M. Pelliccioni

The design of a future multi-TeV muon collider needs new ideas to overcome the technological challenges related to muon production, cooling, accumulation and acceleration. In this paper a layout of a positron driven muon source known as the Low EMittance Muon Accelerator (LEMMA) concept is presented. The positron beam, stored in a ring with high energy acceptance and low emittance, is extracted and driven to a multi-target system, to produce muon pairs at threshold. This solution alleviates the issues related to the power deposited and the integrated Peak Energy Density Deposition (PEDD) on the targets. Muons produced in the multi-target system will then be accumulated before acceleration and injection in the collider. A multi-target line lattice has been designed to cope with the focusing of both the positron and muon beams. Studies on the number, material and thickness of the targets have been carried out. A general layout of the overall scheme and a description is presented, as well as plans for future R&D.

The muon collider represents one of the most promising solutions for a future machine exploring the high energy frontier, but several challenges due to the 2.2 $\mu$sec muon lifetime at rest have to be carefully considered. The LEMMA project is investigating the possibility of producing low emittance muon/antimuon pairs from the e$^+$e$^-$ annihilation process at threshold energy, resulting in small transverse emittance beams without any additional beam cooling. However most of the measurements available are performed at higher $\sqrt{s}$ values. It is therefore necessary to measure muons production in positron annihilation at threshold energy and compare the experimental results with the predictions in this specific energy regime. Apart from being a topic of physical interest by itself, these near to threshold measurements can have a sizeable impact on the estimation of the ultimate luminosity achievable in a muon collider with the LEMMA injection scheme.

This note describes the local reconstruction in the Drift Tube subdetector of the CMS muon subsystem. The local reconstruction is the sequence of steps leading from the TDC measurements to reconstructed three-dimensional segments inside each DT chamber. These segments are the input to the muon track reconstruction. This note updates and supersedes CMS NOTE 2002/043

This work introduces an experimental test of the new proposal for a low–emittance muon accelerator (LEMMA). A low–emittance muon beam is obtained from the e$^+$ e$^-$ → μ$^+$ μ$^-$ annihilation process at the threshold energy of 45 GeV eliminating the need for a dedicated muon cooling system. A series of two testbeam campaigns were carried out at CERN to validate this concept. The experimental setup is presented together with first preliminary results from the obtained data.

The investigation of the energy frontier in physics requires novel concepts for future colliders. The idea of a muon collider is very appealing since it would allow to study particle collisions at up to tens of TeV energy, while offering a cleaner experimental environment with respect to hadronic colliders. One key element in the muon collider design is the low-emittance muon production. Recently,the Low EMittance Muon Accelerator (LEMMA) collaboration has explored the muon pair production close to its kinematic threshold by annihilating 45 GeV positrons with electrons in a low Z material target. In this configuration, muons are emerging from the target with a naturally low-emittance. In this paper we describe the performance of a system, to study this production mechanism, that consists in several segmented absorbers with alternating active layers composed of fast Cherenkov detectors together with a muon identification technique based on this detector. Passive layers were made of tungsten. We collected data corresponding to muon and electron beams produced at the H2 line in the North Area of the European Organization for Nuclear Research (CERN) in September 2018.

1;2 is predicted. The ATLAS and CMS experiments reported in 2012 the observation of a new boson with a mass of about 125 GeV 3;4 . We refer to this newly observed Higgs boson as h(125) in this proceedings. While this boson shows SM-like properties, it is possible that it is merely part of a larger EW symmetry breaking sector. This can be accommodated in several extensions of the SM. In particular, we consider the scenario in which the SM Higgs boson mixes with a heavy EW singlet 6 . This scenario is also useful to construct a general modelization of the Higgs sector that allows to interpret the data for several possible Higgs sector congurations. Both ATLAS and CMS reported several searches for heavy SM-like Higgs bosons. In Ref. 4 , ATLAS excludes a SM-like heavy Higgs boson in the mass range of 131 < mH < 559 GeV at 95% CL. The CMS collaboration excluded an additional SM-like Higgs boson to to masses of 710 GeV at 95% CL 7 . None of the searches by ATLAS and CMS was performed using the full Run-1 LHC statistics collected by the collaborations. We report on an extension of the CMS search using the full Run-1 dataset. In addition to the previous CMS analysis, we interpreted the data in the scenario of the SM expanded by an additional EW singlet. Both the possible SM-like heavy Higgs boson and the EW singlet are indicated as H. The analysis is performed using the proton-proton collision data recorded by CMS 5 , corresponding to integrated luminosities of up to 5.1 fb 1 at p s = 7 TeV and up to 19.7 fb 1 at p s = 8 TeV. The search is conducted in the 145 < mH < 1000 GeV mass range, exploiting both the H! ZZ and the H! WW decay channels, which are the most sensitive to high mass Higgs boson decays. The lower boundary of the search is chosen to limit the contamination of h(125). In the H! ZZ decays, we consider the nal states containing four

The muon collider represents one of the most promising solutions for a future machine exploring the high energy frontier, but several challenges due to the 2.2 $\mu$sec muon lifetime at rest have to be carefully considered. The LEMMA project is investigating the possibility of producing low emittance muon/antimuon pairs from the e$^+$e$^-$ annihilation process at threshold energy, resulting in small transverse emittance beams without any additional beam cooling. However most of the measurements available are performed at higher $\sqrt{s}$ values. It is therefore necessary to measure muons production in positron annihilation at threshold energy and compare the experimental results with the predictions in this specific energy regime. Apart from being a topic of physical interest by itself, these near to threshold measurements can have a sizeable impact on the estimation of the ultimate luminosity achievable in a muon collider with the LEMMA injection scheme.

