Mon·Dec 5, 2016Monday·December 5, 2016

1. 01*

   Measuring the CP property of Higgs coupling to tau leptons in the VBF channel at the LHC

   Tao Han🇺🇸 · Satyanarayan Mukhopadhyay🇺🇸 · Biswarup Mukhopadhyaya🇮🇳 · Yongcheng Wu🇨🇳

   We study the prospects of measuring the CP property of the Higgs ($h$) coupling to tau leptons using the vector boson fusion (VBF) production mode at the high-luminosity LHC. Utilizing the previously proposed angle between the planes spanned by the momentum vectors of the $({\pi }^{+}{\pi }^0)$ and $({\pi }^{-}{\pi }^0)$ pairs originating in ${\tau }^{\pm }$ decays as the CP-odd observable, we perform a detailed Monte Carlo analysis, taking into account the relevant standard model backgrounds, as well as detector resolution effects. We find that excluding a pure CP-odd coupling hypothesis requires $\mathcal{O}(400{\mathrm{fb}}^{-1})$ luminosity at the 14 TeV LHC, and values of the CP-mixing angle larger than about $25^{\circ }$ can be excluded at $95\%$ confidence level using $3{\mathrm{ab}}^{-1}$ data. It is observed that the uncertainty in the angular resolution of the neutral pion momenta does not constitute a significant hurdle. Achieving a signal to background ratio ($S/B$) close to one, while keeping a high enough signal yield required to study the angular distributions selects out VBF as a promising mode to probe the CP nature of the $h\tau \tau$ coupling, with gluon fusion suffering from a low $S/B$, and the $W^{\pm }h/Zh$ mode (with leptonically decaying $W^{\pm }/Z$) having a much smaller signal rate.

   hep-phhep-exJHEP(2017)·15 citations
2. 02*

   Hydrogen Axion Star: Metallic Hydrogen Bound to a QCD Axion BEC

   Yang Bai🇺🇸 · Vernon Barger🇺🇸 · Joshua Berger🇺🇸

   As a cold dark matter candidate, the QCD axion may form Bose-Einstein condensates, called axion stars, with masses around $10^{-11}{M}_{\odot }$. In this paper, we point out that a brand new astrophysical object, a Hydrogen Axion Star (HAS), may well be formed by ordinary baryonic matter becoming gravitationally bound to an axion star. We study the properties of the HAS and find that the hydrogen cloud has a high pressure and temperature in the center and is likely in the liquid metallic hydrogen state. Because of the high particle number densities for both the axion star and the hydrogen cloud, the feeble interaction between axion and hydrogen can still generate enough internal power, around $10^{13}\text{mbox}W\times (m_a/5\text{mbox}meV{)}^4$, to make these objects luminous point sources. High resolution ultraviolet, optical and infrared telescopes can discover HAS via black-body radiation.

   hep-phastro-ph.COastro-ph.HEJHEP(2016)·37 citations
3. 03*

   Subleading Power Corrections for N-Jettiness Subtractions

   Ian Moult🇺🇸 · Lorena Rothen🇩🇪 · Iain W. Stewart🇺🇸 · Frank J. Tackmann🇩🇪 · Hua Xing Zhu🇺🇸

