The associated production of Higgs and $W$ bosons via vector-boson fusion (VBF) is highly sensitive to the relative sign of the Higgs boson couplings to $W$ and $Z$ bosons. In this Letter, two searches for this process are presented, using 140 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}$ = 13 TeV recorded by the ATLAS detector at the LHC. The first search targets scenarios with opposite-sign couplings of the $W$ and $Z$ bosons to the Higgs boson, while the second targets Standard Model-like scenarios with same-sign couplings. Both analyses consider Higgs decays into a pair of $b$-quarks and $W$ decays with an electron or muon. The opposite-sign coupling hypothesis is excluded with significance much greater than $5\sigma$, and the observed (expected) upper limit set on the cross-section for VBF $WH$ production is 9.0 (8.7) times the Standard Model value.
Data compared to the background prediction in each region of the negative $\lambda_{WZ}$ analysis, before the fit to data. The signal prediction with $\kappa_{W} = +1$, $\kappa_{Z} = -1$ is shown overlaid. The predicted signal yield with $\kappa_{W} = +1$, $\kappa_{Z} = +1$ in SR$^{-}$ is 2.93 events, which is not shown in the figure. The shaded bands represent the total pre-fit uncertainty on the prediction. The uncertainty does not include the normalization of the main backgrounds, which is unconstrained in the fit.
Data compared to the background prediction in each region of the negative $\lambda_{WZ}$ analysis, after the fit to data. The fitted signal strength is $\hat{\mu} = -0.027$, corresponding to $-8$ events. This contribution is not shown in the figure. The predicted signal yield with $\kappa_{W} = +1$, $\kappa_{Z} = +1$ in SR$^{-}$ is 2.93 events, which is also not shown in the figure. The shaded bands represent the total post-fit uncertainty on the prediction.
Data compared to the SM prediction in each region of the positive \lam{} analysis, before the fit to data. The shaded bands represent the total pre-fit uncertainty on the prediction. The uncertainty does not include the normalization of the main backgrounds, which is unconstrained in the fit.
Partonic collectivity is one of the necessary signatures for the formation of Quark-Gluon-Plasma in high-energy nuclear collisions. Number of Constituent Quarks (NCQ) scaling has been observed for light hadron elliptic flow $v_2$ in top energy nuclear collisions at RHIC and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In this letter, a systematic analysis of $v_2$ of $\pi^{\pm}$, $K^{\pm}$, $K^{0}_{S}$, $p$ and $\Lambda$ in Au+Au collisions at ${\sqrt{s_{_{\rm{NN}}}}}$ = 3.2, 3.5, 3.9, and 4.5 GeV, with the STAR experiment at RHIC, is presented. NCQ scaling is markedly violated at 3.2 GeV, consistent with a hadronic-interaction dominated equation of state. However, as the collision energy increases, a gradual evolution to NCQ scaling is observed. This beam-energy dependence of $v_2$ for all hadrons studied provides evidence for the onset of dominant partonic interactions by ${\sqrt{s_{_{\rm{NN}}}}}$ = 4.5 GeV.
$p_{T}$ dependence of $v_{2}$ for $\pi^{+}$ in Au+Au collisions at 3 GeV
$p_{T}$ dependence of $v_{2}$ for $\pi^{+}$ in Au+Au collisions at 3.2 GeV
$p_{T}$ dependence of $v_{2}$ for $\pi^{+}$ in Au+Au collisions at 3.5 GeV
The multiplicities of positive and negative pions, kaons and unidentified hadrons produced in deep-inelastic scattering are measured in bins of the Bjorken scaling variable $x$, the relative virtual-photon energy $y$ and the fraction of the virtual-photon energy transferred to the final-state hadron $z$. Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam of both electric charges and a liquid hydrogen target. These measurements cover the kinematic domain with photon virtuality $Q^2 > 1$ (GeV/$c)^2$, $0.004 < x < 0.4$, $0.1 < y < 0.7$ and $0.2 < z < 0.85$, in accordance with the kinematic domain used in earlier published COMPASS multiplicity measurements with an isoscalar target. The calculation of radiative corrections was improved by using the Monte Carlo generator DJANGOH, which results in up to 12% larger corrections in the low-$x$ region.
