共查询到20条相似文献,搜索用时 15 毫秒
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2.
Zhang-Yu Nie Rong-Gen Cai Xin Gao Li Li Hui Zeng 《The European Physical Journal C - Particles and Fields》2015,75(11):559
In a previous paper (Nie et al. in JHEP 1311:087, arXiv:1309.2204 [hep-th], 2013), we presented a holographic s \(+\) p superconductor model with a scalar triplet charged under an SU(2) gauge field in the bulk. We also study the competition and coexistence of the s-wave and p-wave orders in the probe limit. In this work we continue to study the model by considering the full back-reaction. The model shows a rich phase structure and various condensate behaviors such as the “n-type” and “u-type” ones, which are also known as reentrant phase transitions in condensed matter physics. The phase transitions to the p-wave phase or s \(+\) p coexisting phase become first order in strong back-reaction cases. In these first order phase transitions, the free energy curve always forms a swallow tail shape, in which the unstable s \(+\) p solution can also play an important role. The phase diagrams of this model are given in terms of the dimension of the scalar order and the temperature in the cases of eight different values of the back-reaction parameter, which show that the region for the s \(+\) p coexisting phase is enlarged with a small or medium back-reaction parameter but is reduced in the strong back-reaction cases. 相似文献
3.
Yu-Liang Yan Bao-Guo Dong Dai-Mei Zhou Xiao-Mei Li Hai-Liang Ma Ben-Hao Sa 《The European Physical Journal C - Particles and Fields》2010,67(3-4):405-409
The parton rescattering effect on the charged particle production in ultra-relativistic p+p collisions is studied by the parton and hadron cascade model PACIAE, based on PYTHIA. We have calculated charged particle pseudorapidity density at mid-rapidity and the pseudorapidity distribution in inelastic and non-single diffractive p+p collisions at $\sqrt{s}=200$ , 900, 5500, and 14000 GeV with the PYTHIA and PACIAE models. The calculated results for $\sqrt{s}=900$ GeV are well compared with the ALICE data. Comparing the PYTHIA results (without parton rescattering) with the PACIAE results (with parton rescattering), it turned out that the parton rescattering may play an important role and this effect increases with increasing CMS energy. 相似文献
4.
Pankaj Jain Satish D. Joglekar Subhadip Mitra 《The European Physical Journal C - Particles and Fields》2008,57(4):671-680
We compute the two photon exchange contributions to elastic scattering of polarized electrons from target protons. We use
a non-local field theory formalism for this calculation. The formalism maintains gauge invariance and provides a systematic
procedure for making this calculation. The results depend on one unknown parameter,
. We compute the two photon exchange correction to the ratio of electric to magnetic form factors extracted using polarization
transfer experiments. The correction is found to be small if
. However, for larger values of
, the correction can be quite significant. The correction to the polarization transfer results goes in the right direction
to explain their difference with the ratio measured by the Rosenbluth separation method. We find that the difference between
the two experimental results can be explained for a wide range of values of the parameter
. We also find that the corrections due to two photon exchange depend on the photon longitudinal polarization ε. Hence, we predict an ε dependence of the form factor ratio extracted using the polarization transfer technique. Finally, we obtain a limit on
by requiring that the non-linearity in ε dependence of the unpolarized reduced cross section is within experimental errors. 相似文献
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6.
Sukanta Dutta Ashok Goyal Mamta 《The European Physical Journal C - Particles and Fields》2009,63(2):305-315
We study the one-loop new physics effects to the CP even triple neutral gauge boson vertices γ
⋆
γ
Z, γ
⋆
Z
Z, Z
⋆
Z
γ and Z
⋆
ZZ in the context of Little Higgs models. We compute the contribution of the additional fermions in Little Higgs models in the
framework of direct product groups where [SU(2)×U(1)]2 gauge symmetry is embedded in SU(5) global symmetry and also in the framework of the simple group where SU(N)×U(1) gauge symmetry breaks down to SU(2)
L
×U(1). We calculate the contribution of the fermions to these couplings when T parity is invoked. In addition, we re-examine the MSSM contribution at the chosen point of SPS1a′ and compare with the SM
and Little Higgs models. 相似文献
7.
