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1.
The "good" diquark is employed to study A+ baryons within a mass loaded flux tube model. The study indicates that all A+ baryons candidates in the 2008 review by the Particle Data Group (PDG) are well described in the mass loaded flux model. The quantum numbers JP of these A+ candidates are assigned. If Ac(2765)+ is an orbitally excited A+, it is likely the JP=3/2+one. If ∧c(2765)+ is an orbitally excited ∑c, there ought to be another JP=3/2+∧c+with mass ≈2770 MeV. In the model, there exists no JP=1/2+∧c+(≈2700)predicted in existing literature. Ac (2940)+ is very possible the orbitally excited baryon with 相似文献
2.
Kimball A. Milton Inés Cavero-Peláez Prachi Parashar K. V. Shajesh J. Wagner 《International Journal of Theoretical Physics》2011,50(4):963-973
The construction of PT\mathcal{PT}-symmetric quantum electrodynamics is reviewed. In particular, the massless version of the theory in 1+1 dimensions (the Schwinger
model) is solved. Difficulties with unitarity of the S-matrix are discussed. 相似文献
3.
We investigate the occurrence of Hunds rule magnetism in C
molecular ions, by computing the ground-state spin for all charge states n from -3 to +5. The two competing interactions, electron-vibration (e-v, including Jahn Teller, favoring low spin) and electron-electron (e-e, including Hund-rule exchange, favoring high spin), are accounted for based on previously computed ab initio coupling parameters. Treating the ion coordinates as classical, we first calculate and classify the static Jahn-Teller distorted states for all n, inclusive of both e-v and e-e effects. We then correct the adiabatic result by including the zero-point energy lowering associated with softening of vibrations at the adiabatic Jahn-Teller minima. Our overall result is that while, like in previous investigations, low-spin states prevail in negative ions, Hunds rule high spin dominates all positive C60
n+ ions. This suggests also that Hund-rule magnetism could arise in fullerene cation-based solid state compounds, particularly those involving C60
2+.Received: 17 April 2003, Published online: 22 September 2003PACS:
36.40.Cg Electronic and magnetic properties of clusters - 61.48.+c Fullerenes and fullerene-related materials (structure) - 71.20.Tx Fullerenes and related materials; intercalation compounds (electronic structure) - 75.75.+a Magnetic properties of nanostructures 相似文献
4.
The hadronic decays η,
↦3π and
↦ηππ are investigated within the framework of U(3) chiral effective field theory in combination with a relativistic coupled-channels approach. Final state interactions are
included by deriving s- and p-wave interaction kernels for meson-meson scattering from the chiral effective Lagrangian and iterating them in a Bethe-Salpeter
equation. Very good overall agreement with currently available data on decay widths and spectral shapes is achieved. 相似文献
5.
Qing-hai Wang 《International Journal of Theoretical Physics》2011,50(4):1005-1011
The relation between the P\ensuremath{\mathcal{P}}
T\ensuremath{\mathcal{T}} symmetry and Hermiticity is discussed. In the finite-dimensional linear space, any Hermitian matrix is a special case of
P\ensuremath{\mathcal{P}}
T\ensuremath{\mathcal{T}}-symmetric matrices. Explicit results in 2×2 are shown. The early belief that the P\ensuremath{\mathcal{P}}
T\ensuremath{\mathcal{T}}-symmetric quantum mechanics is a generalization of the conventional Hermitian quantum mechanics is confirmed. 相似文献
6.
The E2 algebra has three elements, J, u, and v, which satisfy the commutation relations [u,J]=iv, [v,J]=−iu, [u,v]=0. We can construct the Hamiltonian H=J
2+gu, where g is a real parameter, from these elements. This Hamiltonian is Hermitian and consequently it has real eigenvalues. However,
we can also construct the PT\mathcal{P}\mathcal{T}-symmetric and non-Hermitian Hamiltonian H=J
2+igu, where again g is real. As in the case of PT\mathcal{P}\mathcal{T}-symmetric Hamiltonians constructed from the elements x and p of the Heisenberg algebra, there are two regions in parameter space for this PT\mathcal{P}\mathcal{T}-symmetric Hamiltonian, a region of unbroken PT\mathcal{P}\mathcal{T} symmetry in which all the eigenvalues are real and a region of broken PT\mathcal{P}\mathcal{T} symmetry in which some of the eigenvalues are complex. The two regions are separated by a critical value of g. 相似文献
7.
M.J. Russcher 《The European Physical Journal C - Particles and Fields》2007,49(1):231-234
Results are presented of an ongoing analysis of direct photon production in =200 GeV deuteron-gold collisions (d+Au) with the STAR experiment at RHIC. A significant excess of direct photons is observed
near mid-rapidity (0<y<1) and found to be consistent with next-to-leading order pQCD calculations including the contribution
from fragmentation photons.