h+/h- multiplicities in (x, y, z) bins with corrections, applied corrections for VM and RC are provided in the table
pi+/pi- multiplicities in (x, y, z) bins with corrections, applied corrections for VM and RC are provided in the table
K+/K- multiplicities in (x, y, z) bins with corrections, applied corrections for VM and RC are provided in the table
The results of a search for the production of two scalar bosons in final states with two photons and two tau leptons are presented. The search considers both nonresonant production of a Higgs boson pair, HH, and resonant production via a new boson X which decays either to HH or to H and a new scalar Y. The analysis uses up to 138 fb$^{-1}$ of proton-proton collision data, recorded between 2016 and 2018 by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV. No evidence for signal is found in the data. For the nonresonant production, the observed (expected) upper limit at 95% confidence level (CL) on the HH production cross section is set at 930 (740) fb, corresponding to 33 (26) times the standard model prediction. At 95% CL, HH production is observed (expected) to be excluded for values of $κ_λ$ outside the range between $-$12 ($-$9.4) and 17 (15). Observed (expected) upper limits at 95% CL for the XHH cross section are found to be within 160 to 2200 (200 to 1800) fb, depending on the mass of X. In the X $\to$ Y($γγ$)H($ττ$) search, the observed (expected) upper limits on the product of the production cross section and decay branching fractions vary between 0.059$-$1.2 fb (0.087$-$0.68 fb). For the X $\to$ Y($γγ$)H($ττ$) search the observed (expected) upper limits on the product of the production cross section and Y $to$ $γγ$ branching fraction vary between 0.69$-$15 fb (0.73$-$8.3 fb) in the low Y mass search, tightening constraints on the next-to-minimal supersymmetric standard model, and between 0.64$-$10 fb (0.70$-$7.6 fb) in the high Y mass search.
Observed and expected 95% CL upper limits on the nonresonant $\mathrm{HH}$ production cross section, $\sigma(\mathrm{pp} \to \mathrm{HH})$, as a function of the Higgs boson self-coupling strength modifier $\kappa_\lambda$. All Higgs boson couplings other than $\lambda$ are assumed to have the values predicted in the SM.
Observed and expected 95% CL upper limits on the nonresonant $\mathrm{HH}$ production cross section, $\sigma(\mathrm{pp} \to \mathrm{HH})$, for thirteen different BSM benchmark scenarios from [arXiv:1507.02245, arXiv:1806.05162] which consider different values of the couplings, $\kappa_\lambda$, $\kappa_t$, $c_{2g}$, $c_g$, and $c_2$ (defined in Table 1).
Observed and expected 95% CL upper limits on the cross section for the resonant production of a new spin-0 particle $\mathrm{X}^{(0)}$ which decays to Higgs boson pairs, $\sigma(\mathrm{pp} \to \mathrm{X}^{(0)} \to \mathrm{HH})$, given for different values of $m_\mathrm{X}$ in the range 260-1000 GeV.
This paper presents a measurement of the production cross-section of a $Z$ boson in association with $b$- or $c$-jets, in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 140 fb$^{-1}$. Inclusive and differential cross-sections are measured for events containing a $Z$ boson decaying into electrons or muons and produced in association with at least one $b$-jet, at least one $c$-jet, or at least two $b$-jets with transverse momentum $p_\textrm{T} > 20$ GeV and rapidity $|y| < 2.5$. Predictions from several Monte Carlo generators based on next-to-leading-order matrix elements interfaced with a parton-shower simulation, with different choices of flavour schemes for initial-state partons, are compared with the measured cross-sections. The results are also compared with novel predictions, based on infrared and collinear safe jet flavour dressing algorithms. Selected $Z + \ge 1 c$-jet observables, optimized for sensitivity to intrinsic-charm, are compared with benchmark models with different intrinsic-charm fractions.
Figure 6(left) of the article. Measured fiducial cross sections for events with $Z \left( \rightarrow \ell \ell \right) \geq 1 b$-jet. The thin inner band corresponds to the statistical uncertainty of the data, and the outer band to statistical and systematic uncertainties of the data, added in quadrature.
Figure 6(right) of the article. Measured fiducial cross sections for events with $Z \left( \rightarrow \ell \ell \right) \geq 2 b$-jets. The thin inner band corresponds to the statistical uncertainty of the data, and the outer band to statistical and systematic uncertainties of the data, added in quadrature.
Figure 7 of the article. Measured fiducial cross sections for events with $Z \left( \rightarrow \ell \ell \right) \geq 1 c$-jet. The thin inner band corresponds to the statistical uncertainty of the data, and the outer band to statistical and systematic uncertainties of the data, added in quadrature.