   The $N$-jettiness observable ${\mathcal{T}}_N$ provides a way of describing the leading singular behavior of the $N$-jet cross section in the $\tau ={\mathcal{T}}_N/Q\to 0$ limit, where $Q$ is a hard interaction scale. We consider subleading power corrections in the $\tau \ll 1$ expansion, and employ soft-collinear effective theory to obtain analytic results for the dominant ${\alpha }_s\tau \ln \tau$ and ${\alpha }_s^2\tau {\ln }^3\tau$ subleading terms for thrust in $e^{+}{e}^{-}$ collisions and $0$-jettiness for $q\bar{q}$-initiated Drell-Yan-like processes at hadron colliders. These results can be used to significantly improve the numerical accuracy and stability of the $N$-jettiness subtraction technique for performing fixed-order calculations at NLO and NNLO. They reduce the size of missing power corrections in the subtractions by an order of magnitude. We also point out that the precise definition of $N$-jettiness has an important impact on the size of the power corrections and thus the numerical accuracy of the subtractions. The sometimes employed definition of $N$-jettiness in the hadronic center-of-mass frame suffers from power corrections that grow exponentially with rapidity, causing the power expansion to deteriorate away from central rapidity. This degradation does not occur for the original $N$-jettiness definition, which explicitly accounts for the boost of the Born process relative to the frame of the hadronic collision, and has a well-behaved power expansion throughout the entire phase space. Integrated over rapidity, using this $N$-jettiness definition in the subtractions yields another order of magnitude improvement compared to employing the hadronic-frame definition.

   hep-phPRD(2017)·158 citations
4. 04*

   ${\mathbf{\mu }}^{-}$- ${\mathbf{e}}^{+}$ Conversion from Short-Range Operators

   Tanja Geib🇩🇪 · Alexander Merle🇩🇪

   We present a detailed discussion of the lepton flavour and number violating conversion of bound muons into positrons. This process is a viable alternative to neutrinoless double beta decay and, given that experiments on ordinary ${\mu }^{-}$- $e^{-}$ conversion are expected to improve their sensitivities by several orders of magnitude in the coming years, we can also assume the limit on ${\mu }^{-}$- $e^{+}$ conversion to improve by roughly the same factor. We discuss how new physics at a high scale can lead to short-range contributions to this conversion process and we present one explicit case in great detail (the single one for which the corresponding nuclear matrix element is presently known). The main goal of our discussion is to make the respective computation accessible to the particle physics community, so that promising models can be investigated while the nuclear physics community can simultaneously advance the computation of nuclear matrix elements. Given the progress to be expected on the experimental side, it may even be possible that lepton number violation in the $e\mu$-sector is discovered by ${\mu }^{-}$- $e^{+}$ conversion before neutrinoless double beta decay can show its existence in the $ee$-sector.

   hep-phhep-exnucl-thPRD(2017)·21 citations
5. 05*

   Low-mass neutralino dark matter in supergravity scenarios: phenomenology and naturalness

   M. Peiro🇪🇸 · S. Robles🇪🇸

   The latest experimental results from the LHC and dark matter (DM) searches suggest that the parameter space allowed in supersymmetric theories is subject to strong reductions. These bounds are especially constraining for scenarios entailing light DM particles. Previous studies have shown that light neutralino DM in the Minimal Supersymmetric Standard Model (MSSM), with parameters defined at the electroweak scale, is still viable when the low energy spectrum of the model features light sleptons, in which case, the relic density constraint can be fulfilled. In view of this, we have investigated the viability of light neutralinos as DM candidates in the MSSM, with parameters defined at the grand unification scale. We have analysed the optimal choices of non-universalities in the soft supersymmetry-breaking parameters for both, gauginos and scalars, in order to avoid the stringent experimental constraints. We show that light neutralinos, with a mass as low as 25 GeV, are viable in supergravity scenarios if the gaugino mass parameters at high energy are very non universal, while the scalar masses can remain of the same order. These scenarios typically predict a very small cross section of neutralinos off protons and neutrons, thereby being very challenging for direct detection experiments. However, a potential detection of smuons and selectrons at the LHC, together with a hypothetical discovery of a gamma-ray signal from neutralino annihilations in dwarf spheroidal galaxies could shed light on this kind of solutions. Finally, we have investigated the naturalness of these scenarios, taking into account all the potential sources of tuning. Besides the electroweak fine-tuning, we have found that the tuning to reproduce the correct DM relic abundance and that to match the measured Higgs mass can also be important when estimating the total degree of naturalness.

