The quark and gluon condensates and low-energy QCD theorems in a magnetic field

Agasian, N. O.; Shushpanov, I.A.

doi:10.1016/s0370-2693(99)01414-8

Cited by 96 publications

(88 citation statements)

References 14 publications

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“…It refers to an effect that the chiral condensate increases with the increasing B and thus the transition temperature T c grows with B as well. This has been verified by Almost all earlier low-energy effective models and approximations to QCD [5][6][7][9][10][11][12][13][14][15][16][17][18][19][20] as well as lattice simulations [21][22][23][24][25] in the past twenty years, although several model calculations, such as the two-flavor chiral perturbation theory [26], the linear sigma model without vacuum corrections [27] and the bag model [28], exceptionally obtained a decreasing T c (B) function. However, a recent lattice result [29] surprisingly shows that the transition temperature T c significantly decreases with the increasing magnetic field.…”

Section: Introductionmentioning

confidence: 58%

Spontaneous generation of localCPviolation and inverse magnetic catalysis

Liu

Huang

2014

Phys. Rev. D

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In the chiral symmetric phase, the polarized instanton-anti-instanton molecule pairing induces a nontrivial repulsive interaction in the iso-scalar axial-vector channel. As a consequence, one unusual property is observed that in the chiral restoration phase, there is a first order phase transition for the spontaneous generation of local CP violation and chirality imbalance. Furthermore, it is found that external magnetic fields will lower the critical temperature for the local CP-odd phase transition and catalyze the chirality imbalance, which destroys the chiral condensate with pairing quarks between different chiralities. A reasonable strength of the repulsive interaction in the iso-scalar axial-vector channel can naturally explain the inverse magnetic catalysis around the critical temperature under external magnetic fields.

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Section: Introductionmentioning

confidence: 58%

Spontaneous generation of localCPviolation and inverse magnetic catalysis

Liu

Huang

2014

Phys. Rev. D

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“…The effect of the magnetic field on the dimension-4 gluon condensate has been analyzed in Ref. [15] so that, in principle, one could include it in the same way done here in the case of the chiral condensate. However, the breaking of rotational symmetry will introduce new dimension-4 condensates, 2 previously forbidden by Lorentz invariance in the vacuum (eB ¼ 0), and there is no information on the behavior of these condensates under strong magnetic fields.…”

Section: Qcd Sum Rules In the Vacuummentioning

confidence: 99%

“…The nonperturbative contribution to the correlator that comes from using the propagator in Eq. (15) in the OPE two-point function, after the Borel transform, iŝ…”

Section: B Nonperturbative Qcd Contributionsmentioning

confidence: 99%

Modification of theBmeson mass in a magnetic field from QCD sum rules

et al. 2014

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In this paper, we extend the well-known QCD sum rules used in the calculation of the mass of heavy mesons to estimate the modification of the charged B-meson mass, m B , in the presence of an external Abelian magnetic field, eB. Two simplifying limits were considered: the weak field limit, in which the external field satisfies eB ≪ m 2 (with m being any of the masses involved); and the strong field limit, in which the field strength is small in comparison to the bottom quark mass (or the B-meson mass) squared, but it is large compared to the mass of the light quarks, i.e., m 2 u;d ≪ eB ≪ m 2 b;B . We found that m B decreases with the magnetic field in both of these limits.

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“…In chiral perturbation theory, the power-series expansion of the quark condensate in the magnetic field [7] is performed in the parameter ξ = eB/(4πF π ) 2 . Then, within chiral perturbation theory, the field at ξ < 1 can be treated as weak.…”

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confidence: 99%

Low-energy relation for the trace of the energy–momentum tensor in QCD and the gluon condensate in a magnetic field

Agasian

2016

Jetp Lett.

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A treatment is given of the nonperturbative QCD vacuum in a magnetic field. The low-energy equation for the trace of the energy-momentum tensor in a magnetic field is derived. It is shown that the derivatives with respect to a magnetic field of the quark and gluon contributions to the trace of the energy-momentum tensor are equal.The dependence of the gluon condensate on the magnetic field strength is derived both for strong and weak fields. Quantum-field theories involve important relations following from the symmetry properties of a theory. Search for symmetries and constraints imposed by them on the physical characteristics of the system are of particular importance in QCD, which is a theory with confinement, where "observables" are composite states-hadrons. Low-energy theorems or Ward identities (scale and chiral) are of fundamental importance for a deeper insight into the nonperturbative properties of the QCD vacuum. Low-energy theorems of QCD were obtained in the early 1980s [32]. Low-energy theorems of QCD, which follow from the general symmetry properties and are independent of the details of the confinement mechanism, make it possible to obtain information sometimes otherwise inaccessible. In addition, they can be

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The quark and gluon condensates and low-energy QCD theorems in a magnetic field

Abstract: The low-energy QCD theorems are generalized in the presence of a constant magnetic field H. Two-loop approximation for the vacuum energy density in the framework of the chiral perturbation theory was obtained and the quark and gluon condensates were found as the functions of H.

Cited by 96 publications

References 14 publications

Spontaneous generation of localCPviolation and inverse magnetic catalysis

Spontaneous generation of localCPviolation and inverse magnetic catalysis

Modification of theBmeson mass in a magnetic field from QCD sum rules

Low-energy relation for the trace of the energy–momentum tensor in QCD and the gluon condensate in a magnetic field

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