Publisher’s Note:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>ρ</mml:mi><mml:mtext>‐</mml:mtext><mml:mi>ω</mml:mi></mml:mrow></mml:math>splitting and mixing in nuclear matter [Phys. Rev. C<b>70</b>, 035207 (2004)]

Zschocke, Sven; Kämpfer, B.

doi:10.1103/physrevc.70.049901

Cited by 9 publications

(26 citation statements)

References 15 publications

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“…The estimate in [11] points to small values of κ (1) 1,2 thus having essentially the density dependence of the combined pure flavor scalar dimension-6 condensates…”

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confidence: 91%

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Evidence for In-Medium Changes of Four-Quark Condensates

Thomas

Zschocke²,

Kämpfer³

2005

Phys. Rev. Lett.

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Utilizing the QCD sum rule approach to the behavior of the ω meson in nuclear matter we derive evidence for in-medium changes of particular four-quark condensates from the recent CB-TAPS experiment for the reaction γ + A → A ′ + ω(→ π 0 γ) with A = Nb and LH2. The chiral condensate qq is an order parameter for the spontaneous breaking of chiral symmetry in the theory of strong interaction (cf. e.g. [1] for introducing this topic). The role of qq is highlighted, e.g., by the GellMann-Oakes-Renner relation m 2 π f 2 π ∝ − qq (cf. [2]; the explicit chiral symmetry breaking is essential for a finite pion mass m π , while the relation of the pion decay constant f π to qq qualifies the latter as an order parameter) or by Ioffe's formula M N ∝ − qq for the nucleon mass (cf. [3] and in particular the discussion in [4]). There is growing evidence that the quark-gluon condensate is another order parameter [5]. The QCD trace anomaly related to scale invariance breaking gives rise to the gluon condensate. There are many other condensates characterizing the complicated structure of the QCD vacuum. In a medium, described by temperature and baryon density n, these condensates change, i.e., the ground state is rearranged. Since hadrons are considered as excitations above the vacuum, a vacuum change should manifest itself as a change of the hadronic excitation spectrum. This idea triggered widespread activities to search for in-medium modifications of hadrons. Such in-medium modifications of hadronic observables are found (cf. the lists in [6,7]), and it is timely to relate them to corresponding order parameters.We deduce here evidence for a noticeable drop of inmedium four-quark condensates in cold nuclear matter from results of the recent CB-TAPS experiment [6] for the reaction γ + A → A ′ + ω(→ π 0 γ). The CB-TAPS collaboration observed the occurrence of additional lowenergy ω decay strength for a Nb (A = 93) target compared to a LH 2 (A = 1) target. The link of observables to quark and gluon condensates is established by QCD sum rules [8], which are expected to be sensitive to four-quark condensates in the vector channels [9]. Four-quark condensate combinations which contain only left-right helicity flipping terms (as the chiral condensate does) represent other order parameters of chiral symmetry.Concentrating on the iso-scalar part of the causal current-current correlator [3]here for the ω meson with the current j ω µ = ūγ µ u +dγ µ d /2 and nuclear matter states |Ω (the symbol T means time ordering, and u, d denote quark field operators), an operator product expansion and a Borel transformation (cf. [3,10] for arguments in favor of Borel sum rules) of the twice-subtracted dispersion relation result inwhere Π ω (0, n) = 9n/(4M N ) with the nucleon mass M N is a subtraction constant having the meaning of Landau damping or ω N forward scattering amplitude, and the coefficients c j contain condensates and Wilson coefficients; M is the Borel mass. The first coefficients c j have been spelled out in many papers (cf.[11] for our ...

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“…The estimate in [11] points to small values of κ (1) 1,2 thus having essentially the density dependence of the combined pure flavor scalar dimension-6 condensates…”

mentioning

confidence: 91%

“…The first coefficients c j have been spelled out in many papers (cf. [11] for our notation, and [12] for an anomalous contribution) and are not reproduced here in full length.…”

mentioning

confidence: 99%

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Evidence for In-Medium Changes of Four-Quark Condensates

Thomas

Zschocke²,

Kämpfer³

2005

Phys. Rev. Lett.

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“…All existing matter-induced mixing calculations, however, suggest that, at least in the ρ-ω sector, the inclusion of such a matter-induced mixing amplitude into the two-body NN interaction potential can significantly change the results both qualitatively and quantitatively. It is also to be noted that such mixing amplitudes, in asymmetric nuclear matter (ANM), have a nonzero contribution even if the quark or nucleon masses are taken to be equal [26][27][28][29][30]. We consider both of these mechanisms to construct the CSV potential.…”

Section: Introductionmentioning

confidence: 97%

“…[26] and was subsequently studied in Refs. [27][28][29][30]. For the case of the π -η meson also such asymmetry-driven mixing is studied in Ref.…”

Section: Introductionmentioning

confidence: 98%

Matter-induced charge-symmetry-violatingNNpotential

2010

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Matter-induced charge symmetry breaking and the pion form factor in nuclear medium

Roy¹,

Dutt-Mazumder²,

Sarkar³

et al. 2008

J. Phys. G: Nucl. Part. Phys.

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Medium modification of pion form factor has been evaluated in asymmetric nuclear matter (ANM). It is shown that both the shape and the pole position of the pion form factor in dense asymmetric nuclear matter is different from its vacuum counterpart with ρ-ω mixing. This is due to the density and asymmetry dependent ρ-ω mixing which could even dominate over its vacuum counterpart in matter. Results are presented for arbitrarily mixing angle. Effect of the inmedium pion factor on experimental observables e.g., invariant mass distribution of lepton pairs has been demonstrated.

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Publisher’s Note:ρ‐ωsplitting and mixing in nuclear matter [Phys. Rev. C70, 035207 (2004)]

Cited by 9 publications

References 15 publications

Evidence for In-Medium Changes of Four-Quark Condensates

Evidence for In-Medium Changes of Four-Quark Condensates

Matter-induced charge-symmetry-violatingNNpotential

Matter-induced charge symmetry breaking and the pion form factor in nuclear medium

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