We determine the CKM matrix-element magnitude $|V_{cb}|$ using $\overline{B}^0\to D^{*+}\ell^-\bar\nu_\ell$ decays reconstructed in $189 \, \mathrm{fb}^{-1}$ of collision data collected by the Belle II experiment, located at the SuperKEKB $e^+e^-$ collider. Partial decay rates are reported as functions of the recoil parameter $w$ and three decay angles separately for electron and muon final states. We obtain $|V_{cb}|$ using the Boyd-Grinstein-Lebed and Caprini-Lellouch-Neubert parametrizations, and find $|V_{cb}|_\mathrm{BGL}=(40.57\pm 0.31 \pm 0.95\pm 0.58)\times 10^{-3}$ and $|V_{cb}|_\mathrm{CLN}=(40.13 \pm 0.27 \pm 0.93\pm 0.58 )\times 10^{-3}$ with the uncertainties denoting statistical components, systematic components, and components from the lattice QCD input, respectively. The branching fraction is measured to be ${\cal B}(\overline{B}^0\to D^{*+}\ell^-\bar\nu_\ell)=(4.922 \pm 0.023 \pm 0.220)\%$. The ratio of branching fractions for electron and muon final states is found to be $0.998 \pm 0.009 \pm 0.020$. In addition, we determine the forward-backward angular asymmetry and the $D^{*+}$ longitudinal polarization fractions. All results are compatible with lepton-flavor universality in the Standard Model.
Measured partial decay rates $\Delta\Gamma$ (in units of $10^{-15}$ GeV)
Average of normalized decay rates over $\overline{B}^0\to D^{*+} e^- \bar\nu_e$ and $\overline{B}^0\to D^{*+} \mu^- \bar\nu_\mu$ decays
Full experimental (statistical and systematic) correlations (in \%) of the partial decay rates for the $\overline{B}^0\to D^{*+} e^- \bar\nu_e$ and $\overline{B}^0\to D^{*+} \mu^- \bar\nu_\mu$ decays.
The longitudinal and transverse spin transfers to $\Lambda$ ($\overline{\Lambda}$) hyperons in polarized proton-proton collisions are expected to be sensitive to the helicity and transversity distributions, respectively, of (anti-)strange quarks in the proton, and to the corresponding polarized fragmentation functions. We report improved measurements of the longitudinal spin transfer coefficient, $D_{LL}$, and the transverse spin transfer coefficient, $D_{TT}$, to $\Lambda$ and $\overline{\Lambda}$ in polarized proton-proton collisions at $\sqrt{s}$ = 200 GeV by the STAR experiment at RHIC. The data set includes longitudinally polarized proton-proton collisions with an integrated luminosity of 52 pb$^{-1}$, and transversely polarized proton-proton collisions with a similar integrated luminosity. Both data sets have about twice the statistics of previous results and cover a kinematic range of $|\eta_{\Lambda(\overline{\Lambda})}|$$<$ 1.2 and transverse momentum $p_{T,{\Lambda(\overline{\Lambda})}}$ up to 8 GeV/$c$. We also report the first measurements of the hyperon spin transfer coefficients $D_{LL}$ and $D_{TT}$ as a function of the fractional jet momentum $z$ carried by the hyperon, which can provide more direct constraints on the polarized fragmentation functions.
'$D_{LL}$ as a function of $\cos\theta^{*}$ at $0 < \eta_{\Lambda(\overline{\Lambda})} < 1.2$ and $3 < p_{T} < 4 GeV/c$'
'$D_{TT}$ as a function of $\cos\theta^{*}$ at $0 < \eta_{jet} < 1.0$ and $0.5 < z < 0.7$'
'$\Lambda$ $D_{LL}$ as a function of $p_{T}$ at $0 < \eta_{\Lambda(\overline{\Lambda})} < 1.2$'
We present the first comprehensive tests of light-lepton universality in the angular distributions of semileptonic $B^0$-meson decays to charged spin-1 charmed mesons. We measure five angular-asymmetry observables as functions of the decay recoil that are sensitive to lepton-universality-violating contributions. We use events where one neutral $B$ is fully reconstructed in $\Upsilon\left(4S\right)\to{}B \overline{B}$ decays in data corresponding to $189~\mathrm{fb}^{-1}$ integrated luminosity from electron-positron collisions collected with the Belle II detector. We find no significant deviation from the standard model expectations.
Observed values of all angular asymmetry variables.
Full experimental covariance matrix of all angular asymmetry variables.
Additional spin-0 particles appear in many extensions of the standard model. We search for long-lived spin-0 particles $S$ in $B$-meson decays mediated by a $b\to s$ quark transition in $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance at the Belle II experiment. Based on a sample corresponding to an integrated luminosity of $189 \mathrm{\,fb}^{-1}$, we observe no evidence for signal. We set model-independent upper limits on the product of branching fractions $\mathrm{Br}(B^0\to K^*(892)^0(\to K^+\pi^-)S)\times \mathrm{Br}(S\to x^+x^-)$ and $\mathrm{Br}(B^+\to K^+S)\times \mathrm{Br}(S\to x^+x^-)$, where $x^+x^-$ indicates $e^+e^-, \mu^+\mu^-, \pi^+\pi^-$, or $K^+K^-$, as functions of $S$ mass and lifetime at the level of $10^{-7}$.
Expected and observed candidates for $\mathcal{B}($$B^+\to K^+S$$) \times$ $\mathcal{B}($$S\to e^+e^-$) as a function of the reduced mediator candidate mass.
Expected and observed candidates for $\mathcal{B}($$B^+\to K^+S$$) \times$ $\mathcal{B}($$S\to \mu^+\mu^-$) as a function of the reduced mediator candidate mass.
