The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies ${\sim}0.8$ GeV. The differential measurements are presented as a function of muon and pion kinematics, in the restricted phase-space defined by $p_{\pi^+}>200$MeV/c, $p_{\mu^-}>200$MeV/c, $\cos \theta_{\pi^+}>0.3$ and $\cos \theta_{\mu^-}>0.3$. The total flux integrated $\nu_\mu$ charged current single positive pion production cross section on water in the restricted phase-space is measured to be $\langle\sigma\rangle_\phi=4.25\pm0.48 (\mathrm{stat})\pm1.56 (\mathrm{syst})\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$. The total cross section is consistent with the NEUT prediction ($5.03\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$) and 2$\sigma$ lower than the GENIE prediction ($7.68\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but over-estimates the overall cross section normalization.
Total $\nu_\mu$ CC1$\pi^+$ cross section on water in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$. The T2K data point is placed at the $\nu_\mu$ flux mean energy.
Unfolded $\nu_\mu$ CC1$\pi^+$ differential cross section as a function of $p_\pi$ in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$.
Unfolded $\nu_\mu$ CC1$\pi^+$ differential cross section as a function of $\cos\theta_\pi$ in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$.
T2K reports its first measurements of the parameters governing the disappearance of $\bar{\nu}_\mu$ in an off-axis beam due to flavor change induced by neutrino oscillations. The quasimonochromatic $\bar{\nu}_\mu$ beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the $\bar{\nu}_\mu$ survival probability is expected to be minimal. Using a dataset corresponding to $4.01 \times 10^{20}$ protons on target, $34$ fully contained $\mu$-like events were observed. The best-fit oscillation parameters are $\sin^2 (\bar{\theta}_{23}) = 0.45$ and $|\Delta\bar{m}^2_{32}| = 2.51 \times 10^{-3}$ eV$^2$ with 68% confidence intervals of 0.38 - 0.64 and 2.26 - 2.80 $\times 10^{-3}$ eV$^2$ respectively. These results are in agreement with existing antineutrino parameter measurements and also with the $\nu_\mu$ disappearance parameters measured by T2K.
1$\sigma$ C.L. contour in $\sin^{2}\bar{\theta}_{23}$-$\Delta\bar{m}^{2}_{32}$ plane (normal hierarchy).
90% C.L. contour in $\sin^{2}\bar{\theta}_{23}$-$\Delta\bar{m}^{2}_{32}$ plane (normal hierarchy).
Best-fit point in $\sin^{2}\bar{\theta}_{23}$-$\Delta\bar{m}^{2}_{32}$ plane (normal hierarchy).
A search for new long-lived particles decaying to leptons is presented using proton-proton collisions produced by the LHC at sqrt(s) = 8 TeV. Data used for the analysis were collected by the CMS detector and correspond to an integrated luminosity of 19.7 inverse femtobarns. Events are selected with an electron and a muon that have transverse impact parameter values between 0.02 cm and 2 cm. The search has been designed to be sensitive to a wide range of models with nonprompt e-mu final states. Limits are set on the "displaced supersymmetry" model, with pair production of top squarks decaying into an e-mu final state via R-parity-violating interactions. The results are the most restrictive to date on this model, with the most stringent limit being obtained for a top squark lifetime corresponding to c tau = 2 cm, excluding masses below 790 GeV at 95% confidence level.
Numbers of expected and observed events in the three search regions (see the text for the definitions of these regions). Background and signal expectations are quoted as $N_{\text{exp}} \pm 1\sigma$ stat $\pm 1\sigma$ syst. If the estimated background is zero in a particular search region, the estimate is instead taken from the preceding region. Since this should always overestimate the background, we denote this by a preceding "<".
Expected and observed 95% CL cross section exclusion contours for top squark pair production in the plane of top squark lifetime ($c\tau$) and top squark mass. These limits assume a branching fraction of 100\% through the RPV vertex $\tilde{t}$ $\to$ b l, where the branching fraction to any lepton flavor is equal to 1/3. As indicated in the plot, the region to the left of the contours is excluded by this search.
Electron reconstruction efficiency as function of its tranverse impact parameter, $d_0$.
