We report the observation of the decay $B^{-} \rightarrow D^{(*)+}_{s} K^{-} \ell^{-} \barν_{\ell}$ based on $342 \mathrm {\,fb}^{-1}}$ of data collected at the $\Y4S$ resonance with the BABAR detector at the PEP-II $e^{+}e^{-}$ storage rings at SLAC. A simultaneous fit to three $D^{+}_{s}$ decay chains is performed to extract the signal yield from measurements of the squared missing mass in the B meson decay. We observe the decay $B^{-} \rightarrow D^{(*)+}_{s} K^{-} \ell^{-} \barν_{\ell}$ with a significance greater than five standard deviations (including systematic uncertainties) and measure its branching fraction to be $\BR(B^{-} \rightarrow D^{(*)+}_{s} K^{-} \ell^{-} \barν_{\ell}) = [6.13^{+1.04}_{-1.03}(\mathrm{stat.})\pm0.43(\mathrm{syst.}) \pm 0.51(\BR(D_{s}))]\times10^{-4}$, where the last error reflects the limited knowledge of the $D_{s}$ branching fractions.
The latest results on the direct experimental search for a Standard Model Higgs boson decaying to a pair of Z bosons are presented. Three distinct final states are considered: $H\rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$, $H\rightarrow ZZ\rightarrow \ell\ellνν$, and $H\rightarrow ZZ\rightarrow \ell\ell qq$, where $\ell = e, μ$. A dataset of more than 1fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 7$ TeV collected by the ATLAS detector at the CERN LHC during the on-going 2011 run is used. In this model and for these final states, Higgs boson masses in the ranges 192 GeV $< m_H < $…
Searches for $B$ mesons decaying to final states containing a baryon and a lepton are performed, where the baryon is either $Λ_c$ or $Λ$ and the lepton is a muon or an electron. These decays violate both baryon and lepton number and would be a signature of physics beyond the standard model. No significant signal is observed in any of the decay modes, and upper limits in the range $(3.2-520) \times 10^{-8}$ are set on the branching fractions at the 90% confidence level.
This work presents the search for the semileptonic baryonic B decay $B^- \rightarrow Λ_c^+ \bar{p} \ell^- \barν_{\ell}$. The used data comprises the complete BABAR data set of $470 \cdot 10^{6}$ $B\bar{B}$ events, collected at the SLAC National Accelerator Laboratory. Using a pole-model decay simulation, we obtain upper limits with $90\%$ confidence level of $B(B^- \rightarrow Λ_c^+ \bar{p} e^- \barν_{e})\cdot \frac{B(Λ_c^+ \rightarrow p K^- π^+)}{5\%} < 1.2 \times 10^{-4}$, $B(B^- \rightarrow Λ_c^+ \bar{p} μ^- \barν_μ)\cdot \frac{B(Λ_c^+ \rightarrow p K^- π^+)}{5\%} < 2.5 \times 10^{-4}$, $B(…
We present a measurement of the effective weak mixing angle parameter $\sin^2θ_\text{eff}^{\ell}$, in $p\bar{p}\rightarrow Z/γ^* \rightarrow μ^+μ^-$ events at a center of mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider and corresponding to 8.6 fb$^{-1}$ of integrated luminosity. The measured value of $\sin^2θ_\text{eff}^{\ell}[μμ]=0.23016 \pm 0.00064$ is further combined with the result from the D0 measurement in $p\bar{p}\rightarrow Z/γ^{*}\rightarrow e^{+} e^{-}$ events, resulting in $\sin^2θ_\text{eff}^{\ell} [\text{comb.}]=0.23095 \pm 0.00040$. This …
A measurement of the Higgs boson production cross sections via associated $WH$ and $ZH$ production using $H \rightarrow WW^{\ast} \rightarrow \ellν\ellν$ decays, where $\ell$ stands for either an electron or a muon, is presented. Results for combined $WH$ and $ZH$ production are also presented. The analysis uses events produced in proton-proton collisions collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The data correspond to an integrated luminosity of 36.1 fb$ ^{-1}$ recorded at a centre-of-mass energy of 13 TeV. The products of the $H \rightarrow WW^{\ast}$ b…
