The Large Hadron–Electron Collider at the HL-LHC Aksakal, H; Alekhin, S; Allport, P P ...
Journal of physics. G, Nuclear and particle physics,
11/2021, Letnik:
48, Številka:
11
Journal Article
The first measurement of lepton-jet momentum imbalance and azimuthal correlation in lepton-proton scattering at high momentum transfer is presented. These data, taken with the H1 detector at HERA, ...are corrected for detector effects using an unbinned machine learning algorithm (multifold), which considers eight observables simultaneously in this first application. The unfolded cross sections are compared with calculations performed within the context of collinear or transverse-momentum-dependent factorization in quantum chromodynamics as well as Monte Carlo event generators.
The strong coupling constant
α
s
is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic
ep
scattering (DIS) measured at HERA by the H1 collaboration using ...next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of
α
s
(
m
Z
)
at the
Z
-boson mass
m
Z
are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be
α
s
(
m
Z
)
=
0.1157
(
20
)
exp
(
29
)
th
. Complementary,
α
s
(
m
Z
)
is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value
α
s
(
m
Z
)
=
0.1142
(
28
)
tot
obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.
The H1 Collaboration reports the first measurement of the 1-jettiness event shape observable
τ
1
b
in neutral-current deep-inelastic electron-proton scattering (DIS). The observable
τ
1
b
is ...equivalent to a thrust observable defined in the Breit frame. The data sample was collected at the HERA
ep
collider in the years 2003–2007 with center-of-mass energy of
s
=
319
GeV
, corresponding to an integrated luminosity of 351.1
pb
-
1
. Triple differential cross sections are provided as a function of
τ
1
b
, event virtuality
Q
2
, and inelasticity
y
, in the kinematic region
Q
2
>
150
GeV
2
. Single differential cross sections are provided as a function of
τ
1
b
in a limited kinematic range. Double differential cross sections are measured, in contrast, integrated over
τ
1
b
and represent the inclusive neutral-current DIS cross section measured as a function of
Q
2
and
y
. The data are compared to a variety of predictions and include long-standing and more recent Monte Carlo event generators, predictions in fixed-order perturbative QCD where calculations up to
O
(
α
s
3
)
are available for
τ
1
b
or inclusive DIS, and resummed predictions at next-to-leading logarithmic accuracy matched to fixed order predictions at
O
(
α
s
2
)
. These comparisons reveal sensitivity of the 1-jettiness observable to QCD parton shower and resummation effects, as well as the modeling of hadronization and fragmentation. Within their range of validity, the fixed-order predictions provide a good description of the data. Monte Carlo event generators are predictive over the full measured range and hence their underlying models and parameters can be constrained by comparing to the presented data.
The H1 Collaboration at HERA reports the first measurement of groomed event shape observables in deep inelastic electron-proton scattering (DIS) at
s
=
319
GeV, using data recorded between the years ...2003 and 2007 with an integrated luminosity of 351
pb
-
1
. Event shapes provide incisive probes of perturbative and non-perturbative QCD. Grooming techniques have been used for jet measurements in hadronic collisions; this paper presents the first application of grooming to DIS data. The analysis is carried out in the Breit frame, utilizing the novel Centauro jet clustering algorithm that is designed for DIS event topologies. Events are required to have squared momentum-transfer
Q
2
>
150
GeV
2
and inelasticity
0.2
<
y
<
0.7
. We report measurements of the production cross section of groomed event 1-jettiness and groomed invariant mass for several choices of grooming parameter. Monte Carlo model calculations and analytic calculations based on Soft Collinear Effective Theory are compared to the measurements.
Beam test results of NDL Low Gain Avalanche Detectors (LGAD) Xiao, S.; Alderweireldt, S.; Ali, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2021, Letnik:
989
Journal Article
Recenzirano
Odprti dostop
A High-Granularity Timing Detector (HGTD) is proposed based on the Low-Gain Avalanche Detector (LGAD) for the ATLAS experiment to satisfy the time resolution requirement for the up-coming High ...Luminosity at LHC (HL-LHC). We report on beam test results for two proto-types LGADs (BV60 and BV170) developed for the HGTD. Such modules were manufactured by the Institute of High Energy Physics (IHEP) of Chinese Academy of Sciences (CAS) collaborated with Novel Device Laboratory (NDL) of the Beijing Normal University. The beam tests were performed with 5 GeV electron beam at DESY. The timing performance of the LGADs was compared to a trigger counter consisting of a quartz bar coupled to a SiPM readout while extracting reference SiPM by fitting with a Gaussian function. The time resolution was obtained as 41 ps and 63 ps for the BV60 and the BV170, respectively.
