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1.
Summary The absolute spectra of atmospheric neutrinos in the vertical direction and at large zenith angle have been estimated directly
from the primary cosmic-ray nucleon spectrum based on the latest JACEE, MSU, SOKOL and CRN data surveyed by Swordy. The Fermi
National Accelerator Laboratory results for pp→K±X, pp→K±X and pp→pX inclusive reactions have been used for theZ-factor calculations for meson production and these were modified for p-air and A-A collisions. The derived muon and electron
neutrino spectra at 0° and 89° from non-prompt meson decay are found comparable with the results of Volkova and Zatsepin,
and Butkevichet al. An estimate of the prompt muon neutrino spectra at 0° and 89° fromtthe charmed-meson decay has been given along with the
earlier results of different authors. The present result for muon neutrino spectra at zenith angles 0° and 89° is found in
approximate agreement with the EAS-TOP results of the Gran Sasso group. 相似文献
2.
《The European Physical Journal C - Particles and Fields》2008,53(1):15-20
The decay J/ψ→ωpp̄ is studied using a 5.8×107 J/ψ event sample accumulated with the BES II detector at the Beijing Electron–Positron Collider. The decay branching fraction
is measured to be B(J/ψ→ωpp̄)=(9.8±0.3±1.4)×10-4. No significant enhancement near the pp̄ mass threshold is observed, and an upper limit of B(J/ψ→ωX(1860))B(X(1860)→pp̄)<1.5×10-5 is determined at the 95% confidence level, where X(1860) designates the near-threshold enhancement seen in the pp̄ mass spectrum
in J/ψ→γpp̄ decays. 相似文献
3.
The integral energy spectrum of primary cosmic rays has been obtained. In the energy range (2.4×103−1.1×105 GeV), the spectrum of all nuclei is consistent with a power law of indexγ=1.55±0.06 and the flux of all nuclei is:N(⩾E
0)⋍(5.1±1.8)×10−1×E
0
−1.55
particles/cm2 sterad. sec., whereE
0 is in GeV. The spectrum of primaryα-particles in the energy range (4.4×103−4.8×104) GeV is also consistent with a power law of indexγ=1.71±0.12 and the flux is:N(⩾E
0)=(4.2±1.4)×10−1×E
0
−1.71
, particles per cm2 sterad. sec, whereE
0 is in GeV. 相似文献
4.
V. I. Medvedev A. A. Vasiliev K. N. Ermakov V. P. Koptev L. M. Kochenda V. I. Poromov O. V. Rogachevsky V. V. Sarantsev V. A. Trofimov S. G. Sherman 《Physics of Atomic Nuclei》2009,72(9):1475-1478
The energy spectrum of a neutron beam produced in a thin-wall liquid-deuterium target by a proton beam of energy 1 GeV was
measured in a hydrogen bubble chamber by detecting events of the reaction np → ppπ
−. 相似文献
5.
A telescope of area 4 m2, consisting of horizontal layers of plastic scintillators, neon flash tubes and absorbers was operated at a depth of 754
hg/cm2 in the Kolar Gold Mines. New values for the vertical intensities of muons have been obtained from observations of the angular
distribution over the slant depths ∼ 750–2300 hg/cm2 and are compared with the existing measurements. From the angular distribution observed, we conclude that muons are produced
wholly through the decay of pions and kaons up to energies of the order of 1 TeV. A value of 0.3±0.2 is estimated for theK/π ratio at production, for muon energies around 500 GeV. A decoherence distribution has been obtained for parallel muon events
up to distances of the order of 10 m. From this we conclude that the averageP
t of the parents of muons of energy ∼ 250 GeV is of the order of 0.3 GeV/c. From an analysis of rock showers, we obtain the
cross section for inelastic interaction of muons of mean energy 100 GeV as (3.8±1.5)×10−30 cm2/nucleon. 相似文献
6.
7.
