共查询到20条相似文献,搜索用时 31 毫秒
1.
L. V. Chkhaidze T. D. Djobava V. R. Garsevanishvili L. L. Kharkhelauri E. N. Kladnitskaya A. A. Kuznetsov G. O. Kuratashvili 《Physics of Atomic Nuclei》2004,67(7):1330-1337
The inclusive spectra of pions produced in CC and CTa collisions at a momentum of 4.2 GeV/c per nucleon are analyzed in terms of light-front variables ξ and ζ. The phase space of the secondary pions is divided into two parts with very different angular and momentum distributions. In one of these parts, the thermal equilibrium assumption seems to be in good agreement with the data. Corresponding temperatures T are extracted, and their dependence on (APAT)1/2 is studied: T decreases linearly with increasing (APAT)1/2. The results are compared with the predictions of the quark-gluon string model (QGSM). The QGSM satisfactorily reproduces the experimental data. 相似文献
2.
N G Deshpande 《Pramana》1993,41(1):249-259
The theory of loop induced rare B decays is reviewed. Both electromagnetic penguin processes and gluon mediated penguin processes are discussed. After consideringb→sy andb→se + e ? decays, purely hadronic modes likeB→K? are estimated. Constraints on the Higgs sector of SUSY theory fromb→sy is discussed. CP violation in charged B Decays is reviewed. 相似文献
3.
Tooraj Ghaffary 《International Journal of Theoretical Physics》2018,57(10):3066-3080
In this study by extending the recent suggested mechanisms to hadronization processes, the information loss for QCD matter in hadronic Rindler horizon is found. We notice that for all finite values of quark and gluon energies, all information from all hadronization processes experiences some degree of loss. Then the effect of hedonic Rindler horizon on three jet cross section is explored. It is found that the three jet cross section is rising at ycut =?0.0002 exhibits a turn-over at moderate value of ycut =?0.01 and then rapidly decreases as ycut increases. This model is consistent with OPAL data. Finally, different channels for producing Higgs boson near hadronic Rindler horizon are studied. It is shown that the cross section of Higgs boson produced via gluon fusion and quark interaction near a single Hadronic Rindler Horizon is much larger for higher center of mass energies. This is because an increase in the energy of hadronic Rindler horizon raises the temperature, thus intensifying the thermal radiation of QCD matter. 相似文献
4.
N. M. Agababyan V. V. Ammosov M. Atayan N. Grigoryan H. Gulkanyan A. A. Ivanilov Zh. Karamyan V. A. Korotkov 《Physics of Atomic Nuclei》2005,68(7):1160-1170
The influence of nuclear effects on the transverse momentum (pT) of neutrino-produced hadrons is investigated using the data obtained with the SKAT propane-freon bubble chamber irradiated in the neutrino beam (with E v =3–30 GeV) at the Serpukhov accelerator. It has been observed that the nuclear effects cause an enhancement of 〈p T 2 〉 of hadrons produced in the target fragmentation region at low invariant mass of the hadronic system (2 < W < 4 GeV) and at low energies transferred to the hadrons (2 < ν < 9 GeV). At higher W and ν, no influence of nuclear effects on 〈p T 2 〉 is observed. Measurement results are compared with predictions of a simple model, incorporating secondary intranuclear interactions of hadrons, which qualitatively reproduces the main features of the data. 相似文献
5.
The production of charmonium states in hadronic experiments is considered in the third order in the strong-coupling constant. It is shown that some significant difficulties that arise if such reactions are treated in the leading order can be overcome within this approach. In particular, the method applied here makes it possible to obtain transverse-momentum distributions of final-state charmonia. Also, the experimental observation of a χ c1 meson, which cannot be produced in the lowest order in α s , is then explained in a natural way. 相似文献
6.
Heavy quarkonium \((c\bar c,b\bar b)\) hadronic production at Tevatron (run I and run II) and LHC energies is considered in the framework of nonrelativistic quantum chromodynamics in the leading order with respect to α s and v using the quasi-multi-Regge kinematics approach. Fitting of p T spectra of different S and P wave heavy quarkonium states at Tevatron (run I and run II) energies is carried out. The obtained set of octet nonperturbative matrix elements is used for prediction of heavy quarkonium production at LHC energies. The results obtained in the framework of quasi-multi-Regge kinematics are compared with predictions of the collinear parton model. 相似文献
7.
