Date

Event-shape and multiplicity dependence of freeze-out radii in pp collisions at $\sqrt{{\textit s}}=7$ TeV

The ALICE collaboration Acharya, Shreyasi ; Torales - Acosta, Fernando ; Adamova, Dagmar ; et al.
JHEP 09 (2019) 108, 2019.
Inspire Record 1714695 DOI 10.17182/hepdata.91128

Two-particle correlations in high-energy collision experiments enable the extraction of particle source radii by using the Bose-Einstein enhancement of pion production at low relative momentum $q\propto 1/R$. It was previously observed that in $\rm{p}\rm{p}$ collisions at $\sqrt{s}=7$ TeV the average pair transverse momentum $k_{\rm T}$ range of such analyses is limited due to large background correlations which were attributed to mini-jet phenomena. To investigate this further, an event-shape dependent analysis of Bose-Einstein correlations for pion pairs is performed in this work. By categorizing the events by their transverse sphericity $S_{\rm T}$ into spherical $(S_\textrm{T}>0.7)$ and jet-like $(S_\textrm{T}<0.3)$ events a method was developed that allows for the determination of source radii for much larger values of $k_{\rm T}$ for the first time. Spherical events demonstrate little or no background correlations while jet-like events are dominated by them. This observation agrees with the hypothesis of a mini-jet origin of the non-femtoscopic background correlations and gives new insight into the physics interpretation of the $k_{\rm T}$ dependence of the radii. The emission source size in spherical events shows a substantially diminished $k_{\rm T}$ dependence, while jet-like events show indications of a negative trend with respect to $k_{\rm T}$ in the highest multiplicity events. Regarding the emission source shape, the correlation functions for both event sphericity classes show good agreement with an exponential shape, rather than a Gaussian one.

18 data tables

Opposite-sign pion pair correlation functions in data for sphericity S_{T} < 0.3 (jet-like events).

Opposite-sign pion pair correlation functions in PYTHIA simulations for sphericity S_{T} < 0.3 (jet-like events).

Opposite-sign pion pair correlation functions in data for sphericity S_{T} > 0.7 (spherical events).

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Measurement of electroweak WZ boson production and search for new physics in WZ $+$ two jets events in pp collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett.B 795 (2019) 281-307, 2019.
Inspire Record 1713565 DOI 10.17182/hepdata.89174

A measurement of WZ electroweak (EW) vector boson scattering is presented. The measurement is performed in the leptonic decay modes WZ $\to$ $\ell\nu\ell'\ell'$, where $\ell, \ell' = $ e, $\mu$. The analysis is based on a data sample of proton-proton collisions at $\sqrt{s} =$ 13 TeV at the LHC collected with the CMS detector and corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The WZ plus two jet production cross section is measured in fiducial regions with enhanced contributions from EW production and found to be consistent with standard model predictions. The EW WZ production in association with two jets is measured with an observed (expected) significance of 2.2 (2.5) standard deviations. Constraints on charged Higgs boson production and on anomalous quartic gauge couplings in terms of dimension-eight effective field theory operators are also presented.

5 data tables

The measured WZ cross section in the tight EWK fiducial region.

The measured WZ cross section in the loose EWK fiducial region.

The measured EWK WZ scale factor (mu) in the tight EWK fiducial region. The uncertainty is the combined stastical uncertianty and the systematic uncertainty including experimental and theortical sources

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Measurement of the $t\bar{t}Z$ and $t\bar{t}W$ cross sections in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.D 99 (2019) 072009, 2019.
Inspire Record 1713423 DOI 10.17182/hepdata.88175

A measurement of the associated production of a top-quark pair ($t\bar{t}$) with a vector boson ($W$, $Z$) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented, using $36.1$ fb$^{-1}$ of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. Events are selected in channels with two same- or opposite-sign leptons (electrons or muons), three leptons or four leptons, and each channel is further divided into multiple regions to maximize the sensitivity of the measurement. The $t\bar{t}Z$ and $t\bar{t}W$ production cross sections are simultaneously measured using a combined fit to all regions. The best-fit values of the production cross sections are $\sigma_{t\bar{t}Z} = 0.95 \pm 0.08_{\mathrm{stat.}} \pm 0.10_{\mathrm{syst.}}$ pb and $\sigma_{t\bar{t}W} = 0.87 \pm 0.13_{\mathrm{stat.}} \pm 0.14_{\mathrm{syst.}}$ pb in agreement with the Standard Model predictions. The measurement of the $t\bar{t}Z$ cross section is used to set constraints on effective field theory operators which modify the $t\bar{t}Z$ vertex.