The mass of the Higgs boson is measured in the $H\rightarrow ZZ^* \rightarrow 4\ell$ and in the $H\rightarrow γγ$ decay channels with 36.1 fb$^{-1}$ of proton-proton collision data from the Large Hadron Collider at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector in 2015 and 2016. The measured value in the $H\rightarrow ZZ^* \rightarrow 4\ell$ channel is $m_{H}^{ZZ^{*}} = 124.79 \pm 0.37$ GeV, while the measured value in the $H\rightarrow γγ$ channel is $m_{H}^{γγ} = 124.93 \pm 0.40$ GeV. Combining these results with the ATLAS measurement based on 7 TeV and 8 TeV proton-proton …
The absolute branching fractions for the decays $D^-_s\!\rightarrow\!\ell^-\barν_{\ell}$ ($\ell=e$, $μ$, or $τ$) are measured using a data sample corresponding to an integrated luminosity of 521 fb$^{-1}$ collected at center of mass energies near 10.58 GeV with the \mbox{\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the PEP-II $e^+e^-$ collider at SLAC. The number of $D^-_s$ mesons is determined by reconstructing the recoiling system $DKXγ$ in events of the type $e^+e^-{\rightarrow}DKXD^{*-}_s$, where $D^{*-}_s\rightarrow D^-_sγ$ and $X$ repres…
After Run 1 of the LHC, global fits to $b \rightarrow s \ell \ell$ observables show a deviation from the Standard Model (SM) with a significance of $\sim$ 4 standard devations. An example of a $b \rightarrow s \ell \ell$ process is the decay of a $B_{s}^0$ meson into two muons ($B_{s}^0 \rightarrow μ^+ μ^-$). The latest analysis of $B_{(s)}^0 \rightarrow μ^+ μ^-$ decays by LHCb with Run 1 and Run 2 data is presented. The $B_{s}^0 \rightarrow μ^+ μ^-$ decay is observed for the first time by a single experiment. In addition, the first measurement of the $B_{s}^0 \rightarrow μ^+ μ^-$ effective li…
An improved measurement of the mass of the Higgs boson is derived from a combined fit to the invariant mass spectra of the decay channels $H\rightarrow γγ$ and $H \rightarrow ZZ^{*} \rightarrow 4\ell$. The analysis uses the $pp$ collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at center-of-mass energies of 7 TeV and 8 TeV, corresponding to an integrated luminosity of 25 fb$^{-1}$. The measured value of the Higgs boson mass is $m_H$ = 125.36 $\pm$ 0.37 (stat) $\pm$ 0.18 (syst) GeV. This result is based on improved energy-scale calibrations for photons, el…
Results of the measurements of the 125 GeV Higgs boson properties with proton-proton collision data at $\sqrt{s}=13$ TeV collected by CMS detector are presented. The used Higgs boson decay channels include the five major decay modes, $\mathrm{H}\rightarrowγγ$, $\mathrm{H}\rightarrow{\rm Z}{\rm Z}\rightarrow4\ell$, $\mathrm{H}\rightarrow{\rm W}{\rm W}\rightarrow\ellν\ellν$, $\mathrm{H}\rightarrowτ^{+}τ^{-}$ and $\mathrm{H}\rightarrow b\bar{b}$, and two rare decay modes, $\mathrm{H}\rightarrowμ^{+}μ^{-}$ and $\mathrm{H}\rightarrow{\rm Z}/γ^{*}+γ\rightarrow\ell\ellγ$, with $\ell={\rm e},μ$. The m…
Measurements of $ZZ \rightarrow \ell\ellνν$ and $ZZjj \rightarrow \ell\ellννjj$ productions in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
Searches for the rare hadronic decays $B^0 \rightarrow p\bar{p}p\bar{p}$ and $B^0_{s} \rightarrow p\bar{p}p\bar{p}$ are performed using proton-proton collision data recorded by the LHCb experiment and corresponding to an integrated luminosity of 9$\rm{fb}^{-1}$. Significances of $9.3\,σ$ and $4.0\,σ$, including statistical and systematic uncertainties, are obtained for the $B^0 \rightarrow p\bar{p}p\bar{p}$ and $B^0_{s} \rightarrow p\bar{p}p\bar{p}$ signals, respectively. The branching fractions are measured relative to the topologically similar normalisation decays $B^0 \rightarrow J/ψ(\right…
