Tue·Aug 11, 2015Tuesday·August 11, 2015

1. 01*

   Decaying light particles in the SHiP experiment. II. Signal rate estimates for light neutralinos

   D. Gorbunov🇷🇺 · I. Timiryasov🇷🇺

   Considering the supersymmetric models with light neutralino and R-parity violation, we perform estimates of the signal rate expected at the recently proposed fixed target SHiP experiment exploiting CERN SPS beam of 400 GeV protons. We extend the existing studies by introducing new production channels (in particular through the beauty mesons) and decay modes. We also constrain model parameter space from analysis of negative results of the CHARM experiment.

   hep-phPRD(2015)·18 citations
2. 02*

   Sound of Dark Matter: Searching for Light Scalars with Resonant-Mass Detectors

   Asimina Arvanitaki🇨🇦 · Savas Dimopoulos🇺🇸 · Ken Van Tilburg🇺🇸

   The fine-structure constant and the electron mass in string theory are determined by the values of scalar fields called moduli. If the dark matter takes on the form of such a light modulus, it oscillates with a frequency equal to its mass and an amplitude determined by the local dark-matter density. This translates into an oscillation of the size of a solid that can be observed by resonant-mass antennas. Existing and planned experiments, combined with a dedicated resonant-mass detector proposed in this Letter, can probe dark-matter moduli with frequencies between 1 kHz and 1 GHz, with much better sensitivity than searches for fifth forces.

   hep-phhep-exPRL(2016)·164 citations
3. 03*

   Emerging lattice approach to the K-Unitarity Triangle

   Christoph Lehner🇺🇸 · Enrico Lunghi🇺🇸 · Amarjit Soni🇺🇸

   It has been clear for past many years that in low energy observables new physics can only appear as a perturbation. Therefore precise theoretical predictions and precise experimental measurements have become mandatory. Here we draw attention to the significant advances that have been made on the lattice in recent years in $K\to \pi \pi$, $\Delta M_K$, the long-distance part of $\epsilon$ and rare K-decays. Thus, in conjunction with experiments, the construction of a unitarity triangle purely from Kaon physics should soon become feasible. Along with the B-unitarity triangle, this should allow for more stringent tests of the Standard Model and tighter constraints on new physics.

   hep-phhep-exhep-latPLB(2016)·18 citations
4. 04*

   On $m_T$ dependence of femtoscopy scales for meson and baryon pairs

   Yu. M. Sinyukov🇺🇦 · V. M. Shapoval🇺🇦 · V. Yu. Naboka🇺🇦

   The $m_T$-dependencies of the femto-scales, the so-called interferometry and source radii, are investigated within the hydrokinetic model for different types of particle pairs - pion-pion, kaon-kaon, proton-proton and proton-lambda, - produced in Pb+Pb and $p+p$ collisions at the LHC. In particular, such property of the femto-scales momentum behavior as $m_T$-scaling is studied for the systems with (w) and without (w/o) intensive transverse flow, and also w and w/o re-scattering at the final afterburner stage of the matter evolution. The detail spatiotemporal description obtained within hydrokinetic model is compared with the simple analytical results for the spectra and longitudinal interferometry radii depending on the effective temperature on the hypersurface of maximal emission, proper time of such emission, and intensity of transverse flow. The derivation of the corresponding analytical formulas and discussion about a possibility for their utilization by the experimentalists for the simple femtoscopy data analysis is the main aim of this theoretical investigation.

   hep-phhep-exnucl-exnucl-thNPA(2016)·34 citations
5. 05*

   Five-body leptonic decays of muon and tau leptons

   A. Flores-Tlalpa🇲🇽 · G. López Castro🇲🇽 · P. Roig🇲🇽

   We study the five-body decays ${\mu }^{-}\to e^{-}{e}^{+}{e}^{-}{\nu }_{\mu }{\bar{\nu }}_e$ and ${\tau }^{-}\to {\ell }^{-}{\ell }^{\prime +}{\ell }^{\prime -}{\nu }_{\tau }{\bar{\nu }}_{\ell }$ for $\ell ,{\ell }^{\prime }=e,\mu$ within the Standard Model (SM) and in a general effective field theory description of the weak interactions at low energies. We compute the branching ratios and compare our results with two previous, mutually discrepant, SM calculations. By assuming a general structure for the weak currents we derive the expressions for the energy and angular distributions of the three charged leptons when the decaying lepton is polarized, which will be useful in precise tests of the weak charged current at Belle II. In these decays, leptonic $\mathbf{T}$-odd correlations in triple products of spin and momenta --which may signal time reversal violation in the leptonic sector-- are suppressed by the tiny neutrino masses. Therefore, a measurement of such $\mathbf{T}$-violating observables would be associated to neutrinoless lepton flavor violating (LFV) decays, where this effect is not extremely suppressed. We also study the backgrounds that the SM five-lepton lepton decays constitute to searches of LFV $L^{-}\to {\ell }^{-}{\ell }^{\prime +}{\ell }^{\prime -}$ decays. Searches at high values of the invariant mass of the ${\ell }^{\prime +}{\ell }^{\prime -}$ pair look the most convenient way to overcome the background.

