V. A. Khoze, J. W. Lamsa, R. Orava, M. G. Ryskin
Photon bremsstrahlung is proposed to be used to identify elastic proton-proton interactions at the LHC. In addition to a measurement of the elastic pp cross section (assuming that the elastic slope is known), the bremsstrahlung photons will allow the evaluation of the total pp cross section, luminosity and to align the Zero Degree Calorimeters (ZDCs).
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We consider the first LHC data for elastic pp scattering in the framework of Regge theory with multiple Pomeron exchanges. The simplest eikonal approach allows one to describe differential elastic cross sections at LHC, as well as pp and $\bar{p}p$ scattering at lower collider energies, on a reasonable level.
The first data from the TOTEM experiment agree well with Regge theory, and demand a hard-pomeron contribution.
We discuss the role of the impact--parameter dependent quantities. Their use along with the available experimental data on elastic scattering at the LHC could serve for an additional insight into the asymptotics.
We study high energy $\small{\rm{pp}}$ and $\small{\rm{\bar {p}p}}$ elastic scattering in the TeV region based on an effective field theory model of the proton. We phenomenologically investigate the main processes underlying elastic scattering and quantitatively describe the measured elastic d$\smallσ$/dt at energies 7.0 TeV (LHC $\small{\rm{pp}}$), 1.96 TeV (Tevatron $\small{\rm{\bar {p}p}}$), and 0.630 TeV (SPS $\small{\rm{\bar {p}p}}$). Finally, we give our prediction for $\small{\rm{pp}}$ elastic d$\smallσ$/dt at 14 TeV that will be measured by the TOTEM Collaboration.
The soft diffraction phenomena in the elastic proton-proton scattering are reviewed from the viewpoint of experiments at the LHC (TOTEM and ATLAS collaboration). In the framework of the High Energy Generalized Structure (HEGS) model the form of the diffraction minimum in the nucleon-nucleon elastic scattering in a wide energy region is analyzed. The energy dependences of the main characteristics of the diffraction dip are obtained. The numerical predictions at LHC energies are presented. The comparison of the model predictions with the new LHC data at $\sqrt{s}=13$ TeV is made.
It is shown that the darkness of the interaction region of protons is governed by the ratio of the slope of the diffraction cone to the total cross section. At LHC energies, it becomes completely absorptive at small impact parameters. The lower limit of the ratio is determined. That imposes some restrictions on its energy behavior. It is argued that the black disk terminology should be replaced by the black torus.
The model of elastic scattering amplitudes dominated by the triple (at $t=0$) pomeron pole suggested earlier is modified to confront to existing experimental data on $pp$ and $\bar pp$ total and differential cross sections at $\sqrt{s}\geq 19$ GeV and $|t|\leq 14.2$ GeV$^{2}$ including the newest TOTEM data. Predictions for the future TOTEM measurements at 13 and 14 TeV are given.
In this paper we show that the excess of the tau tau events with respect to the Standard Model background predictions, observed by the ATLAS and CMS collaborations and interpreted as the evidence of the Higgs-boson decay into a pair of tau-leptons, may be accounted for by properly taking into account QED radiative corrections in the modelling of the Z/gamma* -> tau tau background.
The measurements of high energy \bar p p and pp elastic at ISR, SPS and Tevatron colliders have provided usefull informations on the behavior of the scattering amplitude. A large step in energy domain is accomplished with the LHC collider presently running, giving a unique opportunity to improve our knowledge on the asymptotic regime of the elastic scattering amplitude and to verify the validity of our theoretical approach, to describe the total cross section σ_{tot}(s), the total elastic cross section σ_{el}(s), the ratio of the real to imaginary parts of the forward amplitude ρ(s) and the di…
Diffraction and elastic scattering at the LHC
本文综述 ATLAS、CMS 和 LHCb 利用前向探测与完整质子测量，在弹性散射、衍射、jet-gap-jet 及总截面参数方面的最新结果。
We present a detailed numerical study of lepton-pair production via the Drell-Yan process above the Z-peak at the LHC. Our results consistently combine next-to-next-to-leading order QCD corrections and next-to-leading order electroweak effects, and include the leading photon-initiated processes using a recent extraction of the photon distribution function. We focus on the effects of electroweak corrections and of photon-photon scattering contributions, and demonstrate which kinematic distributions exhibit sensitivity to these corrections. We show that a combination of measurements allows them …
Elastic diffractive scattering of nucleons is described in terms of Regge-eikonal approach. It is demonstrated that, in a wide kinematic region (starting from the U-70 energies), the eikonal of proton-proton scattering can be approximated by the sum of two Reggeon exchange terms (namely, the so-called soft Pomeron and $f$-Reggeon contributions). The range of applicability of the considered approximation is determined. The predictive value of the proposed phenomenological scheme is verified.
