共查询到20条相似文献,搜索用时 31 毫秒
1.
V. I. Telnov 《Pramana》2007,69(6):957-961
At linear colliders, the e
+
e
− luminosity is limited by beam-collision effects, which determine the required emittances of beams in damping rings (DRs).
In γγ collisions at the photon collider, these effects are absent, and so smaller emittances are desirable. In the present damping
ring designs, nominal DR parameters correspond to those required for e
+
e
− collisions. In this note, I would like to stress once again that as soon as we plan the photon collider mode of ILC operation,
the damping ring emittances are dictated by the photon collider requirements — namely, they should be as small as possible.
This can be achieved by adding more wigglers to the DRs; the incremental cost is easily justified by a considerable potential
improvement of the γγ luminosity. No expert analysis exists as of now, but it seems realistic to obtain a factor five increase of the γγ luminosity compared to the ‘nominal’ DR design.
相似文献
2.
Klaus Mönig 《Pramana》2007,69(6):1181-1184
The photon collider is an option at the ILC. In this note detector issues are discussed that are relevant for the change from
the e
+
e
− mode of the ILC to the γγ mode.
相似文献
3.
We examine the sensitivity of eγ colliders (based on e
+
e
− linear colliders of c.m. energy 500 GeV) to the anomalous couplings of the Higgs to W-boson via the process e
−
γ → νWH. This has the advantage over e
+
e
− collider in being able to dissociate WWH vertex from ZZH. We are able to construct several dynamical variables which may be used to constrain the various couplings in the WWH vertex.
相似文献
4.
We have performed a detailed study of the power losses in the post-collision extraction line of a TeV e
+
e
− collider with a crossing angle of 20 mrad at the interaction point. Five cases were considered: four luminosity configurations
for ILC and one for CLIC. For all of them, the strong beam-beam effects at the interaction point lead to an emittance growth
for the outgoing beam, as well as to the production of beamstrahlung photons and e
+
e
− coherent pairs. The power losses along the extraction line, which are due to energy deposition by a fraction of the disrupted
beam, of the beamstrahlung photons and of the coherent pairs, were estimated in the case of ideal collisions, as well as with
a vertical position or angular offset at the interaction point.
相似文献
5.
Fawzi Boudjema 《Pramana》1998,51(1-2):249-271
The physics at the plannede
+
e
- colliders is discussed around three main topics corresponding to different manifestations of symmetry breaking:W physics in the no Higgs scenario, studies of the properties of the Higgs and precision tests of SUSY. A comparison with the
LHC is made for all these cases. The γγ mode of the linear collider will also be reviewed. 相似文献
6.
Gautam Bhattacharyya 《Pramana》2007,69(5):903-907
We consider the UED scenario and study the detectability of the first KK electron-positron pair at the ILC. A few hundred
GeV KK electron decays into a nearly degenerate KK photon, which carries away missing energy, and the standard electron. The
mass splitting between the KK electron and KK photon is controlled by the bulk-and brane-induced radiative corrections. We
look for the signal event e
+
e
− + large missing energy for √s = 1 TeV and observe that with a few hundred fb−1 luminosity the signal can be deciphered from the standard model background. We briefly outline how the UED signals may be
distinguished from the supersymmetric signals.
This talk is based on a work the author did with Paramita Dey, Anirban Kundu and Amitava Raychaudhuri [1]. 相似文献
7.
Sunanda Banerjee 《Pramana》2000,55(1-2):85-100
Several studies have been made to the hadronic final states in e
+
e
− collisions at LEP. Studies of the annihilation process at LEP2 have given rise to results on jet rate, event shape, heavy
flavour production, inclusive momentum spectra, Bose-Einstein correlation and colour reconnection effects. Event shape studies
have given rise to accurate determination of the strong coupling constant α
s using O (α
s
2
) with resummed leading and next-to-leading log calculation and also with power law corrections. Studies of 2-photon processes
have yielded results on γγ cross-section, heavy flavour production, photon structure function and γ*γ* scattering. 相似文献
8.
Saurabh D Rindani 《Pramana》2006,67(4):579-596
The talk described the prospects of studying standard model parameters as well as scenarios beyond the standard model, like
the minimal supersymmetric standard model, theories with extra dimensions and theories with extra neutral gauge bosons, at
a future linear e
+
e
− collider. 相似文献
9.
Probir Roy 《Pramana》2007,69(5):895-901
An event-shape analysis of the dileptons in the process e
+
e
− → ℓ+ℓ−
, studied in ILC or CLIC, can clearly discriminate between a supersymmetric or a large extra dimensional (ADD) production
mechanism.
相似文献
10.