Expected and observed candidates for $\mathcal{B}($$B^+\to K^+S$$) \times$ $\mathcal{B}($$S\to \pi^+\pi^-$) as a function of the reduced mediator candidate mass.
The cross section for coherent photonuclear production of J/$\psi$ is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. Cross sections are presented in five different J/$\psi$ rapidity ranges within $|y|<4$, with the J/$\psi$ reconstructed via its dilepton decay channels. In some events the J/$\psi$ is not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range $17 < W_{\gamma\, \mathrm{Pb, n}} <920$ GeV, where $W_{\gamma\, \mathrm{Pb, n}}$ is the centre-of-mass energy per nucleon of the $\gamma\,\mathrm{Pb}$ system. This range corresponds to a Bjorken-$x$ interval spanning about three orders of magnitude: $ 1.1\times10^{-5}<x<3.3\times 10^{-2}$. In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies.
Measured coherent J/psi cross section for the 0N0N class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.
Measured coherent J/psi cross section for the 0NXN+XN0N class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.
Measured coherent J/psi cross section for the XN0N forward class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.
In relativistic heavy-ion collisions, a global spin polarization, $P_\mathrm{H}$, of $\Lambda$ and $\bar{\Lambda}$ hyperons along the direction of the system angular momentum was discovered and measured across a broad range of collision energies and demonstrated a trend of increasing $P_\mathrm{H}$ with decreasing $\sqrt{s_{NN}}$. A splitting between $\Lambda$ and $\bar{\Lambda}$ polarization may be possible due to their different magnetic moments in a late-stage magnetic field sustained by the quark-gluon plasma which is formed in the collision. The results presented in this study find no significant splitting at the collision energies of $\sqrt{s_{NN}}=19.6$ and $27$ GeV in the RHIC Beam Energy Scan Phase II using the STAR detector, with an upper limit of $P_{\bar{\Lambda}}-P_{\Lambda}<0.24$% and $P_{\bar{\Lambda}}-P_{\Lambda}<0.35$%, respectively, at a 95% confidence level. We derive an upper limit on the na\"ive extraction of the late-stage magnetic field of $B<9.4\cdot10^{12}$ T and $B<1.4\cdot10^{13}$ T at $\sqrt{s_{NN}}=19.6$ and $27$ GeV, respectively, although more thorough derivations are needed. Differential measurements of $P_\mathrm{H}$ were performed with respect to collision centrality, transverse momentum, and rapidity. With our current acceptance of $|y|<1$ and uncertainties, we observe no dependence on transverse momentum and rapidity in this analysis. These results challenge multiple existing model calculations following a variety of different assumptions which have each predicted a strong dependence on rapidity in this collision-energy range.
The first-order event-plane resolution determined by the STAR EPD as a function of collision centrality is roughly doubled in comparison to previous analyses using the STAR BBC. We see $R_{\rm EP}^{(1)}$ peak for mid-central collisions.
The mid-central $P_{\rm H}$ measurements reported in this work are shown alongside previous measurements in the upper panel, and are consistent with previous measurements at the energies studied here. The difference between integrated $P_{\bar{\Lambda}}$ and $P_{\Lambda}$ is shown at $\sqrt{s_{\rm{NN}}}$=19.6 and 27 GeV alongside previous measurements in the lower panel. The splittings observed with these high-statistics data sets are consistent with zero. Statistical uncertainties are represented as lines while systematic uncertainties are represented as boxes. The previous $P_{\bar{\Lambda}}-P_{\Lambda}$ result at $\sqrt{s_{\rm NN}}=7.7$ GeV is outside the axis range, but is consistent with zero within $2\sigma$.
$P_{\rm H}$ measurements are shown as a function of collision centrality at $\sqrt{s_{\rm NN}}$=19.6 and 27 GeV. Statistical uncertainties are represented as lines while systematic uncertainties are represented as boxes. $P_{\rm H}$ increases with collision centrality at $\sqrt{s_{\rm NN}}$=19.6 and 27 GeV, as expected from an angular-momentum-driven phenomenon.
Global polarizations ($P$) of $\Lambda$ ($\bar{\Lambda}$) hyperons have been observed in non-central heavy-ion collisions. The strong magnetic field primarily created by the spectator protons in such collisions would split the $\Lambda$ and $\bar{\Lambda}$ global polarizations ($\Delta P = P_{\Lambda} - P_{\bar{\Lambda}} < 0$). Additionally, quantum chromodynamics (QCD) predicts topological charge fluctuations in vacuum, resulting in a chirality imbalance or parity violation in a local domain. This would give rise to an imbalance ($\Delta n = \frac{N_{\text{L}} - N_{\text{R}}}{\langle N_{\text{L}} + N_{\text{R}} \rangle} \neq 0$) between left- and right-handed $\Lambda$ ($\bar{\Lambda}$) as well as a charge separation along the magnetic field, referred to as the chiral magnetic effect (CME). This charge separation can be characterized by the parity-even azimuthal correlator ($\Delta\gamma$) and parity-odd azimuthal harmonic observable ($\Delta a_{1}$). Measurements of $\Delta P$, $\Delta\gamma$, and $\Delta a_{1}$ have not led to definitive conclusions concerning the CME or the magnetic field, and $\Delta n$ has not been measured previously. Correlations among these observables may reveal new insights. This paper reports measurements of correlation between $\Delta n$ and $\Delta a_{1}$, which is sensitive to chirality fluctuations, and correlation between $\Delta P$ and $\Delta\gamma$ sensitive to magnetic field in Au+Au collisions at 27 GeV. For both measurements, no correlations have been observed beyond statistical fluctuations.