5 data tables

The result of the simultaneous fit to the $t\bar{t}Z$ and $t\bar{t}W$ cross sections.

68% confidence level (CL) contours of the measured $t\bar{t}Z$ and $t\bar{t}W$ cross sections.

95% confidence level (CL) contours of the measured $t\bar{t}Z$ and $t\bar{t}W$ cross sections.

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Measurements of the pp$\to$WZ inclusive and differential production cross section and constraints on charged anomalous triple gauge couplings at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 04 (2019) 122, 2019.
Inspire Record 1713417 DOI 10.17182/hepdata.89320

The WZ production cross section is measured in proton-proton collisions at a centre-of-mass energy $\sqrt{s} =$ 13 TeV using data collected with the CMS detector, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The inclusive cross section is measured to be $\sigma_{\text{tot}}$(pp $\to$ WZ$)$ = 48.09 $^{+1.00}_{-0.96}$ (stat) $^{+0.44}_{-0.37}$ (theo) $^{+2.39}_{-2.17}$ (syst) $\pm$ 1.39 (lumi) pb, resulting in a total uncertainty of $-$2.78/$+$2.98 pb. Fiducial cross section and ratios of charge-dependent cross section measurements are provided. Differential cross section measurements are also presented with respect to three variables: the Z boson transverse momentum $p_\mathrm{T}$, the leading jet $p_\mathrm{T}$, and the $m$(WZ) variable, defined as the invariant mass of the system composed of the three leptons and the missing transverse momentum. Differential measurements with respect to the W boson $p_\mathrm{T}$, separated by charge, are also shown. Results are consistent with standard model predictions, favouring next-to-next-to-leading-order predictions over those at next-to-leading order. Constraints on anomalous triple gauge couplings are derived via a binned maximum likelihood fit to the $m$(WZ) variable.

14 data tables

Differential cross section in bins of pT(Z). Values are expressed as a fraction of the total cross section. The eee and eem final states are shown.

Expected and observed one-dimensional confidence intervals (CI) at 95% confidence level for each of the considered EFT parameters, accounting only for the interference term between the SM amplitude and the BSM one. The one-dimensional intervals for each parameter are computed fixing the other two parameters to zero, the SM value.

Expected and observed one-dimensional confidence intervals (CI) at 95% confidence level for each of the considered EFT parameters. Both the square matrix of the dimension-6 contribution and the interference term between the SM amplitude and the BSM one are accounted for. The one-dimensional intervals for each parameter are computed fixing the other two parametes to zero, the SM value.

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Discovery reach for wino and higgsino dark matter with a disappearing track signature at a 100 TeV $pp$ collider

Saito, Masahiko ; Sawada, Ryu ; Terashi, Koji ; et al.
Eur.Phys.J.C 79 (2019) 469, 2019.
Inspire Record 1713045 DOI 10.17182/hepdata.90451

Within the theory of supersymmetry, the lightest neutralino is a dark matter candidate and is often assumed to be the lightest supersymmetric particle (LSP) as well. If the neutral wino or higgsino is dark matter, the upper limit of the LSP mass is determined by the observed relic density of dark matter. If the LSP is a nearly-pure neutral state of the wino or higgsino, the lightest chargino state is expected to have a significant lifetime due to a tiny mass difference between the LSP and the chargino. This article presents discovery potential of the 100 TeV future circular hadron collider (FCC) for the wino and higgsino dark matter using a disappearing-track signature. The search strategy to extend the discovery reach to the thermal limits of wino/higgsino dark matter is discussed with detailed studies on the background rate and the reference design of the FCC-hadron detector under possible running scenarios of the FCC-hadron machine. A proposal of modifying the detector layout and several ideas to improve the sensitivity further are also discussed.

14 data tables

One of three barrel inner-tracker layouts considered in this study; the default layout $\#$1. The contour drawn behind the layouts shows the number of chargino decays in 3 TeV wino signal events with 30 ab$^{-1}$ at a given position. The analysis considers the region $|\eta|<1$, denoted by the dotted lines.

