In this work the vector boson scattering process is investigated through the reaction $pp\rightarrow 2 \mathrm{jets} + W^\ast W^\ast \rightarrow 2 \mathrm{jets} + lν_l l'ν_l'$, where $W^\ast$ denote in general off-shell $W^+$, in the EFT approach with the HL-LHC and HE-LHC experiments in mind. We have investigated the discovery potential of certain classes of the EFT "models" of both the SMEFT and HEFT bases with the particular emphasis on using the EFT "models" in their region of validity. A novel method has been proposed for determining the discovery regions of physics beyond the SM, described by the EFT "models". Independent of the basis chosen, the discovery regions are found to be non-empty. We then compare differences in experimental signatures between SMEFT and HEFT, which is an important step for distinguishing between the two hypotheses in the future data. Finally, we investigated what the effect on the discovery regions is when increasing the $pp$ collision energy.
Double parton scattering, i.e. two parton hard scattering processes in the same hadron-hadron collision, may constitute an important background for Higgs and other new particle searches at the LHC. We point out that like-sign W pair production provides a relatively clean way of searching for, and calibrating, double parton scattering at the LHC.
The coherent contribution of all neutrons in neutrino nucleus scattering due to the neutral current is examined considering the Spallation Neutron Source (SNS) as a source of neutrinos. SNS is a prolific pulsed source of electron and muon neutrinos as well as muon antineutrinos.
The measurement of the polarized gluon distribution function Delta_G/G using current-target correlations in the Breit frame of deep inelastic scattering is proposed. The approach is illustrated using a Monte Carlo simulation of polarized $ep$-collisions for HERA energies.
We consider different methods and observables which can be obtained by the measurement of neutrino scattering off nucleons and nuclei with the purpose of finding evidence for the strange form factors of the nucleon, which enter into structure of the nucleonic weak neutral current.
The effect of anomalous gauge couplings on polarized $e^- e^-$ scattering cross sections is examined. It turns out that different combinations of beam polarizations provide constraints that are complementary to each other and to those obtained from other experiments, such as $e^+ e^-$, $e^- γ$ and $γγ$ collisions.
The appearance of the antishadow scattering mode at Tevatron-Collider energies is considered on the basis of unitarity and geometrical notions on hadron interactions
The problem of electron-proton scattering is handed over both the elastic and inelastic scattering. Two models are presented in this sense. The first, depends on the multi photon exchange ladder diagram, where the transition matrix is expanded in multi steps form. The second model uses the multi peripheral mechanism developed for the electromagnetic field. It allows the particle production in the inelastic scattering processes. An iterative procedure is found and inserted in a Monte Carlo program to reproduce the differential cross section of the reaction. The comparison with the experimental …
We argue that the production of forward jets in polarised deep inelastic scattering can be a useful tool for probing the double $ln^2(1/x)$ resummation effects which control the polarised deep inelastic scattering for small values of the Bjorken parameter $x$. We solve the corresponding integral equations generating the double $ln^2(1/x)$ resummation and calculate the differential structure function describing the forward jet production in the small $x$ regime which can possibly be probed by the polarised HERA measurements. We show that these structure functions should exhibit the characterist…
The magnitude of the double-spin asymmetry A_{NN} in polarized proton elastic scattering is estimated using results from an earlier determination of the spin-flip coupling of the leading Regge poles (cf. T.L.Trueman, Proceedings of the 16th International Spin Physics Symposium SPIN 2004, eds. F. Bradamante et al, World Scientific, 2005.) The required Regge cuts are estimated using the absorptive Regge model. This estimate is then used to determine the sensitivity of experiments at RHIC to the presence of the Odderon.
We present a review of the present status of the problem of neutrino masses and mixing including a survey of theoretical motivations and models, experimental searches and implications of recently appeared solar and atmospheric neutrino data, which strongly indicate nonzero neutrino masses and mixing angles.