PACS 25.75.-q 相似文献
8.
T. Mannel B. D. Pecjak A. A. Pivovarov 《The European Physical Journal C - Particles and Fields》2011,71(4):1607
We use QCD sum rules to compute the matrix elements of the ΔB=2 operators appearing in the heavy-quark expansion of the width difference of the B
s
mass eigenstates. The main focus of our analysis is on the subleading operators R
2 and R
3, which appear at next-to-leading order in the 1/m
b
expansion. The matrix elements of these operators are already essential for precise phenomenology, but their calculation
in lattice QCD is lacking and the values given here provide a first estimate of their values. We conclude that the violation
of the factorization approximation for these matrix elements due to non-perturbative vacuum condensates is as low as 1–2%. 相似文献
9.
A. G. Knospe 《The European Physical Journal C - Particles and Fields》2009,62(1):223-227
Heavy-flavor semileptonic decays are expected to dominate the spectrum of non-photonic electrons produced from collisions
at the energies of the Relativistic Heavy Ion Collider. The non-photonic electron yield is suppressed by approximately a factor
of 5 in central Au + Au events at
GeV relative to p+p events with the same collision energy. Most theoretical models predict less non-photonic-electron suppression than is observed
experimentally. We present a preliminary measurement of the yield of non-photonic electrons in Cu + Cu events at
GeV, as well as the nuclear modification factor. 相似文献
10.
R. Belmont 《The European Physical Journal C - Particles and Fields》2009,62(1):243-248
In Run-7 of RHIC operations PHENIX has recorded over 5.4 billion minimum bias events, facilitating a detailed study of deuteron
and antideuteron production as a function of centrality and up to transverse momentum of p
T
=5 GeV/c. We present transverse momentum p
T
and transverse mass m
T
spectra, mean transverse momentum 〈p
T
〉, source parameters, particle ratios, and nuclear modification factor R
CP
. Deuteron and antideuteron spectra are compared to those of other identified particles and to hydrodynamical predictions. 相似文献
12.
J. Bielcik 《The European Physical Journal C - Particles and Fields》2007,49(1):375-378
The strong suppression of high pT hadrons observed at RHIC has led to the interpretation that energetic partons lose their energy via induced gluon radiation
in the hot and dense matter before fragmenting into hadrons. The study of heavy quark production can extend our understanding
of this scenario. Due to the dead cone effect, the suppression of heavy quark mesons at high pT is expected to be smaller than that observed for charged hadrons at the same energy. The measurement of non-photonic single
electrons up to high pT provides information on charm and beauty production. The semi-leptonic decays of D and B mesons are the dominant contribution
to the non-photonic electron spectra. The preliminary spectra from p+p, d+Au and Au+Au collisions at =200 GeV have been extracted for mid-rapidity non-photonic electrons in the range 1.5<pT (GeV/c)<10. The corresponding nuclear modification factors (RAA) are presented and show a large suppression in central Au+Au collisions, indicating an unexpectedly large energy loss for
heavy quarks in the hot and dense matter created at RHIC. This observed suppression is compared to recent theoretical models.
PACS 13.85.Qk; 13.20.Fc; 13.20.He; 25.75.Dw 相似文献
13.
Abdullah Algin 《International Journal of Theoretical Physics》2009,48(1):71-84
We discuss the algebras, representations, and thermodynamics of quantum group bosonic gas models with two different symmetries:
GL
p,q
(2) and
. We establish the nature of the basic numbers which follow from these GL
p,q
(2)- and
-invariant bosonic algebras. The Fock space representations of both of these quantum group invariant bosonic oscillator algebras
are analyzed. It is concisely shown that these two quantum group invariant bosonic particle gases have different algebraic
and high-temperature thermo-statistical properties. 相似文献
14.
de Florian Daniel Fidanza Nerina Hernández-Pinto Roger Mazzitelli Javier Habarnau Yamila Rotstein Sborlini Germán 《The European Physical Journal C - Particles and Fields》2013,73(4):1-5
We analyze a noncommutative model of BTZ spacetime based on deformation of the standard symplectic structure of phase space, i.e., a modification of the standard commutation relations among coordinates and momenta in phase space. We find a BTZ-like solution that is nonperturbative in the non-trivial noncommutative structure. It is shown that the use of deformed commutation relations in the modified non-canonical phase space eliminates the horizons of the standard metric. 相似文献
15.