Correlations between event-by-event fluctuations of anisotropic flow harmonics are measured in Pb-Pb collisions at a center-of-mass energy per nucleon pair of 5.02 TeV, as recorded by the ALICE detector at the LHC. This study presents correlations up to the hexagonal flow harmonic, $v_6$, which was measured for the first time. The magnitudes of these higher-order correlations are found to vary as a function of collision centrality and harmonic order. These measurements are compared to viscous hydrodynamic model calculations with EKRT initial conditions and to the iEBE-VISHNU model with TRENTo initial conditions. The observed discrepancies between the data and the model calculations vary depending on the harmonic combinations. Due to the sensitivity of model parameters estimated with Bayesian analyses to these higher-order observables, the results presented in this work provide new and independent constraints on the initial conditions and transport properties in theoretical models used to describe the system created in heavy-ion collisions.
NSC(5,2) vs centrality in Pb-Pb collisions at 5.02 TeV
NSC(5,3) vs centrality in Pb-Pb collisions at 5.02 TeV
NSC(6,2) vs centrality in Pb-Pb collisions at 5.02 TeV
The distribution of angular correlations between prompt charm hadrons and primary charged particles in pp collisions is sensitive to the charm-quark hadronisation process. In this letter, charm-baryon correlations are measured for the first time by studying the azimuthal-angle difference between charged particles and prompt $\Lambda_{\rm c}^+$ baryons produced in pp collisions at a centre-of-mass energy $\sqrt{s} = 13$ TeV, with the ALICE detector. $\Lambda_{\rm c}^+$ baryons are reconstructed at midrapidity ($|y| < 0.5$) in the transverse-momentum interval $3 < p_{\rm T} < 16$ GeV/$c$, and correlated with charged particles with $p_{\rm T} > 0.3$ GeV/$c$ and pseudorapidity $|\eta| < 0.8$. For $3 < p_{\rm T}^{\Lambda_{\rm c}^+,{\rm D}} < 5$ GeV/$c$, the comparison with published measurements of D-meson and charged-particle correlations in the same collision system hints at a larger number of low-momentum particles associated with $\Lambda_{\rm c}^+$-baryon triggers than with D-meson triggers, both in the collinear and opposite directions with respect to the trigger particle. These differences can be quantified by the comparison of the properties of the near- and away-side correlation peaks, and are not reproduced by predictions of various Monte Carlo event generators, generally underpredicting the associated particle yields at $p_{\rm T}^{\rm assoc} < 1$ GeV/$c$. This tension between $\Lambda_{\rm c}^+$-baryon and D-meson associated peak yields could suggest a modified fragmentation of the charm quark, or a different hadronisation process, when a charm baryon is produced in the final state.
Azimuthal-correlation distributions of $\Lambda_\mathrm{c}^{+}$ baryons with associated particles in pp collisions at $\sqrt{s} = 13$ TeV, compared to the average of the azimuthal-correlation distributions of D$^{0}$, D$^{+}$, and D$^{*+}$ mesons with associated particles in the same collision system. The distributions are shown after the baseline subtraction. Charm hadrons are reported for $3 < p_{\rm T} < 5$ GeV/$c$, associated particles for $0.3 < p_{\rm T} < 1$ GeV/$c$. The rapidity range for the D mesons and $\Lambda_\mathrm{c}^{+}$ baryons is $|y^{\rm D,\Lambda_\mathrm{c}^{+}}| < 0.5$. Correlations are integrated for $|\Delta\eta|=|\eta_{\rm ch}-\eta_{\rm D,\Lambda_{c}^{+}}| < 1$. The azimuthal-correlation distributions are reported in the range $0 < \Delta\varphi < \pi$.
Azimuthal-correlation distributions of $\Lambda_\mathrm{c}^{+}$ baryons with associated particles, i.e. primary charged particles, in pp collisions at $\sqrt{s} = 13$ TeV, compared to the average of the azimuthal-correlation distributions of D$^{0}$, D$^{+}$, and D$^{*+}$ mesons with associated particles in the same collision system. The distributions are shown after the baseline subtraction. Charm hadrons are reported for $5 < p_{\rm T} < 8$ GeV/$c$, associated particles for $0.3 < p_{\rm T} < 1$ GeV/$c$. The rapidity range for the D mesons and $\Lambda_\mathrm{c}^{+}$ baryons is $|y^{\rm D,\Lambda_\mathrm{c}^{+}}| < 0.5$. Correlations are integrated for $|\Delta\eta|=|\eta_{\rm ch}-\eta_{\rm D,\Lambda_{c}^{+}}| < 1$. The azimuthal-correlation distributions are reported in the range $0 < \Delta\varphi < \pi$.
