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J. Zupan

Publications and source records attributed to J. Zupan.

At least 19 recordsLinked to original sources
arXiv2024

Workshop summary -- Kaons@CERN 2023

Kaon physics is at a turning point -- while the rare-kaon experiments NA62 and KOTO are in full swing, the end of their lifetime is approaching and the future experimental landscape needs to be defined. With HIKE, KOTO-II and LHCb-Phase-II on the table and under scrutiny, it is a very good moment in time to take stock and contemplate about the opportunities these experiments and theoretical developments provide for particle physics in the coming decade and beyond. This paper provides a compact summary of talks and discussions from the Kaons@CERN 2023 workshop.

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arXiv2023

Post-LS3 Experimental Options in ECN3

The Experimental Cavern North 3 (ECN3) is an underground experimental cavern on the CERN Prévessin site. ECN3 currently hosts the NA62 experiment, with a physics programme devoted to rare kaon decays and searches of hidden particles approved until Long Shutdown 3 (LS3). Several options are proposed on the longer term in order to make best use of the worldwide unique potential of the high-intensity/high-energy proton beam extracted from the Super Proton Synchrotron (SPS) in ECN3. The current status of their study by the CERN Physics Beyond Colliders (PBC) Study Group is presented, including considerations on beam requirements and upgrades, detector R&D and construction, schedules and cost, as well as physics potential within the CERN and worldwide landscape.

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arXiv2019

The Belle II Physics Book

We present the physics program of the Belle II experiment, located on the intensity frontier SuperKEKB $e^+e^-$ collider. Belle II collected its first collisions in 2018, and is expected to operate for the next decade. It is anticipated to collect 50/ab of collision data over its lifetime. This book is the outcome of a joint effort of Belle II collaborators and theorists through the Belle II theory interface platform (B2TiP), an effort that commenced in 2014. The aim of B2TiP was to elucidate the potential impacts of the Belle II program, which includes a wide scope of physics topics: B physics, charm, tau, quarkonium, electroweak precision measurements and dark sector searches. It is composed of nine working groups (WGs), which are coordinated by teams of theorist and experimentalists conveners: Semileptonic and leptonic B decays, Radiative and Electroweak penguins, phi_1 and phi_2 (time-dependent CP violation) measurements, phi_3 measurements, Charmless hadronic B decay, Charm, Quarkonium(like), tau and low-multiplicity processes, new physics and global fit analyses. This book highlights "golden- and silver-channels", i.e. those that would have the highest potential impact in the field. Theorists scrutinised the role of those measurements and estimated the respective theoretical uncertainties, achievable now as well as prospects for the future. Experimentalists investigated the expected improvements with the large dataset expected from Belle II, taking into account improved performance from the upgraded detector.

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arXiv2019

The CLIC Potential for New Physics

The Compact Linear Collider (CLIC) is a mature option for the future of high energy physics. It combines the benefits of the clean environment of $e^+e^-$ colliders with operation at high centre-of-mass energies, allowing to probe scales beyond the reach of the Large Hadron Collider (LHC) for many scenarios of new physics. This places the CLIC project at a privileged spot in between the precision and energy frontiers, with capabilities that will significantly extend knowledge on both fronts at the end of the LHC era. In this report we review and revisit the potential of CLIC to search, directly and indirectly, for physics beyond the Standard Model.

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arXiv2019

Opportunities in Flavour Physics at the HL-LHC and HE-LHC

Motivated by the success of the flavour physics programme carried out over the last decade at the Large Hadron Collider (LHC), we characterize in detail the physics potential of its High-Luminosity and High-Energy upgrades in this domain of physics. We document the extraordinary breadth of the HL/HE-LHC programme enabled by a putative Upgrade II of the dedicated flavour physics experiment LHCb and the evolution of the established flavour physics role of the ATLAS and CMS general purpose experiments. We connect the dedicated flavour physics programme to studies of the top quark, Higgs boson, and direct high-$p_T$ searches for new particles and force carriers. We discuss the complementarity of their discovery potential for physics beyond the Standard Model, affirming the necessity to fully exploit the LHC's flavour physics potential throughout its upgrade eras.

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arXiv2015

The Physics of the B Factories

This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C. Please note that version 3 on the archive is the auxiliary version of the Physics of the B Factories book. This uses the notation alpha, beta, gamma for the angles of the Unitarity Triangle. The nominal version uses the notation phi_1, phi_2 and phi_3. Please cite this work as Eur. Phys. J. C74 (2014) 3026.

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arXiv2013

Report of the Quark Flavor Physics Working Group

This report represents the response of the Intensity Frontier Quark Flavor Physics Working Group to the Snowmass charge. We summarize the current status of quark flavor physics and identify many exciting future opportunities for studying the properties of strange, charm, and bottom quarks. The ability of these studies to reveal the effects of new physics at high mass scales make them an essential ingredient in a well-balanced experimental particle physics program.

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arXiv2010

Physics at Super B Factory

This report presents the results of studies that investigate the physics reach at a Super $B$ factory, an asymmetric-energy $e^+e^-$ collider with a design luminosity of $8 \times 10^{35}$ cm$^{-2}$s$^{-1}$, which is around 50 times as large as the peak luminosity achieved by the KEKB collider. The studies focus on flavor physics and CP violation measurements that could be carried out in the LHC era. The physics motivation, key observables, measurement methods and expected precisions are presented.