We have studied the production of charged D ∗ mesons in e + e − annihilation at an average center-of-mass energy of 58.0 GeV. Charged D ∗ mesons were identified using two independent methods; the mass-difference method and the detection of the low transverse-momentum pion. The forward-backward asymmetry of the charm quark production was measured to be A c = −0.61±0.13(stat.)±0.08(syst.). The cross section of inclusive D ∗ production was found to be σ(e + e − →D ∗ ± +X) = 24.5 ± 5.3 ( stat. )±3.0( syst. ) pb. If we assume the standard model prediction for the charm quark production, we obtain the branching ratio for the charm quark to produce a charged D ∗ meson to be Br (c→D ∗+ + X) = (22±5( stat. )±3( syst. ))% .
No description provided.
In July 2012, the ATLAS and CMS Collaborations at the CERN Large Hadron Collider announced the observation of a Higgs boson at a mass of around 125 GeV. Ten years later, and with the data corresponding to the production of 30 times larger number of Higgs bosons, we have learnt much more about the properties of the Higgs boson. The CMS experiment has observed the Higgs boson in numerous fermionic and bosonic decay channels, established its spin-parity quantum numbers, determined its mass and measured its production cross sections in various modes. Here the CMS Collaboration reports the most up-to-date combination of results on the properties of the Higgs boson, including the most stringent limit on the cross section for the production of a pair of Higgs bosons, on the basis of data from proton-proton collisions at a centre-of-mass energy of 13 TeV. Within the uncertainties, all these observations are compatible with the predictions of the standard model of elementary particle physics. Much evidence points to the fact that the standard model is a low-energy approximation of a more comprehensive theory. Several of the standard model issues originate in the sector of Higgs boson physics. An order of magnitude larger number of Higgs bosons, expected to be examined over the next fifteen years, will help deepen our understanding of this crucial sector.
Signal strength modifiers per production mode $\mu_i$.
Signal strength modifiers per decay mode $\mu^f$.
Simultaneous coupling measurement $\kappa_V/\kappa_f$
A search for Higgs boson pair (HH) production with one Higgs boson decaying to two bottom quarks and the other to two W bosons are presented. The search is done using proton-proton collisions data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$ recorded by the CMS detector at the LHC from 2016 to 2018. The final states considered include at least one leptonically decaying W boson. No evidence for the presence of a signal is observed and corresponding upper limits on the HH production cross section are derived. The limit on the inclusive cross section of the nonresonant HH production, assuming that the distributions of kinematic observables are as expected in the standard model (SM), is observed (expected) to be 14 (18) times the value predicted by the SM, at 95% confidence level. The limits on the cross section are also presented as functions of various Higgs boson coupling modifiers, and anomalous Higgs boson coupling scenarios. In addition, limits are set on the resonant HH production via spin-0 and spin-2 resonances within the mass range 250-900 GeV.
Observed and expected 95% CL upper limits on the production of new particles X of spin-2 and mass $m_X$ in the range 250 $\leq m_X \leq$ 900 GeV, which decay to Higgs boson pairs.
Observed and expected 95% CL upper limits on the production of new particles X of spin-0 and mass $m_X$ in the range 250 $\leq m_X \leq$ 900 GeV, which decay to Higgs boson pairs.
Observed and expected 95% CL upper limits on the inclusive nonresonant HH production cross section obtained for both single-lepton and dilepton channels, and from their combination
A search for an exotic decay of the Higgs boson to a Z boson and a light pseudoscalar particle (a), decaying to a pair of leptons and a pair of photons, respectively, is presented. The search is based on proton-proton collision data at a center-of-mass energy of $\sqrt{s}$ = 13 TeV, collected with the CMS detector and corresponding to an integrated luminosity of 138 fb$^{-1}$. The analysis probes pseudoscalar masses $m_\mathrm{a}$ between 1 and 30 GeV, leading to two pairs of well-isolated leptons and photons. Upper limits at 95% confidence level are set on the Higgs boson production cross section times its branching fraction to two leptons and two photons. The observed (expected) limits are in the range of 1.1-17.8 (1.7-17.9) fb within the probed $m_\mathrm{a}$ interval. An excess of data above the expected standard model background with a local (global) significance of 2.6 (1.3) standard deviations is observed for a mass hypothesis of $m_\mathrm{a}$ = 3 GeV. Limits on models involving axion-like particles, formulated as an effective field theory, are also reported.
