Fri·Jul 24, 2020Friday·July 24, 2020

1. 01*

   On the precise measurement of the $X(3872)$ mass and its counting rate

   Pablo G. Ortega🇪🇸 · Enrique Ruiz Arriola🇪🇸

   The lineshapes of specific production experiments of the exotic state such as $X(3872)$ with $J^{PC}=1^{++}$ quantum numbers involving triangle singularities have been found to become highly sensitive to the binding energy of weakly bound states, thus offering in principle the opportunity of benchmark determinations. We critically analyze recent proposals to extract accurately and precisely the $X(3872)$ mass, which overlook an important physical effect by regarding their corresponding production lineshapes as a sharp mass distribution and, thus, neglecting the influence of initial nearby continuum states in the $1^{++}$ channel. The inclusion of these states implies an effective cancellation mechanism which operates at the current and finite experimental resolution of the detectors so that one cannot distinguish between the $1^{++}$ bound-state and nearby $D{\bar{D}}^{\ast }$ continuum states with the same quantum numbers. In particular, we show that the lineshape for resolutions above 1 MeV becomes rather insensitive to the binding energy unless high statistics is considered. The very existence of the observed bumps is a mere consequence of short distance correlated $\bar{D}{D}^{\ast }$ pairs, bound or unbound. The cancellation also provides a natural explanation for a recent study reporting missing but unknown decay channels in an absolute branching ratio global analysis of the $X(3872)$.

   hep-phhep-exPRD(2021)·8 citations
2. 02*

   Flavour effects in gravitational leptogenesis

   Rome Samanta🇬🇧 · Satyabrata Datta🇮🇳

   Within the Type-I seesaw mechanism, quantum effects of the right-handed (RH) neutrinos in the gravitational background lead to an asymmetric propagation of lepton and anti-leptons which allows a Ricci scalar and neutrino Dirac-Yukawa coupling dependent chemical potential and therefore a lepton asymmetry in equilibrium. At high temperature, lepton number violating scattering processes try to maintain a dynamically generated lepton asymmetry in equilibrium. However, when the temperature drops down, the interactions become weaker, and the asymmetry freezes out. The frozen out asymmetry can act as a pre-existing asymmetry prior to the standard Fukugita-Yanagida leptogenesis phase ($T_i\sim M_i$, where $M_i$ is the mass of $i$th RH neutrino). It is then natural to consider the viability of gravitational leptogenesis for a given RH mass spectrum which is not consistent with successful leptogenesis from decays. Primary threat to this gravity-induced lepton asymmetry to be able to successfully reproduce the observed baryon-to-photon ratio is the lepton number violating washout processes at $T_i\sim M_i$. In a minimal seesaw set up with two RH neutrinos, these washout processes are strong enough to erase a pre-existing asymmetry of significant magnitude. We show that when effects of flavour on the washout processes are taken into account, the mechanism opens up the possibility of successful leptogenesis (gravitational) for a mass spectrum $M_2\gg 10^9\mathrm{GeV}\gg M_1$ with $M_1\gtrsim 6.3\times 10^6$ GeV. We then briefly discuss how, in general, the mechanism leaves its imprints on the low energy CP phases and absolute light neutrino mass scale.

   hep-phJHEP(2020)·10 citations
3. 03*

   A More Natural Composite Higgs Model

   Hsin-Chia Cheng🇺🇸 · Yi Chung🇺🇸

   Composite Higgs models provide an attractive solution to the hierarchy problem. However, many realistic models suffer from tuning problems in the Higgs potential. There are often large contributions from the UV dynamics of the composite resonances to the Higgs potential, and tuning between the quadratic term and the quartic term is required to separate the electroweak breaking scale and the compositeness scale. We consider a composite Higgs model based on the $SU(6)/Sp(6)$ coset, where an enhanced symmetry on the fermion resonances can minimize the Higgs quadratic term. Moreover, a Higgs quartic term from the collective symmetry breaking of the little Higgs mechanism can be realized by the partial compositeness couplings between elementary Standard Model fermions and the composite operators, without introducing new elementary fields beyond the Standard Model and the composite sector. The model contains two Higgs doublets, as well as several additional pseudo-Nambu-Goldstone bosons. To avoid tuning, the extra Higgs bosons are expected to be relatively light and may be probed in the future LHC runs. The deviations of the Higgs couplings and the weak gauge boson couplings also provide important tests as they are expected to be close to the current limits in this model.