We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct
polarization asymmetries which can isolate the contribution of a Higgs boson ϕ in γγ → f
, f = τ/t, from that of the QED continuum. This can help in getting information on the γγϕ coupling in case ϕ is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case ϕ has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these
asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well
as its CP properties over a wide range of MSSM parameters.
相似文献
11.
D. Habs B. M. Hegelich J. Schreiber P. G. Thirolf 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(2):253-264
The use is suggested of a laser-accelerated dense electron sheet with
an energy of (E=[(g)\tilde] mc2E=\tilde{\gamma} mc^2) as a relativistic mirror to reflect coherently a second
laser with photon energy ħω, generating by the Doppler boost
high-energy γ photons with $
\hbar \omega ' = 4\tilde \gamma ^2 \hbar \omega
$
\hbar \omega ' = 4\tilde \gamma ^2 \hbar \omega
and
short duration [A. Einstein, Annalen der Physik 17, 891 (1905); D. Habs et al., Appl. Phys. B 93, 349 (2008)]. Two of these counter-propagating
γ beams are focused by the parabolically shaped electron sheets into the
interaction region with small, close to diffraction-limited, spot size.
Comparing the new nγ-mγ collider with former proposed
γγ collider schemes we achieve the conversion of many
photon-pairs in a small space-time volume to matter-antimatter particles,
while in the other discussed setups only two isolated, much more
high-energetic photons will be converted, reaching in the
new approach much higher energy densities and temperatures.
With a γ-field strength somewhat below the Schwinger limit we can
reach this complete conversion of the γ bunch energy into
e+e- or quark-antiquark q[`(q)]q\bar{q}-plasmas.
For a Bose-Einstein condensate (BEC) [A. Einstein, Physikalisch-mathematische Klasse (Berlin) 22, 261 (1924); A. Einstein, Physikalisch-mathematische Klasse (Berlin) 22, 3 (1925); A. Griffin, D.W. Snoke, S. Stringari, Bose-Einstein Condensation (Cambridge University Press, 1995)] final state or for the Cooper pair ground state at higher densities [A.J. Leggett, Quantum Liquids, Oxford Graduate Texts (Oxford University Press, 2006)] the strong induced transition
into this coherent state is of special interest for single-cycle γ
pulses. Due to annihilation these cold coherent states are very
short-lived. For γ beams with photon energies
of 1–10 keV the rather cold e+e--plasma or
e+e--BEC expands to a cold dense aggregate of positronium (Ps)
atoms, where the production of Ps molecules is discussed.
For photon energies of 1–10 MeV we discuss the production of
a cold induced π0-BEC followed by the formation of molecules.
For the direct population of higher q[`(q)]q\bar{q} densities we can study
condensates of color-neutral mesons with enhanced population.
For a γγ collider with several-cycle laser pulses
the following cycles heat up the fermion-antifermion
f[`(f)]f\bar{f} system to a certain temperature.
Thus we can reach high energy densities and temperatures of an e+e-γ
plasma, where the production of hadrons in general or the quark-gluon
phase transition can be observed. Within the long-term goal of very
high photon energies of about 1 GeV in the nγ-mγ-collider,
even the electro-weak phase transition or SUSY phase transition
could be reached. 相似文献
12.
Saurabh D. Rindani 《Pramana》2007,69(5):883-887
With the use of transverse polarization (TP), a CP-odd and T-odd observable can be constructed when the final-state particles
are self-conjugate. In the case of HZ production, this observable can be used to probe a certain effective four-point e
+
e
−
ZH CP-violating coupling, not accessible without TP. Effective CP-violating ZZH coupling does not contribute to this observable. A similar observable in γZ production can be used to probe e
+
e
−
γZ four-point couplings.
相似文献
13.
S. Heinemeyer 《Pramana》2007,69(5):727-733
The international linear e
+
e
− collider (ILC) could go into operation in the second half of the upcoming decade. Experimental analyses and theory calculations
for the physics at the ILC are currently performed. We review recent progress, as presented at the LCWS06 in Bangalore, India,
in the fields of Higgs boson physics and top/QCD. Also the area of loop calculations, necessary to achieve the required theory
precision, is included.
相似文献
14.