I. P. Lokhtin A. V. Belyaev G. Ponimatkin E. Yu. Pronina G. Kh. Eiyubova 《Journal of Experimental and Theoretical Physics》2017,124(2):244-250
The phenomenological analysis and interpretation of experimental data from RHIC and LHC on the production of J/ψ and D mesons in heavy-ion collisions are performed within the two-component HYDJET++ model including the thermal and hard mechanisms of hadron production. It is shown that the thermal freeze-out of charmed mesons at RHIC energies occurs earlier than the thermal freeze-out of light hadrons (assumingly, simultaneously with chemical freeze-out), which indicates that J/ψ and D mesons are not in kinetic equilibrium with the formed hadronic matter. At the same time, a significant part of D mesons at LHC energies are in kinetic equilibrium with the formed thermalized matter, but J/ψ mesons are still characterized by early freeze-out. 相似文献
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The electron excitation of nucleon resonances is discussed both from the theoretical and from the experimental point of view. This discussion is based on a phenomenological approach that employs the conservation of the electromagnetic and vector-meson hadronic currents and the requirements of limiting chiral invariance. For the electron excitation of Jπ=1/2±,3/2±,5/2±,... nucleon resonances, the structure functions are defined in terms of Sachs transition form factors. The resulting resonance structure functions for l+N → l+R processes are used in parametrizing smooth (background) structure functions for l+N → l+X inelastic scattering. 相似文献
10.
The transverse-momentum spectra of direct J/ψ and ψ′ mesons in pp interactions at the Tevatron collider energy of \(\sqrt s = 1.8\) TeV are calculated on the basis of nonrelativistic QCD, the fragmentation model, the kT-factorization approach, and the standard parton model. The contribution of gluon fragmentation is shown to exceed the contribution of c-quark fragmentation both within the parton model and within the kT-factorization approach. Experimental data of the CDF Collaboration agree with the assumption that gluon fragmentation plays a dominant role in the \(Q\bar Q[^3 S_1 ,8]\) octet state, with the nonperturbative matrix element taking approximately equal values in the parton model and in the kT-factorization approach. 相似文献
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12.
We introduce the ‘stealth bosons’ S, light boosted particles with a decay \(S \rightarrow AA \rightarrow q \bar{q} q \bar{q}\) into two daughter bosons A, which subsequently decay into four quarks that are reconstructed as a single fat jet. Variables that measure the two-pronged structure of fat jets, which are used for diboson resonance searches in hadronic or semi-leptonic final states, classify the jets produced in stealth boson decays as QCD-like – actually, for these variables they may seem more background-like than the QCD background itself. The number of tracks in those jets can also be, on average, much higher than for the fat jets arising from the hadronic decay of boosted W and Z bosons. Therefore, these elusive particles are hard to spot in standard searches. Heavy resonances decaying into two such stealth bosons, or one plus a W / Z boson, could offer an explanation for the recurrent small excesses found in hadronic diboson resonance searches near an invariant mass of 2 TeV. 相似文献
13.
A. A. Bogdanov A. N. Vasiliev S. B. Nurushev A. Penzo M. F. Runzo O. V. Selugin M. N. Strikhanov 《Physics of Atomic Nuclei》2003,66(12):2189-2198
It is proposed to extract the total cross section for proton-proton (pp) interaction from the results obtained by measuring the analyzing power for elastic pp scattering in the region of Coulomb-nuclear interference. Contributions to the cross section are estimated that affect the accuracy in determining σ T (pp) and which originate from various sources, including single-spin-flip interactions. The applicability of the factor of merit to extracting σ T (pp) from experimental data is briefly discussed. It is concluded that, under some conditions, measurement of the analyzing power A N (t) may be a good approach to determining σ T (pp). 相似文献
14.
A. S. Malgin 《Journal of Experimental and Theoretical Physics》2017,125(5):728-740
The processes of the generation of cosmogenic neutrons (cg-neutrons) underground are considered. The neutrons produced by cosmic-ray muons in their interactions with matter are called cosmogenic. Deep-inelastic πA-collisions of pions in muon-induced hadronic showers are mainly their source at energies above 30 MeV. The characteristics of the energy spectrum for the generation of cg-neutrons have been determined by invoking the additive quark model of deep-inelastic soft processes and the mechanism for the interactions of high-energy nucleons in a nucleus. The three-component shape of the spectrum is explained, and the energy of the “knee” in the spectrum has been found to depend on the mass number A. The peculiarities of deep-inelastic πA-scattering lead to the conclusion that the spectrum of cg-neutrons steepens sharply at energies above 1 GeV. The calculated quantitative characteristics of the spectrum are compared with those obtained in measurements. 相似文献
15.
A. E. Dorokhov A. E. Radzhabov F. A. Shamakhov A. S. Zhevlakov 《Physics of Particles and Nuclei》2016,47(3):370-386
In the first part of the review we discuss the effective nonlocal approach in the quantum field theory. It concerns primary the historical retrospective of this approach, and than we concentrate on the interaction of matter particles (fermions and bosons) with the (abelian and nonabelian) gauge fields. In the second part of the review we consider the hadronic corrections (vacuum polarization) to the anomalous magnetic moment of the muon g - 2 factor discussed within the SUf(2) nonlocal chiral quark model. This is considered in the leading and, partially, in the next-to-leading orders (the effect of the fermion propagator dressing due to pion field) of expansion in small parameter 1/Nc (Nc is the number of colors in QCD). 相似文献
16.
