Search

The top quark was rst observed in 1995 in the CDF and D0 experiments at the Fermilab $$p\bar{p}$$ Tevatron collider. In the intervening 25 years much has been learned about this heaviest of all known fundamental particles. Its properties thus far conform to the expectations of the standard model but its large mass is suggestive that its study is an ideal place for searches for new physics outside the current paradigm.

The TOTEM collaboration at the Large Hadron Collider, together with the D0 collaboration at the Tevatron collider at Fermilab, have announced the discovery of the odderon – a bound state of three gluons that was predicted about 50 years ago. The result was presented at CERN on March 5 and follows the joint submission in December 2020 of a CERN and Fermilab preprints by TOTEM and D0 reporting this observation. States comprising several gluons are usually called “glueballs”, and are peculiar objects made only of the carriers of the strong force. The advent of quantum chromodynamics led theorists to predict the existence of the odderon, C-odd gluonic compound. Proving its existence in high-energy collisions at Tevatron and LHC has been a major experimental challenge. The work is based on a model-independent analysis of data at medium-range momentum transfer. The TOTEM and D0 teams compared proton-proton data (recorded at collision energies of 2.76, 7, 8, and 13 TeV and extrapolated to 1.96 TeV), with Tevatron proton-antiproton data measured at 1.96 TeV. In agreement with theoretical predictions, the proton-proton cross-section exhibits a deeper dip and stays below the proton-antiproton cross-section until the bump region, thus evidence of odderon was found.

The differential cross-section of the top quark pair production via the quark-antiquark annihilation subprocess in hadron collision is calculated within the noncommutative standard model. A pure NC analytical expression for the forward-backward asymmetry at the tree level is obtained. Moreover, using recent Tevatron results from the full RUN2 data, a new lower bound on the noncommutative geometry parameter is deduced.

In this work, we present the calculation of the production cross sections of bottomonia states using Non-Relativistic Quantum Chromodynamics (NRQCD) formalism. The direct production cross-section of a resonance can be factorised in terms of short distance Quantum Chromodynamics (QCD) cross sections and long distance matrix elements (LDMEs) under NRQCD. We use a large set of measured ϒ(nS) production data at Tevatron and LHC energies in both central and forward rapidity regions to extract the LDMEs with better precision. The feed down contributions from the higher states including the χ b (3P) state are taken into account for the LDME extraction. The formalism provides a good description of the bottomonia data in wide transverse momentum range at different collision energies.

Single top quark production cross sections at hadron colliders are traditionally used to extract the modulus of the V tb element of the Cabibbo-Kobayashi-Maskawa matrix under the following assumption: |V tb | ≫ |V td |, |V ts |. For the first time, direct limits on |V td | and |V ts | are obtained using experimental data without the assumption of the unitarity of the CKM matrix. Limits on the |V td |, |V ts | and |V tb | are extracted from differential measurements of single top quark cross sections in t-channel as a function of the rapidity and transverse momentum of the top quark and the light jet recoiling against the top quark. We have shown that the pseudorapidity of the forward jet in the single top production is one of the most powerful observables for discriminating between the |V td | and |V tb | events. We perform a global fit of top quark related CKM elements to experimental data from the LHC Runs I and II and Tevatron. Experimental data include inclusive and differential single top cross sections in t-channel, inclusive tW production cross section, and top quark branching ratio to b quark and W boson. We present bounds on |V tb |, |V ts | and |V td | using current data and project the results for future LHC data sets corresponding to luminosities of 300 and 3000 fb−1.

We report on the first fully differential calculation of the next-to-next-to-leading-order (NNLO) QCD radiative corrections to the production of bottom-quark pairs at hadron colliders. The calculation is performed by using the $q_T$ subtraction formalism to handle and cancel infrared singularities in real and virtual contributions. The computation is implemented in the Matrix framework, thereby allowing us to efficiently compute arbitrary infrared-safe observables in the four-flavour scheme. We present selected predictions for bottom-quark production at the Tevatron and at the LHC at different collider energies, and we perform some comparisons with available experimental results. We find that the NNLO corrections are sizeable, typically of the order of $25$-$35\%$, and they lead to a significant reduction of the perturbative uncertainties. Therefore, their inclusion is crucial for an accurate theoretical description of this process., Comment: 31 pages, 4 tables, 13 figures; added references

$z$-Scaling of inclusive spectra as a manifestation of self-similarity and fractality of hadron interactions is illustrated. The scaling for negative particle production in $Au+Au$ collisions from BES-I program at RHIC is demonstrated. The scaling variable $z$ depends on the momentum fractions of the colliding objects carried by the interacting constituents, and on the momentum fractions of the fragmenting objects in the scattered and recoil directions carried by the inclusive particle and its counterpart, respectively. Structures of the colliding objects and fragmentation processes in final state are expressed by fractal dimensions. Medium produced in the collisions is described by a specific heat. The scaling function $\psi(z)$ reveals energy, angular, multiplicity, and flavor independence. It has a power behavior at high $z$ (high $p_T$). Based on the entropy principle and $z$-scaling, energy loss as a function of the collision energy, centrality and transverse momentum of inclusive particle is estimated. New conservation law including fractal dimensions is found. Quantization of fractal dimensions is discussed., Comment: 19 pages, 9 figures; Presented at the 40th International Conference on High Energy Physics, ICHEP2020

