Search for new physics in the $\tau$ lepton plus missing transverse momentum final state in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Tumasyan, A. ; Adam, W. ; Andrejkovic, J.W. ; et al.
JHEP 09 (2023) 051, 2023.
Inspire Record 2626189 DOI 10.17182/hepdata.135472

A search for physics beyond the standard model (SM) in the final state with a hadronically decaying tau lepton and a neutrino is presented. This analysis is based on data recorded by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, corresponding to a total integrated luminosity of 138 fb$^{=1}$. The transverse mass spectrum is analyzed for the presence of new physics. No significant deviation from the SM prediction is observed. Limits are set on the production cross section of a W' boson decaying into a tau lepton and a neutrino. Lower limits are set on the mass of the sequential SM-like heavy charged vector boson and the mass of a quantum black hole. Upper limits are placed on the couplings of a new boson to the SM fermions. Constraints are put on a nonuniversal gauge interaction model and an effective field theory model. For the first time, upper limits on the cross section of $t$-channel leptoquark (LQ) exchange are presented. These limits are translated into exclusion limits on the LQ mass and on its coupling in the $t$-channel. The sensitivity of this analysis extends into the parameter space of LQ models that attempt to explain the anomalies observed in B meson decays. The limits presented for the various interpretations are the most stringent to date. Additionally, a model-independent limit is provided.

15 data tables

The transverse mass distribution of $ au$ leptons and missing transverse momentum observed in the Run-2 data (black dots with statistical uncertainty) as well as the expectation from SM processes (stacked histograms). Different signal hypotheses normalized to 10 fb$^{-1}$ are illustrated as dashed lines for exemplary SSM W$\prime$ boson, QBH and EFT signal hypotheses. The ratios of the background-subtracted data yields to the expected background yields are presented in the lower panel. The combined statistical and systematic uncertainties in the background are represented by the grey shaded band in the ratio panel.

Bayesian upper exclusion limits at 95% CL on the product of the cross section and branching fraction of a W$\prime$ boson decaying to a $\tau$ lepton and a neutrino in the SSM model. For this model, W$\prime$ boson masses of up to 4.8 TeV can be excluded. The limit is given by the intersection of the observed (solid) limit and the theoretical cross section (blue dotted curve). The 68 and 95% quantiles of the limits are represented by the green and yellow bands, respectively. The $\sigma \mathcal{B}$ for an SSM W' boson, along with its associated uncertainty, calculated at NNLO precision in QCD is shown.

Bayesian 95% CL model-independent upper limit on the product of signal cross sections and branching fraction for the $\tau+\nu$ decay for a back-to-back $\tau$ lepton plus $p_{T}^{miss}$ topology. To calculate this limit, all events for signal, background, and data are summed starting from a minimum $m_{T}$ threshold and then divided by the total number of events. No assumption on signal shape is included in this limit. The expected (dashed line) and observed (solid line) limits are shown as well as the 68% and 95% CL uncertainty bands (green and yellow, respectively).

More…

Multi-particle azimuthal correlations for extracting event-by-event elliptic and triangular flow in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

The PHENIX collaboration Adare, A. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev.C 99 (2019) 024903, 2019.
Inspire Record 1670164 DOI 10.17182/hepdata.150019

We present measurements of elliptic and triangular azimuthal anisotropy of charged particles detected at forward rapidity $1<|\eta|<3$ in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV, as a function of centrality. The multiparticle cumulant technique is used to obtain the elliptic flow coefficients $v_2\{2\}$, $v_2\{4\}$, $v_2\{6\}$, and $v_2\{8\}$, and triangular flow coefficients $v_3\{2\}$ and $v_3\{4\}$. Using the small-variance limit, we estimate the mean and variance of the event-by-event $v_2$ distribution from $v_2\{2\}$ and $v_2\{4\}$. In a complementary analysis, we also use a folding procedure to study the distributions of $v_2$ and $v_3$ directly, extracting both the mean and variance. Implications for initial geometrical fluctuations and their translation into the final state momentum distributions are discussed.

