Neutrino Experiments at the Large Hadron Collider

Electromagnetic processes at the LHC : nuclear parton distributions from deep inelastic pair production and exclusive photoproduction of single W bosons

The Compact Muon Solenoid (CMS) experiment records data from proton-proton (pp) and heavy ion (Pb-Pb and Pb-p) collisions at the Large Hadron Collider (LHC) to search for physics beyond the Standard Model, test theories of supersymmetry (SUSY), and measure properties of known particles with higher precision. In 2025, the LHC will be upgraded to the High Luminosity LHC (HL-LHC), where the luminosity will be increased by a factor of 10. This will increase the number of pile-up collisions to 140-200 events per proton-proton bunch crossing, compared to the current 40 events per crossing (where each bunch crossing occurs every 25 ns). In order to fully exploit the sensitivity of the CMS experiment, the current detectors must be upgraded to mitigate the effects of the large number of pileup interactions expected in collisions at the HL-LHC. New capabilities, such as precision timing measurements in calorimetric devices and minimum ionizing detectors, have been shown to effectively mitigate the effects due to pileup, and are expected to benefit the overall physics reach of the experiment. In addition to mitigating pileup and increasing the detector capabilities, precision timing is beneficial in the search for particles beyond the Standard Model. A simulation of a benchmark long lived neutralino SUSY search is presented, and it is shown that the generator particle flight times can be faithfully reconstructed using the detector-level information. Identification algorithms for the SUSY model have been significantly improved with the use of a Boosted Decision Tree, and it is demonstrated that this algorithm has many benefits as compared to cut based IDs. With use of the BDT for the long lived neutralino SUSY model, the background rejection is increased significantly, with constant signal acceptance of 53.6%. This is an improvement in the significance of the signal selection by a factor of 2.38. Further improvement is seen with the inclusion of detector timing information in the BDT – with this contributing ≈25% of the information used in signal event identification. We thus demonstrate that with the BDT, the SUSY neutralino search can be performed with increased signal identification significance, and the searches’ sensitivity is expected to improve with the time resolution attained by the upgraded CMS calorimeter.

The first run of the Large Hadron Collider (LHC) was completed by the end of 2012. It amazingly unveiled the mystery of electroweak symmetry breaking by discovering the Higgs scalar particle. Our workshop discussed the status of theoretical ideas and their comparison with the first LHC run, starting from the experimental data, followed by theoretical models and their ultraviolet completion. The purpose was to bring together leading Beyond the Standard Model researchers, field and string theory experts with a key interest in comparing various Beyond the Standard Model ideas with the existing LHC data. This stimulated an intense and fruitful interaction between these communities in the excellent environment provided by the Galileo Galilei Institute.

The question of physics beyond the Standard Model remains as crucial as it was before the discovery of a Higgs boson at the Large Hadron Collider, as the theoretical and experimental shortcomings of the Standard Model remain unresolved. Indeed, theoretical problems such as the hierarchy of energy scales, the Higgs mass fine-tuning and the large number of postulated parameters need to be addressed, while the experimental observations of dark matter, dark energy and neutrino masses are not explained by the Standard Model. Many hypotheses addressing these issues predict the existence of new neutral high-mass resonances decaying into muon pairs. This dissertation documents a search for this process using 25.5 inverse femtobarns of proton-proton collision data collected by the ATLAS experiment in Run‑I of the Large Hadron Collider. After evaluating the performance of the detector for reconstructing muons at very high momentum, the event yields observed as a function of the invariant mass of muon pairs are compared with expected values from Standard Model processes. The observed yields are found to be in good agreement with Standard Model predictions, and no significant excess of events is found. New gauge bosons with couplings to fermions equal to these of the Standard Model Z boson and with masses lower than 2.53 TeV are therefore excluded at 95% confidence level. A statistical combination with the results of the search for the same particle decaying into electron pairs yields a lower mass limit of 2.90 TeV at 95% confidence level. Limits are also placed in the context of two classes of models inspired by Grand Unification Theories: gauge theories with the $E_6$ symmetry group, as well as Minimal Z' Models.