LHC $t\bar{t}$ data have the potential to provide constraints on the gluon distribution, especially at high $x$, with both ATLAS and CMS performing differential measurements. Recently, CMS has measured double-differential $t\bar{t}$ distributions at 8 TeV. In this paper we examine the impact of this data set on the gluon distribution. To that end we develop novel, double-differential NNLO predictions for that data. No significant impact is found when the CMS data is added to the CT14HERA2 global PDF fit, due to the larger impact of the inclusive jet data from both the Tevatron and the LHC. If the jet data are removed from the fit, then an impact is observed. If the CMS data is scaled by a larger weight, representing the greater statistical power of the jet data, a roughly equal impact on the gluon distribution is observed for the $t\bar{t}$ as for the inclusive jet data. For data samples with higher integrated luminosity at 13 TeV, a more significant impact of the double-differential $t\bar{t}$ data may be observed., Comment: 31 pages,22 figures, 6 tables

In recent years charm physics has undergone a renaissance, one which has been catalysed by an unexpected and impressive set of experimental results from the $B$-factories, the Tevatron and LHCb. The existence of $D^0\bar{D}{}^0$ oscillations is now well established, and the recent discovery of $CP$ violation in $D^0$ decays has further renewed interest in the charm sector. In this article we review the current status of charm-mixing and $CP$-violation measurements, and assess their agreement with theoretical predictions within the Standard Model and beyond. We look forward to the great improvements in experimental precision that can be expected over the coming two decades, and the prospects for corresponding advances in theoretical understanding., Article submitted to Vol. 71 of Annual Review of Nuclear and Particle Science

We study the Single-Parton-Scattering (SPS) production of double quarkonia (J/psi+J/psi, J/psi+Upsilon, and Upsilon+Upsilon) in pp and pp(bar) collisions at the LHC and the Tevatron as measured by the CMS, ATLAS, LHCb, and D0 experiments in the Colour-Evaporation Model (CEM), based on the quark-hadron-duality, including Next-to-Leading Order (NLO) QCD corrections up to alpha_s^5. To do so, we also perform the first true NLO --up to alpha_s^4-- study of the p_T-differential cross section for single-quarkonium production. This allows us to fix the non-perturbative CEM parameters at NLO accuracy in the region where quarkonium-pair data are measured. Our results show that the CEM at NLO in general significantly undershoots these experimental data and, in view of the other existing SPS studies, confirm the need for Double Parton Scattering (DPS) to account for the data. Our NLO study of single-quarkonium production at mid and large p_T also confirms the difficulty of the approach to account for the measured p_T spectra; this is reminiscent of the impossibility to fit single-quarkonium data with the sole 3S18 NRQCD contribution from gluon fragmentation. We stress that the discrepancy occurs in a kinematical region where the new features of the improved CEM are not relevant., LaTeX, 9 pages; 17 figures, 2 tables

As the heaviest known fundamental particle, the top quark ensures testing of the Standard Model and occupies a significant role in a lot of theories of new physics beyond the Standard Model. Up to now, the top quark has been only generated at the Tevatron and the Large Hadron Collider. However, one of the most important tasks of the physics program at the Large Hadron Collider is the investigation of the anomalous top quark interactions. In addition, the production of single top quarks, though rarer than production in pairs, presents us a different way to study the top quark produced via the electroweak interaction. This makes single top quark production an important signature for studying the properties of the top quark. Hence, we examine the anomalous $t\bar{t}\gamma$ interactions to investigate limits on the anomalous $a_A$ and $a_V$ couplings through single top quark production of the process $pp\rightarrow p \gamma^{*} p \rightarrow p t W X$ at the Large Hadron Collider, the High Luminosity Large Hadron Collider and High Energy Large Hadron Collider. The best limits obtained on the anomalous $a_A$ and $a_V$ couplings through the subprocess $\gamma^{*} b \rightarrow W t$ at the High Energy Large Hadron Collider with $L_{int}=15$ ab$^{-1}$ at $68\%$ Confidence Level are found to be $|a_{A}|=0.0590$ and $a_{V}=[-0.3202;0.0108]$. Therefore, we understand that $\gamma^{*} p$ collisions at the High Energy Large Hadron Collider improves the sensitivity limits of the anomalous coupling parameters according to previous studies., Comment: 22 pages, 9 figures and 10 tables. arXiv admin note: text overlap with arXiv:1906.09287