We report the results of a study of the exclusive charmless semileptonic decays, $B^{+} \rightarrow η^{(\prime)} \ell^{+} ν$ and $B^{0} \rightarrow π^{-} \ell^{+} ν$, undertaken with approximately 464 million $\ensuremath{B\kern 0.18em\bar{\kern -0.18em B}}$ pairs collected at the $Υ(4S)$ resonance with the ${{\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}}}$ detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions for $B^{+} \rightarrow η\ell^{+} ν…
Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3 fb$^{-1}$ of $pp$ collisions produced by the Large Hadron Collider at a center-of-mass energy of $\sqrt{s} = 8$ TeV and recorded by the ATLAS detector. Cross sections are obtained from measured $H \rightarrow γγ$ and $H \rightarrow ZZ ^{*}\rightarrow 4\ell$ event yields, which are combined accounting for detector efficiencies, fiducial acceptances and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, num…
We study the processes $p\bar{p} \rightarrow WZ \rightarrow \ellν\ell^+\ell-$ and $p\bar{p} \rightarrow ZZ \rightarrow \ell^+\ell^-ν\barν, where $\ell$ = $e$ or $μ$. Using 8.6 fb$^{-1} of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron collider, we measure the $WZ$ production cross section to be 4.50$^{+0.63}_{-0.66} pb which is consistent with, but slightly above a prediction of the standard model. The ZZ cross section is measured to be 1.64 $\pm$ 0.46 pb, in agreement with a prediction of the standard model. Combination with an earlier analysis of the $ZZ \right…
We present a new measurement of the $WZ\rightarrow \ellν\ell\ell$ ($\ell = e,μ$) cross section and limits on anomalous triple gauge couplings. Using 4.1 fb$^{-1}$ of integrated luminosity of $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV, we observe 34 $WZ$ candidate events with an estimated background of $6.0 \pm 0.4$ events. We measure the $WZ$ production cross section to be $3.90^{+1.06}_{-0.90}$ pb, in good agreement with the standard model prediction. We find no evidence for anomalous $WWZ$ couplings and set 95% C.L. limits on the coupling parameters, $-0.075 < λ_{Z} < 0.093$ and $-0.027 …
The properties of the Higgs boson measured in bosonic decay channels ($H \rightarrow γγ$, $H \rightarrow ZZ^* \rightarrow 4\ell$, $H \rightarrow WW^{*} \rightarrow \ellν\ellν$, $H \rightarrow Zγ$) with 25 fb$^{-1}$ of pp collision data from the Large Hadron Collider run-1 collected by the ATLAS experiment are presented. The results include an improved measurement of the mass of the Higgs boson from a combined fit to the invariant mass spectra of the decay channels $H \rightarrow γγ$ and $H \rightarrow ZZ^* \rightarrow 4\ell$, which yields $m_H = 125.36 \pm 0.37$ (stat) $\pm 0.18$ (syst) GeV = …
Measurements of Higgs boson production via gluon-gluon fusion and vector-boson fusion using $H\rightarrow WW^\ast \rightarrow \ellν\ellν$ decays in $pp$ collisions with the ATLAS detector and their effective field theory interpretations
A combined measurement of differential and inclusive total cross sections of Higgs boson production is performed using 36.1 fb$^{-1}$ of 13 TeV proton-proton collision data produced by the LHC and recorded by the ATLAS detector in 2015 and 2016. Cross sections are obtained from measured $H \rightarrow γγ$ and $H \rightarrow ZZ^* \rightarrow 4\ell$ event yields, which are combined taking into account detector efficiencies, resolution, acceptances and branching fractions. The total Higgs boson production cross section is measured to be 57.0$^{+6.0}_{-5.9}$ (stat.) $^{+4.0}_{-3.3}$ (syst.) pb, in…
The semi-leptonic baryonic $b\to s$ decay, $Λ_b\rightarrow Λ\ell^+\ell^-$, has been studied and new angular observables and asymmetries have been proposed which can test the presence of new physics beyond the standard model.
