共查询到20条相似文献,搜索用时 31 毫秒
1.
The BRAHMS measurement of proton-to-pion ratios in Au+Au and p+p collisions at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 62.4 GeV and $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 200 GeV is presented as a function of transverse momentum and collision centrality within the pseudorapidity range 0 ≤
η ≤ 3. The baryo-chemical potential, μ
B
, for the indicated data spans from μ
B
≈ 26 MeV ($
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
200 GeV, η ≈ 0) to μ
B
∼ 260 MeV ($
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 62.4 GeV, η ≈ 3) [1]. The p/πratio measured for Au+Au system at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
62.4 GeV, η ≈ 3 reaches astounding value of 8–10 at p
T
> 1.5 GeV/c. For these energy and pseudorapidity interval no centrality dependency of p/π ratio is observed. Moreover, the baryon-to-meson ratio of nucleus-nucleus data are consistent with results obtained for p+p
interactions. 相似文献
2.
Yu. S. Surovtsev T. Branz T. Gutsche V. E. Lyubovitskij 《Physics of Particles and Nuclei》2010,41(6):990-993
In a model-independent approach the data on ππ → ππ, K
$
\bar K
$
\bar K
, ηη, ηη′ in the I
G
J
PC
= 0+0++ channel and on the Kπ scattering in the $
I\left( {J^P } \right) = \frac{1}
{2}\left( {0^ + } \right)
$
I\left( {J^P } \right) = \frac{1}
{2}\left( {0^ + } \right)
channel are analyzed jointly for studying the status and QCD nature of the f
0- and the K*0-mesons. It is shown that in the 1500-MeV region, there are two states, wide (interpreted as a glueball) and narrow (q
$
\bar q
$
\bar q
). In the Kπ-scattering data analysis, the proof for the K*0(900) is given. 相似文献
3.
The Blume-Emery-Griffiths model with the dipole-quadrupole interaction ($
\ell = \frac{I}
{J}
$
\ell = \frac{I}
{J}
) has been simulated using a cellular automaton algorithm improved from the Creutz cellular automaton (CCA) on the face centered
cubic (fcc) lattice. The finite-size scaling relations and the power laws of the order parameter (M) and the susceptibility (χ) are proposed for the dipole-quadrupole interaction (ℓ). The dipole-quadrupole critical exponent
δχ has been estimated from the data of the order parameter (M) and the susceptibility (χ). The simulations have been done in the interval $
0 \leqslant \ell = \frac{I}
{J}0 \leqslant 0.01
$
0 \leqslant \ell = \frac{I}
{J}0 \leqslant 0.01
for $
d = \frac{D}
{J} = 0,k = \frac{K}
{J} = 0
$
d = \frac{D}
{J} = 0,k = \frac{K}
{J} = 0
and $
h = \frac{H}
{J} = 0
$
h = \frac{H}
{J} = 0
parameter values on a face centered cubic (fcc) lattice with periodic boundary conditions. The results indicate that the
effect of the ℓ parameter is similar to the external magnetic field (h). The critical exponent δℓ are in good agreement with the universal value (δ
h
= 5) of the external magnetic field. 相似文献
4.
T. Kojima 《Physics of Atomic Nuclei》2010,73(2):367-374
We study a free field realization of the elliptic quantum algebra Uq,p($
\widehat{sl_3 }
$
\widehat{sl_3 }
) for arbitrary level k. We give the free field realization of elliptic analog of Drinfeld current associated with Uq,p($
\widehat{sl_3 }
$
\widehat{sl_3 }
) for arbitrary level k. In the limit p → 0, q → 1 our realization reproduces Wakimoto realization for the affine Lie algebra
$
\widehat{sl_3 }
$
\widehat{sl_3 }
. 相似文献
5.
We present the measurement of directed flow (v
1) for the identified particles, namely, Λ, $
\bar \Lambda
$
\bar \Lambda
and K
s
0, as a function of rapidity and centrality in Au+Au collisions at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 200 GeV and 62.4 GeV. The measurement is based on the run IV data obtained by the STAR experiment at RHIC. In order to
enhance event plane resolution, we use tracks reconstructed from the Forward Time Projection Chambers (FTPCs), together with
the sideward deflection of spectator neutrons measured by the STAR’s Shower Maximum Detector at Zero Degree Calorimeters (ZDC-SMDs).