The central exclusive production of $\chi_{c}$ and $\chi_{b}$ at the LHC, RHIC and Tevatron energies is analyzed, using the recent unintegrated parton distribution (UGDs) functions available in the package TMDlib. Comparison with data is performed, which tests the underlying assumptions basing the theoretical approach and it can constrain the unintegrated gluon distribution function at the small-$x$ region. Predictions for LHC energies using recent UGDs based in CCFM formalism are provided. It is explored the underlying uncertainties on this production as the choice for the unintegrated gluon distribution and factorization scale is done. Moreover, based on the parton saturation model for the gluon distribution, analytical expressions for the rapidity distributions are proposed. The prompt production of $J/\psi+\gamma$ and $\Upsilon+\gamma$ is computed for the first time for LHC energies within the very same formalism used for $\chi$ production., Comment: 9 pages, 8 figures and 2 tables. Final version to be published in Physics Letters B

We calculate and compare the differential cross sections for forward $Z^0$-boson production at small transverse momentum, in proton-proton and proton-nucleus collisions, using both the collinear and dilute-dense factorization frameworks. In both cases, we implement a Sudakov resummation of the large logarithms generated by soft-gluon emissions, which is essential in order to describe the transverse momentum distribution of forward $Z^0$ bosons measured at the Tevatron and the LHC. We further compute the nuclear modification factor in the dilute-dense framework, hoping to single out signals of saturation effects at small values of $x$. Our predictions are compared with those obtained in the collinear factorization framework, using two different nuclear parton distribution functions., References added. Published version

Crystals were used at Fermilab accelerators for slow extraction and halo collimation in the Tevatron collider, and for channeling radiation generation experiments at the FAST electron linac facility. Here we overview past experience and major outcomes of these studies and discuss opportunities for new crystal acceleration R&D program.

Participation of a Joint Institute for Nuclear Research (JINR) team in the research program at the Tevatron at Fermilab is described. In their work on the upgraded CDF Run II detector, the emphasis was placed on top quark physics. The JINR team was fully engaged in the data analysis of the CDF experiment, particularly, in measuring the top quark mass in the dilepton and lepton–jet modes, in measuring the top quark charge, and in searching for the Higgs boson. The JINR team made a decisive contribution to the operation of the scintillation counter subsystem of the CDF muon trigger, to the trigger based on the vertex silicon detector for selection of events with secondary vertices and to the preshower detector of the electromagnetic calorimeter. The team was involved in the construction, upgrading, and operation of the system of scintillation counters and developed a system for the online monitoring of their parameters to ensure their effective operation in Run II. The work of the JINR researchers was highly appreciated by the international CDF collaboration.

The strong coupling constant α s ( M Z ) is determined using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Individual values of α s ( M Z ) are extracted from measurements of different experiments at several centre-of-mass energies, using QCD predictions complete in NNLO perturbation theory, supplemented with NNLL approximations to all orders, and suitable sets of parton distribution functions. These values are then combined using a likelyhood-based approach, with special emphasis on a consistent treatment of systemtic uncertainties and their correlations. The final combined result is α s ( M Z ) = 0.1177 − 0.0036 + 0.0034 .

In this paper, the results of investigation of single and pair production of J/ψ mesons in the D0 experiment at the Tevatron accelerator are considered. The contributions of single and double parton interactions to the total cross section of the pair production of J/ψ mesons are estimated for the first time. With the help of these measurements, the effective cross section of double parton interactions σeff was calculated.

In this paper, we give a brief review of recent theoretical studies of double prompt [Formula: see text] production at the FNAL Tevatron and the CERN LHC, to which both single- and double-parton-scattering processes contribute. In single parton scattering, we mainly present the results computed within the framework of non-relativistic quantum chromodynamics factorization combined with one of the two approaches to describe the parton inside the (anti)proton, the collinear parton model and the parton Reggeization approach. The contributions from double parton scattering calculated with different values of [Formula: see text] are also discussed. We conclude that, in double prompt [Formula: see text] hadroproduction, there remain some differences between theoretical predictions and experimental measurements.

This study is part of the RHIC program to probe properties of the Quark-Gluon Plasma medium properties using heavy quark energy loss. Part of the control of these measurements is to understand initial production of heavy quarks and how initial conditions in nucleus collisions can alter their yields. This manuscript reports the effort made by the PHENIX collaboration to measure total B-mesons yields, by looking at the fraction of muons from non-prompt J/ ψ decays at displaced vertices in p + p and Cu+Au collisions. The total cross-sections of b-quarks in 200 GeV and 510 GeV p + p collisions follow the increasing trend from fixed target experiments to high energy results from the Tevatron and the LHC. Integrated p T and centrality B-meson yields in Cu+Au integrated over transverse momentum and centrality are consistent with no nuclear modification or some enhancement, in contrast to prompt J/ ψ which shows a strong suppression.

