scholarly journals Exclusive dilepton production at forward rapidities in PbPb collisions

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
V. P. Goncalves ◽  
D. E. Martins ◽  
M. S. Rangel
Keyword(s):  
Cross Sections ◽  
Experimental Analysis ◽  
Lhcb Collaboration ◽  
Leptonic Decay ◽  
Dilepton Production ◽  
Decay Channels ◽  
Diffractive Production ◽  
Bsm Physics ◽  
Exclusive Processes

AbstractThe dilepton production at forward rapidities in diffractive and exclusive processes present in ultraperipheral PbPb collisions at the LHC is investigated. Predictions for the $$e^+ e^-$$ e + e - , $$\mu ^+ \mu ^-$$ μ + μ - and $$\tau ^+ \tau ^-$$ τ + τ - cross sections are presented taking into account of realistic cuts that can be implemented by the LHCb Collaboration in a future experimental analysis. Our results indicate that the background associated with the diffractive production can be strongly suppressed and the exclusive processes can be cleanly separated. For the $$\tau ^+ \tau ^-$$ τ + τ - production, the semi and purely leptonic decay channels are considered. Our results indicate that a future experimental analysis of the dilepton production at the LHCb is feasible and can be useful to search for BSM physics.

scholarly journals RESTRICTED LOCALITY OF QUARK-HADRON DUALITY IN EXCLUSIVE MESON PHOTOPRODUCTION REACTIONS ABOVE THE RESONANCE REGION

2005 ◽  
Vol 20 (08n09) ◽  
pp. 1910-1913 ◽  
Author(s):  
QIANG ZHAO ◽  
FRANK E. CLOSE
Keyword(s):  
Cross Sections ◽  
Differential Cross ◽  
Scaling Laws ◽  
Resonance Region ◽  
Meson Photoproduction ◽  
Counting Rule ◽  
Dimensional Scaling ◽  
Exclusive Processes ◽  
Photoproduction Reactions ◽  
Hadron Duality

We show how deviations from the dimensional scaling laws for exclusive processes may be related to a breakdown in the locality of quark-hadron duality, i.e. the "restricted locality". For exclusive reactions like meson photo- and electroproduction above the resonance region, we explore the effects arising from such a local duality breaking and propose that it can be a possible source for oscillations about the smooth quark counting rule predicted by pQCD in the 90-degree differential cross sections.

Searching for the doubly charged scalars in the Georgi–Machacek model via γγ collisions at the ILC

2018 ◽  
Vol 33 (11) ◽  
pp. 1841003
Author(s):  
Jun Cao ◽  
Yu-Qi Li ◽  
Yao-Bei Liu
Keyword(s):  
Cross Sections ◽  
Linear Collider ◽  
Coupling Parameter ◽  
Production Cross ◽  
International Linear Collider ◽  
Scalar Coupling ◽  
Decay Channels ◽  
Decay Modes ◽  
The Future ◽  
Doubly Charged

The Georgi–Machacek (GM) model predicts the existence of the doubly-charged scalars [Formula: see text], which can be seen the typical particles in this model and their diboson decay channels are one of the most promising ways to discover such new doubly-charged scalars. Based on the constraints of the latest combined ATLAS and CMS Higgs boson diphoton signal strength data at [Formula: see text] confidence level, we focus on the study of the triple scalar production in [Formula: see text] collisions at the future International Linear collider (ILC): [Formula: see text], where the production cross-sections are very sensitive to the triple scalar coupling parameter [Formula: see text]. Considering the typical same-sign diboson decay modes for the doubly-charged scalars, the possible final signals might be detected via this process at the future ILC experiments.

scholarly journals Measurements of the CP-violating phase ϕs at LHCb

2018 ◽  
Vol 182 ◽  
pp. 02009
Author(s):  
Varvara Batozskaya
Keyword(s):  
Mass Region ◽  
Lhcb Collaboration ◽  
Data Set ◽  
Decay Channels ◽  
Lhcb Experiment

The measurement of the mixing-induced CP-violating phase ϕs in the B0s - B0s system is one of the key goals of the LHCb experiment. It has been measured at the LHCb collaboration exploiting the Run I data set and using several decay channels. In particular, the most recent Run I result has been obtained analyzing B0s → J/ψK+K- candidates in the mass region above the ϕ(1020) resonance. Despite the large improvements in the sensitivity of ϕs during the last decade, the precision is still limited by the available statistics.

