scholarly journals Search for the doubly charmed baryon $$ {\varXi}_{cc}^{+} $$ in the $$ {\varXi}_c^{+}{\pi}^{-}{\pi}^{+} $$ final state

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
◽  
R. Aaij ◽  
A. S. W. Abdelmotteleb ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
...  
Keyword(s):  
Invariant Mass ◽  
Production Cross ◽  
Mass Range ◽  
Invariant Mass Spectrum ◽  
Proton Collision ◽  
Final State ◽  
Momentum Range ◽  
Charmed Baryon ◽  
Systematic Uncertainties ◽  
Standard Deviations

Abstract A search for the doubly charmed baryon $$ {\varXi}_{cc}^{+} $$ Ξ cc + is performed in the $$ {\varXi}_c^{+}{\pi}^{-}{\pi}^{+} $$ Ξ c + π − π + invariant-mass spectrum, where the $$ {\varXi}_c^{+} $$ Ξ c + baryon is reconstructed in the pK−π+ final state. The study uses proton-proton collision data collected with the LHCb detector at a centre- of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fb−1. No significant signal is observed in the invariant-mass range of 3.4–3.8 GeV/c2. Upper limits are set on the ratio of branching fractions multiplied by the production cross-section with respect to the $$ {\varXi}_{cc}^{++} $$ Ξ cc + + → ($$ {\varXi}_c^{+} $$ Ξ c + → pK−π+)π+ decay for different $$ {\varXi}_{cc}^{+} $$ Ξ cc + mass and lifetime hypotheses in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2.5 to 25 GeV/c. The results from this search are combined with a previously published search for the $$ {\varXi}_{cc}^{+} $$ Ξ cc + →$$ {\varLambda}_c^{+} $$ Λ c + K−π+ decay mode, yielding a maximum local significance of 4.0 standard deviations around the mass of 3620 MeV/c2, including systematic uncertainties. Taking into account the look-elsewhere effect in the 3.5–3.7 GeV/c2 mass window, the combined global significance is 2.9 standard deviations including systematic uncertainties.

scholarly journals Search for the doubly charmed baryon $$\Xi_{cc}^+$$

2019 ◽  
Vol 63 (2) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Production Cross ◽  
Branching Fraction ◽  
Mass Range ◽  
Proton Collision ◽  
Final State ◽  
Momentum Range ◽  
Proton Proton ◽  
Charmed Baryon ◽  
Upper Limits ◽  
Lhcb Detector

AbstractA search for the doubly charmed baryon $$\Xi_{cc}^+$$Ξcc+ is performed through its decay to the $$\Lambda_c^ + {K^ -}{\pi ^ +}$$Λc+K−π+ final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb−1. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the $$\Xi_{cc}^+$$Ξcc+ production cross-section times the branching fraction to that of $$\Lambda_c^ + $$Λc+ and $$\Xi_{cc}^{+ +}$$Ξcc++ baryons. The limits are determined as functions of the $$\Xi_{cc}^+$$Ξcc+ mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.

scholarly journals Search for the doubly charmed baryon Ω+cc

2021 ◽  
Vol 64 (10) ◽  
Author(s):  
◽  
R. Aaij ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Production Cross ◽  
Branching Fraction ◽  
Mass Range ◽  
Proton Collision ◽  
Centre Of Mass ◽  
Momentum Range ◽  
Proton Proton ◽  
Charmed Baryon ◽  
Upper Limits ◽  
Proton Proton Collision

AbstractA search for the doubly charmed baryon Ω cc + with the decay mode Ω cc + → Ξ c + K−π+ is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb−1. No significant signal is observed within the invariant mass range of 3.6 to 4.0GeV/c2. Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the Ω cc + → Ξ c + K−π+ decay with respect to the $$\Xi _{cc}^{ + + } \to \Lambda _c^ + {K^ - }{\pi ^ + }{\pi ^ + }$$ Ξ c c + + → Λ c + K − π + π + decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for different hypotheses on the Ω cc + mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/c.

scholarly journals Search for the doubly heavy $$ {\Xi}_{bc}^0 $$ baryon via decays to D0pK−

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Production Cross ◽  
Branching Fraction ◽  
Mass Range ◽  
Proton Collision ◽  
Centre Of Mass ◽  
Final State ◽  
Proton Proton ◽  
Upper Limits ◽  
Proton Proton Collision ◽  
Momentum Region

Abstract A search for the doubly heavy $$ {\Xi}_{bc}^0 $$ Ξ bc 0 baryon using its decay to the D0pK– final state is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb−1. No significant signal is found in the invariant mass range from 6.7 to 7.2 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the $$ {\Xi}_{bc}^0 $$ Ξ bc 0 production cross-section times its branching fraction to D0pK− relative to that of the $$ {\Lambda}_b^0\to {D}^0{pK}^{-} $$ Λ b 0 → D 0 pK − decay. The limits are set as a function of the $$ {\Xi}_{bc}^0 $$ Ξ bc 0 mass and lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and in the transverse momentum region from 5 to 25 GeV/c. Upper limits range from 1.7 × 10−2 to 3.0 × 10−1 for the considered $$ {\Xi}_{bc}^0 $$ Ξ bc 0 mass and lifetime hypotheses.