We present new results of analysis of top-quark differential cross sections obtained by the CMS Collaboration in pp collisions in the framework of the z-scaling approach. The spectra are measured over a wide range of collision energy $$\sqrt s = 7,8,13TeV$$ and transverse momentum p T = 30−500 GeV/c of top-quark using leptonic and jet decay modes. Flavor independence of the scaling function ψ(z) is verified in the new kinematic range. The results of analysis of the top-quark spectra obtained at the LHC are compared with similar spectra measured in $$\overline p p$$ collisions at the Tevatron energy $$\sqrt s = 1.96TeV$$ . A tendency to saturation of ψ(z) for the process at low z and a power-law behavior of ψ(z) at high z is observed. The measurements of high-p T is observed. The measurements of highspectra of the top-quark production at highest LHC energy is of interest for verification of self-similarity of particle production, understanding flavor origin and search for new physics symmetries with top-quark probe.

In this paper I report on a measurement of the low-pT D+-meson production cross-section in proton-antiproton collisions at 1.96 TeV center-of-mass energy, using the full data set collected by the CDF experiment at the Tevatron collider during Run II. The measurement is performed in a yet unexplored low transverse momentum range, down to 1.5 GeV/c. The actual QCD theory cannot predict the behavior of the strong interactions in the low transferred-four-momentum region because in these kinematic conditions the strong coupling constant is of the order of the unity. Thus, a perturbative expansion is not useful. At present, several phenomenological models have been proposed, but they are able to describe only a few aspects of the observed physical quantities and not the full complexity. Experimental results in these conditions are then crucial to test new QCD models. The measurement of the differential cross section at low pT plays an important role in this context allowing refinement of current knowledge. While these results lie within the band of theoretical uncertainty, differences in shape suggest that theoretical predictions can benefit from further refinement taking account of them.

This article is an extended version of the talk is given at the IPAC19 (Melbourne, Australia, May 2019) on the occasion of acceptance of the ACFA/IPAC19 Nishikawa Tetsuji Prize for a recent, significant, original contribution to the accelerator field, with no age limit with citation ``\dots{}for original work on electron lenses in synchrotron colliders, outstanding contribution to the construction and operation of high-energy, high-luminosity hadron colliders and for tireless leadership in the accelerator community.''

We explore the sensitivity of Tevatron data to heavy new physics effects in differential dijet production rates using the SMEFT in light of the fact that consistent and conservative constraints from the LHC cannot cover relatively low cutoff scales in the EFT. In contrast to the results quoted by the experimental collaborations and other groups, we find that, once consistency of the perturbation expansion is enforced and reasonable estimates of theoretical errors induced by the SMEFT series in $\frac{E}{\Lambda}$ are included, there is no potential to constrain four-quark contact interactions using Tevatron data. This shows the general difficulty of constraining physics model-independently using fairly imprecise measurements, limited by low luminosity and/or systematic errors inherent to the precision of the detectors., Comment: 13 pages, 3 figures

The combination of the latest and most precise measurements of several top quark properties is presented in this paper in order to establish allowed regions on anomalous contributions to the Lorentz structure of the Wtb vertex. These measurements include single top production cross-sections, W boson helicity fractions and forward–backward asymmetries, both at Tevatron and at the Large Hadron Collider (LHC), up to a center-of-mass energy of 13 TeV. The results obtained at 95% Confidence Level (CL) for the top quark anomalous couplings are compared with the limits extracted from a combination that includes the expected measurements at the future High-Luminosity run of the LHC., The authors would like to thank the Center for The-oretical Physics of the Physics Department at the NewYork City College of Technology, City University of New York, for providing computing power from their High-Performance Computing Cluster. This work was sup-ported by the PSC-CUNY Award 61085-00 49 and by the contract SFRH/BSAB/139747/2018 from Fundação para a Ciência e Tecnologia (FCT)., info:eu-repo/semantics/publishedVersion

Measurements of the $W^\pm$ mass ($m_W$) provide an important consistency check of the Standard Model (SM) and constrain the possibility of physics beyond the SM. Precision measurements of $m_W$ at hadron colliders are inferred from kinematic distributions of transverse variables. We examine how this inference is modified when considering the presence of physics beyond the SM expressed in terms of local contact operators. We show that Tevatron measurements of $m_W$ using transverse variables are transparent and applicable as consistent constraints in the Standard Model Effective Field Theory (SMEFT) with small measurement bias. This means that the leading challenge to interpreting these measurements in the SMEFT is the pure theoretical uncertainty in how these measurements are mapped to Lagrangian parameters. We stress the need to avoid using naive combinations of Tevatron and LEPII measurements of $m_W$ without the introduction of any SMEFT theoretical error to avoid implicit UV assumptions. In a companion paper, we implement our procedure to consistently incorporate $m_W$ measurements into a global fit., 6pp, 4 figures V2: minor typo corrections and text clarifications, matches journal version

In high-energy processes, the predominant mechanism for b ¯ c bound states is the production of a high-energy b ¯ or c quark, which fragments into the b ¯ c state. An approximate approach for the evolution of the fragmentation functions for the production of the S-wave states of B c and B c ⁎ is presented using Laplace transform technique in the leading order (LO) and next-to-leading order (NLO) analyses. The cross sections, as a function of the transverse momentum for the direct hadro-production b ¯ ( c ) → B c and b ¯ ( c ) → B c ⁎ based on the nonrelativistic quantum chromodynamics (QCD) factorization, are determined and compared with the Large Hadron Collider (LHC) and Tevatron data at the 1S-wave state.