   hep-phJHEP(2020)·10 citations
4. 04*

   Electroweak Physics in Inclusive Deep Inelastic Scattering at the LHeC

   Daniel Britzger🇩🇪 · Max Klein🇬🇧 · Hubert Spiesberger🇩🇪

   The proposed electron-proton collider LHeC is a unique facility where electroweak interactions can be studied with a very high precision in a largely unexplored kinematic regime of spacelike momentum transfer. We have simulated inclusive neutral- and charged-current deep-inelastic lepton proton scattering cross section data at center-of-mass energies of 1.2 and 1.3 TeV including their systematic uncertainties. Based on simultaneous fits of electroweak physics parameters and parton distribution functions, we estimate the uncertainties of Standard Model parameters as well as a number of parameters describing physics beyond the Standard Model, for instance the oblique parameters $S$, $T$, and $U$. An unprecedented precision at the sub-percent level is expected for the measurement of the weak neutral-current couplings of the light-quarks to the $Z$ boson, $g_{A/V}^{u/d}$, improving their present precision by more than an order of magnitude. The weak mixing angle can be determined with a precision of about $\Delta {\sin }^2{\theta }_{\text{W}}=\pm 0.00015$, and its scale dependence can be studied in the range between about 25 and 700 GeV. An indirect determination of the $W$-boson mass in the on-shell scheme is possible with an experimental uncertainty down to $\Delta m_W=\pm 6\text{MeV}$. We discuss how the uncertainties of such measurements in deep-inelastic scattering compare with those from measurements in the timelike domain, e.g. at the $Z$-pole, and which aspects of the electroweak interaction are unique to measurements at the LHeC, for instance electroweak parameters in charged-current interactions. We conclude that the LHeC will determine electroweak physics parameters, in the spacelike region, with unprecedented precision leading to thorough tests of the Standard Model and possibly beyond.

   hep-phhep-exEPJC(2020)·22 citations
5. 05*

   A Dark Seesaw Solution to Low Energy Anomalies: MiniBooNE, the muon $(g-2)$, and BaBar

   Asli Abdullahi🇬🇧 · Matheus Hostert🇺🇸 · Silvia Pascoli🇬🇧

   A recent update from MiniBooNE has strengthened the observed $4.8\sigma$ excess of $e$-like events. Motivated by this and other notable deviations from standard model predictions, such as the muon $(g-2)$, we propose a solution to low energy anomalies through a dark neutrino sector. The model is renormalizable and can also explain light neutrino masses with an anomaly-free and dark $U(1{)}^{\prime }$ gauge symmetry broken at the GeV scale. Large kinetic mixing leads to s-channel production of heavy neutral leptons at $e^{+}{e}^{-}$ colliders, where we point out and explain a $\gtrsim 2\sigma$ excess observed in the BaBar monophoton data. Our model is also compatible with anomalous $e$-like events seen at old accelerator experiments, as well as with an excess of double vertex signatures observed at CCFR.

   hep-phhep-exPLB(2021)·80 citations
6. 06*

   XENON1T constraints on neutrino non-standard interactions

   Siddhartha Karmakar🇮🇳 · Sujata Pandey🇮🇳

   The new XENON1T observation of dark matter-electron scattering cross-section, along with further constraining many popular dark matter models, has indicated the possibility of new physics at a low energy. We point out that this new observation also significantly constrain the neutrino non-standard interactions (NSI). We consider the NSI arising from a kinetically mixed $Z^{\prime }$ with renormalisable and dipole-like interactions with the active and light sterile neutrinos. In passing, we also address the possibility of explaining the XENON1T excess around electron recoil energy ~ 2 keV in presence of such NSI.