The energy spectrum of cosmic rays and the fraction of muons with the threshold 1.0secθ GeV in the total number of charged particles in extensive air showers with energy E 0 ≥ 1017 eV according to Yakutsk array data collected during 35 years of its continuous operation in 1978–2012 have been analyzed. It has been shown that these characteristics are noticeably different in different time periods. Before 1996, the integral intensity of the spectrum at E 0 = 1017 eV varied near one stable position and then began to increase. It increased by (45 ± 5)% in seven years and, then, began to decrease. This phenomenon was accompanied a similar change in the fraction of muons and was caused by a significant increase in the average weight of the chemical composition of cosmic rays after 1996 as compared to preceding years. 相似文献
8.
A.G. Akeroyd A. Arhrib Qi-Shu Yan 《The European Physical Journal C - Particles and Fields》2008,55(4):653-665
The charged Higgs boson decays H±→W±A1 and H±→W±Hi are studied in the framework of the next-to-minimal supersymmetric standard model (NMSSM). It is found that the decay rate
for H±→W±A1 can exceed the rates for the τ±ν and tb channels both below and above the top–bottom threshold. The dominance of H±→W±A1 is most readily achieved when A1 has a large doublet component and small mass. We also study the production process pp→H±A1 at the LHC followed by the decay H±→W±A1, which leads to the signature W±A1A1. We suggest that pp→H±A1 is a promising discovery channel for a light charged Higgs boson in the NMSSM with small or moderate tanβ and dominant decay
mode H±→W±A1. This W±A1A1 signature can also arise from the Higgsstrahlung process pp→W±H1 followed by the decay H1→A1A1. It is shown that there exist regions of parameter space where these processes can have comparable cross sections and we
suggest that their respective signals can be distinguished at the LHC by using appropriate reconstruction methods.
PACS 12.60.Fr; 14.80.Cp 相似文献
9.
K. N. Ermakov V. I. Medvedev V. A. Nikonov O. V. Rogachevsky A. V. Sarantsev V. V. Sarantsev S. G. Sherman 《The European Physical Journal A - Hadrons and Nuclei》2011,47(12):159
The detailed investigation of the single pion production reactions pp → pnπ and pp → ppπ at the incident proton momentum 1628 MeV/c has been carried out. The data are analyzed in the framework of the event-by-event maximum-likelihood method together with
the pp → ppπ
0 data measured earlier in the energy region below 1 GeV. At 1628 MeV/c the largest contributions stem from the 3
P
2, 3
P
1, 3
P
0, 1
D
2 and 3
F
2 initial partial waves. 相似文献
10.
O. G. Ryazhskaya 《Il Nuovo Cimento C》1995,18(1):77-80
Summary The background produced by isolated neutrons in Cherenkov detectors studying the atmospheric neutrinos is discussed. The neutrons
are generated in nuclear showers initiated by muons in the rock surrounding the detectors. It is shown that, taking into account
the detection of π0 events from reactions of nA→π0X, which look likev
e detection, results in an observedI(v
μ)/I(v
e) ratio close to the expected one for the energy range 0.2–5 GeV. 相似文献
11.
We show how a measurement of the process pp→tt̄H0+X at the Large Hadron Collider (LHC) and a measurement of the Higgs boson branching ratios BR(H0→bb̄) and BR(H0→W+W-) at a future linear electron positron collider (ILC) can be combined to extract a value of the top quark Yukawa coupling
in a model-independent way. We find that for masses with 120 GeV/c2<mH<200 GeV/c2 a measurement precision of 15% including systematic uncertainties can be achieved for integrated luminosities of 300 fb-1 at the LHC and 500 fb-1 at the ILC at a centre-of-mass energy of 350 GeV. 相似文献
12.
