Abstract
Superconducting technology makes it possible to build a high
energy e
+
e
-
linear collider with energy recovery (ERLC) and
reusable beams. To avoid parasitic collisions inside the linacs, a
...twin (dual) LC is proposed. In this article, I consider the
principle scheme of the collider and estimate the achievable
luminosity, which is limited by collision effects and available
power. Such a collider can operate in a duty cycle (DC) and in a
continuous (CW) modes, if sufficient power. With current SC Nb
technology (
T
= 1.8 K,
f
RF
= 1.3 GHz, used for ILC) and with
power
P
= 100 MW, a luminosity
L
∼ 0.33 × 10
36
cm
-2
s
-1
is possible at the Higgs factory with
2
E
0
= 250 GeV. Using superconductors operating at 4.5 K with high
Q
0
values, such as Nb
3
Sn, and
f
RF
= 0.65 GHz, the
luminosity can reach
L
∼ 1.4 × 10
36
cm
-2
s
-1
at 2
E
E
0
= 250 GeV (with
P
= 100 MW) and
L
∼ 0.8 × 10
36
cm
-2
s
-1
at
2
E
0
= 500 GeV (with
P
= 150 MW), which is almost two
orders of magnitude greater than at the ILC, where the beams are
used only once. This technology requires additional efforts to
obtain the required parameters and reliably operation. Such a
collider would be the best machine for precision Higgs studies,
including the measurement of Higgs self-coupling.
We propose and demonstrate that a γγ collider with Wγγ≤12 GeV can be added to the European XFEL with a minimal disruption to its main program. High-energy photons will be obtained by Compton ...scattering of 0.5μm laser photons on the existing 17.5 GeV electron beams. Such a γγ collider would be an excellent place for the development and application of modern technologies: powerful lasers, optical cavities, superconducting linacs, and low-emittance electron sources—as well as training the next generation of accelerator physicists and engineers. The physics program would include spectroscopy of C=+ resonances in various JP states (b ,c , four-quark states, quark molecules and other exotica) in a mass range barely scratched by past and not covered by any current or planned experiments. Variable circular and linear polarizations will help in the determination of quantum numbers and measurement of polarization components of the γγ cross section (σ⊥, σ∥, σ0, σ2).
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
The discovery of the Higgs boson (and still nothing else) have triggered appearance of many proposals of Higgs factories for precision measurement of the Higgs properties. Among them there are ...several projects of photon colliders (PC) without e super(+)e super(-) in addition to PLC based on e super(+)e super(-) linear colliders ILC and CLIC. In this paper, following a brief discussion of Higgs factories physics program I give an overview of photon colliders based on linear colliders ILC and CLIC, and of the recently proposed photon-collider Higgs factories with no e super(+)e super(-) collision option based on recirculation linacs in ring tunnels.
Calibration of the absolute energy scale at high-energy photon ( gamma gamma , gamma ) colliders is discussed. The luminosity spectrum at photon colliders is broad and has a rather sharp high-energy ...edge, which can be used, for example, to measure the mass of the Higgs boson in the process gamma gamma arrow right H or masses of charged scalars by observing the cross-section threshold. In addition to the precise knowledge of the edge energy of the luminosity spectrum, it is even more important to have a way to calibrate the absolute energy scale of the detector. At first sight, Compton scattering itself provides a unique way to determine the beam energies and produce particles of known energies that could be used for detector calibration. The energy scale is given by the electron mass m sub(e) and laser photon energy omega sub(0). However, this does not work at realistic photon colliders due to large nonlinear effects in Compton scattering at the conversion region (xi super(2) ~ 0.3). It is argued that the process gamma e arrow right eZ sub(0) provides the best way to calibrate the energy scale of the detector, where the energy scale is given by m sub(Z).
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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