Recent results on inclusive charmless semileptonic decays of B mesons are reviewed. Emphasis is given to measurements on the recoil of fully reconstructed B mesons, which allow to exploit several regions of phase space. Preliminary averages of the CKM matrix element $|V_{ub}|$ from the Heavy Flavour Working Group are shown, using four different theoretical calculations.
Inclusive and differential fiducial cross sections of Higgs boson production in proton-proton collisions are measured in the $H \rightarrow ZZ^* \rightarrow 4\ell$ decay channel. The proton-proton collision data were produced at the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector in 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb$^{-1}$. The inclusive fiducial cross section in the $H \rightarrow ZZ^* \rightarrow 4\ell$ decay channel is measured to be 3.62 $\pm$ 0.50 (stat) $^{+0.25}_{-0.20}$ (sys) fb, in agreement with the Stand…
An angular analysis of the decay ${\overline{B} \rightarrow D^\ast \ell^- \overlineν_\ell}$, $\ell\in\{e,μ\}$, is reported using the full $e^+e^-$ collision data set collected by the \babar experiment at the $Υ(4S)$ resonance. One $B$ meson from the ${Υ(4S)\to B\overline{B}}$ decay is fully reconstructed in a hadronic decay mode, which constrains the kinematics and provides a determination of the neutrino momentum vector. The kinematics of the semileptonic decay is described by the di-lepton mass squared, $q^2$, and three angles. The first unbinned fit to the full four-dimensional decay rate i…
The decays $\bar{B} \rightarrow D^{(*)} τ^- \barν_τ$ are good probes to new physics beyond the Standard Model. The ratios of branching fractions $R(D^{(*)}) \equiv \mathit{BF}(\bar{B} \rightarrow D^{(*)} τ^- \barν_τ) / \mathit{BF}(\bar{B} \rightarrow D^{(*)} \ell^- \barν_\ell)$ (where $\ell^- = e^-, μ^-$) measured by Belle, BaBar and LHCb show 3.9$σ$ deviation from the SM expectations as of 2015. In 2016, the Belle collaboration has shown two new measurements for the $\bar{B} \rightarrow D^{(*)} τ^- \barν_τ$ decay. These include the first application of the semileptonic tagging to the $R(D^*)$…
We measure the ratio of cross sections, $σ(p\bar{p}\rightarrow Z+2~b~\text{jets})$/$σ(p\bar{p}\rightarrow Z+\text{2 jets})$, for associated production of a $Z$ boson with at least two jets with transverse momentum $p_T^{\rm jet} > 20$ GeV and pseudorapidity $|η^{\rm jet}| < 2.5$. This measurement uses data corresponding to an integrated luminosity of 9.7 fb$^{-1}$ collected by the \DO experiment in Run II of Fermilab's Tevatron \ppbar Collider at a center-of-mass energy of 1.96 TeV. The measured integrated ratio of $0.0236\pm0.0032\left(\mbox{stat}\right)\pm0.0035\left(\mbox{syst}\right)$ is i…
Semileptonic $b \rightarrow s\ell \ell$ processes constitute a good probe for new physics phenomena: new particles contributing to the loops could affect branching fractions and angular distributions, and have different couplings to different lepton families, thus violating lepton flavour universality. Recent results from the LHCb experiment are reviewed.
$K \rightarrow π\ell^+ \ell^-$ decays, $\ell = e, μ$, will be one of the goals of future kaon facilities, like NA62 (CERN) and K$^0$TO (J-PARC). We review briefly the theoretical status of those processes.
Using a data sample of $(448.1\pm2.9)\times 10^6~ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, we present measurements of branching fractions for the decays $χ_{cJ} \rightarrow Σ^+ \barΣ^-$ and $Σ^0 \barΣ^0$. The decays $χ_{c1,2}\rightarrow Σ^+ \barΣ^-$ and $Σ^0 \barΣ^0$ are observed for the first time, and the branching fractions for $χ_{c0}\rightarrow Σ^+ \barΣ^-$ and $Σ^0 \barΣ^0$ decays are measured with improved precision. The branching fraction ratios between the charged and neutral modes are consistent with the prediction of isospin symmetry.