   hep-ph16 citations
7. 07*

   Composite Dark Matter and a horizontal symmetry

   Alexandre Carvunis🇫🇷 · Diego Guadagnoli🇫🇷 · Meril Reboud🇫🇷 · Peter Stangl🇫🇷

   We present a model of composite Dark Matter (DM), in which a new QCD-like confining "hypercolor" sector generates naturally stable hyperbaryons as DM candidates and at the same time provides mass to new weakly coupled gauge bosons $H$ that serve as DM mediators, coupling the hyperbaryons to the Standard Model (SM) fermions. By an appropriate choice of the $H$ gauge symmetry as a horizontal $SU(2{)}_h$ SM flavor symmetry, we show how the $H$ gauge bosons can be identified with the horizontal gauge bosons recently put forward as an explanation for discrepancies in rare $B$-meson decays. We find that the mass scale of the $H$ gauge bosons suggested by the DM phenomenology intriguingly agrees with the one needed to explain the rare $B$-decay discrepancies.

   hep-phJHEP(2021)·16 citations
8. 08*

   Exploring the 2HDM with Global Fits in $\text{GAMBIT}$

   Filip Rajec🇦🇺 · Wei Su🇦🇺 · Martin White🇦🇺 · Anthony G.Williams🇦🇺

   In this work, we present preliminary results of a global fit of the type-II two-Higgs-doublet model (2HDM) with the tool $\text{GAMBIT}$. Our study includes various constraints, including the theoretical constraints (unitarity, perturbativity and vacuum stability), Higgs searches at colliders, electroweak physics and flavour constraints. With the latest experimental results, our results not only confirm past studies but also go further in probing the model. We find, for example, that the measurements of $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ angular observables cannot be explained in the type-II 2HDM.

   hep-phEPJ Web Conf.(2020)·5 citations
9. 09*

   Minimal 4D Composite Higgs Models Under Current LHC Constraints

   Ethan Carragher🇦🇺 · Daniel Murnane🇦🇺 · Peter Stangl🇫🇷 · Wei Su🇦🇺 · Martin White🇦🇺 · Anthony G.Williams🇦🇺

   We present preliminary results of the first convergent global fits of several minimal composite Higgs models. Our fits are performed using the differential evolution optimisation package $\text{Diver}$. A variety of physical constraints are taken into account, including a wide range of exclusion bounds on heavy resonance production from Run 2 of the LHC. As a by-product of the fits, we analyse the collider phenomenology of the lightest new up-type and down-type resonances in the viable regions of our models, finding some low-mass resonances that can be probed in future collider searches.

   hep-phEPJ Web Conf.(2020)·0 citations
10. 10*

    Vector boson polarizations in the decay of the Standard Model Higgs

    Ezio Maina🇮🇹

    The kinematic distributions of the lepton pairs produced in the decay of the Standard Model Higgs to ZZ and WW are related to the polarization fractions of the virtual vector bosons. The full amplitude can be decomposed analytically into a sum of polarized terms. Several observables, in particular the invariant mass of two charged leptons, one from each of the bosons, and the lepton angular distribution in the vector boson center of mass are shown to be sensitive to the boson polarizations.

    hep-phPLB(2021)·30 citations
11. 11*

    NLO QCD corrections to off-shell $\text{t}\bar{\text{t}}{\text{W}}^{+}$ production at the LHC

    Ansgar Denner🇩🇪 · Giovanni Pelliccioli🇩🇪

    We present results of a computation of NLO QCD corrections to the production of an off-shell top--antitop pair in association with an off-shell ${\text{W}}^{+}$ boson in proton--proton collisions. As the calculation is based on the full matrix elements for the process $\text{p}\text{p}\to {\text{e}}^{+}{\nu }_{\text{e}}{\mu }^{-}{\bar{\nu }}_{\mu }{\tau }^{+}{\nu }_{\tau }\text{b}\bar{\text{b}}$, all off-shell, spin-correlation, and interference effects are included. The NLO QCD corrections are about $20\%$ for the integrated cross-section. Using a dynamical scale, the corrections to most distributions are at the same level, while some distributions show much larger $K$-factors in suppressed regions of phase space. We have performed a second calculation based on a double-pole approximation. While the corresponding results agree with the full calculation within few per cent for integrated cross-sections, the discrepancy can reach $10\%$ and more in regions of phase space that are not dominated by top--antitop production. As a consequence, on-shell calculations should only be trusted to this level of accuracy.

    hep-phhep-exJHEP(2020)·50 citations
12. 12*

    How to reveal the nature of three or more pentaquark states?

