We describe an efficient, construction independent, algorithmic test to determine whether Calabi-Yau threefolds admit a structure compatible with the large volume moduli stabilization scenario of type IIB superstring theory. Using the algorithm, we scan complete intersection and toric hypersurface Calabi-Yau threefolds with $2\le h^{1,1}\le 4$ and deduce that 418 among 4434 manifolds have a large volume limit with a single large four-cycle. We describe major extensions to this survey, which are currently underway.

The usual nuclear recoil energy reconstruction employed by liquid xenon dark matter search experiments relies only on the primary scintillation photon signal. Energy reconstruction based on both the photon and electron signals yields a more accurate representation of search results. For a dark matter particle of mass $m_{\chi }\sim 10\mathrm{GeV}$, a nuclear recoil from a scattering event is more likely to be observed in the lower-left corner of the typical search box, rather than near the nuclear recoil calibration centroid. In this region of the search box, the actual nuclear recoil energies are smaller than the usual energy scale suggests, by about a factor of 2. Recent search results from the XENON100 experiment are discussed in light of these considerations.

Weak interactions between quarks give rise to hadronic parity violation which can be observed in nuclear and few-nucleon systems. We study the QCD renormalization of the isotensor component of parity violation at next-to-leading order accuracy. The renormalization group is employed to evolve the interaction down to hadronic scales. As the results are renormalization-scheme dependent, we compare various schemes, including ’t Hooft-Veltman dimensional regularization and several regularization-independent momentum subtraction schemes.

We calculate the baryon asymmetry produced at the electroweak phase transition by quasidegenerate third-generation sfermions in the minimal supersymmetric extension of the Standard Model. We evaluate constraints from Higgs searches, from collider searches for supersymmetric particles, and from null searches for the permanent electric dipole moment of the electron, of the neutron and of atoms. We find that resonant sfermion sources can in principle provide a large enough baryon asymmetry in various corners of the sfermion parameter space, and we focus, in particular, on the case of large $\tan \beta$, where third-generation down-type (s)fermions become relevant. We show that in the case of top squark and sbottom sources, the viable parameter space is ruled out by constraints from the nonobservation of the Mercury electric dipole moment. We introduce a new class of $CP$-violating sources, quasidegenerate staus, that escapes current electric dipole moment constraints while providing large enough net chiral currents to achieve successful slepton-mediated electroweak baryogenesis.

Lattice results are available for $\Delta S=2$ matrix elements for the first time in full QCD, which improve considerably the status of hadronic uncertainties in $K\mathrm{\text{−}}\overline{K}$ mixing with respect to earlier phenomenological studies. Using an average of the ETMC and RBC-UKQCD results, we analyze ${ϵ}_K$ in natural supersymmetry (SUSY). This scenario arises as a consistent BSM framework after the latest results from the LHC. The analysis is improved with respect to previous studies including next-to-leading order matching conditions of order ${\alpha }_s^3$. We derive new bounds for SUSY mass insertions in the scenario with a light third generation and study the implications for squark and gluino masses, compared with direct searches at the LHC. Assuming natural values for the flavor-violating SUSY couplings of both chiralities, we find that the sbottom must be heavier than 3 TeV for a gluino mass up to 10 TeV. In this scenario no natural values for squark and gluino masses can satisfy the flavor bounds.

We study the parameter space of the constrained exceptional supersymmetric standard model (${\mathrm{cE}}_6\mathrm{SSM}$) consistent with a Higgs signal near 125 GeV and the LHC searches for squarks, gluinos and $Z^{\prime }$. The ${\mathrm{cE}}_6\mathrm{SSM}$ parameter space, consistent with correct electroweak symmetry breaking, is represented by scans in the $(m_0,M_{1/2})$ plane for fixed $Z^{\prime }$ mass and $\tan \beta$, with squark, gluino and Higgs masses plotted as contours in this plane. We find that a 125 GeV Higgs mass only arises for a sufficiently large $Z^{\prime }$ mass, mostly above current limits, and for particular regions of squark and gluino masses corresponding to multi-TeV squark masses, but with lighter gluinos typically within reach of the LHC 8 TeV or forthcoming 14 TeV runs. Successful dark matter relic abundance may be achieved over all the parameter space, assuming a binolike lightest supersymmetric particle with a nearby heavier inert Higgsino doublet and decoupled inert singlinos, resulting in conventional gluino decay signatures. A set of typical benchmark points with a Higgs near 125 GeV is provided which exemplifies these features.