The production of a prompt photon in association with a $Z$ boson is studied in proton-proton collisions at a centre-of-mass energy $\sqrt{s} =$ 13 TeV. The analysis uses a data sample with an integrated luminosity of 139 fb$^{-1}$ collected by the ATLAS detector at the LHC from 2015 to 2018. The production cross-section for the process $pp \rightarrow \ell^+\ell^-γ+X$ ($\ell = e, μ$) is measured within a fiducial phase-space region defined by kinematic requirements on the photon and the leptons, and by isolation requirements on the photon. An experimental precision of 2.9% is achieved for the…
This Letter reports a measurement of the exclusive $γγ\rightarrow \ell^+\ell^- (\ell=e, μ)$ cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV by the ATLAS experiment at the LHC, based on an integrated luminosity of $4.6$ fb$^{-1}$. For the electron or muon pairs satisfying exclusive selection criteria, a fit to the dilepton acoplanarity distribution is used to extract the fiducial cross-sections. The cross-section in the electron channel is determined to be $σ_{γγ\rightarrow e^+e^-}^{\mathrm{excl.}} = 0.428 \pm 0.035 (\mathrm{stat.}) \pm 0.018 (\mathrm{syst.})$ pb f…
Based on 106 million $ψ(3686)$ events collected with the BESIII detector at the BEPCII, the decay $ψ(3686) \rightarrow ωK \bar{K} π$ is studied. Enhancements around 1.44 GeV/$c^{2}$ and the $f_{1}(1285)$ are observed in the mass spectrum of $K \bar{K}π$, and the corresponding branching fractions are measured, as well as the branching fractions of $ψ(3686) \rightarrow ωK^{*+}K^{-}+c.c.$ and $ψ(3686) \rightarrow ω\bar{K}^{*0}K^{0}+c.c.$, all for the first time.
We present a measurement of the electron charge asymmetry in $p\bar{p}\rightarrow W+X \rightarrow eν+X$ events at a center-of-mass energy of 1.96 TeV, using data corresponding to 9.7~fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The asymmetry is measured as a function of the electron pseudorapidity and is presented in five kinematic bins based on the electron transverse energy and the missing transverse energy in the event. The measured asymmetry is compared with next-to-leading-order predictions in perturbative quantum chromodynamics and …
Dalitz decay of $K^*(892) \rightarrow K \ell^+\ell^-$: A New Probe for Hadronic Structure and Dark Photon Searches
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Henan University of Animal Husbandry and Economy（河南牧业经济学院）；Center for High Energy Physics, Henan Academy of Sciences（河南省科学院高能物理中心）；Nanjing Normal Univerisity（南京师范大学）
The $b \rightarrow s γ$, $b \rightarrow d γ$ and $b \rightarrow s \ell^+ \ell^-$ processes are allowed at higher order via the electroweak loop or box diagrams in the Standard model. It is sensitive probe to search for new physics beyond the Standard model because new particles might enter in the loop. We present preliminary results of branching fraction of the $\bar{B} \rightarrow X_s γ$, $CP$ asymmetry in the $\bar{B} \rightarrow X_{s+d} γ$, and the forward-backward asymmetry in the $\bar{B} \rightarrow X_s \ell^+ \ell^-$. The results are based on a data sample containing $772 \times 10^6 B\…
This paper presents the potential measurement at 1.4 TeV CLIC of the cross-section (times branching ratio) of the Higgs production via $WW$ fusion with the Higgs subsequently decaying in $ZZ^\ast$, ${σ(Hν_e\bar{ν_e})\times BR(H\rightarrow ZZ^\ast)}$, and of the Higgs production via $ZZ$ fusion with the Higgs subsequently decaying in $b\bar{b}$, ${σ(He{^+}e{^-})\times BR(H\rightarrow b\bar{b})}$. For the $H\rightarrow ZZ^\ast$ decay the hadronic final state, ${ZZ^\ast\rightarrow q\bar{q}q\bar{q}}$, and the semi-leptonic final state, ${ZZ^\ast\rightarrow q\bar{q}l^+l^-}$, are considered. The res…
In this Analysis we investigated the possibility of the measurement of Higgs self-coupling at ILC through the process $e^++e^-\rightarrow ZHH$ using fast simulation data. So far two combinations of decay modes: $Z\rightarrow q \bar q,H\rightarrow b\bar b, H\rightarrow WW^*$ and $Z\rightarrow l \bar l, H\rightarrow b\bar b, H\rightarrow b\bar b$ were studied. Our preliminary results show that it is very challenging to suppress the huge standard model backgrounds effectively.
