共查询到20条相似文献,搜索用时 843 毫秒
1.
Shi-Min Xu Xing-Lei Xu Hong-Qi Li 《International Journal of Theoretical Physics》2008,47(9):2436-2443
We construct eight operators for a four-particle system, namely one center-of-mass coordinate operator, three relative coordinate
operators, one total momentum operator and three mass-weighted relative momentum operators, and give common eigenvectors of
four compatible observables
, which are composed of four particles’ coordinate
and momentum
. By compatible we mean such observables can be simultaneously determined. Using the technique of integration within an ordered
product (IWOP) of operators, we prove that the common eigenvectors are complete and orthonormal, and hereby qualified for
making up a representation. 相似文献
2.
From existing hadron and heavy-ion collisions data on
central production we estimate the value of the percolation parameter at RHIC energies.Received: 13 November 2003, Published online: 26 May 2004PACS:
25.75.Dw Particle and resonance productionYu.M. Shabelski: Permanent address: Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg, Russia; 相似文献
3.
J. Ellis F. Moortgat G. Moortgat-Pick J. M. Smillie J. Tattersall 《The European Physical Journal C - Particles and Fields》2009,60(4):633-651
We study the potential observation at the LHC of CP-violating effects in stop production and subsequent cascade decays,
,
,
, within the Minimal Supersymmetric Standard Model. We study T-odd asymmetries based on triple products between the different
decay products. There may be a large CP asymmetry at the parton level, but there is a significant dilution at the hadronic
level after integrating over the parton distribution functions. Consequently, even for scenarios where large CP intrinsic
asymmetries are expected, the measurable asymmetry is rather small. High luminosity and precise measurements of masses, branching
ratios and CP asymmetries may enable measurements of the CP-violating parameters in cascade decays at the LHC. 相似文献
4.
《The European Physical Journal C - Particles and Fields》2004,37(4):421-431
The Pauli exclusion principle (PEP) has been tested for nucleons (n,p) in
and
nuclei, using the results of background measurements with the prototype of the Borexino detector, the Counting Test Facility (CTF). The approach consisted of a search for
, n, p and/or
s emitted in a non-Paulian transition of 1P- shell nucleons to the filled 1S
1/2 shell in nuclei. Similarly, the Pauli-forbidden
decay processes were searched for. Due to the extremely low background and the large mass (4.2 tons) of the CTF detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established:
,
,
,
,
and
, all at
C.L.Received: 18 June 2004, Published online: 1 October 2004PACS:
11.30.-j, 24.80. + y, 23.20.-g, 27.20. + nG. Bellini: SpokesmanL. Cadonati: Now at Massachusetts Institute of Technology, NW17-161, 175 Albany St. Cambridge, MA 02139O. Dadoun: Marie Curie fellowship at LNGS
Correspondence to: A. Derbin. On leave of absence from St. Petersburg Nuclear Physics Inst. - Gatchina, RussiaM. Deutsch: DeceasedR. Ford: No w at Sudbury Neutrino Observatory, INCO Creighton Mine, P.O.Box 159 Lively, Ontario, Canada, P3Y 1M3B. Freudiger: Marie Curie fellowship at LNGS. Now at Institute for Nuclear Physics, Forschungszentrum Karlsruhe, Postfach 3640, 76021 KarlsruheS. Gazzana: GLIMOSV.V. Kobychev: Now at Institute for Nuclear Research, Prospekt Nauki 47, MSP 03680, Kiev, UkraineG. Korga: On leave of absence from KFKI-RMKI, Konkoly Thege ut 29-33 H-1121 Budapest, HungaryC. Lendvai: Marie Curie fellowship at LNGSP. Lombardi: Detector installation managerA. Martemianov: DeceasedV. Muratova: On leave of absence from St. Petersburg Nuclear Physics Inst. - Gatchina, RussiaL. Niedermeier: Marie Curie fellowship at LNGSL. Papp: On leave of absence from KFKI-RMKI, Konkoly Thege ut 29-33 H-1121 Budapest, HungaryR.S. Raghavan: Present Address: Department of Physics, Virginia Polytechnic Institute and State University, Blacksburg VA 24061G. Ranucci: Project managerC. Salvo: Operational manager
Correspondence to: O. SmirnovA. Sonnenschein: Center for Cosmological Physics, University of Chicago, 933 E.56th St., Chicago, IL 60637 相似文献
5.