Xiao-Gang He Xue-Qian Li Xiang Liu Jian-Ping Ma 《The European Physical Journal C - Particles and Fields》2007,49(3):731-736
Recently the BES collaboration has announced the observation of a resonant state in the π+π-η’ spectrum in J/ψ→γπ+π-η’ decay. Fitting the data with a 0-+ state, the mass is determined to be 1833.7 MeV with 7.7σ statistic significance. This state is consistent with the one extracted
from previously reported pp̄ threshold enhancement data in J/ψ→γpp̄. We study the properties of this state using QCD anomaly
and QCD sum rules, assuming X(1835) to be a pseudoscalar, and we show that it is consistent with the data. We find that this
state has a sizeable matrix element , leading to branching ratios of (2.61–7.37)×10-3 and (2.21–10.61)×10-2 for J/ψ→γGp and for Gp→π+π-η′, respectively. Combining the calculated branching ratio of J/ψ→γGp and data on threshold enhancement in J/ψ→γpp̄, we determine the coupling for the Gp–p–p̄ interaction. We finally study the branching ratios of the other J/ψ→γ+three mesons decay modes. We find that J/ψ→γGp→γ(π+π-η,KKπ0) can provide useful tests for the mechanism proposed.
PACS 11.55.Hx; 12.39.Fe; 12.39.Mk; 13.25.Gv 相似文献
13.
S.V. Golovkin A.P. Kozhevnikov V.P. Kubarovsky V.F. Kurshetsov L.G. Landsberg V.V. Molchanov V.A. Mukhin S.V. Petrenko V.A. Senko D.V. Vavilov V.A. Victorov V.Z. Kolganov G.S. Lomkatsi A.F. Nilov V.T. Smolyankin 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):409-416
New data for the diffractive reaction p+N→ [Σ0
K
+] +N at E
p= 70 GeV were obtained with partially upgraded SPHINX setup. The data are in a good agreement with the results of our previous
study of this reaction. In the mass spectrum M(Σ0
K
+) a structure at the threshold region with a mass ∼1810 MeV and a distinct X(2000) peak with M= 1989 ± 6 MeV and γ= 91 ± 20 MeV are observed. Unusual features of the massive X(2000) state (narrow decay width, anomalously
large branching ratio for the decay channel with strange particle emission) make it a serious candidate for cryptoexotic pentaquark
baryon with hidden strangeness |qqqsˉs>. We also present new results on the narrow threshold structure X(1810) with M= 1807 ± 7 MeV and γ= 62 ± 19 MeV which is produced in the region of very small P
2
T < 0.01 GeV2. The possibility of the Coulomb production mechanism for X(1810) is discussed.
Received: 28 April 1999 相似文献
14.
Summary Energy spectra and zenith-angle distributions of cosmic-ray muons, neutrinos and antineutrinos of prompt generation for energy
interval (1÷106) TeV are calculated. For calculations of differential cross-sections of D±, D0,
0 and Λc production inNN and πN interactions the recombination quark-parton model (RQPM) is used. Accounting of nuclear effects is done by using the additive
quark model and the optical model of nucleus. Detailed comparison of results obtained in RQPM with corresponding predictions
of quark-gluon string model (MQGS) is carried out. Dynamics of semi-leptonic D- and Λc and energy losses of muons in the atmosphere are taken into account. Calculations of hadronic cascades in the atmosphere
are done with accounting of growth with energy of total inelastic hadron-nucleus cross-sections, steepening of primary cosmic-ray
spectrum and processes of pion regeneration. The comparison of our calculations with experimental data and with calculations
of other authors is given. 相似文献
15.
M. Sioli 《Physics of Atomic Nuclei》2006,69(11):1842-1846
The energy spectrum of neutrino-induced upward-going muons in MACRO has been analyzed in terms of effects of violating relativity
principles, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of ν
μ → ν
τ transitions. The data disfavor these exotic possibilities even at a subdominant level, and stringent 90% C.L. limits are
placed on the Lorentz invariance violation parameter |Δυ| < 6 × 10−24 at sin(2ϑυ) = 0 and |Δυ| < (2.5–5) × 10−26 at sin(2ϑυ) = ±1. These limits can also be reinterpreted as upper bounds on the parameters describing violation of the equivalence principle.
The text was submitted by the author in English. 相似文献
16.
