共查询到20条相似文献,搜索用时 46 毫秒
1.
M. Weis P. Bartsch D. Baumann J. Bermuth A. M. Bernstein K. Bohinc R. Böhm M. Ding M. O. Distler I. Ewald J. M. Friedrich J. Friedrich M. Kahrau M. Kohl K. W. Krygier A. Liesenfeld H. Merkel P. Merle U. Müller R. Neuhausen M. M. Pavan Th. Pospischil M. Potokar G. Rosner H. Schmieden M. Seimetz S. Širca A. Wagner Th. Walcher 《The European Physical Journal A - Hadrons and Nuclei》2008,38(1):27-33
The differential cross-sections σ0 = σT + εσL , σLT , and σTT of electroproduction from the proton were measured from threshold up to an additional center-of-mass energy of 40MeV, at a value
of the photon four-momentum transfer of Q
2 = 0.05 GeV2/c2 and a center-of-mass angle of θ = 90° . By an additional out-of-plane measurement with polarized electrons σLT' was determined. This showed for the first time the presence of an imaginary part of the s -wave above the threshold, which is usually interpreted as a unitary cusp. The predictions of the Heavy Baryon Chiral Perturbation Theory
(HBChPT) are in disagreement with these data. On the other hand, the data are somewhat better predicted by the MAID phenomenological
model and are in good agreement with the dynamical model DMT. 相似文献
2.
V. A. Bednyakov Ju. A. Budagov A. V. Gladyshev D. I. Kazakov E. V. Khramov D. I. Khubua 《Physics of Atomic Nuclei》2009,72(4):619-637
Prospects for observation of a SUSY-like signal from two gluinos are investigated within a certain region of the mSUGRA parameter space, where the cross section of the two-gluino production
in pp-collisions at the LHC ( = 14 TeV) is estimated at a rather high level of 17.3 pb. In this so-called EGRET-preferred region, the lightest stable neutralinos
χ
10 can serve as cold-dark-matter particles and can naturally explain the excess of diffuse Galactic gamma rays observed by the
EGRET space apparatus. The -event selection relies on a clear signature when decay products of each gluino contain one b
pair, one or two l
pair(s) or one or two light q
pair(s), and a neutralino. Rather high transverse missing energy carried away by the two neutralinos is the essential signature
of the events using of which allows the relevant Standard Model background to be reduced significantly. Furthermore, distributions
of the reconstructed invariant masses of two opposite-charged-lepton or light-jet pairs produced by the χ
20 → χ
10
l
+
l
− and χ
20 → χ
10
q
three-body decays have kinematic end points which measure the difference between masses of χ
20 and χ
10. In particular, it was found that these signatures of selected processes demonstrate good prospects for discovery of gluinos
at the LHC. These signatures allow one to distinguish different mSUGRA parameters m
1/2 within the EGRET-preferred region (at a higher than 6σ confidence level with 300 fb−1 data).
The text was submitted by the authors in English. 相似文献
3.
A. A. Tolchennikov 《Russian Journal of Mathematical Physics》2008,15(1):128-139
For the kernel of the Laplace operator ΔΛ with potential Σ
j=1
k
c
j
δ
q
j
(x) on a manifold, (the operator is given by a Lagrangian plane Λ ⊂ ℂ
k
⊕ ℂ
k
), an isomorphism Γ: ker ΔΛ → Λ ∩ L is described, where L is a special Lagrangian plane (whose explicit form is evaluated). A similar assertion holds for the Laplace operator on a decorated graph; for such a graph (obtained by decorating a connected finite graph with n edges and v vertices) with “continuity” conditions, the inequality 1 ≤ dimker ≤ n − v + 2 is obtained. It is also proved that the quantity n − v + 1-dim ker cannot reduce when adding new edges and manifolds. The first terms of the expansion of Tr(exp(-tH
Λ)) are found.
Dedicated to the memory of V. A. Geyler 相似文献
4.
Dephasing in open quantum chaotic systems has been investigated in the limit of large system sizes to the Fermi wavelength
ratio, L/λF 〉 1. The weak localization correction g
wl to the conductance for a quantum dot coupled to (i) an external closed dot and (ii) a dephasing voltage probe is calculated
in the semiclassical approximation. In addition to the universal algebraic suppression g
wl ∝ (1 + τD/τϕ)−1 with the dwell time τD through the cavity and the dephasing rate τ
ϕ
−1
, we find an exponential suppression of weak localization by a factor of ∝ exp[−
/τϕ], where
is the system-dependent parameter. In the dephasing probe model,
coincides with the Ehrenfest time,
∝ ln[L/λF], for both perfectly and partially transparent dot-lead couplings. In contrast, when dephasing occurs due to the coupling
to an external dot,
∝ ln[L/ξ] depends on the correlation length ξ of the coupling potential instead of λF.