Figure 1
Figure 2ab
Figure 2c
The deconfined quark-gluon plasma (QGP) created in relativistic heavy-ion collisions enables the exploration of the fundamental properties of matter under extreme conditions. Non-central collisions can produce strong magnetic fields on the order of $10^{18}$ Gauss, which offers a probe into the electrical conductivity of the QGP. In particular, quarks and anti-quarks carry opposite charges and receive contrary electromagnetic forces that alter their momenta. This phenomenon can be manifested in the collective motion of final-state particles, specifically in the rapidity-odd directed flow, denoted as $v_1(\mathsf{y})$. Here we present the charge-dependent measurements of $dv_1/d\mathsf{y}$ near midrapidities for $\pi^{\pm}$, $K^{\pm}$, and $p(\bar{p})$ in Au+Au and isobar ($_{44}^{96}$Ru+$_{44}^{96}$Ru and $_{40}^{96}$Zr+$_{40}^{96}$Zr) collisions at $\sqrt{s_{\rm NN}}=$ 200 GeV, and in Au+Au collisions at 27 GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider. The combined dependence of the $v_1$ signal on collision system, particle species, and collision centrality can be qualitatively and semi-quantitatively understood as several effects on constituent quarks. While the results in central events can be explained by the $u$ and $d$ quarks transported from initial-state nuclei, those in peripheral events reveal the impacts of the electromagnetic field on the QGP. Our data put valuable constraints on the electrical conductivity of the QGP in theoretical calculations.
Directed flow of $p$ and $\bar{p}$ vs rapidity in Au+Au 200 GeV 50-80% centrality.
Directed flow of $p$ and $\bar{p}$ vs rapidity in Zr+Zr and Ru+Ru 200 GeV (combined) 50-80% centrality.
Directed flow of $p$ and $\bar{p}$ vs rapidity in Au+Au 27 GeV 50-80% centrality.
The polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons along the beam direction has been measured relative to the second and third harmonic event planes in isobar Ru+Ru and Zr+Zr collisions at $\sqrt{s_{NN}}$ = 200 GeV. This is the first experimental evidence of the hyperon polarization by the triangular flow originating from the initial density fluctuations. The amplitudes of the sine modulation for the second and third harmonic results are comparable in magnitude, increase from central to peripheral collisions, and show a mild $p_T$ dependence. The azimuthal angle dependence of the polarization follows the vorticity pattern expected due to elliptic and triangular anisotropic flow, and qualitatively disagree with most hydrodynamic model calculations based on thermal vorticity and shear induced contributions. The model results based on one of existing implementations of the shear contribution lead to a correct azimuthal angle dependence, but predict centrality and $p_T$ dependence that still disagree with experimental measurements. Thus, our results provide stringent constraints on the thermal vorticity and shear-induced contributions to hyperon polarization. Comparison to previous measurements at RHIC and the LHC for the second-order harmonic results shows little dependence on the collision system size and collision energy.
$sgn(\alpha_H)\langle\cos(\theta_p^{\ast})\rangle$ of $\Lambda$ and $\bar{\Lambda}$ as a function of hyperon azimuthal angle relative to the second-order event plane in isobar collisions at 200 GeV.
$sgn(\alpha_H)\langle\cos(\theta_p^{\ast})\rangle$ of $\Lambda$ and $\bar{\Lambda}$ as a function of hyperon azimuthal angle relative to the third-order event plane in isobar collisions at 200 GeV.
$P_z$ sine coefficients of $\Lambda+\bar{\Lambda}$ as a function of centrality in isobar collisions at 200 GeV.
Presented are the first measurements of the transverse single-spin asymmetries ($A_N$) for neutral pions and eta mesons in $p$+Au and $p$+Al collisions at $\sqrt{s_{_{NN}}}=200$ GeV in the pseudorapidity range $|\eta|<$0.35 with the PHENIX detector at the Relativistic Heavy Ion Collider. The asymmetries are consistent with zero, similar to those for midrapidity neutral pions and eta mesons produced in $p$+$p$ collisions. These measurements show no evidence of additional effects that could potentially arise from the more complex partonic environment present in proton-nucleus collisions.
Data from Figure 2 (a) of the $\pi^{0}$ transverse single-spin asymmetry in $\sqrt{s_{NN}}=200$ GeV $p^{\uparrow}+$Au and $p^{\uparrow}+$Al collisions as a function of $p_{T}$.
Data from Figure 2 (b) of the $\eta$ transverse single-spin asymmetry in $\sqrt{s_{NN}}=200$ GeV $p^{\uparrow}+$Au and $p^{\uparrow}+$Al collisions as a function of $p_{T}$.
A search for the electroweak production of a vector-like quark T$'$, decaying to a top quark and a Higgs boson is presented. The search is based on a sample of proton-proton collision events recorded at the LHC at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. This is the first T$'$ search that exploits the Higgs boson decay to a pair of photons. For narrow isospin singlet T$'$ states with masses up to 1.1 TeV, the excellent diphoton invariant mass resolution of 1-2% results in an increased sensitivity compared to previous searches based on the same production mechanism. The electroweak production of a T$'$ quark with mass up to 960 GeV is excluded at 95% confidence level, assuming a coupling strength $\kappa_\mathrm{T}$ = 0.25 and a relative decay width $\Gamma/M_{\mathrm{T}'}$ $\lt$ 5%.