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arXiv2006

Semi-inclusive hadronic B decays as null tests of the Standard Model

We propose a new set of observables that can be used as experimental null tests of the Standard Model in charged and neutral B decays. The CP asymmetries in hadronic decays of charged B mesons into inclusive final states containing at least one of the following mesons: K_{S,L}, eta', c\bar c bound states or neutral K^* or D mesons, for all of which a U-spin rotation is equivalent to a CP conjugation, are CKM suppressed and furthermore vanish in the exact U-spin limit. We show how this reduces the theoretical error by using Soft Collinear Effective Theory to calculate the CP asymmetries for K_{S,L} X_{s+d}, K^* X_{s+d} and eta' X_{s+d} final states in the endpoint region. For these CP asymmetries only the flavor and not the charge of the decaying B meson needs to be tagged up to corrections of NLO in 1/m_b, making the measurements more accessible experimentally.

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arXiv2006

Weak phase alpha from B^0-> a_1^{+-}(1260) pi^{-+}

Quasi two-body decays B^0(t)-> a_1^{+-}(1260) pi^{-+} identified by four charged pions determine a phase alpha_eff, which is equal to the weak phase alpha in the limit of vanishing penguin amplitudes. Applying flavor SU(3) to these decays and to B->a_1 K and B->K_1 pi, with K_1 an admixture of K_1(1270) and K_1(1400), we derive expressions providing bounds on alpha-alpha_{eff}. Higher precision in alpha may be achieved by an overall fit to a complete set of SU(3) related measurements. A method is sketched applying isospin symmetry to time-dependent invariant mass distributions in B->pi^+ pi^- pi^0 pi^0.

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arXiv2005

The Discovery Potential of a Super B Factory

The Proceedings of the 2003 SLAC Workshops on flavor physics with a high luminosity asymmetric e+e- collider. The sensitivity of flavor physics to physics beyond the Standard Model is addressed in detail, in the context of the improvement of experimental measurements and theoretical calculations.

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arXiv2005

Isospin-breaking effects on alpha extracted in B --> pi pi, rho rho, rho pi

Isospin-breaking in B --> pi pi caused by pi^0-eta-eta' mixing is studied in a model-independent way using flavor SU(3). Measured branching ratios for B^+ --> pi^+ pi^0, B^+ --> pi^+ eta^(') and B^0 --> pi^0 eta^(') imply an uncertainty in alpha smaller than 1.4 degree. We find a negligible effect of pi^0-eta-eta' mixing on alpha in B --> rho pi. Characterizing the effect of rho^0-omega mixing in B --> rho rho and in B --> rho pi by the two-pion invariant mass dependence, we point out a way of constraining this effect experimentally or eliminating it altogether. We show that a model-independent shift in alpha caused by electroweak penguin amplitudes in B --> pi pi and B --> rho rho, Δalpha_{EWP}=1.5+- 0.3 degree, may be slightly different in B --> rho pi. Other sources of isospin-breaking in these processes are briefly discussed.

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arXiv2004

On measuring alpha in B(t)-> rho^\pm pi^\mp

Defining a most economical parametrization of time-dependent B-> rho^\pm pi^\mp decays, including a measurable phase alpha_{eff} which equals the weak phase alpha in the limit of vanishing penguin amplitudes, we propose two ways for determining alpha in this processes. We explain the limitation of one method, assuming only that two relevant tree amplitudes factorize and that their relative strong phase, delta_t, is negligible. The other method, based on broken flavor SU(3), permits a determination of alpha in B^0-> rho^\pm pi^\mp in an overconstrained system using also rate measurements of B^{0,+}-> K^* pi and B^{0,+}->rho K. Current data are shown to restrict two ratios of penguin and tree amplitudes, r_\pm, to a narrow range around 0.2, and to imply an upper bound |alpha_{eff} - alpha| < 15 degrees. Assuming that delta_t is much smaller than 90 degrees, we find alpha =(93\pm 16) degrees and (102 \pm 20) degrees using BABAR and BELLE results for B(t)-> rho^\pm pi^mp. Avoiding this assumption for completeness, we demonstrate the reduction of discrete ambiguities in alpha with increased statistics, and show that SU(3) breaking effects are effectively second order in r_\pm.

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arXiv2004

Obtaining alpha from B-->rho+- pi-+

We discuss how to extract the weak phase alpha from present data on B--> rho+- pi-+ decays. Introducing alpha_{eff} and constraining the difference from alpha using flavor SU(3), one arrives at alpha=(95+- 16) degrees, if a testable assumption of a small relative strong phase between the two relevant tree amplitudes is employed to distinguish between discrete ambiguities. On the long run we advocate the combined fit to B--> rho+- pi-+ and SU(3) related modes. The effect of SU(3) breaking in this approach is expected to be small, because of relatively small penguin pollution.

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arXiv2004

Using untagged B^0 -> D K_S to determine gamma

It is shown that the weak phase gamma=arg(-V_{ud}V^*_{ub}V_{cb}V_{cd}^*) can be determined using only untagged decays B/Bbar--> D K_S. In order to reduce the uncertainty in gamma, we suggest combining information from B^{+-}--> DK^{+-} and from untagged B^0 decays, where the D meson is observed in common decay modes. Theoretical assumptions, which may further reduce the statistical error, are also discussed.

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