   hep-phastro-ph.COJCAP(2017)·10 citations
6. 06*

   Thermal Resummation and Phase Transitions

   David Curtin🇺🇸 · Patrick Meade🇺🇸 · Harikrishnan Ramani🇺🇸

   The consequences of phase transitions in the early universe are becoming testable in a variety of manners, from colliders physics to gravitational wave astronomy. In particular one phase transition we know of, the Electroweak Phase Transition (EWPT), could potentially be first order in BSM scenarios and testable in the near future. If confirmed this could provide a mechanism for Baryogenesis, which is one of the most important outstanding questions in physics. To reliably make predictions it is necessary to have full control of the finite temperature scalar potentials. However, as we show the standard methods used in BSM physics to improve phase transition calculations, resumming hard thermal loops, introduces significant errors into the scalar potential. In addition, the standard methods make it impossible to match theories to an EFT description reliably. In this paper we define a thermal resummation procedure based on Partial Dressing (PD) for general BSM calculations of phase transitions beyond the high-temperature approximation. Additionally, we introduce the modified Optimized Partial Dressing (OPD) procedure, which is numerically nearly as efficient as old incorrect methods, while yielding identical results to the full PD calculation. This can be easily applied to future BSM studies of phase transitions in the early universe. As an example, we show that in unmixed singlet scalar extensions of the SM, the (O)PD calculations make new phenomenological predictions compared to previous analyses. An important future application is the study of EFTs at finite temperature.

   hep-phastro-ph.COhep-thEPJC(2018)·204 citations
7. 07*

   Anatomy of the Inert Two Higgs Doublet Model in the light of the LHC and non-LHC Dark Matter Searches

   Alexander Belyaev🇬🇧 · Giacomo Cacciapaglia🇫🇷 · Igor P. Ivanov🇵🇹 · Felipe Rojas🇨🇱 · Marc Thomas🇬🇧

   The inert Two Higgs Doublet Model (i2HDM) is a theoretically well-motivated example of a minimal consistent Dark Matter(DM) model which provides mono-jet, mono-Z, mono-Higgs and Vector-Boson-Fusion+Missing Transverse Momentum signatures at the LHC, complemented by signals in direct and indirect DM search experiments. In this paper we have performed a detailed analysis of the constraints in the full 5D parameter space of the i2HDM, coming from perturbativity, unitarity, electroweak precision data, Higgs data from LHC, DM relic density, direct/indirect DM detection and LHC mono-jet analysis, as well as implications of experimental LHC studies on disappearing charged tracks relevant to high DM mass region. We demonstrate the complementarity of the above constraints and present projections for future LHC data and direct DM detection experiments to probe further i2HDM parameter space. The model is implemented into the CalcHEP and micrOMEGAs packages, which are publicly available at the HEPMDB database, and is ready for a further exploration in the context of the LHC, relic density and DM direct detection.

   hep-phPRD(2018)·256 citations
8. 08*

   Top and bottom tensor couplings from a color octet scalar

   Roberto Martinez🇨🇴 · German Valencia🇦🇺

   We compute the one-loop contributions from a color octet scalar to the tensor anomalous couplings of top and bottom quarks to gluons, photons and W bosons. We use known constraints on the parameters of the model to compare the predicted size of these couplings with existing phenomenological constraints.

   hep-phPRD(2017)·17 citations
9. 09*

   Deciphering Majorana nature of sub-eV neutrinos by using their quantum statistical property

