The measurement of $K^{*}(892)^0$ resonance production via its $K^{+}\pi^{-}$ decay mode in inelastic p+p collisions at beam momentum 158 GeV/$c$ ($\sqrt{s_{NN}}=17.3$ GeV) is presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The $\textit{template}$ method was used to extract the $K^{*}(892)^0$ signal and double differential transverse momentum and rapidity spectra were obtained. The full phase-space mean multiplicity of $K^{*}(892)^0$ mesons was found to be $(78.44 \pm 0.38 \mathrm{(stat)} \pm 6.0 \mathrm{(sys)) \cdot 10^{-3}}$. The NA61/SHINE results are compared with the E$_{POS}$1.99 and Hadron Resonance Gas models as well as with world data from p+p and nucleus-nucleus collisions.

The backward angular distributions obtained in an experiment at the Zero Gradient Synchrotron of Argonne National Laboratory were used to systematically study the energy dependence of the 180° differential cross section for π+p elastic scattering in the center-of-mass energy region from 2159 to 3487 MeV. At each of 38 incident pion momenta between 2.0 and 6.0 GeV/c, a focusing spectrometer and scintillation counter hodoscopes were used to obtain differential cross sections for typically five pion scattering angles from 141° to 173° in the laboratory. Values for dσdΩ at 180° were then obtained by extrapolation. A resonance model and an interference model were used to perform fits to the energy dependence of dσdΩ (180°). Both models led to good fits to our data and yielded values for the masses, widths, parities, and the product of spin and elasticity for the Δ(2200), Δ(2420), Δ(2850), and Δ(3230) resonances. Our data confirm the existence of the Δ(3230) and require the negative-parity Δ(2200).

The differential cross sections for the elastic scattering of π+, π−, K+, K−, p, and p¯ on protons have been measured in the t interval -0.04 to -0.75 GeV2 at five momenta: 50, 70, 100, 140, and 175 GeV/c. The t distributions have been parametrized by the quadratic exponential form dσdt=Aexp(B|t|+C|t|2) and the energy dependence has been described in terms of a single-pole Regge model. The pp and K+p diffraction peaks are found to shrink with α′∼0.20 and ∼0.15 GeV−2, respectively. The p¯p diffraction peak is antishrinking while π±p and K−p are relatively energy-independent. Total elastic cross sections are calculated by integrating the differential cross sections. The rapid decline in σel observed at low energies has stopped and all six reactions approach relatively constant values of σel. The ratio of σelσtot approaches a constant value for all six reactions by 100 GeV, consistent with the predictions of the geometric-scaling hypothesis. This ratio is ∼0.18 for pp and p¯p, and ∼0.12-0.14 for π±p and K±p. A crossover is observed between K+p and K−p scattering at |t|∼0.19 GeV2, and between pp and p¯p at |t|∼0.11 GeV2. Inversion of the cross sections into impact-parameter space shows that protons are quite transparent to mesons even in head-on collisions. The probability for a meson to pass through a proton head-on without interaction inelastically is ∼20% while it is only ∼6% for an incident proton or antiproton. Finally, the results are compared with various quark-model predictions.

The ratio of π+p to pp elastic scattering is found to be smoothly varying over the range −t=0.03 to 0.4 GeV2. It is well fitted by a single exponential, indicating the forward behavior must be quite similar for the two reactions.

Hadroproduction of the Jψ and ψ′ states has been studied in 300-GeV/c proton, antiproton, and π±Li interactions. Both total and differential cross sections in xF and pT have been measured for the Jψ for the π±, proton, and antiproton interactions. The ratio of ψ′ to Jψ production has been determined for the four types of beam particles.

Measurements of elastic photoproduction cross sections for the J / ψ meson from 100 GeV to 375 GeV are presented. The results indicate that the cross section increases slowly in this range. The shape of the energy dependence agrees well with the photon-gluon fusion model prediction.

An analysis of high-transverse-momentum electrons using data from the Collider Detector at Fermilab (CDF) of p¯p collisions at s=1800 GeV yields values of the production cross section times branching ratio for W and Z0 bosons of σ(p¯p→WX→eνX)=2.19±0.04(stat)±0.21(syst) nb and σ(p¯p→Z0X→e+e−X)=0.209±0.013(stat)±0.017(syst) nb. Detailed descriptions of the CDF electron identification, background, efficiency, and acceptance are included. Theoretical predictions of the cross sections that include a mass for the top quark larger than the W mass, current values of the W and Z0 masses, and higher-order QCD corrections are in good agreement with these measured values.

