NEW OBSERVATION OF A PARITY VIOLATION IN CESIUM

Bouchiat, M.A. ; Guena, J. ; Pottier, L. ; et al.
Phys.Lett.B 134 (1984) 463-468, 1984.
Inspire Record 200186 DOI 10.17182/hepdata.30610

The parity violation induced by weak neutral currents is measured in a ΔF =1 hyperfine component of the 6S–7S transition of the Cs atom. The measured value ( Im E PV 1 β ) = −1.78 ± 0.26 (statistical rms deviation) ±0.12 (systematic uncertainty) mV/cm, agrees with our previous measurement in a ΔF =0 component, and constitutes an important cross-check. Our result excludes a parity violation induced by a purely axial hadronic neutral current.

1 data table

(7s)2S1/2:F=3 --> (6s)2S1/2:F=4 transition.


Observation of a Parity Violation in Cesium

Bouchiat, M.A. ; Guena, J. ; Hunter, L. ; et al.
Phys.Lett.B 117 (1982) 358, 1982.
Inspire Record 180105 DOI 10.17182/hepdata.30837

We have measured a parity violation in the 6S–7S transition of Cs in an electric field. Our result is Im E 1 pv β = -1.34 ± 0.22 ( rms statistical deviation ) ± ∼0.11 ( systematic uncertainty ) mV cm; E 1 pv is the parity violating electric dipole amplitude, ß is the vector polarizability. This result is consistent with the Weinberg-Salam prediction.

1 data table

(7s)2S1/2:F=4 --> (6s)2S1/2:F=4 transition.


ATOMIC PARITY VIOLATION MEASUREMENTS IN THE HIGHLY FORBIDDEN (6)S(1/2) - (7)S(1/2) CESIUM TRANSITION. 3. DATA ACQUISITION AND PROCESSING. RESULTS AND IMPLICATIONS

Bouchiat, M.A. ; Guena, J. ; Pottier, L. ; et al.
J.Phys.(France) 47 (1986) 1709-1730, 1986.
Inspire Record 232798 DOI 10.17182/hepdata.38588

This paper completes the detailed presentation of our PV experiment on the 6S1/2 - 7S1/2 transition in Cs. A detailed description of the data acquisition and processing is given. The results of two independent measurements made on ΔF = 0 and ΔF =1 hfs components agree, providing an important cross-check. After a complete reanalysis of systematics and calibration, the precision is slightly improved, leading to the weighted average Im Epv 1/β = - 1.52 ± 0.18 mV/cm. Later results from an independent group agree quite well. With the semi-empirical value β = (26.8 ± 0.8) a30, our result yields Epv1 = (- 0.79 ± 0.10) x 10-11 i |e|a0. Coupled with the atomic calculations, this implies that the weak nuclear charge of Cs is Qw = -68 ± 9. This value agrees with the standard electroweak theory and leads to a weak interaction angle sin2 θ W = 0.21 ± 0.04. The complementarity of these measurements with high energy experiments is illustrated.

3 data tables

Revision of the earlier experiment PL 117B, 358. (7s)2S1/2:F=4 --> (6s)2S1/2:F=4 transition.

Revision of the earlier experiment PL 134B, 463. (7s)2S1/2:F=3 --> (6s)2S1/2:F=4 transition.

Combined of the two above measurements following the philosophy: quadratic sum of the statistical and systematic uncertainties and weighting each result by the squared reciprocal of that uncertainty. (7s)2S1/2 --> (6s)2S1/2 transitions.


Search for nearly mass-degenerate higgsinos using low-momentum mildly-displaced tracks in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Aakvaag, Erlend ; Abbott, Braden Keim ; et al.
CERN-EP-2024-012, 2024.
Inspire Record 2751400 DOI 10.17182/hepdata.146944

Higgsinos with masses near the electroweak scale can solve the hierarchy problem and provide a dark matter candidate, while detecting them at the LHC remains challenging if their mass-splitting is $\mathcal{O}$(1 GeV). This Letter presents a novel search for nearly mass-degenerate higgsinos in events with an energetic jet, missing transverse momentum, and a low-momentum track with a significant transverse impact parameter using 140 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}$ = 13 TeV collected by the ATLAS experiment. For the first time since LEP, a range of mass-splittings between the lightest charged and neutral higgsinos from 0.3 GeV to 0.9 GeV is excluded at 95% confidence level, with a maximum reach of approximately 170 GeV in the higgsino mass.