We report a selection of recent results from the Tevatron in QCD, B-Physics, Top, Higgs and Electroweak physics and searches for new phenomena. Among the most salient results, a new top mass from the Tevatron was released at this conference, with a precision of 0.64 GeV.

The mass of the top quark is a fundamental parameter of the standard model (SM) and has to be determined experimentally. In this talk, I present the most recent measurements of the top quark mass in $p\bar p$ collisions at $\sqrt s=1.96$~TeV recorded by the D0 experiment at the Fermilab Tevatron Collider. The measurements are performed in final states containing two leptons, using 5.4~\fb of integrated luminosity, and one lepton, using 9.7~\fb of integrated luminosity. The latter constitutes the most precise single measurement of the mass of the top quark, corresponding to a relative precision of 0.43\%. I conclude with a combination of our results with the results by the CDF collaboration, attaining a relative precision of 0.37\%, Comment: Proceedings for the ICHEP 2014 conference, Valencia

We present the combination of searches for the Standard Model Higgs boson at a center-of-mass energy of s = 1.96 TeV , using the full Run 2 dataset collected with the CDF and D0 detectors at the Fermilab Tevatron collider. We also present combined measurements of Higgs Boson production cross sections, branching ratios, and couplings to fermions and bosons. Finally, we present tests of different spin and parity hypotheses for a particle H of mass 125 GeV produced in association with a vector boson and decaying into a pair of b quarks, and place constraints on such hypotheses using the D0 data.

We consider the impact of the recent data obtained by the LHC, Tevatron, and fixed-target experiments on the nucleon quark distributions with a particular focus on disentangling different quark species. An improved determination of the poorly known strange sea distribution is obtained due to including data from the neutrino-induced deep-inelastic scattering experiments NOMAD and CHORUS. The impact of the associated (W + c) production data by CMS and ATLAS on the strange sea determination is also studied and a comparison with earlier results based on the collider data is discussed. Finally, the recent LHC and Tevatron data on the charged lepton asymmetry are compared to the NNLO ABM predictions and the potential of this input in improving the non-strange sea distributions is evaluated., Comment: Few typos fixed

Volume: 273 In this study we investigate the phenomenological viability of the Y = 0 Triplet Extended Supersymmetric Standard Model (TESSM) by comparing its predictions with the current Higgs data from ATLAS, CMS, and Tevatron, as well as the measured value of the B-S -> X-S gamma branching ratio. We scan numerically the parameter space for data points generating the measured particle mass spectrum and also satisfying current direct search constraints on new particles. We require all the couplings to be perturbative up to the scale A(UV) = 10(4) TeV, by running them with newly calculated two loop beta functions, and find that TESSM retains perturbativity as long as A, the triplet coupling to the two Higgs doublets, is smaller than 1.34 in absolute value. For vertical bar lambda vertical bar greater than or similar to 0.8 we show that the fine-tuning associated to each viable data point can be greatly reduced as compared to values attainable in MSSM. Finally, we perform a fit by taking into account 58 Higgs physics observables along with Br(B-s -> X-s gamma), for which we calculate the NLO prediction within TESSM. We find that, although naturality prefers a large vertical bar lambda vertical bar, the experimental data disfavors it compared to the small vertical bar lambda vertical bar region, because of the low energy observable Br(B-s -> X-s gamma).

The rich set of data collected from HERA, Tevatron and LHC collisions offer an extraordinary possibility to test different aspects of the perturbative Quantum Chromodynamics theory. A selection of recent results illustrates the variety and precision of these tests. The comparison of the experimental data with the most recent theoretical predictions allows to also appreciate the advances made in the theoretical field.

We present the most recent CDF measurements of single top quark production in proton-antiproton collisions, performed using the lepton plus jets and missing transverse energy plus jets final states. We also present the simultaneous measurements of single top quark production in s-channel and t-channel separately. The extraction of the CKM matrix element |Vtb| from the single top quark cross section is discussed as well. A recent analysis aimed at identifying the s-channel single top quark production is described and the evidence for this process is presented.

The mechanism of two-photon dilepton production is studied in the equivalent-photon (Weizsacker–Williams) approximation. This approximation is shown to describe well experimental data from hadron accelerators. The respective total and differential cross sections were obtained for the LHC and for the Tevatron collider at various energies of colliding hadrons. The differential cross sections were studied versus the dilepton invariant mass, transverse momentum, and emission angle in the reference frame comoving with the center of mass of colliding hadrons. The cases of semielastic and inelastic collisions were examined.