A
bstract
The cross section of the diffractive process
e
+
p
→
e
+
Xp
is measured at a centre-of-mass energy of 318 GeV, where the system
X
contains at least two jets and the leading final state ...proton
p
is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction with photon virtualities
Q
2
<
2 GeV
2
and in deep-inelastic scattering with 4 GeV
2
< Q
2
<
80 GeV
2
. The results are compared to next- to-leading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deep-inelastic scattering.
Abstract Exclusive photoproduction of $${{\rho ^0}} (770)$$ ρ 0 ( 770 ) mesons is studied using the H1 detector at the ep collider HERA. A sample of about 900,000 events is used to measure single- ...and double-differential cross sections for the reaction $$\gamma p \rightarrow \pi ^{+}\pi ^{-}Y$$ γ p → π + π - Y . Reactions where the proton stays intact ( $${{{m_Y}} {=}m_p}$$ m Y = m p ) are statistically separated from those where the proton dissociates to a low-mass hadronic system ( $$m_p{<}{{m_Y}} {<}10~{{\text {GeV}}} $$ m p < m Y < 10 GeV ). The double-differential cross sections are measured as a function of the invariant mass $$m_{\pi \pi }$$ m π π of the decay pions and the squared 4-momentum transfer t at the proton vertex. The measurements are presented in various bins of the photon–proton collision energy $${{W_{\gamma p}}} $$ W γ p . The phase space restrictions are $$0.5\le m_{\pi \pi } \le 2.2~{{\text {GeV}}} $$ 0.5 ≤ m π π ≤ 2.2 GeV , $$\vert t\vert \le 1.5~{{\text {GeV}^2}} $$ | t | ≤ 1.5 GeV 2 , and $$20 \le W_{\gamma p} \le 80~{{\text {GeV}}} $$ 20 ≤ W γ p ≤ 80 GeV . Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the $${m_{\pi \pi }}$$ m π π dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the $${{\rho ^0}} (770)$$ ρ 0 ( 770 ) meson mass and width at $$m_\rho = 770.8{}^{+2.6}_{-2.7}~({\text {tot.}})~{{\text {MeV}}} $$ m ρ = 770.8 - 2.7 + 2.6 ( tot. ) MeV and $$\Gamma _\rho = 151.3 {}^{+2.7}_{-3.6}~({\text {tot.}})~{{\text {MeV}}} $$ Γ ρ = 151.3 - 3.6 + 2.7 ( tot. ) MeV , respectively. The model is used to extract the $${{\rho ^0}} (770)$$ ρ 0 ( 770 ) contribution to the $$\pi ^{+}\pi ^{-}$$ π + π - cross sections and measure it as a function of t and $${W_{\gamma p}}$$ W γ p . In a Regge asymptotic limit in which one Regge trajectory $$\alpha (t)$$ α ( t ) dominates, the intercept $$\alpha (t{=}0) = 1.0654\ {}^{+0.0098}_{-0.0067}~({\text {tot.}})$$ α ( t = 0 ) = 1.0654 - 0.0067 + 0.0098 ( tot. ) and the slope $$\alpha ^\prime (t{=}0) = 0.233 {}^{+0.067 }_{-0.074 }~({\text {tot.}}) ~{{\text {GeV}^{-2}}} $$ α ′ ( t = 0 ) = 0.233 - 0.074 + 0.067 ( tot. ) GeV - 2 of the t dependence are extracted for the case $$m_Y{=}m_p$$ m Y = m p .
A
bstract
A measurement is presented of single- and double-differential dijet cross sections in diffractive deep-inelastic
ep
scattering at HERA using data collected by the H1 experiment ...corresponding to an integrated luminosity of 290 pb
−1
. The investigated phase space is spanned by the photon virtuality in the range of 4
< Q
2
<
100 GeV
2
and by the fractional proton longitudinal momentum loss
x
ℙ
<
0
.
03. The resulting cross sections are compared with next-to-leading order QCD predictions based on diffractive parton distribution functions and the value of the strong coupling constant is extracted.
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