21 data tables

Centrality dependence of (a) $v_2${2} and (b) $v_2${4}. (a) The red points indicate no pseudorapidity gap whereas the magenta points indicate a pseudorapidity gap of |$\Delta\eta$| > 2.0. (b) The black points indicate $v_2${4} with no pseudorapidity gap, the blue points indicate a two-subevent method with |$\Delta\eta$| > 2.0 but where some short-range pairs are allowed, and the red points indicate a two-subevent method with |$\Delta\eta$| > 2.0 where no short-range pairs are allowed.

Centrality dependence of (a) $v_2${2} and (b) $v_2${4}. (a) The red points indicate no pseudorapidity gap whereas the magenta points indicate a pseudorapidity gap of |$\Delta\eta$| > 2.0. (b) The black points indicate $v_2${4} with no pseudorapidity gap, the blue points indicate a two-subevent method with |$\Delta\eta$| > 2.0 but where some short-range pairs are allowed, and the red points indicate a two-subevent method with |$\Delta\eta$| > 2.0 where no short-range pairs are allowed.

Centrality dependence of (a) $v_2${2} and (b) $v_2${4}. (a) The red points indicate no pseudorapidity gap whereas the magenta points indicate a pseudorapidity gap of |$\Delta\eta$| > 2.0. (b) The black points indicate $v_2${4} with no pseudorapidity gap, the blue points indicate a two-subevent method with |$\Delta\eta$| > 2.0 but where some short-range pairs are allowed, and the red points indicate a two-subevent method with |$\Delta\eta$| > 2.0 where no short-range pairs are allowed.

More…

Measurements of directed, elliptic, and triangular flow in Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

The PHENIX collaboration Adare, A. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev.C 94 (2016) 054910, 2016.
Inspire Record 1394897 DOI 10.17182/hepdata.146752

Measurements of anisotropic flow Fourier coefficients ($v_n$) for inclusive charged particles and identified hadrons $\pi^{\pm}$, $K^{\pm}$, $p$, and $\bar{p}$ produced at midrapidity in Cu+Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV are presented. The data were collected in 2012 by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). The particle azimuthal distributions with respect to different order symmetry planes $\Psi_n$, for $n$~=~1, 2, and 3 are studied as a function of transverse momentum $p_T$ over a broad range of collisions centralities. Mass ordering, as expected from hydrodynamic flow, is observed for all three harmonics. The charged-particle results are compared to hydrodynamical and transport model calculations. We also compare these Cu$+$Au results with those in Cu$+$Cu and Au$+$Au collisions at the same $\sqrt{s_{_{NN}}}$, and find that the $v_2$ and $v_3$, as a function of transverse momentum, follow a common scaling with $1/(\varepsilon_n N_{\rm part}^{1/3})$.

37 data tables

$v_1$ ($p_T$) for charged hadrons measured with respect to the Cu spectator neutrons at midrapidity in Cu + Au collisions at $\sqrt{S_{NN}}$ 200 GeV.

$v_2(p_T)$ for charged hadrons measured at midrapidity in Cu + Au collisions at $\sqrt{S_N{N}}$ = 200 GeV.

$v_3(p_T)$ for charged hadrons measured at midrapidity in Cu + Au collisions at $\sqrt{S_N{N}}$ = 200 GeV.

More…

Measurement of the relative yields of $\psi(2S)$ to $\psi(1S)$ mesons produced at forward and backward rapidity in $p$$+$$p$, $p$$+$Al, $p$$+$Au, and $^{3}$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

The PHENIX collaboration Adare, A. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev.C 95 (2017) 034904, 2017.
Inspire Record 1487575 DOI 10.17182/hepdata.149529