Azimuthal-correlation distributions of $\Lambda_\mathrm{c}^{+}$ baryons with associated particles, i.e. primary charged particles, in pp collisions at $\sqrt{s} = 13$ TeV, compared to the average of the azimuthal-correlation distributions of D$^{0}$, D$^{+}$, and D$^{*+}$ mesons with associated particles in the same collision system. The distributions are shown after the baseline subtraction. Charm hadrons are reported for $8 < p_{\rm T} < 16$ GeV/$c$, associated particles for $p_{\rm T} > 1$ GeV/$c$. The rapidity range for the D mesons and $\Lambda_\mathrm{c}^{+}$ baryons is $|y^{\rm D,\Lambda_\mathrm{c}^{+}}| < 0.5$. Correlations are integrated for $|\Delta\eta|=|\eta_{\rm ch}-\eta_{\rm D,\Lambda_{c}^{+}}| < 1$. The azimuthal-correlation distributions are reported in the range $0 < \Delta\varphi < \pi$.
The cross section of the process e+e−→π+π−π0 has been measured in the c.m. energy range 984–1060 MeV with the CMD-2 detector at the VEPP-2M collider. The obtained value of Br(ϕ→e+e−)Br(ϕ→π+π−π0)=(4.51±0.16±0.11)×10−5 is in good agreement with the previous measurements and has the best accuracy. Analysis of the Dalitz plot was performed. The contributions of the dominant ϕ→ρπ mechanism as well as of a small direct ϕ→3π amplitude were determined.
The Born cross section of the process e+e- -> pi+pi-pi0. The ranges of the c.m.s. energies are [2E-2*sigma, 2E+2*sigma], where sigma is statistical uncertainty of the VEPP-2M collider beam energy. The 2.5% systematic uncertainty of the cross section is fully correlated across the c.m.s. energy points.
None
Fitted peak cross section. The ISR radiative correction was included in the fitted resonance formula, while the measured cross section data vs energy as shown on Figure 1 are without radiative correction.
Visible cross section. The ISR radiative correction wasn't applied for these points and was included in definition of the fitted function to extract the peak value.
None
Fitted peak cross section.
The cross section of the process e+e- -> pi+pi-pi0. The value of fitted peak cross section was additionaly corrected by 3.5% for the nuclear interaction loss and 1.2% for Br(pi0->e+e-gamma)
On the electron-positron storage ring VEPP-2M using the Cryogenic Magnetic Detector, the cross section of the e+e- -> π+π-π0 process was measured in the energy range 2x420-2x510 MeV. The energy dependence of the cross section is consistent with the predictions of the vector dominance model taking into account the interference of omega and phi mesons. The optimal value of the omega-phi interference phase is 136+-36+-10 degree.
The Born cross section of the process e+e- -> pi+pi-pi0.
The cross section for the e$^{+}$ e$^{–}$ → π$^{+}$π$^{–}$π$^{0}$ process in the energy range 1.05–2.00 GeV has been measured using the data collected in the experiment with the Spherical Neutral Detector (SND) at the VEPP-2000 e$^{+}$ e$^{–}$ collider. The obtained results on the cross section are in good agreement with previous measurements by the SND at the VEPP-2M collider and BABAR, but have a better accuracy.
The Born cross section of the process e+e- -> pi+pi-pi0.
The dynamics of the process $ e^+e^- \to \pi^+\pi^-\pi^0 $ is studied in the energy region from 1.15 to 2.00 GeV using data accumulated with the SND detector at the VEPP-2000 $e^+e^-$ collider. The Dalitz plot distribution and $\pi^+\pi^-$ mass spectrum are analyzed in a model including the intermediate states $\rho(770)\pi$, $\rho(1450)\pi$, and $\omega\pi^0$. As a result, the energy dependences of the $\rho(770)\pi$ and $\rho(1450)\pi$ cross sections and the relative phases between the $\rho(770)\pi$ amplitude and the $\rho(1450)\pi $ and $\omega\pi^0$ amplitudes are obtained. The $\rho(1450)\pi$ cross section has a peak in the energy region of the $\omega(1650)$ resonance (1.55-1.75 GeV). In this energy range the contributions of the $\rho(770)\pi$ and $\rho(1450)\pi$ states are of the same order of magnitude. No resonance structure near 1.65 GeV is observed in the $\rho(770)\pi$ cross section. We conclude that the intermediate state $\rho(1450)\pi$ gives a significant contribution to the decay of $\omega (1650)\to\pi^+\pi^-\pi^0$, whereas the $\rho(770)\pi$ mechanism dominates in the decay $\omega(1420)\to\pi^+\pi^-\pi^0$.