   C. S. Kim🇰🇷 · Dibyakrupa Sahoo🇰🇷

   Neutrinos are the only known elementary fermions that can exhibit Majorana nature. As per the "practical Dirac-Majorana confusion theorem" it is impossible to distinguish between Dirac and Majorana neutrinos via any kinematic tests when their masses are very small. However, it is also well known that Majorana neutrino and anti-neutrino present in the final state must obey the Fermi-Dirac statistics, irrespective of how small the mass of neutrino is. We propose a new method to search for Majorana neutrinos by exploiting their quantum statistical property. We analyse `effective' three-body decays of the kind $X\to Y\nu \overline{\nu }$ (e.g.\ $X\left[B^0\right]\to {\pi }^{+}(\to {\mu }^{+}{\nu }_{\mu }){\mu }^{-}{\overline{\nu }}_{\mu }\equiv Y\left[{\mu }^{+}{\mu }^{-}\right]{\nu }_{\mu }{\overline{\nu }}_{\mu }$), with 4-momenta of $X$ and $Y$ experimentally known, such that the 4-momenta of both neutrino and anti-neutrino can be deduced. For Majorana neutrinos the distribution of events in the `effective' Dalitz plot for such a well chosen process would be fully symmetric under exchange of the neutrino and anti-neutrino. Unlike the neutrinoless double-beta decay or other lepton-number violating modes, this distinction between Majorana and Dirac neutrinos survives even in the almost massless neutrino limit due to the quantum statistical property.

   hep-ph2 citations
10. 10*

    Searching for New Physics in Scalar Top-Pair Resonance

    Jérémie Quevillon🇬🇧

    We consider the effects in the production via gluon fusion in LHC collisions of one or two spin-zero new resonant particles $\Phi$ that decay into a top quark pair. We revisit previous analyses of the interferences between the heavy-fermion loop-induced $gg\to \Phi \to t\bar{t}$ signal and the continuum QCD background $gg\to t\bar{t}$. We show that in the presence of standard model fermions only in the $gg\to \Phi$ loops, the interference effect is destructive causing a dip in the $t\bar{t}$ mass distribution. Including New Physics such as additional vector-like quarks leads to a totally different picture as the line-shape can be distorted by peaks and dips. For the time being, the absence of such effects in ATLAS and CMS data constrain models of the production and decays of the $\Phi$ state(s).

    hep-phhep-ex1 citation
11. 11*

    On the $b$-quark running mass in QCD and the SM

    A.V. Bednyakov🇷🇺 · B.A. Kniehl🇩🇪 · A.F. Pikelner🇩🇪 · O.L. Veretin🇩🇪

    We consider electroweak corrections to the relation between the running $\overline{\mathrm{MS}}$ mass $m_b$ of the $b$ quark in the five-flavor QCD$\times$QED effective theory and its counterpart in the Standard Model (SM). As a bridge between the two parameters, we use the pole mass $M_b$ of the $b$ quark, which can be calculated in both models. The running mass is not a fundamental parameter of the SM Lagrangian, but the product of the running Yukawa coupling $y_b$ and the Higgs vacuum expectation value. Since there exist different prescriptions to define the latter, the relations considered in the paper involve a certain amount of freedom. All the definitions can be related to each other in perturbation theory. Nevertheless, we argue in favor of a certain gauge-independent prescription and provide a relation which can be directly used to deduce the value of the Yukawa coupling of the $b$ quark at the electroweak scale from its effective QCD running mass. This approach allows one to resum large logarithms $\ln (m_b/M_t)$ systematically. Numerical analysis shows that, indeed, the corrections to the proposed relation are much smaller than those between $y_b$ and $M_b$.

    hep-phNPB(2017)·34 citations
12. 12*

    The quark propagator in QCD and $G_2$ QCD

    Romain Contant🇦🇹 · Markus Q. Huber🇦🇹

    QCD-like theories provide testing grounds for truncations of functional equations at non-zero density, since comparisons with lattice results are possible due to the absence of the sign problem. As a first step towards such a comparison, we determine for QCD and $G_2$ QCD the chiral and confinement/deconfinement transitions from the quark propagator Dyson-Schwinger equation at zero chemical potential by calculating the chiral and dual chiral condensates, respectively.