We discuss the profile of the impact--parameter dependent elastic scattering amplitude. Extraction of impact-parameter dependence from the dataset with inclusion of the experimental data on elastic scattering at the LHC energies helps to reveal the asymptotics of hadron interactions. Analysis of the data clearly indicates that the impact-parameter elastic scattering amplitude exceed the black disk limit at the LHC energy 7TeV and the inelastic overlap function reaches its maximum value at $b>0$
In this work, we probe a class of neutrino mass models through the lepton flavor violating interactions of a singlet charged scalar, $S^{\pm}$ at the LHC proton-proton collisions with 8 TeV and 14 TeV energies. This scalar couples to the leptons and induces many processes such as $pp\rightarrow\ell^{\pm}\ell^{\pm}\ell^{\mp}+\slashed{E}_{T}$. In our analysis we discuss the opposite sign same flavor leptons signal, as well as the background free channel with the tau contribution which can enhance the signal/background ratio for center of mass energies $\sqrt{s}$= 8 TeV and $\sqrt{s}$ = 14 TeV.
Low-|t| structures in elastic scattering at the LHC
该研究预言 LHC 的 pp 弹性散射在低 |t| 区域存在结构，并将 t≈-0.1 GeV² 处的斜率变化归因于散射振幅 |t| 道的 4m_π² 分支点，同时指出衍射锥上或有微小振荡。
Modern models of high energy elastic hadron-hadron scattering predict an oscillation character of differential cross sections at the LHC energy of 14 TeV and at a sufficiently high momentum transfer. The Totem collaboration did not see the oscillations at 7 TeV. According to some predictions, the oscillations are weak at 7 TeV in the studied 4-momentum transfer range (|t|< 2.5 GeV$^2$). They may be beyond the range of the experiment. But a direct extension of the Totem collaboration data on the pp-scattering at 7 TeV above |t|\sim 2.5 GeV$^2$ contradicts previous measurements. Thus the collabo…
We discuss how the main features of the recent LHC data on elastic scattering can be described by a QCD-inspired formalism with a dynamical infrared mass scale. For this purpose new developments on a dynamical gluon mass approach are reported, with emphasis on a method to estimate uncertainty bounds in the predictions for the high-energy scattering observables. We investigate the effects due to the correlations among the fixed and free parameters involved and show that the band of predictions are consistent with the recent data from the TOTEM experiment, including the forward quantities and th…
The theory of the perturbative pomeron, due to Lipatov and collaborators, is used to compute the probability of observing parton-parton elastic scattering and rapidity gaps between jets in hadron collisions at SSC and LHC energies.
In this talk, I describe the general characteristics of radiative neutrino mass models that can be probed at the LHC. I then cover the constraints on a new, explicit model of this type.
The ATLAS and CMS experiments at the CERN LHC have collected about 25 inverse femtobarns (fb) of data each at the end of their 8 TeV run, and ruled out a huge swath of parameter space in the context of Minimally Supersymmetric Standard Model (MSSM). Limits on masses of the gluino have been pushed to above 1 TeV. These limits are however extremely model dependent and do not always reflect the level of exclusion. So far the limits on the gluino mass using the simplified model approach only constrained its value using its three-body decays. We show in this work that already existing ATLAS and CMS…
Predictions of the elastic proton-proton cross sections at energies of LHC are calculate on the base of the high energy dynamical model. The growth of $ds/dt$ at fixed transfer momenta are shown. The form of eikonal of elastic hadron scattering at super high energies is discussed.
The problems linked with the extraction of the basic parameters of the hadron elastic scattering amplitude at the LHC are explored. It is shown that one should take into account the saturation regime which will lead to new effects at the LHC.
We have investigated in detail a model that contains an additional SU(2) singlet and triplet scalar fields than the Standard Model (SM). This allows the radiative generation of Majorana neutrino masses at two-loop order with the help of doubly charged Higgs bosons that arise from the extended Higgs sector. We studied in detail the phenomenology of the Higgs and neutrino sectors of the model. We give the analytical form of the masses of scalar and pseudoscalar bosons and their mixings, and the structure of the active neutrino mass matrix. It is found that the model accommodates only normal neut…
The problems linked to the extraction of the basic parameters of the hadron elastic scattering amplitude at the LHC are explored. The impact of the Black Disk Limit (BDL)$-$ which constitutes a new regime of the scattering processes - on the determination of these values is examined.