Summary The vertical differential and integral, muon spectra at super-high energies,viz. up to 10 TeV have been estimated from our predicted primary spectrum of the formN(E)dE=2.4E
−2.7dE (cm2s sr GeV)−1. The accelerator data of Johnsonet al., Elbertet al. have been used for the evaluation of fractional hadronic energy moments. By using the conventional Feynman scaling hypothesis
and the meson atmospheric diffusion equation after Bugaevet al., the differential and integral muon spectra have been estimated and the results are well in accord with the experimental
data of Bakeret al., Allkoferet al., Ayreet al., Aminevaet al., Menon and Ramana Murthy, and Sheldonet al. in the spectral range (0.1÷10) TeV. 相似文献
17.
S. N. Popov 《Physics of the Solid State》1999,41(7):1175-1181
The temperature dependences of NQR line frequencies and widths of 121Sb (for the ±1/2→±3/2 transition) and of 123Sb (for the ±1/2→±3/2 and ±3/2→±5/2 transitions), as well as of the principal components and the asymmetry parameter of the
electric-field-gradient tensor at the 123Sb nucleus have been studied in a SbSI crystal in the 115–325 K range. The dynamic and static factors governing the character
of these relations are discussed. The ±1/2→±3/2 line in the 121Sb NQR spectrum splits into a doublet within a narrow (0.5 K) temperature interval near the ferroelectric phase transition
(T
c=293 K), which is associated with the formation of a macroscopic heterophase structure in the crystal.
Fiz. Tverd. Tela (St. Petersburg) 41, 1286–1292 (July 1999) 相似文献
18.
W. Bartel D. Cords P. Dittmann R. Eichler R. Felst D. Haidt S. Kawabata H. Krehbiel B. Naroska L.H. ONeill J. Olsson P. Steffen W.L. Yen E. Elsen M. Helm A. Petersen P. Warming G. Weber C. Yanagisawa 《Physics letters. [Part B]》1981,99(3):277-280
We have observed the production of prompt muons in e+e? annihilation in the centre of mass energy range 33.0 GeV to 35.8 GeV. The rate of such muons with momentum greater than 1.4 GeV was measured to be 0.069 ± 0.024 per multiparticle event. When compared with currently accepted models, this rate is consistent with that expected from charm and bottom decays, but does not support the production also of a top quark of mass less than about 15 GeV. 相似文献
19.
An investigation on the interaction of high energy muons, associated with EAS and having energies greater than several hundred GeV, has been carried out at Kolar Gold Fields. A visual detector consisting of neon flash tube hodoscope has been used together with a scintillator detector to observe the muons and accompanying showers at the underground level. It has been found that nearly 90% of the showers observed at the underground level are generated in course of pure electromagnetic interactions of the muons with the matter traversed by them. The observed number of the showers is found to be consistent with the expected number calculated using the cross-sections for knock-on, bremsstrahlung and direct pair production processes. Rest of the observed showers do not appear to fit in the pure electromagnetic interaction scheme. Various possible production processes for these events have been discussed. Considering these events to be due to photonuclear interaction of muons in the rock, the observed number leads to a production cross-sectionσ μ (?25 GeV) ?(1.6±0.75)10?29 cm2/nucl. 相似文献
20.
The extensive thermal emission spectrum attributed to the diatomic bromides of calcium, strontium and barium has been observed
in the visible region at temperatures about 2200–2400° C, using a vacuum graphite furnace. Many new bands,viz., 141 in CaBr, 53 in SrBr and 68 in BaBr, have been recorded and classified. The vibrational constants agree with those determined
by earlier workers and involved the ground state in each case. The transition C→X apears in each molecule and consists of
two equally intense systems,viz., C1→X and C2→X. The general spectroscopic features of the C→X systems of the bromides of the II A sub group of the periodic table have
been compared. They exhibit a close structural similarity and furnish a good example of homologous spectra. The system C→X
in all these molecules arises from a C2
π−X2
Σ
+ transition where the2
π state appears to be intermediate between Hund’s cases (a) and (b). 相似文献