Border of spacetime

Harada, Tomohiro; Nakao, Ken–ichi

doi:10.1103/physrevd.70.041501

Cited by 39 publications

(54 citation statements)

References 12 publications

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“…The QSR investigations of these particular mesons exhibit a congruent pattern: Pseudo-scalar D mesons attracted much attention, where recent studies focus either on precise predictions of spectral or QCD parameters in vacuum [41] or on medium modifications [33,46]; whereas scalar D meson QSRs have been rarely analyzed so far, primarily in vacuum [42,[47][48][49] or cold nuclear matter [50]. As the idea of heavy-light mesons as probes of DχSB gains acceptance also further investigations of chiral partners based on different approaches are performed [26,[51][52][53][54] emphasizing the role of the scalar D meson. Accordingly, we set up the in-medium QSR for the scalar D meson in order to seek for signals of chiral restoration at finite temperatures in a particle-anti-particle symmetric medium.…”

Section: Introductionmentioning

confidence: 99%

Chiral-partner D mesons in a heat bath within QCD sum rules

Buchheim

Hilger

Kämpfer

et al. 2018

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

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Utilizing QCD sum rules, we extract the temperature dependences of the spectral properties of the pseudo-scalar and scalar D mesons regarded as chiral partners. Besides the masses also decay constants are analyzed as the D meson yields in heavy-ion collisions may be sensitive to their altered decay properties in an ambient strongly interacting medium. Our findings are (i) a decreasing scalar D meson mass for growing temperatures while its pseudo-scalar partner meson seems hardly affected, which is in qualitative agreement with hadronic model calculations; (ii) inferring an equally weak temperature dependence of the pseudo-scalar D meson decay properties the decreasing residua and decay constants of the scalar particle point towards partial chiral restoration. As a bonus of our analysis in the pseudo-scalar sector we determine the pseudo-scalar decay constant at vanishing temperature. Due to the connection to particular leptonic branching fractions this decay constant is of great interest allowing for the determination of the off-diagonal CKM matrix element |V cd | at zero temperature. arXiv:1801.01472v1 [nucl-th] 4 Jan 2018 etc. Further interesting aspects of open flavor mesons are rare CP-violating decays [10] and their role w. r. t. exotic quantum numbers [11]. In this paper, we utilize the QCD sum rule (QSR) tool [12] and compare chiral-partner open-charm mesons, that is the pseudo-scalar (P) D meson and the scalar (S) D meson. Mass modificationsChiral partners in the light-quark sector, e. g. the spectra of ρ and a 1 mesons, should become mass degenerate under chiral restoration [13,14], but also the individual fate of a member in the chiral multiplet under chiral restoration is of interest [15][16][17]. As mentioned above, also the open-charm mesons are subject to chiral restoration, albeit in a different manner.Studying patterns of dynamical chiral symmetry breaking (DχSB) with mesons containing a heavy and a light quark seems to be superimposed by the explicit symmetry breaking due to the non-negligible heavy-quark mass. However, the original light-quark problem can be translated into the heavy-light sector, if the chiral symmetry transformations are restricted to the light-quark content. As exemplified in Appendix A for the D 0 meson, the respective pseudo-scalar current can be transformed into the scalar current by a finite chiral transformation with a specific set of rotation parameters. Thus, the pseudo-scalar and scalar D 0 mesons are qualified as chiral partners, which would have degenerate spectral properties in a chirally symmetric world. In contrast, the experimentally verified masses [3], m P = 1.865 GeV and m S = 2.318 GeV, deviate by about 450 MeV (similar to the a 1 -ρ mass splitting) signaling the dynamical breakdown of chiral symmetry which is driven by order parameters [18-21], e. g. most prominently by the chiral condensate 〈qq〉 as well as by chirally odd four-quark condensates which vanish in a chiral restoration scenario. The DχSB phenomenology, e. g. the splitting of chiral partner mass...

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Section: Introductionmentioning

confidence: 99%

Chiral-partner D mesons in a heat bath within QCD sum rules

Buchheim

Hilger

Kämpfer

et al. 2018

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

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“…The cosmic censorship conjecture and naked singularity formation is of interest not only in a mathematical aspect of general relativity, but also in finding the cut-off energy scale of general relativity. In other words, a spacetime domain near a naked singularity with infinite curvature, which we call a border of spacetime [6], may be a window into new physics beyond general relativity. Even if the curvature scale does not exceed the cut-off scale, it would provide the locally high energy region in which unknown high energy particle physics phenomena may take place.…”

Section: Introductionmentioning

confidence: 99%

3D simulation of spindle gravitational collapse of a collisionless particle system

Yoo¹,

Harada²,

Okawa³

2017

Class. Quantum Grav.

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We simulate the spindle gravitational collapse of a collisionless particle system in a 3D numerical relativity code and compare the qualitative results with the old work done by Shapiro and Teukolsky [1]. The simulation starts from the prolate-shaped distribution of particles and a spindle collapse is observed. The peak value and its spatial position of curvature invariants are monitored during the time evolution.We find that the peak value of the Kretschmann invariant takes a maximum at some moment, when there is no apparent horizon, and its value is greater for a finer resolution, which is consistent with what is reported in Ref. [1]. We also find a similar tendency for the Weyl curvature invariant. Therefore, our results lend support to the formation of a naked singularity as a result of the axially symmetric spindle collapse of a collisionless particle system in the limit of infinite resolution. However, unlike in Ref.[1], our code does not break down then but go well beyond. We find that the peak values of the curvature invariants start to gradually decrease with time for a certain period of time. Another notable difference from Ref.[1] is that, in our case, the peak position of the Kretschmann curvature invariant is always inside the matter distribution.

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“…[9] for a review). The medium modified heavy-light meson spectrum has been studied by several groups in the literature [10][11][12][13][14][15][16]. In Ref.…”

Section: Introductionmentioning

confidence: 99%

“…In Refs. [10,15,16], by regarding the D * 0 (J P = 0 + ) and D 1 (J P = 1 + ) mesons as the chiral partners to D and D * mesons, it was shown that the mass splitting of the chiral partner is reduced at high density and temperature. In particular in Ref.…”

Section: Introductionmentioning

confidence: 99%

Relation between the mass modification of heavy–light mesons and the chiral symmetry structure in dense matter

Harada

Suenaga

et al. 2017

Progress of Theoretical and Experimental Physics

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We point out that the study of the density dependences of the masses of heavy-light mesons give some clues to the chiral symmetry structure in nuclear matter. We include the omega meson effect as well as the sigma meson effect at mean field level on the density dependence of the masses of heavylight mesons with chiral partner structure. It is found that the omega meson affects the masses of the heavy-light mesons and their antiparticles in the opposite way, while it affects the masses of chiral partners in the same way. This is because the ω meson is sensitive to the baryon number of the light degrees included in the heavy-light mesons. We also show that the mass difference between chiral partners is proportional to the mean field of sigma, reflecting the partial restoration of chiral symmetry in the nuclear matter. In addition to the general illustration of the density dependence of the heavy-light meson masses, we consider two concrete models for nuclear matter, the parity doublet model and skyrmion crystal model in the sense of mean field approximation.

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Border of spacetime

Cited by 39 publications

References 12 publications

Chiral-partner D mesons in a heat bath within QCD sum rules

Chiral-partner D mesons in a heat bath within QCD sum rules

3D simulation of spindle gravitational collapse of a collisionless particle system

Relation between the mass modification of heavy–light mesons and the chiral symmetry structure in dense matter

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