The combined, leptonic plus hadronic, expected (dotted black) and observed (solid black) upper limits at 95% CL on $\sigma_{T^\prime bq} \times \mathcal{B}_{T^\prime \rightarrow tH}$ displayed as a function of $\rm{M}_{T^\prime}$. The green (yellow) band represents the 68% (95%) of the limit values expected under the background-only hypothesis. The theoretical cross sections for the singlet $T^\prime$ production with representative $\kappa_T$-values fixed at 0.1, 0.15, 0.2 and 0.25 (for $\Gamma/\rm{M}_{T^\prime} < 5\%$) are shown as solid red lines. The theoretical cross sections for the singlet $T^\prime$ production with $\Gamma/\rm{M}_{T^\prime}$ = 1 and 5% are also shown in table.
The combined, leptonic plus hadronic, expected (dotted black) and observed (solid black) upper limits at 95% CL on the $T^\prime$ coupling to third-generation quarks, $\kappa_{T}$, under the narrow width approximation (NWA) displayed as a function of $\rm{M}_{T^\prime}$. The green (yellow) band represents the 68% (95%) of the limit values expected under the background-only hypothesis. The theoretical $\kappa_{T}$ values corresponding to the $\Gamma/\rm{M}_{T^\prime}$-values fixed at 1, 2, 3, 4, and 5% are shown as red dashed lines.
The expected (dotted black) and observed (solid black) upper limits at 95% CL on $\sigma_{T^\prime bq(T^\prime \rightarrow tH)}$ in the leptonic channel displayed as a function of $\rm{M}_{T^\prime}$. The green (yellow) band represents the 68% (95%) of the limit values expected under the background-only hypothesis. The theoretical cross sections for the singlet $T^\prime$ production with representative $\kappa_T$-values fixed at 0.1, 0.15, 0.2 and 0.25 (for $\Gamma/\rm{M}_{T^\prime} < 5\%$) are shown as solid red lines.
A precision measurement of the matrix elements for $\eta\to\pi^+\pi^-\pi^0$ and $\eta\to\pi^0\pi^0\pi^0$ decays is performed using a sample of $(10087\pm44)\times10^6$$J/\psi$ decays collected with the BESIII detector. The decay $J/\psi \to \gamma \eta$ is used to select clean samples of 631,686 $\eta\to\pi^+\pi^-\pi^0$ decays and 272,322 $\eta\to\pi^0\pi^0\pi^0$ decays. The matrix elements for both channels are in reasonable agreement with previous measurements. The non-zero $gX^2Y$ term for the decay mode $\eta\to\pi^+\pi^-\pi^0$ is confirmed, as reported by the KLOE Collaboration, while the other higher-order terms are found to be insignificant. Dalitz plot asymmetries in the $\eta\to\pi^+\pi^-\pi^0$ decay are also explored and are found to be consistent with charge conjugation invariance. In addition, a cusp effect is investigated in the $\eta\to\pi^0\pi^0\pi^0$ decay, and no obvious structure around the $\pi^+\pi^-$ mass threshold is observed.
The acceptance corrected $\eta\to\pi^+\pi^-\pi^0$ data from 10 billion $J/\psi$ events collected at BESIII and the corresponding statistical uncertainties in the Dalitz plot variables $X$ and $Y$. The data are divided into $20\times20$ bins in $X$ and $Y$, and only the bins with non-zero event are listed in the table. The first two columns in the table are the center values of $X$ and $Y$, respectively. The last column is the acceptance corrected data and the corresponding statistical uncertainties.
The acceptance corrected $\eta\to\pi^0\pi^0\pi^0$ data from 10 billion $J/\psi$ events collected at BESIII and the corresponding statistical uncertainties in the Dalitz plot variables $X$ and $Y$. The data are divided into $20\times20$ bins in $X$ and $Y$, and only the bins with non-zero event are listed in the table. The first two columns in the table are the center values of $X$ and $Y$, respectively. The last column is the acceptance corrected data and the corresponding statistical uncertainties.
The fractions of non-prompt (i.e. originating from beauty-hadron decays) D$^0$ and D$^+$ mesons with respect to the inclusive yield are measured as a function of the charged-particle multiplicity in proton$-$proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV with the ALICE detector at the LHC. The results are reported in intervals of transverse momentum ($p_{\rm T}$) and integrated in the range $1 < p_{\rm T} < 24$ GeV/$c$. The fraction of non-prompt D$^0$ and D$^+$ mesons is found to increase slightly as a function of $p_{\rm T}$ in all the measured multiplicity intervals, while no significant dependence on the charged-particle multiplicity is observed. In order to investigate the production and hadronisation mechanisms of charm and beauty quarks, the results are compared to PYTHIA 8 as well as EPOS 3 and EPOS 4 Monte Carlo simulations, and to calculations based on the colour glass condensate including three-pomeron fusion.
Measurements of the suppression and correlations of dijets is performed using 3 $\mu$b$^{-1}$ of Xe+Xe data at $\sqrt{s_{\mathrm{NN}}} = 5.44$ TeV collected with the ATLAS detector at the LHC. Dijets with jets reconstructed using the $R=0.4$ anti-$k_t$ algorithm are measured differentially in jet $p_{\text{T}}$ over the range of 32 GeV to 398 GeV and the centrality of the collisions. Significant dijet momentum imbalance is found in the most central Xe+Xe collisions, which decreases in more peripheral collisions. Results from the measurement of per-pair normalized and absolutely normalized dijet $p_{\text{T}}$ balance are compared with previous Pb+Pb measurements at $\sqrt{s_{\mathrm{NN}}} =5.02$ TeV. The differences between the dijet suppression in Xe+Xe and Pb+Pb are further quantified by the ratio of pair nuclear-modification factors. The results are found to be consistent with those measured in Pb+Pb data when compared in classes of the same event activity and when taking into account the difference between the center-of-mass energies of the initial parton scattering process in Xe+Xe and Pb+Pb collisions. These results should provide input for a better understanding of the role of energy density, system size, path length, and fluctuations in the parton energy loss.