    hep-phEPJ Web Conf.(2017)·4 citations
13. 13*

    Radiative corrections and instability of large Q-Balls

    A.V. Kovtun🇷🇺 · E.Ya. Nugaev🇷🇺

    We discuss stability of Q-balls interacting with fermions in theory with small coupling constant g. We argue that for configurations with large global U(1)-charge Q the problem of classical stability becomes more subtle. For example, in model with flat direction there is maximal value of charge for stable solutions with Q~1/g^4. We study origin of additional instability and discuss possible ways to avoid it.

    hep-phhep-thMod.Phys.Lett.A(2017)·3 citations
14. 14*

    Charged-lepton decays from soft flavour violation

    E.H. Aeikens🇦🇹 · W. Grimus🇦🇹 · L. Lavoura🇵🇹

    We consider a two-Higgs-doublet extension of the Standard Model, with three right-handed neutrino singlets and the seesaw mechanism, wherein all the Yukawa-coupling matrices are lepton flavour-diagonal and lepton flavour violation is soft, originating solely in the non-flavour-diagonal Majorana mass matrix of the right-handed neutrinos. We consider the limit $m_R\to \infty$ of this model, where $m_R$ is the seesaw scale. We demonstrate that there is a region in parameter space where the branching ratios of all five charged-lepton decays ${\ell }_1^{-}\to {\ell }_2^{-}{\ell }_3^{+}{\ell }_3^{-}$ are close to their experimental upper bounds, while the radiative decays ${\ell }_1^{-}\to {\ell }_2^{-}\gamma$ are invisible because their branching ratios are suppressed by $m_R^{-4}$. We also consider the anomalous magnetic moment of the muon and show that in our model the contributions from the extra scalars, both charged and neutral, can remove the discrepancy between its experimental and theoretical values.

    hep-phPLB(2017)·4 citations
15. 15*

    Connecting Dark Matter Annihilation to the Vertex Functions of Standard Model Fermions

    Jason Kumar🇺🇸 · Christopher Light🇺🇸

    We consider scenarios in which dark matter is a Majorana fermion which couples to Standard Model fermions through the exchange of charged mediating particles. The matrix elements for various dark matter annihilation processes are then related to one-loop corrections to the fermion-photon vertex, where dark matter and the charged mediators run in the loop. In particular, in the limit where Standard Model fermion helicity mixing is suppressed, the cross section for dark matter annihilation to various final states is related to corrections to the Standard Model fermion charge form factor. These corrections can be extracted in a gauge-invariant manner from collider cross sections. Although current measurements from colliders are not precise enough to provide useful constraints on dark matter annihilation, improved measurements at future experiments, such as the International Linear Collider, could improve these constraints by several orders of magnitude, allowing them to surpass the limits obtainable by direct observation.

    hep-phJCAP(2017)·3 citations
16. 16*

    Can nonstandard interactions jeopardize the hierarchy sensitivity of DUNE ?

    K. N. Deepthi🇮🇳 · Srubabati Goswami🇮🇳 · Newton Nath🇮🇳

    We study the effect of non-standard interactions (NSIs) on the propagation of neutrinos through the Earth matter and how it affects the hierarchy sensitivity of the DUNE experiment. We emphasize on the special case when the diagonal NSI parameter ${ϵ}_{ee}=-1$, nullifying the standard matter effect. We show that, if in addition, CP violation is maximal then this gives rise to an exact intrinsic hierarchy degeneracy in the appearance channel, irrespective of the baseline and energy. Introduction of off-diagonal NSI parameter, ${ϵ}_{e\tau }$, shifts the position of this degeneracy to a different ${ϵ}_{ee}$. Moreover the unknown magnitude and phases of the off-diagonal NSI parameters can give rise to additional degeneracies. Overall, given the current model independent limits on NSI parameters, the hierarchy sensitivity of DUNE can get seriously impacted. However, a more precise knowledge on the NSI parameters, specially ${ϵ}_{ee}$, can give rise to an improved sensitivity. Alternatively, if NSI exists in nature, and still DUNE shows hierarchy sensitivity, certain ranges of the NSI parameters can be excluded. Additionally, we briefly discussed the implications of ${ϵ}_{ee}=-1$ (in the Earth) on MSW effect in the Sun.