We present the Q2-evolution of the intrinsic heavy quark distribution by non-singlet evolution equation. This technique allows us to evolve intrinsic heavy quark distribution independently from the gluon and other PDFs. We use this feature to investigate the impact of intrinsic charm contribution for prediction of production γ+c-jet in the pp collision at the LHC. Also we compare the result of pp‾→γ+c-jet with the experimental data provided by the Tevatron collider.

The universality of free fall, the weak equivalence principle (WEP), is a cornerstone of the general theory of relativity, the most precise theory of gravity confirmed in all experiments up to date. The WEP states the equivalence of the inertial, $m$, and gravitational, $m_g$, masses and was tested in numerous occasions with normal matter at relatively low energies. However, there is no proof for the matter and antimatter at high energies. For the antimatter the situation is even less clear -- current direct observations of trapped antihydrogen suggest the limits $-65 < m_g / m < 110$ not excluding the so-called antigravity phenomenon, i.e. repulsion of the antimatter by Earth. Here we demonstrate an indirect bound $0.96 < m_g/m < 1.04$ on the gravitational mass of relativistic electrons and positrons coming from the absence of the vacuum Cherenkov radiation at the Large Electron-Positron Collider (LEP) and stability of photons at the Tevatron collider in presence of the annual variations of the solar gravitational potential. Our result clearly rules out the speculated antigravity. By considering the absolute potential of the Local Supercluster (LS), we also predict the bounds $1 - 4\times 10^{-7} < m_g/m < 1 + 2\times 10^{-7}$ for an electron and positron. Finally, we comment on a possibility of performing complementary tests at the future International Linear Collider (ILC) and Compact Linear Collider (CLIC)., 6 pages. Version accepted for publication in Phys. Lett. B

We present the derivation of the NNLO two-parton final state contributions to top pair production in the quark-antiquark channel proportionnal to the leading colour factor N c 2 . Together with the three and four-parton NNLO contributions presented in a previous publication, this enables us to complete the phenomenologically most important NNLO corrections to top pair hadro-production in this channel. We derive this two-parton contribution using the massive extension of the NNLO antenna subtraction formalism and implement those corrections in a parton-level event generator providing full kinematical information on all final state particles. In addition, we also derive the heavy quark contributions proportional to N h . Combining the new leading-colour and heavy quark contributions together with the light quark contributions derived previously, we present NNLO differential distributions for LHC and Tevatron. We also compute the differential top quark forward-backward asymmetry at Tevatron and find that our results are in good agreement with the measurements by the D0 collaboration., Journal of High Energy Physics, 2015 (12), ISSN:1126-6708, ISSN:1029-8479

a b s t r a c t We demonstrate that the recent studies of J /ψ-pair production by CMS at the LHC and by D0 at the Tevatron reveal the presence of different production mechanisms in different kinematical regions. We find out that next-to-leading-order single parton scattering contributions at α 5 s dominate the yield at large transverse momenta of the pair. Our analysis further emphasises the importance of double parton scatterings - which are expected to dominate the yield at large J /ψ-rapidity differences - at large invariant masses of the pair in the CMS acceptance, and thereby solve a large discrepancy between the theory and the CMS data. In addition, we provide the first exact - gauge-invariant and infrared-safe - evaluation of a class of leading-P T (P − 4 T ) next-to-next-to-leading-order contributions at α 6 s , which can be relevant in the region of large values of P T min = min(P T 1, P T 2). Finally, we derive simple relations for the feed-down fractions from the production of an excited charmonium state with a J /ψ in the case of the dominance of the double parton scatterings, which significantly deviate from those for single parton scatterings. Such relations can be used to discriminate these extreme scenarios, either DPS or SPS

We present a review of the recent theoretical and experimental developments related to the field of diffraction, parton saturation, and forward physics. We first discuss our present understanding of the proton structure in terms of quarks and gluons, the degrees of freedom of quantum chromodynamics. We then focus on some of the main results on diffraction at the HERA electron–proton collider in DESY, Germany, at the Tevatron proton–antiproton collider at Fermilab, Batavia, US, and at the CERN Large Hadron Collider (LHC) proton–proton and nucleus–nucleus collider, which is located in Geneva, Switzerland. We also present a selected amount of results on diffraction and photon exchanges that can be done at the LHC experiments and at a future Electron Ion Collider (EIC) to be built in the US at Brookhaven National Laboratory, New York.

The statistical event-by-event analysis of inelastic interactions of protons in emulsion at 800 GeV reveals the existence of group of events with Gaussian pseudorapidity distributions for produced particles, as suggested by hydrodynamic-tube model. Events belong to very central collisions of protons with heavy emulsion nuclei with probability of realization of less than 1% and with multiplicity of shower particles exceeding (2-3 times) the average multiplicity in proton-nucleus collisions in emulsion. Bjorken’s energy density for these events reaches 2.0 GeV per fm3. The data are interpreted as a result of the QCD phase transition in proton-tube collisions at Tevatron energies.

