共查询到20条相似文献,搜索用时 0 毫秒
1.
A. Szereszewski J. Tafel M. Jakimowicz 《International Journal of Theoretical Physics》2012,51(5):1360-1369
Symmetry transformations in a space of D-dimensional vacuum metrics with D?3 commuting Killing vectors are studied. We solve directly the Einstein equations in the Maison formulation under additional assumptions. We show that the Reissner-Nordström solution is related by the symmetry transformation to a particular case of the 5-dimensional Gross-Perry metric and the 5-dimensional plane wave solution is related to the Gross-Perry-Sorkin metric. 相似文献
2.
Xiang Liu Zheng-Tao Wei Xue-Qian Li 《The European Physical Journal C - Particles and Fields》2009,59(3):683-689
To test the validity of perturbative QCD (pQCD) and investigate its range of application, one should look for a suitable process.
B→J/ψ
D is a promising candidate. The linear momentum of the products is relatively small, so that there may exist a region where
exchanged gluons are soft and the perturbative treatment may fail, so that the non-perturbative effect would be significant.
We attribute such non-perturbative QCD effects to the long-distance final-state interaction (FSI) which is estimated in this
work. We find that the contribution from the FSI to the branching ratio is indeed sizable and may span the rather wide range
of 10−6∼10−5 and cover a region where the pQCD prediction is of the same order. A more accurate measurement of its branching ratio may
provide important information about the application region of pQCD and help to clarify the picture of inelastic rescattering
(i.e. FSI), which is generally believed to play an important role in B decays. 相似文献
3.
MANSI DHURIA 《Pramana》2016,86(2):245-253
A phenomenological model is presented which can be obtained as a local Swiss-Cheese Calabi–Yau string-theoretic compactification with a mobile D3- and fluxed stacks of wrapped D7-branes. It provides a natural realization of (reversed) μ-split-like supersymmetry wherein the squarks, sleptons, gauginos, higgsino and one of the Higgs doublets are very heavy while with some fine tuning, it is possible to obtain another light Higgs of mass 125 GeV. We discuss the role of the heavy quarks /sleptons and the light Higgs in (i) obtaining long-lived gluinos (a natural consequence of split SUSY), (ii) verifying that the NLSP decays to the gravitino LSP respects the BBN constraints with the lifetime of the LSP (gravitino) coming out to be of the order or larger than the age of the Universe, (iii) getting gravitino relic abundance of around 0.1 and (iv) obtaining electronic EDM close to the experimental upper bounds. 相似文献
4.
5.
6.
Bastian Kubis Sebastian P. Schneider 《The European Physical Journal C - Particles and Fields》2009,62(3):511-523
Strong final-state interactions create a pronounced cusp in η′→η
π
0
π
0 decays. We adapt and generalize the non-relativistic effective field theory framework developed for the extraction of π
π scattering lengths from K→3π decays to this case. The cusp effect is predicted to have an effect of more than 8% on the decay spectrum below the π
+
π
− threshold. 相似文献
7.
Vi-Nham?Tram Fran?ois?Arleo 《The European Physical Journal C - Particles and Fields》2009,61(4):847-852
Interpreting the J/ψ suppression reported in nucleus–nucleus collisions at SPS and RHIC requires a quantitative understanding of cold nuclear-matter
effects, such as the inelastic rescattering of J/ψ states in nuclei or the nuclear modification of parton densities. With respect to our former Glauber analysis, we include
in the present work the new PHENIX d–Au measurements, and we analyze as well all existing data using the EPS08 nuclear parton densities recently released. The
largest suppression reported in the new PHENIX analysis leads in turn to an increase of σ
J/ψN from 3.5±0.3 to 5.4±2.5 mb using the PDF of the proton. The stronger x-dependence of the G
A
/G
p
ratio in EPS08 as compared to e.g. EKS98 shifts the cross section towards larger values at fixed-target energies (x
2∼0.1), while decreasing somehow the value extracted at RHIC (x
2∼10−2). 相似文献
8.
The process γ*γ → σ is investigated in the framework of the SU(2)×SU(2) chiral NJL model. The form factor of the process is derived for arbitrary virtuality of γ* in the Euclidean kinematic domain. The asymptotic behavior of this form factor resembles the asymptotic behavior of the γ*γ → π form factor. 相似文献
9.
10.
Bochao?Liu Markus?Büscher Feng-Kun?Guo Christoph?Hanhart Ulf-G.?Mei?ner 《The European Physical Journal C - Particles and Fields》2009,63(1):93-99
We investigate the interplay between crossed channel final state interactions and the constraints from two-particle unitarity
for the reactions J/ψ→V
π
π and
VK[`(K)]VK\bar{K}
, where V is either ω or φ. Using a model where the parameters are largely constrained by other sources, we find that, although small, crossed channel
final state interaction can influence the amplitudes considerably, in special areas of phase space. These results cast doubt
on the inapplicability of unitarity constraints on production amplitudes as recently claimed in the literature. 相似文献
11.
12.
The rare decay \(B\rightarrow {K^{*}}\ell ^+\ell ^-\) is a very significant mode to search for physics beyond the Standard Model (SM). The mode provides a very rich spectrum of observables obtained from the angular distribution of its decay products. The recent LHCb measured values of these observables are used to conclude an evidence of right-handed currents at the kinematic endpoint of this decay mode. As the conclusion is drawn at the maximum dilepton invariant mass square (\(q^2\)) kinematic endpoint, it relies only on heavy quark symmetries where it is valid without significant corrections. 相似文献
13.