The standard model in particle physics is such a successful model, which agrees well with almost all experimental tests in the past more than 20 years. However, there is large hope that new physics beyond the standard model would show up in the Large Hadron Collider (LHC). Meanwhile, many direct and indirect dark matter searches have shown signs of potential signals. If con¯rmed, the properties of the most mysterious but dominant part of matter constitute will be unveiled soon. In this thesis, we mainly have three sections. First, we will talk in detail about LHC phenomenology. This includes several topics, recovering particle masses from missing energy signatures with displaced tracks, diagnosing the top-quark angular asymmetry using LHC in- trinsic charge asymmetries, signature searches, including multi-lepton and diphoton searches, in the early LHC. After collider phenomenology, we will discuss a study for dark matter, which is focused on the indirect search, i.e. gamma ray spectra from dark matter annihilation and decay. And in the last section, we will cover several topics about some studies on formal side of physics, including metastable spontaneous SUSY breaking in a landscape of fuzzy droplets, entropic force and its °uctuation from gauge/gravity duality.

In this lecture we shall briefly review some motivations for physics beyond the Standard Model. We focus our attention on the hierarchy problem and discuss the role of gravity in defining and solving this problem.

Recent progress in low energy neutrino scattering physics and its implications for the standard and beyond the standard model physics

"Neutrino physics is largely an art of learning a great deal by observing nothing" (Haim Harari, 1988) was our general understanding of the field for the ~25 years previous. A new neutrino era was abruptly brought from outer space by a burst of SN1987A neutrinos. The detection of neutrinos from SN1987A gave a new impetus to neutrino research. As we know, new discoveries of neutrinos have since been made. Neutrinos were no longer mysterious, but attained particle citizenship.Giant liquid argon charge imaging experiments have the prospect of opening the door to the second new era in neutrino physics. The coming era would provoke not evolution, but revolution in particle physics. However, paving the way for the new era requires not evolutionary, but revolutionary detector developments. I hope this workshop will be conducive to reaping a rich harvest from its activities.In 1993, Professor Carlo Rubbia presented "The Renaissance of Experimental Neutrino Physics" in which he discussed various possibilities of shooting neutrino beams from CERN towards Gran Sasso, Super-Kamiokande at Kamioka and DUMAND in Hawaii. Now KEK hopes to shoot neutrino beams from J-PARC to Kamioka, Okinoshima, Korea and Gran Sasso. Atsuto Suzuki Director General, KEK J-PARC has moved into a new phase of operation. The commissioning of the accelerator complex and experiment facilities has begun, and it is urgent to attain initial design performance as soon as possible. For the immediate future, KEK has a 5 year plan. The plan includes the upgrade of the J-PARC accelerator to a multi-Mega-Watt facility, and detector R&Ds to form the basis for a next step in the neutrino experiment. One of the main issues of the future neutrino experiment will be the search for CP violation in neutrino oscillation, which demands much more precision than studying neutrino oscillation or non-zero theta13. This naturally requires a very massive detector with higher precision than presently available technologies. In addition, such a detector will also be an excellent detector for the further search for proton decay.The sensitivity of the various methods of extracting CP violation should be carefully evaluated. At the 4th International Workshop on Nuclear and Particle Phyics at J-PARC (NP08) in March 2008, the J-PARC MR power upgrade and the future neutrino experiment were discussed.At the workshop, a comparison of first and second maximum in electron neutrino appearance in muon neutrino beam was discussed. This method is free from systematic errors due to ambiguities of neutrino and anti-neutrino cross sections. On the other hand, this method requires a very massive detector with energy reconstruction capability for a wide range of neutrino energy. Beside the statistical precision, which requires a high power proton accelerator, there are many strict requirements on the detector. Most of the requirements are common to a detector for neutrino physics and to the search for proton decay.We need new ways of looking for new phenomena at a level far beyond on-going experiments. Future experiments should be designed based on new detector technology, improved accelerator technology and the results of present on-going experiments.We are looking forward seeing the outcome. Koichiro Nishikawa Director, IPNS KEK

