This version is published in Chinese Physics Letters 42, 010201 (2025), which is updated from the White Paper on STCF charm physics contributing to the Snowmass 2021. 14 pages, 5 table
The high-luminosity Super $τ$-Charm Factory (STCF) will be a crucial facility for charm-physics research, particularly for the precise measurement of electroweak parameters, measuring $D^0$-$\bar{D}^0$ mixing parameters, investigating Charge-Parity (CP) violation within the charm sector, searching for the rare and forbidden decays of charmed hadrons, and addressing other foundational questions related to charmed hadrons. With the world's largest charm-threshold data, the STCF aims to achieve high sensitivity in studying the strong phase of neutral $D$ mesons using quantum correlation, complementing studies at LHCb and Belle II, and contributing to the understanding of CP violations globally. The STCF will also enable world-leading precision in measuring the leptonic decays of charmed mesons and baryons, providing constraints on the Cabibbo-Kobayashi-Maskawa matrix and strong-force dynamics. Additionally, the STCF will explore charmed hadron spectroscopy. The advanced detector and clean experimental environment of the STCF will enable unprecedented precision, help address key challenges in the Standard Model, and facilitate the search for potential new physics.
Tests of discrete symmetry violation have played an important role in understand the structure of weak interactions in the Standard Model of particle physics. Historically these measurements have been extensively performed at experiments with large samples of K and B mesons. A high luminosity tau-charm facility presents physicists with the opportunity to comprehensively explore discrete symmetry violation and test the Standard Model using tau leptons, charm mesons and charmed baryons. This paper discusses several possible measurements for a future tau-charm factory.
Several authors have proposed methods to measure the phase $γ$ of the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle using decays of the type $B\to DK$. We show how to remove uncertainties from these measurements and increase their sensitivity by measuring CP-conserving phases at a charm factory.
We propose a set of measurements at a charm factory to determine the $D^0-\bar D^0$ mixing parameters $ΔM$ and $ΔΓ$ and the strong phase difference $δ$ between doubly-Cabibbo-suppressed (DCS) and Cabibbo-favored (CF) neutral $D$ decays into $K^-π^+$. The method can also be used to measure strong phase differences between other corresponding DCS and CF amplitudes. These phase differences are important for studies of $D^0$--$\bar D^0$ mixing.
Inspired by the recent discovery of the $X(6900)$ meson at {\tt LHCb} experiment, we investigate the inclusive production rate of the $C$-odd fully-charmed tetraquarks associated with light hadrons at the $B$ factory within the nonrelativistic QCD (NRQCD) factorization framework. The short-distance coefficient is computed at lowest order in velocity and $α_s$. Employing the diquark-antidiquark model to roughly estimate the long-distance NRQCD matrix elements, we predict the rate for inclusive production of the $1^{+-}$ $T_{4c}$ state and discuss the observation prospects at {\tt Belle 2} exper…
The charm physics program accessible to a Tau-Charm Factory is summarized. Semileptonic, leptonic, hadronic, rare and forbidden charm decay modes are discussed, as well as \dmix\ mixing and CP violation in the charm sector. The theoretical expectations in the Standard Model and beyond as well as the experimental capabilities of a Tau-Charm Factory are examined for each of the above processes. {To appear in {\it The Tau-Charm Factory in the Era of B-Factories and CESR}, Stanford, CA, August 15-16, 1994}
In this paper we study the impact of data that can be obtained from a Charm Factory on the determination of the CKM parameter gamma from decays of the form B -> D0 K where the D0 decays to specific inclusive and exclusive final states. In particular, for each exclusive final state $f$, the charm factory can determine the strong phase difference between D0-> f and D0-bar -> f by exploiting correlations in psi(3770)-> D0 D0-bar. This provides crucial input to the determination of gamma via the interference of B+- -> K+- D0 -> f with B+- -> K+- D0-bar -> f. We discuss how the method may be genera…
I discuss the special opportunities that a Tau-Charm Factory offers for identifying gluonic excitations, hybrid charmonium and other exotic hadronic states. (Invited talk at TCF Workshop, Marbella, 1-6June)
This talk summarizes the status of the charmonium system, with particular emphasis on outstanding problems in QCD spectroscopy which a tau-charm factory can address.