We demonstrate that the measurement of an azimuthal angle asymmetry in deeply virtual Compton scattering (DVCS) at HERA energies, is experimentally feasible and allows one to determine for the first time the ratio $η$, of the real to imaginary part of the DIS amplitude. We further show that such a measurement would discriminate between different scenarios of the energy dependence of $F_2(x,Q^2)$ at energies beyond those reachable at HERA.
Azimuthal asymmetry of vector-meson production in single-transversely polarized proton-proton collisions ($p\up p$) is calculated in the string model of particle production. The asymmetry is generated only during fragmentation of a high-energy quark into hadrons. The obtained asymmetry of the $ρ^\pm$ is opposite in sign to that of $π^\pm$ mesons. On the other hand, an asymmetry appearing during parton scattering would contribute with the same sign to that of vector and pseudoscalar mesons. Thus, a combined measurement of both can be used to estimate the contribution to the asymmetry from parto…
Perturbative QCD predicts the behavior of scattering at high energies and fixed (sufficiently large) transferred momenta in terms of the BFKL pomeron (or short distance pomeron). We study the prospects for testing these predictions in two-photon processes at LEP200 and a possible future e+ e- collider. We argue that the total cross section for scattering two photons sufficiently far off shell provides a clean probe of BFKL dynamics. The photons act as color dipoles with small transverse size, so that the QCD interactions can be treated perturbatively. We analyze the properties of the QCD resul…
We evaluate the two-loop ${\cal O}(m_e^2/s)$ contribution to the wide-angle high-energy electron-positron scattering in the double-logarithmic approximation. The origin and the general structure of the power-suppressed double logarithmic corrections are discussed in detail.
I discuss possibilities to observe the instanton-induced contributions to deep inelastic scattering which correspond to nonperturbative exponential corrections to the coefficient functions in front of parton distributions of the leading twist.
We study the production of same-sign W boson pairs at the LHC in double parton interactions. Compared with simple factorised double parton distributions (dPDFs), we show that the recently developed dPDFs, GS09, lead to non-trivial kinematic correlations between the W bosons. A numerical study of the prospects for observing this process using same-sign dilepton signatures, including same-sign WWjj, di-boson and heavy flavour backgrounds, at 14 TeV centre-of-mass energy is then performed. It is shown that a small excess of same-sign dilepton events from double parton scattering over a background…
We study the transverse momentum ($p_T$) spectrum of charged particles produced in deep inelastic scattering (DIS) at small Bjorken $x$ in the central region between the current jet and the proton remnants. We calculate the spectrum at large $p_T$ with the BFKL $\ln (1/x)$ resummation included and then repeat the calculation with it omitted. We find that data favour the former. We normalize our BFKL predictions by comparing with HERA data for DIS containing a forward jet. The shape of the $x$ distribution of DIS + jet data are also well described by BFKL dynamics.
We present the consequences of a large radiative correction term coming from Supersymmetry (SUSY) upon the electron neutrino fluxes streaming off a core- collapse supernova using a 3-flavor neutrino-neutrino interaction code. We explore the interplay between the neutrino-neutrino interaction and the effects of the resonance associated with the mu-tau neutrino index of refraction. We find that sizeable effects may be visible in the flux on Earth and, consequently, on the number of events upon the energy signal of electron neutrinos in a liquid argon detector. Such effect could lead to a probe f…
We study the electromagnetic contribution to elastic neutrino-proton and neutrino-neutron scattering processes. The neutrino electromagnetic charge, magnetic, electric, and anapole form factors of both diagonal and transition types in the mass basis are taken into account in the present formalism. When treating the nucleon electromagnetic vertex, we take into account not only the charge and magnetic form factors of a nucleon, but also its electric and anapole form factors. We examine how the effects of the neutrino magnetic moment can be disentangled from those of the strange quark contributio…
U_A(1) dynamics have the potential to induce a polarised condensate inside a nucleon. The formation of this condensate is related to the realisation of U_A(1) symmetry breaking by tunneling processes such as instantons. If it is present, the polarised condensate induces a term in g_1 which has support only at x=0. Tunneling processes then induce a net transfer of ``spin'' from finite x to x=0. The polarised condensate may be measured by comparing the flavour-singlet axial charges which are extracted from polarised deep inelastic and nu p elastic scattering experiments.