The PHENIX Collaboration has measured the ratio of the yields of $\psi(2S)$ to $\psi(1S)$ mesons produced in $p$$+$$p$, $p$$+$Al, $p$$+$Au, and $^{3}$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV over the forward and backward rapidity intervals $1.2<|y|<2.2$. We find that the ratio in $p$$+$$p$ collisions is consistent with measurements at other collision energies. In collisions with nuclei, we find that in the forward ($p$-going or $^{3}$He-going) direction, the relative yield of $\psi(2S)$ mesons to $\psi(1S)$ mesons is consistent with the value measured in \pp collisions. However, in the backward (nucleus-going) direction, the $\psi(2S)$ is preferentially suppressed by a factor of $\sim$2. This suppression is attributed in some models to breakup of the weakly-bound $\psi(2S)$ through final state interactions with comoving particles, which have a higher density in the nucleus-going direction. These breakup effects may compete with color screening in a deconfined quark-gluon plasma to produce sequential suppression of excited quarkonia states.

9 data tables

Summary of the measured ratios of $\Psi$(2S)/$\Psi$(1S) mesons.

Summary of the measured ratios of $\Psi$(2S)/$\Psi$(1S) mesons.

Summary of the measured ratios of $\Psi$(2S)/$\Psi$(1S) mesons.

More…

Measurement of higher cumulants of net-charge multiplicity distributions in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=7.7-200$ GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.C 93 (2016) 011901, 2016.
Inspire Record 1378005 DOI 10.17182/hepdata.146751

We report the measurement of cumulants ($C_n, n=1\ldots4$) of the net-charge distributions measured within pseudorapidity ($|\eta|<0.35$) in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=7.7-200$ GeV with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g. $C_1/C_2$, $C_3/C_1$) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in the ratios of the cumulants as a function of collision energy. The measured values of $C_1/C_2 = \mu/\sigma^2$ and $C_3/C_1 = S\sigma^3/\mu$ can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy.

10 data tables

Efficiency corrected cumulants of net-charge distributions as a function of $\langle N_{part} \rangle$ from Au+Au collisions at different collision energies.

Efficiency corrected cumulants of net-charge distributions as a function of $\langle N_{part} \rangle$ from Au+Au collisions at different collision energies.

Efficiency corrected cumulants of net-charge distributions as a function of $\langle N_{part} \rangle$ from Au+Au collisions at different collision energies.

More…

Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at $\sqrt{s}= 7$ and 8 TeV

The ATLAS & CMS collaborations Aad, G. ; Abbott, B. ; Abbott, D.C. ; et al.
JHEP 07 (2023) 213, 2023.
Inspire Record 2088291 DOI 10.17182/hepdata.110250

A combination of measurements of the inclusive top-quark pair production cross-section performed by ATLAS and CMS in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV at the LHC is presented. The cross-sections are obtained using top-quark pair decays with an opposite-charge electron-muon pair in the final state and with data corresponding to an integrated luminosity of about 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and about 20 fb$^{-1}$ at $\sqrt{s}=8$ TeV for each experiment. The combined cross-sections are determined to be $178.5 \pm 4.7$ pb at $\sqrt{s}=7$ TeV and $243.3^{+6.0}_{-5.9}$ pb at $\sqrt{s}=8$ TeV with a correlation of 0.41, using a reference top-quark mass value of 172.5 GeV. The ratio of the combined cross-sections is determined to be $R_{8/7}= 1.363\pm 0.032$. The combined measured cross-sections and their ratio agree well with theory calculations using several parton distribution function (PDF) sets. The values of the top-quark pole mass (with the strong coupling fixed at 0.118) and the strong coupling (with the top-quark pole mass fixed at 172.5 GeV) are extracted from the combined results by fitting a next-to-next-to-leading-order plus next-to-next-to-leading-log QCD prediction to the measurements. Using a version of the NNPDF3.1 PDF set containing no top-quark measurements, the results obtained are $m_t^\text{pole} = 173.4^{+1.8}_{-2.0}$ GeV and $\alpha_\text{s}(m_Z)= 0.1170^{+ 0.0021}_{-0.0018}$.

2 data tables

Full covariance matrix including all systematic uncertainties expressed as nuisance parameters. With the exception of the cross section parameters, all parameters were normalised to 1 before the fit. Therefore, the diagonal elements represent the constraint in quadrature.