31 data tables

Number of expected and observed data events in the SR (top), and the model-independent upper limits obtained from their consistency (bottom). The symbol $\tau_{\ell}$ ($\tau_{h}$) refers to fully-leptonic (hadron-involved) tau decays. The Others category includes contributions from minor background processes including $t\bar{t}$, single-top and diboson. The individual uncertainties can be correlated and do not necessarily sum up in quadrature to the total uncertainty. The bottom section shows the observed 95% CL upper limits on the visible cross-section ($\langle\epsilon\sigma\rangle_{\mathrm{obs}}^{95}$), on the number of generic signal events ($S_{\mathrm{obs}}^{95}$) as well as the expected limit ($S_{\mathrm{exp}}^{95}$) given the expected number (and $\pm 1\sigma$ deviations from the expectation) of background events.

Expected (dashed black line) and observed (solid red line) 95% CL exclusion limits on the higgsino simplified model being considered. These are shown with $\pm 1\sigma_{\mathrm{exp}}$ (yellow band) from experimental systematic and statistical uncertainties, and with $\pm 1\sigma_{\mathrm{theory}}^{\mathrm{SUSY}}$ (red dotted lines) from signal cross-section uncertainties, respectively. The limits set by the latest ATLAS searches using the soft lepton and disappearing track signatures are illustrated by the blue and green regions, respectively, while the limit imposed by the LEP experiments is shown in gray. The dot-dashed gray line indicates the predicted mass-splitting for the pure higgsino scenario.

Expected (dashed black line) and observed (solid red line) 95% CL exclusion limits on the higgsino simplified model being considered. These are shown with $\pm 1\sigma_{\mathrm{exp}}$ (yellow band) from experimental systematic and statistical uncertainties, and with $\pm 1\sigma_{\mathrm{theory}}^{\mathrm{SUSY}}$ (red dotted lines) from signal cross-section uncertainties, respectively. The limits set by the latest ATLAS searches using the soft lepton and disappearing track signatures are illustrated by the blue and green regions, respectively, while the limit imposed by the LEP experiments is shown in gray. The dot-dashed gray line indicates the predicted mass-splitting for the pure higgsino scenario.

More…

Searches for exclusive Higgs boson decays into $D^*\gamma$ and $Z$ boson decays into $D^0\gamma$ and $K^0_s\gamma$ in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Aakvaag, Erlend ; Abbott, Braden Keim ; et al.
CERN-EP-2024-037, 2024.
Inspire Record 2763131 DOI 10.17182/hepdata.147194

Searches for the exclusive decays of the Higgs boson into $D^*\gamma$ and of the $Z$ boson into $D^0\gamma$ and $K^0_s\gamma$ can probe flavour-violating Higgs and $Z$ boson couplings to light quarks. Searches for these decays are performed with a $pp$ collision data sample corresponding to an integrated luminosity of $136.3$ fb$^{-1}$ collected at $\sqrt{s}=13$ TeV between 2016-2018 with the ATLAS detector at the CERN Large Hadron Collider. In the $D^*\gamma$ and $D^0\gamma$ channels, the observed (expected) 95$\%$ confidence-level upper limits on the respective branching fractions are ${\cal B}(H\rightarrow D^*\gamma)< 1.0 (1.2)\times 10^{-3}$, ${\cal B}(Z\rightarrow D^0\gamma)< 4.0 (3.4)\times 10^{-6}$, while the corresponding results in the $K^0_s\gamma$ channel are ${\cal B}(Z\rightarrow K^0_s\gamma)< 3.1 (3.0)\times 10^{-6}$.

2 data tables

Numbers of observed and expected background events for the $m_{\mathcal{M}\gamma}$ ranges of interest. Each expected background and the corresponding uncertainty is obtained by integrating the total pdf after a background-only fit to the data, where the uncertainty does not take into account statistical fluctuations in each mass range. Expected Higgs and $Z$ boson signal contributions, with their corresponding total systematic uncertainty, are shown for reference branching fractions of $10^{-3}$ and $10^{-6}$, respectively. Entries are marked with a dash when there is no signal of that type in the specified range.