   hep-phJHEP(2016)·47 citations
6. 06*

   Light top squarks in $U(1{)}_R$-lepton number model with a right handed neutrino and the LHC

   Sabyasachi Chakraborty🇮🇳 · AseshKrishna Datta🇮🇳 · Katri Huitu🇫🇮 · Sourov Roy🇮🇳 · Harri Waltari🇫🇮

   We investigate the phenomenology of top squarks at the Large Hadron Collider (LHC) in a supersymmetric model where lepton number is identified with an approximate $U(1{)}_R$ symmetry in such a way that one of the left chiral sneutrinos can acquire a large vacuum expectation value ($vev$) and can play the role of the down-type Higgs. This $R$-symmetry allows a subset of trilinear $R$-parity violating interactions, which determine the collider phenomenology of this model in a significant way. The gauginos are Dirac particles and gluinos are relatively heavy in this class of models. The model contains a right handed neutrino superfield, which gives a tree level mass to one of the active neutrinos. An order one neutrino Yukawa coupling also helps enhance the Higgs boson mass at the tree level and results in a very light bino-like neutralino (${\tilde{\chi }}_2^0$) with mass around a few hundred MeV, which is a carrier of missing (transverse) energy (\met). The model can accommodate two rather light top squarks, compatible with the observed mass of the Higgs boson. The lighter top squark (${\tilde{t}}_1$) can decay into $t{\tilde{\chi }}_2^0$, and thus the signal would be similar to the signal of top quark pair production at the LHC. In addition, fully visible decays such as ${\tilde{t}}_2\to b{e}^{+}$ can give rise to interesting final states. Such signals at the LHC combined with other features like a heavy gluino could provide a strong evidence for this kind of a model. Our analysis shows that $m_{{\tilde{t}}_1}\text{lsim}575(750)$ GeV and $m_{{\tilde{t}}_2}\text{lsim}1.2(1.4)$ TeV can be probed with 5$\sigma$ statistical significance at the 13 TeV LHC with 300~(3000) fb${}^{-1}$ of integrated luminosity. Finally, we observe that in the presence of super-light carriers of \met, the so-called `stealth' top squark scenario may naturally appear in our model.

   hep-phPRD(2016)·12 citations
7. 07*

   Automated higher-order calculations: Status and prospects

   Giovanni Ossola🇺🇸

   In this presentation we review the current status in the automated evaluation of scattering amplitudes, with particular attention to the developments related with NLO calculations, which led to the construction of powerful multi-purpose computational tools. After a general overview, we will devote a short section to describe the GoSam framework for NLO calculations and its application to the production of Higgs boson plus jets. We will then briefly comment on the challenges presented by NNLO calculations, whose structure is considerably more complicated. Finally, we will describe some of the features of the integrand-reduction techniques beyond NLO, an alternative promising approach to multi-loop calculations which is currently under development.

   hep-phPoS(2015)·2 citations
8. 08*

   Leptoquark induced rare decay amplitudes $h\to {\tau }^{\mp }{\mu }^{\pm }$ and $\tau \to \mu \gamma$

   Kingman Cheung🇹🇼 · Wai-Yee Keung🇺🇸 · Po-Yan Tseng🇹🇼

   Rare decay modes of the newly discovered standard-model-like Higgs boson $h$ may test the flavor changing couplings in the leptoquark sector through the process $h\to {\tau }^{\mp }{\mu }^{\pm }$. Motived by the recently reported excess in LHC data from the CMS detector, we found that a predicted branching fraction Br($h\to {\tau }^{\mp }{\mu }^{\pm }$) at the level of 1\% is possible even though the coupling parameters are subjected to the stringent constraint from the null observation of $\tau \to \mu \gamma$, where the destructive cancellation among amplitudes is achievable by fine tuning.

   hep-phPRD(2016)·64 citations
9. 09*

   The Lamb shift in muonic hydrogen and the proton radius from effective field theories