The ratio of the cross section for $p\bar{p}$ interactions producing a $Z$ boson and at least one $b$ quark jet to the inclusive $Z+{\rm jet}$ cross section is measured using $4.2\ {\rm fb}^{-1}$ of $p\bar{p}$ collisions collected with the \dzero\ detector at the Fermilab Tevatron collider at $\sqrt{s}=1.96$ TeV. The $Z\rightarrow\ell^+\ell^-$ candidate events with at least one $b$ jet are discriminated from $Z+$ charm and light jet(s) events by a novel technique that exploits the properties of the tracks associated to the jet. The measured ratio is $0.0193\pm0.0027$ for events having a jet wi…
A search for a heavy neutral Higgs boson, $A$, decaying into a $Z$ boson and another heavy Higgs boson, $H$, is performed using a data sample corresponding to an integrated luminosity of 139 fb$^{-1}$ from proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded by the ATLAS detector at the LHC. The search considers the $Z$ boson decaying into electrons or muons and the $H$ boson into a pair of $b$-quarks or $W$ bosons. The mass range considered is 230-800 GeV for the $A$ boson and 130-700 GeV for the $H$ boson. The data are in good agreement with the background predicted by the Standard Model…
A search is presented for a high-mass Higgs boson in the $H\rightarrow\ell\ell\ell\ell$, $H\rightarrow\ell\ellνν$, $H\rightarrow\ell\ell qq$, and $H\rightarrowννqq$ decay modes using the ATLAS detector at the CERN Large Hadron Collider. The search uses proton-proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb$^{-1}$. The results of the search are interpreted in the scenario of a heavy Higgs boson with a width that is small compared with the experimental mass resolution. The Higgs boson mass range considered extends up to 1 TeV for all…
We report a measurement of the branching fractions for $B^{0} \rightarrow π^- \ell^+ν$ and $B^{0} \rightarrow ρ^-\ell^+ν$ decays, using charged and neutral $B$ decays with isospin constraints. We find ${\cal B}(B^{0} \rightarrow π^- \ell^+ν} = (1.41 \pm 0.05 \pm 0.07) \times 10^{-4}$, and ${\cal B}(B^{0} \rightarrow ρ^-\ell^+ν} = (1.75 \pm 0.15 \pm 0.27) \times 10^{-4}$, where the first error is statistical and the second is systematic. We measure $Δ{\cal B}/Δq^2$, with 6 $q^2$ bins for $B^{0} \rightarrow π^- \ell^+ν$ and 3 \q2 bins for $B^{0} \rightarrow ρ^-\ell^+ν$, and compare the distribut…
We present a measurement of the $W$ boson production charge asymmetry in $p\bar{p}\rightarrow W+X \rightarrow eν+X$ events at a center of mass energy of 1.96 TeV, using 9.7 fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The neutrino longitudinal momentum is determined using a neutrino weighting method, and the asymmetry is measured as a function of the $W$ boson rapidity. The measurement extends over wider electron pseudorapidity region than previous results, and is the most precise to date, allowing for precise determination of proton part…
Evidence is presented for the baryonic $B$ meson decay $\bar{B}\rightarrow D^0 Λ\barΛ$ based on a data sample of $471 \times 10^6$ $B\bar{B}$ pairs collected with the {\it BABAR} detector at the PEP2 asymmetric $e^+e^-$ collider located at the SLAC National Accelerator Laboratory. The branching fraction is determined to be $\mathcal{B}(\bar{B}\rightarrow D^0 Λ\barΛ) = (9.8^{+2.9}_{-2.6} \pm 1.9)\times 10^{-6}$, corresponding to a significance of $3.4$ standard deviations including systematic uncertainties. A search for the related baryonic $B$ meson decay $\bar{B}\rightarrow D^0 Σ^0 \barΛ$ wit…
Composite effective field theory signal from anomalous quartic gauge couplings for $ZZ(\rightarrow\ell\ellνν)jj$ and $Zγ(\rightarrowννγ)jj$ productions
Measurement of the total and differential Higgs boson production cross-sections at $\sqrt{s} = 13$ TeV with the ATLAS detector by combining the $H \rightarrow ZZ^* \rightarrow 4\ell$ and $H \rightarrow γγ$ decay channels
