共查询到20条相似文献,搜索用时 31 毫秒
1.
Yu. M. Andreev S. I. Bityukov N. V. Krasnikov A. N. Toropin 《Physics of Atomic Nuclei》2007,70(10):1717-1724
The LHC (CMS) discovery potential in the search for supersymmetry and lepton-flavor violation in neutralino decays using the
e
± μ∓ + E
T
miss
signature is studied. A detailed study is done for the CMS test points LM1-LM9. It is shown that, for the point LM1, it is
possible to detect lepton-flavor violation in neutralino decays with lepton-flavor-violating branching Br(
→ μ±
e
∓
) ≥ 0.04 Br(
→ e
+
e
−
, μ+ μ−
) for an integral luminosity of 10 fb−1. The discovery potential in the mSUGRA-SUSY scenario with tan β = 10, sgn(μ) = + in the (m
0, m
1/2) plane using the e
± μ∓ + E
T
miss
signature is determined.
The text was submitted by the authors in English. 相似文献
2.
O. B. Drennov 《Technical Physics》1999,44(2):166-170
The development of instability on a contact interface between steel objects is detected experimentally when it is loaded by
an oblique shock wave. It is shown that disturbances form in the stage of shock-wave loading (Δt<1μs, ΔU>1mm/μs) when the layers turn and the metals pass into a quasiliquid state. Then, at a relative slip velocity
the initial disturbances grow according to an exponential law and are “frozen” when the rarefaction wave reaches the contact
interface (when the contact zone of the metal “escapes” from the plastic state).
Zh. Tekh. Fiz. 69, 38–43 (February 1999) 相似文献
3.
Velocity-dependent forces varying as
(such as Weber force), here calledWeber-like forces, are examined from the point of view of energy conservation and it is proved that they are conservative if and only
ifγ=2μ. As a consequence, it is shown that gravitational theories employing Weber-like forces cannot be conservative and also yield
both the precession of the perihelion of Mercury as well as the gravitational deflection of light. 相似文献
4.
P. V. Fedorets M. Büscher V. P. Chernyshev S. N. Dymov V. Yu. Grishina C. Hanhart M. Hartmann V. Hejny V. Kleber H. R. Koch L. A. Kondratyuk V. P. Koptev A. E. Kudryavtsev P. Kulessa S. I. Merzliakov S. M. Mikirtychiants M. E. Nekipelov H. Ohm R. Schleichert H. Ströher V. E. Tarasov K. -H. Watzlawik I. Zychor 《Physics of Atomic Nuclei》2006,69(2):306-313
The reaction pp → dπ
+
η has been measured at a beam energy of T
p
= 2.65 GeV (p
p
= 3.46 GeV/c) using the ANKE spectrometer at COSY-Julich. The missing-mass distribution of the detected dπ
+ pairs exhibits a peak around the η mass on top of a strong background of multipion pp → dπ
+(nπ) events. The differential cross section d
4
σ/dΩd
dΩ
π
+
dp
d
dp
π
+ for the reaction pp → dπ
+
η has been determined model independently for two regions of phase space. Employing a dynamical model for the a
0
+
production allows one then to deduce a total cross section of σ(pp → da
0
+
→ dπ
+
η) = 1.1 ± 0.3stat ± 0.7syst μb for the production of π
+
η via the scalar a
0
+
(980) resonance and σ(pp → dπ
+
η) = 3.5 ± 0.3stat ± 1.0syst μb for the nonresonant production. Using the same model as for the interpretation of recent results from ANKE for the reaction
, the ratio of the total cross sections is
, which is in agreement with branching ratios in the literature.
The text was submitted by the authors in English. 相似文献
5.
《Physics of Atomic Nuclei》2001,64(5):891-901
Charmed-particle production in pp interactions at 70 GeV/c was studied with the SVD setup at the IHEP accelerator (Protvino). The experimental procedure used and the data-selection
methods are described. Data obtained by using a quickly cycling bubble chamber and a magnetic spectrometer are analyzed. The
number of inelastic-interaction events recorded in the chamber is 109000, with the charge multiplicity being n
ch/4. The corresponding statistics are 4.96 event/μb. Part of the events were recorded in the magnetic spectrometer. Three three-prong
decays of charged particles near the primary vertex are found on the films, two of these being recorded with the spectrometer.