   Clara Peset🇪🇸 · Antonio Pineda🇪🇸

   We comprehensively analyse the theoretical prediction for the Lamb shift in muonic hydrogen, and the associated determination of the proton radius. We use effective field theories. This allows us to relate the proton radius with well-defined objects in quantum field theory, eliminating unnecessary model dependence. The use of effective field theories also helps us to organize the computation so that we can clearly state the parametric accuracy of the result. In this paper we review all (and check several of) the contributions to the energy shift of order ${\alpha }^5$, as well as those that scale like ${\alpha }^6\times$logarithms in the context of non-relativistic effective field theories of QED.

   hep-phnucl-thphysics.atom-phEPJA(2015)·34 citations
10. 10*

    Study of $\psi (3770)$ decaying to Baryon anti-Baryon Pairs

    Li-Gang Xia🇨🇳

    To study the decays of $\psi (3770)$ going to baryon anti-baryon pairs ($B\bar{B}$), all available experiments of measuring the cross sections of $e^{+}{e}^{-}\to B\bar{B}$ at center-of-mass energy ranging from 3.0 GeV to 3.9 GeV are combined. To relate the baryon octets, a model based on the SU(3) flavor symmetry is used and the SU(3) breaking effects are also considered. Assuming the elctric and magnetic form factors are equal ($|G_E|=|G_M|$), a global fit including the interference between the QED process and the resonant process is performed. The branching fraction of $\psi (3770)\to B\bar{B}$ is determined to be $(2.4\pm 0.8\pm 0.3)\times 10^{-5}$, $(1.7\pm 0.6\pm 0.1)\times 10^{-5}$, $(4.5\pm 0.9\pm 0.1)\times 10^{-5}$, $(4.5\pm 0.9\pm 0.1)\times 10^{-5}$, $(2.0\pm 0.7\pm 0.1)\times 10^{-5}$, and $(2.0\pm 0.7\pm 0.1)\times 10^{-5}$ for $B=p,\Lambda ,{\Sigma }^{+},{\Sigma }^0,{\Xi }^{-}$ and ${\Xi }^0$, respectively, where the first uncertainty is from the global fit and the second uncertainty is the systematic uncertainty due to the assumption $|G_E|=|G_M|$. They are at least one order of magnitude larger than a simple scaling of the branching fraction of $J/\psi \to B\bar{B}$.

    hep-phhep-exPLB(2016)·5 citations
11. 11*

    Hadron diffractive scattering at ultrahigh energies, real part of the amplitude and Coulomb interaction

    V.V. Anisovich🇷🇺 · V.A. Nikonov🇷🇺 · J. Nyiri🇭🇺

    On the basis of requirements of unitarity and analyticity we analyze the real and imaginary parts of the $p{p}^{\pm }$ scattering amplitudes at recent ultrahigh energies, 1-100 TeV. The predictions for the region $\sqrt{s}>100$ TeV and ${\mathbf{q}}^2<0.4$ GeV${}^2$ are given supposing the black disk asymptotic regime. It turns out that the real part of the amplitude is concentrated in the impact parameter space at the border of the black disk. The interplay of hadron and Coulomb interactions is discussed in terms of the $K$-matrix function. The $pp$ diffractive scattering cross section at 7 TeV is calculated with Coulomb interaction taken into account.

    hep-ph2 citations
12. 12*

    CP Violation in Predictive Neutrino Mass Structures

    Chao-Qiang Geng🇨🇳 · Da Huang🇹🇼 · Lu-Hsing Tsai🇹🇼

    We study the CP violation effects from two types of neutrino mass matrices with (i) $(M_{\nu }{)}_{ee}=0$, and (ii) $(M_{\nu }{)}_{ee}=(M_{\nu }{)}_{e\mu }=0$, which can be realized by the high dimensional lepton number violating operators ${\bar{\ell }}_R^c{\gamma }^{\mu }{L}_L(D_{\mu }\Phi ){\Phi }^2$ and ${\bar{\ell }}_R^c{l}_R(D_{\mu }\Phi {)}^2{\Phi }^2$, respectively. In (i), the neutrino mass spectrum is in the normal ordering with the lightest neutrino mass within the range $0.002\mathrm{eV}\lesssim m_0\lesssim 0.007\mathrm{eV}$. Furthermore, for a given value of $m_0$, there are two solutions for the two Majorana phases ${\alpha }_{21}$ and ${\alpha }_{31}$, whereas the Dirac phase $\delta$ is arbitrary. For (ii), the parameters of $m_0$, $\delta$, ${\alpha }_{21}$, and ${\alpha }_{31}$ can be completely determined. We calculate the CP violating asymmetries in neutrino-antineutrino oscillations for both mass textures of (i) and (ii), which are closely related to the CP violating Majorana phases.