Leading jet $p_{T}$ distributions after removing events containing isolated leptons with 30 ab$^{-1}$ at $\sqrt{s}=100$ TeV. The SM backgrounds from $W/Z$+jets and top production processes are shown as filled histograms. Also shown as dashed (dotted) line is the 3 (1) TeV wino (higgsino) signal scaled up by a factor 1000.

$E_{\text{T}}^{\text{miss}}$ distributions after removing events containing isolated leptons with 30 ab$^{-1}$ at $\sqrt{s}=100$ TeV. The SM backgrounds from $W/Z$+jets and top production processes are shown as filled histograms. Also shown as dashed (dotted) line is the 3 (1) TeV wino (higgsino) signal scaled up by a factor 1000.

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Search for dark matter produced in association with a single top quark or a top quark pair in proton-proton collisions at $ \sqrt{s}=13 $ TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 03 (2019) 141, 2019.
Inspire Record 1712378 DOI 10.17182/hepdata.88882

A search for dark matter produced in association with top quarks in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. The data set used corresponds to an integrated luminosity of 35.9 fb$^{-1}$ recorded with the CMS detector at the LHC. Whereas previous searches for neutral scalar or pseudoscalar mediators considered dark matter production in association with a top quark pair only, this analysis also includes production modes with a single top quark. The results are derived from the combination of multiple selection categories that are defined to target either the single top quark or the top quark pair signature. No significant deviations with respect to the standard model predictions are observed. The results are interpreted in the context of a simplified model in which a scalar or pseudoscalar mediator particle couples to a top quark and subsequently decays into dark matter particles. Scalar and pseudoscalar mediator particles with masses below 290 and 300 GeV, respectively, are excluded at 95 % confidence level, assuming a dark matter particle mass of 1 GeV and mediator couplings to fermions and dark matter particles equal to unity.

24 data tables

Background-only post-fit $p_{T}^{miss}$ distributions for the CRs of the SL selection. The total theory signal (t/t+DM and tt+DM summed together) is negligible and therefore is not shown. The last bin contains overflow events.

Background-only post-fit $p_{T}^{miss}$ distributions for the CRs of the SL selection. The total theory signal (t/t+DM and tt+DM summed together) is negligible and therefore is not shown. The last bin contains overflow events.

Background-only post-fit $p_{T}^{miss}$ distributions for the CRs of the SL selection. The total theory signal (t/t+DM and tt+DM summed together) is negligible and therefore is not shown. The last bin contains overflow events.

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Collision Energy Dependence of $p_{\rm t}$ Correlations in Au+Au Collisions at RHIC

The STAR collaboration Adam, Jaroslav ; Adams, Joseph ; Agakishiev, Geydar ; et al.
Phys.Rev.C 99 (2019) 044918, 2019.
Inspire Record 1712047 DOI 10.17182/hepdata.105509

We present two-particle $p_{\rm t}$ correlations as a function of event centrality for Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV at the Relativistic Heavy Ion Collider using the STAR detector. These results are compared to previous measurements from CERES at the Super Proton Synchrotron and from ALICE at the Large Hadron Collider. The data are compared with UrQMD model calculations and with a model based on a Boltzmann-Langevin approach incorporating effects from thermalization. The relative dynamical correlations for Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV show a power law dependence on the number of participant nucleons and agree with the results for Pb+Pb collisions at $\sqrt{s_{\rm NN}} = 2.76~ {\rm TeV}$ from ALICE. As the collision energy is lowered from $\sqrt{s_{\rm NN}}$ = 200 GeV to 7.7 GeV, the centrality dependence of the relative dynamical correlations departs from the power law behavior observed at the higher collision energies. In central collisions, the relative dynamical correlations increase with collision energy up to $\sqrt{s_{\rm NN}}$ = 200 GeV in contrast to previous measurements that showed little dependence on the collision energy.