All three are interpreted as D
− decays. Two neutral decays observed simultaneously in the chamber and in the spectrometer are interpreted as
decays. The total cross section for
production in the Feynman variable region −1<x
F<+1 is estimated at
. The cross-section values and the mean values 〈|x
F|〉 and 〈p⊥〉 for D mesons are compared with other experimental results in the energy range 58–800 GeV. The data of this experiment are compatible
with the cross-section estimates obtained in the beam-dump experiment at 70 GeV and with those predicted by perturbative QCD.
__________
Translated from Yadernaya Fizika, Vol. 64, No. 5, 2001, pp. 958–968.
Original Russian Text Copyright ? 2001 by Amaglobeli, Ardashev, Basiladze, Bogdanova, Bogolyubsky, Boguslavsky, Bulgakov,
Vischnevskaya, Volkov, Vorobiev, Galyaev, Gramenitsky, Grishina, Grishkevich, Ermolov, Zaitseva, Zapolsky, Zverev, Zotkin,
Ivanova, Karlov, Kireev, Kiryunin, Kozlov, kramarenko, Kubarovsky, Kuratashvili, Kurchaninov, Kutov, Larichev, Levitsky, Leflat,
Lyutov, Medved, Merkin, Minaenko, Moiseev, Nedev, Orfanitsky, Pleskach, A. Popov, V. Popov, Prosin, Ruzin, Rukovichkin, Rybnikov,
Ryadovikov, Samsonov, Selikov, Tevzadze, Tikhonova, Tolmachev, Topuria, Utochkin, Kholodenko, Khrenov, Tsyupa, Chekulaev,
Chiladze, Shabalina, Shafranov, Esakia.
The author represents the SVD Collaboration 相似文献
6.
S. Stave M. O. Distler I. Nakagawa N. Sparveris P. Achenbach C. Ayerbe Gayoso D. Baumann J. Bernauer A. M. Bernstein R. Böhm D. Bosnar T. Botto A. Christopoulou D. Dale M. Ding L. Doria J. Friedrich A. Karabarbounis M. Makek H. Merkel U. Müller R. Neuhausen L. Nungesser C. N. Papanicolas A. Piegsa J. Pochodzalla M. Potokar M. Seimetz S. Širca S. Stiliaris Th. Walcher M. Weis 《The European Physical Journal A - Hadrons and Nuclei》2006,30(3):471-476
To determine nonspherical angular-momentum amplitudes in hadrons at long ranges (low Q2), data were taken for the p(ˉe, e'p)π0 reaction in the Δ region at Q
2 = 0.060 (GeV/c)2 utilizing the magnetic spectrometers of the A1 Collaboration at MAMI. The results for the dominant transition magnetic dipole
amplitude and the quadrupole to dipole ratios at W = 1232 MeV are
, Re(
)%, and Re(
)%. These disagree with predictions of constituent quark models but are in reasonable agreement with lattice calculations
with nonlinear (chiral) pion mass extrapolations, with chiral effective field theory, and with dynamical models with pion
cloud effects. These results confirm the dominance, and general Q2 variation, of the pionic contribution at large distances. 相似文献
7.
Aluminum-lithium alloy 1420, which, after equal-channel angular pressing, has a grain size of about 3 μm, is shown to possess
superplasticity in a temperature range of T=320–395°C upon tension at a constant relative strain rate of 10−2–10−3 s−1. The axial deformation at fracture can exceed 1800%. The data processing at such large deformations should be carried out
using true strains ɛt and stresses σt. In the flow curve, a short stage of hardening is followed by a long softening stage. They can be described by the relation
with a constant exponent n≈2 and activation energies U≈1 eV for the softening stage and U≈1.4 eV for the hardening stage. The deformation is supposed to be controlled by grain-boundary sliding at the stage of softening
and by self-diffusion in the bulk of grains at the hardening stage.
__________
Translated from Fizika Tverdogo Tela, Vol. 43, No. 5, 2001, pp. 833–838.
Original Russian Text Copyright ? 2001 by Myshlyaev, Prokunin, Shpeizman. 相似文献
8.
S. A. Bonometto 《Il Nuovo Cimento C》1995,18(3):281-284
Summary If neutrino masses are related by the see-saw relation and
~2–3 eV, the τ-neutrino must be allowed to decay. Taking into account recent measurements of the cosmic expansion, which
yieldh≳0.8, the relativistic products of the decay of ντ can delay the equivalence as though it wereh≌0.3, soproviding a transfer function easy to reconcile with LSS data. This result is obtainable also if the actual final
contribution of νμ to the present cosmic density is as low as 4% of the critical density. Still keeping the above neutrino mass scale andh∼0.8, alternative choices of physical parameters lead to an earlier equivalence and to a more significant hot component. Altogether,
a whole class of models, with hot components characterized by 0.04 ≲ 0.2, can be devised, most of which can be expected to
be in reasonable agreement with data. 相似文献
9.