Main parameters of the linac-ring type charm-tau factory are discussed. Different sets of parameters for an electron linac and a positron ring have been considered. It is shown that L=10^33 cm-2 s-1 and even more can be achieved. The physics goals of this machine in investigation for charmed particles and tau lepton properties are briefly discussed. Advantages of the proposed machine in comparison with standard (ring-ring) type charm-tau factory proposals will be the possibility of the search for rare decays of tau lepton and charm quark and study of D^0-D^-0 oscillations.
The Tau-Charm Factory combines the optimum conditions to perform a high-precision investigation of the $τ$ and $ν_τ$ leptons, the $c$ quark, and light-quark, glueball and hybrid spectroscopy. An overview of the broad physics program that this facility will address is presented.
The prospects for tau physics at future high-luminosity facilities are briefly discussed. Although important (and often complementary) contributions will be made from other machines, the unique experimental environment near threshold makes the Tau-Charm Factory the best experimental tool for $τ$ physics.
The cross-section for the double charmed baryon production at a $B$-factory is estimated on the basis of the perturbative QCD calculations for the $c c$-diquark production as well as of the quark-hadron duality.
Open charm hadrons are excellent probe to study the dynamics of quarks and gluons inside hadrons. Because the mass of a charm quark is heavier than $Λ_{QCD}$, the so called heavy quark symmetry emerges in the hadron containing a charm quark and plays a central role in the classification and constraining the interactions. Belle and BaBar, which are B-factory experiments, have made significant advances in the field of open charm hadron spectroscopy in these 15 years. In this article, experimental advances on both open charm mesons and baryons by B-factory experiments are reviewed. Finally, the p…
I review the sensitivities achieved by and projected for fixed-target charm experiments in CP violation, flavor-changing neutral-current and lepton-number-violating decays, and mixing, and I describe the Charm2000 experiment intended to run at Fermilab in the Year ~2000. If approved, Charm2000 will in many of these areas exceed the sensitivities projected for a Tau/Charm Factory, but the Tau/Charm Factory retains certain qualitative advantages.
We calculate the time-dependent and time-integrated decay rates of $(D^0\bar{D}^0)\rightarrow (K^{\pm}π^{\mp})(l^{\pm}X^{\mp})$ at the $ψ(3.77)$ and $ψ(4.14)$ resonances. The possibilities to distinguish between the effects of $D^0-\bar{D}^0$ mixing and doubly Cabibbo suppressed decay (DCSD) are illustrated, and the signal of $CP$ violation induced by the interplay of mixing and DCSD is discussed. Ratios of the decay rates of $(D^0\bar{D}^0)\rightarrow (K^{\pm}π^{\mp})(K^{\pm}π^{\mp})$ to that of $(D^0\bar{D}^0)\rightarrow (K^+π^-)(K^-π^+)$ are also recalculated by accommodating $CP$ violation…
We apply the newly developed NRQCD factorization formula to analyze the exclusive production of the fully-charmed tetraquark $T_{4c}$ plus a hard photon at $B$ factory. For simplicity, in this work we have concentrated on the associated production of the $0^{++}$ and $2^{++}$ tetraquarks with a photon. With some rough estimates about the size of the unknown nonperturbative NRQCD matrix elements, we predict the production rates of these types of exclusive channels at $\sqrt{s}=10.6$ GeV and also assess their observation prospect at {\tt Belle 2} experiment.