The surprising discovery of the X(3872) resonance by the Belle experiment in 2003, and subsequent confirmation by BaBar, CDF and D0, opened up a new chapter of QCD studies and puzzles. Since then, detailed experimental and theoretical studies have been performed in attempt to determine and explain the proprieties of this state. Since the end of 2009 the world’s largest and highest-energy particle accelerator, the Large Hadron Collider (LHC), started its operations at the CERN laboratories in Geneva. One of the main experiments at LHC is CMS (Compact Muon Solenoid), a general purpose detector projected to address a wide range of physical phenomena, in particular the search of the Higgs boson, the only still unconfirmed element of the Standard Model (SM) of particle interactions and, new physics beyond the SM itself. Even if CMS has been designed to study high energy events, it’s high resolution central tracker and superior muon spectrometer made it an optimal tool to study the X(3872) state. In this thesis are presented the results of a series of study on the X(3872) state performed with the CMS experiment. Already with the first year worth of data, a clear peak for the X(3872) has been identified, and the measurement of the cross section ratio with respect to the Psi(2S) has been performed. With the increased statistic collected during 2011 it has been possible to study, in bins of transverse momentum, the cross section ratio between X(3872) and Psi(2S) and separate their prompt and non-prompt component.

In this review we do not try to cover all the aspects of physics beyond the standard model (BSM), instead our latest understanding on the BSM will be presented: i) The Higgs sector is likely related to BSM, which can be confirmed at current running large hadron collider (LHC) or the future colliders. Furthermore we pointed out that spontaneous CP violation can be closely related to the lightness of the Higgs boson. ii) Top quark forward-backward asymmetry, which was measured by Tevatron, might be the sign of BSM. We proposed a new color-octet particle ZC to account for the observation and ZC can be further studied at the LHC. iii) If dark matter (DM) is utilized to accommodate astrophysical observations, it ought to be observed at the high energy LHC and DM produced at colliders should be the smoking gun signal. iv) Lithium puzzle might also be the sign of the BSM. We briefly review the newly proposed solution to Lithium puzzle, i.e., the existence of non-thermal component during the big bang nuclei-synthesis (BBN). The possible origins of the non-thermal component can be dark matter or the new accelerating mechanism of normal particles.

Over the years both theoretical as well as experimental evidence has accumulated that strongly suggests the existence of physics beyond the current standard model of particle physics (SM). The Large Hadron Collider currently starting up at CERN will test many of the ideas for such physics beyond the standard model (BSM) and hopefully will provide us with a wealth of new information. In this note we argue that there is also a very good motivation to search for new physics in low energy experiments that can provide us with powerful complementary information on currently open questions and in particular on how the standard model is embedded into a more fundamental theory. Let us begin by briefly repeating some of the main reasons why we believe that there must be physics beyond the standard model. On the theoretical side there are a number of deficiencies in the SM. Some of them could be just aesthetic defects but some may go deeper. First of all the SM has a relatively large number O(30) free parameters that cannot be determined from theory alone but must be measured experimentally. Although this does not indicate an inconsistency of the theory it certainly is not in line with the hope that a fundamental theory of everything should have very few, possibly only 1 or even 0, free parameters. Moreover, some of the parameters seemingly need to require an enormous degree of finetuning or appear unnaturally small. Well known examples are the Higgs mass but also the θ parameter of QCD (which must be extremely small in order not to be in conflict with the observed smallness of strong CP violation). Another dissatisfying feature is that gravity is not incorporated into the SM but rather treated as a separate part. This is not just an aesthetic defect but also an expression of the fact that the quantization of gravity is still not (fully) understood. Finally, strictly speaking the SM will most likely not be valid up to arbitrary high energy scales. On the one hand this is due to our current inability to properly quantize gravity. But even the non-gravity parts are probably encountering problems in the form of Landau poles (places where the coupling becomes infinite) in the QED sector (at a very high scale much beyond the Planck scale) but probably also in the Higgs sector (where the problem is much more immediate and will occur at scales much below the Planck scale -