H.-U. Martyn 《The European Physical Journal C - Particles and Fields》2006,48(1):15-24
A study of various SUSY scenarios is presented in which the lightest supersymmetric particle is the gravitino and the next-to-lightest supersymmetric particle is a scalar tau with lifetimes ranging from seconds to years. Gravitinos are interesting dark matter candidates which can be produced in decays of heavier sparticles at the International Linear Collider (ILC), but remain undetected in direct searches of astrophysical experiments. We investigate the detection and measurement of metastable staus, which may be copiously produced at the ILC either directly or via cascade decays. A proper choice of the experimental conditions will allow one to collect large samples of s coming to rest in the calorimeters of the ILC detector and to study the subsequent decays . Detailed simulations show that the properties of the stau and the gravitino, such as mass and lifetime and mass, can be accurately determined at a future ILC and may provide direct access to the gravitational coupling, respectively Planck scale. 相似文献
6.
In the SUSY SO(10) GUT context, we study the exclusive processes
. Using the Wilson coefficients of the relevant operators including the new operators
which are induced by neutral Higgs boson (NHB) penguins, we evaluate some possible observables associated with these processes like the invariant mass spectrum (IMS), lepton pair forward-backward asymmetry (FBA), lepton polarization asymmetries etc. In this model the contributions from Wilson coefficients
, among new contributions, are dominant. Our results show that the NHB effects are sensitive to the FBA,
, and
of
decay, which are expected to be measured in B factories, the deviation of
in
can reach 0.1 from SM, which could be seen in B factories, and the average of the normal polarization
can reach several percent for
and it is 0.05 or so for
, which could be measured in the future super B factories and provide useful information to probe new physics and discriminate different models.Received: 30 October 2004, Published online: 9 March 2005 相似文献
7.
In this paper, we apply the method of “invariant eigen-operator” to study the Hamiltonian of harmonic oscillator with couplings
and derive their invariant eigen-operator. We first discuss decoupling of coupled harmonic oscillators with the two different
quality and frequencies. And then, we propose an operator Hamiltonian to describe the linear lattice chain with Born–von Karman
boundary condition. The vibrating spectrum is thus obtained. The results show that, for the system of coupled harmonic oscillators
by coordinate coupling or momentum coupling, the invariant eigen operator
of system always has the form of
or
. 相似文献
8.
B. C. Hiesmayr 《The European physical journal. Special topics》2008,159(1):79-84
Particle physics has become an interesting
testing ground for fundamental questions of quantum
mechanics (QM). The massive meson-antimeson systems are
specially suitable as they offer a unique laboratory to
test various aspects of particle physics (
violation,
violation, ...) as well to test
the foundations of QM (local realistic theories versus QM,
Bell inequalities, decoherence effects, quantum marking and
erasure concepts, ...).
We focus here on a surprising connection between the violation of a
symmetry in particle physics –the
symmetry
(
=charge conjugation,
=parity)– and
non-locality. This is achieved via Bell inequalities which
discriminate between local realistic theories and QM.
Further we present a decoherence model which can be tested
by accelerator experiments at the DAΦNE (Italy) and at the
KEK-B machine (Japan). We show that there is a simple connection
between a decoherence parameter and different measures of
entanglement, i.e., entanglement of formation and concurrence. In
this way the very basic mathematical and theoretical concepts about
entanglement can be confronted directly with experiments. Similar
decoherence models can also be tested for entangled photon systems
and single neutrons in an interferometer. 相似文献
9.
First measurements of
mesons production properties and their spin alignment in
charged current (CC) and neutral current (NC) interactions are presented. The analysis of the full data sample of the NOMAD
experiment is performed in different kinematic regions. For
and
mesons produced in
CC interactions and decaying into
we have found the following yields per event:
and
respectively, while for the
and
mesons produced in
interactions the corresponding yields per event are:
and
. The results obtained for the
parameter,
and
for
and
produced in
CC interactions, are compared to theoretical predictions tuned on LEP measurements in
annihilation at the
pole. For
mesons produced in
interactions the measured
parameter is
.
PACS 13.15.+g, 13.60.Le, 13.87.Fh, 13.88.+e, 14.40.Ev 相似文献
10.
《The European Physical Journal C - Particles and Fields》2007,50(2):269-281
A search for stop production in R-parity-violating supersymmetry has been performed in e+p interactions with the ZEUS detector at HERA, using an integrated luminosity of 65 pb-1. At HERA, the R-parity-violating coupling λ’ allows resonant squark production, . Since the lowest-mass squark state in most supersymmetry models is the light stop, , this search concentrated on production of , followed either by a direct R-parity-violating decay, or by the gauge decay to . No evidence for stop production was found and limits were set on λ’131 as a function of the stop mass in the framework of the minimal supersymmetric standard model. The results have also been
interpreted in terms of constraints on the parameters of the minimal supergravity model. 相似文献
11.
