Abstract
The TOTEM collaboration has measured the elastic proton-proton differential cross section
$$\mathrm{d}\sigma /\mathrm{d}t$$
d
σ
/
d
t
at
$$\sqrt{s}=13$$
s
=
13
TeV LHC energy using ...dedicated
$$\beta ^{*}=90$$
β
∗
=
90
m beam optics. The Roman Pot detectors were inserted to 10
$$\sigma $$
σ
distance from the LHC beam, which allowed the measurement of the range 0.04 GeV
$$^{2}$$
2
; 4 GeV
$$^{2}$$
2
$$$$
in four-momentum transfer squared |
t
|. The efficient data acquisition allowed to collect about 10
$$^{9}$$
9
elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-|
t
| tail. The average nuclear slope has been found to be
$$B=(20.40 \pm 0.002^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$
B
=
(
20.40
±
0
.
002
stat
±
0
.
01
syst
)
GeV
$$^{-2}$$
-
2
in the |
t
|-range 0.04–0.2 GeV
$$^{2}$$
2
. The dip position is
$$|t_{\mathrm{dip}}|=(0.47 \pm 0.004^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$
|
t
dip
|
=
(
0.47
±
0
.
004
stat
±
0
.
01
syst
)
GeV
$$^{2}$$
2
. The differential cross section ratio at the bump vs. at the dip
$$R=1.77\pm 0.01^{\mathrm{stat}}$$
R
=
1.77
±
0
.
01
stat
has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Precise knowledge of the beam optics at the LHC is crucial to fulfill the physics goals of the TOTEM experiment, where the kinematics of the scattered protons is reconstructed with near-beam ...telescopes-so-called Roman pots (RP). Before being detected, the protons' trajectories are influenced by the magnetic fields of the accelerator lattice. Thus precise understanding of the proton transport is of key importance for the experiment. A novel method of optics evaluation is proposed which exploits kinematical distributions of elastically scattered protons observed in the RPs. Theoretical predictions, as well as Monte Carlo studies, show that the residual uncertainty of the optics estimation method is smaller than .
The TOTEM experiment at the LHC has performed the first measurement at
s
=
13
TeV
of the
ρ
parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at
t
=
0
, obtaining the ...following results:
ρ
=
0.09
±
0.01
and
ρ
=
0.10
±
0.01
, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the
ρ
measurement, combined with the TOTEM total cross-section measurements in an energy range larger than
10
TeV
(from 2.76 to
13
TeV
), has implied the exclusion of all the models classified and published by COMPETE. The
ρ
results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the
t
-channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state
t
-channel exchange is not of importance for the description of elastic scattering, the
ρ
value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-|
t
| reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton–proton cross-section measurement
σ
tot
=
(
110.3
±
3.5
)
mb
, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields
σ
tot
=
(
110.5
±
2.4
)
mb
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The TOTEM collaboration has measured the proton–proton total cross section at
s
=
13
TeV
with a luminosity-independent method. Using dedicated
β
∗
=
90
m
beam optics, the Roman Pots were inserted ...very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton–proton cross section is
σ
tot
=
(
110.6
±
3.4
) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections:
σ
el
=
(
31.0
±
1.7
)
mb
and
σ
inel
=
(
79.5
±
1.8
)
mb
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The TOTEM collaboration has measured the elastic proton-proton differential cross section
d
σ
/
d
t
at
s
=
13
TeV LHC energy using dedicated
β
∗
=
90
m beam optics. The Roman Pot detectors were ...inserted to 10
σ
distance from the LHC beam, which allowed the measurement of the range 0.04 GeV
2
; 4 GeV
2
in four-momentum transfer squared |
t
|. The efficient data acquisition allowed to collect about 10
9
elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-|
t
| tail. The average nuclear slope has been found to be
B
=
(
20.40
±
0
.
002
stat
±
0
.
01
syst
)
GeV
-
2
in the |
t
|-range 0.04–0.2 GeV
2
. The dip position is
|
t
dip
|
=
(
0.47
±
0
.
004
stat
±
0
.
01
syst
)
GeV
2
. The differential cross section ratio at the bump vs. at the dip
R
=
1.77
±
0
.
01
stat
has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The TOTEM experiment at the CERN LHC has measured elastic proton–proton scattering at the centre-of-mass energy
s
=
8
TeV and four-momentum transfers squared, |
t
|, from
6
×
10
-
4
to 0.2 GeV
2
. ...Near the lower end of the
t
-interval the differential cross-section is sensitive to the interference between the hadronic and the electromagnetic scattering amplitudes. This article presents the elastic cross-section measurement and the constraints it imposes on the functional forms of the modulus and phase of the hadronic elastic amplitude. The data exclude the traditional Simplified West and Yennie interference formula that requires a constant phase and a purely exponential modulus of the hadronic amplitude. For parametrisations of the hadronic modulus with second- or third-order polynomials in the exponent, the data are compatible with hadronic phase functions giving either central or peripheral behaviour in the impact parameter picture of elastic scattering. In both cases, the
ρ
-parameter is found to be
0.12
±
0.03
. The results for the total hadronic cross-section are
σ
tot
=
(
102.9
±
2.3
)
mb and
(
103.0
±
2.3
)
mb for central and peripheral phase formulations, respectively. Both are consistent with previous TOTEM measurements.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The TOTEM collaboration has measured the proton-proton total cross section at √s=8 TeV using a luminosity-independent method. In LHC fills with dedicated beam optics, the Roman pots have been ...inserted very close to the beam allowing the detection of ~90% of the nuclear elastic scattering events. Simultaneously the inelastic scattering rate has been measured by the T1 and T2 telescopes. By applying the optical theorem, the total proton-proton cross section of (101.7±2.9) mb has been determined, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: σ(el)=(27.1±1.4) mb; σ(inel)=(74.7±1.7) mb.
The physics programme of the TOTEMexperiment requires the detection of very forward protons scattered by only a few microradians out of the LHC beams. For this purpose, stacks of planar Silicon ...detectors have been mounted in moveable near-beam telescopes (Roman Pots) located along the beamline on both sides of the interaction point. In order to maximise the proton acceptance close to the beams, the dead space at the detector edge had to be minimised. During the detector prototyping phase, different sensor technologies and designs have been explored. A reduction of the dead space to less than 50 mu m has been accomplished with two novel silicon detector technologies: one with the Current Terminating Structure (CTS) design and one based on the 3D edge manufacturing. This paper describes performance studies on prototypes of these detectors, carried out in 2004 in a fixed-target muon beam at CERN's SPS accelerator. In particular, the efficiency and accuracy in the vicinity of the beam-facing edges are discussed.
We report the observation of single top-quark production using 3.2 fb(-1) of ppover collision data with sqrts=1.96 TeV collected by the Collider Detector at Fermilab. The significance of the ...observed data is 5.0 standard deviations, and the expected sensitivity for standard model production and decay is in excess of 5.9 standard deviations. Assuming m(t) = 175 GeV/c(2), we measure a cross section of 2.3(-0.5);(+0.6)(stat + syst) pb, extract the CKM matrix-element value |V(tb)| = 0.91 + or - 0.11(stat + syst) + or - 0.07(theory), and set the limit |V(tb)| > 0.71 at the 95% C.L.
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