We report a measurement of the electroweak parameters sin2θw and ϱ based on the ratios of neutral current to charged current events measured in the Fermilab narrow-band neutrino beam at energies of 30–240 GeV. The data are fully corrected for radiative effects, heavy-quark production, and other effects. The best value for sin2θw obtained, sin2θw=0.239±0.011, is consistent with the most recent values fromW andZ production, as well as from other neutrino experiments.

We present a measurement of the cross section for production of two or more jets as a function of dijet mass, based on an integrated luminosity of 86 pb^-1 collected with the Collider Detector at Fermilab. Our dijet mass spectrum is described within errors by next-to-leading order QCD predictions using CTEQ4HJ parton distributions, and is in good agreement with a similar measurement from the D0 experiment.

This paper reports a measurement of the cross section for the pair production of top quarks in ppbar collisions at sqrt(s) = 1.96 TeV at the Fermilab Tevatron. The data was collected from the CDF II detector in a set of runs with a total integrated luminosity of 1.1 fb^{-1}. The cross section is measured in the dilepton channel, the subset of ttbar events in which both top quarks decay through t -> Wb -> l nu b where l = e, mu, or tau. The lepton pair is reconstructed as one identified electron or muon and one isolated track. The use of an isolated track to identify the second lepton increases the ttbar acceptance, particularly for the case in which one W decays as W -> tau nu. The purity of the sample may be further improved at the cost of a reduction in the number of signal events, by requiring an identified b-jet. We present the results of measurements performed with and without the request of an identified b-jet. The former is the first published CDF result for which a b-jet requirement is added to the dilepton selection. In the CDF data there are 129 pretag lepton + track candidate events, of which 69 are tagged. With the tagging information, the sample is divided into tagged and untagged sub-samples, and a combined cross section is calculated by maximizing a likelihood. The result is sigma_{ttbar} = 9.6 +/- 1.2 (stat.) -0.5 +0.6 (sys.) +/- 0.6 (lum.) pb, assuming a branching ratio of BR(W -> ell nu) = 10.8% and a top mass of m_t = 175 GeV/c^2.

Using a prompt neutrino beam in which a nu_tau component was identified for the first time, the nu_tau magnetic moment was measured based on a search for an anomalous increase in the number of neutrino-electron interactions. One such event was observed when 2.3 were expected from background processes, giving an upper 90% confidence limit of 3.9x10^-7 Bohr magnetons.

A prompt photon cross section measurement from the Collider Detector at Fermilab experiment is presented. Detector and trigger upgrades, as well as 6 times the integrated luminosity compared with our previous publication, have contributed to a much more precise measurement and extended PT range. As before, QCD calculations agree qualitatively with the measured cross section, but the data has a steeper slope than the calculations.

The first prompt photon measurement from the CDF experiment at the Fermilab pp¯ Collider is presented. Two independent methods are used to measure the cross section: one for high transverse momentum (PT) and one for lower PT. Comparisons to various theoretical calculations are shown. The cross section agrees qualitatively with QCD calculations but has a steeper slope at low PT.

We have studied D* production mechanisms using data from a photoproduction experiment at the Fermilab Tagged Photon Spectrometer. A large sample of charged D*’s was selected via the clean signature of the cascade decay D*→D0π+ and subsequently D0→K−π+ or D0→K−π+π0. The cross section for the process γp→(D*++anything)p at an average energy of 105 GeV was measured to be 88±32 nb. Only (11±7)% of D*’s were found to be consistent with being accompanied solely by a D¯* or a D¯; the remaining events contain additional particles. The distribution of the production angle of the D* in the photon-fragmentation-system center of mass is strongly anisotropic and consistent with the form f(θ*)=cos4θ*. We set a limit on the associated-production-process cross section σ(γp→(D¯*−+anything)Λc) x)<60 nb (90% C.L.).