V. T. Kim 《Physics of Particles and Nuclei Letters》2018,15(4):384-386
QCD evolution of nuclear structure functions at large x is reviewed within the an approach based on QCD factorization for hard processes and multiquark flucton model. In this approach, x > 1 region of the nuclear structure functions is intimately related with x < 1 region due to manifestation of quark and gluon degrees of freedom in nuclei. Properties of QCD evolution and observed EMC-ratio for nuclear structure functions at x < 1 result in an admixture of hard extra sea quark distribution. This extra nuclear quark sea provides a bump above unity for EMC-ratio at small x and becomes dominant in the nuclear quark sea for cumulative region x > 1. It leads to a striking prediction, confirmed by data, for the same spectrum slopes of all cumulative hadrons in nuclear fragmentation region. 相似文献
17.
N. O. Agasian 《Physics of Atomic Nuclei》2008,71(11):1967-1980
The norperturbative QCD vacuum at finite temperature in a external magnetic field is studied. Equations that relate nonperturbative QCD condensates at finite temperature to the thermodynamic pressure at T ≠ 0 and H ≠ 0 are obtained, and low-energy theorems are derived. The free energy of the QCD vacuum in the hadronic phase at H ≠ 0 is calculated, and expressions for the quark and gluon condensates are obtained. Various limiting cases for the behavior of the condensates at low and high temperatures and in weak and strong magnetic fields are investigated. A new interesting phenomenon that consists in the freezing of the quark condensate by a magnetic field is found. The character of spontaneous chiral-symmetry breaking in finite-temperature QCD in a magnetic field is studied. For this purpose, the Gell-Mann-Oakes-Renner formula relating the pion mass M π and the axial-vector coupling constant F π to the quark condensate is derived at T ≠ 0 and H ≠ 0. It is shown that this formula preserves its form at finite temperature after taking into account a magnetic field—that is, no additional terms independent of T and H appear. Thus, the scheme of soft chiral-symmetry breaking remains unchanged. The quark-hadron phase transition in QCD in a magnetic field is studied. It is shown that the phase-transition temperature becomes lower than that in the case of zero magnetic field. 相似文献
18.
Yu. G. Ryabov D. A. Ivanishchev V. G. Ryabov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(11):1507-1512
The production cross sections of ω and ? mesons in p + p, d + Au, and Au + Au collisions at energies √S NN = 63 and 200 GeV have been measured in the PHENIX experiment at RHIC. The results of the measurements in different hadronic and dielectron decay channels are in agreement within the measurement error. The nuclear modification factors R AA measured for both mesons are consistent with the results previously obtained for light neutral mesons. The position and width of the meson mass peaks reconstructed in hadronic decay channels are in agreement with the results of measurements in vacuum. 相似文献
19.
N. M. Agababyan V. V. Ammosov N. Grigoryan H. Gulkanyan A. A. Ivanilov Zh. Karamyan V. A. Korotkov 《Physics of Atomic Nuclei》2011,74(2):239-245
The charged current neutrino production of φ and D s + mesons is studied, using the data obtained with the SKAT bubble chamber exposed to the Serpukhov accelerator neutrino beam. It is found that the φ production occurs predominantly in the forward hemisphere of the hadronic c.m.s. (at x F > 0, x F being the Feynman variable), with the mean yield strongly exceeding the expected yield of directly produced φ mesons and varying from 〈n φ(x F s 0)〉 = (0.92 ± 0.34) × 10?2 at W > 2 GeV up to (1.23 ± 0.53) × 10?2 at W > 2.6 GeV and (1.44 ± 0.69) × 10?2 at W > 2.9 GeV, W being the invariant mass of the hadronic system. For the first time, the inclusive yield of leading D s + mesons carrying more than z = 0.85 of the current c-quark energy is estimated: 〈n D s + (z > 0.85, W > 2.9 GeV)〉 = (6.64 ± 1.91) × 10?2. It is shown that the shape of measured φ meson differential spectrum on xF is reproduced by that expected from the D s + → φX decays. An indication was obtained that this expected spectrum underestimates the measured φ yield. 相似文献
20.
A. K. Murtazaev M. K. Ramazanov D. R. Kurbanova M. K. Badiev Ya. K. Abuev 《Physics of the Solid State》2017,59(6):1103-1109
The replica Monte Carlo method has been used to investigate the critical behavior of a threedimensional antiferromagnetic Ising model on a body-centered cubic lattice, taking into account interactions of the adjacent behind neighbors. Investigations are carried out for the ratios of the values of exchange interactions behind the nearest and next nearest neighbors k = J 2/J 1 in the range of k ∈ [0.0, 1.0] with the step Δk = 0.1. In the framework of the theory of finite-dimensional scaling the static critical indices of heat capacity α, susceptibility γ, of the order parameter β, correlation radius ν, and also the Fisher index η are calculated. It is shown that the universality class of the critical behavior of this model is kept in the interval of k ∈ [0.0, 0.6]. It is established that a nonuniversal critical behavior is observed in the range k ∈ [0.8, 1.0]. 相似文献