J. Kovermann A. Stahl A. A. Mikhailichenko D. Scott G. A. Moortgat-Pick V. Gharibyan P. Pahl R. Pöschl K. P. Schüler K. Laihem S. Riemann A. Schälicke R. Dollan H. Kolanoski T. Lohse T. Schweizer K. T. McDonald Y. Batygin V. Bharadwaj G. Bower F. -J. Decker C. Hast R. Iverson J. C. Sheppard Z. Szalata D. Walz A. Weidemann G. Alexander E. Reinherz-Aronis S. Berridge W. Bugg Y. Efrimenko 《Pramana》2007,69(6):1165-1169
A longitudinal polarized positron beam is foreseen for the international linear collider (ILC). A proof-of-principle experiment
has been performed in the final focus test beam at SLAC to demonstrate the production of polarized positrons for implementation
at the ILC. The E166 experiment uses a 1 m long helical undulator in a 46.6 GeV electron beam to produce a few MeV photons
with a high degree of circular polarization. These photons are then converted in a thin target to generate longitudinally
polarized e
+ and e
−. The positron polarization is measured using a Compton transmission polarimeter. The data analysis has shown asymmetries
in the expected vicinity of 3.4% and ∼1% for photons and positrons respectively and the expected positron longitudinal polarization
is covering a range from 50% to 90%.
相似文献
15.
Measurement of the heavy neutral MSSM Higgs bosons H and A production in the process γγ → A/H → b
at the Photon Linear Collider [1,2] has been considered in two independent analyses for the parameter range corresponding
to the so-called ‘LHC wedge’. Significantly different conclusions were obtained; signal-to-background ratio 36 vs. 2. Here
assumptions and results of these two analyses are compared. We have found that differences in the final results are mainly
due to different assumptions on γγ-luminosity spectra, jet definitions and selection cuts.
相似文献
16.
The minimal supersymmetric extension of the standard model (MSSM) predicts the existence of new charged and neutral Higgs
bosons. The pair creation of these new particles at the multi-TeV e
+
e
− compact linear collider (CLIC), followed by decays into standard model particles, were simulated along with the corresponding
background. High-energy beam-beam effects such as ISR, beamstrahlung and hadronic background were included. We have investigated
the possibility of using the ratio between the number of events found in various decay channels to determine the MSSM parameter
tan β and we have derived the corresponding statistical error from the uncertainties on the measured cross-sections and Higgs boson
masses.
相似文献
17.
The minimal supersymmetric extension of the standard model (MSSM) predicts the existence of new charged and neutral Higgs
bosons. The pair creation of these new particles at the multi-TeV e
+
e
− compact linear collider (CLIC), followed by decays into standard model particles, were simulated along with the corresponding
background. High-energy beam-beam effects such as ISR, beamstrahlung and hadronic background were included. We have investigated
the possibility of using the ratio between the number of events found in various decay channels to determine the MSSM parameter
tan β and we have derived the corresponding statistical error from the uncertainties on the measured cross-sections and Higgs boson
masses.
相似文献
18.
Rohini M. Godbole Agnes Grau Rohit Hegde Giulia Pancheri Yogi Srivastava 《Pramana》2006,66(4):657-668
In this note, we summarize and compare various model predictions forpp total cross-section σ
tot
pp
, giving an estimate of the range of predictions for the total cross-section, σ
tot
pp
expected at the LHC. We concentrate on the results for σ
tot
pp
obtained in a particular QCD based model of the energy dependence of the total cross-section, including the effect of soft
gluon radiation. We obtain the range of predictions in this model by exploring the allowed range of model parameters. We further
give a handy parametrisation of these results which incidentally spans the range of various other available predictions at
the LHC as well 相似文献
19.
George W S Hou 《Pramana》2006,67(5):773-782
There are currently two hints for new physics involving CP violation in b → s transitions: ΔS ≡ S
f − S
J
ϕK
≠ 0, and difference in direct CP asymmetry ΔA
Kπ
≡ A
K+π
0
− A
K+π
−
≠ 0. We explore the two scenarios with a large and unique new CP phase in b ↔ s transitions. Motivated by ΔS ≠ 0, we update on the right-handed strange-beauty squark sb
1R at TeV scale. Motivated by ΔA
Kπ
≠ 0, we explore sequential fourth generation t′ and b′ quarks. Both scenarios can survive constraints such as SM level b → sγ, sll and B
s mixing, and predict sizable CP violation in B
s mixing. The fourth generation picture predicts sizable K
L → π
0
vv. Direct search for sb
R, b′ and t′ at hadronic colliders, such as Tevatron Run II and LHC, can complement further CP violation studies at these machines, as
well as at the future Super B factory. 相似文献
20.
Identified π±,K
±, p and -p transverse momentum spectra at mid-rapidity in √sNN = 130 GeV Au-Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average
transverse momenta increase with the number of participating nucleonsN
part similarly for all particle species. The multiplicity densities scale faster thanN
part. TheK
± andp
±yields per participant increase faster than the π± yields. We combine the PHENIX neutral and charged pion measurement and find that in central collisions forp
T >-2 GeV/c,-p andp yields are comparable to or even exceed the pion yields. 相似文献