We study charged particle production in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta-phi space; toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. The 95% confidence level upper limit set on the branching fraction of the 125 GeV Higgs boson to invisible particles, $\mathcal{B}$(H $\to$ inv), is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous $\mathcal{B}$(H $\to$ inv) searches carried out at $\sqrt{s}$ = 7, 8, and 13 TeV in complementary production modes. The combined upper limit at 95% confidence level on $\mathcal{B}$(H $\to$ inv) is 0.15 (0.08 expected).

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and a fiducial mass of 5.5t. The data are found to be consistent with a background-only hypothesis, and limits are set on models for new physics including solar axion electron coupling, solar neutrino magnetic moment and millicharge, and electron couplings to galactic axion-like particles and hidden photons. Similar limits are set on weakly interacting massive particle (WIMP) dark matter producing signals through ionized atomic states from the Migdal effect.

The cross section for photon production in association with at least one jet containing a $b$-quark hadron has been measured in proton antiproton collisions at $\sqrt{s}=1.96$ TeV. The analysis uses a data sample corresponding to an integrated luminosity of 340 pb$^{-1}$ collected with the CDF II detector. Both the differential cross section as a function of photon transverse energy $E_T^{\gamma}$, $d \sigma$($p \overline{p} \to \gamma + \geq 1 b$-jet)/$d E_T^{\gamma}$ and the total cross section $\sigma$($p \overline{p} \to \gamma + \geq 1 b$-jet/ $E_T^{\gamma}> 20$ GeV) are measured. Comparisons to a next-to-leading order prediction of the process are presented.

The first measurement of the CP structure of the Yukawa coupling between the Higgs boson and $\tau$ leptons is presented. The measurement is based on data collected in proton-proton collisions at $\sqrt{s} =$ 13 TeV by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$. The analysis uses the angular correlation between the decay planes of $\tau$ leptons produced in Higgs boson decays. The effective mixing angle between CP-even and CP-odd $\tau$ Yukawa couplings is found to be $-$1 $\pm$ 19$^\circ$, compared to an expected value of 0 $\pm$ 21$^\circ$ at the 68.3% confidence level. The data disfavour the pure CP-odd scenario at 3.0 standard deviations. The results are compatible with predictions for the standard model Higgs boson.

Results for the Cabibbo suppressed semileptonic decays D 0 → π − e + ν and D 0 → π − μ + ν (charge conjugates are implied) are reported by Fermilab photoproduction experiment E687. We find 45.4 ± 13.3 events in the electron mode and 45.6 ± 11.8 in the muon mode. The relative branching ratio BR (D 0 →π − l + v) BR (D 0 →K − l + v) for the combined sample is measured to be 0.101 ± 0.020 (stat.) ± 0.003 (syst.) 14 .

The analyzing power AN in inclusive π0 production has been measured with use of the new 185-GeV/c Fermilab polarized proton beam. We obtain the value AN=0.10±0.03 for π0's in the kinematic region 0.2<xF<0.8 and 0.3<pT<1.2 GeV/c. In certain models of particle production this suggests that the spin of the proton is carried by its valence quarks.

The analyzing power A N of proton-proton, proton-hydrocarbon, and antiproton-hydrocarbon, scattering in the Coulomb-nuclear interference region has been measured using thhe 185 GeV/ c Fermilab polarized-proton and -antiproton beams. The results are found to be consistent with theoretical predictions within statistical uncertainties.

The analyzing power in inclusive charged pion production has been measured using the 200 GeV Fermilab polarized proton beam. A striking dependence in x F is observed in which A N increases from 0 to 0.42 with increasing x F for the π + data and decreases from 0 to −0.38 with increasing x F for π − data. The kinematic range covered is 0.2⩽ x F ⩽0.9 and 0.2⩽ p T ⩽2.0 GeV / c . In a simple model our data indicate that at large x F the transverse spin of the proton is correlated with that of its quark constituents.

The considerable polarization of hyperons produced at high xF has been known for a long time and has been interpreted with various theoretical models in terms of the constituents' spin. Recently, the analyzing power in inclusive Λ0 hyperon production has also been measured using the 200GeV/c Fermilab polarized proton beam. The covered kinematic range is 0.2≤xF≤1.0 and 0.1≤pT≤1.5GeV/c. The data indicate a negative asymmetry at large xF and moderate pT. These results can further test the current ideas on the underlying mechanisms for hyperon polarization.

