810 research outputs found
Quark and pion condensation in a chromomagnetic background field
The general features of quark and pion condensation in dense quark matter
with flavor asymmetry have been considered at finite temperature in the
presence of a chromomagnetic background field modelling the gluon condensate.
In particular, pion condensation in the case of a constant abelian
chromomagnetic field and zero temperature has been studied both analytically
and numerically. Under the influence of the chromomagnetic background field the
effective potential of the system is found to have a global minimum for a
finite pion condensate even for small values of the effective quark coupling
constant. In the strong field limit, an effective dimensional reduction has
been found to take place.Comment: 17 pages, 6 figure
Magnetic Oscillations in Dense Cold Quark Matter with Four-Fermion Interactions
The phase structures of Nambu-Jona-Lasinio models with one or two flavours
have been investigated at non-zero values of and , where is an
external magnetic field and is the chemical potential. In the phase
portraits of both models there arise infinitely many massless chirally
symmetric phases, as well as massive ones with spontaneously broken chiral
invariance, reflecting the existence of infinitely many Landau levels. Phase
transitions of first and second orders and a lot of tricritical points have
been shown to exist in phase diagrams. In the massless case, such a phase
structure leads unavoidably to the standard van Alphen-de Haas magnetic
oscillations of some thermodynamical quantities, including magnetization,
pressure and particle density. In the massive case we have found an oscillating
behaviour not only for thermodynamical quantities, but also for a dynamical
quantity as the quark mass. Besides, in this case we have non-standard, i.e.
non-periodic, magnetic oscillations, since the frequency of oscillations is an
-dependent quantity.Comment: latex, 29 pages, 8 figure
A matrix model for the topological string II: The spectral curve and mirror geometry
In a previous paper, we presented a matrix model reproducing the topological
string partition function on an arbitrary given toric Calabi-Yau manifold.
Here, we study the spectral curve of our matrix model and thus derive, upon
imposing certain minimality assumptions on the spectral curve, the large volume
limit of the BKMP "remodeling the B-model" conjecture, the claim that
Gromov-Witten invariants of any toric Calabi-Yau 3-fold coincide with the
spectral invariants of its mirror curve.Comment: 1+37 page
Quantum coherent control of highly multipartite continuous-variable entangled states by tailoring parametric interactions
The generation of continuous-variable multipartite entangled states is
important for several protocols of quantum information processing and
communication, such as one-way quantum computation or controlled dense coding.
In this article we theoretically show that multimode optical parametric
oscillators can produce a great variety of such states by an appropriate
control of the parametric interaction, what we accomplish by tailoring either
the spatio-temporal shape of the pump, or the geometry of the nonlinear medium.
Specific examples involving currently available optical parametric oscillators
are given, hence showing that our ideas are within reach of present technology.Comment: 14 pages, 5 figure
Pion condensation of quark matter in the static Einstein universe
In the framework of an extended Nambu--Jona-Lasinio model we are studying
pion condensation in quark matter with an asymmetric isospin composition in a
gravitational field of the static Einstein universe at finite temperature and
chemical potential. This particular choice of the gravitational field
configuration enables us to investigate phase transitions of the system with
exact consideration of the role of this field in the formation of quark and
pion condensates and to point out its influence on the phase portraits. We
demonstrate the effect of oscillations of the thermodynamic quantities as
functions of the curvature and also refer to a certain similarity between the
behavior of these quantities as functions of curvature and finite temperature.
Finally, the role of quantum fluctuations for spontaneous symmetry breaking in
the case of a finite volume of the universe is shortly discussed.Comment: RevTex4; 15 pages, 10 figure
Evaluation of tumor markers carcinoembryonic antigen, cytokeratin 19 fragment and cancer-associated antigen 72-4 in neoplastic and non-neoplastic canine effusions differentiation
Incidence, predictors and clinical impact of permanent pacemaker insertion in women following transcatheter aortic valve implantation: insights from a prospective multinational registry
To describe the incidence, predictors, and clinical impact of permanent pacemaker insertion (PPI) following transcatheter aortic valve replacement (TAVR) in women. Background: Data on pacemaker insertion complicating TAVR in women are scarce. Methods: The Women''s International Transcatheter Aortic Valve implantation (WIN-TAVI) is a prospective registry evaluating the safety and efficacy of TAVR in women. We included patients without preprocedural pacemakers and divided them into two groups: (1) PPI and (2) no-PPI. We identified PPI predictors using logistic regression and studied its clinical impact on the Valve Academic Research Consortium (VARC)-2 efficacy and safety endpoints. Results: Out of 1019 patients, 922 were included in the analysis. Post-TAVR PPI occurred in 132 (14.3%) patients. Clinical and procedural characteristics were similar in both groups. Pre-existing right bundle branch block (RBBB) was associated with a high risk of post-TAVR PPI (OR 3.62, 95% CI 1.85–7.06, p < 0.001), while implantation of balloon-expandable prosthesis was associated with a lower risk (OR 0.47, 95% CI 0.30–0.74, p < 0.001). Post-TAVR PPI prolonged in-hospital stay by a median of 2 days (11 [9–16] days in PPI vs. 9 [7–14] days in no-PPI, p = 0.005), yet risks of VARC-2 efficacy and safety endpoints at 1 year were similar in both groups (adjHR 0.95, 95% CI 0.60–1.52, p = 0.84 and adjHR 1.22, 95% CI 0.83–1.79, p = 0.31, respectively). Conclusion: Pacemaker implantation following TAVR is frequent among women and is associated with pre-existing RBBB and valve type. PPI prolongs hospital stay, albeit without any significant impact on 1-year outcomes
Search for composite and exotic fermions at LEP 2
A search for unstable heavy fermions with the DELPHI detector at LEP is
reported. Sequential and non-canonical leptons, as well as excited leptons and
quarks, are considered. The data analysed correspond to an integrated
luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV
and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172
GeV and 161 GeV. The search for pair-produced new leptons establishes 95%
confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2,
depending on the channel. The search for singly produced excited leptons and
quarks establishes upper limits on the ratio of the coupling of the excited
fermio
Search for charginos in e+e- interactions at sqrt(s) = 189 GeV
An update of the searches for charginos and gravitinos is presented, based on
a data sample corresponding to the 158 pb^{-1} recorded by the DELPHI detector
in 1998, at a centre-of-mass energy of 189 GeV. No evidence for a signal was
found. The lower mass limits are 4-5 GeV/c^2 higher than those obtained at a
centre-of-mass energy of 183 GeV. The (\mu,M_2) MSSM domain excluded by
combining the chargino searches with neutralino searches at the Z resonance
implies a limit on the mass of the lightest neutralino which, for a heavy
sneutrino, is constrained to be above 31.0 GeV/c^2 for tan(beta) \geq 1.Comment: 22 pages, 8 figure
Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP
Promptly decaying lightest neutralinos and long-lived staus are searched for
in the context of light gravitino scenarios. It is assumed that the stau is the
next to lightest supersymmetric particle (NLSP) and that the lightest
neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector
at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of
the production of these particles is found. Hence, lower mass limits for both
kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is
found to be greater than 71.5 GeV/c^2. In the search for long-lived stau,
masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10
to 150 \eVcc . Combining this search with the searches for stable heavy leptons
and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc
may be set for the stau mas
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