The centrality intervals in Xe+Xe collisions and their corresponding TAA with absolute uncertainties.
The centrality intervals in Xe+Xe and Pb+Pb collisions for matching SUM ET FCAL intervals and respective TAA values for Xe+Xe collisions.
The performance of the jet energy scale (JES) for jets with $|y| < 2.1$ evaluated as a function of pT_truth in different centrality bins. Simulated hard scatter events were overlaid onto events from a dedicated sample of minimum-bias Xe+Xe data.
The mass of the top quark is measured in 36.3 fb$^{-1}$ of LHC proton-proton collision data collected with the CMS detector at $\sqrt{s}$ = 13 TeV. The measurement uses a sample of top quark pair candidate events containing one isolated electron or muon and at least four jets in the final state. For each event, the mass is reconstructed from a kinematic fit of the decay products to a top quark pair hypothesis. A profile likelihood method is applied using up to four observables to extract the top quark mass. The top quark mass is measured to be 171.77 $\pm$ 0.37 GeV. This approach significantly improves the precision over previous measurements.
Fit values for the top quark mass value and the nuisance parameters corresponding to the different uncertainty sources. All nuisance parameters have a prefit uncertainty of 1.
Covariance matrix for the top quark mass value and the nuisance parameters corresponding to the different uncertainty sources. All nuisance parameters have a prefit uncertainty of 1. The (statistical) uncertainty in mTop in the matrix includes the contributions from limited simulation sample sizes.
A search for flavor-changing neutral-current couplings between a top quark, an up or charm quark and a $Z$ boson is presented, using proton-proton collision data at $\sqrt{s} = 13$ TeV collected by the ATLAS detector at the Large Hadron Collider. The analyzed dataset corresponds to an integrated luminosity of 139 fb$^{-1}$. The search targets both single-top-quark events produced as $gq\rightarrow tZ$ (with $q = u, c$) and top-quark-pair events, with one top quark decaying through the $t \rightarrow Zq$ channel. The analysis considers events with three leptons (electrons or muons), a $b$-tagged jet, possible additional jets, and missing transverse momentum. The data are found to be consistent with the background-only hypothesis and 95% confidence-level limits on the $t \rightarrow Zq$ branching ratios are set, assuming only tensor operators of the Standard Model effective field theory framework contribute to the $tZq$ vertices. These are $6.2 \times 10^{-5}$ ($13\times 10^{-5}$) for $t\rightarrow Zu$ ($t\rightarrow Zc$) for a left-handed $tZq$ coupling, and $6.6 \times 10^{-5}$ ($12\times 10^{-5}$) in the case of a right-handed coupling. These results are interpreted as 95% CL upper limits on the strength of corresponding couplings, yielding limits for $|C_{uW}^{(13)*}|$ and $|C_{uB}^{(13)*}|$ ($|C_{uW}^{(31)}|$ and $|C_{uB}^{(31)}|$) of 0.15 (0.16), and limits for $|C_{uW}^{(23)*}|$ and $|C_{uB}^{(23)*}|$ ($|C_{uW}^{(32)}|$ and $|C_{uB}^{(32)}|$) of 0.22 (0.21), assuming a new-physics energy scale $\Lambda_\text{NP}$ of 1 TeV.
Summary of the signal strength $\mu$ parameters obtained from the fits to extract LH and RH results for the FCNC tZu and tZc couplings. For the reference branching ratio, the most stringent limits are used.
Observed and expected 95% CL limits on the FCNC $t\rightarrow Zq$ branching ratios and the effective coupling strengths for different vertices and couplings (top eight rows). For the latter, the energy scale is assumed to be $\Lambda_{NP}$ = 1 TeV. The bottom rows show, for the case of the FCNC $t\rightarrow Zu$ branching ratio, the observed and expected 95% CL limits when only one of the two SRs, either SR1 or SR2, and all CRs are included in the likelihood.
Comparison between data and background prediction before the fit (Pre-Fit) for the mass of the SM top-quark candidate in SR1. The uncertainty band includes both the statistical and systematic uncertainties in the background prediction. The four FCNC LH signals are also shown separately, normalized to five times the cross-section corresponding to the most stringent observed branching ratio limits. The first (last) bin in all distributions includes the underflow (overflow). The lower panels show the ratios of the data (Data) to the background prediction (Bkg.).
The production of $\pi^\pm$, ${\rm K}^\pm$, and $(\overline{\rm p})$p is measured in pp collisions at $\sqrt{s}=13$ TeV in different topological regions. Particle transverse momentum ($p_{\rm T}$) spectra are measured in the ``toward'', ``transverse'', and ``away'' angular regions defined with respect to the direction of the leading particle in the event. While the toward and away regions contain the fragmentation products of the near-side and away-side jets, respectively, the transverse region is dominated by particles from the Underlying Event (UE). The relative transverse activity classifier, $R_{\rm T}=N_{\rm T}/\langle N_{\rm T}\rangle$, is used to group events according to their UE activity, where $N_{\rm T}$ is the measured charged-particle multiplicity per event in the transverse region and $\langle N_{\rm T}\rangle$ is the mean value over all the analysed events. The first measurements of identified particle $p_{\rm T}$ spectra as a function of $R_{\rm T}$ in the three topological regions are reported. The yield of high transverse momentum particles relative to the $R_{\rm T}$-integrated measurement decreases with increasing $R_{\rm T}$ in both the toward and away regions, indicating that the softer UE dominates particle production as $R_{\rm T}$ increases and validating that $R_{\rm T}$ can be used to control the magnitude of the UE. Conversely, the spectral shapes in the transverse region harden significantly with increasing $R_{\rm T}$. This hardening follows a mass ordering, being more significant for heavier particles. The $p_{\rm T}$-differential particle ratios $({\rm p+\overline{p}})/(\pi^+ +\pi^-)$ and $({\rm K^+ +K^-})/(\pi^+ +\pi^-)$ in the low UE limit $(R_{\rm T}\rightarrow 0)$ approach expectations from Monte Carlo generators such as PYTHIA 8 with Monash 2013 tune and EPOS LHC, where the jet-fragmentation models have been tuned to reproduce ${\rm e^+ e^-}$ results.