The analyzing power AN of proton-proton elastic scattering in the Coulomb-nuclear interference region has been measured using the 200-GeV/c Fermilab polarized proton beam. A theoretically predicted interference between the hadronic non-spin-flip amplitude and the electromagnetic spin-flip amplitude is shown for the first time to be present at high energies in the region of 1.5 × 10−3 to 5.0 × 10−2 (GeV/c)2 four-momentum transfer squared, and our results are analyzed in connection with theoretical calculations. In addition, the role of possible contributions of the hadronic spin-flip amplitude is discussed.

This paper presents measurements of the production of Ds- mesons relative to Ds+ mesons as functions of x_F and square of p_t for a sample of 2445 Ds decays to phi pi. The Ds mesons were produced in Fermilab experiment E791 with 500 GeV/c pi- mesons incident on one platinum and four carbon foil targets. The acceptance-corrected integrated asymmetry in the x_F range -0.1 to 0.5 for Ds+- mesons is 0.032 +- 0.022 +- 0.022, consistent with no net asymmetry. The results, as functions of x_F and square of p_t, are compared to predictions and to the large production asymmetry observed for D+- mesons in the same experiment. These comparisons support the hypothesis that production asymmetries come from the fragmentation process and not from the charm quark production itself.

We present asymmetries between the production of D+ and D- mesons in Fermilab experiment E791 as a function of xF and pt**2. The data used here consist of 74,000 fully-reconstructed charmed mesons produced by a 500 GeV/c pi- beam on C and Pt foils. The measurements are compared to results of models which predict differences between the production of heavy-quark mesons that have a light quark in common with the beam (leading particles) and those that do not (non-leading particles). While the default models do not agree with our data, we can reach agreement with one of them, PYTHIA, by making a limited number of changes to parameters used.

We present a measurement of asymmetries in the production of $\Lambda_c^+$ and $\Lambda_c^-$ baryons in 500 GeV/c $\pi^-$--nucleon interactions from the E791 experiment at Fermilab. The asymmetries were measured as functions of Feynman x ($x_F$) and transverse momentum squared ($p_T^2$) using a sample of $1819 \pm 62$ $\Lambda_c$'s observed in the decay channel $\Lambda_c \to pK^-\pi^+$. We observe more $\Lambda_c^+$ than $\Lambda_c^-$ baryons, with an asymmetry of $(12.7\pm3.4\pm1.3) %$ independent of $x_F$ and $p_T^2$ in our kinematical range $(-0.1 < x_F < 0.6$ and $0.0 < p_T^2 < 8.0 (GeV/c)^2$). This $\Lambda_c$ asymmetry measurement is the first with data in both the positive and negative $x_F$ regions.

Using data from Fermilab fixed-target experiment E791, we have measured particle-antiparticle production asymmetries for lambda zero, cascade minus, and omega minus hyperons in pi minus-nucleon interactions at 500 GeV/c. The asymmetries are measured as functions of Feynman-x (x_F) and pt^2 over the ranges of -0.12 GE x_F LE 0.12 and 0 GE pt^2 LE 4 (GeV/c)^2. We find substantial asymmetries, even at x_F = 0. We also observe leading-particle- type asymmetries which qualitatively agree with theoretical predictions.

The path-length dependent parton energy loss within the dense partonic medium created in lead-lead collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV is studied by determining the azimuthal anisotropies for dijets with high transverse momentum. The data were collected by the CMS experiment in 2018 and correspond to an integrated luminosity of 1.69 nb$^{-1}$. For events containing back-to-back jets, correlations in relative azimuthal angle and pseudorapidity ($\eta$) between jets and hadrons, and between two hadrons, are constructed. The anisotropies are expressed as the Fourier expansion coefficients $v_n$, $n = $ 2-4 of these azimuthal distributions. The dijet $v_n$ values are extracted from long-range (1.5 $\lt$$\vert\Delta\eta\vert$$\lt$ 2.5) components of these correlations, which suppresses the background contributions from jet fragmentation processes. Positive dijet $v_2$ values are observed which increase from central to more peripheral events, while the $v_3$ and $v_4$ values are consistent with zero within experimental uncertainties.