T. Anticic B. Baatar J. Bartke L. Betev H. Bia?kowska B. Boimska J. Bracinik V. Cerny O. Chvala J. Dolejsi V. Eckardt H. G. Fischer Z. Fodor E. G?adysz K. Kadija A. Karev V. Kolesnikov M. Kowalski M. Kreps M. Makariev A. Malakhov M. Mateev G. Melkumov A. Rybicki N. Schmitz P. Seyboth T. Susa P. Szymanski V. Trubnikov D. Varga G. Vesztergombi S. Wenig 《The European Physical Journal C - Particles and Fields》2010,68(1-2):1-73
New data on the production of charged kaons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The kaons are identified by energy loss in a large TPC tracking system. Inclusive invariant cross sections are obtained in intervals from 0 to 1.7 GeV/c in transverse momentum and from 0 to 0.5 in Feynman x. Using these data as a reference, a new evaluation of the energy dependence of kaon production, including neutral kaons, is conducted over a range from 3 GeV to $\mathrm{p}+\overline{\mathrm{p}}$ collider energies. 相似文献
8.
Paul Sorensen 《The European Physical Journal C - Particles and Fields》2009,61(4):829-833
Recent data from heavy ion collisions at RHIC show strong near-side correlations extending over several units of rapidity.
This ridge-like correlation exhibits an abrupt onset with collision centrality. In this talk, I argue that the centrality
and beam-energy dependence of these near-angle correlations could provide access to information about the Quark Gluon Plasma
phase boundary and the Equation of State of nuclear matter. A beam-energy-scan at RHIC will better reveal the true source
of these correlations and should be a high priority at RHIC. 相似文献
9.
M. Miyabe M. Oba H. Iimura K. Akaoka Y. Maruyama I. Wakaida 《Applied Physics A: Materials Science & Processing》2010,101(1):65-70
A cerium oxide sample was ablated by 2nd harmonic radiation of Nd:YAG laser at a power density of 0.1 GW/cm2. Time evolution of the ablation plume was investigated by laser absorption time-of-flight (TOF) measurement. It was found
that the ablated ionic plume in vacuum consisted of two components having different velocities whereas the ablated neutral
atoms had mainly a single component. The flow velocity perpendicular to the sample surface in vacuum was determined to be
3.5 km/s for neutral atoms, and 4.7 km/s and 9.3 km/s for singly charged ions. From the detailed plume evolution in ambient
atmosphere with several pressures we obtained some experimental conditions suitable for isotope analysis of atomic cerium. 相似文献
10.
Yichun Xu 《The European Physical Journal C - Particles and Fields》2009,62(1):187-190
We report the transverse momentum (p
T
) distributions for identified charged pions, protons and anti-protons using events triggered by high deposit energy in the
Barrel Electro-Magnetic Calorimeter (BEMC) from p+p collisions at
GeV. The spectra are measured around mid-rapidity (|y|<0.5) over the range of 3<p
T
<15 GeV/c with particle identification (PID) by the relativistic ionization energy loss (rdE/dx) in the Time Projection Chamber (TPC) of the Solenoidal Tracker at RHIC (STAR). The charged pion, proton and anti-proton
spectra at high p
T
are compared with published results from minimum bias triggered events and the Next-Leading-Order perturbative quantum chromodynamic
(NLO pQCD) calculations (DSS, KKP and AKK 2008). In addition, we present the particle ratios of π
−/π
+,
, p/π
+ and
in p+p collisions. 相似文献
11.