We systematically investigate the possibility of finding CP/T violation in the $τ$ sector at Tau-Charm Factory. CP/T violation may occur at $τ$ pair production process, expressed as electric dipole moment, and at $tau$ decay processes. By assuming that electric dipole moment as large as $10^{-19}$e-cm and CP/T violation effect orignating from $τ$ decay as large as $10^{-3}$ are observable at Tau-Charm Factory, we studied all the possible extensions of the SM which are relevent for generating CP/T violation in $τ$ sector. And we pointed there are a few kind of models, which are hopeful for gene…
The present data imply that $ϕ(2170)$ may not be an excited state of $ϕ$, but is a four quark state with $ss\bar s \bar s$ constituents. Furthermore, there are no two mesons of $s\bar s$ available to form a molecule which fits the mass spectrum of $ϕ(2170)$, thus we suggest it should be an $ss\bar s \bar s$ tetraquark state. In this scenario, we estimate its decay rates through the fall-apart mechanism. Our theoretical estimates indicate that its main decay modes should be $ϕ(2170)$ into $ϕf_0(980)$, $ h_1η$, $ h_1η'$, $K_1(1270)K$ and $K_1(1400)K$. Under this hypothesis the modes $ϕ(2170)\to …
In a recent paper, eight semileptonic parameters were defined to specify the most general Lorentz-invariant spin correlation functions for tau semileptonic decays. The parameters were physically defined in terms of tau-decay partial-width intensities for polarized final states. This paper studies how these parameters can be simply measured at a tau/charm factory with longitudinally polarized beams without using spin-correlation techniques. Thereby the parameters can also be used to bound the effective-mass scales $ Λ$ for ``new physics" such as arising from lepton compositeness, leptonic CP vi…
A method for measuring the average longitudinal polarization of the electron beam at an electron-positron collider operating near the $J/ψ$ resonance is proposed. The method utilizes the differential cross-section of $J/ψ\to [Λ\to pπ^-][\barΛ\to\bar{p}π^+]$ decay. It can be used to measure the average longitudinal polarization of electrons with the statistical precision better than $10^{-3}$ at a Super Charm-Tau factory operating at the luminosity of $10^{35}~\mathrm{cm}{}^{-2}\mathrm{s}{}^{-1}$. The method is discussed in the context of the weak mixing angle measurement in the same experiment…
It is commonly believed that the LHVTs can be tested through measuring the Bell's inequalities. This scheme, for the massive particle system, was originally set up for the entangled K^0\bar{K^0} pair system from the ϕfactory. In this Letter we show that the J/Ψ-> K^0\bar{K^0} process is even more realistic for this goal. We analyze the unique properties of J/Ψin the detection of basic quantum effects, and find that it is possible to use J/Ψdecay as a test of LHVTs in the future τ-Charm factory. Our analyses and conclusions are generally also true for other heavy Onium decays.
The doubly charmed hadron production at B factories is of special importance for the study of the hadron structure and the color connections before hadronization. To suppress the combination background fluctuations of the reconstructed hadron mass spectra, we suggest a three-jet event shape trigger. After these three jets are identified by their energy and angular distributions, it is found that: 1) The background process $e^+ e^- \to c\bar {c} \to h's$ in consideration of the final hadron system $Λ_c^+K^-π^+ +X$ are significantly suppressed. 2) For the selected events, about half of the parti…
We investigate the possibility of searching the lepton-flavor-violating (LFV) $τ\rightarrow μγ$ rare decay at the Super Charm-Tau Factory (CTF). By comparing the kinematic distributions of the LFV signal and the standard model (SM) background, we develop an optimized event selection criteria which can significantly reduce the background events. It is concluded that new $2 σ$ upper limit of about $1.9 \times 10^{-9}$ on $Br(τ\rightarrow μγ)$ can be obtained at the CTF, which is beyond the capability of Super-B factory in searching $τ$ lepton rare decay. Within the framework of the scalar leptoq…