    C. W. Xiao🇨🇳 · J. X. Lu🇨🇳 · J. J. Wu🇨🇳 · L. S. Geng🇨🇳

    Within the chiral unitary approach and with the constraints of heavy quark spin symmetry, we study the coupled channel interactions of ${\bar{D}}^{(\ast )}{\Sigma }_c^{(\ast )}$ channels, close to whose thresholds three pentaquark-like $P_c$ states have been reported by the LHCb Collaboration. In the present work, we take into account the contributions of pion exchanges via box diagrams to the interaction potentials, and therefore lift the degeneracy in the masses of ${\bar{D}}^{\ast }{\Sigma }_c^{(\ast )}$ spin multiplets. Fitting the $J/\psi p$ invariant mass distributions in the ${\Lambda }_b^0\to J/\psi K^{-}p$ decay, we find that the LHCb pentaquark states can not be reproduced in the direct $J/\psi p$ production in the ${\Lambda }_b^0$ decay, and can only be indirectly produced in the final state interactions of the ${\Lambda }_b^0$ decay products, ${\bar{D}}^{\ast }{\Sigma }_c^{(\ast )}$, which further supports the nature of these states as $\bar{D}{\Sigma }_c$ molecules. Based on the fit results obtained, we study the partial decay widths/branching ratios to other decay channels, ${\bar{D}}^{\ast }{\Lambda }_c$, $\bar{D}{\Lambda }_c$, and ${\eta }_{c}N$, and the corresponding invariant mass distributions. The resonances with $J^P={\frac{1}{2}}^{-}$, $P_c(4312)$, $P_c(4440)$ and the one of ${\bar{D}}^{\ast }{\Sigma }_c^{\ast }$ around 4500 MeV, have large partial decay width into ${\eta }_{c}N$, and thus, can be easily seen in the ${\eta }_{c}N$ invariant mass distributions. By contrast, the states with $J^P={\frac{3}{2}}^{-}$, $P_c(4457)$, the (predicted) narrow $P_c(4380)$ and the bound state of ${\bar{D}}^{\ast }{\Sigma }_c^{\ast }$ with a mass of about 4520 MeV, do not decay into ${\eta }_{c}N$. Therefore, the ${\eta }_{c}N$ channel should be studied in future to provide further insights into the nature of these states, especially that of the $P_c(4440)$ and $P_c(4457)$.

    hep-phhep-exPRD(2020)·42 citations
13. 13*

    Reggeon Field Theory and Self Duality: Making Ends Meet

    Alex Kovner🇺🇸 · Eugene Levin🇮🇱 · Ming Li🇺🇸 · Michael Lublinsky🇮🇱

    Motivated by the question of unitarity of Reggeon Field Theory, we use the effective field theory philosophy to find possible Reggeon Field Theory Hamiltonians $H_{RFT}$. We require that $H_{RFT}$ is self dual, reproduce all known limits (dilute-dense and dilute-dilute) and exhibits all the symmetries of the JIMWLK Hamiltonian. We find a family of Hamiltonians which satisfy all the above requirements. One of these is identical in form to the so called "diamond action" discussed in \cite{diamond,Balitsky05}. However we show by explicit calculation that the so called "diamond condition" is not satisfied beyond leading perturbative order.