We present a measurement of the fundamental parameter of the standard model, the weak mixing angle, in $p\bar{p}\rightarrow Z/γ^{*}\rightarrow e^{+}e^{-}$ events at a center of mass energy of 1.96 TeV, using data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected by the D0 detector at the Fermilab Tevatron. The effective weak mixing angle is extracted from the forward-backward charge asymmetry as a function of the invariant mass around the Z boson pole. The measured value of $\sin^2θ_{\text{eff}}^{\text{$\ell$}}=0.23147 \pm 0.00047$ is the most precise measurement from light qua…
The study of flavour-changing neutral currents (FCNC) gives access to important tests of the Standard Model (SM) and allows to search for hints of beyond the SM phenomena. We present here the study of the very rare decays $B^0\rightarrow μ^+μ^-$ and $B_s^0\rightarrow μ^+μ^-$ using data corresponding to an integrated luminosity of 25 fb$^{-1}$ of $7$~TeV and $8$~TeV proton-proton collisions collected with the ATLAS detector during the LHC Run 1. For $B^0$, an upper limit on the branching fraction is set at BR$(B^0 \rightarrow μ^+μ^-) < 4.2\times 10^{-10}$ at 95\% confidence level. For $B^0_s$, …
The NA62 experiment at the CERN SPS reports the first search for $K^+ \rightarrow π^+ ν\barν$ using the decay-in-flight technique, based on a sample of $1.21\times10^{11}$ $K^+$ decays collected in 2016. The single event sensitivity is $3.15\times 10^{-10}$, corresponding to 0.267 Standard Model events. One signal candidate is observed while the expected background is 0.152 events. This leads to an upper limit of $14 \times 10^{-10}$ on the $K^+ \rightarrow π^+ ν\barν$ branching ratio at 95\% CL.
A search is presented for the four-body decay $B^0\rightarrow p p \bar{p} \bar{p}$ in a sample of $471$ million $B\bar{B}$ pairs collected with the BaBar detector, operated at the SLAC PEP-II asymmetric-energy $e^+e^-$ collider. The center-of-mass energy is $10.58$ GeV. From a fit to the distribution of the energy-substituted mass $m_{\mathrm{ES}}$, the result $\mathcal{B}(B^0\rightarrow p p \bar{p} \bar{p})=(1.1 \pm 0.5 \pm 0.2) \times 10^{-7}$ is extracted, where the first uncertainty is statistical and the second is systematic. The significance of the signal is $2.9$ standard deviations. Th…
The semitauonic decay $\bar{B} \rightarrow D^* τ^- \barν_τ$ is sensitive to new physics beyond the Standard Model (SM) that has an enhanced coupling to the $τ$ lepton. In the ratio of branching fractions $R(D^*) = \mathcal{B}(\bar{B} \rightarrow D^* τ^- \barν_τ) / \mathcal{B}(\bar{B} \rightarrow D^* \ell^- \barν_\ell)$, where $\ell^- = e^-$ or $μ^-$, a 3.3$σ$ anomaly was observed. In order to investigate the anomaly further, Belle performed a new $R(D^*)$ measurement using one-prong hadronic $τ$ decays, which was statistically independent of the previous two measurements. This measurement incl…
Several recent searches for exotic and rare decays of the Standard Model Higgs boson with the ATLAS and CMS detectors are presented. The searches are performed on $\sqrt{s}$=13 TeV proton-proton collisions data collected at the LHC between 2015 and 2018. The topics covered include searches for the Higgs boson decays into two pseudoscalars, $H\rightarrow aa$, in three different final states, $2b2μ$, $4b$ and $2\mu2τ$, search for lepton-flavour violating Higgs decays, $H\rightarrow μτ/ eτ$, and search for a rare $H\rightarrow \ell\ell γ$ decay. ATLAS presents evidence for the $H\rightarrow \ell\…
Decays $K^{+} \rightarrow μ^{+}ν_μ ν\bar ν$ and $K^{+}\rightarrow e^{+}ν_{e} ν\bar ν$ are examined to the leading order in momenta in the framework of Chiral Perturbation Theory. Predictions of the Standard Model for the muon and electron differential energy spectra and branching ratios of $K_{μ3 ν}$ and $K_{e 3 ν}$ are presented.