We examine the Wilson confining-area behavior for QCD(SU(
)) as described by a Witten effective reduced dynamics of constant-gauge fields. We show the model to be exactly soluble when
dynamical quark fields are added, together with fermion asymptotic freedom behavior. Additionally, we give arguments for the
triviality of the chiral-SU(N) non-abelian Thirring model at the t′Hooft limit of large number of colors
in the context of these constant-gauge-field reduced dynamics.
Received: 26 May 2004, Revised: 16 June 2005, Published online: 30 August 2005 相似文献
10.
INVESTIGATION OF EMPIRICAL LAWS FOR SUPERCONDUCTIVITY OF ALLOY AND COMPOUND SUPERCONDUCTORS 下载免费PDF全文
By studying the average effect of the electronegativity of alloy and compound superconductors, some empirical laws are found. The average value of the electronegativity of alloy superconductors \overlineχ is from 1.3 to 1.9, most of which is concentrated in the region 1.5<\overlineχ<1.8. The \overlineχ of many higher Tc superconductors is nearly 1.60. All these characteristics are similar to element superconductors. The average value of the electronegativity \overlineη of positive valence elements in oxide superconductors is from 1.3 to 1.6, and the average effect of an electronegativity of zero on every element \overlineζ is from 1.75 to 2.00. The mean of \overlineη and \overlineζ is from 1.5 to 1.8. When both \overlineη and \overlineζ are near the limit value (1.3 or 1.6 and 1.75 or 2.00), the material has a very low Tc, even is non-superconductive. The \overlineζ of other compound superconductors is either too high or too low, and the \overlineζ is too low so that the Tc of these superconductors is quite low. Studying the average effect of the electronegativity of non-superconducting compounds further confirms the laws. 相似文献
11.
We use different determinantal Hartree-Fock (HF) wave functions to calculate true variational upper bounds for the ground
state energy of N spin-half fermions in volume V
0, with mass m, electric charge zero, and magnetic moment μ, interacting through magnetic dipole-dipole interaction. We find that at high
densities when the average interparticle distance r
0 becomes small compared to the magnetic length r
m ≡ 2mμ2/ħ2, a ferromagnetic state with spheroidal occupation function n
↑(), involving quadrupolar deformation, gives a lower upper bound compared to the variational energy for the uniform paramagnetic
state or for the state with dipolar deformation. This system is unstable towards infinite density collapse, but we show explicitly
that a suitable short-range repulsive (hard core) interaction of strength U
0 and range a can stop this collapse. The existence of a stable equilibrium high density ferromagnetic state with spheroidal occupation
function is possible as long as the ratio of coupling constants Γcm ≡ (U
0
a
3/μ2) is not very small compared to 1.
相似文献
12.
Calculating the dielectric anisotropy of nematic liquid crystals: a reinvestigation of the Maier——Meier
theory 下载免费PDF全文
This paper investigates the average dielectric permittivity
(\overline ε ) in the Maier--Meier theory for calculating
the dielectric anisotropy (Δε) of nematic liquid
crystals. For the reason that \overline ε of nematics
has the same expression as the dielectric permittivity of the isotropic
state, the Onsager equation for isotropic dielectric was used to
calculate it. The computed \overline ε shows reasonable
agreement with the results of the numerical methods used in the
literature. Molecular parameters, such as the polarizability and its
anisotropy, the dipole moment and its angle with the molecular long
axis, were taken from semi-empirical quantum chemistry (MOCPAC/AM1)
modeling. The calculated values of Δε according
to the Maier--Meier equation are in good agreement with the experimental
results for the investigated compounds having different core
structures and polar substituents. 相似文献
13.
K. Terasaki 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):676-678
Although assigning D
s0
+(2317) to the I
3 = 0 component
of iso-triplet four-quark mesons is favored by experiments, its neutral and doubly charged partners have not yet been observed.
It is discussed why they were not observed in inclusive e
+
e
-→cˉ experiment and that they can be observed in B decays. 相似文献
14.