Full covariance matrix including all systematic uncertainties expressed as nuisance parameters. With the exception of the cross section parameters, all parameters were normalised to 1 before the fit. Therefore, the diagonal elements represent the constraint in quadrature.


Trends in Yield and Azimuthal Shape Modification in Dihadron Correlations in Relativistic Heavy Ion Collisions

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.Lett. 104 (2010) 252301, 2010.
Inspire Record 845169 DOI 10.17182/hepdata.146557

Fast parton probes produced by hard scattering and embedded within collisions of large nuclei have shown that partons suffer large energy loss and that the produced medium may respond collectively to the lost energy. We present measurements of neutral pion trigger particles at transverse momenta p^t_T = 4-12 GeV/c and associated charged hadrons (p^a_T = 0.5-7 GeV/c) as a function of relative azimuthal angle Delta Phi at midrapidity in Au+Au and p+p collisions at sqrt(s_NN) = 200 GeV. These data lead to two major observations. First, the relative angular distribution of low momentum hadrons, whose shape modification has been interpreted as a medium response to parton energy loss, is found to be modified only for p^t_T &lt; 7 GeV/c. At higher p^t_T, the data are consistent with unmodified or very weakly modified shapes, even for the lowest measured p^a_T. This observation presents a quantitative challenge to medium response scenarios. Second, the associated yield of hadrons opposite to the trigger particle in Au+Au relative to that in p+p (I_AA) is found to be suppressed at large momentum (IAA ~ 0.35-0.5), but less than the single particle nuclear modification factor (R_AA ~0.2).

16 data tables

Average away-side $I^{head}_{AA}$ above 2 GeV/$c$ for various $\pi^0$ trigger momenta in central and midcentral collisions where $|\Delta\phi - \pi| < \pi/6$. Note: a 6% scale uncertainty applies to all $I_{AA}$ values.

Away-side jet widths from a Gaussian fit by $h^{\pm}$ partner momentum for various $\pi^0$ trigger momenta in $p+p$ collisions.

Away-side jet widths from a Gaussian fit by $h^{\pm}$ partner momentum for various $\pi^0$ trigger momenta in Au+Au collisions.

More…

Observation of the electromagnetic field effect via charge-dependent directed flow in heavy-ion collisions at the Relativistic Heavy Ion Collider

The STAR collaboration Abdulhamid, M.I. ; Aboona, B.E. ; Adam, J. ; et al.
Phys.Rev.X 14 (2024) 011028, 2024.
Inspire Record 2649979 DOI 10.17182/hepdata.139915

The deconfined quark-gluon plasma (QGP) created in relativistic heavy-ion collisions enables the exploration of the fundamental properties of matter under extreme conditions. Non-central collisions can produce strong magnetic fields on the order of $10^{18}$ Gauss, which offers a probe into the electrical conductivity of the QGP. In particular, quarks and anti-quarks carry opposite charges and receive contrary electromagnetic forces that alter their momenta. This phenomenon can be manifested in the collective motion of final-state particles, specifically in the rapidity-odd directed flow, denoted as $v_1(\mathsf{y})$. Here we present the charge-dependent measurements of $dv_1/d\mathsf{y}$ near midrapidities for $\pi^{\pm}$, $K^{\pm}$, and $p(\bar{p})$ in Au+Au and isobar ($_{44}^{96}$Ru+$_{44}^{96}$Ru and $_{40}^{96}$Zr+$_{40}^{96}$Zr) collisions at $\sqrt{s_{\rm NN}}=$ 200 GeV, and in Au+Au collisions at 27 GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider. The combined dependence of the $v_1$ signal on collision system, particle species, and collision centrality can be qualitatively and semi-quantitatively understood as several effects on constituent quarks. While the results in central events can be explained by the $u$ and $d$ quarks transported from initial-state nuclei, those in peripheral events reveal the impacts of the electromagnetic field on the QGP. Our data put valuable constraints on the electrical conductivity of the QGP in theoretical calculations.