A. Bolshakova I. Boyko G. Chelkov D. Dedovitch A. Elagin M. Gostkin S. Grishin A. Guskov Z. Kroumchtein Yu. Nefedov K. Nikolaev A. Zhemchugov F. Dydak J. Wotschack A. De Min V. Ammosov V. Gapienko V. Koreshev A. Semak Yu. Sviridov E. Usenko V. Zaets 《The European Physical Journal C - Particles and Fields》2009,62(4):697-754
We report on double-differential inclusive cross-sections of the production of secondary protons and charged pions, in the
interactions with a 5% λ
abs thick stationary beryllium target, of proton and pion beams with momentum from ±3 GeV/c to ±15 GeV/c. Results are given for secondary particles with production angles 20° <θ<125°. 相似文献
12.
M. Hauer V. V. Begun M. I. Gorenstein 《The European Physical Journal C - Particles and Fields》2008,58(1):83-110
The aim of this paper is to introduce a new technique for the calculation of observables, in particular multiplicity distributions,
in various statistical ensembles at finite volume. The method is based on Fourier analysis of the grand canonical partition
function. A Taylor expansion of the generating function is used to separate contributions to the partition function in their
power in volume. We employ Laplace’s asymptotic expansion to show that any equilibrium distribution of multiplicity, charge,
energy, etc. tends to a multivariate normal distribution in the thermodynamic limit. A Gram–Charlier expansion additionally
allows for the calculation of finite volume corrections. Analytical formulas are presented for the inclusion of resonance
decay and finite acceptance effects directly into the partition function of the system. This paper consolidates and extends
previously published results of the current investigation into the properties of statistical ensembles. 相似文献
13.
D. Nodop J. Rothhardt S. H?drich J. Limpert A. Tünnermann 《Applied physics. B, Lasers and optics》2009,94(3):399-401
We present a Q-switched microchip laser emitting 1064-nm pulses as short as 100 ps synchronized to a cavity dumped femtosecond
laser emitting 800-nm pulses as short as 80 fs. The synchronization is achieved by presaturating the saturable absorber of
the microchip laser with femtosecond pulses even though both lasers emit at widely separated wavelengths. The mean timing
jitter is 40 ps and thus considerably shorter than the pulse duration of the microchip laser. 相似文献
14.
Carlo Cafaro 《International Journal of Theoretical Physics》2008,47(11):2924-2933
A new information-geometric approach to chaotic dynamics on curved statistical manifolds based on Entropic Dynamics (ED) is
proposed. It is shown that the hyperbolicity of a non-maximally symmetric 6N-dimensional statistical manifold ℳ
s
underlying an ED Gaussian model describing an arbitrary system of 3N degrees of freedom leads to linear information-geometric entropy growth and to exponential divergence of the Jacobi vector
field intensity, quantum and classical features of chaos respectively. 相似文献
15.
Deok Kyu Kim Kyeong Min Kim Choon Bae Park 《Applied Physics A: Materials Science & Processing》2010,98(4):913-917
A p-type ZnO thin film was prepared using arsenic diffusion via the ampoule-tube method. This was followed by fabrication
of a ZnO p–n homojunction using n-type ZnO and characterization of the device properties. The ZnO thin film exhibited p-type
characteristics, with a resistivity of 2.19×10−3 Ω cm, a carrier concentration of 1.73×1020/cm3, and a mobility of 26.7 cm2/V s. Secondary ion mass spectrometer analysis confirmed that in- and out-diffusion occurred simultaneously from the external
As source and the GaAs substrate. The device exhibited the rectification characteristics of a typical p–n junction; the forward
voltage at 20 mA was approximately 5.5 V. The reverse-bias leakage current was very low—0.1 mA for −10 V; the breakdown voltage
was −11 V. The ampoule-tube method for fabricating p-type ZnO thin films may be useful in producing ultraviolet ZnO LEDs and
other ZnO-based devices. 相似文献
16.
André Mischke 《The European Physical Journal C - Particles and Fields》2009,61(4):807-809
We report measurements of the azimuthal angular correlation distribution of heavy-quark decay electrons and open charmed mesons
in pp collisions at
GeV in the STAR experiment at RHIC. This measurement in combination with current theoretical model calculations allows to
extract the relative bottom contribution to the heavy-quark decay electrons, which is important for the interpretation of
the observed strong suppression of the high-p
T electron yield in central Au+Au collisions. 相似文献
17.