    hep-phnucl-thJHEP(2020)·15 citations
14. 14*

    Jet energy drop

    Pedro Cal🇳🇱 · Kyle Lee🇺🇸 · Felix Ringer🇺🇸 · Wouter J. Waalewijn🇳🇱

    We study the jet energy drop, which is the relative difference between the groomed and ungroomed jet energy or transverse momentum. It is one of the fundamental quantities that characterizes the impact of grooming on jets produced in high energy collisions. We consider three different grooming algorithms i) soft drop, ii) iterated soft drop, and iii) trimming. We carry out the resummation of large logarithms of the jet energy drop, the jet radius as well as relevant grooming parameters at next-to-leading logarithmic (NLL${}^{\prime }$) accuracy. In addition, we account for non-global and clustering logarithms, and determine the next-to-leading order corrections. For soft drop we perform a joint resummation of the jet energy drop and the groomed jet radius, which is necessary to achieve the correct all-order structure of the cross section, in particular for the Sudakov-safe case of soft drop with $\beta =0$. We present numerical results for LHC energies and compare to Pythia simulations as well as CMS data. Our factorization framework predicts the onset of nonperturbative effects in the jet energy distribution, in line with what we find in Pythia. The jet energy drop observables stand out because they only probe soft radiation, making them ideal candidates for the tuning of parton shower Monte Carlo event generators and for probing medium effects in heavy-ion collisions.

    hep-phJHEP(2020)·17 citations
15. 15*

    Production of $f_2(1270)$ meson in $pp$ collisions at the LHC via gluon-gluon fusion in the $k_t$-factorization approach

    Piotr Lebiedowicz🇵🇱 · Antoni Szczurek🇵🇱

    We calculate inclusive cross section for $f_2(1270)$ tensor meson production via color singlet gluon-gluon fusion in the $k_t$-factorization approach with unintegrated gluon distribution functions (UGDFs). The process may be potentially interesting in the context of searches for saturation effects. The energy-momentum tensor, equivalent to helicity-2 coupling, and helicity-0 coupling are used for the $g^{\ast }{g}^{\ast }\to f_2(1270)$ vertex. Two somewhat different parametrizations of helicity-2 and helicity-0 tensorial structure from the literature are used in our calculations. Some parameters are extracted from $\gamma \gamma \to f_2(1270)\to \pi \pi$ reactions. Different modern UGDFs from the literature are used. The results strongly depend on the parametrization of the $g^{\ast }{g}^{\ast }\to f_2(1270)$ form factor. Our results for transverse momentum distributions of $f_2$ are compared to preliminary ALICE data. We can obtain agreement with the data only at larger $f_2(1270)$ transverse momenta only for some parametrizations of the $g^{\ast }{g}^{\ast }\to f_2(1270)$ form factor. No obvious sign of the onset of saturation is possible. At low transverse momenta one needs to include also the $\pi \pi$ final-state rescattering. The agreement with the ALICE data can be obtained by adjusting probability of formation and survival of $f_2(1270)$ in a harsh quark-gluon and multipion environment. The pomeron-pomeron fusion mechanism is discussed in addition and results are quantified.

    hep-phPLB(2020)·4 citations
16. 16*

    Excitations of elementary fermions in gauge Higgs theories

    Jeff Greensite🇺🇸

    Static quark-antiquark states in QCD, at finite quark separation, have a spectrum of metastable states corresponding to string-like excitations of the gauge field. In this article I suggest that there may also exist an excitation spectrum of heavy fermions in some gauge Higgs theories deep in the Higgs phase. In this situation there are no color electric flux tubes connecting quarks with antiquarks. There may, nonetheless, exist stable excitations of the bosonic fields surrounding an isolated fermion, below the particle production threshold. I present numerical evidence indicating the existence of such excitations in an SU(3) gauge Higgs theory, with the scalar field in the fundamental representation of the gauge group.

    ↳ hep-lathep-phhep-thPRD(2020)·15 citations
17. 17*

    Anomalous $U(1)$ Gauge Bosons as Light Dark Matter in String Theory

    Luis A. Anchordoqui🇺🇸 · Ignatios Antoniadis🇫🇷 · Karim Benakli🇫🇷 · Dieter Lust🇩🇪

    Present experiments are sensitive to very weakly coupled extra gauge symmetries which motivates further investigation of their appearance in string theory compactifications and subsequent properties. We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale saturates the current LHC limit and that the theory is weakly coupled, we show that (anomalous) $U(1)$ gauge bosons which propagate into the bulk are compelling light dark matter candidates. We comment on the possible relevance of the $U(1)$ gauge bosons, which are universal in intersecting D-brane models, to the observed $3\sigma$ excess in XENON1T.

