共查询到20条相似文献,搜索用时 15 毫秒
1.
A.A. Bagneid 《The European Physical Journal C - Particles and Fields》2008,54(4):547-553
We examine distributions of leptons produced in e+e- collisions, by a family nonuniversal extra gauge boson Z′, suggested by the model, and by other neutral gauge bosons occurring in left–right symmetric models and in superstring-inspired E6 models. We discuss how to distinguish the models by examining the couplings to fermions of the extra Z-boson through its
leptonic production cross sections and asymmetries. We show how the universality violation inherent in the model enhances the discovery potential of Z′ at future planned and proposed e+e- colliders. 相似文献
2.
Xuelei Wang Yaobei Liu Jihong Chen Hua Yang 《The European Physical Journal C - Particles and Fields》2007,49(2):593-597
The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs
model, we study the process e+e-→e+e-H at the ILC and calculate the correction of the littlest Higgs model to the cross section of this process. The results show
that, in the favorable parameter spaces preferred by the electroweak precision data, the value of the relative correction
is in the range from a few percent to tens percent. In most cases, the correction is large enough to reach the measurement
precision of the ILC. Therefore, the correction of the littlest Higgs model to the process e+e-→e+e-H might be detected at the ILC, which will give an ideal way to test the model.
PACS 12.60.Nz; 14.80.Mz; 12.15.Lk; 14.65.Ha 相似文献
3.
N. Yongram 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):71-74
Spin correlations are carefully investigated in elastic e+e- scattering in QED, for initially polarized as well as unpolarized particles,
with emphasis placed on energy or speed of the underlying particles involved in the process. An explicit expression is derived
for the corresponding transition probabilities in closed form to the leading order. These expressions differ from those
obtained from simply combining the spins of the relevant particles, which are of kinematic nature.
It is remarkable that these explicit results obtained from quantum field theory show a clear violation of Bell's inequality
at all energies, in support of
quantum theory in the relativistic regime. We hope that our explicit expression will lead to experiments, of the type described
in the bulk of this paper, that monitor speed. 相似文献
4.
A.E. Dorokhov E.A. Kuraev Yu.M. Bystritskiy M. Sečanský 《The European Physical Journal C - Particles and Fields》2008,55(2):193-198
We reconsider QED radiative corrections (RC) to the π0→e+e- decay width. One kind of RC investigated earlier has a renormalization group origin and can be associated with the final
state interaction of electron and positron. It determines the distribution of lepton pair invariant masses in the whole kinematic
region. The other type of RC has a double-logarithmic character and is related to almost on-mass-shell behavior of the lepton
form factors. The total effect of RC for π0→e+e- decay is estimated to be 3.2%, and for η→e+e- decay it is 4.3%.
PACS 13.25.Cq; 12.38.Lg; 12.38.-t 相似文献
5.
We consider semi-inclusive unpolarized DIS for the production of charged kaons and the different possibilities to test the
conventionally used assumptions s-s̄=0 and Dd
K+-K-=0. The tests considered have the advantage that they do not require any knowledge of the fragmentation functions. We also
show that measurements of both charged and neutral kaons would allow for the determination of the kaon fragmentation functions
Dq
K++K- solely from SIDIS measurements, and we discuss the comparison of (Du-Dd)K+-K- obtained independently in SIDIS and e+e- reactions. All analyses are performed in LO and NLO in QCD. The feasibility of the tests to HERMES SIDIS data is considered.
PACS 12.38.Bx; 13.85.Ni 相似文献
6.
The multiple hadron production in the events induced by the heavy primary quarks in e+e- annihilation is reconsidered with account of corrected experimental data. A new value for the multiplicity in bb̄ events
is presented on the basis of pQCD estimates. 相似文献
7.
A. Gay 《The European Physical Journal C - Particles and Fields》2007,49(2):489-497
Understanding the mechanism of electroweak symmetry breaking and the origin of boson and fermion masses is among the most
pressing questions raised in contemporary particle physics. If these issues involve one (several) Higgs boson(s), a precise
measurement of all its (their) properties will be of prime importance. Among those, the Higgs coupling to matter fermions
(the Yukawa coupling). At a linear collider, the process e+e-→tt̄H will allow a direct measurement of the top-Higgs Yukawa coupling. We present a realistic feasibility study of the measurement
in the context of the TESLA collider. Four channels are studied and the analysis is repeated for several Higgs mass values
within the range 120–200 GeV/c
2.