Introducing an $R$-symmetry to models of high scale supersymmetry (SUSY) can have interesting consequences, and we focus on two aspects. If Majorana masses are forbidden by an $R$-symmetry and the main source of electroweak gaugino masses are Dirac terms, then the Higgs quartic coupling vanishing at the SUSY scale and the Higgs boson mass will be near 125 GeV. Moreover, using an $R$-symmetry, models with only one Higgs doublet in the UV can be constructed and we argue that, since we desire only a single Higgs at the weak scale, this scenario is more aesthetic than existing models. We subsequently present a model which draws on both of these features. We comment on neutrino masses and dark matter in these scenarios and discuss how the models presented can be discerned from alternative constructions with high scale SUSY, including split SUSY.

Most of the discussion regarding the Higgs boson couplings to Standard Model vector bosons and fermions is presented with respect to what present and future collider detectors will be able to measure. Here, we ask the more physics-based question of how well do we need to measure the Higgs boson couplings? We first present a reasonable definition of “need” and then investigate the answer in the context of various highly motivated new physics scenarios: supersymmetry, mixed-in hidden sector Higgs bosons, and a composite Higgs boson. We find the largest coupling deviations away from the Standard Model Higgs couplings that are possible if no other state related to EWSB is directly accessible at the LHC. Depending on the physics scenario under consideration, we find targets that range from less than 1% to 10% for vector bosons, and from a few percent to tens of percent for couplings to fermions.

We propose a method for calculating DIS jet production cross sections in QCD at NLO accuracy with consistent treatment of heavy quarks. The scheme relies on the dipole subtraction method for jets, which we extend to all possible initial state splittings with heavy partons, so that the Aivazis-Collins-Olness-Tung massive collinear factorization scheme can be applied. As a first check of the formalism we recover the Aivazis-Collins-Olness-Tung result for the heavy quark structure function using a dedicated Monte Carlo program.

Recently it has been put forward that linearly polarized gluons inside unpolarized protons affect the transverse momentum distribution of final state particles in hadronic collisions. They lead to a characteristic modulation of the differential cross section in Higgs production and to azimuthal asymmetries in, for instance, heavy quark pair production. Here we study the effect on charmonium and bottomonium production in hadronic collisions, such as at LHCb and at the proposed fixed target experiment AFTER at LHC. We focus mainly on the scalar and pseudoscalar quarkonia, ${\eta }_c$, ${\chi }_{c0}$, ${\eta }_b$, ${\chi }_{b0}$, which allow for an angular independent investigation. Within the framework of transverse momentum dependent factorization in combination with the nonrelativistic QCD based color-singlet quarkonium model, we show for small transverse momentum ($q_T^2\ll 4M_Q^2$) that the scalar and pseudoscalar quarkonium production cross sections are modified in different ways by linearly polarized gluons, while their effects on the production of higher angular momentum quarkonium states are strongly suppressed. Comparisons to ${\chi }_{c2}$, ${\chi }_{b2}$ production can help to cancel out uncertainties. Together with the analogous study in Higgs production at LHC, quarkonium production can moreover be used to test the scale dependence of the linearly polarized gluon distribution over a large energy range.

We show how single top production at the LHC can be used to discover (and characterize the couplings of) $B^{\prime }$ quarks, which are an essential part of many natural models of new physics beyond the Standard Model. We present the $B^{\prime }$ effective model and concentrate on resonant production via a colored anomalous magnetic moment. Generally, $B^{\prime }$s preferentially decay into a single top quark produced in association with a $W$ boson; thus, this production process makes associated single top production essential to $B^{\prime }$ searches at the LHC. We demonstrate the background processes are manageable and the signal cross section is sufficient to yield a large signal significance even during the 7 TeV LHC run. Specifically, we show that $B^{\prime }$ masses of 700 GeV or more can be probed. Moreover, if a $B^{\prime }$ is found, then the chirality of its coupling can be determined. Finally, we present signal cross sections for several different LHC energies.