Observed and expected (with the corresponding $\pm1\sigma$ intervals) 95% CL upper limits on the branching fractions for $H\rightarrow D^*\gamma$, $Z\rightarrow D^0\gamma$ and $Z\rightarrow K^0_s\gamma$. Standard Model production of the Higgs boson is assumed. The corresponding upper limits on the production cross-section times branching fraction $\sigma\times\mathcal{B}$ are also shown.


Search for flavour-changing neutral-current couplings between the top quark and the Higgs boson in multi-lepton final states in 13 TeV $pp$ collisions with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Aakvaag, Erlend ; Abbott, Braden Keim ; et al.
CERN-EP-2024-070, 2024.
Inspire Record 2773613 DOI 10.17182/hepdata.150998

A search is presented for flavour-changing neutral-current interactions involving the top quark, the Higgs boson and an up-type quark ($q=u,c$) with the ATLAS detector at the Large Hadron Collider. The analysis considers leptonic decays of the top quark along with Higgs boson decays into two $W$ bosons, two $Z$ bosons or a $\tau^{+}\tau^{-}$ pair. It focuses on final states containing either two leptons (electrons or muons) of the same charge or three leptons. The considered processes are $t\bar{t}$ and $Ht$ production. For the $t\bar{t}$ production, one top quark decays via $t\to Hq$. The proton-proton collision data set analysed amounts to 140 fb$^{-1}$ at $\sqrt{s}=13$ TeV. No significant excess beyond Standard Model expectations is observed and upper limits are set on the $t\to Hq$ branching ratios at 95% confidence level, amounting to observed (expected) limits of $\mathcal{B}(t\to Hu)<2.8\,(3.0) \times 10^{-4}$ and $\mathcal{B}(t\to Hc)<3.3\,(3.8) \times 10^{-4}$. Combining this search with other searches for $tHq$ flavour-changing neutral-current interactions previously conducted by ATLAS, considering $H\to b\bar{b}$ and $H\to\gamma\gamma$ decays, as well as $H\to\tau^{+}\tau^{-}$ decays with one or two hadronically decaying $\tau$-leptons, yields observed (expected) upper limits on the branching ratios of $\mathcal{B}(t\to Hu)<2.6\,(1.8) \times 10^{-4}$ and $\mathcal{B}(t\to Hc)<3.4\,(2.3) \times 10^{-4}$.

53 data tables

Pre-fit background composition of the SR$2\ell$ Dec. The table shows the event yields as opposed to just the percentages of the relevant background processes.

Pre-fit background composition of the SR$2\ell$ Prod. The table shows the event yields as opposed to just the percentages of the relevant background processes.

Pre-fit background composition of the SR$3\ell$ Dec. The table shows the event yields as opposed to just the percentages of the relevant background processes.

More…

Measurement of the branching ratio for the process b --> tau- anti-nu/tau X.

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Åkesson, P.F. ; et al.
Phys.Lett.B 520 (2001) 1-10, 2001.
Inspire Record 561580 DOI 10.17182/hepdata.49743

The inclusive branching ratio for the process b -> tau nu X has been measured using hadronic Z decays collected by the OPAL experiment at LEP in the years 1992-2000. The result is: BR(b -> tau nu X) = (2.78 +/- 0.18 +/- 0.51)% This measurement is consistent with the Standard Model expectation and puts a constraint of tan(beta) / M(H+/-) < 0.53 GeV-1 at the 95% confidence level on Type II Two Higgs Doublet Models.

1 data table

TAN(BETA) is the two-Higgs-doublet model parameter, while M_H is the mass of charged Higgs.