Liu Yong-Mei 《International Journal of Theoretical Physics》2009,48(8):2372-2378
In this paper, we apply the method of “invariant eigen-operator” to study the Hamiltonian of arbitrary number of coupled identical
oscillators and derive their invariant eigen-operator. The results show that, (1) for the system of arbitrary number of identical
harmonic oscillators by coordinate coupling or momentum coupling, the invariant eigen operator
of system always has the form of
or
; (2) the energy level gap of the system has two kinds of possibilities: one is that gap only related to ω that the frequency of oscillators; another one is that gap not only related to ω that the frequency of oscillators, but also related to the number of the coupling oscillators. 相似文献
12.
K.J. Ozeren W.J. Stirling 《The European Physical Journal C - Particles and Fields》2006,48(1):159-168
We study the QCD scattering amplitudes for and where q is a massive fermion. Using a particular choice of massive fermion spinor we derive compact expressions for the partial spin amplitudes for the 2→2 process. We then investigate the corresponding 2→3 amplitudes using the BCFW recursion technique. For the helicity conserving partial amplitudes we present new expressions, but we were unable to treat the helicity-flip amplitudes recursively, except for the case where all the gluon helicities are the same. We therefore evaluate the remaining partial amplitudes using standard Feynman diagram techniques. 相似文献
13.
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
14.
Yukai An Shiqi Wang Deqiang Feng Zhonghua Wu Jiwen Liu 《Applied Physics A: Materials Science & Processing》2014,115(3):823-828
$(\mathrm{In}_{1-x}\mathrm{Fe}_{x})_{2}\mathrm{O}_{3}$ $(x=0.07, 0.09, 0.16, 0.22, 0.31)$ films were deposited on Si (100) substrates by RF-magnetron sputtering technique. The influence of Fe doping on the local structure of films was investigated by X-ray absorption spectroscopy (XAS) at Fe K-edge and L-edge. For the $(\mathrm{In}_{1-x}\mathrm{Fe}_{x})_{2}\mathrm{O}_{3}$ films with $x=0.07, 0.09 \mbox{ and } 0.16$ , Fe ions dissolve into $\mathrm{In}_{2}\mathrm{O}_{3}$ and substitute for $\mathrm{In}^{3+}$ sites with a mixed-valence state ( $\mathrm{Fe}^{2+}/\mathrm{Fe}^{3+}$ ) of Fe ions. However, a secondary phase of Fe metal clusters is formed in the $(\mathrm{In}_{1-x}\mathrm{Fe}_{x})_{2}\mathrm{O}_{3}$ films with $x=0.22 \mbox{ and } 0.31$ . The qualitative analyses of Fe-K edge extended X-ray absorption fine structure (EXAFS) reveal that the Fe–O bond length shortens and the corresponding Debye–Waller factor ( $\sigma^{2}$ ) increases with the increase of Fe concentration, indicating the relaxation of oxygen environment of Fe ions upon substitution. The anomalously large structural disorder and very short Fe–O distance are also observed in the films with high Fe concentration. Linear combination fittings at Fe L-edge further confirm the coexistence of $\mathrm{Fe}^{2+}$ and $\mathrm{Fe}^{3+}$ with a ratio of ${\sim}3:2$ ( $\mathrm{Fe}^{2+}: \mathrm{Fe}^{3+}$ ) for the $(\mathrm{In}_{1-x}\mathrm{Fe}_{x})_{2}\mathrm{O}_{3}$ film with $x=0.16$ . However, a significant fraction ( ${\sim}40~\mbox{at\%}$ ) of the Fe metal clusters is found in the $(\mathrm{In}_{1-x}\mathrm{Fe}_{x})_{2}\mathrm{O}_{3}$ film with $x=0.31$ . 相似文献
15.
16.
In this Letter, we show the existence of a natural and projectively equivariant quantization map depending on a linear torsion-free connection for the spaces
of differential operators mapping p-forms into functions on an arbitrary smooth manifold M. We show how this result implies the existence over
of an sl
m+1-equivariant quantization for the spaces
.This revised version was published online in March 2005 with corrections to the cover date. 相似文献
17.
G. Gritzner J. Ammer K. Kellner V. Kavečanský M. Mihalik S. Maťaš M. Zentková 《Applied Physics A: Materials Science & Processing》2008,90(2):359-365
La0.67Pb0.33(Mn1-xCox)O3-δ ceramics with x=0, 0.01, 0.03, 0.06, 0.1 and 0.15 have been prepared in a two-step procedure. Precursor gels were made by
the wet chemical malic acid method. The gels were calcined and then converted into ceramics by heat treatment at 950 °C and
1000 °C in air. X-ray diffraction showed that the compounds were phase pure. The crystal structure symmetry of the compounds
was confirmed to be rhombohedral (space group R3̄c) for the whole investigated range of x. All compounds undergo a paramagnetic–ferromagnetic
phase transition between 335 K and 225 K. The basic magnetic characteristics such as the Curie temperature , the paramagnetic Curie temperature θ, the effective magnetic moment and the saturated magnetization decrease with increasing Co doping. The ferromagnetic transition is accompanied by an anomaly in the electrical resistance
for all compounds. The high-temperature insulator–metal transitions () do not coincide with the relevant . A large magnetoresistance peak of about 15% was observed for all compounds at .