57 data tables

'The relative dynamical correlation as a function of $N_{part}$'

'The relative dynamical correlation as a function of $N_{part}$'

'The relative dynamical correlation as a function of $N_{part}$'

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Search for $\tau \to 3\mu$ decays using $\tau$ leptons produced in D and B meson decays

The CMS collaboration
CMS-PAS-BPH-17-004, 2019.
Inspire Record 1726178 DOI 10.17182/hepdata.95113

A search for charged lepton flavor violating decays $\tau\to3\mu$ has been performed using proton-proton collisions with a center-of-mass energy of 13 TeV. The analysis uses the data set collected by the CMS detector in 2016, corresponding to an integrated luminosity of 33 fb$^{-1}$, and exploits $\tau$ leptons produced in D and B meson decays. No signal is observed, and an upper limit of $8.8\times 10^{-8}$ is set at the $90\%$ confidence level on the branching fraction of the $\tau$ lepton to three muons.

1 data table

Expected and observed 90% CL upper limits on the branching fraction of the tau lepton to 3 muons.


Study of the $\mathrm{B}^{+}\rightarrow \mathrm{J}/\psi \bar{\Lambda} \mathrm{p}$ decay in proton-proton collisions at $\sqrt{s}= 8~\mathrm{TeV}$

The CMS collaboration
CMS-PAS-BPH-18-005, 2019.
Inspire Record 1726694 DOI 10.17182/hepdata.89270

A study of the $\mathrm{B}^{+} \rightarrow \mathrm{J}/\psi \bar{\Lambda} \mathrm{p}$ decay is reported, using proton-proton collision data collected at $\sqrt{s}= 8~\mathrm{TeV}$ by the CMS experiment at the LHC, corresponding to an integrated luminosity of $19.6~\mathrm{fb}^{-1}$. The ratio of branching fractions $\frac{{\cal B}(\mathrm{B}^{+} \rightarrow \mathrm{J}/\psi \bar{\Lambda} \mathrm{p})}{{\cal B}(\mathrm{B}^{+} \rightarrow \mathrm{J}/\psi \mathrm{K}^{*+})}$ is measured to be $1.054\pm0.057~\text{(stat)} \pm0.028~\text{(syst)}\pm0.011({\cal B})\%$, where the first uncertainty is statistical, the second is systematic, and the third reflects the uncertainties in the world-average branching fractions. The invariant mass distributions of $\mathrm{J}/\psi \bar{\Lambda}$, $\mathrm{J}/\psi \mathrm{p}$, and $\bar{\Lambda} \mathrm{p}$ systems produced in the $\mathrm{B}^{+} \rightarrow \mathrm{J}/\psi \bar{\Lambda} \mathrm{p}$ decay are investigated and found to be inconsistent with the pure phase space hypothesis. The analysis is extended by using a model-independent angular amplitude analysis, which shows that the inclusion of contributions from excited kaons in the $\bar{\Lambda} \mathrm{p}$ system does improve the description of the observed invariant mass distributions.

1 data table

The measured ratio of branching fractios


Measurement of prompt ${ D_{s}^{+}}$ production in pp and PbPb collisions at $\sqrt{s_{_{\text{NN}}}}$ = 5.02 TeV

The CMS collaboration
CMS-PAS-HIN-18-017, 2019.
Inspire Record 1766111 DOI 10.17182/hepdata.88295

The transverse momentum (pT) spectra of prompt D+ s mesons and charge conjugates are measured in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair using the CMS detector at the LHC. The measurement is performed through the D+ s !fp+ !K+K􀀀p+ decay channels with the D+ s rapidity range jyj < 1.0. The D+ s production in the pT range from 2 (6) GeV/c to 40 GeV/c in pp (PbPb) collisions is measured. Suppression of the D+ s nuclear modification factor (RAA) in PbPb collisions suggests a strong interaction between charm quarks and the quarkgluon plasma. The double ratio of prompt D+ s to prompt D0 production in pp and PbPb is consistent with a PHSD model calculation and consistent with unity, which indicates that strange charm meson enhancement in PbPb collisions is not significant in the measured D+ s pT interval.

5 data tables

$p_T$ differential cross section of $D^+_s$ s in pp and PbPb at 5.02 TeV. The $p_T$-differential cross section of $D^+_s$ in pp collisions and $p_T$-differential corrected yield of $D^+_s$ mesons scaled by T$_\text{AA}$ in PbPb collisions are shown.

The ratio between $p_T$-differential cross section of $D^+_s$ in pp collisions and $p_T$-differential corrected yield of $D^+_s$ mesons scaled by T$_\text{AA}$ in PbPb collisions over PYTHIA8 are shown.

The nuclear modification factor (R$_\text{AA}$) of $D^+_s$.

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