In our previous work [2], it has been found that sizable charmonium events via the channel $e^+e^- \to γ^*/Z^0 \to H(|c\bar{c}\rangle) +γ$ can be produced at the suggested super $Z$ factory, where $H(|c\bar{c}\rangle)$ represents the dominant color-singlet $S$-wave and $P$-wave charmonium states $J/ψ$, $η_c$, $h_c$ and $χ_{cJ}$ ($J=0, 1, 2$), respectively. As an important step forward, in the present paper, we present a next-to-leading order (NLO) QCD analysis within the framework of nonrelativistic QCD. In different to the case of $B$ factory in which the single charmonium production is domin…
In contrast with $B^0-\bar B^0$, $B_s-\bar B_s$ mixing where the standard model (SM) contributions overwhelm that of new physics beyond standard model (BSM), a measured relatively large $D^0-\bar D^0$ mixing where the SM contribution is negligible, definitely implies the existence of new physics BSM. It is natural to consider that the rare decays of D meson might be more sensitive to new physics, and the rare decay $D^0\to μ^+μ^-$ could be an ideal area to search for new physics because it is a flavor changing process. In this work we look for a trace of new physics BSM in the leptonic decays …
We assume that the two hidden charm pentaquark discovered at $LHCb$ are built by the three light quarks and the $c \bar{c}$ pair, both colour octets. in relative P-wave for the $\frac{5}{2}^+$ state and by the eigenvectors of the chromomagnetic interaction for the five constituents in S-wave for the four $\frac{3}{2}^-$ state with masses $4360$, $4410$, $4490$ and $4560$ MeV . The "open channel" $p $ $J/ψ$ has large components along the two first states and so appear as the $4380$ resonance and the $Λ_c$ $ \bar{D}^{0*}$ and $Σ_c$ $\bar{D}^*$ are "open channels" for the lower and higher resonan…
The recent measurements on $R_K$ and $R_π$ imply that there exists a possible violation of the leptonic flavor universality which is one of the cornerstones of the standard model. It is suggested that a mixing between sterile and active neutrinos might induce such a violation. In this work we consider the scenarios with one or two sterile neutrinos to explicitly realize the data while the constraints from the available experiments have been taken into account. Moreover, as indicated in literature, the deviation of the real PMNS matrix from the symmetric patterns may be due to a $μ-τ$ asymmetry…
We make a comparative and comprehensive study on the charmonium exclusive productions at the $e^+e^-$ collider with the collision energy either round the $Z^0$-boson mass for a super $Z$ factory or equals to 10.6 GeV for the $B$ factories as Belle and BABAR. We study the total cross sections for the charmonium production via the exclusive processes $e^+e^- \to γ^*/Z^0 \to H_{1}+H_{2}$ and $e^+e^- \to γ^*/Z^0 \to H_{1} +γ$, where $H_{1}$ and $H_{2}$ represent the dominant color-singlet $S$-wave and $P$-wave charmonium states respectively. Total cross sections versus the $e^+e^-$ collision energ…
Within the nonrelativistic quantum chromodynamics framework, we make a comprehensive study on the exclusive production of excited charmonium and bottomonium in $e^+e^-\to γ^*/Z^0 \to|(Q\bar{Q})[n]\rangle +γ$ ($Q=c$ or $b$ quarks) at future $Z$ factory, where the $[n]$ represents the color-singlet $n^1S_0,~n^3S_1,~n^1P_0$ and $n^3P_J$ ($n=1,2,3,4; J=0,1,2$) Fock states. The "improved trace technology" is adopted to derive the analytic expressions at the amplitude level, which is useful for calculating the complicated $nP$-wave channels. Total cross sections, differential distributions, and unce…
The potential of a Super Flavor Factory (SFF) for searches of New Physics is reviewed. While very high luminosity B physics is assumed to be at the core of the program, its scope for extensive charm and tau studies are also emphasized. The possibility to run at the Upsilon(5S) is also very briefly discussed; in principle, this could provide very clean measurements of B_s decays. The strength and reach of a SFF is most notably due to the possibility of examining an impressive array of very clean observables. The angles and the sides of the unitarity triangle can be determined with unprecedented…