    hep-phhep-exEPJC(2015)·3 citations
13. 13*

    Unified explanation of the $eejj$, diboson and dijet resonances at the LHC

    P. S. Bhupal Dev🇬🇧 · R. N. Mohapatra🇺🇸

    We show that the excess events observed in a number of recent LHC resonance searches can be simultaneously explained within a minimal non-supersymmetric left-right inverse seesaw model for neutrino masses with $W_R$ mass around 1.9 TeV. We further show that the minimal TeV-scale particle content that leads to gauge coupling unification in this model predicts $g_R\simeq 0.51$ at the TeV-scale. The extra color-singlet, $SU(2)$-triplet fermions required for unification can be interpreted as the Dark Matter of the Universe. Future measurements of the ratio of same-sign to opposite-sign dilepton events can provide a way to distinguish this scenario from the canonical cases of type-I and inverse seesaw, i.e. provide a measure of the relative magnitudes of the Dirac and Majorana masses of the right-handed neutrinos in the $SU(2{)}_R$-doublet of the left-right symmetric model.

    hep-phhep-exPRL(2015)·143 citations
14. 14*

    Signature of the $\gamma$+jet and dijet production mediated by an excited quark with QCD next-to-leading order accuracy at the LHC

    Yong Chuan Zhan🇨🇳 · Chong Sheng Li🇨🇳 · Ze Long Liu🇨🇳 · Shi Ang Li🇨🇳

    We present a detailed study of the production and decay of the excited quark at the QCD next-to-leading order (NLO) level at the Large Hadron Collider, using the narrow width approximation and helicity amplitudes method. We find that the QCD NLO corrections can tighten the constraints on the model parameters and reduce the scale dependencies of the total cross sections. We discuss the signals of the excited quark production with decay mode $q^{\ast }\to q\gamma$ and $q^{\ast }\to qg$, and present several important kinematic distributions. Moreover, we give the upper limits of the excited quark excluded mass range and the allowed parameter space for the coupling constants and the excited quark mass.

    hep-phPRD(2016)·2 citations
15. 15*

    Consistency of the triplet seesaw model revisited

    Cesar Bonilla🇪🇸 · Renato M. Fonseca🇪🇸 · José W.F. Valle🇪🇸

    Adding a scalar triplet to the Standard Model is one of the simplest ways of giving mass to neutrinos, providing at the same time a mechanism to stabilize the theory's vacuum. In this paper, we revisit these aspects of the type-II seesaw model pointing out that the bounded-from-below conditions for the scalar potential in use in the literature are not correct. We discuss some scenarios where the correction can be significant and sketch the typical scalar boson profile expected by consistency.

    hep-phPRD(2015)·79 citations
16. 16*

    Effect of $c\overline{c}$ resonances in the branching ratio and forward-backward asymmetry of the decay $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$

    Mohammad Ahmady🇨🇦 · Dan Hatfield🇨🇦 · Sébastien Lord🇨🇦 · Ruben Sandapen🇨🇦

    We compute the branching ratio and forward-backward asymmetry ($A_{FB}$) distribution for the rare dileptonic decay $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ for the full range of $q^2$, the dimuon mass squared, region. For the required form factors, we use nonperturbative inputs as predicted by the anti-de Sitter (AdS)/QCD correspondence. When using the Breit-Wigner model with momentum-dependent decay constants to account for the $\psi$ and ${\psi }^{\prime }$ resonance effects in the nonresonance region of the spectrum, we find our predictions to be in better agreement with the experimental data for the branching ratio.