We present the results of a detailed study of the large transverse momentum Drell-Yan process, pp --> (Gamma^*, Z^*)X --> l^+l^- X at collider energies, with either one or both protons polarised, allowing the study of single- and double-spin asymmetries respectively. We show how these asymmetries obtained from angular distributions of the leptons in the Gamma^* (or Z^*) rest-frame, can be used to get information on the polarised parton distributions. Numerical results for the asymmetries and the cross-sections are presented, and the sensitivity of the asymmetries to the initial parton distribu…
In this thesis, we discuss theoretical properties of various Higgs sectors, and we analyze constraints from current experimental data, and then we study collider signatures in each Higgs sector. In Part I, we focus on the phenomenology of various extended Higgs sectors such as the two Higgs doublet model, the Higgs triplet model and Higgs sectors in supersymmetric standard models. In Part II, we discuss new physics models at the TeV scale, in which the Higgs sector is extended, and neutrino masses, dark matter and/or baryon asymmetry of the Universe can be explained.
The S-wave $π- π$ scattering lengths $a_0$ and $a_2$ are calculated to the lowest order of $1/N_c$ expansion in the general framework of SU(2) NJL model beyond mean-field approximation. It is shown that using the universal curve of $a_0$ and $a_2$ the four NJL parameters, i.e., the current quark mass $m_0$, the four fermion coupling constant $G$, the quark momentum cut-off $Λ_f$ and the meson momentum cut-off $Λ_b$, also the S-wave $π- π$ scattering lengths in NJL model can be uniquely determined.
We argue that the recent LHCb observation of J/psi-pair production indicates a significant contribution from double parton scattering, in addition to the standard single parton scattering component. We propose a method to measure the double parton scattering at LHCb using leptonic final states from the decay of two prompt J/psi mesons.
We propose that the process of triple prompt $J/ψ$ hadroproduction is a very clean hard probe of multiple-parton scatterings at high-energy hadron colliders, especially the least known triple-parton scattering. A first complete study is carried out by considering single-, double-, and triple-parton scatterings coherently. Our calculation shows that it is a golden channel to probe double- and triple-parton scatterings, as the single-parton scattering is strongly suppressed. The predictions of the (differential) cross sections in proton-proton collisions at the LHC and the future higher-energy h…
We suggest that $e\to μ$ conversion in low-energy electron-nucleus scattering is a new and potentially observable indirect signal of supersymmetry and should be searched for in experiment. We estimate the rate for this process in a straightforward calculation taking into account the existing constraint from non-observation of the $μ\to eγ$ decay and find the cross-section to be $σ< 10^{-8} $fb.
Several proposals for studying neutrinos with large detectors are currently under discussion. We suggest that they could provide a precise measurement of the electroweak mixing angle as well as a probe for new physics, such as non-standard neutrino interactions (NSI), and the electroweak gauge structure. We illustrate this explicitly for the case of the LENA proposal, either with an artificial radioactive source or by using the solar neutrino flux.
New mode in the hadron scattering is predicted to appear at the energies beyond $\sqrt{s}\simeq 2$ TeV: the antishadow scattering mode and the experiments at LHC and VLHC in hadronic reactions will be able to reveal it. The appearance of the antishadow scattering mode at these energies is considered on the basis of unitarity and geometrical notions of hadron interactions. Connections with the nonperturbative--QCD models are discussed.
We examine the current constraints and future sensitivity of Coherent Elastic Neutrino-Nucleus Scattering (CE$ν$NS) experiments to mixing scenarios involving a $Z^\prime$ which interacts via portals with the Standard Model. We contrast the results against those from fixed target, atomic parity violation, and solar neutrino experiments. We demonstrate a significant dependence of the experimental reach on the $Z'$ coupling non-universality and the complementarity of CE$ν$NS to existing searches.