We find that for 200 GeV, proton and antiproton v
1 is less than 1%, the K
s
0
Λ, $
\bar \Lambda
$
\bar \Lambda
v
1 is less than 2%; for 62 GeV, proton v
1 is less than 1% and antiproton is less than 2%, v
1 for K
s
0, Λ, $
\bar \Lambda
$
\bar \Lambda
is less than 2% in Au+Au collisions at 200 GeV. 相似文献
6.
E. V. Gryzlova A. N. Grum-Grzhimailo A. I. Magunov S. I. Strakhova 《Optics and Spectroscopy》2010,109(1):59-65
Optical activity of xenon atoms in the vacuum UV range induced by circularly polarized laser light is studied theoretically.
The optical activity arises in the vicinity of the autoionizing state 5p
5(2
P
1/2)8s′$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
as a result of its coupling via the laser field with the discrete state 5p
5(2
P
3/2)7p
$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
. Polarization variations of the vacuum UV radiation upon its propagation through the atomic medium are calculated, and the
possibility of controlling this polarization is discussed. Manifestations of nonresonant coupling of the discrete state with
the broad autoionizing state 5p
5(2
P
1/2)6d′$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
induced by the overlap of the Rydberg autoionizing series in xenon are studied. 相似文献
7.
V. D. Maiorov I. S. Kislina E. G. Tarakanova 《Russian Journal of Physical Chemistry B, Focus on Physics》2017,11(1):37-48
Specific features of complexation in solutions of a strong dibasic acid in the H2SO4–2-pyrrolidone (Pyr) system (in the range of compositions of 0–100% H2SO4) are studied using multiple frustrated total internal reflection IR spectroscopy. The conclusions drawn on the structure of the complexes formed in such solutions are confirmed by quantum-chemical calculations of the mPyr · nH2SO4 (m, n = 1, 2) heteroassociates and by comparison of their calculated and measured vibrational spectra. It is found that, in the investigated solutions, four types of acid–base complexes, with various degrees of proton transfer in the OHO bridge, are formed: (AHA)– anions with quasi-symmetric H-bonds, solvated by acid molecules, or entering into the composition of PyrH+ · (AHA)– ion pairs; quasi-ion pairs with incomplete proton transfer to the base molecule of 1: 1 and 2: 2 compositions; and 2Pyr · H2SO4 complexes with two O–H···O bridges of molecular type. The main differences in the mechanisms of the acid–base interactions in the H2SO4–Pyr system as compared to the CH3SO3H–Pyr system result from the participation of two OH-groups of H2SO4 molecule in these interactions. Therefore, two types of quasi-ion pairs and complexes of 2Pyr · H2SO4 composition are formed. 相似文献
8.
A. I. Dmitriev V. M. Kaminski G. V. Lashkarev P. E. Butorin Z. D. Kovalyuk V. I. Ivanov A. I. Beskrovny 《Physics of the Solid State》2009,51(11):2342-2346
The neutron diffraction patterns have been analyzed for a layered single crystal and a powder of the γ-polytype of indium
selenide in the temperature range 10–300 K. In the temperature range 10–50 K, the excitation of bending vibrations due to
the charge density waves changes the phonon spectrum and gives rise to a negative thermal expansion in the plane of layers,
i.e., α‖c
= −2.2 × 10−6 K−1, which is characteristic of two-dimensional structures. The average (over the range T = 50–300 K) coefficients of thermal expansion along the principal crystallographic directions have been calculated: $
\bar \alpha _{ \bot c}
$
\bar \alpha _{ \bot c}
= 10.48 × 10−6 K−1 and $
\bar \alpha _{\parallel c}
$
\bar \alpha _{\parallel c}
= 12.97 × 10−6 K−1, which agree with the X-ray diffraction data previously obtained by the authors at T = 290 K. 相似文献
9.