$N_{\mathrm{T}}$ probability distribution in the transverse region using events with leading particles $(p_{\mathrm{T}}^{\mathrm{leading}} \geq 5~\mathrm{GeV}/c)$ in the pseudorapidity interval $|\eta|<0.8$ in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.
$R_{\mathrm{T}}$ probability distribution in the transverse region using events with leading particles $(p_{\mathrm{T}}^{\mathrm{leading}} \geq 5~\mathrm{GeV}/c)$ in the pseudorapidity interval $|\eta|<0.8$ in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.
$\pi^{+}+\pi^{-}$ transverse momentum spectrum for events with $0 \leq R_{\mathrm{T}} < 5$ in the Toward region in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.
We present a measurement of the differential shapes of exclusive $B\to D^* \ell \bar{\nu}_\ell$ ($B = B^-, \bar{B}^0 $ and $\ell = e, \mu$) decays with hadronic tag-side reconstruction for the full Belle data set of $711\,\mathrm{fb}^{-1}$ integrated luminosity. We extract the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parameters and use an external input for the absolute branching fractions to determine the Cabibbo-Kobayashi-Maskawa matrix element and find $|V_{cb}|_\mathrm{CLN} = (40.1\pm0.9)\times 10^{-3}$ and $|V_{cb}|_\mathrm{BGL} = (40.6\pm 0.9)\times 10^{-3}$ with the zero-recoil lattice QCD point $\mathcal{F}(1) = 0.906 \pm 0.013$. We also perform a study of the impact of preliminary beyond zero-recoil lattice QCD calculations on the $|V_{cb}|$ determinations. Additionally, we present the lepton flavor universality ratio $R_{e\mu} = \mathcal{B}(B \to D^* e \bar{\nu}_e) / \mathcal{B}(B \to D^* \mu \bar{\nu}_\mu) = 0.990 \pm 0.021 \pm 0.023$, the electron and muon forward-backward asymmetry and their difference $\Delta A_{FB}=0.022\pm0.026\pm 0.007$, and the electron and muon $D^*$ longitudinal polarization fraction and their difference $\Delta F_L^{D^*} = 0.034 \pm 0.024 \pm 0.007$. The uncertainties quoted correspond to the statistical and systematic uncertainties, respectively.
Bins used in the average spectrum (equivalent to the B0 case binning)
Bins for each data point for B0 and B+ cases separately.
The fully averaged measured shape. The 40 entries correspond to 10 bins in w, cosThetaL, cosThetaV, and chi. For the binning see the file 'Binning.yaml'.
A search for physics beyond the standard model (SM) in final states with an electron or muon and missing transverse momentum is presented. The analysis uses data from proton-proton collisions at a centre-of-mass energy of 13 TeV, collected with the CMS detector at the LHC in 2016–2018 and corresponding to an integrated luminosity of 138 fb−1. No significant deviation from the SM prediction is observed. Model-independent limits are set on the production cross section of W’ bosons decaying into lepton-plus-neutrino final states. Within the framework of the sequential standard model, with the combined results from the electron and muon decay channels a W’ boson with mass less than 5.7 TeV is excluded at 95% confidence level. Results on a SM precision test, the determination of the oblique electroweak W parameter, are presented using LHC data for the first time. These results together with those from the direct W’ resonance search are used to extend existing constraints on composite Higgs scenarios. This is the first experimental exclusion on compositeness parameters using results from LHC data other than Higgs boson measurements.
Product of signal selection efficiency and acceptance as a function of resonance mass for a SSM WPRIME decaying to electron or muon plus neutrino.It is calculated as the number of WPRIME signal events passing the selection process over the number of generated events. In the selection process there is no requirement on a minimum $M_T$ applied. The SSM WPRIME signal samples have been generated with PYTHIA 8.2. More details in paper
Observed and expected number of events in the electron and muon channels, collected during three years (2016, 2017, and 2018), for selected values of $M_T$ thresholds. The statistical and systematic uncertainties are added in quadrature providing the total uncertainty.
Observed and expected-from-SM number of events in the electron and muon channels, collected during three years (2016, 2017, and 2018), for two steps in the selection procedure: 1) one high-quality high-$p_T$ lepton with $p_T$ > 240(53) GeV for E(MU), and no other lepton in the event, with $M_T$ > 400(120) GeV for events with E(MU). 2) additionally the ratio of the lepton $p_T$ and $p_T^{miss}$ must be 0.4 < $p_T$/$p_T^{miss}$ < 1.5 and the azimuthal angular difference between them, ${\Delta\phi}$> 2.5. The signal yield for an SSM WPRIME of mass 5.6 TeV is also included.
