Narrow Results

Top quarks are copiously produced at the LHC. The measurements are in stage for precision. A review on top-quark properties measured by the ATLAS, CMS and LHCb collaborations is presented, including the mass of the top quark, coupling, production cross sections and decay properties.

Nuclear-structure theory is an important ingredient in the interpretation of many experiments that look for physics beyond the Standard Model. I review the role of nuclear structure in attempts to to learn more about neutrinos through double beta-decay and to discover new sources of CP violation through atomic electric-dipole moments.

I discuss low energy searches for new physics beyond the Standard Model, identifying the role played by chiral symmetries in these searches and in various new physics scenarios. I focus in particular on electric dipole moment searches; precision studies of weak decays and electron scattering; and neutrino properties and interactions.

Progress in Lattice QCD is slow, but steady. In this talk I shall review recent advances, both technical and numerical, and assess the present state of numerical simulations.

The current status of the muon anomalous magnetic moment is discussed. The leading order hadronic contribution is reevaluated based on the new data on e⁺e^- annihilation. The experimental value is about 3.3 standard deviations higher than the Standard Model prediction.

The LHC will be a W and Z factory. At nominal low luminosity of L = 10³³cm^-2s^-1 approx 15 W → lν events and 1.5 Z→ll, l = μ,e events will be produced per second. These processes will be important to test the Standard Model via precision measurements. W and Z production represent backgrounds to other Standard Model processes and signals of new physics and thus need to be understood precisely in the new kinematic region available at the LHC. In addition, they will be crucial physics channels to understand the detectors and its performances at start-up.

Precision tests of the Standard Model are performed using electroweak measurements. An overview is provided of preliminary and recently published data, including final results from LEPI and updated W mass and top mass measurements. A comparison between measurements and theoretical expectations is presented and the Standard Model free parameters are constrained within the context of the model. Notably, the mass of the Higgs boson is found from the electroweak fit to be less than 166 GeV/c² at the 95% confidence level limit.

The status of the Unitarity Triangle analysis performed by the UTfit Collaboration is presented. The most recent determinations of theoretical and experimental parameters are used with the aim of over-constraining the apex of the Unitarity Triangle in the Standard Model. The results and the plots presented in this paper can be found at the URL http://www.utfit.org, where they are continuously updated.

This paper consists of three separate articles on the number of fundamental dimensionful constants in physics. We started our debate in summer 1992 on the terrace of the famous CERN cafeteria. In the summer of 2001 we returned to the subject to find that our views still diverged and decided to explain our current positions. LBO develops the traditional approach with three constants, GV argues in favor of at most two (within superstring theory), while MJD advocates zero.

I define a naturalness criterion formalizing the intuitive notion of naturalness discussed in the literature. After that, using ϕ⁴ as an example, I demonstrate that a theory may be natural in the MS-scheme and, at the same time, unnatural in the Gell-Mann–Low scheme. Finally, I discuss the prospects of using a version of the Gell-Mann–Low scheme in the Standard Model.

Having significantly interacted over 17 years with Abdus Salam, as an undergraduate, postgraduate, postdoc, and eventually as an academic colleague, I will try to paint a personal picture of Salam which may convey something about the man, his greatness and his humanity…

After the last missing piece, the Higgs particle, has probably been identified, the Standard Model of the subatomic particles appears to be a quite robust structure, that can survive on its own for a long time to come. Most researchers expect considerable modifications and improvements to come in the near future, but it could also be that the Model will stay essentially as it is. This, however, would also require a change in our thinking, and the question remains whether and how it can be reconciled with our desire for our theories to be “natural”.

The charge given to me by the organisers of the memorial meeting for Prof. Abdus Salam’s 90th birthday is to recall my personal impressions of him and review an aspect of the standard model (SM) physics related to my work. Salam was, first and foremost, a brilliant theoretical physicist whose work is still very much en vogue, currently being tested precisely by the experiments at the Large Hadron Collider (LHC). Salam was, however, equally effective as a scientific advisor to many institutions, such as IAEA and CERN, but also to the government of Pakistan as the chief scientific strategist. He was also an untiring advocate of scientific research and higher education in developing countries, which took a concrete form in the International Centre for Theoretical Physics (ICTP) in Trieste. I discuss these aspects of his scientific life seen from my perspective in the first part. In the second part of my talk, which may appear as a disjoint piece to the first, I summarise some selected topics in rare B-decays — the current flavour physics frontier. Experiments carried out over several decades are largely in agreement with the SM, thanks also to dedicated theoretical effort in their interpretation. However, this field is undergoing an anomalous phase in a number of key measurements, in particular reported by LHCb, triggering a very lively debate and model building. These anomalies, which I review here, are too numerous to be ignored, but none is individually significant enough to announce a breakdown of the SM.