PACS 72.80.Ga; 75.47.Lx; 75.60.Ej 相似文献
18.
B. F. Parsons K. E. Strecker D. W. Chandler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):15-20
In our previous work we investigated electronically non-adiabatic effects in
using crossed molecular beam scattering
coupled with velocity mapped ion imaging. The prior experiments placed
limits on the cross-section for electronically non-adiabatic spin-orbit
excitation
and electronically non-adiabatic spin-orbit
quenching
.
In the present work, we investigate
electronically non-adiabatic spin-orbit quenching for
which is the required first step for the
reaction of Cl* to produce ground state HCl+H products. In these
experiments we collide Cl (2P) with H2 at a series of fixed
collision energies using a crossed molecular beam machine with velocity
mapped ion imaging detection. Through an analysis of our ion images, we
determine the fraction of electronically adiabatic scattering in
Cl* +H2, which allows us to place limits on the cross-section for
electronically non-adiabatic scattering or quenching. We determine the following
quenching cross-sections σ quench(2.1 kcal/mol) = 26 ±
21 ?2, σ quench(4.0 kcal/mol) = 21 ±
49 ?2, and σ quench(5.6 kcal/mol) = 14 ±
41 ?2. 相似文献
19.
We study irreversible polymer adsorption from dilute solutions theoretically. Universal features of the resultant non-equilibrium layers are predicted. Two broad cases are considered, distinguished by the magnitude of the local monomer-surface sticking rate Q: chemisorption (very small Q) and physisorption (large Q). Early stages of layer formation entail single-chain adsorption. While single-chain physisorption times
are typically micro- to milli-seconds, for chemisorbing chains of N units we find experimentally accessible times
, ranging from seconds to hours. We establish 3 chemisorption universality classes, determined by a critical contact exponent: zipping, accelerated zipping and homogeneous collapse. For dilute solutions, the mechanism is accelerated zipping: zipping propagates outwards from the first attachment, accelerated by occasional formation of large loops which nucleate further zipping. This leads to a transient distribution
of loop lengths s up to a maximum size
after time t. By times of order
the entire chain is adsorbed. The outcome of the single-chain adsorption episode is a monolayer of fully collapsed chains. Having only a few vacant sites to adsorb onto, late-arriving chains form a diffuse outer layer. In a simple picture we find for both chemisorption and physisorption a final loop distribution
and density profile
whose forms are the same as for equilibrium layers. In contrast to equilibrium layers, however, the statistical properties of a given chain depend on its adsorption time; the outer layer contains many classes of chain, each characterized by a different fraction of adsorbed monomers f. Consistent with strong physisorption experiments, we find the f values follow a distribution
.Received: 13 January 2003, Published online: 8 July 2003PACS:
82.35.-x Polymers: properties; reactions; polymerization -
05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion -
68.08.-p Liquid-solid interfaces 相似文献
20.
In the present work, we have studied the structural, dielectric, and electrical properties of a series of nanosized $\mathrm{ZnAl}_{2-2x}\mathrm{Y}_{2x}\mathrm{O}_{4}$ ( $x = 0.00$ , 0.01, 0.02, 0.03, 0.04, 0.05, 0.07, and 0.10) system prepared by chemical coprecipitation method. Powder X-ray diffraction (XRD) was carried out to study the influence of $\mathrm{Y}^{3+}$ substitution on the crystal structure of these samples. High Resolution Transmission Electron Microscopy (HRTEM) images reveal the nanocrystalline nature of the samples. The Fourier Transform Infrared (FTIR) spectra confirmed the preference of $\mathrm{Y}^{3+}$ ions at the octahedral B site. The variation of dielectric constant and loss tangent (1 kHz to 1 MHz) at room temperature for all the samples show the normal behavior of spinel compounds. AC conductivity study reveals that the conduction is due to small polaron hopping. The electrical modulus analysis shows that nanocrystalline $\mathrm{ZnAl}_{2-2x}\mathrm{Y}_{2x}\mathrm{O}_{4}$ system exhibits non-Debye-type relaxation. The DC electrical resistivity measured in the temperature range 303–373 K was found to increase with temperature and yttrium content. 相似文献