The Born cross section of the process e+e- -> pi+pi-pi0, scan 2012.
The Born cross section of the process e+e- -> pi+pi-pi0, scan 2011.
The cross section of intermediate states rho pi0, rho' pi0, omega pi0 in the process e+e- -> pi+pi-pi0 extracted by the Dalitz plot analysis.
We report the first measurement of the azimuthal anisotropy of J$/\psi$ at forward rapidity ($1.2<|\eta|<2.2$) in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV at the Relativistic Heavy Ion Collider. The data were collected by the PHENIX experiment in 2014 and 2016 with integrated luminosity of 14.5~nb$^{-1}$. The second Fourier coefficient ($v_2$) of the azimuthal distribution of $J/\psi$ is determined as a function of the transverse momentum ($p_T$) using the event-plane method. The measurements were performed for several selections of collision centrality: 0%--50%, 10%--60%, and 10%-40%. We find that in all cases the values of $v_2(p_T)$, which quantify the elliptic flow of J$/\psi$, are consistent with zero. The results are consistent with measurements at midrapidity, indicating no significant elliptic flow of the J$/\psi$ within the quark-gluon-plasma medium at collision energies of $\sqrt{s_{_{NN}}}=200$ GeV.
JPSI v2 in Au+Au collisions as a function of pT (GeV/c) for 10%--60% centrality with pT binned by [0, 1], [1, 2], [2, 3], and [3, 5] GeV/c.
JPSI v2 in Au+Au collisions as a function of pT (GeV/c) for 10%--60% centrality with pT binned by [0, 0.5], [0.5, 1], [1, 5], and [0, 5] GeV/c.
JPSI v2 in Au+Au collisions as a function of pT (GeV/c) for 10%--40% centrality with pT binned by [0, 2], [2, 5], and [5, 10] GeV/c.
A first search is presented for vector-like leptons (VLLs) decaying into a light long-lived pseudoscalar boson and a standard model $\tau$ lepton. The pseudoscalar boson is assumed to have a mass of 2 GeV and to decay exclusively into a pair of photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016-2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying $\tau$ lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.
The cluster reconstruction efficiency, including both DT and CSC clusters, as a function of the simulated r and |z| decay positions of the pseudoscalar into photons in events with MET > 200 GeV, for a VLL mass of 700 GeV and a pseudoscalar mass of 2 GeV, and a range of ctau values uniformly distributed between 0.01 and 0.1 m.
Distributions of the number of hits in the cluster (Nhits) for the DT category in the signal region (SR). The last histogram bin contains all overflow events.
Distributions of the number of hits in the cluster (Nhits) for the CSC category in the signal region (SR). The last histogram bin contains all overflow events.
We report on the measurement of the size of the particle-emitting source from two-baryon correlations with ALICE in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV. The source radius is studied with low relative momentum p-p, $\bar{\rm{p}}$-$\bar{\rm{p}}$, p-$Λ$ and $\bar{\rm{p}}$-$\barΛ$ pairs as a function of the pair transverse mass $m_{\rm{T}}$ considering for the first time in a quantitative way the effect of strong resonance decays. After correcting for this effect, the radii extracted for pairs of different particle species agree. This indicates that protons, antiprotons, $Λ$, and $\barΛ$ originate from the same source. Within the measured $m_{\rm{T}}$ range (1.1-2.2) GeV/$c^{2}$ the invariant radius of this common source varies between 0.85 and 1.3 fm. These results provide a precise reference for studies of the strong hadron-hadron interactions and for the investigation of collective properties in small colliding systems.
Source radius $r_{0}$ as a function of〈$m_{T}$〉for the assumption of a purely Gaussian source. The blue crosses result from fitting the p–p correlation function with the strong Argonne v18 potential. The green squared crosses (red triangular crosses) result from fitting the p–Λ correlation functions with the strong χEFT LO (NLO) potential. Statistical (lines) and systematic (boxes) uncertainties are shown separately.
Source radius $r_0$ as a function of〈$m_\mathrm{T}$〉for the assumption of a purely Gaussian source. The blue crosses result from fitting the p–p correlation function with the strong Argonne v18 potential. The green squared crosses (red triangular crosses) result from fitting the p–Λ correlation functions with the strong χEFT LO (NLO) potential. Statistical (lines) and systematic (boxes) uncertainties are shown separately.