M. N. Vinoslavskiĭ P. A. Belevskii A. V. Kravchenko 《Journal of Experimental and Theoretical Physics》2006,102(3):417-430
The self-organization of an electron-hole plasma (EHP) heated by an electric field in pure p-Ge samples at T = 77 K has been studied experimentally. The derived current-voltage characteristics (CVCs) and the distributions of the electric
field and IR emission of the hot carriers along the samples show that the segments of a steep rise or the S-shaped segments of the CVCs in samples with n-p junctions are related to the formation of longitudinal thermal-diffusion autosolitons (AS‖); as a result, thin (d = 2–20 μm in diameter), melted-through current channels appear. Such AS‖ are formed at high EHP densities (n ≥ 1 × 1016 cm−3), when the electron-hole scattering is dominant, and at electron temperatures T
e
= (2–4.5)T
0 (T
0 is the lattice temperature). The saturation segments and the N-shaped segments in the CVCs are attributable to the generation of transverse thermal-diffusion high-field autosolitons (AS⊥) in the form of narrow strata with electric field strengths
= 1–20 kV cm−1. High-field AS⊥ are formed at EHP densities n = 5 × 1013−1 × 1016 cm−3, when the electron-phonon scattering is dominant, and at electron temperatures T
e
∼ Θ ≥ 5T
0 (Θ is the Debye temperature). The generated longitudinal and transverse autosolitons have high temperatures (T
e
≥ 1000 K) and reduced carrier densities and can exist simultaneously in different parts of the sample.
Original Russian Text ? M.N. Vinoslavskiĭ, P.A. Belevskii, A.V. Kravchenko, 2006, published in Zhurnal éksperimental’noĭ i
Teoreticheskoĭ Fiziki, 2006, Vol. 129, No. 3, pp. 477–492. 相似文献
15.
Yu.S. Surovtsev D. Krupa M. Nagy 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):409-416
In a combined analysis of the experimental data on the coupled processes ππ↦ππ, KˉK in the channel with I
G
J
PC = 0+0+ +, the various scenarios of these reactions (with different numbers of resonances) are considered. In a model-independent approach,
based only on analyticity and unitarity, a resonance is represented by a pole cluster (poles on the Riemann surface) of the
definite type that is defined by the state nature. The best scenario contains the resonances f
0(665) (with properties of the σ-meson), f
0(980) (with a dominant sˉs component), f
0(1500) (with a dominant flavour-singlet, e.g., glueball component) and the f
0(1710) (with a considerable sˉs component). If the f
0(1370) exists, it has a dominant sˉs component. The coupling constants of the observed states with the considered channels and the ππ and KˉK scattering lengths are obtained. The conclusion on the linear realization of chiral symmetry is drawn.
Received: 25 April 2002 / Accepted: 4 June 2002 / Published online: 26 November 2002
RID="a"
ID="a"e-mail: surovcev@thsun1.jinr.ru
RID="b"
ID="b"e-mail: krupa@savba.sk
RID="c"
ID="c"e-mail: fyzinami@nic.savba.sk
Communicated by V.V. Anisovich 相似文献
16.
Orbital responses to methyl sites in CnH2n+2 (n=1-6) are studied by B3LYP/TZVP based on the most stable geometries using the B3LYP/aug-cc-pVTZ method. Vertical ionization energies are produced using the SAOP/et-pVQZ model for the complete valence space. The highest occupied molecular orbital (HOMO) investigations indicate the p-electron profiles in methane, ethane, propane, and n-butane. By increasing the number of carbon-carbon bonds in lower momentum regions, the s, p-hybridized orbitals are built and display strong exchange and correlation interactions in lower momentum space (P≤0.50 a.u.). Meanwhile, the relative intensities of the isomers in lower momentum space show the strong bonding number dependence of the carbon-carbon bonds, meaning that more electrons have contributed to orbital construction. The study of representative valence orbital momentum distribution further confirms that the structural changes lead to evident electronic rearrangement over the whole valence space. An analysis based on the isomers reveals that the valence orbitals are isomer-dependent and the valence ionization energy experiences an apparent shift in the inner valence space. However, such shifts are greatly reduced in the outer valence space. Meanwhile, the opposite energy shift trend is found in the intermediate valence space. 相似文献
17.
M.P. Rekalo E. Tomasi-Gustafsson 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):575-581
The associative charm particles production in nucleon-nucleon collisions N + N↦Λc(Σc) + ˉD + N, is described in a general way and the spin and isospin structure of the corresponding matrix elements are derived. Using
an analogy with strange-particle (ΛK) production, the D-meson exchange model is considered in detail. Estimations of the energy behavior of the threshold cross-sections show a large
dependence on the form of the phenomenological hadron form factors and indicate that, at threshold, the cross-section is three
orders of magnitude smaller than for strange-particle production.