    hep-phPRD(2017)·60 citations
17. 17*

    Exponential reduction of finite volume effects with twisted boundary conditions

    Aleksey Cherman🇺🇸 · Srimoyee Sen🇺🇸 · Michael L. Wagman🇺🇸 · Laurence G. Yaffe🇺🇸

    Flavor-twisted boundary conditions can be used for exponential reduction of finite volume artifacts in flavor-averaged observables in lattice QCD calculations with $SU(N_f)$ light quark flavor symmetry. Finite volume artifact reduction arises from destructive interference effects in a manner closely related to the phase averaging which leads to large $N_c$ volume independence. With a particular choice of flavor-twisted boundary conditions, finite volume artifacts for flavor-singlet observables in a hypercubic spacetime volume are reduced to the size of finite volume artifacts in a spacetime volume with periodic boundary conditions that is four times larger.

    ↳ hep-lathep-phhep-thPRD(2017)·16 citations
18. 18*

    A Universe Without Dark Energy: Cosmic Acceleration from Dark Matter-Baryon Interactions

    Lasha Berezhiani🇺🇸 · Justin Khoury🇺🇸 · Junpu Wang🇺🇸

    Cosmic acceleration is widely believed to require either a source of negative pressure (i.e., dark energy), or a modification of gravity, which necessarily implies new degrees of freedom beyond those of Einstein gravity. In this paper we present a third possibility, using only dark matter and ordinary matter. The mechanism relies on the coupling between dark matter and ordinary matter through an effective metric. Dark matter couples to an Einstein-frame metric, and experiences a matter-dominated, decelerating cosmology up to the present time. Ordinary matter couples to an effective metric that depends also on the DM density, in such a way that it experiences late-time acceleration. Linear density perturbations are stable and propagate with arbitrarily small sound speed, at least in the case of `pressure' coupling. Assuming a simple parametrization of the effective metric, we show that our model can successfully match a set of basic cosmological observables, including luminosity distance, BAO measurements, angular-diameter distance to last scattering {\it etc.} For the growth history of density perturbations, we find an intriguing connection between the growth factor and the Hubble constant. To get a growth history similar to the $\Lambda$CDM prediction, our model predicts a higher $H_0$, closer to the value preferred by direct estimates. On the flip side, we tend to overpredict the growth of structures whenever $H_0$ is comparable to the Planck preferred value. The model also tends to predict larger redshift-space distortions at low redshift than $\Lambda$CDM.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2017)·32 citations
19. 19*

    Effective field theory approach to the gravitational two-body dynamics, at fourth post-Newtonian order and quintic in the Newton constant

    Stefano Foffa (Geneva U., Dept. Theor. Phys. and Geneva U., CAP)🇨🇭 · Pierpaolo Mastrolia (Padua U. and INFN, Padua)🇮🇹 · Riccardo Sturani (IIP, Natal)🇧🇷 · Christian Sturm (Wurzburg U.)🇩🇪

    Working within the post-Newtonian (PN) approximation to General Relativity, we use the effective field theory (EFT) framework to study the conservative dynamics of the two-body motion at fourth PN order, at fifth order in the Newton constant. This is one of the missing pieces preventing the computation of the full Lagrangian at fourth PN order using EFT methods. We exploit the analogy between diagrams in the EFT gravitational theory and 2-point functions in massless gauge theory, to address the calculation of 4-loop amplitudes by means of standard multi-loop diagrammatic techniques. For those terms which can be directly compared, our result confirms the findings of previous studies, performed using different methods.