A measurement is presented for the electroweak production of a W boson, a photon ($\gamma$), and two jets (j) in proton-proton collisions. The leptonic decay of the W boson is selected by requiring one identified electron or muon and large missing transverse momentum. The two jets are required to have large invariant dijet mass and large separation in pseudorapidity. The measurement is performed with the data collected by the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The cross section for the electroweak W$\gamma$jj production is 23.5 $^{+4.9}_{-4.7}$ fb, whereas the total cross section for W$\gamma$jj production is 113 $\pm$ 13 fb. Differential cross sections are also measured with the distributions unfolded to the particle level. All results are in agreement with the standard model expectations. Constraints are placed on anomalous quartic gauge couplings (aQGCs) in terms of dimension-8 effective field theory operators. These are the most stringent limits to date on the aQGCs parameters $f_\mathrm{M,2-5}$$/$$\Lambda^4$ and $f_\mathrm{T,6-7}$$/$$\Lambda^4$.
The 2D distributions used in the fit for the total EW W$\gamma$ cross section measurement. The hatched bands represent the systematic uncertainties in the predicted yields. The expectation is shown after the fit to the data and overflow bin has been considered.
The 2D distributions used in the fit for the total EW W$\gamma$ cross section measurement. The hatched bands represent the systematic uncertainties in the predicted yields. The expectation is shown after the fit to the data and overflow bin has been considered.
Differential cross sections for the EW W$\gamma$jj production. Given that the ranges of some variables extend to infinity, the last bins accommodate all the events up to infinity as marked by the bin label.
A search for physics beyond the standard model (SM) in the final state with a hadronically decaying tau lepton and a neutrino is presented. This analysis is based on data recorded by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, corresponding to a total integrated luminosity of 138 fb$^{=1}$. The transverse mass spectrum is analyzed for the presence of new physics. No significant deviation from the SM prediction is observed. Limits are set on the production cross section of a W' boson decaying into a tau lepton and a neutrino. Lower limits are set on the mass of the sequential SM-like heavy charged vector boson and the mass of a quantum black hole. Upper limits are placed on the couplings of a new boson to the SM fermions. Constraints are put on a nonuniversal gauge interaction model and an effective field theory model. For the first time, upper limits on the cross section of $t$-channel leptoquark (LQ) exchange are presented. These limits are translated into exclusion limits on the LQ mass and on its coupling in the $t$-channel. The sensitivity of this analysis extends into the parameter space of LQ models that attempt to explain the anomalies observed in B meson decays. The limits presented for the various interpretations are the most stringent to date. Additionally, a model-independent limit is provided.
The transverse mass distribution of $ au$ leptons and missing transverse momentum observed in the Run-2 data (black dots with statistical uncertainty) as well as the expectation from SM processes (stacked histograms). Different signal hypotheses normalized to 10 fb$^{-1}$ are illustrated as dashed lines for exemplary SSM W$\prime$ boson, QBH and EFT signal hypotheses. The ratios of the background-subtracted data yields to the expected background yields are presented in the lower panel. The combined statistical and systematic uncertainties in the background are represented by the grey shaded band in the ratio panel.
Bayesian upper exclusion limits at 95% CL on the product of the cross section and branching fraction of a W$\prime$ boson decaying to a $\tau$ lepton and a neutrino in the SSM model. For this model, W$\prime$ boson masses of up to 4.8 TeV can be excluded. The limit is given by the intersection of the observed (solid) limit and the theoretical cross section (blue dotted curve). The 68 and 95% quantiles of the limits are represented by the green and yellow bands, respectively. The $\sigma \mathcal{B}$ for an SSM W' boson, along with its associated uncertainty, calculated at NNLO precision in QCD is shown.
Bayesian 95% CL model-independent upper limit on the product of signal cross sections and branching fraction for the $\tau+\nu$ decay for a back-to-back $\tau$ lepton plus $p_{T}^{miss}$ topology. To calculate this limit, all events for signal, background, and data are summed starting from a minimum $m_{T}$ threshold and then divided by the total number of events. No assumption on signal shape is included in this limit. The expected (dashed line) and observed (solid line) limits are shown as well as the 68% and 95% CL uncertainty bands (green and yellow, respectively).
The $L_{\mu}-L_{\tau}$ extension of the standard model predicts the existence of a lepton-flavor-universality-violating $Z^{\prime}$ boson that couples only to the heavier lepton families. We search for such a $Z^\prime$ through its invisible decay in the process $e^+ e^- \to \mu^+ \mu^- Z^{\prime}$. We use a sample of electron-positron collisions at a center-of-mass energy of 10.58GeV collected by the Belle II experiment in 2019-2020, corresponding to an integrated luminosity of 79.7fb$^{-1}$. We find no excess over the expected standard-model background. We set 90$\%$-confidence-level upper limits on the cross section for this process as well as on the coupling of the model, which ranges from $3 \times 10^{-3}$ at low $Z^{\prime}$ masses to 1 at $Z^{\prime}$ masses of 8$GeV/c^{2}$.
Observed 90% CL upper limits on the cross section $\sigma (e^+ e^- \to \mu^+ \mu^- Z', Z' \to $ invisible) as functions of the $Z'$ mass for the cases of negligible $\Gamma_{Z'}$ and for $\Gamma_{Z'} = 0.1 M_{Z'}$. Also shown are previous limits from Belle II.
Observed 90% CL upper limits on the coupling $g'$ for the fully invisible $L_\mu − L_\tau$ model as functions of the $Z'$ mass for the cases of negligible $\Gamma_{Z'}$ and for $\Gamma_{Z'} = 0.1 M_{Z'}$. Also shown are previous limits from NA64-e and Belle II searches. The red band shows the region that explains the muon anomalous magnetic moment $(g - 2)_\mu \pm 2 \sigma$. The vertical dashed line indicates the limit beyond which the hypothesis $B(Z' \to \chi\bar{\chi}) \approx 1$ is not respected in the negligible $\Gamma_{Z'}$ case.