We study the sensitivity to physics beyond the standard model of precise top-quark pair production measurements at future lepton colliders. A global effective-field-theory approach is employed, including all dimension-six operators of the Warsaw basis which involve a top-quark and give rise to tree-level amplitudes that interfere with standard-model $e^+e^-\to t\,\bar t\to bW^+\bar bW^-$ ones in the limit of vanishing $b$-quark mass. Four-fermion and CP-violating contributions are taken into account. Circular-collider-, ILC- and CLIC-like benchmark run scenarios are examined. We compare the constraining power of various observables to a set of statistically optimal ones which maximally exploit the information contained in the fully differential $bW^+\bar bW^-$ distribution. The enhanced sensitivity gained on the linear contributions of dimension-six operators leads to bounds that are insensitive to quadratic ones. Even with statistically optimal observables, two centre-of-mass energies are required for constraining simultaneously two- and four-fermion operators. The impact of the centre-of-mass energy lever arm is discussed, that of beam polarization as well. A realistic estimate of the precision that can be achieved in ILC- and CLIC-like operating scenarios yields individual limits on the electroweak couplings of the top quark that are one to three orders of magnitude better than constraints set with Tevatron and LHC run I data, and three to two hundred times better than the most optimistic projections made for the high-luminosity phase of the LHC. Clean global constraints can moreover be obtained at lepton colliders, robustly covering the multidimensional effective-field-theory space with minimal model dependence., Comment: 6 appendices, 66 pages, 37 figures, 10 tables, codes and numerics at https://github.com/gdurieux/optimal_observables_ee2tt2bwbw

We consider the transverse-momentum ($q_T$) distribution of $Z$ bosons produced in hadronic collisions. At small values of $q_T$, we perform the analytic resummation of the logarithmically enhanced QED contributions up to next-to-leading logarithmic accuracy, including the mixed QCD-QED contributions at leading logarithmic accuracy. Resummed results are consistently matched with the next-to-leading fixed-order results (i.e. $\mathcal{O}(\alpha^2)$) at small, intermediate and large values of $q_T$. We combine the QED corrections with the known QCD results at next-to-next-to-leading order ($\mathcal{O}(\alpha_S^2)$) and next-to-next-to-leading logarithmic accuracy. We show numerical results at LHC and Tevatron energies, studying the impact of the QED corrections and providing an estimate of the corresponding perturbative uncertainty. Our analytic results for the combined QED and QCD resummation, obtained through an extension of the $q_T$ resummation formalism in QCD, are valid for the production of generic neutral and colourless high-mass systems in hadronic collision., Comment: 13 pages, 3 figures

With the Higgs search program already quite mature, there is the exciting possibility of discovering a new particle with rates near that of the SM Higgs. We consider models with a signal in $\gamma \gamma$ below the SM Higgs mass, taking the recent $2.9\, \sigma$ (local) CMS excess at 95 GeV as a target. We discuss singlet models with additional vectorlike matter, but argue that a Type-I two Higgs doublet model provides a more economical scenario. In such a setup, going into regions of moderate-to-strong fermiophobia, the enhanced $\gamma \gamma$ branching ratio allows signals from $VH$+VBF production to yield $\sigma \times BR_{\gamma\gamma} $ comparable to total SM rates. Light $H$ production can be dominated via rare top decays $t \rightarrow b H^+ \rightarrow b W^{*} H$, which provides an alternate explanation of the excess. We consider this in the context of other Higgs anomalies, namely the LEP Higgs excess near the same mass, and excesses in $t\bar{t}h$ searches at Tevatron and LHC. We find that with $140\, \mathrm{GeV} < m_{H^+} < 160\, \mathrm{GeV}$, $\tan \beta \sim 5$ and a coupling to gauge bosons of $\sin^2 \delta \sim 0.1$, such a scenario can produce all the excesses simultanously, where $tth$ arise from contamination from the rare top decays, as previously proposed. An implication of the Type-I scenario is that any $\gamma \gamma$ excess should be associated with additional elements that could reduce background, including $b$-jets, forward jets or signs of vector boson production., Comment: 15 pages, 3 figures

Physics letters / B 782, 362 - 366 (2018). doi:10.1016/j.physletb.2018.05.054, We present the matching relations of the variable flavor number scheme at next-to-leading order, which are of importance to define heavy quark partonic distributions for the use at high energy colliders such as Tevatron and the LHC. The consideration of the two-mass effects due to both charm and bottom quarks, having rather similar masses, are important. These effects have not been considered in previous investigations. Numerical results are presented for a wide range of scales. We also present the corresponding contributions to the structure function $F_{2}(x,Q^{2})$., Published by Elsevier, Amsterdam

The top quark is the heaviest known elementary particle, and it is often seen as a window to search for new physics processes in particle physics. A large program to study the top-quark properties has been performed both at the Tevatron and LHC colliders by the D0, CDF, ATLAS and CMS experiments. The most recent results are discussed in this review., 38 pages, 8 figures, published in Annual Reviews