The text was submitted by the authors in English. 相似文献
5.
N. M. Panyunin 《Russian Journal of Mathematical Physics》2007,14(4):501-504
In the note, a Smolyanov-Shavgulidze model of infinite-dimensional superspace H
Λ = Λ0
H
0 ⊕ Λ1
H
1 corresponding to a Hilbert space H = H
0 ⊕ H
1 over a Hilbert superalgebra Λ = Λ0 ⊕ Λ1 is considered. Its relation to the Khrennikov superspace is discussed. Moreover, H
Λ is equipped with the structure of Hilbert superspace with an inner superproduct (·, ·)Λ. The supermeasures are defined as Λℂ
(∧H
1)-valued measures on H
0 (Λℂ stands for the complexification of Λ). The definition of the Fourier supertransform is similar to the ordinary one,
(y) =
μ(dz). It turns out that the values of the Fourier supertransform of a supermeasure on the subspace
= H
0 ⊕ Λ1
H
1 can be obtained by applying a certain operator to the values of the classical Fourier transform. The main result is the theorem
claiming that the Fourier supertransform of supermeasures is isometric on superspaces with zero even part (H
0 = {0}). As a corollary, we note that the operator of Fourier supertransform is injective. We also give necessary and sufficient
conditions for the countable additivity of cylindrical supermeasures in terms of continuity of their Fourier supertransforms
(an analog of the Minlos-Sazonov theorem). 相似文献
6.
We address the decay of the norm of weak solutions to the 2D dissipative quasi-geostrophic equation. When the initial data
θ0 is in L
2 only, we prove that the L
2 norm tends to zero but with no uniform rate, that is, there are solutions with arbitrarily slow decay. For θ0 in L
p
∩ L
2, with 1 ≤ p < 2, we are able to obtain a uniform decay rate in L
2. We also prove that when the norm of θ0 is small enough, the L
q
norms, for , have uniform decay rates. This result allows us to prove decay for the L
q
norms, for , when θ0 is in .
The second author was partially supported by NSF grant DMS-0600692. 相似文献
7.
Lixin Xu Wenbo Li Jianbo Lu 《The European Physical Journal C - Particles and Fields》2009,60(1):135-140
In this paper, the holographic dark-energy model is considered in Brans–Dicke theory, where the holographic dark-energy density
ρ
Λ
=3c
2
M
pl2
L
−2 is replaced by ρ
h=3c
2
Φ(t)L
−2. Here
is the time-variable Newton constant. With this replacement, it is found that no accelerated expansion for the universe will
be achieved when the Hubble horizon is taken to play the role of an IR cut-off. When the event horizon is adopted as the IR
cut-off, accelerated expansion for the universe is obtained. In this case, the equation of state of holographic dark energy,
w
h, takes the modified form
. In the limit α→0, the ‘standard’ holographic dark energy is recovered. In the holographic dark-energy dominated epoch, power-law and de
Sitter time-space solutions are obtained. 相似文献
8.
Itzhak Goldman 《International Journal of Theoretical Physics》1982,21(8-9):665-672
Dirac’s large number hypothesis (LNH), in the formG/G
0=HH
0
−1
, is applied to the matter-dominated cosmological era, using the framework of the scale covariant theory (Canuto et al., 1977).
We obtain explicit expressions forR andβ
a
as functions ofR
E
, whereR andR
E
are the scale factors of the cosmological Robertson-Walker metric, expressed in atomic and gravitational units, respectively,
andβ
a
is the ratio between the rates of gravitational and atomic clocks. The parameters in these expressions are
, the deceleration parameter in gravitational units, and
(t
0)H
0
−1
where
(t
0) is the present epoch value of the derivative ofβ
a
with respect to atomic time. We find that a necessary condition for the LNH to be compatible with a Robertson-Walker model
is that
(t
0)H
0
−1
≥
2
1
. The only experimental values for
(t
0) available at present are those based on the lengthening of the Moon’s period of revolution around the Earth, suggesting
0.86≥
(t
0)H
0
−1
≥0.21; the more promising technique of radar ranging to the inner planets has not yet produced a value for
(t
0). Using the lunar data, it follows that 0≤
≲0.42 corresponding to an open universe (k=−1). Closed models (k=1,
>1/2) are not compatible with the LNH since the required values of
(t
0)H
0
−1
are more than an order of magnitude above the observational upper limit.
Presented at the Dirac Symposium, Loyola University, New Orleans, 1981. 相似文献
9.
10.
Ts. Tsogbayar 《Physics of Particles and Nuclei Letters》2009,6(2):114-117
Asymptotic formulae of some expectation values related to the relativistic corrections in inverse powers of the internuclear
distance R for the lsσ
g
electron state of hydrogen molecular ion H2+ and the lsσ molecule-like state of antiprotonic helium atom He+
are obtained with the use of the first-order perturbation function. Using these asymptotic formulae, the relativistic correction
of order mα6 for these states in reciprocal powers of the internuclear distance R is derived to accuracy of
(R
−4).