If supersymmetry is discovered at future colliders, what can we learn? While our appreciation of the variety of possible supersymmetric models has grown tremendously in recent years, most attempts to answer this question have been in the context of some simple and highly restrictive framework, such as minimal supergravity. In this talk I describe new probes of phenomena that are generic in models beyond the minimal framework. These include tests of supersymmetric flavor and CP violation and probes of kinematically inaccessible superparticle sectors through ``super-oblique corrections.'' Such p…
Multiple parton scattering and induced parton energy loss in deeply inelastic scattering (DIS) off heavy nuclei is studied within the framework of generalized factorization in perturbative QCD with a complete calculation beyond the helicity amplitude (or soft bremsstrahlung) approximation. Such a calculation gives rise to new corrections to the modified quark fragmentation functions. The effective parton energy loss is found to be reduced by a factor of 5/6 from the result of helicity amplitude approximation.
We revisit the calculation of the medium-induced gluon spectrum in a finite QCD and develop a new approach that goes beyond multiple soft scattering approximation. We show by expanding around the harmonic oscillator that the first two orders encompass the two known analytic limits: single hard and multiple soft scattering regimes, valid at high and low frequencies, respectively. Finally, we investigate the sensitivity of our results to the infrared and observe that for large media the spectrum is weakly dependent on the infrared medium scale.
Atomic Parity Violation (APV) is usually quantified in terms of the weak nuclear charge $Q_W$ of a nucleus, which depends on the coupling strength between the atomic electrons and quarks. In this work, we review the importance of APV to probing new physics using effective field theory. Furthermore, using $SU(2)$ invariance, we correlate our findings with those from neutrino-nucleus coherent scattering. Moreover, we investigate signs of parity violation in polarized electron scattering and show how precise measurements on the Weinberg angle, $\sin θ_W$, will give rise to competitive bounds on l…
Low-energy tests of fundamental symmetries and studies of neutrino properties provide a powerful window on physics beyond the Standard Model (BSM). In this article, we provide a basic theoretical framework for a subsequent set of articles that review the progress and opportunities in various aspects of the low-energy program. We illustrate the physics reach of different low-energy probes in terms of an effective BSM mass scale and illustrate how this reach matches and, in some cases, even exceeds that accessible at the high energy frontier.
We present a unified relativistic approach to inclusive electron scattering based on the relativistic Fermi gas model and on a phenomenological extension of it which accounts for the superscaling behaviour of $(e,e')$ data. We present results in the $Δ$ resonance region and in the highly inelastic domain and show some application to neutrino scattering.
Motivated by recently observed tension between $O\left(α_s^2\right)$ calculations of very large transverse momentum dependence in both semi-inclusive deep inelastic scattering and Drell-Yan scattering, we repeat the details of the calculation through $O\left(α_s^2\right)$ transversely differential cross section. The results confirm earlier calculations, and provide further support to the observation that tension exists with current parton distribution and fragmentation functions.
The LHC possibilities to constrain the parameters of the Randall-Sundrum-like model with one warped extra dimension and small curvature through the diphoton production in the photon-induced process pp -> p gamma gamma p -> p' gamma gamma p' are investigated. Two acceptances of the forward detectors, 0.015 < xi < 0.15 and 0.015 < xi < 0.5, where xi is the fractional proton momentum loss of the incident protons, are considered. The sensitivity bounds on the 5-dimensional gravity scale are obtained as a function of the LHC integrated luminosity.