Source radius $r_{0}$ as a function of〈$m_{T}$〉for the assumption of a purely Gaussian source. The blue crosses result from fitting the p–p correlation function with the strong Argonne v18 potential. The green squared crosses (red triangular crosses) result from fitting the p–Λ correlation functions with the strong χEFT LO (NLO) potential. Statistical (lines) and systematic (boxes) uncertainties are shown separately.
In this letter, we present the first measurement of direct photons at the transverse momentum of $ 1 < p_{\rm T} < 6$ GeV/$c$ at midrapidity $|η| < 0.8$ in inelastic and high-multiplicity proton--proton collisions at a centre-of-mass energy of $\sqrt{s} =$ 13 TeV. The fraction of virtual direct photons in the inclusive virtual photon spectrum is obtained from a fit to the dielectron invariant mass spectrum. In the limit of zero invariant mass, this fraction is equal to the relative contribution of real direct photons in the inclusive real photon spectrum. Contributions from decays of light-flavour neutral mesons are estimated using independent measurements in proton-proton collisions at the same energy and the same event class. For the first time at the LHC energies, a direct-photon signal is observed at low $p_{\rm T}$ in both inelastic and high-multiplicity event classes, with a significance of 3.2$σ$ and 1.9$σ$ in terms of standard deviations, correspondingly. The yield of direct photons in inelastic pp collisions is compared to perturbative QCD calculations. The integrated photon yield is studied as a function of charged-particle multiplicity and is compared to the results from other experiments and theoretical calculations. The results show a significant increase of direct-photon yield with charged-particle multiplicity.
The dielectron cross section in inelastic pp collisions at $\sqrt{s}$ = 13 TeV as a function of invariant mass for 2 < $p_{\rm T,ee}$ < 3 GeV/$c$.
The dielectron cross section in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV as a function of invariant mass for 2 < $p_{\rm T,ee}$ < 3 GeV/$c$.
The direct-photon fraction r in inelastic pp collisions at $\sqrt{s}$ = 13 TeV as a function of transverse momentum for 1 < $p_{\rm T}$ < 6 GeV/$c$. r is the ratio of direct GAMMA to inclusive GAMMA.
The $p_{\rm T}$-differential cross sections of prompt charm-strange baryons $\Xi^0_{\rm c}$ and $\Xi^+_{\rm c}$ were measured at midrapidity ($|y| < 0.5$) in proton$-$proton (pp) collisions at a centre-of-mass energy $\sqrt{s}=13$ TeV with the ALICE detector at the LHC. The $\Xi^0_{\rm c}$ baryon was reconstructed via both the semileptonic decay ($\Xi^{-}{\rm e^{+}}\nu_{\rm e}$) and the hadronic decay ($\Xi^{-}{\rm \pi^{+}}$) channels. The $\Xi^+_{\rm c}$ baryon was reconstructed via the hadronic decay ($\Xi^{-}\pi^{+}\pi^{+}$) channel. The branching-fraction ratio $\rm {\rm BR}(\Xi_c^0\rightarrow \Xi^-e^+\nu_e)/\rm {\rm BR}(\Xi_c^0\rightarrow \Xi^{-}\pi^+)=$ 1.38 $\pm$ 0.14 (stat) $\pm$ 0.22 (syst) was measured with a total uncertainty reduced by a factor of about 3 with respect to the current world average reported by the Particle Data Group. The transverse momentum ($p_{\rm T}$) dependence of the $\Xi^0_{\rm c}$- and $\Xi^+_{\rm c}$-baryon production relative to the ${\rm D^0}$-meson and to the $\Sigma^{0,+,++}_{\rm c}$- and $\Lambda^+_{\rm c}$-baryon production are reported. The baryon-to-meson ratio increases towards low $p_{\rm T}$ up to a value of approximately 0.3. The measurements are compared with various models that take different hadronisation mechanisms into consideration. The results provide stringent constraints to these theoretical calculations and additional evidence that different processes are involved in charm hadronisation in electron$-$positron ($\rm e^+e^-$) and hadronic collisions.
Cross section of prompt $\rm \Xi_c^0$ baryon as a function of $p_{\rm T}$ in pp collisions at $\sqrt{s}=13$ TeV for $|y|<0.5$.
Cross section of prompt $\rm \Xi_c^+$ baryon as a function of $p_{\rm T}$ in pp collisions at $\sqrt{s}=13$ TeV for $|y|<0.5$.
$\rm \Xi_c^0/D^0$ ratio as a function of $p_{\rm T}$ in pp collisions at $\sqrt{s}=13$ TeV for $|y|<0.5$.