9 data tables

Directed flow of $p$ and $\bar{p}$ vs rapidity in Au+Au 200 GeV 50-80% centrality.

Directed flow of $p$ and $\bar{p}$ vs rapidity in Zr+Zr and Ru+Ru 200 GeV (combined) 50-80% centrality.

Directed flow of $p$ and $\bar{p}$ vs rapidity in Au+Au 27 GeV 50-80% centrality.

More…

First Constraints on WIMP-Nucleon Effective Field Theory Couplings in an Extended Energy Region From LUX-ZEPLIN

The LZ collaboration Aalbers, J. ; Akerib, D.S. ; Musalhi, A.K. Al ; et al.
2023.
Inspire Record 2729878 DOI 10.17182/hepdata.145873

Following the first science results of the LUX-ZEPLIN (LZ) experiment, a dual-phase xenon time projection chamber operating from the Sanford Underground Research Facility in Lead, South Dakota, USA, we report the initial limits on a model-independent non-relativistic effective field theory describing the complete set of possible interactions of a weakly interacting massive particle (WIMP) with a nucleon. These results utilize the same 5.5 t fiducial mass and 60 live days of exposure collected for the LZ spin-independent and spin-dependent analyses while extending the upper limit of the energy region of interest by a factor of 7.5 to 270 keVnr. No significant excess in this high energy region is observed. Using a profile-likelihood ratio analysis, we report 90% confidence level exclusion limits on the coupling of each individual non-relativistic WIMP-nucleon operator for both elastic and inelastic interactions in the isoscalar and isovector bases.

58 data tables

Data points used in analysis in log_10(S2)-S1 space.

Data selection efficiency as a function of nuclear recoil energy

Isoscalar WIMP-nucleon elastic coupling limit for Operator 8

More…

Cold Nuclear Matter Effects on J/psi Yields as a Function of Rapidity and Nuclear Geometry in Deuteron-Gold Collisions at sqrt(s_NN) = 200 GeV

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, C. ; et al.
Phys.Rev.Lett. 107 (2011) 142301, 2011.
Inspire Record 871818 DOI 10.17182/hepdata.146014

We present measurements of J/psi yields in d+Au collisions at sqrt(s_NN) = 200 GeV recorded by the PHENIX experiment and compare with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/psi rapidity (-2.2 < y < 2.4) with high statistical precision and are compared with two theoretical models: one with nuclear shadowing combined with final state breakup and one with coherent gluon saturation effects. To remove model dependent systematic uncertainties we also compare the data to a simple geometric model. We find that calculations where the nuclear modification is linear or exponential in the density weighted longitudinal thickness are difficult to reconcile with the forward rapidity data.

10 data tables

$J/\psi$ $B_{ll}$ $dN/dy$ in $p+p$ collisions as a function of rapidity. (All uncertainties are absolute. The sys. A uncertainty includes both the statistical uncertainty and the point-to-point uncorrelated systematic, sys. B represents uncertainties that are correlated from point to point, and sys. C represents uncertainties in the overall normalization.)

$J/\psi$ $B_{ll}$ $dN/dy$ in $d$+Au collisions as a function of rapidity. The $d$+Au yields are divided by the average number of nucleon-nucleon collisions $\langle N_{coll}$(0-100%)$\rangle$ = 7.6. (All uncertainties are absolute. The sys. A uncertainty includes both the statistical uncertainty and the point-to-point uncorrelated systematic, sys. B represents uncertainties that are correlated from point to point, and sys. C represents uncertainties in the overall normalization.)

Mid rapidity $d$+Au —> $e^+e^-$ $J/\psi$ invariant yields at $\sqrt{s}$=200 GeV. (All uncertainties are absolute. The sys. A uncertainty includes both the statistical uncertainty and the point-to-point uncorrelated systematic, sys. B represents uncertainties that are correlated from point to point, and sys. C represents uncertainties in the overall normalization.)

More…