This paper focuses on the study of existence and uniqueness of distributional and classical solutions to the Cauchy Boltzmann problem for the soft potential case assuming S n?1 integrability of the angular part of the collision kernel (Grad cut-off assumption). For this purpose we revisit the Kaniel–Shinbrot iteration technique to present an elementary proof of existence and uniqueness results that includes the large data near local Maxwellian regime with possibly infinite initial mass. We study the propagation of regularity using a recent estimate for the positive collision operator given in (Alonso et al. in Convolution inequalities for the Boltzmann collision operator. arXiv:0902.0507 [math.AP]) , by E. Carneiro and the authors, that allows us to show such propagation without additional conditions on the collision kernel. Finally, an L p -stability result (with 1≤p≤∞) is presented assuming the aforementioned condition. 相似文献
18.
Arnaud Duperrin 《The European Physical Journal C - Particles and Fields》2009,59(2):297-334
The energy frontier is currently at the Fermilab Tevatron accelerator, which collides protons and antiprotons at a center-of-mass energy of 1.96 TeV. The luminosity delivered to the CDF and DØ experiments has now surpassed the 4 fb?1. This paper reviews the most recent direct searches for Higgs bosons and beyond-the-standard-model (BSM) physics at the Tevatron. The results reported correspond to an integrated luminosity of up to 2.5 fb?1 of Run II data collected by the two Collaborations. Searches covered include the standard model (SM) Higgs boson (including sensitivity projections), the neutral Higgs bosons in the minimal supersymmetric extension of the standard model (MSSM), charged Higgs bosons and extended Higgs models, supersymmetric decays that conserve or violate R-parity, gauge-mediated supersymmetric breaking models, long-lived particles, leptoquarks, compositeness, extra gauge bosons, extra dimensions, and finally signature-based searches. Given the excellent performance of the collider and the continued productivity of the experiments, the Tevatron physics potential looks promising for discovery with the coming larger data sets. In particular, evidence for the SM Higgs boson could be obtained if its mass is light or near 160 GeV. The observed (expected) upper limits are currently a factor of 3.7 (3.3) higher than the expected SM Higgs boson cross section at m H =115 GeV and 1.1 (1.6) at m H =160 GeV at 95% C.L. 相似文献
19.
Luigi Cappiello Giancarlo D’Ambrosio 《The European Physical Journal C - Particles and Fields》2010,69(1-2):315-329
In holographic QCD the effects of gluonic condensate can be encoded in a suitable deformation of the 5D metric. We develop two different methods for the evaluation of first order perturbative corrections to masses and decay constants of vector resonances in 5D Hard-Wall models of QCD due to small deformations of the metric. They are extracted either from a novel compact form for the first order correction to the vector two-point function, or from perturbation theory for vector bound-state eigenfunctions: the equivalence of the two methods is shown. Our procedures are then applied to flat and to AdS 5D Hard-Wall models; we complement results of existing literature evaluating the corrections to vector decay constant and to two-pion–one-vector couplings: this is particularly relevant to satisfy the sum rules. We concentrate our attention on the effects for the Gasser–Leutwyler coefficients; we show that as in the Chiral Quark model, the addition of the gluonic condensate improves the consistency, the understanding and the agreement with phenomenology of the holographic model. 相似文献
20.
Luis N. Epele Huner Fanchiotti Carlos A. García Canal Vicente Vento 《The European Physical Journal C - Particles and Fields》2009,62(3):587-592
Magnetic monopoles have attracted the attention of physicists since the founding of the electromagnetic theory. Their search
has been a constant endeavor which was intensified when Dirac established the relation between the existence of monopoles
and charge quantization. However, these searches have been unsuccessful. We have recently proposed that monopolium, a monopole–antimonopole
bound state, so strongly bound that it has a relatively small mass, could be easier to find and become an indirect but clear
signature for the existence of magnetic monopoles. Here we extend our previous analysis for its production to two photon fusion
at LHC energies. 相似文献