The role of beamstrahlung in high-energy e(+)e(-) storage-ring colliders (SRCs) is examined. Particle loss due to the emission of single energetic beamstrahlung photons is shown to impose a ...fundamental limit on SRC luminosities at energies 2E(0)≳140 GeV for head-on collisions and 2E(0)≳40 GeV for crab-waist collisions. With beamstrahlung taken into account, we explore the viability of SRCs in the 2E(0)=240-500 GeV range, which is of interest in the precision study of the Higgs boson. At 2E(0)=240 GeV, SRCs are found to be competitive with linear colliders; however, at 2E(0)=400-500 GeV, the attainable SRC luminosity would be a factor 15-25 smaller than desired.
Recently, a
γ
γ
collider based on the existing 17.5 GeV linac of the European XFEL has been proposed. High-energy photons will be generated by Compton scattering of laser photons with a wavelength of ...0.5–1
μ
m
on electrons. Such a photon collider covers the range of invariant masses
W
γ
γ
<
12
Ge
V
/
c
2
. The physics program includes spectroscopy of
C
-even resonances (
c
-,
b
-quarkonia, 4-quark states, glueballs) in various
J
P
states. Variable circular and linear polarizations will help in determining the quantum numbers. In this paper, we present a summary of measured and predicted two-photon widths of various resonances in the mass region 3–12
Ge
V
/
c
2
and investigate the experimental possibility of observing these heavy two-photon resonances under the conditions of a large multi-hadron background. Registration of all final particles is assumed. The minimum values of
Γ
γ
γ
(
W
)
are obtained at which resonances can be detected at a
5
σ
confidence level in 1 year of operation.
Abstract
Recently, a
$$\gamma \gamma $$
γ
γ
collider based on the existing 17.5 GeV linac of the European XFEL has been proposed. High-energy photons will be generated by Compton scattering of laser ...photons with a wavelength of 0.5–1
$${\,\upmu \mathrm m}$$
μ
m
on electrons. Such a photon collider covers the range of invariant masses
$$W_{\gamma \gamma } <12$$
W
γ
γ
<
12
$${\mathrm {\,Ge V\!/}c^2}$$
Ge
V
/
c
2
. The physics program includes spectroscopy of
$$ C $$
C
-even resonances (
c
-,
b
-quarkonia, 4-quark states, glueballs) in various
$$J^P$$
J
P
states. Variable circular and linear polarizations will help in determining the quantum numbers. In this paper, we present a summary of measured and predicted two-photon widths of various resonances in the mass region 3–12
$${\mathrm {\,Ge V\!/}c^2}$$
Ge
V
/
c
2
and investigate the experimental possibility of observing these heavy two-photon resonances under the conditions of a large multi-hadron background. Registration of all final particles is assumed. The minimum values of
$$\varGamma _{\gamma \gamma }(W)$$
Γ
γ
γ
(
W
)
are obtained at which resonances can be detected at a
$$5\sigma $$
5
σ
confidence level in 1 year of operation.
Photon colliders (γγ, γe) have been considered a natural addition to e+e− linear-collider projects for more than 30 years 1, 2. It was a common opinion that such linear collider with four types of ...colliding beams (plus e+e−) would be the best instrument for the study of particles physics at energies from 100 GeV to several TeV where a lot of new physics was expected, including the dark matter. Following the discovery of the Higgs boson at LHC (and nothing else), the physics community has been actively considering various approaches to building a Higgs factories for precision measurement of the Higgs properties, among them there are several proposals of photon colliders (PC). In this paper, following a brief discussion of general situation in particles physics and the place of the photon collider among candidates for future colliders, I give an overview of photon colliders based on linear colliders ILC and CLIC and of more recently proposed photon-collider Higgs factories (with no e+e− collision option) based on recirculation linacs in ring tunnels.
Abstract
Using the 1.32
$$\hbox {pb}^{-1}$$
pb
-
1
statistics collected at the
$$J/\psi $$
J
/
ψ
peak with the KEDR detector at the VEPP-4M
$$e^{+}e^{-\, }$$
e
+
e
-
collider, we measured the ...branching fractions of
$$J/\psi $$
J
/
ψ
meson decays to the final states 2(
$$\pi ^{+}\pi ^{-})\pi ^{0}$$
π
+
π
-
)
π
0
,
$$K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$
K
+
K
-
π
+
π
-
π
0
, 2(
$$\pi ^{+}\pi ^{-})$$
π
+
π
-
)
and
$$K^{+}K^{-}\pi ^{+}\pi ^{-}$$
K
+
K
-
π
+
π
-
. The results obtained for the decays
$$J/\psi \rightarrow $$
J
/
ψ
→
2(
$$\pi ^{+}\pi ^{-})\pi ^{0}$$
π
+
π
-
)
π
0
,
$$J/\psi \rightarrow K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$
J
/
ψ
→
K
+
K
-
π
+
π
-
π
0
contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.
Synopsis The relativistic intense-field ionization of heavy hydrogenlike ions is investigated. The investigation is performed by numerical solving of the time-dependent Dirac equation. The ...interaction of intense laser pulses with ions is considered beyond the dipole approximation. As an example, the ionization probabilities of the hydrogenlike tin ion exposed to a strong laser field are calculated.
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