In the Standard Model the total lepton number is conserved. Thus, neutrinoless double-beta decay, in which the total lepton number is violated by two units, is a probe of physics beyond the Standard Model. In this review we consider the basic mechanism of neutrinoless double-beta decay induced by light Majorana neutrino masses. After a brief summary of the present status of our knowledge of neutrino masses and mixing and an introduction to the seesaw mechanism for the generation of light Majorana neutrino masses, in this review we discuss the theory and phenomenology of neutrinoless double-bet…
We study deep inelastic scattering at large-'t Hooft coupling and finite $x$ from gauge/string duality beyond single-hadron final states which gives the leading large-$N_c$ contribution. Within the supergravity approximation, we calculate the subleading large-$N_c$ contribution by introducing an extra hadron into the final states. We find the contribution from these double-hadron final states will dominate in the Bjorken limit $q^2\rightarrow \infty$ compared with the single-hadron states. We discuss the implications of our results.
We show that underground experiments like LUX/LZ, PandaX-II, XENON, and PICO could discover dark matter up to the Planck mass and beyond, with new searches for dark matter that scatters multiple times in these detectors. This opens up significant discovery potential via re-analysis of existing and future data. We also identify a new effect which substantially enhances experimental sensitivity to large dark matter scattering cross-sections: while passing through atmospheric or solid overburden, there is a maximum number of scatters that dark matter undergoes, determined by the total number of s…
The present and future prospects of intermediate-energy semileptonic neutral current studies are reviewed. Possibilities for using neutrino and parity-violating electron scattering from nucleons and nuclei to study hadron structure and nuclear dynamics are emphasized, with particular attention paid to probes of the nucleon's strangeness content. Connections are drawn between such studies and tests of electroweak gauge theory using electron or neutrino scattering. Outstanding theoretical issues in the interpretation of semileptonic neutral current measurements are highlighted, and the prospects…
We study the impact of virtual axions on the polarization of photons inside a cavity during the interaction of high-power laser pulses. A novel detection scheme for measuring the axion-induced ellipticity signal during the Light-by-Light (LBL) scattering process is investigated. We show that a momentum exchange between photons in a probe laser beam and a high-intensity target beam may lead to a resonance at the physical mass of the axion. Consequently, the resonant enhancement of vacuum birefringence gives rise to a large ellipticity signal. This signal enhancement can be applied in order to d…
Thermal evolution of neutron stars (NSs) is studied as a probe of physics beyond the standard model. We first review the standard cooling theory of NSs in detail, with an emphasis on the roles of nucleon superfluidity. Then we discuss non-standard evolution with axion and dark matter (DM); axion production enhances the cooling while DM accretion leads to heating of NSs. To evaluate the effect of DM heating, we need to compare it to the rotochemical heating, which is caused by the out-of-equilibrium beta processes in a NS. In the dissertation, we also investigate the rotochemical heating in the…
Using non-linear evolution equations of QCD, we compute the von Neumann entropy of the system of partons resolved by deep inelastic scattering at a given Bjorken $x$ and momentum transfer $q^2 = - Q^2$. We interpret the result as the entropy of entanglement between the spatial region probed by deep inelastic scattering and the rest of the proton. At small $x$ the relation between the entanglement entropy $S(x)$ and the parton distribution $xG(x)$ becomes very simple: $S(x) = \ln[ xG(x) ]$. In this small $x$, large rapidity $Y$ regime, all partonic micro-states have equal probabilities -- the p…
Within a plane-wave approximation in scattering, an incoming wave packet's Wigner function stays everywhere positive, which obscures such purely quantum phenomena as non-locality and entanglement. With the advent of the electron microscopes with subnanometer-sized beams one can enter a genuinely quantum regime where the latter effects become only moderately attenuated. Here we show how to probe negative values of the Wigner function in scattering of a coherent superposition of two Gaussian packets with a non-vanishing impact-parameter between them (a Schrödinger's cat state) by atomic targets.…
Due to integrability, baryon-baryon scattering in the massless Gross-Neveu model at large N features only forward elastic scattering. A bare mass term breaks integrability and is therefore expected to induce backward elastic scattering as well as inelastic reactions. We confirm these expectations by a study of baryon-baryon scattering in the massive Gross-Neveu model near the non-relativistic limit. This restriction enables us to solve the time-dependent Hartree-Fock equations with controlled approximations, using a combination of analytical methods from an effective field theory and the numer…