    hep-phPRD(2015)·8 citations
17. 17*

    A4-based see-saw model for realistic neutrino masses and mixing

    Soumita Pramanick🇮🇳 · Amitava Raychaudhuri🇮🇳

    We present an $A4$-based model where neutrino masses arise from a combination of see-saw mechanisms. The model is motivated by several small mixing and mass parameters indicated by the data. These are ${\theta }_{13}$, the solar mass splitting, and the small deviation of ${\theta }_{23}$ from maximal mixing (= $\pi /4$). We take the above as indications that at some level the small quantities are well-approximated by zero. In particular the mixing angles, to a zero order, should be either 0 or $\pi /4$. Accordingly, in this model the Type-II see-saw dominates and generates the larger atmospheric mass splitting and sets ${\theta }_{23}=\pi /4$. The other mixing angles are vanishing as is the solar splitting. We show how the $A4$ assignment for the lepton doublets leads to this form. We also specify the $A4$ properties of the right-handed neutrinos which result in a smaller Type-I see-saw contribution that acts as a perturbation and shifts the angles ${\theta }_{12}$ and ${\theta }_{13}$ into the correct range and the desired value of $\Delta m_{solar}^2$ is produced. The $A4$ symmetry results in relationships between these quantities as well as with a small deviation of ${\theta }_{23}$ from $\pi /4$. If the right-handed neutrino mass matrix, $M_R$, is chosen real then there is no leptonic CP-violation and only Normal Ordering is admissible. If $M_R$ is complex then Inverted Ordering is also allowed with the proviso that the CP-phase, $\delta$, is large, i.e., $\sim \pi /2$ or $-\pi /2$. The preliminary results from NO$\nu$A favouring Normal Ordering and $\delta$ near $-\pi /2$ imply quasi-degenerate neutrino masses in this model.

    hep-phhep-exPRD(2016)·28 citations
18. 18*

    Helicity of spin-extended chiral particles

    M. Elbistan🇨🇳 · C. Duval🇫🇷 · P. A. Horvathy🇨🇳 · P.-M. Zhang🇨🇳

    The helicity of a free massless relativistic particle, ${\chi }^o=\mathbf{s}.\mathbf{p}/|\mathbf{p}|$, is generalized, for a particle in an electromagnetic field, to $\chi =\mathbf{s}.\mathbf{p}/\mathcal{E}$, where $\mathcal{E}$ is the modified kinetic energy. Both ${\chi }^o$ and $\chi$ coincide and are conserved for minimal coupling (gyromagnetic ratio $g=0$) but are different and neither of them is conserved when the coupling is non-minimal, $g\ne 0$, generating non-zero effective mass. For a chiral particle with $g=2$ in a constant electric field both helicities converge asymptotically to the same value. Helicity is also conserved for minimal gravitational coupling.

    ↳ hep-thcond-mat.otherhep-phPLA(2016)·7 citations
19. 19*

    Observation of half-quantum vortices in topological superfluid 3He

    S. Autti🇫🇮 · V.V. Dmitriev🇷🇺 · J.T. Mäkinen🇫🇮 · A.A. Soldatov🇷🇺 · G.E. Volovik🇫🇮 · A.N. Yudin🇷🇺 · V.V. Zavjalov🇫🇮 · V.B. Eltsov🇫🇮

    One of the most sought-after objects in topological quantum matter systems is a vortex carrying half a quantum of circulation. They were originally predicted to exist in superfluid 3He-A, but have never been resolved there. Here we report an observation of half-quantum vortices (HQVs) in the polar phase of superfluid 3He. The vortices are created with rotation or by the Kibble-Zurek mechanism and identified based on their nuclear magnetic resonance signature. This discovery provides a pathway for studies of unpaired Majorana modes bound to the HQV cores in the polar-distorted A phase.

    ↳ cond-mat.otherhep-phPRL(2016)·67 citations
20. 20*

    Simple way to the high-temperature expansion of relativistic Fermi-Dirac integrals

    A.S. Khvorostukhin🇷🇺

    The pressure of an ideal relativistic Fermi gas is computed as an infinite series for high temperatures at nonzero chemical potentials. The expansion of the particle number density, scalar density, and entropy density as first derivatives of the pressure is also found.

    ↳ math-phhep-phhep-thmath.MP+1PRD(2015)·4 citations
21. 21*

    Disruption of Cosmic String Wakes by Gaussian Fluctuations

    Robert H. Brandenberger🇨🇦 · Oscar F. Hernández🇨🇦 · Disrael C. N. da Cunha🇨🇦

    We study the stability of cosmic string wakes against the disruption by the dominant Gaussian fluctuations which are present in cosmological models. We find that for a string tension given by $G\mu =10^{-7}$ wakes remain locally stable until a redshift of $z=6$, and for a value of $G\mu =10^{-14}$ they are stable beyond a redshift of $z=20$. We study a global stability criterion which shows that wakes created by strings at times after $t_{eq}$ are identifiable up to the present time, independent of the value of $G\mu$. Taking into account our criteria it is possible to develop strategies to search for the distinctive position space signals in cosmological maps which are induced by wakes.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2016)·15 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.