DILEPTON PRODUCTION STUDIED WITH THE HADES SPECTROMETER

2011 ◽  
Vol 26 (03n04) ◽  
pp. 384-389 ◽  
Author(s):  
◽  
A. RUSTAMOV ◽  
G. AGAKISHIEV ◽  
A. BALANDA ◽  
D. BELVER ◽  
...  
Keyword(s):  
Cross Sections ◽  
Beam Energy ◽  
Decay Channel ◽  
Production Cross ◽  
State Density ◽  
Vector Mesons ◽  
Dilepton Production ◽  
Neutral Pions ◽  
Nuclear Ground State ◽  
Medium Mass

With the HADES spectrometer at GSI we have studied dilepton production in various collision systems from elementary N + N , over p + A , up to the medium-heavy Ar + KCl system. We have confirmed the puzzling results of the former DLS collaboration at the Bevalac. While we have traced the origin of the excess pair yield in C + C collisions to elementary p + p and n + p processes, we find a significant contribution from the dense phase of the collision in larger Ar + KCl system. From recently obtained e + e - pair spectra in p + p and p + Nb interactions at 3.5 GeV kinetic beam energy the inclusive production cross sections for neutral pions, η , ω and ρ mesons are extracted for the first time at this beam energy. Furthermore, the production mechanisms of the vector mesons, which are not known at these energies, are investigated. The direct comparison of p + p and p + Nb data allows us to investigate in-medium mass modifications of vector mesons at nuclear ground state density. On the other hand, exclusive production of ω and η mesons in p + p reactions at 3.5 GeV were studied via their π+π-π0 decay channel. Production cross sections and angular distributions for both states were determined.

scholarly journals CHARGED PION PHOTOPRODUCTION FROM HYDROGEN AND DEUTERIUM AT JEFFERSON LAB

2003 ◽  
Vol 18 (02n06) ◽  
pp. 215-224
Author(s):  
◽  
HAIYAN GAO
Keyword(s):  
Cross Sections ◽  
Degrees Of Freedom ◽  
Charged Pion ◽  
Center Of Mass ◽  
Oscillatory Behavior ◽  
Color Transparency ◽  
Jefferson Lab ◽  
Glauber Theory ◽  
Nuclear Dependence ◽  
Exclusive Processes

The γn → π-p and γp → π+n reactions are essential probes of the transition from meson-nucleon degrees of freedom to quark-gluon degrees of feedom in exclusive processes. The cross sections of these processes are also, advantageous, for the investigation of oscillatory behavior around the quark counting prediction, since they decrease relatively slower with energy compared with other photon-induced processes. Moreover, these photoreactions in nuclei can probe the QCD nuclear filtering and color transparency effects. In this talk, I discuss the preliminary results on the γp → π+n and γn → π-p processes at a center-of-mass angle of 90° from Jefferson Lab experiment E94-104. I also discuss a new experiment in which singles γp → π+n measurement from hydrogen, and coincidence γn → π-p measurements at the quasifree kinematics from deuterium and 12 C for photon energies between 2.25 GeV to 5.8 GeV in fine steps at a center-of-mass angle of 90° are planned. The proposed measurement will allow a detailed investigation of the oscillatory scaling behavior in photopion production processes and the study of the nuclear dependence of rather mysterious oscillations with energy that previous experiments have indicated. The various nuclear and perturbative QCD approaches, ranging from Glauber theory, to quark-counting, to Sudakov-corrected independent scattering, make dramatically different predictions for the experimental outcomes.

scholarly journals Study on the anomalous quartic $$W^+W^-\gamma \gamma $$ couplings of electroweak bosons in $$e^-p$$ collisions at the LHeC and the FCC-he