The charm quark offers interesting opportunities to cross-check the mechanism of CP violation precisely tested in the strange and beauty sectors. In this paper, we exploit the angular and quantum correlations in the D\bar{D} pairs produced through the decay of the psi(3770) resonance in a charm factory to investigate CP-violation in two different ways. We build CP-violating observables in psi(3770) -> D\bar{D} -> (V_1V_2)(V_3 V_4) to isolate specific New Physics effects in the charm sector. We also consider the case of psi(3770) -> D\bar{D} -> (V_1V_2)(Kπ) decays, which provide a new way to me…
The Circular Electron Positron Collider (CEPC) is a large international scientific facility proposed by the Chinese particle physics community to explore the Higgs boson and provide critical tests of the underlying fundamental physics principles of the Standard Model that might reveal new physics. The CEPC, to be hosted in China in a circular underground tunnel of approximately 100 km in circumference, is designed to operate as a Higgs factory producing electron-positron collisions with a center-of-mass energy of 240 GeV. The collider will also operate at around 91.2 GeV, as a Z factory, and a…
We exploit the angular and quantum correlations in the $D\bar{D}$ pairs produced through the decay of the $ψ(3770)$ resonance in a charm factory to investigate CP-violation in two different ways. We consider the case of $ψ(3770)\rightarrow D\bar{D}\rightarrow (V_1V_2)(Kπ)$ decays, which provide a new way to measure the strong phase difference $δ$ between Cabibbo-favored and doubly-Cabibbo suppressed $D$ decays required in the determination of the CKM angle $γ$. We also build CP-violating observables in $ψ(3770)\rightarrow D\bar{D}\rightarrow (V_1V_2)(V_3 V_4)$ to isolate specific new physics e…
We describe a method for measuring CP-violation parameters from which the Cabibbo-Kobayashi-Maskawa angle $γ$ may be extracted. The method makes use of the total decay rates in $B^\pm \to DK^\pm$ decays, where the neutral $D$ meson decays to multibody final states. We analyze the error of the method using experimental CP-violation analysis variables that enable straightforward sensitivity comparison with other methods for extracting $γ$, and discuss the use of $B$-factory and charm-factory data to obtain the relevant charm decay information needed for this measurement. Measurement sensitivitie…
Within the color singlet model, we calculate the exclusive production of double charmonia, double bottomonia, and double $B_c$ mesons at future super $Z$ factory. The two heavy quarkonia or $B_c$'s are either two S-wave Fock states ($^1S_0, ~^3S_1$), or one S-wave and one P-wave states ($^1P_1,~^3P_J~(J=0,1,2)$). The top three $Z^0$ propagated channels in cross sections for double charmonia are $J/ψ+h_c,η_c+χ_{c2}$, and $η_c+χ_{c0}$. For double bottomonia, they are $η_b+Υ, Υ+χ_{b2}$, and $Υ+Υ$. For double $B_c$ mesons, they are $B_c^{*+}+B_c^{*-}$,$B_c^{*+}+χ_{bc2}^-$, and $η_{bc}^++B_c^{*-}$.…
A systematic theoretical evaluation of the cross section for hadron production in electron-positron collisions in the energy range just below the $B$ meson threshold is presented which includes charm and bottom mass effects and is accurate to order $\as^3$. The corresponding measurement in the energy region several $GeV$ above the threshold is also discussed.
We summarize the physics case of a high-luminosity e+e- flavour factory collecting an integrated luminosity of 50-75 ab^(-1). Many New Physics sensitive measurements involving B and D mesons and tau leptons, unique to a Super Flavour Factory, can be performed with excellent sensitivity to new particles with masses up to ~100 (or even ~1000 TeV). Flavour- and CP-violating couplings of new particles that may be discovered at the LHC can be measured in most scenarios, even in unfavourable cases assuming minimal flavour violation. Together with the LHC, a Super Flavour Factory, following either th…
We discuss how to extract non-Standard Model effects from B-factory phenomenology. We then analyze the prospects for uncovering evidence for Effective Supersymmetry, a class of supersymmetric models which naturally suppress flavor changing neutral currents and electric dipole moments without squark universality or small CP violating phases, in experiments at BaBar, BELLE, HERA-B, CDF/D0 and LHC-B.