The $
\mathcal{P}\mathcal{T}
$
\mathcal{P}\mathcal{T}
symmetry of the Coulomb potential and its solutions are studied along trajectories satisfying the $
\mathcal{P}\mathcal{T}
$
\mathcal{P}\mathcal{T}
symmetry requirement. It is shown that with appropriate normalization constant the general solutions can be chosen $
\mathcal{P}\mathcal{T}
$
\mathcal{P}\mathcal{T}
-symmetric if the L parameter that corresponds to angular momentum in the Hermitian case is real. $
\mathcal{P}\mathcal{T}
$
\mathcal{P}\mathcal{T}
symmetry is spontaneously broken, however, for complex L values of the form L = −1/2 + iλ. In this case the potential remains $
\mathcal{P}\mathcal{T}
$
\mathcal{P}\mathcal{T}
-symmetric, while the two independent solutions are transformed to each other by the $
\mathcal{P}\mathcal{T}
$
\mathcal{P}\mathcal{T}
operation and at the same time, the two series of discrete energy eigenvalues turn into each other’s complex conjugate. 相似文献
10.
This paper deals with the higher spin Dirac operator Q2,1 acting on functions taking values in an irreducible representation space for so(m) with highest weight $
(\tfrac{5}
{2},\tfrac{3}
{2},\tfrac{1}
{2},...,\tfrac{1}
{2})
$
(\tfrac{5}
{2},\tfrac{3}
{2},\tfrac{1}
{2},...,\tfrac{1}
{2})
. This operator acts as a toy model for generalizations of the classical Rarita—Schwinger equations in Clifford analysis.
Polynomial null solutions for this operator are studied in particular. 相似文献
11.
Yu. I. Romanov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(4):492-495
Electroweak (EW) and electromagnetic (EM) scattering of solar beryllium neutrinos by electrons are analyzed. An analysis of the influence of the mean-square charge
radius of an electron neutrino $
r_{\nu _e } = \sqrt {\left\langle {r_{_{\nu _e } }^2 } \right\rangle }
$
r_{\nu _e } = \sqrt {\left\langle {r_{_{\nu _e } }^2 } \right\rangle }
on differential and total cross sections is performed. The possibility of measuring the magnetic moment of an electron neutrino
(μv) on the basis of isolating its contribution to the section of the discussed processes is considered. 相似文献
12.
Paulo G. Castro Biswajit Chakraborty Zhanna Kuznetsova Francesco Toppan 《Central European Journal of Physics》2011,9(3):841-851
The $
\mathcal{N}
$
\mathcal{N}
-extended Supersymmetric Quantum Mechanics is deformed via an abelian twist which preserves the super-Hopf algebra structure
of its Universal Enveloping Superalgebra. Two constructions are possible. For even $
\mathcal{N}
$
\mathcal{N}
one can identify the 1D
$
\mathcal{N}
$
\mathcal{N}
-extended superalgebra with the fermionic Heisenberg algebra. Alternatively, supersymmetry generators can be realized as operators
belonging to the Universal Enveloping Superalgebra of one bosonic and several fermionic oscillators. The deformed system is
described in terms of twisted operators satisfying twist-deformed (anti)commutators. The main differences between an abelian
twist defined in terms of fermionic operators and an abelian twist defined in terms of bosonic operators are discussed. 相似文献
13.
The time-dependent and time-independent CP asymmetries $
A_{CP}^{B_q^0 \to f} \left( \tau \right)
$
A_{CP}^{B_q^0 \to f} \left( \tau \right)
and $
A_{CP}^{B_q^0 \to f} \left( {\hat s} \right)
$
A_{CP}^{B_q^0 \to f} \left( {\hat s} \right)
for rare semileptonic and radiative leptonic decays of B mesons are calculated by the method of helicity amplitudes. The sensitivity of CP asymmetries to various extensions of the Standard Model that have an operator basis that is identical to the operator basis
of the Standard Model is investigated. It is shown that, by combining information about the form of the charge lepton asymmetry
A
FB
at small values of the square of the invariant dilepton mass and information about the average value of the time-dependent
CP asymmetry, one can in principle determine the relative phases of the Wilson coefficients C
7γ
, C
9V
, and C
10A
in the effective Hamiltonian for b → {d, s}ℓ+ℓ− transitions. 相似文献
14.
