories with MN symmetry have been studied in the d = 4 − expansion over a long time, [20,21,24,25,39,40], most recently in section 5.2.2. of [3]. From the beta functions of the couplings λ and g in the Lagrangian (1), four fixed points are found in the expansion: mn free fields, n decoupled critical O(m) models, the critical O(mn) model, and the perturbative MN CFT.…”
Section: Results From Previous Studies In the Expansionmentioning
Fixed points in three dimensions described by conformal field
theories with \ensuremath{M N}_{m,n} = O(m)^n\rtimes S_nMNm,n=O(m)n⋊Sn
global symmetry have extensive applications in critical phenomena.
Associated experimental data for m=n=2m=n=2
suggest the existence of two non-trivial fixed points, while the
\varepsilonε
expansion predicts only one, resulting in a puzzling state of affairs. A
recent numerical conformal bootstrap study has found two kinks for small
values of the parameters mm
and nn,
with critical exponents in good agreement with experimental
determinations in the m=n=2m=n=2
case. In this paper we investigate the fate of the corresponding fixed
points as we vary the parameters mm
and nn.
We find that one family of kinks approaches a perturbative limit as
mm
increases, and using large spin perturbation theory we construct a large
mm
expansion that fits well with the numerical data. This new expansion,
akin to the large NN
expansion of critical O(N)O(N)
models, is compatible with the fixed point found in the
\varepsilonε
expansion. For the other family of kinks, we find that it persists only
for n=2n=2,
where for large mm
it approaches a non-perturbative limit with
\Delta_\phi\approx 0.75Δϕ≈0.75.
We investigate the spectrum in the case \ensuremath{M N}_{100,2}MN100,2
and find consistency with expectations from the lightcone bootstrap.
“…14 does not correspond to the O 2,2 chiral fixed point. In [39] it was suggested that this kink may correspond to the fully-interacting theory of the expansion analyzed in [71][72][73][74]. To continue our search for the O 2,2 chiral fixed point, we obtain a bound on the dimension of the first scalar operator in the WX representation.…”
Section: Single Correlator In the O(2) × O(2) Casementioning
Motivated by applications to critical phenomena and open theoretical
questions, we study conformal field theories with
O(m)\times
O(n)O(m)×O(n)
global symmetry in d=3d=3
spacetime dimensions. We use both analytic and numerical bootstrap
techniques. Using the analytic bootstrap, we calculate anomalous
dimensions and OPE coefficients as power series in
\varepsilon=4-dε=4−d
and in 1/n1/n,
with a method that generalizes to arbitrary global symmetry. Whenever
comparison is possible, our results agree with earlier results obtained
with diagrammatic methods in the literature. Using the numerical
bootstrap, we obtain a wide variety of operator dimension bounds, and we
find several islands (isolated allowed regions) in parameter space for
O(2)\times O(n)O(2)×O(n)
theories for various values of nn.
Some of these islands can be attributed to fixed points predicted by
perturbative methods like the \varepsilonε
and large-nn
expansions, while others appear to arise due to fixed points that have
been claimed to exist in resummations of perturbative beta
functions.
“…[16], with the four-loop ǫ expansion of the so called tetragonal model Ref. [39]. The value of n H (m, 4 − ǫ) coincides with N c /m, where N c is the marginal spin dimensionality of the cubic model obtained in [40], according to the symmetry argument of Refs.…”
We compute the Renormalization Group functions of a Landau-GinzburgWilson Hamiltonian with O(n)×O(m) symmetry up to five-loop in Minimal Subtraction scheme. The line n + (m, d), which limits the region of secondorder phase transition, is reconstructed in the framework of the ǫ = 4 − d expansion for generic values of m up to O(ǫ 5 ). For the physically interesting case of noncollinear but planar orderings (m = 2) we obtain n + (2, 3) = 6.1(6) by exploiting different resummation procedures. We substantiate this results re-analyzing six-loop fixed dimension series with pseudo-ǫ expansion, obtaining n + (2, 3) = 6.22(12). We also provide predictions for the critical exponents characterizing the second-order phase transition occurring for n > n + .
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