Exclusion limits on the product of the production cross section and the branching fraction, as a function of the pseudoscalar mass hypothesis.
The polarizations of prompt and non-prompt J$/\psi$ and $\psi$(2S) mesons are measured in proton-proton collisions at $\sqrt{s}$ = 13 TeV, using data samples collected by the CMS experiment in 2017 and 2018, corresponding to a total integrated luminosity of 103.3 fb$^{-1}$. Based on the analysis of the dimuon decay angular distributions in the helicity frame, the polar anisotropy, $\lambda_\theta$, is measured as a function of the transverse momentum, $p_\mathrm{T}$, of the charmonium states, in the 25-120 and 20-100 GeV ranges for the J$/\psi$ and $\psi$(2S), respectively. The non-prompt polarizations agree with predictions based on the hypothesis that, for $p_\mathrm{T}$$\gtrsim$ 25 GeV, the non-prompt J$/\psi$ and $\psi$(2S) are predominantly produced in two-body B meson decays. The prompt results clearly exclude strong transverse polarizations, even for $p_\mathrm{T}$ exceeding 30 times the J$/\psi$ mass, where $\lambda_\theta$ tends to an asymptotic value around 0.3. Taken together with previous measurements, by CMS and LHCb at $\sqrt{s}$ = 7 TeV, the prompt polarizations show a significant variation with $p_\mathrm{T}$, at low $p_\mathrm{T}$.
prompt $\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi$ $\lambda_\theta$
non prompt $\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi$ $\lambda_\theta$
prompt $\psi(2S)$ $\lambda_\theta$
The J/$\psi$$\to$$\mu^+\mu^-\mu^+\mu^-$ decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb$^{-1}$. Normalizing to the J/$\psi$$\to$$\mu^+\mu^-$ decay mode leads to a branching fraction [10.1 $^{+3.3}_{-2.7}$ (stat) $\pm$ 0.4 (syst)] $\times$ 10$^{-7}$, a value that is consistent with the standard model prediction.
$\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi \to \mu\mu\mu\mu$ branching fraction
$\mathcal{B}(\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi \to \mu\mu\mu\mu)$ / $\mathcal{B}(\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi \to \mu\mu)$ ratio
The first observation of the concurrent production of two J/$\psi$ mesons in proton-nucleus collisions is presented. The analysis is based on a proton-lead (pPb) data sample recorded at a nucleon-nucleon center-of-mass energy of 8.16 TeV by the CMS experiment at the CERN LHC and corresponding to an integrated luminosity of 174.6 nb$^{-1}$. The two J/$\psi$ mesons are reconstructed in their $\mu^+\mu^-$ decay channels with transverse momenta $p_\mathrm{T}$$\gt$ 6.5 GeV and rapidity $\lvert y \rvert$$\lt$ 2.4. Events where one of the J/$\psi$ mesons is reconstructed in the dielectron channel are also considered in the search. The pPb $\to$ J/$\psi$J/$\psi$ + X process is observed with a significance of 5.3 standard deviations. The measured inclusive fiducial cross section, using the four-muon channel alone, is $\sigma$(pPb $\to$ J/$\psi$J/$\psi$ + X) = 22.0 $\pm$ 8.9 (stat) $\pm$ 1.5 (syst) nb. A fit of the data to the expected rapidity separation for pairs of J/$\psi$ mesons produced in single (SPS) and double (DPS) parton scatterings yields $\sigma^{\mathrm{pPb} \to \mathrm{J}/\psi\mathrm{J}/\psi +\mathrm{X}}_\text{SPS}$ = 16.5 $\pm$ 10.8 (stat) $\pm$ 0.1 (syst) nb and $\sigma^{\mathrm{pPb} \to \mathrm{J}/\psi\mathrm{J}/\psi + \mathrm{X}}_\text{DPS}$ = 5.4 $\pm$ 6.2 (stat) $\pm$ 0.4 (syst) nb, respectively. This latter result can be transformed into a lower bound on the effective DPS cross section, closely related to the squared average interparton transverse separation in the collision, of $\sigma_\text{eff}$$\gt$ 1.0 mb at 95% confidence level.
$\mathrm{pPb}\to\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi\,\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi+X$
$\mathrm{pPb}\to\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi\,\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi+X$
$\mathrm{pPb}\to\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi\,\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi+X$
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