Compact analytical formulae for QED radiative corrections in the processes of elastic $e-p$ scattering are obtained in the case when kinematic variables are reconstructed from the recoil proton momentum measured. Numerical analysis is presented under kinematic conditions of current experiments at JLab.
We study the radiative correction to $p_\perp$-broadening of a fast quark in a quark-gluon plasma beyond the soft gluon approximation. We find that the radiative contribution to quark $\langle p_\perp^2\rangle$ for RHIC and LHC conditions is negative.
We discuss the theoretical approach and practical algorithms for simulation of radiative events in elastic ep-scattering. A new Monte Carlo generator for real photon emission events in the process of elastic electron-proton scattering is presented. We perform a few consistency checks and present numerical results.
Lepton Number Violation at the LHC in Radiative Neutrino Mass Models with Leptoquarks
该研究探讨了在LHC上通过轻子quark模型观察电荷宇称破坏的可能性，并通过实验验证中微子的Majorana性质。
We parametrize TOTEM data for the elastic differential pp cross section at sqrt(s)=7 TeV in terms of two exponentials with a relative phase. We employ two previously derived sum rules for pp elastic scattering amplitude in impact parameter space to check whether asymptotia has been reached at the LHC. A detailed study of the TOTEM data for the elastic differential cross section at sqrt(s)=7 TeV is made and it is shown that, within errors, the asymptotic sum rules are satisfied at LHC. We propose to use this parametrization to study forthcoming higher energy data.
We investigate the effect of high order radiative corrections in unpolarized electron proton elastic scattering and compare with the calculations at lowest order, which are usually applied to experimental data. We show that higher order terms play a role, starting from values of the momentum transfer squared, $Q^2$, larger than the electron mass. Particular attention is devoted to the $ε$ dependence of radiative corrections.
Elastic proton-proton scattering is reviewed starting from the results of the LHC experiments conducted by the TOTEM and ATLAS collaborations, and the HEGS model and a simple phenomenological parametrisation are compared with the new data on the differential elastic proton-proton scattering cross section, which detect a non-exponential behaviour of the differential cross sections in the first diffraction cone. We consider the influence of various assumptions on the extraction of the elastic scattering parameters, and on the deduction of the total cross section.
A model of $pp$ and $\bar{p}p$ elastic scattering developed previously to analyze ISR and SPS Collider data is extended to predict $pp$ elastic differential cross section at LHC at c.m. energy of 14 TeV and momentum transfer range $|t|=0$ - 10 GeV$^2$. Role of the gauged linear $σ$-model as an underlying field theory model describing nucleon structure and elastic scattering is discussed. Possibility of finding evidence of a chiral phase transition at large $|t|$ in the proposed TOTEM project at LHC is pointed out.
Predictions for the total, elastic and single diffractive cross sections calculated for the LHC in the framework of the Miettinen-Pumplin model are presented. The total cross section is expected to be 15% smaller than that determined by Donnachie and Landshoff in the model with soft pomeron. The diffractive cross section is almost constant in the Tevatron-LHC energy range.
An alternative calculation of the lowest order electroweak radiative corrections to the single W-boson production in hadron-hadron collision in the framework of the quark parton model without any absorption of the collinear quark singularity into the parton distributions is carried out. Numerical analysis under Tevatron and LHC kinematic conditions is performed.
The explicit formulae for radiative correction (RC) calculation for elastic $ep$-scattering is presented. Two typical measurements of polarization observables such as beam-target asymmetry or recoil proton polarization, are considered. Possibilities to take into account realistic experimental acceptances are discussed. The Fortran code MASCARAD for providing the RC procedure is presented. Numerical analysis is done for kinematical conditions of TJNAF.
We discuss the possibility of measuring leading neutron production at the LHC. These data could be used to extract from it $π^+ p$ and $π^+π^+$ cross-sections. In this note we give some estimates for the case of elastic cross-sections and discuss related problems and prospects.