The production of Z bosons associated with jets is measured in pp collisions at $\sqrt{s}$ = 13 TeV with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3 fb$^{-1}$. The multiplicity of jets with transverse momentum $p_\mathrm{T}$$\gt$ 30 GeV is measured for different regions of the Z boson's $p_\mathrm{T}$(Z), from lower than 10 GeV to higher than 100 GeV. The azimuthal correlation $\Delta \phi$ between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of $p_\mathrm{T}$(Z). The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low $p_\mathrm{T}$(Z) regions.

The structure of nucleons is multidimensional and depends on the transverse momenta, spatial geometry, and polarization of the constituent partons. Such a structure can be studied using high-energy photons produced in ultraperipheral heavy-ion collisions. The first measurement of the azimuthal angular correlations of exclusively produced events with two jets in photon-lead interactions at large momentum transfer is presented, a process that is considered to be sensitive to the underlying nuclear gluon polarization. This study uses a data sample of ultraperipheral lead-lead collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV, corresponding to an integrated luminosity of 0.38 nb$^{-1}$, collected with the CMS experiment at the LHC. The measured second harmonic of the correlation between the sum and difference of the two jet momenta is found to be positive, and rising, as the dijet momentum increases. A well-tuned model that has been successful at describing a wide range of proton scattering data from the HERA experiments fails to describe the observed correlations, suggesting the presence of gluon polarization effects.

Samples of inclusive photon+2 jet and photon+3 jet events collected by the D0 experiment with an integrated luminosity of about 1fb^-1 in ppbar collisions at sqrt{s}=1.96 TeV are used to measure cross sections as a function of the angle in the plane transverse to the beam direction between the transverse momentum (pT) of the photon+leading jet system (jets are ordered in pT) and pT of the other jet for photon+2 jet, or pT sum of the two other jets for photon+3 jet events. The results are compared to different models of multiple parton interactions (MPI) in the PYTHIA and SHERPA Monte Carlo (MC) generators. The data indicate a contribution from events with double parton (DP) interactions and are well described by predictions provided by the PYTHIA MPI models with pT-ordered showers and by SHERPA with the default MPI model. The photon+2 jet data are also used to determine the fraction of events with DP interactions as a function of the azimuthal angle and as a function of the second jet pT.

We report on measurements of the branching ratios of the decays B+→χc10(1P)K+ and B+→J/ψK+π+π−, where χc10(1P)→J/ψγ and J/ψ→μ+μ− in pp¯ collisions at s=1.8TeV. Using a data sample from an integrated luminosity of 110pb−1 collected by the Collider Detector at Fermilab we measure the branching ratios to be BR(B+→χc10(1P)K+)=15.5±5.4(stat)±1.5(syst)±1.3(br)×10−4 and BR(B+→J/ψK+π+π−)=6.9±1.8(stat)±1.1(syst)±0.4(br)×10−4 where (br) is due to the finite precision on BR(B+→J/ψK+), BR(χc10(1P)→J/ψγ) is used to normalize the signal yield, and (syst) encompasses all other systematic uncertainties.

From 2728 events of 205-GeV pp interactions found in 15 000 pictures taken with the 30-in. hydrogen bubble chamber at the National Accelerator Laboratory, a total cross section of 39.5±1.1 mb was measured. The mean charged-particle multiplicity for inelastic pp collisions was measured to be 7.65±0.17. The prong distribution from 2 to 22 prongs is broader than a Poisson distribution and has a width parameter f2−=〈n−(n−−1)〉−〈n−〉2=0.95±0.21.

The growth and development of “charged particle jets” produced in proton-antiproton collisions at 1.8 TeV  are studied over a transverse momentum range from 0.5 GeV/c to 50 GeV/c. A variety of leading (highest transverse momentum) charged jet observables are compared with the QCD Monte Carlo models HERWIG, ISAJET, and PYTHIA. The models describe fairly well the multiplicity distribution of charged particles within the leading charged jet, the size of the leading charged jet, the radial distribution of charged particles and transverse momentum around the leading charged jet direction, and the momentum distribution of charged particles within the leading charged jet. The direction of the leading “charged particle jet” in each event is used to define three regions of η−φ space. The “toward” region contains the leading “charged particle jet,” while the “away” region, on the average, contains the away-side jet. The “transverse” region is perpendicular to the plane of the hard 2-to-2 scattering and is very sensitive to the “underlying event” component of the QCD Monte Carlo models. HERWIG, ISAJET, and PYTHIA with their default parameters do not describe correctly all the properties of the “transverse” region.