Since 2010 there has been a rich harvest of results on standard model physics by the ATLAS and CMS experiments operating on the Large Hadron Collider. In the summer of 2012, a spectacular discovery was made by these experiments of a new, heavy particle. All the subsequently analysed data point strongly to the properties of this particle as those expected for the Higgs boson associated with the Brout–Englert–Higgs mechanism postulated to explain the spontaneous symmetry breaking in the electroweak sector, thereby explaining how elementary particles acquire mass. This article focuses on the CMS experiment, the technological challenges encountered in its construction, describing some of the physics results obtained so far, including the discovery of the Higgs boson, and searches for the widely anticipated new physics beyond the standard model, and peer into the future involving the high-luminosity phase of the LHC. This article is complementary to the one by Peter Jenni that focuses on the ATLAS experiment.

The journey in search for the Higgs boson with the ATLAS and CMS experiments at the Large Hadron Collider (LHC) at CERN started more than two decades ago. But the first discussions motivating the LHC project dream date back even further into the 1980s. This article will recall some of these early historical considerations, mention some of the LHC machine milestones and achievements, focus as an example of a technological challenge on the unique ATLAS superconducting magnet system, and then give an account of the physics results so far, leading to, and featuring particularly, the Higgs boson results, and sketching finally prospects for the future. With its emphasis on the ATLAS experiment it is complementary to the preceding article by Tejinder S. Virdee which focused on the CMS experiment.

Experimental era of rare B-decays started with the measurement of B → K^*γ by CLEO in 1993, followed by the measurement of the inclusive decay B → X_sγ in 1995, which serves as the standard candle in this field. The frontier has moved in the meanwhile to the experiments at the LHC, in particular, LHCb, with the decay B⁰ → μ⁺μ⁻ at about 1 part in 1010 being the smallest branching fraction measured so far. Experimental precision achieved in this area has put the standard model to unprecedented stringent tests and more are in the offing in the near future. I review some key measurements in radiative, semileptonic and leptonic rare B-decays, contrast them with their estimates in the SM, and focus on several mismatches reported recently. They are too numerous to be ignored, yet, standing alone, none of them is significant enough to warrant the breakdown of the SM. Rare B-decays find themselves at the crossroads, possibly pointing to new horizons, but quite likely requiring an improved theoretical description in the context of the SM. An independent precision experiment such as Belle II may help greatly in clearing some of the current experimental issues.

The ATLAS and CMS collaborations have performed studies of a wide range of Standard Model processes using data collected at the Large Hadron Collider at center-of-mass energies of 7, 8 and 13 TeV. These measurements are used to explore the Standard Model in a new kinematic regime, perform precision tests of the model, determine some of its fundamental parameters, constrain the proton parton distribution functions, and study new rare processes observed for the first time. Examples of recent Standard Model measurements performed by the ATLAS and CMS collaborations are summarized in this report. The measurements presented span a wide range of event final states including jets, photons, W/Z bosons, top quarks, and Higgs bosons.

Certificateless public key cryptography is an attractive paradigm which combines advantages of both traditional public key cryptography and identity-based cryptography because it avoids using certificates and does not suffer from key escrow. In this paper, the author proposed a certificateless signature (CLS) scheme built upon bilinear pairings and proved its security in the standard model. The schemeturns out to be more efficient than other proposed CLS schemes in the standard model, and the signin algorithm needs no pairing operation while the reverse operation requires only three pairing computations.

Gerry Brown was a godfather of our hidden local symmetry (HLS) for the vector meson from the birth of the theory throughout his life. The HLS is originated from very nature of the nonlinear realization of the symmetry $G$ based on the manifold $G/H$, and thus is universal to any physics based on the nonlinear realization. Here, I focus on the Higgs Lagrangian of the Standard Model (SM), which is shown to be equivalent to the nonlinear sigma model based on $G/H=\mathrm{\text{SU}}{(2)}_L\times \mathrm{\text{SU}}{(2)}_R/\mathrm{\text{SU}}{(2)}_V$ with additional symmetry, the nonlinearly-realized scale symmetry. Then, the SM does have a dynamical gauge boson of the SU${(2)}_V$ HLS, “SM $\rho$ meson”, in addition to the Higgs as a pseudo-dilaton as well as the NG bosons to be absorbed in to the $W$ and $Z$. Based on the recent work done with Matsuzaki and Ohki, I discuss a novel possibility that the SM $\rho$ meson acquires kinetic term by the SM dynamics itself, which then stabilizes the skyrmion dormant in the SM as a viable candidate for the dark matter, what we call “dark SM skyrmion (DSMS)”.

We report on the Standard Model perturbative uncertainties in CP- and isospin-averaged branching ratio $B_{s\gamma }^{SM}$ of inclusive $\overline{B}$ → X_sγ process.