We numerically simulate ensembles of SU(2) Yang-Mills dimeron solutions with a statistical weight determined by the classical action and perform a comprehensive analysis of their properties as a function of the bare coupling. In particular, we examine the extent to which these ensembles and their classical gauge interactions capture topological and confinement properties of the Yang-Mills vacuum. This also allows us to put the classic picture of meron-induced quark confinement, with the confinement-deconfinement transition triggered by dimeron dissociation, to stringent tests. In the first part of our analysis we study spacial, topological-charge and color correlations at the level of both the dimerons and their meron constituents. At small to moderate couplings, the dependence of the interactions between the dimerons on their relative color orientations is found to generate a strong attraction (repulsion) between nearest neighbors of opposite (equal) topological charge. Hence, the emerging short- to mid-range order in the gauge-field configurations screens topological charges. With increasing coupling this order weakens rapidly, however, in part because the dimerons gradually dissociate into their less localized meron constituents. Monitoring confinement properties by evaluating Wilson-loop expectation values, we find the growing disorder due to the long-range tails of these progressively liberated merons to generate a finite and (with the coupling) increasing string tension. The short-distance behavior of the static quark-antiquark potential, on the other hand, is dominated by small, “instantonlike” dimerons. String tension, action density and topological susceptibility of the dimeron ensembles in the physical coupling region turn out to be of the order of standard values. Hence, the above results demonstrate without reliance on weak-coupling or low-density approximations that the dissociating dimeron component in the Yang-Mills vacuum can indeed produce a meron-populated confining phase. The density of coexisting, hardly dissociated and thus instantonlike dimerons seems to remain large enough, on the other hand, to reproduce much of the additional phenomenology successfully accounted for by nonconfining instanton vacuum models. Hence, dimeron ensembles should provide an efficient basis for a more complete description of the Yang-Mills vacuum.

Weak radiative decay $\overline{B}\to X_s\gamma$ is known to be a loop-generated process. However, it does receive tree-level contributions from Cabibbo-Kobayashi-Maskawa-suppressed $b\to u\overline{u}s\gamma$ transitions. In the present paper, we evaluate such contributions together with similar ones from the QCD penguin operators. For a low value of the photon energy cutoff $E_0\simeq m_b/20$ that has often been used in the literature, they can enhance the inclusive branching ratio by more than 10%. For $E_0=1.6\mathrm{GeV}$ or higher, the effect does not exceed 0.4%, which is due to phase-space suppression. Our perturbative results contain collinear logarithms that depend on the light quark masses $m_q$ ($q=u$, $d$, $s$). We have allowed $m_b/m_q$ to vary from 10 to 50, which corresponds to values of $m_q$ that are typical for the constituent quark masses. Such a rough method of estimation may be improved in the future with the help of fragmentation functions once the considered effects begin to matter in the overall error budget for $\mathcal{B}(\overline{B}\to X_s\gamma )$.

On the basis of perturbative QCD and the relativistic quark model, we calculate relativistic corrections to the process of pair $J/\psi$ production in proton-proton collisions at LHC energy $\sqrt{S}=7\mathrm{TeV}$. Relativistic terms in the production amplitude connected with the relative motion of heavy quarks and the transformation law of the bound state wave functions to the reference frame of moving $J/\psi$ mesons are taken into account. For the gluon and quark propagators entering the amplitude, we use a truncated expansion in relative quark momenta up to the second order. Relativistic corrections to the quark bound state wave functions are considered by means of the Breit-like potential. It turns out that the examined effects decrease initial nonrelativistic cross section more than two times. The final result lies below the experimental value measured by LHCb.

We consider cumulant moments (cumulants) of the thrust distribution using predictions of the full spectrum for thrust including $\mathcal{O}({\alpha }_s^3)$ fixed order results, resummation of singular ${\mathrm{N}}^3\mathrm{LL}$ logarithmic contributions, and a class of leading power corrections in a renormalon-free scheme. From a global fit to the first thrust moment we extract the strong coupling and the leading power correction matrix element ${\Omega }_1$. We obtain ${\alpha }_s(m_Z)=0.1140\pm (0.0004{)}_{\exp }\pm (0.0013{)}_{\mathrm{hadr}}\pm (0.0007{)}_{\mathrm{pert}}$, where the $1\mathrm{\text{−}}\sigma$ uncertainties are experimental, from hadronization (related to ${\Omega }_1$) and perturbative, respectively, and ${\Omega }_1=0.377\pm (0.044{)}_{\exp }\pm (0.039{)}_{\mathrm{pert}}\mathrm{GeV}$. The $n$th thrust cumulants for $n\ge 2$ are completely insensitive to ${\Omega }_1$, and therefore a good instrument for extracting information on higher order power corrections, ${\Omega }_n^{\prime }/Q^n$, from moment data. We find $({\tilde{\Omega }}_2^{\prime }{)}^{1/2}=0.74\pm (0.11{)}_{\exp }\pm (0.09{)}_{\mathrm{pert}}\mathrm{GeV}$.