M. A. Urusova V. M. Valyashko 《Russian Journal of Physical Chemistry B, Focus on Physics》2017,11(8):1322-1329
Supercritical phase equilibria in the ternary system K2SO4–KOH–H2O at 420–500°C and up to 130 MPa pressure with binary boundary subsystems of different types are studied. The binary subsystem of type 1 features no critical phenomena in saturated (l = g) aqueous solution and no phase separation (l1–l2) (KOH–H2O); the binary subsystem of type 2 is characterized by immiscibility of the liquid phase and has two critical end-points \(p(g = l-_{S_{K_{2}SO_{4}}})\) and \(Q(l_{1} = l_{2}-_{S_{K_{2}SO_{4}}})\) in saturated aqueous solution (K2SO4–H2O). The ternary system has two three-phase equilibria (g–l–s) and (l1–l2–s), separated by a two-phase supercritical fluid region \((fl-_{S_{K_{2}SO_{4}}})\), and two types of monovariant critical curves \((g=l-_{S_{K_{2}SO_{4}}})\) and \((l_{1}=l_{2}-_{S_{K_{2}SO_{4}}})\). The three-phase regions approach each other upon temperature increase up to the point where the two-phase supercritical equilibrium disappears, and the two mentioned monovariant critical curves are joined into a double homogeneous critical point \((g=l-_{S_{K_{2}SO_{4}}} \leftrightarrow l_{1} = l_{2}-_{S_{K_{2}SO_{4}}})\) at maximum temperature ~445°C and 51–52 MPa. 相似文献
15.
V. D. Maiorov G. I. Voloshenko N. B. Librovich 《Russian Journal of Physical Chemistry B, Focus on Physics》2011,5(2):271-277
The methanesulfonic acid (MSA)-diethylamine (DEA) binary liquid system is studied over the entire range of compositions at
30°C by using multiple frustrated total internal reflection IR spectroscopy. Solutions with acid: base equimolar ratio contain
only 1 : 1 ion pairs. Upon adding the acid, a MSA molecule abstracts an anion from the 1 : 1 complex to produce a protonated
DEA and an (H3C(O2)SO…H…OS(O2)CH3)− anion with a strong H bond: (C2H5)2(H)NH+ · OS(O2)CH3− + HOS(O2)CH3 ↔ (C2H5)2(H)NH+ + (H3C(O2)SO…H…OS(O2)CH3)−. This equilibrium is shifted to the left. The 1 : 1 complex is present in solutions even at an significant excess of the
acid. To protonate the complex, it is required at least two MSA molecules. Under conditions of an excess of the base, DEA
molecules do not solvate the 1 : 1 complex. The solution separates into two phases, composed of (C2H5)2(H)NH+ · OS(O2)CH3− complexes and pure DEA. 相似文献
16.
It was proved in the previous work that there must be a maximal possible accretion rate $
\dot M_{max}
$
\dot M_{max}
for a slim disk. Here we discuss how the value of $
\dot M_{max}
$
\dot M_{max}
depends on the two fundamental parameters of the disk, namely the mass of the central black hole M and the viscosity parameter α. It is shown that $
\dot M_{max}
$
\dot M_{max}
increases with decreasing α, but is almost independent of M if $
\dot M_{max}
$
\dot M_{max}
is measured by the Eddington accretion rate $
\dot M_{Edd}
$
\dot M_{Edd}
, which is in turn proportional to M. 相似文献
17.
S. G. Karshenboim 《Physics of Particles and Nuclei Letters》2009,6(6):450-454
Oscillations of neutral meson (K
0-$
\overline {K^0 }
$
\overline {K^0 }
, D
0-$
\overline {D^0 }
$
\overline {D^0 }
, and B
0-$
\overline {B^0 }
$
\overline {B^0 }
are extremely sensitive to the meson and antimeson energies at rest. This energy is determined as mc
2—with the corresponding inertial mass—and as the energy of gravitational interaction. Assuming that the CPT theorem is correct
for inertial masses and estimating the gravitational potential for which the largest contribution originates from the field
of the galaxy center, we obtain the estimate from experimental data on K
0-$
\overline {K^0 }
$
\overline {K^0 }
oscillations:
$
\left| {\left( {\frac{{m_g }}
{{m_i }}} \right)_{K^0 } - \left( {\frac{{m_g }}
{{m_i }}} \right)_{\overline {K^0 } } } \right| \leqslant 8 \times 10^{ - 13} , at C.L. = 90\%
$
\left| {\left( {\frac{{m_g }}
{{m_i }}} \right)_{K^0 } - \left( {\frac{{m_g }}
{{m_i }}} \right)_{\overline {K^0 } } } \right| \leqslant 8 \times 10^{ - 13} , at C.L. = 90\%
相似文献
18.