In tau physics, we are at the frontier between the completion of the LEP program and the start of analyses from b-factories, which are expected to produce results in the coming years. Nice results from CLEO are steadily delivered in the meantime. For charm, impressive progress have been achieved by fixed target experiments in the search for CP violation and D^0 - \bar D^0 oscillations. First results from b-factories demonstrate the power of these facilities in such areas. The novel measurement of the D* width by CLEO happens to be rather different from current expectations. The absence of a ch…
In light of the results from the B factories, which clearly show that the Cabibbo-Kobayashi-Maskawa mechanism is the dominant source of the observed CP violation in K and B physics, only small deviations due to sources of CP violation beyond the Standard Model are likely. Therefore, in the quest for New Physics, null tests of the Standard Model become increasingly important. Motivated by these considerations, we describe a number of approximate null tests of the Standard Model. These tests provide several theoretically clean approaches to searching for new physics in the B system. We find that…
Second-generation theoretical technologies -- heavy quark expansions, QCD sum rules and QCD simulations on the lattice -- are arriving on the scene, allowing a treatment of charm decays that is genuinely based on QCD. The availability of those theoretical tools strengthens the case for the need for comprehensive precision measurements of charm decays. It is pointed out that the decays of charm mesons as well as of charm baryons have to be systematically analysed to gain control over theoretical uncertainties. A $τ$-charm factory with $E_{c.m.}\leq 5.5$ GeV is optimally suited for such a progra…
We calculate the next-to-leading order (NLO) radiative correction to the color-octet $h_c$ inclusive production in $e^+e^-$ annihilation at Super $B$ factory, within the nonrelativistic QCD factorization framework. The analytic expression for the NLO short-distance coefficient (SDC) accompanying the color-octet production operator $\mathcal{O}_8^{h_c}(^1S_0)$ is obtained after summing both virtual and real corrections. The size of NLO correction for the color-octet production channel is found to be positive and substantial. The NLO prediction to the $h_c$ energy spectrum is plagued with unphys…
Within the nonrelativistic QCD (NRQCD) factorization framework, we investigate the inclusive production of the $h_c$ meson associated with either light hadrons or charmed hadrons at $B$ factory energy $\sqrt{s}=10.58$ GeV. Both the leading color-singlet and color-octet channels are included. For the $h_c$ production associated with light hadrons, the total production rate is dominated by the color-octet channel, thus the future measurement of this process may impose useful constraint on the value of the color-octet matrix element $<{\cal O}^{h_c}_8({}^1S_0)>$; for the $h_c$ production associat…
Detailed studies of weak charm decays fill an important {\em future} role in high energy physics. Chief among them are: (i) validating the theoretical control achieved over hadronization as a worthwhile goal in its own right; (ii) calibrating our tools to saturate the discovery potential for New Physics in B decays; (iii) searching for New Physics in charm decays through hypothesis-generating research. The most promising area for the last item is a comprehensive study of \cp violation. Since we need a new \cp paradigm to implement baryogenesis, this is not an idle goal. Charm decays provide op…
We discuss potential to measure squark flavor mixings based on future data at super B factory and LHC. In particular we focus on the imaginary part of the mixings by investigating the CP violating observables. As a result, we find they are determined with the uncertainty about 10 % at best.