We study frame properties of a matrix-valued wave packet system in the matrix-valued function space \(L^{2}(\mathbb {R}^{d}, \mathbb {C}^{s\times r})\), where the lower frame condition is controlled by a bounded linear operator \(\mathcal {K}\) on \(L^{2}(\mathbb {R}^{d}, \mathbb {C}^{s\times r})\) (lower \(\mathcal {K}\)-frame condition, in short). There are many differences between ordinary frames and \(\mathcal {K}\)-frames. The lower \(\mathcal {K}\)-frame condition for matrix-valued wave packet Bessel sequences in \(L^{2}(\mathbb {R}^{d},\mathbb {C}^{s\times r})\) in terms of operators; a trace functional associated with a bounded linear operator on \(L^{2}(\mathbb {R}^{d}, \mathbb {C}^{s\times r})\); and a series associated with a matrix-valued Bessel sequence is presented. It is shown that matrix-valued wave packet frames are stable under small perturbation with respect to wave packet window functions. 相似文献
16.
Alejandro?Ayala Eleazar?Cuautle Isabel?Domínguez Antonio?Ortiz Guy?Pai? 《The European Physical Journal C - Particles and Fields》2009,62(3):535-540
The experimental results on transverse momentum azimuthal hadron correlations at RHIC have opened a rich field for parton
energy loss analysis in heavy-ion collisions. Recently, a considerable amount of work has been devoted to study the shapes
of the “away-side” jet which exhibit an interesting and unexpected “double hump” structure not observed in the analogous treatment
of the pp data. Driven by the possibility that the latter result might just mean that such a structure exists already in the case of
pp collisions, but that its relative intensity could be small, here we use the Event Shape Analysis to show that it is possible
to identify and select well defined event topologies in pp collisions, among which a double hump structure for the away-side jet emerges. Using two shape parameters, the sphericity
in the transverse plane and the recoil to analyze a sample of PYTHIA generated pp collisions at
GeV, we show that this structure corresponds to two jets emitted in the backward hemisphere. Finally, we show that Q-PYTHIA
qualitatively reproduces the decrease in the yield of dijet events and the increase of the double hump structure in the away
side observed in heavy-ion collisions. The implications for the treatment of parton energy loss in heavy-ion collisions are
discussed. 相似文献
17.
An appropriate kind of curved Hilbert space is developed in such a manner that it admits operators of
- and
-differentiation, which are the analogues of the familiar covariant and D-differentiation available in a manifold. These tools are then employed to shed light on the space-time structure of Quantum
Mechanics, from the points of view of the Feynman ‘path integral’ and of canonical quantisation. (The latter contains, as
a special case, quantisation in arbitrary curvilinear coordinates when space is flat.) The influence of curvature is emphasised
throughout, with an illustration provided by the Aharonov-Bohm effect. 相似文献
18.
F. Benedosso 《The European Physical Journal C - Particles and Fields》2007,49(1):61-64
We present measurements of azimuthal correlations between photons (from π0 decay) and charged hadrons in d+Au collisions at =200 GeV. We use di-hadron correlations to study parton fragmentation in d+Au collisions at RHIC. Specifically, the near-side
and away-side peaks of the azimuthal angular difference distribution are used to measure the root-mean-squared (RMS) fragmentation
transverse momentum and the mean intrinsic parton transverse momentum . The measurements with leading photons are compared to results using leading charged particles.
PACS 25.75.-q 相似文献
19.
Rafibakhsh Shima Mehraban Hossein 《International Journal of Theoretical Physics》2021,60(10):4015-4021
International Journal of Theoretical Physics - We study the three-body baryonic decay $ \bar {B}^{0}\rightarrow {{\varLambda }}^{+}_{c} \bar {p} \pi ^{0}$ based on the factorization approach. The... 相似文献
20.
Yichun Xu 《The European Physical Journal C - Particles and Fields》2009,62(1):187-190
We report the transverse momentum (p
T
) distributions for identified charged pions, protons and anti-protons using events triggered by high deposit energy in the
Barrel Electro-Magnetic Calorimeter (BEMC) from p+p collisions at
GeV. The spectra are measured around mid-rapidity (|y|<0.5) over the range of 3<p
T
<15 GeV/c with particle identification (PID) by the relativistic ionization energy loss (rdE/dx) in the Time Projection Chamber (TPC) of the Solenoidal Tracker at RHIC (STAR). The charged pion, proton and anti-proton
spectra at high p
T
are compared with published results from minimum bias triggered events and the Next-Leading-Order perturbative quantum chromodynamic
(NLO pQCD) calculations (DSS, KKP and AKK 2008). In addition, we present the particle ratios of π
−/π
+,
, p/π
+ and
in p+p collisions. 相似文献