We have obtained inequality $
1 - {{\Delta \bar \tau } \mathord{\left/
{\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right.
\kern-\nulldelimiterspace} {\bar \tau }} < \left( {J \cdot V \cdot \bar \tau } \right)^{ - 1} < 1 + {{\Delta \bar \tau } \mathord{\left/
{\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right.
\kern-\nulldelimiterspace} {\bar \tau }}
$
1 - {{\Delta \bar \tau } \mathord{\left/
{\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right.
\kern-\nulldelimiterspace} {\bar \tau }} < \left( {J \cdot V \cdot \bar \tau } \right)^{ - 1} < 1 + {{\Delta \bar \tau } \mathord{\left/
{\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right.
\kern-\nulldelimiterspace} {\bar \tau }}
, where J is the frequency of homogeneous nucleation, V and $
\bar \tau
$
\bar \tau
are, respectively, volume and average lifetime of the superheated liquid, and $
{{\Delta \bar \tau } \mathord{\left/
{\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right.
\kern-\nulldelimiterspace} {\bar \tau }}
$
{{\Delta \bar \tau } \mathord{\left/
{\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right.
\kern-\nulldelimiterspace} {\bar \tau }}
is relative statistical error $
\bar \tau
$
\bar \tau
. Inequality appears to be a consequence of nucleation homogeneity and stability used at its deduction and taken in the theory
as initial and determinant assumption. Calculations with the use of experimental data for the boundaries of the attainable
superheating show that inequality is not satisfied. Thus, experimental data can not be considered a proof of the theory fundamentals. 相似文献
19.
H. Milani Moghaddam 《Pramana》2010,74(4):633-641
In the last decade, it was shown that the Liouville field theory is an effective theory of Dirac fermions in the random gauge
potential (FRGP). We show that the Dirac wave functions in FRGP can be written in terms of descendents of the Liouville vertex
operator. In the quasiclassical approximation of the Liouville theory, our model predicts that the localization length ξ scales with the energy E as $
\xi \sim E^{{{ - b^2 } \mathord{\left/
{\vphantom {{ - b^2 } {(1 + b^2 )^2 }}} \right.
\kern-\nulldelimiterspace} {(1 + b^2 )^2 }}}
$
\xi \sim E^{{{ - b^2 } \mathord{\left/
{\vphantom {{ - b^2 } {(1 + b^2 )^2 }}} \right.
\kern-\nulldelimiterspace} {(1 + b^2 )^2 }}}
, where b is the strength of the disorder. The self-duality of the theory under the transformation b → 1/b is discussed. We also calculate the distribution functions of t
0 =|ψ
0(x)|2, (i.e. p(t
0); ψ
0(x) is the ground state wave function), which behaves as the log-normal distribution function. It is also shown that in small
t
0, p(t
0) behaves as a chi-square distribution. 相似文献
20.
E. Braidot 《Indian Journal of Physics》2010,84(12):1771-1775
Early results from the Solenoidal Tracker At RHIC (STAR) using prototype forward calorimeters (FPD/FPD++) have shown that
in d+Au collisions at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 200 GeV a stronger suppression of forward π
0 yield is observed than would be expected from shadowing effects. Exploratory measurements and observations can be qualitatively
interpreted using the Color Glass Condensate (CGC) model to describe the colliding nucleus. A new detector, the Forward Meson
Spectrometer (FMS), has been built to measure forward pion and photon production to quantify gluon suppression at low x in heavy nuclei over a large range in x and p
T
. 相似文献
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