We establish some general theorems for the existence and nonexistence of ground state solutions of steady-state N coupled nonlinear Schrödinger equations. The sign of coupling constants β ij ’s is crucial for the existence of ground state solutions. When all β ij ’s are positive and the matrix Σ is positively definite, there exists a ground state solution which is radially symmetric. However, if all β ij ’s are negative, or one of β ij ’s is negative and the matrix Σ is positively definite, there is no ground state solution. Furthermore, we find a bound state solution which is non-radially symmetric when N=3. 相似文献
14.
M. Gadella M. L. Glasser L. M. Nieto 《International Journal of Theoretical Physics》2011,50(7):2144-2152
We study a one-dimensional singular potential plus two types of regular interactions: constant electric field and harmonic
oscillator. In order to search for the bound state energies, we shall use the Lippman-Schwinger Green function technique.
Another direct method will be mentioned for the harmonic oscillator. In the electric field case the unique bound state coincides
with that found in an earlier study as the field is switched off. For non-zero field the ground state is shifted and positive
energy “quasibound states” appear. The harmonic oscillator demonstrates the general result that for a symmetric potential
the odd states are not altered whereas the even states energies are lowered or raised accordingly as the delta perturbation
is attractive or repulsive. No states are created or annihilated. 相似文献
15.
Lorenzo Basso Alexander Belyaev Stefano Moretti Giovanni Marco Pruna Claire H. Shepherd-Themistocleous 《The European Physical Journal C - Particles and Fields》2011,71(4):1613
We present the Large Hadron Collider (LHC) discovery potential in the Z′ sector of a \(U(1)_{B\mbox{--}L}\) enlarged Standard Model (that also includes three heavy Majorana neutrinos and an additional Higgs boson) for \(\sqrt{s}=7\), 10 and 14 TeV centre-of-mass (CM) energies, considering both the \(Z'_{B\mbox{--}L}\rightarrow e^{+}e^{-}\) and \(Z'_{B\mbox{--}L}\rightarrow\mu^{+}\mu^{-}\) decay channels. The comparison of the (irreducible) backgrounds with the expected backgrounds for the DØ experiment at the Tevatron validates our simulation. We propose an alternative analysis that has the potential to improve the DØ sensitivity. Electrons provide a higher sensitivity to smaller couplings at small \(Z'_{B\mbox{--}L}\) boson masses than do muons. The resolutions achievable may allow the \(Z'_{B\mbox{--}L}\) boson width to be measured at smaller masses in the case of electrons in the final state. The run of the LHC at \(\sqrt{s}=7\) TeV, assuming at most \(\int\mathcal{L} \sim1\) fb?1, will be able to give similar results to those that will be available soon at the Tevatron in the lower mass region, and to extend them for a heavier M Z′. 相似文献
16.
S. P. Baranov A. V. Lipatov N. P. Zotov 《The European Physical Journal C - Particles and Fields》2011,71(4):1631
We investigate the inclusive photoproduction of J/ψ mesons at HERA within the framework of the k
T
-factorization QCD approach. Our study is based on the color singlet model supplemented with the relevant off-shell matrix
elements and the CCFM and KMR unintegrated gluon densities in a proton and in a photon. Both the direct and resolved photon
contributions are taken into account. Our predictions are compared with the recent experimental data taken by the H1 and ZEUS
collaborations. Special attention is put on the J/ψ polarization parameters λ and ν, which are sensitive to the production dynamics. 相似文献
17.
In the context of the so-called Gauss–Bonnet gravity, where the gravitational action includes function of the Gauss–Bonnet
invariant, we study cosmological solutions, especially the well-known ΛCDM model. It is shown that the dark energy contribution and even the inflationary epoch can be explained in the frame of
this kind of theories with no need of any other kind of component. Other cosmological solutions are constructed and the rich
properties that this kind of theories provide are explored. 相似文献
18.
E. G. Ferreiro F. Fleuret A. Rakotozafindrabe 《The European Physical Journal C - Particles and Fields》2009,61(4):859-864
We present a new approach to estimate the effect of gluon shadowing in nucleus + nucleus collisions and its consequences on
the J/ψ production yield. Using kinematical information available from the measured J/ψ production in proton + proton collisions at
GeV, we build a Glauber Monte Carlo code which takes into account shadowing in two alternative ways: multiple-scattering
corrections or Q
2 evolution of parton densities. We exploit the dependence of these different parameterizations to the J/ψ transverse momentum and we give the first predictions on the resulting p
T dependence of the nuclear modification factor in deuteron + gold collisions at the same energy. 相似文献
19.
The possibility of experimental study of the nuclear interaction of mesons with nucleons and nuclei is considered. 相似文献
20.
M. Janek V. P. Ladygin S. M. Piyadin Yu. V. Gurchin A. Yu. Isupov J. T. Karachuk A. N. Khrenov A. K. Kurilkin P. K. Kurilkin A. N. Livanov G. Martinska S. G. Reznikov G. Tarjanyiova A. A. Terekhin 《Physics of Particles and Nuclei Letters》2018,15(1):76-82
Calibration procedure of ΔE ? E detectors used in dp breakup reaction measurement in the framework of DSS project is discussed. Time information from all PMTs along with amplitude information and known energy values of pp quasi elastic reaction are used to find calibration coefficients for ΔE and E detectors. Calibration coefficients are used to recover deposited particle energies. ΔE vs. E plots, energies and missing mass spectra are compared with geant4 Monte Carlo simulation. Missing mass for particular physical configuration is calculated as a test of the calibration procedure quality. 相似文献