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
A. Gutiérrez-Rodríguez ◽  
M. A. Hernández-Ruíz ◽  
E. Gurkanli ◽  
V. Ari ◽  
M. Köksal
Keyword(s):  
Cross Sections ◽  
Production Cross ◽  
Hadronic Decay ◽  
Production Mode ◽  
Decay Channels ◽  
The Future

AbstractIn this paper, a study is carried out on the $$e^-p \rightarrow e^-\gamma ^* p \rightarrow p W^-\gamma \nu _e$$ e - p → e - γ ∗ p → p W - γ ν e production to probe quartic $$W^+W^-\gamma \gamma $$ W + W - γ γ couplings at the Large Hadron electron Collider (LHeC) with $$\sqrt{s}= 1.30, 1.98\,\hbox {TeV}$$ s = 1.30 , 1.98 TeV and at the Future Circular Collider-hadron electron (FCC-he) with $$\sqrt{s}= 3.46, 5.29\,\hbox {TeV}$$ s = 3.46 , 5.29 TeV . Production cross-sections are determined for both at leptonic and hadronic decay channels of the W-boson. With the data from future $$e^-p$$ e - p colliders, it is possible to obtain sensitivity measures at $$95\%$$ 95 % C.L. on the anomalous $$f_ {M,i}/\Lambda ^4$$ f M , i / Λ 4 and $$ f_ {T,j}/\Lambda ^4$$ f T , j / Λ 4 couplings which are competitive with the limits obtained by the LHC, as well as with others limits reported in the literature. The production mode $$e^-p \rightarrow e^-\gamma ^* p \rightarrow p W^-\gamma \nu _e $$ e - p → e - γ ∗ p → p W - γ ν e in $$e^-p$$ e - p collisions offers a window for study the quartic $$W^+W^-\gamma \gamma $$ W + W - γ γ electroweak bosons couplings at the LHeC and the FCC-he, which provides a much cleaner collision environment than the LHC.

scholarly journals Synthesis on Heavy Higgs from the Standard Model to 2HDM and Beyond

2020 ◽  
Vol 18 ◽  
pp. 110-142
Author(s):  
Abdeljalil Habjia
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Cross Sections ◽  
Particle Physics ◽  
Hadron Collider ◽  
Signal Strength ◽  
Beyond The Standard Model ◽  
Decay Channels ◽  
Higgs Decay ◽  
The Standard Model

In the context of particle physics, within the ATLAS and CMS experiments at large hadron collider (LHC), this work presents the discussion of the discovery of a particle compatible with the Higgs boson by the combination of several decay channels, with a mass of the order of 125.5 GeV. With increased statistics, that is the full set of data collected by the ATLAS and CMS experiments at LHC ( s1/2 = 7GeV and s1/2 = 8GeV ), the particle is also discovered individually in the channel h-->γγ with an observed significance of 5.2σ and 4.7σ, respectively. The analysis dedicated to the measurement of the mass mh and signal strength μ which is defined as the ratio of σ(pp --> h) X Br(h-->X) normalized to its Standard Model where X = WW*; ZZ*; γγ ; gg; ff. The combined results in h-->γγ channel gave the measurements: mh = 125:36 ± 0:37Gev, (μ = 1:17 ± 0:3) and the constraint on the width Γ(h) of the Higgs decay of 4.07 MeV at 95%CL. The spin study rejects the hypothesis of spin 2 at 99 %CL. The odd parity (spin parity 0- state) is excluded at more than 98%CL. Within the theoretical and experimental uncertainties accessible at the time of the analysis, all results: channels showing the excess with respect to the background-only hypothesis, measured mass and signal strength, couplings, quantum numbers (JPC), production modes, total and differential cross-sections, are compatible with the Standard Model Higgs boson at 95%CL. Although the Standard Model is one of the theories that have experienced the greatest number of successes to date, it is imperfect. The inability of this model to describe certain phenomena seems to suggest that it is only an approximation of a more general theory. Models beyond the Standard Model, such as 2HDM, MSSM or NMSSM, can compensate some of its limitations and postulate the existence of additional Higgs bosons.

