Y.N. Srivastava

The Physics Programme Of The MoEDAL Experiment At The LHC

The MoEDAL experiment at Point 8 of the LHC ring is the seventh and newest LHC experiment. It is dedicated to the search for highly-ionizing particle avatars of physics beyond the Standard Model, extending significantly the discovery horizon of the LHC. A MoEDAL discovery would have revolutionary implications for our fundamental understanding of the Microcosm. MoEDAL is an unconventional and largely passive LHC detector comprised of the largest array of Nuclear Track Detector stacks ever deployed at an accelerator, surrounding the intersection region at Point 8 on the LHC ring. Another novel feature is the use of paramagnetic trapping volumes to capture both electrically and magnetically charged highly-ionizing particles predicted in new physics scenarios. It includes an array of TimePix pixel devices for monitoring highly-ionizing particle backgrounds. The main passive elements of the MoEDAL detector do not require a trigger system, electronic readout, or online computerized data acquisition. The aim of this paper is to give an overview of the MoEDAL physics reach, which is largely complementary to the programs of the large multipurpose LHC detectors ATLAS and CMS.

Low-pt jets and the rise with energy of the inelastic cross section

Abstract The contribution of QCD jets to the rise with energy of the inelastic cross section is discussed quantitatively and found to be large. It is seen that the inclusive jet yield is the fastest growing component of the total cross section. The dependence of this yield upon the rapidity cuts, the choice of parton densities, the QCD scale Q 2 and the transverse momentum cutoff p cut are examined. At higher energies, multiple parton scattering processes are seen to be non-negligible. Extrapolations of the low- p t jet yield to the Tevatron are presented also.

Jets in Minimum Bias Physics

Abstract We discuss and present phenomenological evidence to support the hypothesis that several new phenomena observed in low- p t physics are due to the presence of low- x QCD jets in minimum bias physics. The phenomena we examine are KNO scaling violations, growth of 〈 p t 〉 with multiplicity and rise of the non-diffractive part of the total cross section.

Search for magnetic monopoles with the MoEDAL forward trapping detector in 13 TeV proton-proton collisions at the LHC

MoEDAL is designed to identify new physics in the form of long-lived highly ionizing particles produced in high-energy LHC collisions. Its arrays of plastic nuclear-track detectors and aluminium trapping volumes provide two independent passive detection techniques. We present here the results of a first search for magnetic monopole production in 13xa0TeV proton-proton collisions using the trapping technique, extending a previous publication with 8xa0TeV data during LHC Run 1. A total of 222xa0kg of MoEDAL trapping detector samples was exposed in the forward region and analyzed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges exceeding half the Dirac charge are excluded in all samples and limits are placed for the first time on the production of magnetic monopoles in 13xa0TeV pp collisions. The search probes mass ranges previously inaccessible to collider experiments for up to five times the Dirac charge.

Search for magnetic monopoles with the MoEDAL prototype trapping detector in 8 TeV proton-proton collisions at the LHC

A bstractThe MoEDAL experiment is designed to search for magnetic monopoles and other highly-ionising particles produced in high-energy collisions at the LHC. The largely passive MoEDAL detector, deployed at Interaction Point 8 on the LHC ring, relies on two dedicated direct detection techniques. The first technique is based on stacks of nucleartrack detectors with surface area ~18m2, sensitive to particle ionisation exceeding a high threshold. These detectors are analysed offline by optical scanning microscopes. The second technique is based on the trapping of charged particles in an array of roughly 800 kg of aluminium samples. These samples are monitored offline for the presence of trapped magnetic charge at a remote superconducting magnetometer facility. We present here the results of a search for magnetic monopoles using a 160 kg prototype MoEDAL trapping detector exposed to 8TeV proton-proton collisions at the LHC, for an integrated luminosity of 0.75 fb–1. No magnetic charge exceeding 0:5gD (where gD is the Dirac magnetic charge) is measured in any of the exposed samples, allowing limits to be placed on monopole production in the mass range 100 GeV≤ m ≤ 3500 GeV. Model-independent cross-section limits are presented in fiducial regions of monopole energy and direction for 1gDu2009≤u2009|g|u2009≤u20096gD, and model-dependent cross-section limits are obtained for Drell-Yan pair production of spin-1/2 and spin-0 monopoles for 1gDu2009≤u2009|g|u2009≤u20094gD. Under the assumption of Drell-Yan cross sections, mass limits are derived for |g|u2009=u20092gD and |g|u2009=u20093gD for the first time at the LHC, surpassing the results from previous collider experiments.

KNO scaling violations and the appearance of the three gluon coupling at the collider

Abstract KNO scaling violations are discussed in a soft gluon bremsstrahlung model for particle production with quarks as well as gluons as their sources. Both ISR and recent collider data can be reasonably accounted for in this scheme.

Large transverse momentum W production at Hadron colliders

Abstract Motivated by the recent observations of events in which a large transverse momentum W has been produced together with two energetic jets at the CERN proton—antiproton collider, we consider standard model processes in which a W is created in association with a second weak boson which then decays hadronically into two jets. We find that the production and decay of heavy quark—antiquark pairs can give rise to an observable number of (WW) events in existing collider data samples if the heavy-quark mass is close to the W mass. We calculate the expected event rates for proton—antiproton colliders operating in the energy range 0.6–2.0 TeV, and discuss the kinematic properties of the events, and the identity of the heavy quark Q which could be either the top quark, or a down-type quark from a new (fourth) generation.

How to test lepton number conservation at accelerators

Abstract It is shown that one-loop correction to the vωe and v ωe cross section for Dirac neutrinos, in the standard SU (2)L×U(1) model, are close to being measurable with existing neutrino beams. The correction, for the vector part, vanishes for Majorana neutrinos. Therefore an improvement of a factor two in the precision of the measurement of neutrino scattering cross section could provide evidence of an eventual violation of the conservation of lepton number.

Search for magnetic monopoles with the MoEDAL forward trapping detector in 2.11 fb−1 of 13 TeV proton–proton collisions at the LHC

Abstract We update our previous search for trapped magnetic monopoles in LHC Run 2 using nearly six times more integrated luminosity and including additional models for the interpretation of the data. The MoEDAL forward trapping detector, comprising 222 kg of aluminium samples, was exposed to 2.11 fb−1 of 13 TeV proton–proton collisions near the LHCb interaction point and analysed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges equal to the Dirac charge or above are excluded in all samples. The results are interpreted in Drell–Yan production models for monopoles with spins 0, 1/2 and 1: in addition to standard point-like couplings, we also consider couplings with momentum-dependent form factors. The search provides the best current laboratory constraints for monopoles with magnetic charges ranging from two to five times the Dirac charge.

The resonant time-like Kaon form factor

Abstract The K-form factor is analyzed in terms of a family of vector mesons whose couplings are determined through our earlier model for the pion form factor. Radiative corrections are applied. The model reproduces the data quite well. For the charge radius we obtain r K = 0.56 F to be compared with r K = (0.54 ± 0.14) F given by the Chou-Yang model.