The structure and algorithms of the Monte-Carlo generator ELRADGEN 2.0 designed to simulate radiative events in polarized ep-scattering are presented. The full set of analytical expressions for the QED radiative corrections is presented and discussed in detail. Algorithmic improvements implemented to provide faster simulation of hard real photon events are described. Numerical tests show high quality of generation of photonic variables and radiatively corrected cross section. The comparison of the elastic radiative tail simulated within the kinematical conditions of the BLAST experiment at MIT…
We discuss effects of reflective scattering for hadron and heavy nuclei collisions at the LHC and asymptotical energies. It is shown that the reflective scattering might lead to decreasing matter density with energy beyond the LHC energies. Limiting form of energy dependence of hadron density is obtained. Unitarity upper bound for the absolute value of the real part of elastic scattering amplitude and two-particle inelastic binary reactions amplitudes in impact parameter representation is two times less than the corresponding bound for the imaginary part of the elastic scattering amplitude. Th…
Radiative W production at hadron colliders is an important testing ground for the Standard Model. We consider W gamma gamma production which is sensitive to the quartic WW gamma gamma coupling. Furthermore the Standard Model amplitude for this process contains a radiation zero. We present a calculation of the NLO QCD corrections for W gamma gamma production at the LHC.
The kinematical difference between the description of radiative effects for fixed $Q^2$ vs a fixed scattering angle in the elastic lepton-proton ($lp$)-scattering is discussed. The technique of calculation as well as explicit expressions for radiative corrections to the lepton current in unpolarized elastic $lp$-scattering for these two cases are presented without using an ultrarelativistic approximation. A comparative numerical analysis within kinematic conditions of Jefferson Lab measurements and MUSE experiment in PSI is performed.
Model independent radiative correction to the recoil proton polarization for the elastic electron-proton scattering is calculated within method of electron structure functions. The explicit expressions for the recoil proton polarization are represented as a contraction of the electron structure and the hard part of the polarization dependent contribution into cross-section. The calculation of the hard part with first order radiative correction is performed. The obtained representation includes the leading radiative corrections in all orders of perturbation theory and the main part of the secon…
Improvement of the radiative correction scheme for the deep inelastic scattering on the heavy targets is discussed. Arguments that the contribution of the radiative tail from the elastic peak should be calculated without use of the Born approximation in the case of the heavy target scattering are presented. The semianalytical approach based on the classical solution of the old bremsstrahlung problem is shortly described. The numerical results for the new correction factor are presented for the scattering on tin and lead.
A numerical analysis of QED radiative corrections for elastic e(mu)p cattering in hadronic variables at energies of the current experiment at JLab is performed. The explicit formulas from the review of Akhundov et al. resulting from the integration over the phase space of leptonic variables plus photon are used to obtain the values of the cross sections and the radiative correction factor for unpolarized lepton-proton scattering. Our numerical results agree with the corresponding results arising from the formulas of Afanasev et al.
Z Boson Radiative Decay $Z\to μ^+ μ^- γ$ at the LHC
本文研究了Z玻色子衰变为μ+μ-γ的过程，通过标准模型精度分析和新物理投影，展示了该衰变模式在LHC上可达到亚百分比级别的统计精度，并探讨了其对轴子样粒子和异常U(1)_X规范玻色子的灵敏度。
In the light of LHC data, we discuss the global description of all high energy elastic and diffractive data, using a one-pomeron model, but including multi-pomeron interactions. The LHC data indicate the need of a $k_t(s)$ behaviour, where $k_t$ is the gluon transverse momentum along the partonic ladder structure which describes the pomeron. We also discuss tensions in the data, as well as the $t$ dependence of the slope of $dσ_{el}/dt$ in the small $t$ domain.
Using a unified analytic representation for the elastic scattering amplitudes of pp scattering valid for all energy region, the behavior of observables in the LHC collisions in the range $\sqrt{s}$= 2.76 - 14 TeV is discussed. Similarly to the case of 7 TeV data, the proposed amplitudes give excellent description of the preliminary 8 TeV data. We discuss the expected energy dependence of the observable quantities, and present predictions for the experiments at 2.76, 13 and 14 TeV.
The study of ep-scattering at LEP x LHC offers an interesting opportunity to search for additional heavy neutral gauge bosons. We study the influence of radiative corrections, especially of the potentially large QED contributions, to the expected cross sections. These corrections are typically of the same order as the effect searched for or even larger and have to be taken into account properly.
The possibility to study elastic and diffractive physics in pp collisions at LHC is investigated. For this purpose we have considered detectors close to the beam in conjunction with the magnetic elements of the accelerator to provide a high precision spectrometer for very forward final state protons. The geometrical acceptance is given and momentum resolution is calculated for different spatial resolution detectors.