STUDY OF THE DIJET INVARIANT MASS IN W + JETS EVENTS BY THE DØ COLLABORATION

2012 ◽  
Vol 27 (01) ◽  
pp. 1230002
Author(s):  
JADRANKA SEKARIC
Keyword(s):  
Mass Spectrum ◽  
Invariant Mass ◽  
Experimental Verification ◽  
Hadron Collider ◽  
Mass Range ◽  
Invariant Mass Spectrum ◽  
Dijet Production ◽  
Dijet Mass ◽  
Two Jets ◽  
Recent Claim

The recent claim by the CDF Collaboration of a possible anomalous dijet resonance in their data required experimental verification from other hadron collider experiments. We present a study of the dijet invariant mass spectrum in events with two jets produced in association with a W→ℓν boson at the DØ experiment. We investigate the dijet mass range between 110 GeV /c2 and 170 GeV /c2 and find no evidence for any resonant dijet production.

scholarly journals Search for heavy neutral leptons in $$W^+\rightarrow \mu ^{+}\mu ^{\pm }\, \text {jet}$$ decays

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Mass Range ◽  
Lepton Number ◽  
Heavy Neutrino ◽  
Proton Collision ◽  
Final State ◽  
Data Set ◽  
Proton Proton ◽  
Upper Limits ◽  
The Standard Model ◽  
Proton Proton Collision

AbstractA search is performed for heavy neutrinos in the decay of a W boson into two muons and a jet. The data set corresponds to an integrated luminosity of approximately $$3.0\, \text {fb} ^{-1} $$ 3.0 fb - 1 of proton–proton collision data at centre-of-mass energies of 7 and $$8\, \text {TeV} $$ 8 TeV collected with the LHCb experiment. Both same-sign and opposite-sign muons in the final state are considered. Data are found to be consistent with the expected background. Upper limits on the coupling of a heavy neutrino with the Standard Model neutrino are set at $$95\%$$ 95 % confidence level in the heavy-neutrino mass range from 5 to $$50\, \text {GeV/}c^2 $$ 50 GeV/ c 2 . These are of the order of $$10^{-3}$$ 10 - 3 for lepton-number-conserving decays and of the order of $$10^{-4}$$ 10 - 4 for lepton-number-violating heavy-neutrino decays.

scholarly journals Measurement of the t$$ \overline{t} $$t$$ \overline{t} $$ production cross section in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
◽  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Cross Section ◽  
Top Quark ◽  
Production Cross Section ◽  
Production Cross ◽  
Atlas Detector ◽  
Proton Collision ◽  
Atlas Collaboration ◽  
Top Quark Production ◽  
Quark Production ◽  
Standard Deviations

Abstract A measurement of four-top-quark production using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider corresponding to an integrated luminosity of 139 fb−1 is presented. Events are selected if they contain a single lepton (electron or muon) or an opposite-sign lepton pair, in association with multiple jets. The events are categorised according to the number of jets and how likely these are to contain b-hadrons. A multivariate technique is then used to discriminate between signal and background events. The measured four-top-quark production cross section is found to be $$ {26}_{-15}^{+17} $$ 26 − 15 + 17 fb, with a corresponding observed (expected) significance of 1.9 (1.0) standard deviations over the background-only hypothesis. The result is combined with the previous measurement performed by the ATLAS Collaboration in the multilepton final state. The combined four-top-quark production cross section is measured to be $$ {24}_{-6}^{+7} $$ 24 − 6 + 7 fb, with a corresponding observed (expected) signal significance of 4.7 (2.6) standard deviations over the background-only predictions. It is consistent within 2.0 standard deviations with the Standard Model expectation of 12.0 ± 2.4 fb.

scholarly journals Search for Excited Spin-3/2 Neutrinos at LHeC

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
A. Ozansoy ◽  
V. Arı ◽  
V. Çetinkaya
Keyword(s):  
Invariant Mass ◽  
Cross Section ◽  
Decay Mode ◽  
Production Cross Section ◽  
Production Cross ◽  
Gauge Bosons ◽  
Final State ◽  
Mass Distributions ◽  
Contour Plots ◽  
Single Production