    ↳ hep-thastro-ph.COhep-phPLB(2020)·20 citations
18. 18*

    Constraints on a mixed model of dark matter particles and primordial black holes from the Galactic 511 keV line

    Rong-Gen Cai🇨🇳 · Yu-Chen Ding🇨🇳 · Xing-Yu Yang🇨🇳 · Yu-Feng Zhou🇨🇳

    The galactic 511 keV gamma-ray line has been observed since 1970's, and was identified as the result of electron-positron annihilation, but the origin of such positrons is still not clear. Apart from the astrophysical explanations, the possibilities that such positrons come from dark matter (DM) annihilation are also widely studied. Primordial black hole (PBH) is also an extensively studied candidate of DM. If PBHs exist, the DM particles may be gravitationally bound to the PBHs and form halo around PBHs with density spikes. DM annihilation in these density spikes can enhance the production rate of positrons from DM particles, but the signal morphology is similar to the decaying DM. We consider such a mixed model consisting of DM particles and PBHs and obtain the upper limit from the data of 511 keV gamma-ray line from INTEGRAL/SPI on the decaying component of DM particles and the constraint on the PBH abundance. These constraints are general and independent of particle DM models. For the mixed model consisting of excited DM and PBHs, the constraints on the PBH abundance can be down to $O(10^{-17})$ for DM particle with mass around $1\mathrm{TeV}$, which is more stringent than that obtained from the extragalactic gamma-ray background.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·59 citations
19. 19*

    Spin and polarisation dependent LCFA rates for nonlinear Compton and Breit-Wheeler processes

    D. Seipt🇩🇪 · B. King🇬🇧

    In this paper we derive and discuss the completely spin- and photon-polarisation dependent probability rates for nonlinear Compton scattering and nonlinear Breit-Wheeler pair production. The locally constant field approximation, which is essential for applications in plasma-QED simulation codes, is rigorously derived from the strong-field QED matrix elements in the Furry picture for a general plane-wave background field. We discuss important polarisation correlation effects in the spectra of both processes. Asymptotic limits for both small and large values of $\chi$ are derived and their spin/polarisation dependence is discussed.

    ↳ physics.plasm-phhep-phPRA(2020)·85 citations
20. 20*

    Pseudoscalar glueballs in the Klebanov-Strassler Theory

    Dmitry Melnikov🇧🇷 · Cornélio Rodrigues Filho🇧🇷

    In this paper we describe a pseudoscalar subsector of the Klebanov-Strassler model. This subsector completes the holographic reconstruction of the spectrum of the lowest-lying glueball states, which are singlet under the global symmetry group $SU(2)\times SU(2)$. We derive the linearized supergravity equations for the pseudoscalar fluctuations and analyze their spectrum. The system of equation is shown to be compatible with six eigenmodes, as expected from supersymmetry. Our numerical analysis allows to reliably extract four of the corresponding towers. Their values match well the eigenvalues of the $0^{++}$ scalar states known from an earlier work. Assuming the masses of $0^{++}$ as a reference, we compare the lightest states of the holographic spectrum with lattice calculations in the quenched QCD at $N_c=3$ and $N_c=\infty$.

    ↳ hep-thhep-lathep-phJHEP(2021)·6 citations
21. 21*

    Quantifying the effect of cooled initial conditions on cosmic string network evolution