The article is published in the original. 相似文献
11.
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
12.
M. Janek V. P. Ladygin L. S. Azhgirey T. Uesaka Yu. V. Gurchin M. Hatano K. Itoh A. Yu. Isupov J. -T. Karachuk H. Kato T. Kawabata V. A. Krasnov A. N. Khrenov A. S. Kiselev V. A. Kizka J. Kliman A. K. Kurilkin P. K. Kurilkin N. B. Ladygina A. N. Livanov Y. Maeda A. I. Malakhov V. Matousek M. Morhach J. Nishikawa Yu. K. Pilipenko T. Ohnishi H. Okamura S. M. Piyadin S. G. Reznikov T. Saito S. Sakaguchi H. Sakai N. Sakamoto S. Sakoda Y. Sasamoto Y. Satou K. Sekiguchi K. Suda M. A. Shikhalev A. Tamii I. Turzo N. Uchigashima T. A. Vasiliev K. Yako L. S. Zolin 《Physics of Atomic Nuclei》2008,71(9):1495-1501
The investigation of the spin structure of d, 3H, and 3He has been performed at the RIKEN acceleration research facility and VBLHE. Vector A
y
and tensor A
yy
, A
xx
, A
xz
analyzing powers for
d → 3Hen and
d → 3Hp are presented at 270 MeV. Themirror channels (3Hen and 3Hp) are comparedto each other in order to find possible manifestation of charge-symmetry breaking. The preliminary results on
the polarization observables for
d → 3Hp at 200MeV are also presented. The obtained data are compared with one-nucleon-exchange calculations.As a byproduct,
d → pX and
12C → pX breakup reactions are investigated at 140, 200, and 270MeV. The experimental data on
p elastic scattering were obtained at 270, 880, and 2000 MeV at the Nuclotron. The polarization of the deuteron beam was measured
at 270 MeV at the internal target station. The preliminary data on the vector A
y
and tensor A
yy
, A
xx
analyzing powers for the
p elastic scattering at 880 MeV are presented. The calculations on A
y
, A
yy
, and A
xx
analyzing powers for the
p elastic scattering at 880 MeV were performed in the framework of the multiple-scattering model.
The text was submitted by the authors in English. 相似文献
13.
A new solid substrate-room temperature phosphorescence (SS-RTP) method for the determination of trace manganese (II) has been
established. It bases on the fact that fullerol (R) emits strong and stable room temperature phosphorescence (RTP) on filter
paper substrate. H2O2 can oxidize R to cause the SS-RTP quenching. But manganese (II) can obstruct H2O2 to oxidize R, and enhance the RTP of R. α,α′-Bipyridine (Bipy) can sensitize the RTP. After adding Bipy, the ΔI
p enhances 7 times than that without Bipy. Under the optimum conditions, the linear dynamic range of this method is 0.016–1.12 pg spot−1 with a detection limit (L.D.) of 4.6 fg spot−1 ( is the absolute mass of Mn2+), and the regression equation of working curve is ΔI
p=25.20 + 63.55 (pg spot−1), n=6, r=0.9983. For 0.016 and 1.12 pg spot−1 Mn2+, RSDS are 4.3 and 4.8%, respectively (n=7). This method has been applied to the determination of trace manganese (II) in actual sample with high sensitivity and
good selection. And the reaction mechanism of SS-RTP is discussed. 相似文献
14.
《The European Physical Journal C - Particles and Fields》2008,58(4):531-541
The production of two high-p
T
jets in the interactions of quasi-real photons in e
+
e
− collisions at
from 189 GeV to 209 GeV is studied with data corresponding to an integrated e
+
e
− luminosity of 550 pb−1. The jets reconstructed by the k
⊥
-cluster algorithm are defined within the pseudo-rapidity range −1<η<1 and with jet transverse momentum, p
T
, above 3 GeV/c. The differential di-jet cross-section is measured as a function of the mean transverse momentum
of the jets and is compared to perturbative QCD calculations.
Deceased 相似文献
15.
Hyun Jae Yoo 《Journal of statistical physics》2007,126(2):325-354
Given a positive definite, bounded linear operator A on the Hilbert space
0≔l
2(E), we consider a reproducing kernel Hilbert space
+ with a reproducing kernel A(x,y). Here E is any countable set and A(x,y), x,y∊ E, is the representation of A w.r.t. the usual basis of
0. Imposing further conditions on the operator A, we also consider another reproducing kernel Hilbert space
− with a kernel function B(x,y), which is the representation of the inverse of A in a sense, so that
−⊃
0⊃
+ becomes a rigged Hilbert space. We investigate the ratios of determinants of some partial matrices of A and B. We also get a variational principle on the limit ratios of these values. We apply this relation to show the Gibbsianness
of the determinantal point process (or fermion point process) defined by the operator A(I+A)−1 on the set E.