This paper presents a study of the inclusive forward J/$\psi$ yield as a function of forward charged-particle multiplicity in pp collisions at $\sqrt{s} = 13$ TeV using data collected by the ALICE experiment at the CERN LHC. The results are presented in terms of relative J/$\psi$ yields and relative charged-particle multiplicities with respect to these quantities obtained in inelastic collisions having at least one charged particle in the pseudorapidity range $|\eta| < 1$. The J/$\psi$ mesons are reconstructed via their decay into $\mu^+ \mu^-$ pairs in the forward rapidity region ($2.5 < y < 4$). The relative multiplicity is estimated in the forward pseudorapidity range $-3.7 < \eta < -1.7$, which overlaps with the J/$\psi$ rapidity region. The results show a steeper-than-linear increase of the J/$\psi$ yields versus the multiplicity. They are compared with previous measurements and theoretical model calculations.
Forward inclusive J/$\psi$ relative yield as a function of the relative multiplicity in −3.7 < $\eta$ < −1.7 in INEL > 0 pp collisions at $\sqrt{s}$ = 13 TeV.
High-momentum two-particle correlations are a useful tool for studying jet-quenching effects in the quark-gluon plasma. Angular correlations between neutral-pion triggers and charged hadrons with transverse momenta in the range 4--12~GeV/$c$ and 0.5--7~GeV/$c$, respectively, have been measured by the PHENIX experiment in 2014 for Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV. Suppression is observed in the yield of high-momentum jet fragments opposite the trigger particle, which indicates jet suppression stemming from in-medium partonic energy loss, while enhancement is observed for low-momentum particles. The ratio and differences between the yield in Au$+$Au collisions and $p$$+$$p$ collisions, $I_{AA}$ and $\Delta_{AA}$, as a function of the trigger-hadron azimuthal separation, $\Delta\phi$, are measured for the first time at the Relativistic Heavy Ion Collider. These results better quantify how the yield of low-$p_T$ associated hadrons is enhanced at wide angle, which is crucial for studying energy loss as well as medium-response effects.
Per-trigger jet-pair yield as a function of $\Delta\phi$ for selected $\pi^0$ trigger and charged-hadron-associated $p_T$ combinations (${{p_{T,\pi^0}} \otimes p_{T,h}}$) in Au$+$Au collisions. Systematic uncertainties for background subtraction and global scale uncertainties are given.
Integrated away-side $I_{AA}$ as a function of $p_T^h$. Systematic uncertainties for background subtraction and global scale uncertainties are given.
Differential away-side a function of Deltaphi 0%-20% collisions. Systematic uncertainties for background subtraction and global scale uncertainties are given.
A measurement is presented of the cross section in proton-proton collisions for the production of two W bosons and one Z boson. It is based on data recorded by the CMS experiment at the CERN LHC at center-of-mass energies $\sqrt{s}$ = 13 and 13.6 TeV, corresponding to an integrated luminosity of 200 fb$^{-1}$. Events with four charged leptons (electrons or muons) in the final state are selected. Both nonresonant WWZ production and ZH production, with the Higgs boson decaying into two W bosons, are reported. For the first time, the two processes are measured separately in a simultaneous fit. Combining the two modes, signal strengths relative to the standard model (SM) predictions of 0.75$^{+0.34}_{-0.29}$ and 1.74$^{+0.71}_{-0.60}$ are measured for $\sqrt{s}$ = 13 and 13.6 TeV, respectively. The observed (expected) significance for the triboson signal is 3.8 (2.5) standard deviations for $\sqrt{s}$ = 13.6 TeV, thus providing the first evidence for triboson production at this center-of-mass energy. Combining the two modes and the two center-of-mass energies, the inclusive signal strength relative to the SM prediction is measured to be 1.03$^{+0.31}_{-0.28}$, with an observed (expected) significance of 4.5 (5.0) standard deviations.
Two-dimensional likelihood scan as a function of the individual WWZ and ZH signal strength parameters for the combined Run 2 and Run 3 datasets
One-dimensional likelihood scan as a function of the inclusive (WWZ + ZH) signal strength parameter for the combined Run 2 and Run 3 datasets
Comparison of the observed number of events to the SM-predicted number of events for each of the bins included in the fit for Run 2 (upper row) and Run 3 (lower row). The SM expectations are shown before performing the fit. The horizontal axis legend also indicates "WWZ-like" and "ZH-like" bins defined based on whether the WWZ BDT score is higher or lower than the ZH score.