We report on a measurement of the mean charged-particle multiplicity of jets in dijet events with dijet masses in the range 80–630GeV/c2, produced at the Tevatron in pp¯ collisions with s=1.8TeV and recorded by the Collider Detector at Fermilab. The data are fit to perturbative-QCD calculations carried out in the framework of the modified leading log approximation and the hypothesis of local parton-hadron duality. The fit yields values for two parameters in that framework: the ratio of parton multiplicities in gluon and quark jets, $r≡N_{partons}^{g−jet} / N_{partons}^{q−jet} = 1.7 \pm 0.3$, and the ratio of the number of charged hadrons to the number of partons in a jet, $K_{LPHD}^{charged} ≡ N_{hadrons}^{charged} / N_{partons} = 0.57 \pm 0.11$.

We report measurements of charm particle production asymmetries from the Fermilab photoproduction experiment E687. An asymmetry in the rate of production of charm versus anticharm particles is expected to arise primarily from fragmentation effects. We observe statistically significant asymmetries in the photoproduction of D + , D ∗+ and D 0 mesons and find small (but statistically weak) asymmetries in the production of the D s + meson and the Λ c + baryon. Our inclusive photoproduction asymmetries are compared to predictions from nonperturbative models of charm quark fragmentation.

We present total and differential cross sections for charm mesons produced in 600 GeV/ c π - emulsion interactions. Fits to d 2 σ / dx F dp T 2 ∞ (1−| x F |) n exp (- bp T 2 ) for 676 electronically reconstructed D mesons with x F >0 give n =4.25±0.24 ( stat .)±0.23 ( syst .) and b =0.76±0.03±0.03 ( GeV / c ) -2 . The total inclusive D + and D 0 cross sections are σ ( π - N → D ± ; x F >0) = 8.66±0.46±1.96 μb nucleon and σ(π - N→D 0 D 0 ; x F >0)=22.05±1.37±4.82μb nucleonk, where a linear dependence on the mean atomic weight of the target is assumed. These results are compared to next-to-leading order QCD predictions.

We report results on D 0 and D + production in proton-emulsion interactions at s =38.7 GeV. A fit to the form (1−| x F |) n exp (−bp 2 T ) yields n=6.9 +1.9 −1.8 and b=0.84 +0.10 −0.08 (GeV/ c ) −2 . The total inclusive cross section, is assuming linear A dependence, is measured to be 38±3(stat.) ±13 (sys.) μ b for the D 0 and 38±9±14 μ b for the D + . A comparison of these results with previous measurements indicates that nuclear effects do not strongly influence charm production. The predictions of QCD are in good agreement with our data.

We present results on charm pair correlations measured in proton-emulsion interactions at s =38.7 GeV. The predictions of leading order QCD for the distributions in invariant mass, rapidity gap, x F , and polar angle in the charm pair CMS are qualitatively consistent with our measurements. The mean p T of the pairs is equal within errors to that measured in dilepton production at the same energy and mass range.

The upgraded Collider Detector at Fermilab (CDF II) has a high bandwidth available for track based triggers. This capability in conjunction with the unprecedented integrated luminosity in excess of 1 fb −1 enables detailed studies of charm hadron production. CDF is now releasing first measurements of the prompt charm meson pair cross sections, which give access to QCD mechanisms by which charm quarks are produced in proton anti-proton collisions. Recent results on the spin alignment of J/ψ and ψ(2S) as well as on the relative production of the χc1(P1) and χc2(1P) challenge our understanding of the fragmentation of charm quarks into charmonium states.