Observed 90% CL upper limits on the coupling $g'$ for the vanilla $L_\mu − L_\tau$ model as functions of the $Z'$ mass. Also shown are previous limits from Belle II and NA64-e searches for invisible $Z'$ decays, and from Belle, BaBar and CMS searches for $Z'$ decays to muons (at 95% CL). The red band shows the region that explains the muon anomalous magnetic moment $(g - 2)_\mu \pm 2 \sigma$.
A search is performed for exclusive high-mass $\gamma\gamma$$\to$ WW and $\gamma\gamma$$\to$ ZZ production in proton-proton collisions using intact forward protons reconstructed in near-beam detectors, with both weak bosons decaying into boosted and merged jets. The analysis is based on a sample of proton-proton collisions collected by the CMS and TOTEM experiments at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 100 fb$^{-1}$. No excess above the standard model background prediction is observed, and upper limits are set on the pp $\to$ pWWp and pp $\to$ pZZp cross sections in a fiducial region defined by the diboson invariant mass $m$(VV) $\lt$ 1 TeV (with V = W, Z) and proton fractional momentum loss 0.04 $\lt$$\xi$$\lt$ 0.20. The results are interpreted as new limits on dimension-6 and dimension-8 anomalous quartic gauge couplings.
Expected and observed upper limits on the AQGC operators $a^W_0/\Lambda^2$, with no unitarization. The $y$ axis shows the limit on the ratio of the observed cross section to the cross section predicted for each anomalous coupling value ($\sigma_\mathrm{AQGC}$).
Expected and observed upper limits on the AQGC operators $a^W_C/\Lambda^2$, with no unitarization. The $y$ axis shows the limit on the ratio of the observed cross section to the cross section predicted for each anomalous coupling value ($\sigma_\mathrm{AQGC}$).
Expected and observed upper limits on the AQGC operators $a^Z_0/\Lambda^2$, with no unitarization. The $y$ axis shows the limit on the ratio of the observed cross section to the cross section predicted for each anomalous coupling value ($\sigma_\mathrm{AQGC}$).
The transverse-momentum ($p_{\rm T}$) spectra and coalescence parameters $B_2$ of (anti)deuterons are measured in pp collisions at $\sqrt{s} = 13$ TeV for the first time in and out of jets. In this measurement, the direction of the leading particle with the highest $p_{\rm T}$ in the event ($p_{\rm T}^{\rm{ lead}} > 5$ GeV/$c$) is used as an approximation for the jet axis. The event is consequently divided into three azimuthal regions and the jet signal is obtained as the difference between the Toward region, that contains jet fragmentation products in addition to the underlying event (UE), and the Transverse region, which is dominated by the UE. The coalescence parameter in the jet is found to be approximately a factor of 10 larger than that in the underlying event. This experimental observation is consistent with the coalescence picture and can be attributed to the smaller average phase-space distance between nucleons inside the jet cone as compared to the underlying event. The results presented in this Letter are compared to predictions from a simple nucleon coalescence model, where the phase space distributions of nucleons are generated using PYTHIA 8 with the Monash 2013 tuning, and to predictions from a deuteron production model based on ordinary nuclear reactions with parametrized energy-dependent cross sections tuned on data. The latter model is implemented in PYTHIA 8.3. Both models reproduce the observed large difference between in-jet and out-of-jet coalescence parameters, although the almost flat trend of the $B^{\rm Jet}_2$ is not reproduced by the models, which instead give a decreasing trend.
Transverse momentum spectra for the transverse azimuthal regions. Events with a leading track with PT>5 GEV at midrapidity are selected. The spectrum is shown in Figure 1 (left panel).
Transverse momentum spectra for the toward azimuthal regions. Events with a leading track with PT>5 GEV at midrapidity are selected. The spectrum is shown in Figure 1 (left panel).
Transverse momentum spectra for the away azimuthal regions. Events with a leading track with PT>5 GEV at midrapidity are selected. The spectrum is shown in Figure 1 (left panel).
The production of inclusive, prompt and non-prompt J/$\psi$ was studied for the first time at midrapidity ($ -1.37 < y_{\rm cms} < 0.43$) in p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 8.16$ TeV with the ALICE detector at the LHC. The inclusive J/$\psi$ mesons were reconstructed in the dielectron decay channel in the transverse momentum ($p_{\rm T}$) interval $0 < p_{\rm T} < 14$ GeV/$c$ and the prompt and non-prompt contributions were separated on a statistical basis for $p_{\rm T} > 2$ GeV/$c$. The study of the J/$\psi$ mesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of $689 \pm 13 \mu{\rm b}^{-1}$. The proton$-$proton reference cross section for inclusive J/$\psi$ was obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing the $p_{\rm T}$-differential J/$\psi$ production cross sections. The $p_{\rm T}$-differential nuclear modification factors $R_{\rm pPb}$ of inclusive, prompt, and non-prompt J/$\psi$ are consistent with unity and described by theoretical models implementing only nuclear shadowing.
d$^2\sigma$/d$y$d$p_{\rm T}$ in bins of $p_{\mathrm{T}}^{J/\psi}$ for inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV.
Nuclear modification factor ($R_{pPb}$) of inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV at midrapidity.
$p_\mathrm{T}$ integrated nuclear modification factor ($R_{pPb}$) of inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV at midrapidity.
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