PACS 13.66.Jn; 14.65.Ha; 14.80.Bn 相似文献
8.
We present the combined results on electron-pair production in 158 GeV/n Pb-Au (
= 17.2 GeV) collisions taken at the CERN SPS in 1995 and 1996, and give a detailed account of the data analysis. The enhancement over the reference of neutral meson decays amounts to a factor of 2.31
for semi-central collisions (28
) when yields are integrated over m > 200 MeV/c2 in invariant mass. The measured yield, its stronger-than-linear scaling with
, and the dominance of low pair pt strongly suggest an interpretation as thermal radiation from pion annihilation in the hadronic fireball. The shape of the excess centring at
500 MeV/c2, however, cannot be described without strong medium modifications of the
meson. The results are put into perspective by comparison to predictions from Brown-Rho scaling governed by chiral symmetry restoration, and from the spectral-function many-body treatment in which the approach to the phase boundary is less explicit.Received: 2 March 2005, Published online: 8 June 2005 相似文献
9.
Chong-Xing Yue Nan Zhang Shi-Hai Zhu 《The European Physical Journal C - Particles and Fields》2008,53(2):215-219
The littlest Higgs model with T-parity predicts the existence of the T-odd particles, which can only be produced in pairs.
We consider pair production of the T-odd leptons in a future high energy linear e+e- collider (ILC). Our numerical results show that, as long as the T-odd leptons are not too heavy, they can be copiously produced
and their possible signals might be detected via the processes e+e-→L̄iLj in future ILC experiments. 相似文献
10.
We present an estimate of the cross-section for the exclusive production of a ρL
0-meson pair in e+e- scattering, which will be studied in the future high-energy International Linear Collider. For this aim, we complete calculations
of the Born order approximation of the amplitudes γ*
L,T(Q1
2)γ*
L,T(Q2
2)→ρL
0ρL
0, for arbitrary polarization of virtual photons and longitudinally polarized mesons, in the kinematical region s≫-t,Q1
2,Q2
2. These processes are completely calculable in the hard region Q1
2,Q2
2≫Λ2
QCD, and we perform most of the calculations in an analytical way. The resulting cross-section turns out to be large enough for
this process to be measurable with foreseen luminosity and energy, for Q1
2 and Q2
2 in the range of a few GeV2. 相似文献
11.
R.M. Godbole S.K. Rai S. Raychaudhuri 《The European Physical Journal C - Particles and Fields》2007,50(4):979-990
The electromagnetic radiation emitted by colliding beams is expected to play an important role at the next generation of high
energy e+e- linear colliders. Focussing on the simplest process, e+e-→μ+μ-, we show that, for suitable machine parameters and luminosity, radiative effects like initial state radiation (ISR) and beamstrahlung
can be used to search for resonant graviton modes of the Randall–Sundrum model in an efficient manner. 相似文献
12.
Chong-Xing Yue Shuang Zhao 《The European Physical Journal C - Particles and Fields》2007,50(4):897-903
The littlest Higgs (LH) model predicts the existence of the doubly charged scalars , which generally have large flavor changing couplings to leptons. We calculate the contributions of Φ±± to the lepton flavor violating (LFV) processes li→ljγ and li→ljlklk, and we compare our numerical results with the current experimental upper limits on these processes. We find that some of
these processes can give severe constraints on the coupling constant Yij and the mass parameter MΦ. Taking into account the constraints on these free parameters, we further discuss the possible lepton flavor violating signals
of at high energy linear e+e- collider (ILC) experiments. Our numerical results show that the possible signals of might be detected via the subprocesses e±e±→l±l± in future ILC experiments. 相似文献
13.
The W + W- production cross section is measured from a data sample corresponding to a total integrated luminosity of 683 pb-1, collected by the ALEPH experiment at LEP at centre-of-mass energies from 183 to 209 GeV. Individual cross sections for the different topologies arising from W decays into leptons or hadrons, as well as the total W-pair cross section are given at eight centre-of-mass energies. The results are found to be in agreement with recently developed Standard Model calculations at the one percent level. The hadronic branching fraction of the W boson is measured to be
= 67.13
0.37(stat.)