We compute the contribution of the decays $K_L \rightarrow π^0 Q \bar Q$ and $K^+ \rightarrow π^+ Q \bar Q$, where $Q$ is a dark fermion of the dark sector, to the measured widths for the rare decays $K^+\rightarrow π^+ ν\bar ν$ and $K_L\rightarrow π^0 ν\bar ν$. The recent experimental limit for $Γ(K^+ \rightarrow π^+ ν\bar ν)$ from NA62 sets a new and very strict bound on the dark-sector parameters. A branching ratio for $K_L \rightarrow π^0 Q \bar Q$ within the reach of the KOTO sensitivity is possible. The Grossman-Nir bound is weakened by the asymmetric effect of the different kinematic cu…
ATLAS exclusion and discovery potentials of Standard Model Higgs boson searches at the LHC at 14 TeV, 10 TeV and 7 TeV center-of-mass energy are reviewed. For a LHC center-of-mass energy of 7 TeV and integrated luminosity of 1 fb$^{-1}$, contributions from the important decay channels $\Hboson \rightarrow \Wboson\Wboson^{(*)} \rightarrow \ellν\ellν$, $\Hboson \rightarrow \Zboson\Zboson^{(*)} \rightarrow \ell\ell\ell\ell$ and $\Hboson \rightarrow γγ$ are considered, based on recent full Monte Carlo simulations at 14 and 10 TeV and the cross-section rescaling for the 7 TeV center-of-mass energy.…
The tree-level $b\rightarrow c{\ell}\barν_{\ell}$ based hadronic transitions have been on the focus of much attention since recording significant deviations of the experimental data, on the ratios of the branching fractions in $ τ$ and $ e-μ$ channels of the semileptonic $ B \rightarrow D $ transition, from the SM predictions by BaBar Collaboration in 2012. It can be of great importance to look whether similar discrepancies take place in the semileptonic baryonic $Λ_{b}\rightarrow Λ_{c}{\ell}\barν_{\ell}$ decay channel or not. In this accordance we estimate the decay width as well as the ratio…
We give detailed results of $\mathcal{O}(α)$ QED corrections (both real emission and virtual corrections) to $B\to K\ell^+\ell^-$ modes. Requiring the real emission to be gauge invariant, the structure of the contact term(s) is fixed. The calculation is done with a fictitious photon mass as the IR regulator and results are shown to be independent of it, establishing cancellation of the soft divergences. Results are presented for a choice of photon energy, $k_{max}$, and photon angle $θ_{cut}$. The QED effects are negative, thereby reducing the rate compared to that without QED effects. Electro…
We perform a helicity amplitude analysis for the processes of $e^+e^-$$\rightarrow$$J/ψ,ψ(2S)\rightarrowΞ(1530)\barΞ(1530)\rightarrowππΞ\barΞ\rightarrowΛ\bar\Lambda4π\rightarrow p\bar{p}6π$. The joint angular distribution for these processes are obtained, which allows a proper estimation of the detection efficiency using helicity amplitude information. In addition, the sensitivities of measurement of hyperon asymmetry decay parameters for these processes are discussed.