A combination of measurements of the inclusive top-quark pair production cross-section performed by ATLAS and CMS in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV at the LHC is presented. The cross-sections are obtained using top-quark pair decays with an opposite-charge electron-muon pair in the final state and with data corresponding to an integrated luminosity of about 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and about 20 fb$^{-1}$ at $\sqrt{s}=8$ TeV for each experiment. The combined cross-sections are determined to be $178.5 \pm 4.7$ pb at $\sqrt{s}=7$ TeV and $243.3^{+6.0}_{-5.9}$ pb at $\sqrt{s}=8$ TeV with a correlation of 0.41, using a reference top-quark mass value of 172.5 GeV. The ratio of the combined cross-sections is determined to be $R_{8/7}= 1.363\pm 0.032$. The combined measured cross-sections and their ratio agree well with theory calculations using several parton distribution function (PDF) sets. The values of the top-quark pole mass (with the strong coupling fixed at 0.118) and the strong coupling (with the top-quark pole mass fixed at 172.5 GeV) are extracted from the combined results by fitting a next-to-next-to-leading-order plus next-to-next-to-leading-log QCD prediction to the measurements. Using a version of the NNPDF3.1 PDF set containing no top-quark measurements, the results obtained are $m_t^\text{pole} = 173.4^{+1.8}_{-2.0}$ GeV and $\alpha_\text{s}(m_Z)= 0.1170^{+ 0.0021}_{-0.0018}$.

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$ collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on the model, the combined result excludes a top squark mass up to 1325 GeV for a massless neutralino, and a neutralino mass up to 700 GeV for a top squark mass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV.

None

We have measured the cross sections $d^2\sigma/dP_T d\eta$ for production of isolated direct photons in \pbarp collisions at two different center-of-mass energies, 1.8 TeV and 0.63 TeV, using the Collider Detector at Fermilab (CDF). The normalization of both data sets agree with the predictions of Quantum Chromodynamics (QCD) for photon transverse momentum ($P_T$) of 25 GeV/c, but the shapes versus photon $P_T$ do not. These shape differences lead to a significant disagreement in the ratio of cross sections in the scaling variable $x_T (\equiv 2P_T/\sqrt{s}$). This disagreement in the $x_T$ ratio is difficult to explain with conventional theoretical uncertainties such as scale dependence and parton distribution parameterizations.

We present a measurement of the cross section and the first measurement of the heavy flavor content of associated direct photon + muon events produced in hadronic collisions. These measurements come from a sample of 1.8 TeV ppbar collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily due to Compton scattering process charm+gluon -> charm+photon, with the final state charm quark producing a muon. The cross section for events with a photon transverse momentum between 12 and 40 GeV/c is measured to be 46.8+-6.3+-7.5 pb, which is two standard deviations below the most recent theoretical prediction. A significant fraction of the events in the sample contain a final-state bottom quark. The ratio of charm to bottom production is measured to be 2.4+-1.2, in good agreement with QCD models.

The inclusive cross section for J/ψ production times the branching ratio B(J/ψ→μ+μ−) has been measured in the forward pseudorapidity region: B×dσ[p¯+p→J/ψ(pT>10GeV/c,2.1<|η|<2.6)+X]/dη=192±9(stat)±29(syst)pb. The results are based on 74.1±5.2pb−1 of data collected by the CDF Collaboration at the Fermilab Tevatron Collider. The measurements extend earlier measurements of the D0 Collaboration to higher pTJ/ψ. In the kinematic range where the experiments partially overlap, these data are in good agreement with previous measurements.

We have found 122 charmed-particle decays among 3855 neutrino interactions located in the fiducial volume of a hybrid emulsion spectrometer installed in the Fermilab wide-band neutrino beam. We obtain an average relative charmed-particle production cross section of σ(ν μ → c μ − ) σ(ν μ →μ − ) =4.9 −0.6 +0.7 % , at an average neutrino energy of 22 GeV. We also obtain a production rate of σ(ν μ → c c ν μ ) σ(ν μ →ν μ ) =0.13 −0.11 +0.31 % , if we assume that there was an undetected muon, a limit of σ(ν μ → c c μ − ) σ(ν μ → c μ − )<3% (90% CL ) can be obtained. Other cross section ratios and limits are also presented.

We present the results of a search for the production of light elements in p¯p collisions at the Fermilab Tevatron collider. Momentum, time of flight, and dE/dx measurements are used to distinguish nuclei from elementary particles. A production ratio for deuterium to hydrogen is calculated and compared to the primordial value of the big bang model. Some evidence for tritium is found and none for helium isotopes.