    J. R. C. C. C. Correia🇵🇹 · C. J. A. P. Martins🇵🇹

    Quantitative studies of the evolution and cosmological consequences of networks of cosmic strings (or other topological defects) require a combination of numerical simulations and analytic modeling with the velocity-dependent one-scale (VOS) model. In previous work, we demonstrated that a GPU-accelerated code for local Abelian-Higgs string networks enables a statistical separation of key dynamical processes affecting the evolution of the string networks and thus a precise calibration of the VOS model. Here we further exploit this code in a detailed study of two important aspects connecting the simulations with the VOS model. First, we study the sensitivity of the model calibration to the presence (or absence) of thermal oscillations due to high gradients in the initial conditions. This is relevant since in some Abelian-Higgs simulations described in the literature a period of artificial (unphysical) dissipation---usually known as cooling---is introduced with the goal of suppressing these oscillations and accelerating the convergence to scaling. We show that a small amount of cooling has no statistically significant impact on the VOS model calibration, while a longer dissipation period does have a noticeable effect. Second, in doing this analysis we also introduce an improved Markov Chain Monte Carlo based pipeline for calibrating the VOS model, Comparison to our previous bootstrap based pipeline shows that the latter accurately determined the best-fit values of the VOS model parameter, but underestimated the uncertainties in some of the parameters. Overall, our analysis shows that the calibration pipeline is robust and can be applied to future much larger field theory simulations.

    ↳ astro-ph.COhep-phphysics.comp-phPRD(2020)·17 citations
22. 22*

    Search for composite dark matter with optically levitated sensors

    Fernando Monteiro🇺🇸 · Gadi Afek🇺🇸 · Daniel Carney🇺🇸 · Gordan Krnjaic🇺🇸 · Jiaxiang Wang🇺🇸 · David C. Moore🇺🇸

    Results are reported from a search for a class of composite dark matter models with feeble, long-range interactions with normal matter. We search for impulses arising from passing dark matter particles by monitoring the mechanical motion of an optically levitated nanogram mass over the course of several days. Assuming such particles constitute the dominant component of dark matter, this search places upper limits on their interaction with neutrons of ${\alpha }_n\le 1.2\times 10^{-7}$ at 95\% confidence for dark matter masses between 1--10 TeV and mediator masses $m_{\varphi }\le 0.1$ eV. Due to the large enhancement of the cross-section for dark matter to coherently scatter from a nanogram mass ($\sim 10^{29}$ times that for a single neutron) and the ability to detect momentum transfers as small as $\sim$200 MeV/c, these results provide sensitivity to certain classes of composite dark matter models that substantially exceeds existing searches, including those employing kg-scale or ton-scale targets. Extensions of these techniques can enable directionally-sensitive searches for a broad class of previously inaccessible heavy dark matter candidates.

    ↳ hep-exastro-ph.COhep-phphysics.ins-detPRL(2020)·111 citations
23. 23*

    First branching fraction measurement of the suppressed decay ${\Xi }_c^0\to {\pi }^{-}{\Lambda }_c^{+}$

    LHCb collaboration: R. Aaij🇳🇱 · C. Abellán Beteta🇨🇭 · T. Ackernley🇬🇧 · B. Adeva🇪🇸 · M. Adinolfi🇬🇧 · H. Afsharnia🇫🇷 · C.A. Aidala🇺🇸 · S. Aiola🇮🇹 · Z. Ajaltouni🇫🇷 · S. Akar🇺🇸 · J. Albrecht🇩🇪 · F. Alessio🇨🇭 and 960 other authors

    The ${\Xi }_c^0$ baryon is unstable and usually decays into charmless final states by the $c\to su\overline{d}$ transition. It can, however, also disintegrate into a ${\pi }^{-}$ meson and a ${\Lambda }_c^{+}$ baryon via $s$ quark decay or via $cs\to dc$ weak scattering. The interplay between the latter two processes governs the size of the branching fraction $\mathcal{B}$$({\Xi }_c^0\to {\pi }^{-}{\Lambda }_c^{+})$, first measured here to be $(0.55\pm 0.02\pm 0.18)$%, where the first uncertainty is statistical and second systematic. This result is compatible with the larger of the theoretical predictions that connect models of hyperon decays using partially conserved axial currents and SU(3) symmetry with those involving the heavy-quark expansion and heavy-quark symmetry. In addition, the branching fraction of the normalization channel, $\mathcal{B}({\Xi }_c^{+}\to p{K}^{-}{\pi }^{+})=(1.135\pm 0.002\pm 0.387)$% is measured.

    ↳ hep-exhep-phPRD(2020)·40 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.