Measurements of the production of forward jets from transversely polarized proton collisions at s=500 GeV conducted at the Relativistic Heavy Ion Collider (RHIC) are reported. Our measured jet cross ...section is consistent with hard scattering expectations. Our measured analyzing power for forward jet production is small and positive, and provides constraints on the Sivers functions that are related to partonic orbital angular momentum through theoretical models.
Angular analysis of the rare decay Bs0→ ϕμ+μ Ackernley, T.; Balagura, V.; Belyaev, I. ...
The journal of high energy physics,
11/2021, Letnik:
2021, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
An angular analysis of the rare decay
B
s
0
→ ϕμ
+
μ
−
is presented, using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, ...corresponding to an integrated luminosity of 8.4 fb
−
1
. The observables describing the angular distributions of the decay
B
s
0
→ ϕμ
+
μ
−
are determined in regions of
q
2
, the square of the dimuon invariant mass. The results are consistent with Standard Model predictions.
Mesons comprising a beauty quark and strange quark can oscillate between particle (Bs0) and antiparticle (B¯s0) flavour eigenstates, with a frequency given by the mass difference between heavy and ...light mass eigenstates, Δms. Here we present a measurement of Δms using Bs0→Ds−π+ decays produced in proton–proton collisions collected with the LHCb detector at the Large Hadron Collider. The oscillation frequency is found to be Δms = 17.7683 ± 0.0051 ± 0.0032 ps−1, where the first uncertainty is statistical and the second is systematic. This measurement improves on the current Δms precision by a factor of two. We combine this result with previous LHCb measurements to determine Δms = 17.7656 ± 0.0057 ps−1, which is the legacy measurement of the original LHCb detector.The LHCb collaboration reports an improved measurement of the oscillation frequency of mesons consisting of a bottom quark and strange quark, which is then combined with previous results.
Precision measurement of the Ξcc++ mass Alexander, M.; Alves, A. A.; Baryshnikov, F. ...
The journal of high energy physics,
02/2020, Letnik:
2020, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A
bstract
A measurement of the
Ξ
cc
+
+
mass is performed using data collected by the LHCb experiment between 2016 and 2018 in
pp
collisions at a centre-of-mass energy of 13 TeV, corresponding to an ...integrated luminosity of 5
.
6 fb
−
1
. The
Ξ
cc
+
+
candidates are reconstructed via the decay modes
Ξ
cc
+
+
→
Λ
c
+
K
−
π
+
π
+
and
Ξ
cc
+
+
→
Ξ
c
+
π
+
. The result, 3621
.
55
±
0
.
23 (stat)
±
0
.
30 (syst) MeV/
c
2
, is the most precise measurement of the
Ξ
cc
+
+
mass to date.
Precision measurement of the Bc+ meson mass Alexander, M.; Alkhazov, G.; Aslanides, E. ...
The journal of high energy physics,
07/2020, Letnik:
2020, Številka:
7
Journal Article
Recenzirano
Odprti dostop
A
bstract
A precision measurement of the
B
c
+
meson mass is performed using proton- proton collision data collected with the LHCb experiment at centre-of-mass energies of 7
,
8 and 13 TeV, ...corresponding to a total integrated luminosity of 9
.
0 fb
−
1
. The
B
c
+
mesons are reconstructed via the decays
B
c
+
→ J/ψπ
+
,
B
c
+
→ J/ψπ
+
π
−
π
+
,
B
c
+
→
J
/
ψp
p
¯
π
+
,
B
c
+
→
J
/
ψ
D
s
+
,
B
c
+
→ J/ψ D
0
K
+
and
B
c
+
→
B
s
0
π
+
. Combining the results of the individual decay channels, the
B
c
+
mass is measured to be 6274
.
47
±
0
.
27 (stat)
±
0
.
17 (syst) MeV
/c
2
. This is the most precise measurement of the
B
c
+
mass to date. The difference between the
B
c
+
and
B
s
0
meson masses is measured to be 907
.
75
±
0
.
37 (stat)
±
0
.
27 (syst) MeV
/c
.
A
bstract
The differential cross-section of prompt inclusive production of long-lived charged particles in proton-proton collisions is measured using a data sample recorded by the LHCb experiment at ...a centre-of-mass energy of
s
= 13 TeV. The data sample, collected with an unbiased trigger, corresponds to an integrated luminosity of 5
.
4 nb
−
1
. The differential cross-section is measured as a function of transverse momentum and pseudorapidity in the ranges
p
T
∈ 80
,
10 000) MeV
/c
and
η
∈ 2
.
0
,
4
.
8) and is determined separately for positively and negatively charged particles. The results are compared with predictions from various hadronic-interaction models.
A
bstract
The production cross-section of the
χ
c
1
(3872) state relative to the
ψ
(2
S
) meson is measured using proton-proton collision data collected with the LHCb experiment at centre-of-mass ...energies of
s
= 8 and 13 TeV, corresponding to integrated luminosities of 2.0 and 5.4 fb
−
1
, respectively. The two mesons are reconstructed in the
J/ψπ
+
π
−
final state. The ratios of the prompt and nonprompt
χ
c
1
(3872) to
ψ
(2
S
) production cross-sections are measured as a function of transverse momentum,
p
T
, and rapidity,
y
, of the
χ
c
1
(3872) and
ψ
(2
S
) states, in the kinematic range 4
< p
T
<
20 GeV/
c
and 2
.
0
< y <
4
.
5. The prompt ratio is found to increase with
p
T
, independently of
y
. For the prompt component, the double ratio of the
χ
c
1
(3872) and
ψ
(2
S
) production cross-sections between 13 and 8 TeV is observed to be consistent with unity, independent of
p
T
and centre-of-mass energy.
PDF