0.15(syst.)%, from which the CKM matrix element
is determined to be 0.958
0.017(stat.)
0.008(syst.)Received: 1 October 2004, Published online: 15 November 2004 相似文献
14.
A. Basu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(1):51-55
Electron-hydrogen scattering has been investigated in
Debye plasma environment employing the close-coupling approximation. Two
models, viz., 6-state CCA and 9-state CCA have been used. Plasma screening
has been taken into account via Debye-Hückel model potential. The
lowest lying 1De^1{\rm D}^{{\rm e}} auto-detaching resonance of the hydrogen negative
ion has been successfully predicted for various plasma conditions. The
resonant state changes to shape resonance for Debye scattering lengths less
than a critical value. 相似文献
15.
DELPHI data collected at centre-of-mass energies up to 208 GeV have been analysed to search for charginos, neutralinos and sfermions in the framework of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation. No evidence for a signal was found in any of the channels. The results of each search were used to derive limits on production cross-sections and particle masses. In addition, the combined result of all searches excludes regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles.Received: 22 February 2003, Revised: 24 July 2003, Published online: 12 November 2003 相似文献
16.
N. Oshimo 《The European Physical Journal C - Particles and Fields》2005,39(3):383-388
The measurability of generation mixing is studied on pair production of sneutrinos in e
+
e
- collisions and their subsequent decays into two different charged leptons e and μ with two lighter charginos. The analyses are made systematically in a general framework of the supersymmetric extension
of the standard model. The production and decay process depends on the parameters of the chargino sector as well as those
of the sneutrino sector. Although generation-changing interactions are severely constrained by radiative charged-lepton decays,
sizable regions in the parameter space could still be explored at e
+
e
- colliders in the near future.
Received: 6 October 2004, Revised: 14 November 2004, Published online: 14 January 2005
PACS:
11.30.Hv, 12.15.Ff, 12.60.Jv, 14.80.Ly 相似文献
17.
The influence of phosphate glass electrode in the configuration of resistive plate chamber has been studied using GEANT3.21
Monte Carlo code. Bakelite electrodes were replaced by phosphate glass electrodes, as these glass materials have low bulk
resistivity, are portable and easy to handle. These types of RPCs in their compact form of all materials are suitable for
high rate background environment. We find that these new types of RPCs give little higher response to γ-rays and e+/e− particles, both for single-and double gap RPCs. The results of simulation are discussed.
相似文献
18.
Complementing the preceding study of charged scalar leptons, the sector of the neutral scalar leptons, sneutrinos, is investigated in a high-precision analysis for future e
+
e
- linear colliders. The theoretical predictions for the cross-sections are calculated at the thresholds for non-zero widths and in the continuum including higher-order corrections at the one-loop level. Methods for measuring the sneutrino masses and the electron-sneutrino-gaugino Yukawa couplings are presented, addressing theoretical problems specific for the sneutrino channels.Received: 10 September 2004, Revised: 11 October 2004, Published online: 3 March 2005 相似文献
19.
Doubly-charged scalars, predicted in many models having exotic Higgs rep-resentations, can in general have lepton-number violating
(LFV) couplings. We show that by using an associated monoenergetic final state photon seen at a future linear e
−
e
− collider, we can have a clear and distinct signature for a doubly-charged resonance. The strength of the ΔL = 2 coupling can also be probed quite effectively as a function of the recoil mass of the doubly-charged scalar.
相似文献
20.
The potential of a linear e + e- collider operated at a centre-of-mass energy of 350 GeV is studied for the measurement of the Higgs boson mass. An integrated
luminosity of 500 fb-1 is assumed. For Higgs boson masses of 120, 150 and 180 GeV the uncertainty on the Higgs boson mass measurement is estimated
to be 40, 65 and 70 MeV, respectively. The effects of beam related systematics, namely a bias in the beam energy measurement,
the beam energy spread and the luminosity spectrum due to beamstrahlung, on the precision of the Higgs boson mass measurement
are investigated. In order to keep the systematic uncertainty on the Higgs boson mass well below the level of the statistical
error, the beam energy measurement must be controlled with a relative precision better than 10-4.
Received: 30 May 2005, Revised: 6 July 2005, Published online: 6 October 2005 相似文献