2000 Mathematics Subject Classification: Primary: 46E22 Secondary: 60K35 相似文献
16.
Giovanni Landi 《Letters in Mathematical Physics》2006,75(2):187-200
We construct a model of spin-Hall effect on a noncommutative four sphere S
4
Θ with isospin degrees of freedom, coming from a noncommutative instanton, and invariance under a quantum group SO
θ. The corresponding representation theory allows to explicitly diagonalize the Hamiltonian and construct the ground state;
there are both integer and fractional excitations. Similar models exist on higher dimensional spheres S
Θ
N
and projective spaces
.
Dedicated to Rafael Sorkin with friendship and respect. 相似文献
17.
18.
A. G. Ramm 《Journal of statistical physics》2007,127(5):915-934
If A
q(β, α, k) is the scattering amplitude, corresponding to a potential , where D⊂ℝ3 is a bounded domain, and is the incident plane wave, then we call the radiation pattern the function , where the unit vector α, the incident direction, is fixed, β is the unit vector in the direction of the scattered wave,
and k>0, the wavenumber, is fixed. It is shown that any function , where S
2 is the unit sphere in ℝ3, can be approximated with any desired accuracy by a radiation pattern: , where ∊ >0 is an arbitrary small fixed number. The potential q, corresponding to A(β), depends on f and ∊, and can be calculated analytically. There is a one-to-one correspondence between the above potential and the density
of the number of small acoustically soft particles D
m⊂ D, 1≤ m≤ M, distributed in an a priori given bounded domain D⊂ℝ3. The geometrical shape of a small particle D
m is arbitrary, the boundary S
m of D
m is Lipschitz uniformly with respect to m. The wave number k and the direction α of the incident upon D plane wave are fixed. It is shown that a suitable distribution of the above particles in D can produce the scattering amplitude , at a fixed k>0, arbitrarily close in the norm of L
2(S
2× S
2) to an arbitrary given scattering amplitude f(α ', α), corresponding to a real-valued potential q∊ L
2(D), i.e., corresponding to an arbitrary refraction coefficient in D.
MSC: 35J05, 35J10, 70F10, 74J25, 81U40, 81V05, 35R30.
PACS: 03.04.Kf. 相似文献
19.
S. M. Bilenky 《Physics of Particles and Nuclei》2008,39(5):641-673
Phenomenological issues of CP violation in the quark sector of the Standard Model are discussed. We consider quark mixing in the SM, standard, and Wolfenstein
parametrization of the CKM mixing matrix and unitarity triangle. We discuss the phenomenology of CP violation in K
L
0 and B
d
0()-decays. The standard unitarity triangle fit of the existing data is discussed. In appendix A we compare the K
0 ⇆ , B
d,s
0 ⇆
, etc. oscillations with neutrino oscillations. In Appendix B we derive the evolution equation for the M − system in the Weisskopf-Wigner approximation.
The text was submitted by the author in English. 相似文献
20.
Isothermal remanent magnetization decay,M
r(t), and ‘in-field’ growth of zero-field-cooled magnetization,M
ZFC(t), with time have been measured over four decades in time at temperatures ranging from 0.25T
c to 1.25T
c (whereT
c is the Curie temperature, determined previously for the same sample from static critical phenomena measurements) for a nearly
ordered intermetallic compound Ni3Al, which is an experimental realization of a three-dimensional (d = 3) ferromagnet with weak quenched random-exchange disorder. None of the functional forms ofM
r(t) predicted by the existing phenomenological models of relaxation dynamics in spin systems with quenched randomness, but only
the expressions
and
closely reproduce such data in the present case. The most striking features of magnetic relaxation in the system in question
are as follows: Aging effects are absent in bothM
r
t andM
ZFC(t) at all temperatures in the temperature range covered in the present experiments. A cross-over in equilibrium dynamics from
the one, characteristic of a pured = 3 ferromagnet with complete atomic ordering and prevalent at temperatures away from Tc, to that, typical of ad = 3 random-exchange ferromagnet, occurs asT → Tc. The relaxation times τ1(T)(τ1
′(T)) and τ2(T)(τ2
′(T)) exhibit logarithmic divergence at critical temperatures
and
;
and
both increase with the external magnetic field strength,H, such that at any given field value,
. The exponent characterizing the logarithmic divergence in τ
1
′
(T) and τ
2
′
T possesses a field-independent value of ≃16 for both relaxation times. Of all the available theoretical models, the droplet
fluctuation model alone provides a qualitative explanation for some aspects of the present magnetic relaxation data 相似文献