I review calculations of soft-gluon corrections for top-quark production in hadron collisions. I describe theoretical formalisms for their resummation and for finite-order expansions. I show that soft-gluon corrections are dominant for a large number of top-quark processes. I discuss top-antitop pair production as well as single-top production, including total cross sections and differential distributions, and compare with data from the LHC and the Tevatron. I also discuss top-quark production in association with charged Higgs bosons, $Z$ bosons, and other particles in models of new physics., Comment: 37 pages, 31 figures

Recent measurements of top quark pair production cross section, which is performed at the LHC and the Tevatron collider, are studied using Hessian profiling technique to obtain their impact on the parton distribution functions (PDFs). The top quark production data covers different center-of-mass energies $\sqrt{s}$= 1.96, 5.02, 7, 8 and 13 TeV in either $pp$ or $p\bar{p}$ collisions. It is explained how the Hessian profiling method may be used to assess the impact of these new data on PDFs and consequently on their predictions. In this research, the impact of recent measurements of top quark pair cross sections on different CT14, MMHT2014, and NNPDF3.0 PDF sets is investigated. The analysis results show that the recent top quark production at the LHC and Tevatron data provide significant constraints in particular on the central value, relative uncertainties or both for the $s$-quark distribution and the gluon PDFs in both of CT14, MMHT2014 PDF sets and are insensitive to valence quark PDFs. A small constraint on the $\bar u$- sea quark distribution for CT14 PDF is also observed. There is no impact on the NNPDF3.0 PDF set in presence of these data., Comment: 22 pages, 9 figures, 4 tables

We investigate the bounds which can be placed on generic new-physics contributions to dijet production at the LHC using the framework of the Standard Model Effective Field Theory, deriving the first consistently-treated EFT bounds from non-resonant high-energy data. We recast an analysis searching for quark compositeness, equivalent to treating the SM with one higher-dimensional operator as a complete UV model. In order to reach consistent, model-independent EFT conclusions, it is necessary to truncate the EFT effects consistently at order $1/\Lambda^2$ and to include the possibility of multiple operators simultaneously contributing to the observables, neither of which has been done in previous searches of this nature. Furthermore, it is important to give consistent error estimates for the theoretical predictions of the signal model, particularly in the region of phase space where the probed energy is approaching the cutoff scale of the EFT. There are two linear combinations of operators which contribute to dijet production in the SMEFT with distinct angular behavior; we identify those linear combinations and determine the ability of LHC searches to constrain them simultaneously. Consistently treating the EFT generically leads to weakened bounds on new-physics parameters. These constraints will be a useful input to future global analyses in the SMEFT framework, and the techniques used here to consistently search for EFT effects are directly applicable to other off-resonance signals., Comment: v1: 23 pages, 9 figures, 3 tables; v2: references added, typos corrected, matches version published in JHEP

In this article, we demonstrate that the unexpected peak at around $95 \, {\rm GeV}$ as seen recently by CMS in the di-photon final state can be explained within the type-I~two-Higgs-doublet model by means of a moderately-to-strongly fermiophobic CP-even Higgs $H$. Depending on the Higgs mass spectrum, the production of such~a~$H$ arises dominantly from vector boson fusion or through a cascade in either $pp \to t \bar t$ with $\overset{(-)}{t} \to H^{\pm} \overset{(-)}{b} \to W^{\pm \, \ast} H \overset{(-)}{b}$ or $pp \to A$ with $A \to W^{\mp} H^{\pm} \to W^{\mp} W^{\pm} H$ or via $pp \to W^{\pm \, \ast} \to H^\pm H$. In this context, we also discuss other Higgs anomalies such as the LEP excess in Higgsstrahlung and the observation of enhanced rates in $t \bar t h$ at both the Tevatron and the LHC, showing that parameters capable of explaining the CMS di-photon signal can address the latter deviations as well. The Higgs spectra that we explore comprise masses between $80 \, {\rm GeV}$ and $350\, {\rm GeV}$. While at present all constraints from direct and indirect searches for spin-0 resonances can be shown to be satisfied for such light Higgses, future LHC data will be able to probe the parameter space that leads to a simultaneous explanation of the discussed anomalies., 21 pages, 14 figures; v3: matches version published in JHEP

We calculate the full one-loop electroweak radiative corrections, of ${\cal O}(\alpha^2\alpha_s)$, to the cross section of single $Z$-boson inclusive hadroproduction at finite transverse momentum ($p_T$). This includes the ${\cal O}(\alpha)$ corrections to $Z+j$ production, the ${\cal O}(\alpha_s)$ corrections to $Z+\gamma$ production, and certain QCD-electroweak interference contributions involving a single quark trace. We recover the QCD and purely weak corrections and study the QED corrections and the QCD-electroweak interference contributions for the first time. We also consider direct and resolved photoproduction in elastic and inelastic scattering. We present $p_T$ and rapidity distributions for the experimental conditions at the Fermilab Tevatron and the CERN LHC and assess the significance of the various contributions., Comment: 31 pages, 11 figures; discussion enhanced, figures added, references added and updated; accepted for publication in Nucl. Phys. B