scholarly journals NLO QCD corrections to exclusive quarkonium-pair production in photon–photon collision

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Hao Yang ◽  
Zi-Qiang Chen ◽  
Cong-Feng Qiao
Keyword(s):  
Pair Production ◽  
Cross Sections ◽  
Linear Collider ◽  
International Linear Collider ◽  
Leading Order ◽  
Numerical Result ◽  
Electron Positron ◽  
Belle Ii ◽  
Exclusive Processes ◽  
Photon Collision

AbstractWe calculate the next-to-leading order (NLO) quantum chromodynamics (QCD) corrections to the exclusive processes $$\gamma +\gamma \rightarrow {\mathcal {Q}}+{\mathcal {Q}}$$ γ + γ → Q + Q , with $${\mathcal {Q}}=J/\psi ,\ \eta _c,\ \Upsilon $$ Q = J / ψ , η c , Υ , or $$\eta _b$$ η b , in the framework of non-relativistic QCD (NRQCD) factorization formalism. The cross sections at the SuperKEKB electron–positron collider, as well as at the future colliders, like the circular electron positron collider (CEPC) and the international linear collider (ILC), are evaluated. Numerical result indicates that the processes for $$J/\psi $$ J / ψ -pair production and $$\eta _c$$ η c -pair production are hopefully observable at the Belle II detector within the next decade.

scholarly journals On the pair correlations of neutral K, D, B and Bs mesons with close momenta produced in inclusive multiparticle processes

2019 ◽  
Vol 204 ◽  
pp. 06007
Author(s):  
Valery V. Lyuboshitz ◽  
Vladimir L. Lyuboshitz
Keyword(s):  
Cross Sections ◽  
Correlation Functions ◽  
Final State Interaction ◽  
Additional Contribution ◽  
Final State ◽  
Pair Correlations ◽  
Decay Channels ◽  
Neutral Kaons ◽  
The Difference ◽  
Inclusive Processes

The phenomenological structure of inclusive cross-sections of the production of two neutral K mesons in hadron–hadron, hadron–nucleus and nucleus–nucleus collisions is theoretically investigated taking into account the strangeness conservation in strong and electromagnetic interactions. Relations describing the dependence of the correlations of two short-lived and two long-lived neutral kaons $K_S^0K_S^0,K_L^0K_L^0$ and the correlations of “mixed” pairs $K_S^0K_L^0$ at small relative momenta upon the space-time parameters of the generation region of K0 and K̅0 mesons have been obtained. These relations involve the contributions of Bose-statistics and S -wave strong final-state interaction of two K0 (K̅0) mesons as well as of the K0 and K̅0 mesons, and also the additional contribution of transitions K+K– → K0 K̅0, and they depend upon the relative fractions of generated pairs K0K0, K̅0 K̅0 and K0 K̅0. It is shown that under the strangeness conservation the correlation functions of the pairs $K_S^0K_S^0$ and $K_L^0K_L^0$, produced in the same inclusive process, coincide, and the difference between the correlation functions of the pairs $K_S^0K_S^0$ and $K_S^0K_L^0$ is conditioned exclusively by the production of the pairs of non-identical neutral kaons K0 K̅0. For comparison, analogous correlations for the pairs of neutral heavy mesons D0, B0 and $B_s^0$, generated in multiple inclusive processes with charm (beauty) conservation, are also theoretically analyzed. These correlations are described by quite similar expressions: in particular, just as for K0 mesons, the correlation functions for the pairs of states with the same CP parity (RS S = RLL) and with different CP parity (RS L) do not coincide, and the difference between them is conditioned exclusively by the production of pairs D0 D̅0, B0B̅0 and $B_s^0\bar B_s^0$. However, contrary to the case of K0 mesons, here the distinction of CP-even and CP-odd states encounters difficulties – due to the insignificant differences of their lifetimes and the relatively small probability of purely CP-even and CP-odd decay channels. Nevertheless, one may hope that it will become possible at future colliders.

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