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 5 x 10^35 cm^-2s^-1, which is around 40 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. The sensitivity studies are a part of the activities associated with the preparation of a Letter of Intent for SuperK…
I share some personal reflections about the physics potential and the physics case that can be made for an e^+ e^- high-luminosity B-meson factory, as presented in my summary talk at the recent "Super B-Factory Workshop" jointly organized by the BaBar and Belle Collaborations (Honolulu, Hawaii, January 2004). These brief remarks will appear as part of a forthcoming, comprehensive report on the physics potential of such a ``10^{36} machine''.
A list is given of those open questions concerning the dynamics of charm decays where there exists a strong need for an answer. Such a need is based on lessons to be learnt about QCD -- either in their own right or for a better understanding of $B$ physics -- or on searches for New Physics with a small background from the Standard Model. The major items on this list are: lifetimes of the $Ξ_c^{0,+}$ baryons; semileptonic branching ratios of $D_s$, $Λ_c$ and $Ξ_c$ hadrons and absolute branching ratios for those states; radiative decays $D\rightarrow γK^*,\, γρ/ω, \, D_s \rightarrow γϕ/ω,\, D\ri…
Several scenarios beyond the minimal extension of the Standard Model still allow light non-standard Higgs bosons evading LEP bounds. We examine the mixing between a light CP-odd Higgs boson and $η_b$ states and its implications on a slight (but observable) lepton universality breaking in Upsilon decays which could be measured at the percent level at a (Super) B factory.
Following a brief review of our contributions to the 2006 European PP Strategy, recent comments on several topics are presented. First of all, it is emphasized that only the simplest version of the fourth chiral generation, namely, minimal SM4 (mSM4) with only one Higgs doublet is in some tension with the recent LHC data on the Higgs boson search. This tension, which follows from the relative strengths of the H --> 4l and Higgs --> γγ channels, can be naturally resolved if there is a mechanism to enhance the H-->γγ width (although any charged and heavy particle could enhance the H-γ-γ loop, 2H…
We summarize what has been learned about the neutrino mass spectrum and neutrino mixing, identify interesting open questions that can be answered by accelerator neutrino facilities of the future, and discuss the importance and physics of answering them.
A light non-standard Higgs boson decaying mainly into $τ^+τ^-$ has not been yet ruled out by LEP searches in several scenarios. We verify that, in the context of the Next-to-Minimal-Supersymmetric Standard Model, a low-mass CP-odd (mostly but not completely singlet-like) Higgs boson can couple strongly enough to down-type fermions to be detected in radiative $Υ$ decays into tauonic pairs at a high-luminosity B factory. Possible spectroscopic effects of a mixing with $η_b$ resonances are also analyzed
We present a quantitative appraisal of the physics potential for neutrino experiments at the front-end of a muon storage ring. We estimate the forseeable accuracy in the determination of several interesting observables, and explore the consequences of these measurements. We discuss the extraction of individual quark and antiquark densities from polarized and unpolarized deep-inelastic scattering. In particular we study the implications for the undertanding of the nucleon spin structure. We assess the determination of alpha_s from scaling violation of structure functions, and from sum rules, an…
The conclusions of the Physics Working Group of the international scoping study of a future Neutrino Factory and super-beam facility (the ISS) are presented. The ISS was carried by the international community between NuFact05, (the 7th International Workshop on Neutrino Factories and Superbeams, Laboratori Nazionali di Frascati, Rome, June 21-26, 2005) and NuFact06 (Ivine, California, 24{30 August 2006). The physics case for an extensive experimental programme to understand the properties of the neutrino is presented and the role of high-precision measurements of neutrino oscillations within t…
The recent successes of the SM do not weaken the arguments in favour of New Physics residing at the TeV scale. Finding and identifying it represents the prime challenge for a generation of high energy physicists. To differentiate between different scenarios of New Physics we need to analyze their impact on flavour dynamics. A continuing comprehensive program of heavy flavour studies instrumentalizing the high sensitivity of \cp analyses is intrinsically connected to LHC's core mission. In B decays we can typically expect no more than moderate deviations from SM predictions. $B_s$ transitions p…