QED radiative corrections to elastic electron-proton scattering at low energies are discussed. Corrections to the electron line and effects due to vacuum polarization are computed. Higher order effects are estimated for the conditions of the experiment on the electric and magnetic proton form factors by A1 Collaboration. Calculations are performed within the next-to-leading approximation. Inclusion of the higher order effects can affect the value of the proton charge radius extracted from the experimental data.
We discuss a model which gives a `global' description of the wide variety of high-energy elastic and diffractive data that are presently available, particularly from the LHC experiments. The model is based on only one pomeron pole, but includes multi-pomeron interactions. Significantly, the LHC measurements require that the model includes the transverse momentum dependence of the intermediate partons as a function of their rapidity, which results in a rapidity (or energy) dependence of the multi-pomeron vertices.
We will recall the main feaatures of an accurate phenomenological model to describe successfully near-forward elastic scattering in a wide energy range, including ISR, SPS and Tevatron colliders. A large step in energy domain is accomplished with the LHC collider, presently running, giving the opportunity to confront the new data with the predictions of our theoretical approach.
Universal properties of elastic pp cross section from the ISR to the LHC
本研究探究从ISR到LHC能区弹性微分pp截面峰谷位之比恒定的唯象学，验证几何标度在LHC的适用性，并分析其对ρ参数和峰谷截面值比的影响。
We describe radiative corrections to bremsstrahlung and their application to high energy collider physics, focusing on the applications to luminosity measurement, fermion pair production and radiative return. We review the status of one loop radiative corrections in BHLUMI and the KKMC, including cross checks with newer results developed independently for radiative return. We outline a YFS-exponentiated approach to the Drell-Yan process for LHC physics, including a discussion of the relevant radiative corrections.
In this paper we propose the study of the diffractive quarkonium photoproduction in $pp$ collisions at LHC energies to probe the photon flux associated to a ultrarelativistic proton. The total photon distribution is expected to be given in terms of the elastic and inelastic components. Distinctly from the elastic photon component which can be determined from the elastic form factors, the magnitude of the inelastic component still is an open question. We consider the current parametrizations for the photon distribution of a proton and estimate the rapidity distributions and total cross sections…
Under the assumption of total absorption and dominance of the imaginary part of the scattering amplitude, we present a sum rule for any hadronic elastic differential cross-section ${dσ}\over{dt}$: the dimensionless quantity ${{1}\over{2}}\int (dt)\sqrt{{{1}\over π}{{dσ}\over{dt}}} \to 1$, at asymptotic energies. Experimental data from ISR and Tevatron confirm a trend towards its saturation and some estimates are presented for LHC. Its universality and further consequences for the nature of absorption in QCD based models for elastic and total cross-sections are explored.
An empirical model for the $pp$ elastic differential cross section is proposed. Inspired by early work by Barger and Phillips, we parametrize the scattering amplitude in building blocks, comprising of two exponentials with a relative phase, supplementing the dominant term at small $-t$ with the proton form factor. This model suitably applies to LHC7 and ISR data, enabling to make simple predictions for higher LHC energies and to check whether asymptotia might be achieved.
The analyses of elastic collisions of charged nucleons have been based standardly on West and Yennie formula. However, this approach has been shown recently to be inadequate from experimental as well as theoretical points of view. The eikonal model seems to be more pertinent as it enables to determine physical characteristics in impact parameter space. The contemporary phenomenological models cannot give, of course, any definite answer as the elastic collisions may be interpreted differently, as central or peripheral processes. Nevertheless, the predictions for the planned LHC energy have been…
We present the unified description of the existing data on elastic small angle $pp$ and $p \bar p$ scattering at the energies 1.8, 1.96, 2.76, 7, 8 and 13~TeV in the framework of Additive Quark Model. The agreement with the data is quite reasonable.
Here we consider a contribution of Delta(1232) resonance to real photon radiative corrections for elastic $ep$-scattering. The effect is found to be small for past experiments to study unpolarized cross section as well as for the recent VEPP-3 experiment to investigate two-photon exchange effects by precision measurement of $e^\pm p$-scattering cross sections ratio.
A precise determination of the $W$ boson mass at the CERN LHC requires a theoretical calculation in which the effect of the initial-state multiple soft-gluon emission and the final-state photonic correction are simultaneously included. Here, we present such a calculation and discuss its prediction on a few most relevant distributions of the decay leptons.
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