The strangeness production ratios [bar wedge]/∧ and [bar wedge]/K0S are measured by the LHCb detector from 0.3 nb-1 of proton-proton collisions delivered by the Large Hadron Collider (LHC) at CERN with centre-of-mass energy √s = 0.9TeV and 1.8 nb-1 at √s = 7TeV. Both ratios are presented as a function of transverse momentum, pT, and rapidity, y, in the ranges 0.15 < pT < 2.50 GeV/c and 2.0 < y < 4.5. The ratios measured at the two energies are in good agreement in an overlapping region of rapidity loss, Δ y = ybeam - y, and are consistent with previous measurements. A review of the Standard Model is presented with emphasis on the diffculties in its application for predictions of physics at the LHC. Phenomenological models are introduced as the current state of the art for such predictions. Accurate models are required as an essential benchmark for future discoveries of physics beyond the Standard Model. LHCb's results represent a powerful test for these models in the soft QCD regime for processes including hadronisation. The ratio [bar wedge]/∧, measuring the transport of baryon number from the collision into the detector, is smaller in data than predicted, particularly at high rapidity. The ratio [bar wedge]/K0 S, measuring the baryon-to-meson suppression in strange quark hadronisation, is significantly larger than expected. The LHCb experiment is introduced, with particular focus on its Ring Imaging Cherenkov (RICH) detectors. The development and successful implementation of a method to align those RICH detectors is presented, using proton-proton collision data from the early running period of the Large Hadron Collider, which began in November 2009. The performance of the RICH detectors is investigated with preliminary analysis of the Cherenkov photon yield. The RICH mirror positions are monitored using an automated software control system, which has been running successfully since October 2008.

With the advent of a new generation of neutrino experiments which leverage high-intensity neutrino beams for precision measurements, it is timely to explore physics topics beyond the standard neutrino-related physics. Given that the realm of beyond the standard model (BSM) physics has been mostly sought at high-energy regimes at colliders, such as the LHC at CERN, the exploration of BSM physics in neutrino experiments will enable complementary measurements at the energy regimes that balance that of the LHC. This is in concert with new ideas for high-intensity beams for fixed target and beam-dump experiments world-wide, e.g., those at CERN. The combination of the high intensity proton beam facilities and massive detectors for precision neutrino oscillation parameter measurements and for CP violation phase measurements will help make BSM physics reachable even in low energy regimes in accelerator based experiments. Large mass detectors with highly precise tracking and energy measurements, excellent timing resolution, and low energy thresholds will enable searches for BSM phenomena from cosmogenic origin, as well. Therefore, it is conceivable that BSM topics in the next generation neutrino experiments could be the dominant physics topics in the foreseeable future, as the precision of the neutrino oscillation parameter and CPV measurements continues to improve. In this spirit, this white paper provides a review of the current landscape of BSM theory in neutrino experiments in two selected areas of the BSM topics - dark matter and neutrino related BSM - and summarizes the current results from existing neutrino experiments to set benchmarks for both theory and experiment. This paper then provides a review of upcoming neutrino experiments throughout the next 10 - 15 year time scale and their capabilities to set the foundation for potential reach in BSM physics in the two aforementioned themes.

The production of particle jets will be the dominant process at the Large Hadron Collider (LHC), and jets will thus be the signal or define the environment of many analyses at the ATLAS experiment. Their precise measurement is a vital requirement for many potential discoveries of new physics beyond the Standard Model. The first part of this thesis introduces a new method to constrain and correct errors of the energy measurement of jets in the TeV regime. The emphasis is on a very high reach in transverse jet momenta even with earliest ATLAS data. This is achievable by an intercalibration utilizing the large inclusive jet production cross section. In the second part inclusive jet measurements are used to probe the validity of Quantum Chromodynamics (QCD). Several analyses are presented and their sensitivity is estimated using simulated data of an effective theory of a possible quark substructure. The search is then extended to effects of quantum gravity that could emerge at the LHC in scenarios of new physics, demonstrating that inclusive jet measurements are a powerful tool to probe QCD and a broad range of new physics models.

We present a brief overview of the physics potential of the Large Hadron Collider (LHC) and the role of quantum chromody- namics (QCD) in predicting various observables at the LHC with unprecedented accuracy. We have studied the production of Standard Model (SM) Higgs boson through gluon fusion channel and various signals of physics beyond the Standard Model (BSM) restricted to non-supersymmetric scenarios. These are models with large extra-dimensions such as ADD and Randall- Sundrum models and also physics senario resulting from scale/conformal invariant sector, namely unparticle physics. We have presented QCD effects to several of the observables in these models through higher order perturbative QCD corrections and parton distribution functions. We have demonstrated how the these corrections reduce the scale ambiguities coming from renormalisation and factorisation. Our study shows that the precise and unambiguous predictions are possible for various BSM studies at the LHC.