This work introduces a new proposal for a low--emittance muon accelerator (LEMMA) in which muon beam is obtained from the e$^+$e$^-\rightarrow\mu^+\mu^-$ annihilation process with positrons at the threshold energy of 45 GeV. The experimental test beam setup implemented to validate this concept is presented together with preliminary results from the experimental data.

A search for the decay of a heavy Higgs boson in the H$\to$ZZ and H$\to$WW channels is reported, analyzing several final states of the H$\to$ZZ and H$\to$WW decays. The search used proton-proton collision data corresponding to an integrated luminosity of up to 5.1 fb$^{-1}$ at $\sqrt{s} = 7$ TeV and up to 19.7 fb$^{-1}$ at $\sqrt{s} = 8$ TeV recorded with the CMS experiment at the CERN LHC. A Higgs boson with Standard Model-like coupling and decays in the mass range of 145 $< m_H <$ 1000 GeV is excluded at 95\% confidence level, based on the limit on the product of cross section and branching fraction. An interpretation of the results in the context of an electroweak singlet extension of the standard model is reported.

Flavor mixing of neutral mesons is a long and well known phenomenon in particle physics. Experimental evidence of mixing of the neutral kaon was obtained in 1956, followed in 1987 by the evidence of Bd mixing. In 1974, A. Pais and S. B. Treiman firstly introduced the idea of charm mixing and CP violation. Even though many searches were conducted over time, it was clear that the small scale at which both amplitude and frequency of the oscillation took place made any possible observation challenging. In 2007, both the BABAR and Belle experiments announced the first evidence of mixing in the charm sector. The analyses concerned the study of a two body decay of the D0 meson. Few months later, BABAR presented the analysis of the decay D0 → K+π-π0 . This is the main topic of this thesis.

Neutral meson flavor oscillations have been observed and studied for strange and bottom quark systems. They have had the utmost importance to understand the nature of weak interactions of elementary particles, especially in connection with the Cabibbo-Kobayashi-Maskawa mechanism. In this review we summarize the status of the experimental investigation of the D0 meson flavor mixing, that was the last to be discovered few years ago in 2007. A review of the general formalism and a summary of the theoretical predictions is given before reviewing the experimental techniques and the combined results. Future developments of such research are listed in view of experimental facilities able to produced several tens of billion of D0 mesons.

A search for a Higgs boson in the decay channel ${\rm H} \rightarrow {\rm ZZ}^{(*)}$ with each Z boson decaying to an electron or muon pair is presented using pp collisions from the LHC at $\sqrt s$ = 7 TeV. The data analyzed correspond to an integrated luminosity of $1.13 \pm 0.07$ fb$^{-1}$ recorded by the CMS detector in 2010 and 2011. The search covers Higgs boson mass ($m_{\rm H}$) hypotheses of $110 < m_{\rm H} < 600 \GeVcc$. Fifteen events are observed, while $14.4 \pm 0.6$ events are expected from standard model background processes. Upper limits at 95% CL on the cross section$\times$branching ratio for a Higgs boson with standard model-like decays exclude cross sections from about one to two times the expected standard model cross section for masses in the range $180 < m_{\rm H} < 420 \GeVcc$. Reinterpreted in the context of the standard model with four fermion families a Higgs boson with a mass in the range 138 -162 $\GeVcc$ and 178-502 $\GeVcc$ is excluded at 95% CL.

A search for a Higgs boson in the decay channel ${\rm H} \rightarrow {\rm ZZ}^{(*)}$ with each Z boson decaying to an electron or muon pair is presented using pp collisions from the LHC at $\sqrt s$ = 7 TeV. The data analyzed correspond to an integrated luminosity of $1.13 \pm 0.07$ fb$^{-1}$ recorded by the CMS detector in 2010 and 2011. The search covers Higgs boson mass ($m_{\rm H}$) hypotheses of $110 < m_{\rm H} < 600 \GeVcc$. Fifteen events are observed, while $14.4 \pm 0.6$ events are expected from standard model background processes. Upper limits at 95% CL on the cross section$\times$branching ratio for a Higgs boson with standard model-like decays exclude cross sections from about one to two times the expected standard model cross section for masses in the range $180 < m_{\rm H} < 420 \GeVcc$. Reinterpreted in the context of the standard model with four fermion families a Higgs boson with a mass in the range 138 -162 $\GeVcc$ and 178-502 $\GeVcc$ is excluded at 95% CL.

I. INTRODUCTION The e+e- @-factory DAQNJZ is presently under construction in Frascati. It is designed as a double ring system with a maximum number of 120 bunches/beam. The short term luminosity goal is L=1.3 1032cm-2sec-1 with 30 bunches. The strategy, adopted to achieve such a luminosity, is common to many factory designs : high current, many bunches and separate rings. The technical problems are complicated by the relatively low energy of the beams. A general overview of the project and the most significant technical solutions adopted for The construction of DAQNE in the Frascati National Laboratories (LNF), has been approved and fully funded by the National Institute of Nuclear Physics (INFN) in June 1990, while the engineering design phase has started in January 1991.

We summarise the recent results on neutral heavy Higgs searches in the di-bosonDi-boson final state using 13 TeV data set collected by the CMS in 2015 and 2016. The search mainly targets for a scalar search where gluon-fusion and vector boson fusionVector boson fusion (VBF) production hypothesis are considered. Search strategy covers a mass range from few hundred Gev to TeV level by testing narrow and wide-width hypotheses.