In the perturbative QCD approach, we investigate the $B(B_s)\to D_{(s)}({\overline{D}}_{(s)})T$ and $D_{(s)}^{*}({\overline{D}}_{(s)}^{*})T$ decays, which include the Cabibbo-Kobayashi-Maskawa-favored (CKM-favored) decays and the Cabibbo-Kobayashi-Maskawa-suppressed decays, where $T$ denotes a light tensor meson. From our calculations, we find that the nonfactorizable emission diagrams and the annihilation-type diagrams are important, especially for those color-suppressed channels. For those decays with a tensor meson emitted, the factorizable emission diagrams vanish owing to the fact that a tensor meson cannot be produced through the local ($V-A$) or tensor current. The numerical results show that the predictions for the branching ratios of considered charmed $B$ decays are in the range of ${10}^{-4}$ to ${10}^{-6}$ for those CKM-favored decays (governed by $|V_{cb}|$) and in the range of ${10}^{-5}$ to ${10}^{-8}$ for those CKM-suppressed decays (governed by $|V_{ub}|$). We also predict large transverse polarization contributions in many of the $B(B_s)\to D_{(s)}^{*}({\overline{D}}_{(s)}^{*})T$ decay channels.

Galaxy clusters are one of the most promising candidate sites for dark matter (DM) annihilation. We focus on DM ($\chi$) with mass in the range of 10 GeV–100 TeV, annihilating through the channels $\chi \chi \to {\mu }^{+}{\mu }^{-}$, $\chi \chi \to \nu \overline{\nu }$, $\chi \chi \to t\overline{t}$, or $\chi \chi \to \nu \overline{\nu }\nu \overline{\nu }$, and forecast the expected sensitivity to the annihilation cross section into these channels by observing galaxy clusters at IceCube/KM3NeT. Optimistically, the presence of DM substructures in galaxy clusters is predicted to enhance the signal by 2–3 orders of magnitude over the contribution from the smooth component of the DM distribution. Optimizing for the angular size of the region of interest for galaxy clusters, the sensitivity to the annihilation cross section, $⟨\sigma v⟩$, of heavy DM with mass in the range of 300 GeV–100 TeV will be $\mathcal{O}({10}^{-24}{\mathrm{cm}}^3{\mathrm{s}}^{-1})$ for full IceCube/KM3NeT live time of 10 years, which is about one order of magnitude better than the best limit that can be obtained by observing the Milky Way halo. We find that neutrinos from cosmic ray interactions in the galaxy cluster, in addition to the atmospheric neutrinos, are a source of background. We show that significant improvement in the experimental sensitivity can be achieved for lower DM masses in the range of 10–300 GeV if neutrino-induced cascades can be reconstructed to $\approx 5°$ accuracy, as may be possible in KM3NeT. We, therefore, propose that a low-energy extension “KM3NeT-Core,” similar to DeepCore in IceCube, be considered for an extended reach at low DM masses.

In our recent analysis of lattice data of the BMW, LHPC and PACS-CS groups we determined a parameter set of the chiral Lagrangian that allows a simultaneous description of the baryon octet and decuplet masses as measured by those lattice groups. The results on the baryon spectrum of the HSC group were recovered accurately without their inclusion into our six parameter fit. We show that the same parameter set provides an accurate reproduction of the recent results of the QCDSF-UKQCD group probing the baryon masses at quite different quark masses. This shows a remarkable consistency amongst the different lattice simulations. With even more accurate lattice data in the near future it will become feasible to determine all low-energy parameters relevant at ${\mathrm{N}}^3\mathrm{LO}$.

Although the analysis of the BABAR Collaboration prefers $J^P=0^{+}$ for the $X(3915)$, it is difficult to assign the $X(3915)$ to the ${\chi }_{c0}(2P)$. We show that there is an indication of the ${\chi }_{c0}(2P)$ with a mass around 3840 MeV and width of about 200 MeV in the Belle and BABAR data for $\gamma \gamma \to D\overline{D}$.