    ↳ gr-qchep-phhep-thPRD(2017)·163 citations
20. 20*

    Charged pions tagged with polarized photons probing strong CP violation in a chiral-imbalance medium

    Mamiya Kawaguchi🇯🇵 · Masayasu Harada🇯🇵 · Shinya Matsuzaki🇯🇵 · Ruiwen Ouyang🇨🇳

    It is expected that in a hot QCD system, a local parity-odd domain can be produced due to nonzero chirality, which is induced from the difference of winding numbers carried by the gluon topological configuration (QCD sphaleron). This local domain is called the chiral-imbalance medium characterized by nonzero chiral chemical potential, which can be interpreted as the time variation of the strong CP phase. We find that the chiral chemical potential generates the parity breaking term in the electromagnetic form factor of charged pions. Heavy ion collision experiments could observe the phenomenological consequence of this parity-odd form factor through the elastic scattering of a pion and a photon in the medium. Then we quantify the asymmetry rate of the parity violation by measuring the polarization of the photon associated with the pion, and discuss how it could be measured in a definite lab frame. We roughly estimate the typical size of the asymmetry, just by picking up the pion resonant process, and find that the signal can be sufficiently larger than possible background events from parity-breaking electroweak process. Our findings might provide a novel possibility to make a manifest detection for the remnant of the strong CP violation.

    ↳ nucl-thhep-phnucl-exPRC(2017)·12 citations
21. 21*

    Critical Schwinger pair production II - universality in the deeply critical regime

    Holger Gies🇩🇪 · Greger Torgrimsson🇩🇪

    We study electron-positron pair production by spatially inhomogeneous electric fields. Depending on the localization of the field, a critical point (critical surface) exists in the space of field configurations where the pair production probability vanishes. Near criticality, pair production exhibits universal properties similar to those of continuous phase transitions. We extend results previously obtained in the semi-classical (weak-field) critical regime to the deeply critical regime for arbitrary peak field strength. In this regime, we find an enhanced universality, featuring a unique critical exponent $\beta =3$ for all sufficiently localized fields. For a large class of field profiles, we also compute the non-universal amplitudes.

    ↳ hep-thcond-mat.stat-mechhep-phPRD(2017)·30 citations
22. 22*

    Top quark pair asymmetries

    Filomena Sopkova🇸🇰

    In this article, we study top quark pair charge, energy and incline asymmetry at parton level using Powheg Monte-Carlo generator.

    ↳ hep-exhep-ph0 citations
23. 23*

    Conditions for the existence of stable strange quark matter

    Nicola Andrea Dondi🇮🇹 · Alessandro Drago🇮🇹 · Giuseppe Pagliara🇮🇹

    We discuss the possible existence of absolutely stable strange quark matter within three different types of chiral models. We will show that confinement plays a crucial role in determining the conditions for the Bodmer-Witten hypothesis to hold true. We discuss also which are the phenomenological signatures, related to measurements of masses and radii of compact stars, which would prove the existence of strange quark stars.

    ↳ nucl-thastro-ph.HEhep-phEPJ Web Conf.(2017)·7 citations
24. 24*

    Precision long-term measurements of beta-decay-rate ratios in a controlled environment

    S. D. Bergeson🇺🇸 · J. B. Peatross🇺🇸 · M. Ware🇺🇸

    We report on measurements of relative beta-decay rates of Na-22, Cl-36, Co-60, Sr-90, Cs-137 monitored for more than one year. The radioactive samples are mounted in an automated sample changer that sequentially positions the five samples in turn, with high spatial precision, in front of each of four Geiger-Müller tubes. The sample wheel, detectors, and associated electronics are housed inside a sealed chamber held at constant absolute pressure, humidity, and temperature to isolate the experiment from environmental variations. The statistical uncertainty in the count rate approaches a few times 0.01% with two weeks of averaging. Other sources of error are on a similar scale. The data are analyzed in variety of ways, comparing count rates of the various samples on one or more detectors, and comparing count rates of a particular sample across multiple detectors. We observe no statistically significant variations in the ratios of decay rates, either annual or at higher-frequency, at a level above 0.01%.

    ↳ nucl-exhep-phphysics.ins-detPLB(2017)·3 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.