Received: 18 October 2002 / Accepted: 5 December 2002 / Published online: 18 March 2003
RID="a"
ID="a"Permanent address: National Science Center KFTI, 310108 Kharkov, Ukraine.
RID="b"
ID="b"e-mail: etomasi@cea.fr
Communicated by V.V. Anisovich 相似文献
18.
Low temperature laser absorption spectra of methane in the near-infrared at 1.65 μm for lower state energy determination 下载免费PDF全文
Direct absorption spectra of the 2v3 band of methane (CH4) from 6038 to 6050 cm-1 were studied at different low temperatures using a newly developed cryogenic cell in combination with a distributed feedback (DFB) diode laser. The cryogenic cell can operate at any stabilized temperature ranging from room temperature down to 100 K with temperature fluctuation less than ±1 K within 1 hour. In the present work, the CH4 spectra in the range of 6038-6050 cm-1 were recorded at 296, 266, 248, 223, 198, and 176 K. The lower state energy E″ and the rotational assignment of the angular momentum J were determined by a “2-low-temperature spectra method” using the spectra recorded at 198 and 176 K. The results were compared with the data from the GOSAT and the recently reported results from Campargue and co-workers using two spectra measured at room temperature and 81 K. We demonstrated that the use of a 2-low-temperature spectra method permits one to complete the E″ and J values missed in the previous studies. 相似文献
19.
Stability of the positively charged manganese centre in GaAs heterostructures examined theoretically by the effective mass approximation calculation near the Γ critical point 下载免费PDF全文
This paper describes an n-i-p-i-n model heterostructure with a manganese (Mn)-doped p-type base region to check the stability of a positively charged manganese AMn+ centre with two holes weakly bound by a negatively charged 3d5(Mn) core of a local spin S=5/2 in the framework of the effective mass approximation near the Γ critical point (k~0). By including the carrier screening effect, the ground state energy and the binding energy of the second hole in the positively charged centre AMn+ are calculated within a hole concentration range from 1 × 1016 cm-3 to 1 × 1017 cm-3, which is achievable by biasing the structure under photo-excitation. For comparison, the ground-state energy of a single hole in the neutral AMn0 centre is calculated in the same concentration range. It turns out that the binding energy of the second hole in the AMn+ centre varies from 9.27 meV to 4.57 meV. We propose that the presence of the AMn+ centre can be examined by measuring the photoluminescence from recombination of electrons in the conduction band with the bound holes in the AMn+ centre since a high frequency dielectric constant of varepsilon ∞ =10.66 can be safely adopted in this case. The novel feature of the ability to tune the impurity level of the AMn+ centre makes it attractive for optically and electrically manipulating local magnetic spins in semiconductors. 相似文献
20.
After surveying the experimental evidence for concentration coupling in the shear banding of wormlike micellar surfactant
systems, we present flow phase diagrams spanned by shear stress Σ (or strain rate ) and concentration, calculated within the two-fluid, non-local Johnson-Segalman (d-JS-φ) model. We also give results for
the macroscopic flow curves Σ(ˉ,ˉφ) for a range of (average) concentrations ˉφ. For any concentration that is high enough
to give shear banding, the flow curve shows the usual non-analytic kink at the onset of banding, followed by a coexistence
“plateau” that slopes upwards, dΣ/dˉ > 0. As the concentration is reduced, the width of the coexistence regime diminishes
and eventually terminates at a non-equilibrium critical point [Σc,ˉφc,ˉc]. We outline the way in which the flow phase diagram can be reconstructed from a family of such flow curves, Σ(ˉ,ˉφ), measured
for several different values of ˉφ. This reconstruction could be used to check new measurements of concentration differences
between the coexisting bands. Our d-JS-φ model contains two different spatial gradient terms that describe the interface between
the shear bands. The first is in the viscoelastic constitutive equation, with a characteristic (mesh) length l. The second is in the (generalised) Cahn-Hilliard equation, with the characteristic length ξ for equilibrium concentration-fluctuations.
We show that the phase diagrams (and so also the flow curves) depend on the ratio r ≡ l /ξ, with loss of unique state selection at r = 0. We also give results for the full shear-banded profiles, and study the divergence of the interfacial width (relative
to l and ξ) at the critical point.
Received: 20 December 2002 / Accepted: 24 April 2003 / Published online: 11 June 2003
RID="a"
ID="a"e-mail: physf@irc.leeds.ac.uk
RID="b"
ID="b"e-mail: p.d.olmsted@leeds.ac.uk 相似文献