We analyze color superconductivity of one massive flavor quark matter at
moderate baryon density with a spin-zero color-sextet condensate. The most
general Higgs-type ground-state expectation value of the order parameter
implies complete breakdown of the SU(3)xU(1) symmetry. However, both the
conventional fourth-order polynomial effective bosonic description, and the
NJL-type fermionic description in the mean-field approximation favor an
enhanced SO(3) symmetry of the ground state. We ascribe this finding to the
failure of the mean-field approximation and propose that a more sophisticated
technique is needed.Comment: 8 pages, REVTeX4; v2:references added; v3: corrected, new four-quark
interaction proposed, extensive discussion of the assumptions added; version
to appear in Phys. Rev.
The workshop “Shedding light on X17” brings together scientists looking for the existence of a possible new light particle, often referred to as X17. This hypothetical particle can explain the resonant structure observed at $$\sim $$
∼
17 MeV in the invariant mass of electron-positron pairs, produced after excitation of nuclei such as $$^8\hbox {Be}$$
8
Be
and $$^4\hbox {He}$$
4
He
by means of proton beams at the Atomki Laboratory in Debrecen. The purpose of the workshop is to discuss implications of this anomaly, in particular theoretical interpretations as well as present and future experiments aiming at confirming the result and/or at providing experimental evidence for its interpretation.
A theoretical ab-initio investigation of exchange interaction between Cu atoms in an insulating antiferromagnet Cu(H2O)2(en)SO4, en = C2H8N2, is reported. While the previous experimental studies described the system's magnetism to be quasi-two-dimensional, our results, based on a mapping of the system onto an effective Heisenberg model, rather support a quasi-one-dimensional character with the exchange coupling between the Cu atoms being propagated mainly along a zigzag line lying in the crystal's bc plane and connecting the Cu atoms through the N atoms. Further, the direction of magnetic moments on the Cu atoms is suggested to be nearly along the crystal's a axis. A check of the change in the exchange constants induced either by external pressure or by various values of U in the GGA + U approximation is made. Finally, based on experimental values of positions of broad maxima in magnetic-susceptibility and specific-heat curves and using theoretical expressions available in the literature a relevant value of the U parameter and related expected value of the electronic gap are estimated to be about 5 eV and 2 eV, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.