A measurement of event-shape variables is presented, using a data sample produced in a special run with approximately one inelastic proton-proton collision per bunch crossing. The data were collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 64 $\mu$b$^{-1}$. A number of observables related to the overall distribution of charged particles in the collisions are corrected for detector effects and compared with simulations. Inclusive event-shape distributions, as well as differential distributions of event shapes as functions of charged-particle multiplicity, are studied. None of the models investigated is able to satisfactorily describe the data. Moreover, there are significant features common amongst all generator setups studied, particularly showing data being more isotropic than any of the simulations. Multidimensional unfolded distributions are provided, along with their correlations.
The unfolded charged particle multiplicity distribution of inelastic proton-proton collisions with at least three charged particles with transverse momentum higher than 0.5 GeV and pseudorapidity between -2.4 and 2.4. The total area of the histogram is normalised to 1.
The unfolded charged particle invariant mass distribution of inelastic proton-proton collisions with at least three charged particles with transverse momentum higher than 0.5 GeV and pseudorapidity between -2.4 and 2.4. The total area of the histogram is normalised to 1.
The unfolded charged particle sphericity distribution of inelastic proton-proton collisions with at least three charged particles with transverse momentum higher than 0.5 GeV and pseudorapidity between -2.4 and 2.4. The total area of the histogram is normalised to 1.
The forward-backward asymmetry in Drell-Yan production and the effective leptonic electroweak mixing angle are measured in proton-proton collisions at $\sqrt{s}$ = 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 138 fb$^{-1}$. The measurement uses both dimuon and dielectron events, and is performed as a function of the dilepton mass and rapidity. The unfolded angular coefficient $A_4$ is also extracted, as a function of the dilepton mass and rapidity. Using the CT18Z set of parton distribution functions, we obtain $\sin\theta^\ell_\text{eff}$ = 0.23152 $\pm$ 0.00031, where the uncertainty includes the experimental and theoretical contributions. The measured value agrees with the standard model fit result to global experimental data. This is the most precise $\sin\theta^\ell_\text{eff}$ measurement at a hadron collider, with a precision comparable to the results obtained at LEP and SLD.
Measured $A_4(|Y|,M))$ distribution for the combined Run 2 data.
Correlation coefficients for the $A_4(|Y|,M)$ values among different $|Y|-M$ bins. The $A_4(|Y|,M)$ values and total uncertainties are shown in Figure 8 in the paper.
The STAR Collaboration presents measurements of the semi-inclusive distribution of charged-particle jets recoiling from energetic direct-photon ($\gamma_{\rm dir}$) and neutral-pion ($\pi^{0}$) triggers in p+p and central Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ GeV over a broad kinematic range, for jet resolution parameters $R$=0.2 and 0.5. Medium-induced jet yield suppression is observed to be larger for $R$=0.2 than for 0.5, reflecting the angular range of jet energy redistribution due to quenching. The predictions of model calculations incorporating jet quenching are not fully consistent with the observations. These results provide new insight into the physical origins of jet quenching.
I_{AA} of Au+Au 0%-15% collisions at sqrt{s_{NN}} = 200 GeV for R = 0.2 of gamma_{dir}+jet with E_{T,trig}= 15-20 GeV.
I_{AA} of Au+Au 0%-15% collisions at sqrt{s_{NN}} = 200 GeV for R = 0.5 of gamma_{dir}+jet with E_{T,trig}= 15-20 GeV.
I_{AA} of Au+Au 0%-15% collisions at sqrt{s_{NN}} = 200 GeV for R = 0.2 of pi^{0}+jet with E_{T,trig}= 11-15 GeV.
Inclusive and differential cross sections for Higgs boson production in proton-proton collisions at a centre-of-mass energy of 13.6 TeV are measured using data collected with the CMS detector at the LHC in 2022, corresponding to an integrated luminosity of 34.7 fb$^{-1}$. Events with the diphoton final state are selected, and the measured inclusive fiducial cross section is $\sigma_\text{fid}$ = 74 $\pm$ 11 (stat) $^{+5}_{-4}$ (syst) fb, in agreement with the standard model prediction of 67.8 $\pm$ 3.8 fb. Differential cross sections are measured as functions of several observables: the Higgs boson transverse momentum and rapidity, the number of associated jets, and the transverse momentum of the leading jet in the event. Within the uncertainties, the differential cross sections agree with the standard model predictions.
Differential fiducial cross sections for pT of the Higgs boson
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Differential fiducial cross sections for rapidity of the Higgs boson
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