The cosmic ray proton plus helium energy spectrum measured by the ARGO-YBJ experiment in the energy range 3-300 TeV

The ARGO-YBJ collaboration Bartoli, B. ; Bernardini, P. ; Bi, X. J. ; et al.
Phys.Rev.D 91 (2015) 112017, 2015.
Inspire Record 1355361 DOI 10.17182/hepdata.73337

The ARGO-YBJ experiment is a full-coverage air shower detector located at the Yangbajing Cosmic Ray Observatory (Tibet, People's Republic of China, 4300 m a.s.l.). The high altitude, combined with the full-coverage technique, allows the detection of extensive air showers in a wide energy range and offer the possibility of measuring the cosmic ray proton plus helium spectrum down to the TeV region, where direct balloon/space-borne measurements are available. The detector has been in stable data taking in its full configuration from November 2007 to February 2013. In this paper the measurement of the cosmic ray proton plus helium energy spectrum is presented in the region 3-300 TeV by analyzing the full collected data sample. The resulting spectral index is $\gamma = -2.64 \pm 0.01$. These results demonstrate the possibility of performing an accurate measurement of the spectrum of light elements with a ground based air shower detector.

2 data tables

Proton plus helium flux measured at $5.0 \times 10^4$ GeV.

Light component energy spectrum measured by the ARGO-YBJ experiment by using the full 2008-2012 data sample in each energy bin.


eta-meson production in proton-proton collisions at excess energies of 40 and 72 MeV

Petren, H. ; Bargholtz, Chr. ; Bashkanov, M. ; et al.
Phys.Rev.C 82 (2010) 055206, 2010.
Inspire Record 882234 DOI 10.17182/hepdata.60320

The production of η mesons in proton-proton collisions has been studied using the WASA detector at the CELSIUS storage ring at excess energies of Q=40 MeV and Q=72 MeV. The η was detected through its 2γ decay in a near-4π electromagnetic calorimeter, whereas the protons were measured by a combination of straw chambers and plastic scintillator planes in the forward hemisphere. About 6.9×104 and 9.3×104 events were found at Q=40 MeV and Q=72 MeV, respectively, with background contributions of less than 5%. A simple parametrization of the production cross section in terms of low partial waves was used to evaluate the acceptance corrections. Strong evidence was found for the influence of higher partial waves. The Dalitz plots show the presence of p waves in both the pp and the η{pp} systems and the angular distributions of the η in the center-of-mass frame suggest the influence of d-wave η mesons.

6 data tables

Differential cross section for pp -> pp eta at proton beam energies of 1360 and 1445 MeV (excess energies of of 40 and 72 MeV). The angle theta* is that between the eta momentum and that of the beam in the overall CM system. The error shown in the table is the combined statistical and systematic uncertainty, excluding the overall normalization error.

Differential cross section for pp -> pp eta at proton beam energies of 1360 and 1445 MeV (excess energies of of 40 and 72 MeV). The angle theta** is that between the pp relative momentum and that of the eta in the diproton rest frame. The error shown in the table is the combined statistical and systematic uncertainty, excluding the overall normalization error.

Differential cross section for pp -> pp eta at a proton beam energy of 1360 MeV (excess energy Q = 40 MeV) with respect to the square of the final pp invariant mass. Note the change in units with respect to the figure.

More…

Measurement of the forward charged particle pseudorapidity density in pp collisions at sqrt{s} = 7 TeV with the TOTEM experiment

The TOTEM collaboration Antchev, G ; Atanassov, I. ; Avati, V. ; et al.
EPL 98 (2012) 31002, 2012.
Inspire Record 1115294 DOI 10.17182/hepdata.59403

The TOTEM experiment has measured the charged particle pseudorapidity density dN_{ch}/deta in pp collisions at sqrt{s} = 7 TeV for 5.3<|eta|<6.4 in events with at least one charged particle with transverse momentum above 40 MeV/c in this pseudorapidity range. This extends the analogous measurement performed by the other LHC experiments to the previously unexplored forward eta region. The measurement refers to more than 99% of non-diffractive processes and to single and double diffractive processes with diffractive masses above ~3.4 GeV/c^2, corresponding to about 95% of the total inelastic cross-section. The dN_{ch}/deta has been found to decrease with |eta|, from 3.84 pm 0.01(stat) pm 0.37(syst) at |eta| = 5.375 to 2.38 pm 0.01(stat) pm 0.21(syst) at |eta| = 6.375. Several MC generators have been compared to data; none of them has been found to fully describe the measurement.

1 data table

Charged-particle multiplicities in proton-proton collisions at a centre-of mass energy of 7 TeV as a function of pseudorapidity for events with the number of charged particles >=1 having transverse momentum >40 MeV and 5.3< absolute(pseudorapidity) <6.5.