We study the potential of the nextepcollider, namely, LHeC, with two optionss=1.3 TeV ands=1.98 TeV, to search for excited spin-1/2 and spin-3/2 neutrinos. We calculate the single production cross-section of excited spin-1/2 and spin-3/2 neutrinos according to their effective currents describing their interactions between gauge bosons and SM leptons. We choose theν⋆→eWdecay mode of excited neutrinos andW→jjdecay mode ofW-boson for the analysis. We put some kinematical cuts for the final state detectable particles and plot the invariant mass distributions for signal and the corresponding backgrounds. In order to obtain accessible limits for excited neutrino couplings, we show thef-f′andciV-ciAcontour plots for excited spin-1/2 and excited spin-3/2 neutrinos, respectively.

scholarly journals The W mass and width measurement challenge at FCC-ee

2021 ◽  
Vol 136 (12) ◽  
Author(s):  
Paolo Azzurri
Keyword(s):  
W Boson ◽  
Production Cross ◽  
Boson Mass ◽  
Hadronic Decays ◽  
Reconstruction Method ◽  
Final State ◽  
Systematic Uncertainties ◽  
Statistical Precision ◽  
Pair Production Cross Section ◽  
The Impact

AbstractThe FCC-ee physics program will deliver two complementary top-notch precision determinations of the W boson mass, and width. The first and main measurement relies on the rapid rise of the W-pair production cross section near its kinematic threshold. This method is extremely simple and clean, involving only the selection and counting of events, in all different decay channels. An optimal threshold-scan strategy with a total integrated luminosity of $$12\,\mathrm{ab}^{-1}$$ 12 ab - 1 shared on energy points between 157 and 163 GeV will provide a statistical uncertainty on the W mass of 0.5 MeV and on the W width of 1.2 MeV. For these measurements, the goal of keeping the impact of systematic uncertainties below the statistical precision will be demanding, but feasible. The second method exploits the W-pair final state reconstruction and kinematic fit, making use of events with either four jets or two jets, one lepton and missing energy. The projected statistical precision of the second method is similar to the first method’s, with uncertainties of $$\sim 0.5$$ ∼ 0.5 (1) MeV for the W mass (width), employing W-pair data collected at the production threshold and at 240–365 GeV. For the kinematic reconstruction method, the final impact of systematic uncertainties is currently less clear, in particular uncertainties connected to the modeling of the W hadronic decays. The use and interplay of Z$$\gamma $$ γ and ZZ events, reconstructed and fitted with the same techniques as the WW events, will be important for the extraction of W mass measurements with data at the higher 240 and 365 GeV energies.

scholarly journals Evidence for $$t\bar{t}t\bar{t}$$ production in the multilepton final state in proton–proton collisions at $$\sqrt{s}=13$$ $$\text {TeV}$$ with the ATLAS detector

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Top Quark ◽  
Production Cross ◽  
Atlas Detector ◽  
Proton Collision ◽  
Final State ◽  
Proton Proton ◽  
Top Quark Production ◽  
Quark Production ◽  
Proton Proton Collision ◽  
Multivariate Discriminant

AbstractA search is presented for four-top-quark production using an integrated luminosity of 139 fb$$^{-1}$$ - 1 of proton–proton collision data at a centre-of-mass energy of $$13~\text {TeV}$$ 13 TeV collected by the ATLAS detector at the LHC. Events are selected if they contain a same-sign lepton pair or at least three leptons (electrons or muons). Jet multiplicity, jet flavour and event kinematics are used to separate signal from the background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The four-top-quark production cross section is measured to be $$24^{+7}_{-6}$$ 24 - 6 + 7  fb. This corresponds to an observed (expected) significance with respect to the background-only hypothesis of 4.3 (2.4) standard deviations and provides evidence for this process.

scholarly journals Search for heavy diboson resonances in semileptonic final states in pp collisions at $$\sqrt{s}=13$$ TeV with the ATLAS detector

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Cross Sections ◽  
Production Cross ◽  
Vector Boson ◽  
Hadron Collider ◽  
Gluon Fusion ◽  
Mass Range ◽  
Atlas Detector ◽  
Proton Collision ◽  
Final States ◽  
Heavy Resonances

AbstractThis paper reports on a search for heavy resonances decaying into WW, ZZ or WZ using proton–proton collision data at a centre-of-mass energy of $$\sqrt{s}=13$$ s = 13  TeV. The data, corresponding to an integrated luminosity of 139 $$\mathrm{fb}^{1}$$ fb 1 , were recorded with the ATLAS detector from 2015 to 2018 at the Large Hadron Collider. The search is performed for final states in which one W or Z boson decays leptonically, and the other W boson or Z boson decays hadronically. The data are found to be described well by expected backgrounds. Upper bounds on the production cross sections of heavy scalar, vector or tensor resonances are derived in the mass range 300–5000 GeV within the context of Standard Model extensions with warped extra dimensions or including a heavy vector triplet. Production through gluon–gluon fusion, Drell–Yan or vector-boson fusion are considered, depending on the assumed model.

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